Curable composition for ink jet for metal-containing substrate, solder resist, and ink jet recording method

Abstract

The present invention addresses the problem of providing a curable composition for inkjet for a metal-containing base material, which is capable of suppressing changes in viscosity, particle diameter, and discoloration prevention performance over time at high temperatures. The present invention also addresses the problem of providing a solder resist and an ink jet recording method which use the curable ink jet composition for a metal-containing base material and which achieve improved adhesion, hardness, solder heat resistance and plating resistance over time at high temperatures. This curable composition for ink jet for a metal-containing base material contains a polymerizable compound, a polymerization initiator and a pigment, and is cured by irradiation with active rays. The curable composition for ink jet for a metal-containing base material contains a nitrogen-containing aromatic heterocyclic compound having a tertiary amine.

Description

Technical Field

[0001] The present invention relates to a curable composition for inkjet for a metal-containing substrate, a solder resist, and an inkjet recording method. In particular, the present invention relates to a curable composition for inkjet for a metal-containing substrate capable of suppressing changes in viscosity, particle size, and anti-discoloration performance over time at high temperatures, a solder resist having excellent coating film properties, and the like. Background Art

[0002] As disclosed in Patent Document 1, it is known to contain nitrogen-containing aromatic heterocyclic compounds such as melamine, benzotriazole, and triazole in alkali-developable photoresists. This technology can promote the close adhesion between the photoresist and the substrate (such as copper) and suppress discoloration of the substrate.

[0003] On the other hand, it is known that in a printed wiring board in a printed circuit board, in order to protect a circuit pattern, an insulating film (solder resist) formed by applying ink and curing it is formed by an inkjet method. Specifically, inkjet ink is applied, cured by active rays, and then cured by heat. Hereinafter, inkjet ink is also referred to as "ink".

[0004] In such a solder resist ink, Patent Document 2 discloses a technique of promoting adhesion with copper by adding a nitrogen-containing aromatic heterocyclic compound.

[0005] However, the solder resist ink described in Patent Document 2 has a problem that discoloration of the coating film and the base material under the coating film during the curing step and the soldering step is not sufficiently suppressed.

[0006] In addition, in order to obtain proper ejection, inkjet ink is often heated to reduce viscosity before use. Therefore, it is hoped that the viscosity, particle size, adhesion and hardness of the ink, and anti-discoloration performance required as a solder resist will not change over time at high temperatures. However, it is more difficult to achieve such performance.

[0007] Prior art literature

[0008] Patent Literature

[0009] Patent Document 1: International Publication No. 2014 / 167671

[0010] Patent Document 2: Japanese Patent No. 5986701 Summary of the invention

[0011] Problems to be solved by the invention

[0012] The present invention is made in view of the above problems and conditions. The problem to be solved by the present invention is to provide a curable composition for inkjet for a metal-containing substrate that can suppress changes in viscosity and particle size at high temperatures over time and changes in the anti-discoloration performance of the coating film and the substrate under the coating film. In addition, the subject of the present invention is to achieve improvements in the adhesion of the coating film and the hardness, heat resistance, and plating resistance at high temperatures over time in a solder resist and an inkjet recording method using the above-mentioned curable composition for inkjet for a metal-containing substrate.

[0013] Means for solving problems

[0014] The present inventors have studied the causes of the above problems in order to solve the above problems. The present inventors have found that by including a polymerizable compound, a polymerization initiator, a pigment, and a nitrogen-containing aromatic heterocyclic compound having a tertiary amine in a curable composition for inkjet for a metal-containing substrate, it is possible to suppress changes in viscosity, particle size, and anti-discoloration performance for a coating film and a substrate under the coating film over time at high temperatures. It has also been found that, in the case of a solder resist using such a curable composition for inkjet for a metal-containing substrate, improvements in adhesion, hardness, heat resistance, and plating resistance are also achieved under high temperature over time.

[0015] That is, the above-mentioned problems according to the present invention are solved by the following means.

[0016] 1. A curable composition for inkjet for a metal-containing substrate, comprising a polymerizable compound, a polymerization initiator and a pigment, and curing by irradiation with active rays, characterized in that it contains a nitrogen-containing aromatic heterocyclic compound having a tertiary amine.

[0017] 2. The curable composition for inkjet according to item 1, wherein the nitrogen-containing aromatic heterocyclic compound has a benzene ring that is not directly fused to an aromatic heterocyclic ring.

[0018] 3. The curable composition for inkjet for a metal-containing substrate according to item 1, wherein the polymerizable compound is a polymerizable compound having a carboxyl group, a hydroxyl group or an epoxy group.

[0019] 4. The curable composition for inkjet for a metal-containing substrate according to item 1, wherein the nitrogen-containing aromatic heterocyclic compound contains a five-membered nitrogen-containing aromatic heterocyclic compound.

[0020] 5. The curable composition for inkjet for a metal-containing substrate according to item 1, wherein the nitrogen-containing aromatic heterocyclic compound contains a triazole compound.

[0021] 6. The curable composition for inkjet for a metal-containing substrate according to item 5, wherein the triazole compound has a structure represented by the following general formula (a):

[0022]

Chemistry 1

[0023] General formula (a)

[0024]

[0025] [In the above general formula (a), Ra and Rb each represent an alkyl group having 1 to 20 carbon atoms.]

[0026] 7. The curable composition for inkjet for a metal-containing substrate according to item 3, wherein the polymerizable compound having a carboxyl group has a structure represented by the following general formula (1).

[0027]

Chemistry 2

[0028] General formula (1)

[0029]

[0030] [In the above general formula (1), X represents a substituent having at least one selected from the group consisting of acryloyl group, methacryloyl group, allyl group, vinyl group and derivatives thereof at the terminal.

[0031] 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.

[0032] R1 represents an unsubstituted alkylene group having 1 to 6 carbon atoms.]

[0033] 8. The curable composition for inkjet for a metal-containing substrate according to item 3, wherein the polymerizable compound having a hydroxyl group is an epoxy acrylate obtained by reacting (meth)acrylic acid with an epoxy compound.

[0034] 9. The curable composition for inkjet for a metal-containing substrate according to item 3, wherein the polymerizable compound having a carboxyl group, a hydroxyl group or an epoxy group has any one of a bisphenol structure, a cresol novolac structure or a phenol novolac structure.

[0035] 10. The curable composition for inkjet for a metal-containing substrate according to item 1, wherein the composition contains thioxanthone as the polymerization initiator.

[0036] 11. The curable composition for inkjet for a metal-containing substrate according to item 1, which contains N-oxyls or nitrosoamines as a polymerization inhibitor.

[0037] 12. A solder resist comprising the curable composition for inkjet for a metal-containing substrate according to any one of items 1 to 11.

[0038] 13. An inkjet recording method, which is an inkjet recording method in which a curable inkjet composition is discharged onto a substrate and cured by active radiation, characterized in that as the above-mentioned curable inkjet composition, a curable inkjet composition for a substrate containing a metal as described in any one of items 1 to 11 is used, and as the above-mentioned substrate, a substrate containing a metal is used.

[0039] 14. The inkjet recording method according to item 13, further comprising a step of heating the substrate at 140° C. or higher.

[0040] 15. The inkjet recording method according to item 13, further comprising the step of heating the curable composition for inkjet for the metal-containing substrate to 40° C. or higher in an inkjet head.

[0041] Effects of the Invention

[0042] By means of the present invention, a curable composition for inkjet for a metal-containing substrate can be provided, which can suppress changes in viscosity, particle size, and anti-discoloration performance over time at high temperatures. In addition, a solder resist and an inkjet recording method can be provided, which use the curable composition for inkjet for a metal-containing substrate and achieve improved adhesion, hardness, heat resistance, and plating resistance over time at high temperatures.

[0043] The manifestation mechanism and action mechanism of the effects of the present invention are not yet clear, but are presumed as follows.

[0044] (Nitrogen-containing aromatic heterocyclic compound having a tertiary amine)

[0045] In the case where the aromatic heterocyclic compound does not have a tertiary amine, the aromatic heterocyclic compound (such as melamine, benzotriazole) adsorbs to the pigment and dispersant, hindering the adsorption of the dispersant to the pigment. As a result, the pigment aggregates, and the viscosity and particle size of the ink increase. In addition, the amount of aromatic heterocyclics that interact with the substrate decreases, and the anti-discoloration performance and adhesion performance are no longer exerted.

[0046] In contrast, as in the present invention, the nitrogen-containing aromatic heterocyclic compound has a tertiary amine, and the nitrogen-containing aromatic heterocyclic ring is difficult to interact with the pigment due to the steric hindrance of the tertiary amine. Therefore, the aggregation of the pigment is suppressed, and the viscosity and particle size of the ink can be prevented from increasing. In addition, the aromatic heterocyclic ring that interacts with the substrate will not decrease, and discoloration can be prevented. In particular, the viscosity and particle size of the ink can be prevented from increasing over time at high temperatures. In addition, when a cured film such as a solder resist is made, the heat resistance and plating resistance are improved, and the adhesion and hardness to the substrate are improved. DETAILED DESCRIPTION

[0047] The curable composition for inkjet for a metal-containing substrate of the present invention contains a polymerizable compound, a polymerization initiator and a pigment, and is cured by irradiation with active rays, and is characterized in that it contains a nitrogen-containing aromatic heterocyclic compound having a tertiary amine.

[0048] This feature is a common or corresponding technical feature of the following embodiments.

[0049] As an embodiment of the present invention, the polymerizable compound is preferably a polymerizable compound having a carboxyl group, a hydroxyl group, or an epoxy group in order to improve the adhesion between a cured film of a solder resist or the like and a substrate.

[0050] In terms of improving the anti-discoloration performance at high temperatures over time, the nitrogen-containing aromatic heterocyclic compound is preferably a five-membered nitrogen-containing aromatic heterocyclic compound.

[0051] In terms of improving the anti-discoloration performance at high temperatures over time, the nitrogen-containing aromatic heterocyclic compound preferably contains a triazole compound.

[0052] When formed into a cured film such as a solder resist, the triazole compound preferably has a structure represented by the following general formula (a) in terms of excellent plating resistance.

[0053]

Chemistry 3

[0054] General formula (a)

[0055]

[0056] [In the above general formula (a), Ra and Rb each represent an alkyl group having 1 to 20 carbon atoms.]

[0057] The polymerizable compound having a carboxyl group has a structure represented by the following general formula (1), and is preferably used because it contains a dicarboxylic acid, thereby improving the adhesion between the solder resist and copper as a substrate.

