Curable composition for inkjet printing, solder resist, and inkjet recording method

Abstract

Provided is a curable composition for inkjet printing which gives coating films capable of preventing themselves and the underlying substrates from discoloring during thermal curing and through soldering and which can be inhibited from changing in viscosity, particle diameter, or discoloration-preventing performance at high temperatures with the lapse of time.　The curable composition for inkjet printing includes (A) a polymerizable compound and (B) a polymerization initiator and cures upon irradiation with actinic rays, the curable composition being characterized by containing (C) a triazine compound and (D) a triazole compound wherein the triazole compound (D) having no benzene ring fused to the triazole ring.

Description

Curable composition for inkjet printing, solder resist, and inkjet recording method

[0001] The present invention relates to an inkjet curable composition, a solder resist, and an inkjet recording method, and more particularly to an inkjet curable composition, a solder resist, and an inkjet recording method that can prevent discoloration of a coating film or a substrate under the coating film during thermal curing and before and after soldering, and that can suppress changes in viscosity, particle size, and discoloration prevention performance over time at high temperatures.

[0002] Conventionally, a technique has been known in which an alkali-developable photoresist contains a nitrogen-containing aromatic heterocyclic compound such as melamine, benzotriazole, or triazole (see, for example, Patent Document 1). This technique can promote adhesion of the photoresist to a substrate (e.g., copper) and suppress discoloration of the substrate.

[0003] On the other hand, it is known that an insulating film (solder resist) is formed by applying and curing ink to a printed wiring board in a printed circuit board for the purpose of protecting a circuit pattern, using an inkjet method. Specifically, a method for forming solder resist is known in which a solder resist inkjet ink (hereinafter also simply referred to as "ink") is applied, cured with actinic radiation, and then cured with heat. A technique for adding a nitrogen-containing aromatic heterocyclic compound to such solder resist ink has also been proposed (see, for example, Patent Document 2). For example, Patent Document 2 discloses a technique for promoting adhesion to copper by adding a nitrogen-containing aromatic heterocyclic compound to a solder resist ink.

[0004] International Publication No. 2014 / 167671 Patent No. 5986701

[0005] However, the solder resist ink described in Patent Document 2 has a problem in that it does not sufficiently suppress discoloration of the coating film or the substrate under the coating film during the curing process or soldering process. In particular, in recent years, from the perspective of environmental friendliness, there has been a shift from the eutectic solder that has traditionally been used in the soldering process to lead-free solder with a higher melting point, and there is a demand for suppression of discoloration under higher temperature conditions.

[0006] Furthermore, inkjet inks are required to have storage stability of about one month to two years at temperatures around room temperature, for example, about 0 to 40°C. In addition, in order to ensure jetting suitability, they are often used after being heated to about 40 to 100°C to reduce viscosity. Therefore, it is desirable that the ink viscosity and particle size, as well as the coating properties and discoloration prevention performance required for a solder resist, including adhesion and hardness, do not change over time at room temperature or at high temperatures. However, achieving such performance has been even more difficult.

[0007] The present invention has been made in consideration of the above problems and circumstances. An object of the present invention is to provide an inkjet curable composition that can suppress changes in viscosity and particle size over time at high temperatures, and changes in the ability to prevent discoloration of the coating film and the substrate underneath the coating film, and that is compatible with lead-free soldering processes. Another object of the present invention is to improve the coating film adhesion, hardness, heat resistance, and plating resistance over time at high temperatures in a solder resist and inkjet recording method that use the above inkjet curable composition.

[0008] The present inventors have investigated the causes of the above problems in order to solve them. They have found that the above problems can be solved by adding a triazine compound and a triazole compound whose benzene ring is not directly condensed to a curable composition for inkjet printing, which contains a polymerizable compound and a polymerization initiator. Specifically, they have found that adding the two components, the triazine compound and the triazole compound, to the curable composition for inkjet printing can suppress changes in viscosity, particle size, and discoloration prevention performance of the coating film and the substrate beneath the coating film over time at high temperatures. They have also found that a solder resist using such a curable composition for inkjet printing can achieve improved adhesion, hardness, heat resistance, and plating resistance even over time at high temperatures. Specifically, the above problems of the present invention can be solved by the following means.

[0009] 1. A curable composition for inkjet that contains (A) a polymerizable compound and (B) a polymerization initiator and is cured by exposure to actinic rays, the curable composition for inkjet being characterized in that it contains (C) a triazine compound and (D) a triazole compound, and a benzene ring is not condensed to the triazole ring of the triazole compound (D).

[0010] 2. The curable composition for inkjet according to item 1, wherein the ratio of the content of the triazole compound (D) to the content of the triazine compound (C) ((D) triazole compound / (C) triazine compound) is 0.2 to 2.0.

[0011] 3. The curable composition for inkjet recording described in item 1, wherein the triazine compound (C) is a compound represented by the following general formula (1):

[0012]

[0013] However, in the general formula (1), R １ , R ２ , and R ３ are each independently a hydrogen atom, an amino group, or a group represented by the formula (2): -NHR ４ an organic group represented by formula (3): —NR ６ R ７ an organic group represented by the formula (I), an organic group other than the above-mentioned substituents, or a halogen atom; １ , R ２ , and R ３ At least two of the above are an amino group, an organic group represented by the formula (2), or an organic group represented by the formula (3). ４、 R ６、 R ７ is -CH ２ OR ５ , or -COOR ５ is a group represented by R ５ is a hydrogen atom or an alkyl group.

[0014] 4. R in the general formula (1) １ , R ２ , and R ３4. The curable composition for inkjet recording according to item 3, wherein is not an amino group.

[0015] 5. R in the general formula (1) １ , R ２ , and R ３ are each independently an organic group represented by formula (2).

[0016] 6. The curable composition for inkjet recording described in item 1, wherein the triazole compound (D) does not have a primary amine structure.