[0058]

Chemistry 4

[0059] General formula (1)

[0060]

[0061] [In the above general formula (1), X represents a substituent having at least one selected from the group consisting of acryloyl group, methacryloyl group, allyl group, vinyl group and derivatives thereof at the terminal.

[0062] 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.

[0063] R1 represents an unsubstituted alkylene group having 1 to 6 carbon atoms.]

[0064] In order to further improve the adhesion between the solder resist and the base material, the polymerizable compound having a hydroxyl group is preferably an epoxy acrylate obtained by reacting (meth)acrylic acid with an epoxy compound.

[0065] In terms of improving the heat resistance of the solder resist, the polymerizable compound having a carboxyl group, a hydroxyl group, or an epoxy group preferably has any one of a bisphenol structure, a cresol novolac structure, or a phenol novolac structure.

[0066] The curable composition for inkjet preferably contains thioxanthone as the polymerization initiator in order to improve the plating resistance of a cured film formed at a high temperature over time.

[0067] In order to improve the storage stability of the ink, it is preferred to contain N-oxyls or nitrosoamines as a polymerization inhibitor.

[0068] The curable composition for inkjet for a metal-containing substrate of the present invention is suitable for use in a solder resist.

[0069] The inkjet recording method of the present invention is an inkjet recording method in which a curable inkjet composition is discharged onto a substrate and cured by active radiation, and is characterized in that as the above-mentioned curable inkjet composition, the curable inkjet composition for a metal-containing substrate of the present invention is used, and as the above-mentioned substrate, a metal-containing substrate is used.

[0070] Thereby, the physical properties of the solder resist composed of the inkjet curable composition for a substrate containing a metal can be improved.

[0071] In order to improve the hardness of the solder resist, it is preferable to include a step of heating the substrate at 140° C. or higher.

[0072] In order to further improve the discharge properties from the inkjet head, it is preferred to include a step of heating the metal-containing substrate inkjet curable composition to 40° C. or higher in the inkjet head.

[0073] The present invention and its constituent elements and forms and modes for carrying out the present invention are described below. It should be noted that in the present application, "to" is used to mean that the numerical values ​​described before and after it are included as the lower limit and the upper limit.

[0074] [Curable composition for inkjet]

[0075] The curable composition for inkjet for a metal-containing substrate of the present invention contains a polymerizable compound, a polymerization initiator and a pigment, and is cured by irradiation with active rays, and is characterized in that it contains a nitrogen-containing aromatic heterocyclic compound having a tertiary amine.

[0076] Hereinafter, the curable composition for inkjet for a metal-containing substrate of the present invention is also simply referred to as “curable composition for inkjet”, “curable composition” or “ink”.

[0077] <Nitrogen-containing aromatic heterocyclic compounds containing tertiary amines>

[0078] In the present invention, the so-called "nitrogen-containing aromatic heterocyclic compound" refers to a nitrogen-containing aromatic heterocyclic ring or a nitrogen-containing heteroaryl group, which is a compound having an aromatic heterocyclic ring containing at least one nitrogen atom as a ring-constituting atom. As atoms constituting the aromatic heterocyclic ring, in addition to carbon and nitrogen, heteroatoms such as oxygen atoms and sulfur atoms may be included.

[0079] Specific examples of the nitrogen-containing aromatic heterocyclic ring include oxazole having a five-membered ring and oxazine having a six-membered ring.

[0080] Specific examples of azoles include pyrrole, isoxazole, isothiazole, pyrazole, imidazole, oxadiazole, and thiadiazole, each having one nitrogen atom. Specific examples of azoles include 1,2,3-triazole, 1,2,4-triazole, and tetrazole, each having four nitrogen atoms.

[0081] Specific examples of the azine include pyridine having one nitrogen atom, pyrimidine, pyrazine, and pyridazine having two nitrogen atoms, and triazine having three nitrogen atoms.

[0082] As the nitrogen-containing aromatic heterocyclic ring, a nitrogen-containing aromatic heterocyclic ring having five members is particularly preferred in terms of improving the anti-discoloration performance at high temperatures over time.

[0083] It is preferred that the benzene ring is not directly fused to the nitrogen-containing aromatic heterocyclic ring in the present invention. Examples of the nitrogen-containing aromatic heterocyclic compound to which the benzene ring is directly fused include quinoline, isoquinoline, indole, benzotriazole, benzimidazole, and the like.

[0084] Examples of the tertiary amine include trimethylamine, triethylamine, N,N-dimethylethylamine, N-methyldi-n-octylamine, bis(2-ethylhexyl)aminomethyl, N,N-bis(2-ethylhexyl)methylamine, and 1-methylpiperazine.

[0085] The nitrogen-containing aromatic heterocyclic compound having a tertiary amine according to the present invention preferably contains a five-membered nitrogen-containing aromatic heterocyclic compound, and particularly preferably contains a triazole compound in terms of improving the anti-discoloration performance at high temperatures over time.

[0086] In addition, from the viewpoint of excellent plating resistance of the solder resist, it is preferred that the triazole compound has a structure represented by the following general formula (a).

[0087]

Chemistry 5

[0088] General formula (a)

[0089]

[0090] In the above general formula (a), Ra and Rb each represent an alkyl group having 1 to 20 carbon atoms. Ra is preferably an alkyl group having 1 to 10 carbon atoms. Rb is preferably an alkyl group having 1 to 10 carbon atoms.

[0091] Examples of the nitrogen-containing aromatic heterocyclic compound having a tertiary amine of the present invention include the following compounds, but the present invention is not limited thereto. The nitrogen-containing aromatic heterocyclic compound having a tertiary amine is preferably the following compounds B-1 to B-7 in which the benzene ring is not directly fused to the nitrogen-containing aromatic heterocyclic ring.

[0092]

Chemistry 6

[0093]

[0094] 1-[N,N-Bis(2-ethylhexyl)aminomethyl]benzotriazole

[0095]

[0096] The content of the nitrogen-containing aromatic heterocyclic compound having a tertiary amine is preferably in the range of 0.05 to 5% by mass, and more preferably in the range of 0.1 to 2.5% by mass, relative to the total mass of the curable composition for inkjet. By making the content of the nitrogen-containing aromatic heterocyclic compound having a tertiary amine within the above range, changes in viscosity, particle size, and anti-discoloration performance at high temperatures over time can be suppressed.

[0097] <Polymerizable compounds>

[0098] The polymerizable compound according to the present invention is a compound that is polymerized and cross-linked by irradiation with active rays. The polymerizable compound may be a compound that is further polymerized and cross-linked by heating after irradiation with active rays.

[0099] Examples of active rays include electron beams, ultraviolet rays, α rays, γ rays, and X-rays, etc. Among these, ultraviolet rays and electron beams are preferred, and ultraviolet rays are more preferred.

[0100] The polymerizable compound may be a cationically polymerizable compound or a radically polymerizable compound, but is preferably a radically polymerizable compound. The radically polymerizable compound is a compound having an ethylenically unsaturated bond that can be radically polymerized.

[0101] The polymerizable compound according to the present invention is preferably a polymerizable compound having a carboxyl group, a hydroxyl group or an epoxy group, from the viewpoint of improving the adhesion between the solder resist and the base material and further improving the effect of suppressing discoloration before and after soldering.

[0102] The reason why the above effect is exerted is not clear, but it is presumed that the carboxyl group, hydroxyl group, or epoxy group also interacts with the substrate, and thus the substrate is more densely covered.

[0103] (Polymerizable compound having a carboxyl group)

[0104] The polymerizable compound having a carboxyl group is preferably a radical polymerizable compound. The radical polymerizable compound may be contained in the ink alone or in combination of two or more.

[0105] Examples of the free radical polymerizable compound having a carboxyl group include (meth)acrylate, (meth) ethyl carboxylate, 2-acryloyloxyethyl phthalate, and 2-acryloyloxyethyl hexahydrophthalate. Among these, the free radical polymerizable compound is preferably (meth)acrylate or carboxyethyl acrylate. The carboxyethyl acrylate is also referred to as "polymerizable compound A-10 containing a carboxyl group" described in the examples.

[0106] In addition, in this specification, "(meth)acrylate" means acrylate or methacrylate, and "(meth)acrylic acid" means acrylic acid or methacrylic acid.

[0107] The polymerizable compound having a carboxyl group may be monofunctional or polyfunctional. From the viewpoint of preventing the adhesiveness from being reduced due to the curing shrinkage of the solder resist, the polymerizable compound having a carboxyl group is preferably a pentafunctional or less compound.

[0108] Furthermore, the polymerizable compound having a carboxyl group has a structure represented by the following general formula (1), and is preferably used because it has a carboxylic acid and thus provides better adhesion between the solder resist and the substrate.

[0109]

Chemistry 7

[0110] General formula (1)

[0111]

[0112] In the above general formula (1), X represents a substituent having at least one selected from the group consisting of acryloyl group, methacryloyl group, allyl group, vinyl group and derivatives thereof at the terminal.

[0113] 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.

[0114] R1 represents an unsubstituted alkylene group having 1 to 6 carbon atoms.

[0115] The compound having the structure represented by general formula (1) has two carbonyl groups (C(=O)) in the molecule via unsubstituted alkylene groups. Thus, two oxygen atoms contained in the two carbonyl groups form coordination bonds with metal atoms, thereby more fully improving the adhesion to the substrate.

[0116] From the viewpoint of making the coordination bond between the above two oxygen atoms and the metal atom more stable and improving the adhesion with the substrate more fully, R1 is preferably an unsubstituted alkylene group having 1 to 6 carbon atoms. From the viewpoint of further improving the above adhesion, R1 is preferably an unsubstituted alkylene group having 1 or 2 carbon atoms. Thus, when the above coordination bond is formed, a ring structure is formed by the metal atom, the above two oxygen atoms and R1 (alkylene group), and the above coordination bond is more stable. From the same viewpoint, Q is preferably an oxygen atom.

[0117] In addition, as for the above-mentioned polymerizable group X has at the end, it is preferably a (meth)acryloyl group. Since the (meth)acryloyl group has high reactivity, it is easy to polymerize and enter the coating film. Therefore, the compound having a (meth)acryloyl group as a polymerizable group can fully exert the effect of improving the adhesion caused by the carboxyl group.

[0118] Examples of the compound having a structure represented by the general formula (1) include the following compounds, but the present invention is not limited to these compounds.

[0119]

Chemistry 8

[0120]

[0121]

Chemistry 9

[0122]

[0123] The polymerizable compound having a carboxyl group may be a monomer or an oligomer, preferably a monomer. It should be noted that in this specification, the term "monomer" refers to a polymerizable compound as a monomer having a molecular weight of less than 700. The molecular weight can be measured by gel permeation chromatography.

[0124] (Polymerizable compound having hydroxyl group)

[0125] The polymerizable compound having a hydroxyl group is not particularly limited as long as it has a hydroxyl group in its structure. Specific examples of the polymerizable compound having a hydroxyl group include hydroxyalkyl (meth)acrylates and hydroxy(meth)acrylates having an alicyclic structure.

[0126] Examples of the hydroxyalkyl (meth)acrylate include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate. 4-Hydroxybutyl (meth)acrylate is the following polymerizable compound A-11 containing a hydroxyl group.

[0127] Moreover, as a hydroxyl (meth)acrylate which has an alicyclic structure, 1, 4- cyclohexanedimethanol mono (meth) acrylate etc. are mentioned, for example.

[0128] In addition, the polymerizable compound having a hydroxyl group can also use epoxy acrylate obtained by reacting (meth) acrylic acid with an epoxy compound. As epoxy acrylate, a commercially available product can be used. As the commercially available product, for example, epoxy ester 70PA (manufactured by Kyoeisha Chemical Co., Ltd.), epoxy ester 200PA (manufactured by Kyoeisha Chemical Co., Ltd.), DENACOL ACRYLATE DA-111 (manufactured by Nagase Chemtex Co., Ltd., etc. Epoxy ester 70PA (manufactured by Kyoeisha Chemical Co., Ltd.) is the following polymerizable compound A-12 containing a hydroxyl group. Among these, epoxy acrylate is preferred. If it is epoxy acrylate, it is preferred in terms of better adhesion between the solder resist and the substrate.

[0129]

Chemistry 10

[0130]

[0131] (Polymerizable compound having epoxy group)

[0132] The polymerizable compound having an epoxy group is not particularly limited as long as it has an epoxy group in its structure. Specific examples of the polymerizable compound having an epoxy group include aliphatic alcohol epoxy, aliphatic polyol epoxy, and phenol epoxy.

[0133] Moreover, as epoxy (meth)acrylate, the following epoxy (meth)acrylates are mentioned, for example.

[0134]

Chemistry 11

[0135]

[0136] In terms of improving the heat resistance of a cured film of a solder resist or the like, the polymerizable compound having a carboxyl group, a hydroxyl group or an epoxy group preferably has any one of a bisphenol structure, a cresol novolac structure or a phenol novolac structure.

[0137] Examples of the bisphenol structure include a bisphenol A type structure and a bisphenol F type structure.

[0138] Examples of the polymerizable compound having any one of a bisphenol structure, a cresol novolac structure, or a phenol novolac structure include the following compounds in addition to the above-mentioned epoxy group-containing polymerizable compound A-22.

[0139]

Chemistry 12

[0140]

[0141] The content of the polymerizable compound is preferably in the range of 20 to 99% by mass, more preferably in the range of 30 to 95% by mass, relative to the total mass of the curable composition for inkjet. By making the content of the polymerizable compound in the above range, the coating film adhesion and hardness are improved in the solder resist and inkjet recording method.

[0142] <Polymerization initiator>

[0143] The polymerization initiator according to the present invention is a compound that initiates polymerization and crosslinking of the above-mentioned polymerizable compound by irradiation with active rays.

[0144] The polymerization initiator can be a free radical polymerization initiator when the ink contains a free radical polymerizable compound, and can be a cationic polymerization initiator when the ink contains a cationic polymerizable compound. Examples of free radical polymerization initiators include intramolecular bond cleavage type free radical polymerization initiators and hydrogen abstraction type free radical polymerization initiators.

[0145] Examples of intramolecular bond cleavage type free radical polymerization initiators include acetophenone-based initiators such as diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropane-1-one, benzyl dimethyl ketal, 1-(4-isopropylphenyl)-2-hydroxy-2-methylpropane-1-one, 4-(2-hydroxyethoxy)phenyl-(2-hydroxy-2-propyl)ketone, 1-hydroxycyclohexyl-phenyl ketone, 2-methyl-2-morpholino(4-methylthiophenyl)propane-1-one, and 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone; benzoin-based initiators such as benzoin, benzoin methyl ether, and benzoin isopropyl ether; acylphosphine oxide-based initiators such as bis-2,4,6-trimethylbenzoin diphenylphosphine oxide, benzyl, and methylphenylglyoxylate, etc.

[0146] Examples of commercially available acetophenone-based initiators include Omnirad 907 (manufactured by IGM) (molecular weight 279) and Omnirad 379 (manufactured by IGM) (molecular weight 381).

[0147] Examples of commercially available acylphosphine-based initiators include Omnirad TPO H (manufactured by IGM) (molecular weight 348) and Omnirad 819 (manufactured by IGM) (molecular weight 419).

[0148] Examples of hydrogen abstraction type free radical polymerization initiators include benzophenone, methyl o-benzoylbenzoate, 4-phenylbenzophenone, 4,4'-dichlorobenzophenone, hydroxybenzophenone, 4-benzoyl-4'-methyl-diphenyl sulfide, acrylated benzophenone, 3,3',4,4'-tetra(tert-butylperoxycarbonyl)benzophenone, and 3,3'-dimethyl-4-methoxybenzophenone; thioxanthone initiators such as 2-isopropylthioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, and 2,4-dichlorothioxanthone; aminobenzophenone initiators such as Michler's ketone and 4,4'-diethylaminobenzophenone, 10-butyl-2-chloroacridone, 2-ethylanthraquinone, 9,10-phenanthrenequinone, and camphorquinone.

[0149] Examples of commercially available thioxanthone-based initiators include 2-isopropylthioxanthone (Speedcure ITX (manufactured by Speedcure Inc.) (molecular weight 254)) and 2,4-diethylthioxanthone (Speedcure DETX (manufactured by Speedcure Inc.) (molecular weight 268)).

[0150] Examples of the cationic polymerization initiator include a photoacid generator.

[0151] Examples of the photoacid generator include B(C6F5)4 containing aromatic onium compounds such as diazo, ammonium, iodonium, sulfonium, and phosphonium. - PF6 - 、AsF6 - 、SbF6 - CF3SO3 - salts, sulfonates that generate sulfonic acids, halides that generate hydrogen halides, and iron arene complexes.

[0152] As the polymerization initiator according to the present invention, thioxanthone is preferably used in order to improve the plating resistance of the solder resist.

[0153] The content of the polymerization initiator is preferably in the range of 1 to 10% by mass, more preferably in the range of 2 to 8% by mass, based on the total mass of the curable composition for inkjet.

[0154] <Gelling agent>

[0155] The curable composition for inkjet of the present invention may contain a gelling agent.

[0156] The gelling agent makes the ink sol under heating and gels at room temperature. Thus, the heated and sol ink is discharged from the inkjet head and falls on the recording medium, and the cooled and gelled ink is temporarily solidified, which can improve the pinning property of the ink. Thus, the wetting and spreading of the ink is suppressed, and adjacent dots are less likely to become the same dot, so that a higher-definition pattern can be formed.

[0157] In addition, since the curable composition for inkjet includes a gelling agent, the hydrophobicity of the solder resist formed is improved, and thus water absorption of the solder resist can be further suppressed. Thus, ion migration in a high humidity environment is further suppressed, and the reduction in the insulation properties of the solder resist can be fully suppressed.

[0158] The gelling agent is preferably a compound that dissolves in the polymerizable compound contained in the ink at a temperature higher than the gelling temperature of the ink and crystallizes in the ink at a temperature lower than the gelling temperature of the ink.

[0159] Here, the so-called "gelation temperature" refers to the temperature at which the ink changes from a sol phase to a gel and the viscosity of the ink changes rapidly when the above-mentioned ink that has been solified or liquefied by heating is cooled. Specifically, the viscosity of the solified or liquefied ink can be measured while cooling using a rheometer (e.g., MCR300 manufactured by Anton Paar), and the temperature at which the viscosity rises rapidly is defined as the gelation temperature of the ink.

[0160] The gelling agent preferably crystallizes in the ink at a temperature below the gelling temperature of the ink, and the crystallized plate-shaped gelling agent forms a structure in which the radical polymerizable compound is enclosed in the formed three-dimensional space. Such a structure is hereinafter referred to as a "card house structure". If the card house structure is formed, the liquid active radiation polymerizable compound is retained in the above space. Therefore, the dots formed by the ink adhering to the recording medium are more difficult to wet and spread, and the pinning property of the ink is further improved. As a result, it becomes difficult for the dots formed by the ink adhering to the recording medium to be aligned.

[0161] Examples of gelling agents that can more easily form a cell-like structure generated by crystallization include aliphatic ketones, aliphatic esters, petroleum waxes, plant waxes, animal waxes, and mineral waxes. In addition, examples of the above-mentioned gelling agents include solidified castor oil, modified waxes, higher fatty acids, higher alcohols, hydroxystearic acid, and fatty acid amides including N-substituted fatty acid amides and special fatty acid amides. Furthermore, examples of the above-mentioned gelling agents include higher amines, esters of sucrose fatty acids, synthetic waxes, dibenzylidene sorbitol, dimer acids, and dimer diols.

[0162] Examples of aliphatic ketones include di(tetracosyl)ketone, di(docosyl)ketone, di(octadecyl)ketone, di(eicosyl)ketone, di(palmityl)ketone, di(lauryl)ketone, di(myristyl)ketone, myristylpalmitylketone and palmitylstearylketone.

[0163] Examples of aliphatic esters include fatty acid esters of monohydric alcohols such as behenyl behenate, eicosyl eicosate, stearyl stearate, palmityl stearate, myristyl myristate, cetyl myristate, and oleyl palmitate; and fatty acid esters of polyhydric alcohols such as glycerol fatty acid esters, sorbitan fatty acid esters, propylene glycol fatty acid esters, ethylene glycol fatty acid esters, and polyoxyethylene fatty acid esters.

[0164] Examples of commercially available products of the above-mentioned aliphatic esters include the Emalex series (manufactured by Nippon Emergent Co., Ltd. ("EMALEX" is a registered trademark of the company)), the Richemal series, and the Poem series (manufactured by Riken Vitamin Co., Ltd.). Both "Richemal" and "Poem" are registered trademarks of Riken Vitamin Co., Ltd.

[0165] Examples of higher fatty acids include behenic acid, arachidic acid, stearic acid, palmitic acid, myristic acid, lauric acid, oleic acid, and erucic acid.

[0166] Examples of the higher alcohol include stearyl alcohol and behenyl alcohol.