[0017] 7. The curable composition for inkjet according to item 6, wherein the triazole compound (D) has a tertiary amine structure.

[0018] 8. The curable composition for inkjet according to item 1, wherein the curable composition for inkjet is used as an insulating film in a soldering process using lead-free solder.

[0019] 9. The curable composition for inkjet recording according to item 1, further comprising a wax.

[0020] 10. The curable composition for inkjet according to item 9, wherein the wax comprises at least one wax selected from the group consisting of ester waxes and ketone waxes.

[0021] 11. The curable composition for inkjet recording described in item 9, wherein the wax is a wax having an organic group having 12 to 60 carbon atoms.

[0022] 12. The curable composition for inkjet recording according to item 1, further comprising a pigment and a pigment dispersant.

[0023] 13. The curable composition for inkjet according to item 12, wherein the pigment dispersant is a block copolymer having an amine value of 5 to 100 mgKOH / g.

[0024] 14. The curable composition for inkjet recording according to item 1, further comprising a thermal polymerization inhibitor.

[0025] 15. The curable composition for inkjet described in item 1, wherein the polymerizable compound (A) is a polymerizable compound having any one of a carboxy group, a hydroxy group, and an epoxy group.

[0026] 16. The curable composition for inkjet recording according to item 1, which has a viscosity of 5 to 50 mPa·s at a discharge temperature.

[0027] 17. A solder resist comprising the curable composition for inkjet according to any one of items 1 to 16.

[0028] 18. An inkjet recording method comprising ejecting a curable composition for inkjet onto a substrate and curing the composition with actinic radiation, the method comprising: using the curable composition for inkjet according to any one of items 1 to 16 as the curable composition for inkjet; and using a substrate containing a metal as the substrate.

[0029] The above-described means of the present invention can provide an inkjet curable composition that can suppress changes in viscosity and particle size over time at high temperatures, and changes in the ability to prevent discoloration of the coating film and the substrate underneath the coating film, and that is compatible with lead-free soldering processes. Furthermore, this inkjet curable composition also has excellent storage stability in temperature environments of approximately 60 to 100°C (hereinafter also referred to as "high-temperature storage stability"). That is, the inkjet curable composition exhibits the effect of being less susceptible to deterioration of the various performances described above when stored in an environment within the above-described temperature range. Furthermore, the above-described means of the present invention can improve the coating film adhesion, hardness, heat resistance, and plating resistance over time in a solder resist and inkjet recording method that use the inkjet curable composition.

[0030] The mechanism by which the effects of the present invention are manifested or the mechanism of action is not clear, but is speculated as follows.

[0031] The curable composition for inkjet of the present invention is a curable composition for inkjet that contains (A) a polymerizable compound and (B) a polymerization initiator, and is cured by exposure to actinic rays. The curable composition for inkjet also contains (C) a triazine compound and (D) a triazole compound.

[0032] The (D) triazole compound is one in which a benzene ring is not fused to the triazole ring. Such a (D) triazole compound, for example, forms a coordinate bond with copper during thermal curing (e.g., a temperature range of about 120 to 200°C) and exhibits excellent anti-tarnish performance, such as rust prevention. However, during soldering (e.g., a temperature range of about 250 to 300°C), the coordinate bond between the (D) triazole compound and copper is broken, resulting in insufficient coordination. For this reason, the anti-tarnish performance during soldering is limited when the (D) triazole compound is used alone. Note that a triazole compound in which a benzene ring is fused to the triazole ring has weak coordination with copper and does not exhibit sufficient anti-tarnish performance.

[0033] On the other hand, when the triazine compound (C) is thermally cured within the temperature range described above, the coordination bond with copper is insufficient, and the discoloration prevention performance may not be fully exhibited. However, during soldering, the coordination bond with copper is promoted, and therefore the discoloration prevention performance during soldering is high.

[0034] The curable composition for inkjet of the present invention uses a (D) triazole compound that exhibits excellent anti-discoloration performance during thermal curing in combination with a (C) triazine compound that exhibits excellent anti-discoloration performance during soldering. Therefore, it is presumed that the curable composition for inkjet of the present invention can exhibit excellent anti-discoloration performance over a wide temperature range, from when thermally cured at about 120 to 200°C to when soldered at about 250 to 300°C. In other words, it is presumed that the combined use of the (D) triazole compound and the (C) triazine compound in the curable composition for inkjet of the present invention improves anti-discoloration performance over time at high temperatures.

[0035] Furthermore, it was found that by using a (D) triazole compound and a (C) triazine compound in combination, increases in ink viscosity and particle size can be prevented even when the ink is stored at about 40°C for about one month and then at 85°C for about four days. The effect of suppressing increases in ink viscosity and particle size as described above was insufficient when either the (D) triazole compound or the (C) triazine compound was used alone. Although the detailed mechanism is unknown, it is speculated that the interaction between the (D) triazole compound and the (C) triazine compound and the pigment suppresses pigment aggregation over a wide range of temperatures, thereby preventing increases in ink viscosity and particle size.

[0036] The curable composition for inkjet of the present invention contains (A) a polymerizable compound and (B) a polymerization initiator, and is cured by irradiation with actinic rays. The curable composition for inkjet contains (C) a triazine compound and (D) a triazole compound, and is characterized in that a benzene ring is not fused to the triazole ring of the triazole compound (D). This feature is a technical feature common to or corresponding to each of the following embodiments.

[0037] As an embodiment of the present invention, it is preferable that the ratio of the content of the (D) triazole compound to the content of the (C) triazine compound ((D) triazole compound / (C) triazine compound) is 0.2 to 2.0, in terms of improving the discoloration prevention performance over time at high temperatures.

[0038] The triazine compound (C) is preferably a compound represented by the following general formula (1), in that the ability to prevent discoloration over time at high temperatures is improved.