[0167] Among these, from the viewpoint of further improving the pinning property, the gelling agent is preferably an aliphatic ketone, an aliphatic ester, a higher fatty acid, and a higher alcohol. The gelling agent is more preferably an aliphatic ketone represented by the following general formula (G1) or an aliphatic ester represented by the following general formula (G2). The gelling agent may contain only one kind or a combination of two or more kinds.

[0168] General formula (G1): R a -CO-R b

[0169] General formula (G2): R c -COO-R d

[0170] In the general formula (G1), R a and R b Each of the groups independently represents a linear hydrocarbon group having 12 to 26 carbon atoms and which may have a branch.

[0171] In the general formula (G2), R c and R d Each of the groups independently represents a linear hydrocarbon group having 12 to 26 carbon atoms and which may have a branch.

[0172] In the general formulas (G1) and (G2), R a ~R d The carbon number of the carbon atoms is 12 or more, and the crystallinity of the gelling agent represented by the general formula (G1) and (G2) is further improved. Furthermore, a more sufficient space is generated in the card room structure. Therefore, the polymerizable compound is easily and fully enclosed in the space, and the pinning property of the ink is improved.

[0173] In addition, through R a ~R d The carbon number of the compound is 26 or less, which can suppress the melting point of the gelling agent represented by the general formula (G1) and the general formula (G2) from rising excessively. As a result, the solubilization temperature of the ink containing the gelling agent does not rise excessively, and the heating temperature of the ink can be lowered to discharge the ink.

[0174] Examples of aliphatic ketones represented by the general formula (G1) include di(tetracosyl) ketone (carbon number: 23-24), dibehenyl ketone (carbon number: 21-22), distearyl ketone (carbon number: 17-18), di(eicosyl) ketone (carbon number: 19-20), dipalmityl ketone (carbon number: 15-16), dimyristyl ketone (carbon number: 13-14), dilauryl ketone (carbon number: 15-16), dioctyl ketone (carbon number: 13-14 ... 11-12), lauryl myristyl ketone (carbon number: 11-14), lauryl palmityl ketone (11-16), myristyl palmityl ketone (13-16), myristyl stearyl ketone (13-18), myristyl behenyl ketone (13-22), palmityl stearyl ketone (15-18), palmityl behenyl ketone (15-22) and stearyl behenyl ketone (17-22). The carbon numbers in the above parentheses represent the carbon numbers of the two hydrocarbon groups separated by the carbonyl group.

[0175] Examples of commercially available products of the compound represented by the general formula (G1) include 18-pentatriacontanon and hentriactan-16-on (both manufactured by Alfa Aeser), and KAOWAX T1 (manufactured by Kao Corporation).

[0176] Examples of the aliphatic ester represented by the general formula (G2) include behenyl behenate (carbon number: 21-22), eicosyl eicosate (carbon number: 19-20), stearyl stearate (carbon number: 17-18), palmityl stearate (carbon number: 17-16), lauryl stearate (carbon number: 17-12), cetyl palmitate (carbon number: 15-16), stearyl palmitate (carbon number: 15-18) , myristyl myristate (carbon number: 13-14), cetyl myristate (carbon number: 13-16), octyldodecyl myristate (carbon number: 13-20), stearyl oleate (carbon number: 17-18), stearyl erucate (carbon number: 21-18), stearyl linoleate (carbon number: 17-18), behenyl oleate (carbon number: 18-22), and arachidyl linoleate (carbon number: 17-20), etc. The carbon numbers in the above parentheses represent the carbon numbers of the two hydrocarbon groups separated by the ester group.

[0177] Examples of commercially available products of the aliphatic ester represented by the general formula (G2) include UNISTAR M-2222SL, SPAM ACETI, NISSAN ELECTRO WEP-2 and NISSAN ELECTRO WEP-3 (all manufactured by NOF Corporation, “UNISTAR” and “NISSAN ELECTRO” are registered trademarks of the company), ICEPAR SS and ICEPAR MY-M (all manufactured by Kao Corporation, “ICEPAR” 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 Amrepus PC (manufactured by Advanced Alcohol Industries, Ltd., "Amrepus" is a registered trademark of the company), etc. Most of these commercial products are mixtures of two or more, so they can be separated and purified as needed so that they can be contained in the ink.

[0178] The content of the gelling agent is preferably 1 to 10% by mass, more preferably 1 to 5% by mass, relative to the total mass of the curable composition for inkjet. When the content is 1% by mass or more, water absorption of the solder resist can be further suppressed, and the reduction of insulation properties under high humidity environments can be further suppressed. When the content is 10% by mass or less, the solubility of the gelling agent in the polymerizable compound can be further improved.

[0179] <Other>

[0180] The curable composition for inkjet of the present invention contains a pigment as a colorant within a range in which the effects of the present invention are exerted.

[0181] (Colorant)

[0182] The colorant is a dye or a pigment, and a pigment is preferred from the viewpoint of improving the heat resistance of the colorant and preventing discoloration of a cured film of the composition after aging at high temperatures.

[0183] The pigment can be selected from, for example, yellow pigment, red pigment, cyan pigment, black pigment, and white pigment, depending on the color of an image to be formed.

[0184] Examples of yellow pigments include Pigment Yellow (PY) 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. Among these, PY185 and PY150 are preferred from the viewpoint of improving the heat resistance of the pigment and preventing discoloration of the cured film.

[0185] Examples of red pigments include Pigment Red (PR) 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 (PV) 3, 19, 23, 29, 30, 37, 50, 88, Pigment Orange (PO) 13, 16, 20, 36, and the like. Among these, PR122 and PV19 are preferred from the viewpoint of improving the heat resistance of the pigment and preventing discoloration of the cured film.

[0186] Examples of cyan pigments include Pigment Blue (PB) 1, 15, 15:1, 15:2, 15:3, 15:4, 15:6, 16, 17:1, 22, 27, 28, 29, 36, 60, etc. Among these, PB15:3 and PB15:4 are preferred from the viewpoint of improving the heat resistance of the pigment and preventing discoloration of the cured film.

[0187] Examples of green pigments include CI Pigment Green 7, PG26, PG36, and PG50. "PG" is CI Pigment Green.

[0188] Examples of black pigments include CI Pigment Black 7, PBk26, and PBk28. "PBk" is CI Pigment Black.

[0189] As for the white pigment, any pigment can be used as long as the cured film formed by curing the white ink is white. Examples of white pigments include inorganic pigments such as titanium oxide, zinc oxide, calcium carbonate, barium sulfate, and aluminum hydroxide. Among these, titanium oxide is preferred.

[0190] As for the crystal form of the titanium oxide, rutile, anatase and brookite are all possible. From the viewpoint of making the white pigment smaller in particle size, anatase with a small specific gravity is preferred. In addition, from the viewpoint of further improving the concealment of the formed image, the crystal form is preferably rutile with a large refractive index in the visible light region.

[0191] The content of the colorant is preferably 0.1 to 10% by mass, more preferably 0.3 to 5% by mass, relative to the total mass of the curable composition. When the colorant is a pigment, from the viewpoint of reducing the amount of impurities in the curable composition, the content of the pigment is preferably 20% by mass or less, more preferably 10% by mass or less, relative to the total mass of the curable composition.

[0192] (Synthetic agent)

[0193] The curable composition for inkjet of the present invention may contain a synergist.

[0194] The synergist is a compound having an anchoring part adsorbed on the pigment and a polar part adsorbed on the pigment dispersant. In the case of the synergist, in the ink, the anchoring part is adsorbed on the pigment, and the polar part is adsorbed on the pigment dispersant. Therefore, the pigment dispersant can be attached to the pigment via the synergist, and becomes difficult to dissociate from the pigment. Thus, the dispersion stability of the ink can be further improved.

[0195] Furthermore, as a result of the present inventors' studies, it was found that when the amine value of the pigment dispersant contained in the ink is higher than the acid value, the dispersion stability of the ink is significantly improved by including a synergist.

[0196] Examples of synergists include pigment derivatives. The so-called pigment derivatives are compounds in which polar groups are introduced into the pigment that serves as the parent core. That is, in the case of the pigment derivative, the pigment that serves as the parent core serves as the anchor part, and the polar group serves as the polar part.

[0197] Examples of the polar group include chloro, sulfonyl, sulfonylamino, carboxyl, carboxylamino, amino, acylamino, aminomethyl, imido, imidomethyl, phthalimido, phthalimidomethyl, nitro, cyano, phosphoric acid, etc. Among these, carboxyl, sulfonyl, nitro, phosphoric acid, amino and acylamino are preferred.

[0198] Examples of the pigment derivative include azo derivatives, quinoline derivatives, pyrazole derivatives, and the like.

[0199] The synthesis method of the pigment derivative is not particularly limited. For example, when a sulfonyl group is introduced as a polar group into an azo pigment, fuming sulfuric acid, concentrated sulfuric acid, etc. are added to a solution in which the pigment is dispersed, and the solution is heated to a temperature in the range of 60 to 200° C. and stirred. Then, by removing the volatile components, a pigment in which a sulfonyl group is introduced into the azo pigment can be obtained.

[0200] Examples of commercially available products of the pigment derivative include Solsperse 5000S, Solsperse 12000S, and Solsperse 22000 (manufactured by Lubrizol Corporation).

[0201] The synergist may be an aqueous dye having an acidic group or a basic group.

[0202] Examples of the acidic group include a carboxyl group, a sulfonyl group, and a phosphoric acid group, etc. Among these, a sulfonyl group is preferred.

[0203] Examples of the above-mentioned basic group include an amino group and an imino group.

[0204] Examples of the water-based dye include CI Acid Yellow 3, CI Acid Yellow 11, CI Acid Yellow 23, and Direct Red 21.

[0205] The content of the synergist is preferably in the range of 1 to 10% by mass, more preferably in the range of 2 to 8% by mass, relative to the total mass of the pigment. If it is 1% by mass or more, the dispersion stability of the ink can be further improved. If it is 10% by mass or less, the proportion of the pigment can be increased, and the color change of the cured film can be further suppressed.

[0206] (Pigment dispersant)

[0207] When the ink of the present invention contains a pigment, the ink may contain a pigment dispersant.

[0208] Examples of pigment dispersants include carboxylates having a hydroxyl 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, naphthalenesulfonic acid formalin condensate salts, aromatic sulfonic acid formalin condensate salts, polyoxyethylene alkyl phosphates, polyoxyethylene nonylphenyl ethers, and stearylamine acetate.

[0209] Examples of commercially available pigment dispersants include Solsperse (registered trademark) series manufactured by Avecia, Inc. and PB series manufactured by Ajinomoto Ficinno Co., Ltd.

[0210] The content of the pigment dispersant is preferably within a range of 1 to 50% by mass relative to the mass of the pigment.

[0211] The pigment dispersant may have an acid value and an amine value. It is particularly preferred that the amine value is larger than the acid value, and the acid value is 20 mg / KOH or less. This can improve the dispersion stability of the pigment dispersant ink.

[0212] Examples of pigment dispersants having an amine value greater than an acid value include BYK-JET-9151 (manufactured by Bick Chemie Co., Ltd.) and EFKA7701 (manufactured by BASF Corporation). The ink may contain only one type of the pigment dispersant or two or more types thereof may be contained in combination.

[0213] The acid value of the pigment dispersant is preferably 20 mg / KOH or less, and more preferably 10 mg / KOH or less. The lower limit of the acid value is not particularly limited, and can be 0 mg / KOH or more.

[0214] The amine value of the pigment dispersant can be greater than the acid value, and is preferably 10 mg / KOH or more, more preferably 20 mg / KOH or more, from the viewpoint of further improving the dispersion stability of the ink. The upper limit of the amine value is not particularly limited, and can be, for example, 60 mg / KOH or less.

[0215] From the viewpoint of further improving the dispersion stability of the ink, the difference between the amine value and the acid value of the pigment dispersant is preferably within a range of 1 to 40 mg / KOH, and more preferably within a range of 10 to 40 mg / KOH.

[0216] The acid value and amine value can be measured by potentiometric titration, for example, by the method described in Journal of Color Materials Association 61,

[12] 692-698 (1988).

[0217] The acid value is determined from the amount of the solution required for neutralization of a solution prepared by dissolving 1 g of the pigment dispersant in 100 mL of methyl isobutyl ketone (MIBK) using a 0.01 mol / L potassium methoxide-methyl isobutyl ketone / methanol (volume ratio 4:1) solution.

[0218] The amine value is determined from the amount of perchloric acid MIBK solution required for neutralization of a solution prepared by dissolving 1 g of the pigment dispersant in 100 mL of methyl isobutyl ketone (MIBK) using a 0.01 mol / L perchloric acid MIBK solution.

[0219] (Surfactant)

[0220] The curable composition for inkjet of the present invention may contain a surfactant.

[0221] Examples of the surfactant include anionic surfactants such as dialkyl sulfosuccinates, alkylnaphthalene sulfonates, and fatty acid salts.

[0222] Examples of the surfactant include nonionic surfactants such as polyoxyethylene alkyl ethers, polyoxyethylene alkyl allyl ethers, acetylene glycols, and polyoxyethylene-polyoxypropylene block copolymers.

[0223] Examples of surfactants include cationic surfactants such as alkylamine salts and quaternary ammonium salts, and silicone-based and fluorine-based surfactants.

[0224] Examples of commercially available silicone surfactants include 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 Big Chemie Co., Ltd. ("BYK" is a registered trademark of the company)), and TSF4452 (manufactured by Momentive Parts Materials Co., Ltd.).

[0225] Examples of commercially available fluorine-based surfactants include Megafac F (manufactured by DIC Corporation (“Megafac” is a registered trademark of the company)), Surflon (manufactured by AGC Seikaru Co., Ltd. (“Surflon” is a registered trademark of the company)), Fluorad FC (manufactured by 3M Co. (“Fluorad” is a registered trademark of the company)), Monflor (manufactured by Inperial Chemikar Industrie Co., Ltd.), Zonyls (manufactured by I-I-D Upom Nemeras Ando Canpany Co., Ltd.), Licowet VPF (manufactured by Lubebelke Hector Co., Ltd.) and FTERGENT (manufactured by Neos Co., Ltd. ("FTERGENT" is a registered trademark of the company)), etc.

[0226] The content of the surfactant relative to the total mass of the curable composition is not particularly limited within a range in which the effects of the present invention are exhibited, and can be, for example, 0.001 mass % or more and less than 1.0 mass %.

[0227] (Inhibitor)

[0228] The inkjet curable composition of the present invention preferably further contains a radical polymerization inhibitor from the viewpoint of storage stability.

[0229] Examples of the radical polymerization inhibitor include compounds containing a phenolic hydroxyl group, quinones or hydroquinones, phenothiazines, N-oxyls, and nitrosoamines.

[0230] From the viewpoint of improving the storage stability at higher temperatures and the anti-discoloration performance, the radical polymerization inhibitor is preferably an N-oxyl group or a nitrosoamine group.

[0231] Examples of the above-mentioned compounds containing phenolic hydroxyl groups 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-tert-butyl-p-cresol (butylated hydroxytoluene: BHT), 4-methoxyphenol, and 2-methoxy-4-methylphenol.

[0232] Examples of the quinones or hydroquinones include hydroquinone, methoxyhydroquinone, benzoquinone, 1,4-naphthoquinone, p-tert-butylcatechol, hydroquinone monomethyl ether (MEHQ), and the like.

[0233] As the above-mentioned N-oxyls (nitrogenoxy- or N-oxy-based compounds having at least one >NO-group), for example, piperidine N-oxyl compounds are preferred, and free radical compounds of piperidine N-oxyl are preferred.

[0234] Among the examples of the above-mentioned N-oxyls, 4-hydroxy-2,2,6,6-tetramethyl-piperidin-N-oxyl, 4-oxo-2,2,6,6-tetramethyl-piperidin-N-oxyl, 4-methoxy-2,2,6,6-tetramethyl-piperidin-N-oxyl, 4-acetoxy-2,2,6,6-tetramethyl-piperidin-N-oxyl, 2,2,6,6-tetramethyl-piperidin-N-oxyl, BASF Uvinul 4040P from Aktiengesellschaft, 4,4',4"-tris-(2,2,6,6-tetramethyl-piperidin-N-oxy)phosphite, 3-oxo-2,2,5,5-tetramethyl-pyrrolidine-N-oxyl, 1-oxy-2,2,6,6-tetramethyl-4-methoxypiperidine, 1-oxy-2,2,6,6-tetramethyl-4-trimethylsilyloxypiperidine, 1-oxy-2,2,6,6-tetramethylpiperidin-4-yl-2-ethylhexanoate, 1-oxy-2,2,6,6-tetramethyl piperidin-4-yl-sebacate, 1-oxy-2,2,6,6-tetramethylpiperidin-4-yl-stearate, 1-oxy-2,2,6,6-tetramethylpiperidin-4-yl-benzoate, 1-oxy-2,2,6,6-tetramethylpiperidin-4-yl-(4-tert-butyl)benzoate, bis-(1-oxy-2,2,6,6-tetramethylpiperidin-4-yl)succinate, bis-(1-oxy-2,2,6,6-tetramethylpiperidin-4-yl)adipate, 1,10-sebacate-bis-(1-oxy-2,2,6,6-tetramethylpiperidin-4-yl)ester, Bis-(1-oxy-2,2,6,6-tetramethylpiperidin-4-yl) n-butylmalonate, bis-(1-oxy-2,2,6,6-tetramethylpiperidin-4-yl) o-phthalate, bis-(1-oxy-2,2,6,6-tetramethylpiperidin-4-yl) isophthalate, bis-(1-oxy-2,2,6,6-tetramethylpiperidin-4-yl) terephthalate, bis-(1-oxy-2,2,6,6-tetramethylpiperidin-4-yl) hexahydroterephthalate, N,N'-bis-(1-oxy-2,2,6,6-tetramethylpiperidin-4-yl) hexahydroterephthalate amide, N-(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl)caprolactam, N-(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl)dodecylsuccinimide, 2,4,6-tri-[N-butyl-N-(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl]triazine, N,N'-bis-(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl)-N,N'-bis-formyl-1,6-diaminohexane, 4,4'-ethylene-bis-(1-oxyl-2,2,6,6-tetramethylpiperazin-3-one).

[0235] Moreover, as an example of the commercially available product of an N-oxyl type, Irgastab UV-10 (made by BASF Japan Ltd.) can be mentioned.

[0236] Examples of the above-mentioned nitrosoamines include salts of N-nitrosophenylhydroxylamine and the like.

[0237] Examples of the salt of N-nitrosophenylhydroxylamine include N-nitrosophenylhydroxylamine ammonium salt and N-nitroso-N-phenylhydroxylamine aluminum (NPHA).

[0238] The amount of each polymerization inhibitor is not particularly limited, and the content of each polymerization inhibitor is preferably within a range of 0.01 to 1% by mass based on 100% by mass of the curable composition for inkjet.

[0239] (Antioxidant)

[0240] The curable composition for inkjet of the present invention may contain an antioxidant in order to further enhance the anti-discoloration effect of the coating film.