[0039]

[0040] However, in the above general formula (1), R １ , R ２ , and R ３ are each independently a hydrogen atom, an amino group, or a group represented by the formula (2): -NHR ４ an organic group represented by formula (3): —NR ６ R ７ an organic group represented by the formula (I), an organic group other than the above-mentioned substituents, or a halogen atom;１ , R ２ , and R ３ At least two of the above are an amino group, an organic group represented by the above formula (2), or an organic group represented by the above formula (3). ４、 R ６、 R ７ is -CH ２ OR ５ , or -COOR ５ is a group represented by R ５ is a hydrogen atom or an alkyl group.

[0041] When the triazine compound (C) is a compound represented by the general formula (1), from the viewpoint of high-temperature storage stability of the curable composition for inkjet, R １ , R ２ , and R ３ is an amino group (-NH ２ Furthermore, from the viewpoint of the high-temperature storage stability, it is preferable that R １ , R ２ , and R ３ are each independently an organic group represented by the above formula (2).

[0042] From the viewpoint of the high-temperature storage stability, it is preferable that the triazole compound (D) does not have a primary amine structure. Furthermore, from the viewpoint of the high-temperature storage stability, it is more preferable that the triazole compound (D) has a tertiary amine structure.

[0043] As described above, the curable composition for inkjet printing has excellent anti-discoloration properties over time at high temperatures, and is suitable for use as an insulating film in a soldering process using lead-free solder.

[0044] The curable composition for inkjet preferably further contains a wax from the viewpoint of further suppressing discoloration of the coating film and the substrate beneath the coating film during the curing process and the soldering process. In particular, it is more preferable that the wax contains at least one wax selected from the group consisting of ester waxes and ketone waxes. In another preferred embodiment, the wax is a wax having an organic group having 12 to 60 carbon atoms.

[0045] The curable composition for inkjet may further contain a pigment as a colorant and a pigment dispersant. When the curable composition for inkjet further contains a pigment and a pigment dispersant, the pigment dispersant is preferably a block copolymer having an amine value of 5 to 100 mgKOH / g, from the viewpoint of dispersion stability of the pigment.

[0046] The polymerizable compound (A) is preferably a polymerizable compound having a carboxy group, a hydroxy group, or an epoxy group, from the viewpoint of improving the heat resistance of a cured film such as a solder resist.

[0047] From the viewpoint of further improving the ejection properties from an inkjet head, the inkjet curable composition preferably has a viscosity of 5 to 50 mPa·s at the ejection temperature.

[0048] The curable composition for inkjet of the present invention is suitably used for a solder resist.

[0049] The inkjet recording method of the present invention is an inkjet recording method in which an inkjet curable composition is ejected onto a substrate and cured by actinic radiation. The inkjet recording method of the present invention is characterized in that the inkjet curable composition of the present invention is used as the inkjet curable composition and a metal-containing substrate is used as the substrate. This makes it possible to improve the physical properties of a solder resist made of the inkjet curable composition.

[0050] The present invention, its constituent elements, and embodiments and modes for carrying out the present invention will be described below. In this application, the symbol "to" is used to mean that the numerical values ​​before and after it are included as the lower and upper limits. In addition, in this specification, "(meth)acrylate" means acrylate or methacrylate, and "(meth)acrylic" means acrylic or methacrylic.

[0051] [Curable composition for inkjet] First, an embodiment of the curable composition for inkjet of the present invention will be described. The curable composition for inkjet of this embodiment contains (A) a polymerizable compound and (B) a polymerization initiator, and is cured by irradiation with actinic rays. The curable composition for inkjet of this embodiment contains (C) a triazine compound and (D) a triazole compound, and is characterized in that the triazole ring of (D) the triazole compound is not fused with a benzene ring.

[0052] Hereinafter, the curable composition for inkjet of this embodiment will also be simply referred to as a "curable composition for inkjet," "curable composition," or "ink." Furthermore, the polymerizable compound (A) will sometimes be referred to as the component (A). Similarly, the polymerization initiator (B) will sometimes be referred to as the component (B), the triazine compound (C) will sometimes be referred to as the component (C), and the triazole compound (D) will sometimes be referred to as the component (D).

[0053] <Component (A): Polymerizable Compound> The component (A) is a polymerizable compound. The polymerizable compound as the component (A) is a compound that polymerizes and crosslinks when irradiated with actinic rays. The polymerizable compound may be a compound that further polymerizes and crosslinks when heated after being irradiated with actinic rays.

[0054] Examples of actinic 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.

[0055] The polymerizable compound as component (A) 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 a radically polymerizable ethylenically unsaturated bond.

[0056] The polymerizable compound as component (A) is preferably a polymerizable compound having a carboxy group, a hydroxy group, or an epoxy group, as this improves the adhesion between the solder resist and the substrate and further enhances the effect of inhibiting discoloration before and after soldering. The reason why such an effect is exhibited is not clear, but it is presumed that this is because the carboxy group, hydroxy group, or epoxy group also interacts with the substrate, resulting in a more dense coating of the substrate.

[0057] (Polymerizable Compound Having a Carboxy Group) The polymerizable compound having a carboxy group is preferably a radically polymerizable compound. The radically polymerizable compound may be contained in the ink alone or in a combination of two or more types.

[0058] Examples of the actinic radiation-polymerizable compound having a carboxy group as the radical polymerizable compound include (meth)acrylic acid, carboxyethyl (meth)acrylate, 2-acryloyloxyethyl phthalic acid, 2-acryloyloxyethyl hexahydrophthalic acid, etc. Of these, the radical polymerizable compound is preferably (meth)acrylic acid or carboxyethyl acrylate (also referred to as "carboxy group-containing polymerizable compound A-10" described in the examples).