[0241] As the above antioxidant, there are n-octadecyl-3-(3'5'-di-tert-butyl-4'-hydroxyphenyl)-propionate, n-octadecyl-3-(3'-methyl-5'-tert-butyl-4'-hydroxyphenyl)-propionate, n-tetradecyl-3-(3'5'-di-tert-butyl-4'-hydroxyphenyl)-propionate, 1,6-hexanediol-bis-(3-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionate), 1,4-butanediol-bis-(3-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionate, hydroxyphenyl)-propionate), triethylene glycol-bis-(3-(3-tert-butyl-5-methyl-4-hydroxyphenyl)-propionate), tetrakis-(methylene-3-(3',5'-di-tert-butyl-4'-hydroxyphenyl) propionate methane, 3,9-bis(2-(3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionyloxy)-1,1-dimethylethyl)2,4,8,10-tetraoxaspiro(5,5)undecane, N,N'-bis-3-(3',5'-di-tert-butyl-4-hydroxyphenyl)propionate Hindered phenol compounds such as hexamethylenediamine, N,N'-tetramethylenebis-3-(3'-methyl-5'-tert-butyl-4-hydroxyphenol)propionyldiamine, N,N'-bis-(3-(3,5-di-tert-butyl-4-hydroxyphenol)propionyl)hydrazine, N-salicyloyl-N'-salicylidenehydrazine, 3-(N-salicyloyl)amino-1,2,4-triazole, N,N'-bis(2-(3-(3,5-di-butyl-4-hydroxyphenyl)propionyloxy)ethyl)oxyamide, di( 3,3'-thiodipropionate, dioctadecyl-3,3'-thiodipropionate, ditridecyl-3,3'-thiodipropionate, pentaerythritol tetrakis(3-dodecylthiopropionate), pentaerythritol tetrakis(3-tetradecylthiopropionate), pentaerythritol tetrakis(3-tridecylthiopropionate), dilauryl-3,3-thiodipropionate, dimyristyl-3,3-thiodipropionate, distearyl-3,Sulfur-based antioxidants such as 3-thiodipropionate, pentaerythritol tetra(3-laurylthiodipropionate, 2-mercaptobenzimidazole, lauryl stearylthiodipropionate, zinc salt of 2-mercaptomethylbenzimidazole, zinc salt of 2-mercaptobenzimidazole, 2-mercaptomethylbenzimidazole, zinc dibutylthiocarbamate, triphenyl phosphite, tri(methylphenyl) phosphite, tri(isooctyl) phosphite, tridecyl phosphite, tri(2-ethylhexyl) phosphite, tri(nonylphenyl) phosphite, tri(octylphenyl) phosphite, tris[decylpoly(oxyethylene)] phosphite, tris(cyclohexylphenyl) phosphite, tricyclohexyl phosphite, tri(decyl) thiophosphite, tri(isodecyl) thiophosphite, phenyl bis(2-ethylhexyl) phosphite, phenyl diiso Phosphorus-based antioxidants such as decyl ester, tetradecyl poly(oxyethylene) phosphite bis(ethylphenyl) ester, phenyl dicyclohexyl phosphite, phenyl diisooctyl phosphite, phenyl ditridecyl phosphite, diphenyl cyclohexyl phosphite, diphenyl isooctyl phosphite, diphenyl 2-ethylhexyl phosphite, diphenyl isodecyl phosphite, diphenyl cyclohexylphenyl phosphite, diphenyl (tridecyl) thiophosphite, and aromatic amine-based antioxidants such as phenylnaphthylamine, 4,4'-dimethoxydiphenylamine, 4,4'-bis(α,α-dimethylbenzyl)diphenylamine, di-tert-butyldiphenylamine, N,N'-di(octylphenyl)amine, 4-isopropoxydiphenylamine, and N,N'-di(2-naphthyl)-p-phenylenediamine.

[0242] These antioxidants may be selected from one or more species or may be used in combination. Among them, hindered phenol compounds are preferred because they have a high discoloration suppressing effect.

[0243] Trade names of hindered phenol compound antioxidants include Irganox 245, Irganox 259, Irganox 565, Irganox 1010, Irganox 1035, Irganox 1076, Irganox 1081, Irganox 1098, Irganox 1222, Irganox 1330, and Irganox 1425WL (all manufactured by BASF).

[0244] The amount of the antioxidant is preferably 0.1 to 5 parts by mass, more preferably 0.2 to 3 parts by mass, relative to 100 parts by mass of the ink. When the amount of the antioxidant is 0.1 parts by mass or more relative to 100 parts by mass of the ink, the effect of preventing discoloration of the coating is large. In addition, when the amount of the antioxidant is 5 parts by mass or less relative to 100 parts by mass of the ink, the storage stability of the ink and the adhesion of the coating become good.

[0245] (Deodorants, fragrances)

[0246] The curable composition for inkjet of the present invention preferably further contains a deodorant or a fragrance from the viewpoint of suppressing the odor of the ink and the odor generated when the cured film is heated.

[0247] The deodorant that can be used in the present invention is not particularly limited, but a deodorant chemically bonded to an amine or an aldehyde is preferred.

[0248] Examples of deodorants chemically bonded to amines include sarcosine compounds such as N-oleoylsarcosine, and examples of deodorants chemically bonded to aldehydes include hydrazide compounds such as Chemcat P-9600 and Chemcat T-6900 (Otsuka Chemical).

[0249] As the fragrance|flavor which can be used in this invention, the following fragrance|flavor|flavor can be mentioned.

[0250] (1) Essential oils such as grapefruit oil, orange oil, lemon oil, lime oil, nutmeg oil, acacia oil, lavender oil, cypress oil, fennel oil, ylang ylang oil, chamomile oil, jasmine oil, cypress oil, peppermint oil, lavender oil, and rosemary oil.

[0251] (2) Alcohols such as hexanol, phenylethyl alcohol (rose P), furfuryl alcohol, methylcyclopentenolone, geraniol, linalool, 1-menthol, borneol, ranbachol, hexanol, methylcyclopentenolone, maltol, eugenol, and α-phenylethyl alcohol.

[0252] (3) Aldehydes such as tetradecanal, hexadecanal, octadecanal, benzaldehyde, and furfural.

[0253] (4) Aldehydes such as ethyl acetoacetate, propyl acetate, amyl acetate, linalyl acetate, benzyl acetate, dimethylbenzylcarbitol acetate, benzyl propionate, heptanal, octanal, dodecanal, citral, lyral, cynarin aldehyde, and vanillin.

[0254] (5) Aromatic compounds such as nootkatone, ethylpyrazine, terpene-free lemon oil, terpene-free orange oil, vanillin, ethyl vanillin, furfurylthiol, borneol and heliotrope, vanillin, and ethyl vanillin.

[0255] (6) Esters such as ethyl acetate (ethyl acetate), propyl acetate (propyl acetate), amyl acetate, linalyl acetate, benzyl acetate (benzyl acetate), dimethylbenzylcarbitol acetate, benzyl propionate, and citronellal acetate.

[0256] Among these, linalool, vanillin and ethyl vanillin are preferred.

[0257] In the present invention, various blended spices obtained by appropriately combining the above-mentioned spices, for example, banana spices, blueberry spices, vanilla spices, mint spices, apple spices, peach spices, melon spices, pineapple spices, grape spices, clove spices, jasmine spices, etc., can also be used as a formula.

[0258] In addition, various blended flavors with commercially available formulas can also be used, for example, vanilla flavor (vanilla BVK-3359 (manufactured by Takasago Flavor Co., Ltd.)), mint flavor (mint THP-8148 (manufactured by Hasegawa Flavor Co., Ltd.)), banana flavor (banana T-1510 (manufactured by Yamamoto Flavor Co., Ltd.)), blueberry flavor (blueberry V-647 (manufactured by Yamamoto Flavor Co., Ltd.)), anise oil N-3707 (manufactured by Takasago Flavor Co., Ltd.), etc. can also be used.

[0259] The content of these spices is 0.01 to 10% by mass, preferably 0.01 to 5% by mass, relative to the total amount of ink. If the content of these spices is 0.01% by mass or more, the fragrance can be felt, and if it is 10% by mass or less, it does not affect the curability and is preferred.

[0260] [physical properties]

[0261] When the inkjet curable composition does not contain a gelling agent, the viscosity of the curable composition at 40° C. is preferably 7 to 15 mPa·s, more preferably 8 to 13 mPa·s. When the viscosity is within the above range, the ejection stability of the ink can be further improved.

[0262] When the curable composition contains a gelling agent, the viscosity of the curable composition at 80° C. is preferably 3 to 20 mPa·s, more preferably 7 to 9 mPa·s, from the viewpoint of further improving the ejectability from an inkjet head.

[0263] When the curable composition contains a gelling agent, the curable composition preferably undergoes a sol-gel phase transition at a temperature of 40° C. or higher and lower than 100° C.

[0264] In addition, the gelling temperature of the curable composition is preferably 40 to 70° C. If the gelling temperature of the curable composition is 40° C. or higher, the ink gels quickly after being dropped on the recording medium, thereby further improving the pinning property. If the gelling temperature of the ink is 70° C. or lower, the ink is difficult to gel when ejected from an inkjet head whose ink temperature is generally around 80° C., thereby enabling the ink to be ejected more stably.

[0265] The viscosity at 40°C, the viscosity at 80°C and the gelling temperature of the ink can be determined by measuring the temperature change of the dynamic viscoelasticity of the ink using a rheometer. Examples of the rheometer include stress-controlled rheometers such as Physica MCR series (manufactured by Anton Paar).

[0266] Specifically, the ink is heated to 100°C and cooled to 25°C under the conditions of a shear rate of 11.7 (1 / s) and a temperature drop rate of 0.1°C / s to obtain a temperature change curve of the viscosity. Then, the viscosity at 40°C and the viscosity at 80°C can be obtained by reading the viscosity at 40°C and 80°C in the temperature change curve of the viscosity, respectively. The gelling temperature can be obtained as the temperature at which the viscosity reaches 200 mPa·s in the temperature change curve of the viscosity.

[0267] [Method for preparing inkjet curable composition]

[0268] The inkjet curable composition according to the present invention can be prepared by mixing the above-mentioned components. In order to improve the solubility of each component, it is preferable to mix while heating.

[0269] It should be noted that a pigment dispersion containing a pigment and a pigment dispersant is prepared in advance, and the remaining components may be added thereto and mixed. In this case, the pigment may be dispersed by, for example, a ball mill, a sand mill, an attritor, a roll mill, a stirrer, a Henschel mixer, a colloid mill, an ultrasonic homogenizer, a bead mill, a wet jet mill, and a paint shaker.

[0270] As for the curable composition for inkjet, it can be used for the formation of solder resist (insulating film) for electronic components. Therefore, as for the above-mentioned curable composition, for example, it can be used as a solder resist ink for forming a solder resist on a printed wiring substrate, and an ink for forming a solder resist in a semiconductor IC package and an RFID antenna. In addition, as for the above-mentioned curable composition, it can also be used for semiconductor sealant ink, bottom filling material ink, patch material ink, LED, image display device black matrix ink, multilayer substrate prepreg ink, etc.

[0271] [Inkjet recording method]

[0272] The inkjet recording method of the present invention is an inkjet recording method in which a curable inkjet composition is discharged onto a substrate and cured by active radiation, and is characterized in that the curable inkjet composition of the present invention is used and a substrate containing metal is used as the substrate.

[0273] Specifically, the inkjet recording method of the present invention comprises: a step of applying the above-mentioned curable composition for inkjet to the surface of a substrate; and a step of irradiating the applied curable composition with active rays to cure the curable composition.

[0274] (1) Ink application process

[0275] In this step, the curable composition for inkjet of the present invention is applied to a substrate by an inkjet method.

[0276] As for the discharge method from the inkjet head, both an on-demand method and a continuous method are possible.

[0277] As for the inkjet head of the on-demand method, electro-mechanical conversion methods such as single-chamber type, dual-chamber type, inkjet type, piston type, shared pattern type and shared wall type, and electro-thermal conversion methods such as thermal inkjet type and bubble jet type are all possible. "BubbleJet" is a registered trademark of Canon Inc.