[0059] The polymerizable compound having a carboxy group may be monofunctional or polyfunctional, but from the viewpoint of preventing a decrease in adhesion due to cure shrinkage of the solder resist, the polymerizable compound having a carboxy group is preferably a compound having five or fewer functionalities.

[0060] Furthermore, it is preferable that the polymerizable compound having a carboxy group has a structure represented by the following general formula (4), in that this improves the adhesion between the solder resist and the substrate.

[0061]

[0062] In the general formula (4), X represents a substituent having at least one group selected from an acryloyl group, a methacryloyl group, an allyl group, a vinyl group, and derivatives thereof at its terminal. Q represents an oxygen atom or NR ９ represents R ９ represents a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group. ８ represents an unsubstituted alkylene group having 1 to 6 carbon atoms.

[0063] The compound having the structure represented by general formula (4) has two carbonyl groups (C(=O)) in the molecule via unsubstituted alkylene groups, whereby the two oxygen atoms contained in the two carbonyl groups form coordinate bonds with the metal atom, thereby more sufficiently enhancing the effect of inhibiting discoloration before and after soldering.

[0064] From the viewpoint of making the coordinate bond between the two oxygen atoms and the metal atom more stable and more sufficiently increasing the adhesion to the substrate, R ８ is preferably an unsubstituted alkylene group having 1 to 4 carbon atoms. From the viewpoint of further enhancing the effect of suppressing discoloration before and after soldering, R ８ is more preferably an unsubstituted alkylene group having 1 or 2 carbon atoms. Thus, when the coordinate bond is formed, the metal atom, the two oxygen atoms, and R ８ (alkylene group), a ring structure is formed, and the coordinate bond is more stable. From the same viewpoint, Q is preferably an oxygen atom.

[0065] Furthermore, the polymerizable group at the terminal of X is preferably a (meth)acryloyl group. Because the (meth)acryloyl group is highly reactive, it is easily polymerized and incorporated into the coating film. Therefore, a compound having a (meth)acryloyl group as a polymerizable group can fully exhibit the effect of improving adhesion due to the carboxyl group.

[0066] Examples of compounds having the structure represented by the above general formula (4) include the compounds shown below, but the present invention is not limited to these.

[0067]

[0068]

[0069] The polymerizable compound having a carboxy group may be a monomer or an oligomer, but is preferably a monomer. In this specification, the term "monomer" refers to a polymerizable compound that is a monomer having a molecular weight of less than 700. The molecular weight can be measured by gel permeation chromatography.

[0070] (Polymerizable Compound Having a Hydroxy Group) The polymerizable compound having a hydroxy group is not particularly limited as long as it is a compound having a hydroxy group in its structure. Specific examples of the polymerizable compound having a hydroxy group include hydroxyalkyl(meth)acrylate and hydroxy(meth)acrylate having an alicyclic structure.

[0071] Examples of hydroxyalkyl (meth)acrylates include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, etc. The above-mentioned 4-hydroxybutyl (meth)acrylate is a compound shown as the hydroxy group-containing polymerizable compound A-11 below.

[0072] Examples of hydroxy(meth)acrylates having an alicyclic structure include 1,4-cyclohexanedimethanol mono(meth)acrylate.

[0073] Furthermore, the polymerizable compound having a hydroxy group can also be an epoxy acrylate obtained by reacting (meth)acrylic acid with an epoxy compound. Commercially available epoxy acrylates can be used. Examples of such commercially available products include Epoxy Ester 70PA (manufactured by Kyoeisha Chemical Co., Ltd.), Epoxy Ester 200PA (manufactured by Kyoeisha Chemical Co., Ltd.), Epoxy Ester M-600A (manufactured by Kyoeisha Chemical Co., Ltd.), and DENACOL ACRYLATE DA-111 (manufactured by Nagase Chemtex Co., Ltd.). Of these, epoxy acrylates are preferred. Epoxy acrylates are preferred because they provide a better effect of inhibiting discoloration before and after soldering. The aforementioned Epoxy Ester 70PA (manufactured by Kyoeisha Chemical Co., Ltd.) is the compound shown below as hydroxy group-containing polymerizable compound A-12.

[0074]

[0075] (Polymerizable Compound Having Epoxy Group) The polymerizable compound having an epoxy group is not particularly limited as long as it is a compound having an epoxy group in its structure. Specific examples of the polymerizable compound having an epoxy group include an aliphatic alcohol-based epoxy, an aliphatic polyhydric alcohol-based epoxy, and a phenol-based epoxy.

[0076] Other examples of epoxy (meth)acrylates include the following:

[0077]

[0078] The polymerizable compounds having a carboxy group, a hydroxy group, or an epoxy group described above preferably have a bisphenol structure, a cresol novolac structure, or a phenol novolac structure in order to improve the effect of inhibiting discoloration before and after soldering. Examples of the bisphenol structure include a bisphenol A structure and a bisphenol F structure.

[0079] Examples of the polymerizable compound having any one of a bisphenol structure, a cresol novolac structure, and a phenol novolac structure include the above-mentioned epoxy group-containing polymerizable compound A-22, as well as the following compounds.

[0080]

[0081] The content of the polymerizable compound as component (A) is preferably in the range of 20 to 99% by mass, and more preferably in the range of 30 to 95% by mass, relative to the total mass of the curable composition for inkjet. By setting the content of the polymerizable compound as component (A) within the above numerical range, it is possible to improve the coating adhesion and hardness in the solder resist and inkjet recording method.

[0082] <Component (B): Polymerization Initiator> The component (B) is a polymerization initiator. The polymerization initiator as the component (B) is a compound that initiates polymerization and crosslinking of the polymerizable compound, which is the component (A), upon irradiation with actinic rays.