[0278] The ink is preferably heated so that the temperature of the ink when filling the inkjet head is 40° C. or higher. In particular, the temperature of the ink is preferably set to 40 to 100° C., more preferably 40 to 90° C. By setting the ink temperature to the above, the discharge performance from the inkjet head can be further improved.

[0279] In particular, when the ink contains a gelling agent, the ink droplets are heated and discharged from the inkjet head in a sol state. Therefore, the temperature of the ink when filling the inkjet head is preferably set to be above the gelling temperature of the ink + 10°C and below the gelling temperature + 30°C.

[0280] If the temperature of the active radiation curable ink in the inkjet head is above the gelling temperature + 10°C, the ink gelling in the inkjet head or on the nozzle surface will not easily cause a reduction in discharge performance. On the other hand, if the temperature of the ink in the inkjet head is below the gelling temperature + 30°C, the components will not easily deteriorate due to high temperature.

[0281] There is no particular limitation on the method for heating the ink. For example, at least one of the ink supply system such as the ink tank constituting the head box, the supply pipe, the ink tank in the front chamber in front of the head, the pipe with the filter, and the piezoelectric head can be heated by a panel heater, a belt heater, or warm water.

[0282] The amount of ink droplets discharged is preferably 3.0 to 9.0 pL from the viewpoint of increasing the pattern forming speed and forming a finer pattern.

[0283] Examples of electronic components include printed wiring boards, semiconductor IC packages, and micro LEDs.

[0284] In the example of the base material of the metal portion of the electronic component, nickel, aluminum, etc. may be contained in addition to copper.

[0285] (2) Step of irradiating with active rays

[0286] In this step, the ink applied to the surface of the substrate is irradiated with active rays to cure the ink.

[0287] The active rays can be selected from, for example, electron beams, ultraviolet rays, α rays, γ rays, and X-rays, and are preferably ultraviolet rays or electron beams.

[0288] The ultraviolet light is preferably light having a peak wavelength of 360 to 410 nm. In addition, the ultraviolet light is preferably irradiated from an LED light source. LEDs radiate less heat than conventional light sources (such as metal halide lamps). Therefore, by using LEDs, the ink becomes difficult to dissolve when irradiated with active rays, and it becomes difficult to produce uneven gloss.

[0289] (3) Heating process

[0290] The inkjet recording method of the present invention may further include a step of heating the substrate at 140° C. or higher.

[0291] By performing this heating step, the hardness of the solder resist is improved.

[0292] The heating temperature of the substrate is preferably 140 to 180° C. The heating time is preferably 30 to 120 minutes, more preferably 30 to 60 minutes.

[0293] [Solder Resist]

[0294] The solder resist of the present invention is characterized by containing the above-mentioned curable composition for inkjet.

[0295] That is, the solder resist of the present invention is formed by irradiating the above-mentioned curable composition for inkjet with active rays. The above-mentioned solder resist can be formed by the above-mentioned inkjet recording method.

[0296] The resistance value of solder resist is 1.0×10 8 Ω or more. In addition, the above resistance value is preferably 1.0×10 8 ~1.0×10 18 Ω, more preferably 1.0×10 10 ~1.0×10 18 The above resistance value is particularly preferably 1.0×10 11 ~1.0×10 18 Ω.

[0297] [Printed wiring board]

[0298] The printed wiring board according to the present invention has the above-mentioned solder resist on a base material (substrate).

[0299] As the base material on which the solder resist is formed, a base substrate having a conductive film such as copper foil formed thereon can be used. The base substrate includes a rigid substrate and a flexible substrate.

[0300] Examples of the rigid substrate include phenolic paper substrates, paper epoxy substrates, glass epoxy substrates, glass polyimide substrates, Teflon (registered trademark) substrates, PPO substrates, composite base epoxy substrates, and the like.

[0301] Examples of the material of the flexible substrate include a PET film and a polyimide film.

[0302] Example

[0303] The present invention is specifically described below by way of examples, but the present invention is not limited to these examples. It should be noted that, in the following examples, the operation is performed at room temperature (25° C.) unless otherwise specified. In addition, “%” and “parts” mean “mass %” and “mass parts”, respectively, unless otherwise specified.

[0304] [Material preparation]

[0305] <Polymerizable compounds>

[0306] As the polymerizable compound, the following compounds were used.

[0307]

Chemistry 13

[0308]

[0309] ·Dipentaerythritol hexaacrylate (6 functional)

[0310] · Propoxylated (3) trimethylolpropane triacrylate (3 functional)

[0311] ·Dipropylene glycol diacrylate (2-functional)

[0312] <Nitrogen-containing aromatic heterocyclic compound having a tertiary amine>

[0313] As the nitrogen-containing aromatic heterocyclic compound having a tertiary amine, the following B-1 to B-10 were used.

[0314]

Chemistry 14

[0315]

[0316]

Chemistry 15

[0317]

[0318] <Other nitrogen-containing aromatic heterocyclic compounds>

[0319] As other nitrogen-containing aromatic heterocyclic compounds, the following compounds were used.

[0320]

Chemistry 16

[0321]

[0322] <Polymerization initiator>

[0323] As the polymerization initiator, the following initiators 1 to 3 were used.

[0324] Initiator 1: Omnirad 907 (manufactured by IGM Resins BV) (acetophenone-based initiator, intramolecular cleavage type, α-aminoalkyl phenyl ketone)

[0325] Initiator 2: Omnirad 819 (manufactured by IGM Resins BV) (acylphosphine-based initiator, intramolecular cleavage type, bis(2,4,6-trimethylbenzoyl)-phenyl-phosphine oxide phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide)

[0326] Initiator 3: Speedcure ITX (Saturdaymer Co., Ltd.) (thioxanthone-based initiator, hydrogen abstraction type, 2-isopropylthioxanthone)

[0327] <Polymerization inhibitor>

[0328] As the polymerization inhibitor, the following polymerization inhibitors were used.

[0329] ·MEHQ (monomethyl hydroquinone ether)

[0330] ·Irgastab UV-10 (manufactured by BASF Japan, N-oxyl type)

[0331] NPHA (N-nitroso-N-phenylhydroxylamine aluminum, nitrosoamines)

[0332] <Preparation of Pigment Dispersion>

[0333] (Preparation of yellow pigment dispersion)

[0334] The following materials were placed in a stainless steel beaker, heated and stirred on a hot plate at 65°C for 1 hour to dissolve, and cooled to room temperature. Then, 15.0 parts by mass of yellow pigment PY185 (パリオトールイエローD1155, BASF company) were added to the stainless steel beaker. Then, the mixed solution in the stainless steel beaker and 200g of zirconium oxide beads (diameter 0.5mm) were placed in a glass bottle and sealed. It was dispersed with a paint shaker (5400, Red Devil company) until it became the desired particle size, and then the zirconium oxide beads were removed to prepare a yellow pigment dispersion.

[0335] Pigment dispersant 1 (EFKA PX4701, manufactured by BASF) 11.2 parts by mass

[0336] Synergist 1 (Solsperse 22000, manufactured by Lubrizol) 3.0 parts by mass

[0337] Dispersion medium: 70.8 parts by mass of dipropylene glycol diacrylate

[0338] (Preparation of cyan pigment dispersion)

[0339] A cyan pigment dispersion was prepared in the same manner as the yellow pigment dispersion except that the amount of the dispersant and the amount of the dispersion medium used were changed as follows, the pigment added was changed to 23.0 parts by mass of cyan pigment PB15:4 (Clomofine Bru 6332JC, manufactured by Dainichi Seika Industries, Ltd.), and no synergist 1 was added. It should be noted that cyan pigment PB15:4 is a pigment treated with a synergist.

[0340] Pigment dispersant 1 (EFKA PX4701, manufactured by BASF) 7.0 parts by mass

[0341] Dispersion medium: 70.0 parts by mass of dipropylene glycol diacrylate The yellow pigment and the cyan pigment are subjected to a water washing treatment to reduce the amount of impurities (conductive substances and ionic impurities).

[0342] <Dye>

[0343] As dyes, the following dyes were used.

[0344] Solvent Blue 35

[0345] [Preparation of inkjet ink]

[0346] <Preparation of inkjet ink 1>

[0347] 3.0 parts by mass of the yellow pigment dispersion and 3.0 parts by mass of the cyan pigment dispersion were mixed, and the following materials were added while stirring the obtained mixed solution to prepare an inkjet ink.

[0348] (Polymerizable compound)

[0349]

[0350]

[0351] The obtained ink composition was filtered using a 3.0 μm membrane filter (manufactured by ADVANTECH), thereby obtaining inkjet ink 1.

[0352] <Preparation of inkjet inks 2 to 24>

[0353] In the preparation of the inkjet ink 1, inkjet inks 2 to 24 were obtained in the same manner except that the materials and amounts used were changed so as to have the compositions of the inks shown in the following Tables I to III.

[0354]

Table 1

[0355] Table I Unit: [Parts by mass]

[0356]

[0357]

Table 2

[0358] Table II Unit: [Parts by mass]

[0359]

[0360]

Table 3

[0361] Table III Unit: [parts by mass]

[0362]

[0363] [Formation of Cured Film]

[0364] Each prepared ink is filled in an inkjet recording device having an inkjet recording head with a piezoelectric inkjet nozzle. Next, a voltage is applied to the inkjet recording head so that the droplet discharge amount becomes 6.0 pL. Then, a solid pattern of 20 mm × 50 mm and 30 μm thick and a comb-shaped fine line pattern with a line and space of 100 μm and a thickness of 30 μm are formed on a copper-clad laminate for a printed wiring board (FR-4 thickness 1.6 mm, size 150 mm × 95 mm). When the pattern is formed, the ink in the inkjet recording head is heated with a built-in heater of the recording head so that the ink becomes 80°C.

[0365] The typed pattern was illuminated using an LED lamp (Fire Jet(TM) FJ100, manufactured by Phoseon Technology, wavelength 395 nm) at an intensity of 500 mJ / cm 2 The ink layer is cured by irradiating ultraviolet light.

[0366] Then, the patterned copper-clad laminate was placed in an oven set at 150° C. and heated for 60 minutes to further cure the ink layer, thereby obtaining a cured film.

[0367] The cured films were formed under three conditions: immediately after the ink was prepared, after the ink was stored at 85° C. for 4 days, and after the ink was stored at 85° C. for 8 days.

[0368] [evaluate]

[0369] <Color change>

[0370] In the above-mentioned [Formation of Cured Film], the solid pattern cured film before being placed in the oven was measured by reflected light measurement under the following conditions using a fluorescence spectrophotometer FD-7 (manufactured by Konica Minolta Inc.). ＊ a ＊ b ＊ .