[0083] The polymerization initiator may be a radical polymerization initiator when the ink contains a radically polymerizable compound, or a cationic polymerization initiator when the ink contains a cationic polymerizable compound. Examples of radical polymerization initiators include intramolecular bond cleavage type radical polymerization initiators and hydrogen abstraction type radical polymerization initiators.

[0084] Examples of the intramolecular bond cleavage type radical polymerization initiator include acetophenone-based initiators such as diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, benzyl dimethyl ketal, 1-(4-isopropylphenyl)-2-hydroxy-2-methylpropan-1-one, 4-(2-hydroxyethoxy)phenyl-(2-hydroxy-2-propyl)ketone, 1-hydroxycyclohexyl-phenyl ketone, 2-methyl-2-morpholino(4-methylthiophenyl)propan-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 methylphenyl glyoxyesters.

[0085] Examples of commercially available acetophenone initiators include Omnirad 907 (manufactured by IGM) (molecular weight: 279) and Omnirad 379 (manufactured by IGM) (molecular weight: 381).

[0086] Commercially available acylphosphine initiators include, for example, Omnirad TPO H (manufactured by IGM) (molecular weight: 348) and Omnirad 819 (manufactured by IGM) (molecular weight: 419).

[0087] Examples of the hydrogen abstraction type radical polymerization initiator include benzophenone-based initiators such as benzophenone, methyl o-benzoylbenzoate, 4-phenylbenzophenone, 4,4'-dichlorobenzophenone, hydroxybenzophenone, 4-benzoyl-4'-methyl-diphenyl sulfide, acrylated benzophenone, 3,3',4,4'-tetra(t-butylperoxycarbonyl)benzophenone, and 3,3'-dimethyl-4-methoxybenzophenone; thioxanthone-based initiators such as 2-isopropylthioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, and 2,4-dichlorothioxanthone; aminobenzophenone-based initiators such as Michler's ketone and 4,4'-diethylaminobenzophenone; 10-butyl-2-chloroacridone, 2-ethylanthraquinone, 9,10-phenanthrenequinone, and camphorquinone.

[0088] Commercially available thioxanthone initiators include 2-isopropylthioxanthone (Speedcure ITX (manufactured by Sartomer) (molecular weight 254)) and 2,4-diethylthioxanthone (Speedcure DETX (manufactured by Sartomer) (molecular weight 268)).

[0089] Examples of cationic polymerization initiators include photoacid generators. Examples of photoacid generators include aromatic onium compounds, such as diazonium, ammonium, iodonium, sulfonium, and phosphonium, of which B(C ６ F ５ ) ４ － , P.F. ６ － , AsF６ － , SbF ６ － , C.F. ３ SO ３ － These include salts, sulfonates that generate sulfonic acid, halides that photogenerate hydrogen halide, and iron-allene complexes.

[0090] The polymerization initiator as component (B) preferably contains thioxanthone, as this further improves the effect of inhibiting discoloration before and after soldering.

[0091] The content of the polymerization initiator as component (B) is preferably within a range of 1 to 10 mass %, and more preferably within a range of 2 to 8 mass %, relative to the total mass of the curable composition for inkjet.

[0092] <Component (C): Triazine Compound> Component (C) is a triazine compound. The inclusion of a triazine compound as component (C) promotes coordination bonding with copper, particularly during soldering, which is performed at higher temperatures than during thermal curing, thereby exhibiting excellent anti-tarnish performance. Therefore, not only in soldering processes using conventionally used eutectic solders, but also in soldering processes using lead-free solders with higher melting points, changes in the anti-tarnish performance of the coating film and the substrate beneath the coating film can be effectively suppressed. Furthermore, when used in combination with a triazole compound as component (D), excellent high-temperature storage stability is also achieved.

[0093] The triazine compound as component (C) is a compound having a triazine skeleton, and in this triazine compound, at least one of the three hydrogen atoms in the triazine ring constituting the triazine skeleton may be substituted with a substituent.

[0094] The triazine compound as component (C) is preferably a compound represented by the following general formula (1), in that it improves the ability to prevent discoloration over time at high temperatures.

[0095]

[0096] However, in the above general formula (1), R １ , R ２ , and R３ are each independently a hydrogen atom, an amino group, or a group represented by the formula (2): -NHR ４ an organic group represented by formula (3): —NR ６ R ７ an organic group other than the above-mentioned substituents or a halogen atom; １ , R ２ , and R ３ At least two of the above are an amino group, an organic group represented by the above formula (2), or an organic group represented by the above formula (3). ４、 R ６、 R ７ is -CH ２ OR ５ , or -COOR ５ is a group represented by R ５ is a hydrogen atom or an alkyl group.

[0097] As described above, R in general formula (1) １ , R ２ , and R ３ each independently represents a hydrogen atom, an amino group, an organic group represented by the above formula (2), an organic group represented by the above formula (3), an organic group other than the above-mentioned substituents, or a halogen atom. １ , R ２ , and R ３ Any organic group that can be a carbon atom number of 1 to 20 is preferred. For example, the arbitrary organic group is preferably an organic group having 1 to 20 carbon atoms, and examples thereof include an alkyl group, a phenyl group, a hydroxyalkyl group, an alkylamino group, a cyano group, a carboxyl group, a hydroxyl group, and an acrylic group. Examples of the alkyl group include a methyl group, an ethyl group, and a propyl group. Examples of the alkylamino group include a methylamino group, an ethylamino group, and a propylamino group.

[0098] When the triazine compound as the component (C) is a compound represented by the general formula (1), from the viewpoint of high-temperature storage stability of the curable composition for inkjet, R １ , R ２ , and R ３ is an amino group (-NH２ Furthermore, from the viewpoint of high-temperature storage stability, it is preferable that R １ , R ２ , and R ３ is more preferably an organic group represented by the above formula (2).

[0099] Examples of the triazine compound as component (C) include the following triazine compounds C-1 to C-4, but the present invention is not limited to these.

[0100]

[0101] The triazine compound C-1 is a tris(alkoxycarbonylamino)triazine, and R １０ is CH ３ , or n-C ４ H ９ An example of a commercially available product of the triazine compound C-1 is Cymel NF-2000A (manufactured by Allnex Co., Ltd.).

[0102] A commercially available product of triazine compound C-2 is Nikalac MW-30HM (manufactured by Sanwa Chemical Co., Ltd.). A commercially available product of triazine compound C-3 is VTMA (manufactured by Shikoku Kasei Co., Ltd.). Triazine compound C-4 is melamine.

[0103] The triazine compound as component (C) may also be an isocyanurate of hexamethylene diisocyanate blocked with a pyrazole compound. For example, it may be a triazine compound (hereinafter also referred to as triazine compound C-5) based on an isocyanurate of 1,6-hexamethylene diisocyanate such as compound C-5A below, using dimethylpyrazole such as compound C-5B below as a blocking agent. An example of a commercially available product of this triazine compound C-5 is BI7982 (manufactured by Lanxess).

[0104]

[0105] The content of the triazine compound as component (C) is preferably within a range of 0.1 to 5 mass %, and more preferably within a range of 0.3 to 3 mass %, relative to the total mass of the curable composition for inkjet. By setting the content of the triazine compound as component (C) within the above range, changes in viscosity, particle size, and discoloration prevention performance over time at high temperatures can be suppressed.

[0106] <Component (D): Triazole Compound> Component (D) is a triazole compound. In the triazole compound as component (D), a benzene ring is not condensed to the triazole ring. By including such a triazole compound as component (D), the discoloration prevention performance over time at high temperatures is improved. In particular, coordination bonding with copper during soldering is promoted, so the discoloration prevention performance during soldering is more effectively improved.

[0107] The triazole compound as component (D) is not particularly limited as long as it is one in which a benzene ring is not condensed with a triazole ring. Examples of the triazole compound as component (D) include 1,2,3-triazole, 1,2,4-triazole, methyl 1,2,4-triazole-3-carboxylate, amitrole, N-(2H-1,2,4-triazol-5-yl)salicylamide, 4-amino-1,2,4-triazole, 3-amino-5-mercapto-1,2,4-triazole, and compounds represented by the following general formula (5):

[0108]

[0109] In the above general formula (5), 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.

[0110] The triazole compound as component (D) preferably does not have a primary amine structure, for example, from the viewpoint of high-temperature storage stability. Furthermore, the triazole compound as component (D) more preferably has a tertiary amine structure, for example, from the viewpoint of high-temperature storage stability. Therefore, the triazole compound as component (D) is more preferably a compound represented by the above general formula (5).

[0111] The content of the triazole compound as component (D) is preferably within a range of 0.1 to 5 mass %, and more preferably within a range of 0.3 to 3 mass %, relative to the total mass of the curable composition for inkjet. By setting the content of the triazine compound as component (D) within the above range, changes in viscosity, particle size, and discoloration prevention performance over time at high temperatures can be suppressed.

[0112] Furthermore, the ratio of the content of the triazole compound as component (D) to the content of the triazine compound as component (C) (component (D) / component (C)) is preferably 0.2 to 2.0, more preferably 0.5 to 1.5. By keeping the content ratio of components (C) to (D) within the above range, changes in viscosity, particle size, and discoloration prevention performance over time at high temperatures can be more effectively suppressed.

[0113] The curable composition for inkjet preferably contains a wax, particularly from the viewpoint of suppressing precipitation over time at high temperatures. When the curable composition for inkjet contains a wax, the hydrophobicity of the curable composition for inkjet is increased, and therefore the water absorption of the curable composition for inkjet can be further suppressed. This makes it possible to suppress hydrolysis of the polymerizable compound contained in the curable composition for inkjet, and to suppress the occurrence of precipitation over time at high temperatures. The type of wax is not particularly limited, but from the viewpoint of suppressing precipitation over time at high temperatures, it is more preferable to include, for example, at least one wax selected from the group consisting of ester waxes and ketone waxes.

[0114] The wax is preferably a wax having an organic group with a carbon number of 12 to 60, and more preferably a wax having an organic group with a carbon number of 25 to 45. When a wax having an organic group with such a carbon number is further contained, the generation of precipitates over time at high temperatures can be suppressed, and this is preferable in terms of solubility with other components.

[0115] Examples of aliphatic ketones include dilignoceryl ketone, dibehenyl ketone, distearyl ketone, dieicosyl ketone, dipalmityl ketone, dilauryl ketone, dimyristyl ketone, myristyl palmityl ketone, and palmityl stearyl ketone.

[0116] Examples of fatty esters include fatty acid esters of monoalcohols such as behenyl behenate, icosyl icosanoate, stearyl stearate, palmityl stearate, myristyl myristate, cetyl myristate, and oleyl palmitate; and fatty acid esters of polyhydric alcohols such as glycerin fatty acid esters, sorbitan fatty acid esters, propylene glycol fatty acid esters, ethylene glycol fatty acid esters, and polyoxyethylene fatty acid esters.

[0117] Examples of commercially available aliphatic esters include the EMALEX series (manufactured by Nippon Emulsion Co., Ltd. ("EMALEX" is a registered trademark of the company)), the Rikemal series, and the Poem series (manufactured by Riken Vitamin Co., Ltd.). "Rikemal" and "Poem" are both registered trademarks of Riken Vitamin Co., Ltd.

[0118] Examples of higher fatty acids include behenic acid, arachidic acid, stearic acid, palmitic acid, myristic acid, lauric acid, oleic acid, and erucic acid.

[0119] Examples of higher alcohols include stearyl alcohol and behenyl alcohol.