[0371] Lighting conditions: M0 (A), observation light source: D50, observation conditions: 2° field of view. The cured film was heated in an oven at 150° C. for 60 minutes, and the L ＊ a ＊ b ＊ .

[0372] The cured film heated in an oven at 150°C for 60 minutes was immersed in a 260°C solder bath for 10 seconds three times, and the L ＊ a ＊ b ＊ .

[0373] ΔE before and after 150° C. for 60 minutes and before and after soldering was calculated using the following formula and evaluated based on the following criteria, with “A”, “B” and “C” being considered as having no practical problems.

[0374] The L was measured for the cured films formed under three conditions: immediately after the ink was prepared, after the ink was stored at 85° C. for 4 days, and after the ink was stored at 85° C. for 8 days. ＊ a ＊ b ＊ .

[0375] ΔE=[(ΔL ＊ ) 2 +(Δa ＊ ) 2 +(Δb ＊ ) 2 ] 1 / 2

[0376] (Benchmark)

[0377] A: ΔE≤6

[0378] B: 6<ΔE≤10

[0379] C: 10<ΔE≤15

[0380] D: 15<ΔE

[0381] <Adhesion>

[0382] In the obtained solid pattern cured film, a checkerboard-shaped cut is formed according to the cross-cut method of JIS K5600-5-6:1999, and an adhesive tape is attached. The adhesive tape is peeled off, and the peeling state of the cured film from the substrate is observed to determine the adhesion residual rate. The adhesion residual rate refers to the ratio of the number of grids remaining in the cured film after the adhesive tape is peeled off relative to the number of grids produced by forming the above-mentioned cuts.

[0383] The above-mentioned adhesion residual rate was calculated for the cured films formed under three conditions: immediately after the ink was prepared, after the ink was stored at 85°C for 4 days, and after the ink was stored at 85°C for 8 days. Based on each adhesion residual rate, the adhesion was evaluated according to the following evaluation criteria. "A", "B", and "C" were considered to be practically problem-free.

[0384] (Benchmark)

[0385] A: The adhesion residual rate is 100%

[0386] B: The adhesion residual rate is 80% or more and less than 100%

[0387] C: The adhesion residual rate is 60% or more and less than 80%

[0388] D: The adhesion residual rate is less than 60%

[0389] <Pencil hardness>

[0390] The surface pencil hardness of each sample of the produced cured film was measured according to the method described in "JIS Standard K-5400" using Hi-Uni (registered trademark) manufactured by Mitsubishi Pencil.

[0391] Specifically, the wooden part of the pencil was cut to a core length of 5 to 6 mm. The top of the core was smoothed with abrasive paper to obtain a pencil with a circular cross section. The pencil was held at an angle of 45 degrees relative to the sample surface, and a load of 1 kg was applied to the sample surface, and the cured film was scratched at an angle of 45 degrees.

[0392] The pencil hardness of the cured film formed under three conditions: immediately after the ink was prepared, after the ink was stored at 85°C for 4 days, and after the ink was stored at 85°C for 8 days, was measured, and the maximum pencil hardness at which the cured film did not reach the recording medium was evaluated. The maximum pencil hardness of 4H or more was considered to be within the range of no problem in practical use.

[0393] <Solder Heat Resistance>

[0394] As a method for evaluating the heat resistance of the cured film, the following solder heat resistance was evaluated.

[0395] The solid pattern typed sample was immersed in a 260°C solder bath for 10 seconds three times, and the adhesion residual rate was calculated by the same method as the above "Adhesion", and the peeling state of the cured film was evaluated using the following criteria. The adhesion residual rate was calculated for the cured film formed under three conditions: immediately after the ink was prepared, after the ink was stored at 85°C for 4 days, and after the ink was stored at 85°C for 8 days, and the "A" and "B" in the following criteria were set to the range without practical problems.

[0396] (Benchmark)

[0397] A: The adhesion residual rate is more than 90% to 100%

[0398] B: The adhesion residual rate is 90% or more and less than 100%

[0399] C: The adhesion residual rate is 70% or more and less than 90%

[0400] D: The adhesion residual rate is less than 70%

[0401] <Plating resistance>

[0402] For each sample of the cured film obtained above, plating was performed under the conditions of 0.5 μm nickel and 0.03 μm gold using a commercially available chemical nickel plating bath and a chemical gold plating bath, and a cross-cut stripping test was performed. For the cured film formed under three conditions: immediately after the ink was prepared, after the ink was stored at 85°C for 4 days, and after the ink was stored at 85°C for 8 days, the number of remaining checkerboards was counted out of 100, and the evaluation was performed based on the following criteria. In the following criteria, "A" and "B" are set to the range without practical problems.

[0403] (Benchmark)

[0404] A: The remaining number is 100 out of 100.

[0405] B: The number of surviving cells is 80 to 99 out of 100.

[0406] C: The number of surviving cells is 60 to 79 out of 100.

[0407] D: The number of surviving cells is less than 59 out of 100.

[0408] <Viscosity fluctuation>

[0409] For each prepared ink, the viscosity of each ink at 80°C was measured using Physica MCR301 (manufactured by Anton Paar) at a shear rate of 1000 (1 / s). The measurements were performed immediately after the ink was prepared, after being stored at 85°C for 4 days, and after being stored at 85°C for 8 days. The difference between the viscosity of the ink immediately after preparation and the viscosity after being stored at 85°C for 4 days (viscosity fluctuation) and the difference between the viscosity of the ink immediately after preparation and the viscosity after being stored at 85°C for 8 days (viscosity fluctuation) were calculated and evaluated using the following criteria. In the following criteria, "A", "B" and "C" are set to ranges that are not problematic in practical use.

[0410] (Benchmark)

[0411] A: Viscosity change is less than 0.3 mPa·s

[0412] B: Viscosity fluctuation is 0.3 mPa·s or more and less than 0.7 mPa·s

[0413] C: Viscosity fluctuation is 0.7 mPa·s or more and less than 1.0 mPa·s

[0414] D: Viscosity fluctuation is 1.0 mPa·s or more

[0415] <Average particle size variation>

[0416] For each prepared ink, the average particle size (Z-average) of each ink was measured by dynamic light scattering using DataScan ZSP (manufactured by Malvern). The ink was diluted 200 times and measured. The measurement was carried out at a temperature of 25°C. The measurement was carried out immediately after the ink was adjusted, after being stored at 85°C for 4 days, and after being stored at 85°C for 8 days. The difference between the average particle size of the ink immediately after the adjustment and the average particle size after being stored at 85°C for 4 days (average particle size change) and the difference between the average particle size of the ink immediately after the adjustment and the average particle size after being stored at 85°C for 8 days (average particle size change) were calculated and evaluated using the following criteria. In the following criteria, "A" and "B" are set to ranges that are not problematic in practical use.

[0417] (Benchmark)

[0418] A: The average particle size varies less than 15 nm

[0419] B: The average particle size varies from 15 nm to less than 30 nm

[0420] C: The average particle size varies from 30 nm to less than 50 nm

[0421] D: Average particle size variation is 50 nm or more

[0422]

Table 4

[0423] Table IV

[0424]

[0425]

Table 5

[0426] Table V

[0427]

[0428]

Table 6

[0429] Table VI

[0430]

[0431] As shown in the above results, the ink of the present invention can suppress the change in viscosity, particle size and anti-discoloration performance over time at high temperature compared with the ink of the comparative example. In addition, as for the cured film formed using the ink of the present invention, it was confirmed that: compared with the cured film formed using the ink of the comparative example, the adhesion, hardness, solder heat resistance and plating resistance over time at high temperature are good.

Claims

1. A curable composition for inkjet for a metal-containing substrate, comprising a polymerizable compound, a polymerization initiator and a pigment, and curing by irradiation with active rays, characterized in that: Contains: Nitrogen-containing aromatic heterocyclic compounds with tertiary amines.

2. The curable composition for inkjet according to claim 1, characterized in that As the nitrogen-containing aromatic heterocyclic compound, a benzene ring is not directly condensed to an aromatic heterocyclic ring.

3. The curable composition for inkjet for a metal-containing substrate according to claim 1, wherein The polymerizable compound is a polymerizable compound having a carboxyl group, a hydroxyl group or an epoxy group.

4. The curable composition for inkjet for a metal-containing substrate according to claim 1, wherein The nitrogen-containing aromatic heterocyclic compound includes a five-membered nitrogen-containing aromatic heterocyclic compound.

5. The curable composition for inkjet for a metal-containing substrate according to claim 1, wherein The nitrogen-containing aromatic heterocyclic compound includes a triazole compound.

6. The curable composition for inkjet for a metal-containing substrate according to claim 5, wherein: The triazole compound has a structure represented by the following general formula (a): In the general formula (a), Ra and Rb each represent an alkyl group having 1 to 20 carbon atoms.

7. The curable composition for inkjet for a metal-containing substrate according to claim 3, wherein: The polymerizable compound having a carboxyl group has a structure represented by the following general formula (1): General formula (1) In the general formula (1), X represents a substituent having at least one selected from acryloyl, methacryloyl, allyl, vinyl and derivatives thereof 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.

8. The curable composition for inkjet for a metal-containing substrate according to claim 3, wherein: The polymerizable compound having a hydroxyl group is epoxy acrylate obtained by reacting (meth)acrylic acid with an epoxy compound.

9. The curable composition for inkjet for a metal-containing substrate according to claim 3, wherein: The polymerizable compound having a carboxyl group, a hydroxyl group, or an epoxy group has any one of a bisphenol structure, a cresol novolac structure, or a phenol novolac structure.

10. The curable composition for inkjet for a metal-containing substrate according to claim 1, wherein As the polymerization initiator, thioxanthone is contained.

11. The curable composition for inkjet for a metal-containing substrate according to claim 1, wherein As the polymerization inhibitor, N-oxyls or nitrosoamines are contained.

12. A solder resist, characterized in that: A curable composition for inkjet for a substrate containing a metal according to any one of claims 1 to 11.

13. An inkjet recording method, wherein a curable composition for inkjet is discharged onto a substrate and cured by active radiation, wherein: As the curable composition for inkjet, the curable composition for inkjet for a metal-containing substrate according to any one of claims 1 to 11 is used, As the substrate, a substrate containing a metal is used.

14. The inkjet recording method according to claim 13, wherein: The method comprises: heating the substrate at a temperature above 140° C.

15. The inkjet recording method according to claim 13, wherein The method comprises the step of heating the curable composition for inkjet for the metal-containing substrate to 40° C. or higher in an inkjet head.

Images