[0120] Among these, from the viewpoint of further suppressing the formation of precipitates, the wax is preferably an aliphatic ketone, an aliphatic ester, a higher fatty acid, or a higher alcohol. The wax is more preferably an aliphatic ketone represented by the following general formula (G1) or an aliphatic ester represented by the following general formula (G2). Only one type of wax may be contained, or two or more types may be contained in combination.

[0121] General formula (G1): R ｃ -CO-R ｄ General formula (G2): R ｅ -COO-R ｆ

[0122] In general formula (G1), R ｃ and R ｄ each independently represents a linear hydrocarbon group having from 12 to 26 carbon atoms, which may have a branched chain. ｅ and R ｆ each independently represents a linear hydrocarbon group having 12 to 26 carbon atoms, which may have a branched chain.

[0123] In general formula (G1) and general formula (G2), R ｃ ~R ｆ When the number of carbon atoms is 12 or more, the hydrophobicity of the waxes represented by general formula (G1) and general formula (G2) is further increased, and therefore the generation of precipitates over time at high temperatures can be further suppressed.

[0124] Also, R ｃ ~R ｆ By making the number of carbon atoms in the wax represented by general formula (G1) or (G2) 26 or less, it is possible to prevent the melting point of the wax represented by general formula (G1) or (G2) from rising excessively, which prevents the solation temperature of the ink containing the wax from rising too high, allowing the ink to be discharged at a lower heating temperature.

[0125] Examples of aliphatic ketones represented by general formula (G1) include dilignoceryl ketone (carbon number: 23-24), dibehenyl ketone (carbon number: 21-22), distearyl ketone (carbon number: 17-18), dieicosyl ketone (carbon number: 19-20), dipalmityl ketone (carbon number: 15-16), dimyristyl ketone (carbon number: 13-14), dilauryl ketone (carbon number: 11-12), lauryl myristyl ketone (carbon number: ketone (number of carbon atoms: 11-14), lauryl palmityl ketone (number of carbon atoms: 11-16), myristyl palmityl ketone (number of carbon atoms: 13-16), myristyl stearyl ketone (number of carbon atoms: 13-18), myristyl behenyl ketone (number of carbon atoms: 13-22), palmityl stearyl ketone (number of carbon atoms: 15-18), palmityl behenyl ketone (number of carbon atoms: 15-22), and stearyl behenyl ketone (number of carbon atoms: 17-22). The number of carbon atoms in the parentheses indicates the number of carbon atoms in each of the two hydrocarbon groups separated by the carbonyl group.

[0126] Examples of commercially available products of the compound represented by general formula (G1) include 18-Pentatriacontanon and Hentriacontan-16-on (both manufactured by Alfa Aeser), and Kaowax T1 (manufactured by Kao Corporation).

[0127] Examples of the aliphatic ester represented by general formula (G2) include behenyl behenate (number of carbon atoms: 21-22), icosanoic acid icosyl (number of carbon atoms: 19-20), stearyl stearate (number of carbon atoms: 17-18), palmityl stearate (number of carbon atoms: 17-16), lauryl stearate (number of carbon atoms: 17-12), cetyl palmitate (number of carbon atoms: 15-16), stearyl palmitate (number of carbon atoms: 15-18), myristyl Myristate (number of carbon atoms: 13-14), myristate (number of carbon atoms: 13-16), octyldodecyl myristate (number of carbon atoms: 13-20), stearyl oleate (number of carbon atoms: 17-18), stearyl erucate (number of carbon atoms: 21-18), stearyl linoleate (number of carbon atoms: 17-18), behenyl oleate (number of carbon atoms: 18-22), and arachidyl linoleate (number of carbon atoms: 17-20). The number of carbon atoms in the parentheses indicates the number of carbon atoms in each of the two hydrocarbon groups separated by the ester group.

[0128] Commercially available examples of the aliphatic ester represented by general formula (G2) include Unistar M-2222SL, Sperm Acetate, Nissan Elector WEP-2, and Nissan Elector WEP-3 (all manufactured by NOF Corporation, "Unistar" and "Nissan Elector" are registered trademarks of the company), Exseparl SS and Exseparl MY-M (both manufactured by Kao Corporation, "Exseparl" 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 Amureps PC (manufactured by Kokyu Alcohol Kogyo Co., Ltd., "Amureps" is a registered trademark of the company). These commercially available products are often mixtures of two or more types, and therefore may be separated and purified as necessary before being incorporated into the ink.

[0129] The wax content is preferably 1 to 10% by mass, and 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, the hydrophobicity of the curable composition for inkjet is increased, thereby further suppressing water absorption of the curable composition for inkjet. When the content is 10% by mass or less, the solubility of the wax in the polymerizable compound can be further increased.

[0130] <Others> The curable composition for inkjet contains a pigment as a colorant within the range in which the effects of the present invention are exhibited.

[0131] (Colorant) The colorant is a dye or a pigment, but a pigment is preferred from the viewpoints of increasing the heat resistance of the colorant and preventing discoloration of the cured film of the composition after aging at high temperatures. The pigment can be selected from, for example, yellow pigments, red pigments, blue pigments, black pigments, and white pigments depending on the color of the image to be formed.

[0132] 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. Of these, PY185 and PY150 are preferred from the viewpoints of increasing the heat resistance of the pigment and preventing discoloration of the cured film.

[0133] 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, and Pigment Violet (PV). Pigment Orange (PO) 13, 16, 20, 36, etc. Among these, PR122 and PV19 are preferred from the viewpoint of increasing the heat resistance of the pigment and preventing discoloration of the cured film.

[0134] Examples of blue 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, and 60. Of these, PB15:3 and PB15:4 are preferred from the viewpoints of increasing the heat resistance of the pigment and preventing discoloration of the cured film.

[0135] Examples of green pigments include C.I. Pigment Green (hereinafter also simply referred to as "PG") 7, PG 26, PG 36, and PG 50.

[0136] Examples of black pigments include C.I. Pigment Black (hereinafter also simply referred to as "PBk") 7, PBk26, and PBk28.

[0137] The white pigment may be any pigment that imparts a white color to the cured film formed by curing the white ink. Examples of the white pigment include inorganic pigments such as titanium oxide, zinc oxide, calcium carbonate, barium sulfate, and aluminum hydroxide. Of these, titanium oxide is preferred.

[0138] The crystalline form of the titanium oxide may be any of rutile, anatase, and brookite, but from the viewpoint of facilitating the reduction of the particle size of the white pigment, the anatase type, which has a low specific gravity, is preferred.Furthermore, from the viewpoint of further improving the concealing properties of the formed image, the crystalline form is preferably rutile, which has a high refractive index in the visible light region.

[0139] The content of the colorant is preferably 0.1 to 10% by mass, and more preferably 0.3 to 5% by mass, relative to the total mass of the curable composition for inkjet. When the colorant is a pigment, from the viewpoint of reducing the amount of impurities in the curable composition for inkjet, the content of the pigment is preferably 20% by mass or less, and more preferably 10% by mass or less, relative to the total mass of the curable composition for inkjet.

[0140] (Pigment Dispersant) When the curable composition for inkjet contains a pigment, the curable composition for inkjet may contain a pigment dispersant.

[0141] Examples of the pigment dispersant include carboxylic acid esters having a hydroxy group, salts of long-chain polyaminoamides and high-molecular-weight acid esters, salts of high-molecular-weight polycarboxylic acids, salts of long-chain polyaminoamides and polar acid esters, high-molecular-weight unsaturated acid esters, polymer copolymers, modified polyurethanes, modified polyacrylates, polyether ester-type anionic surfactants, naphthalenesulfonic acid formalin condensate salts, aromatic sulfonic acid formalin condensate salts, polyoxyethylene alkyl phosphate esters, polyoxyethylene nonylphenyl ether, and stearylamine acetate.

[0142] Examples of commercially available pigment dispersants include the Solsperse (registered trademark) series manufactured by Avecia and the PB series manufactured by Ajinomoto Fine-Techno Co., Ltd.

[0143] The content of the pigment dispersant is preferably within a range of 1 to 50% by mass relative to the mass of the pigment.

[0144] The pigment dispersant is preferably a block copolymer with an amine value of 5 to 100 mgKOH / g. Such a pigment dispersant can improve the dispersion stability of the ink. The amine value of the block copolymer used as the pigment dispersant is more preferably 5 to 100 mgKOH / g, and particularly preferably 10 to 50 mgKOH / g.

[0145] The amine value can be measured by potentiometric titration, for example, by the method described in Journal of the Color Materials Association, 61,

[12] 692-698 (1988).

[0146] The amine value can be determined from the amount of perchloric acid MIBK solution required for neutralization when a solution prepared by dissolving 1 g of the pigment dispersant in 100 mL of methyl isobutyl ketone (MIBK) is subjected to potentiometric titration with a 0.01 mol / L perchloric acid MIBK solution.

[0147] The content of the pigment dispersant is preferably 1 to 50% by mass relative to the mass of the pigment.

[0148] (Surfactant) The curable composition for inkjet may contain a surfactant.

[0149] Examples of surfactants include anionic surfactants such as dialkyl sulfosuccinates, alkyl naphthalene sulfonates, and fatty acid salts. Examples of surfactants also include nonionic surfactants such as polyoxyethylene alkyl ethers, polyoxyethylene alkyl allyl ethers, acetylene glycols, and polyoxyethylene-polyoxypropylene block copolymers. Examples of surfactants also include cationic surfactants such as alkylamine salts and quaternary ammonium salts, as well as silicone-based and fluorine-based surfactants.

[0150] Commercially available examples of 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 BYK-Chemie ("BYK" is a registered trademark of the company)), and TSF4452 (manufactured by Momentive Performance Materials).

[0151] Commercially available examples of fluorine-based surfactants include Megafac F (manufactured by DIC Corporation ("Megafac" is a registered trademark of DIC Corporation)), Surflon (manufactured by AGC Sei Chemical Co., Ltd. ("Surflon" is a registered trademark of AGC Sei Chemical Co., Ltd.)), Fluorad FC (manufactured by 3M Corporation ("Fluorad" is a registered trademark of 3M Corporation)), Monflor (manufactured by Imperial Chemical Industries, Ltd.), Zonyls (manufactured by E.I. duPont Nemelas and Company), Licowet VPF (manufactured by Lubewerke-Hoechst), and FTERGENT (manufactured by Neos Corporation ("FTERGENT" is a registered trademark of 3M Corporation)).

[0152] The content of the surfactant is not particularly limited as long as the effects of the present invention are achieved, but it is preferably, for example, 0.001 to 1.0% by mass relative to the total mass of the curable composition for inkjet.

[0153] (Polymerization inhibitor) From the viewpoint of storage stability, the curable composition for inkjet preferably contains a polymerization inhibitor. The polymerization inhibitor is preferably a thermal polymerization inhibitor. Examples of the thermal polymerization inhibitor include radical polymerization inhibitors.

[0154] Examples of the radical polymerization inhibitor include a phenolic hydroxy group-containing compound, a quinone or hydroquinone, a phenothiazine, an N-oxyl, a nitrosamine, etc. From the viewpoint of improving storage stability at higher temperatures and discoloration prevention performance, the radical polymerization inhibitor is preferably an N-oxyl or a nitrosamine.

[0155] Examples of the phenolic hydroxy group-containing compound include 2,6-di-tert-butylphenol, 2,4-di-tert-butylphenol, 2-tert-butyl-4,6-dimethylphenol, 2,6-di-tert-butyl-4-methylphenol, 2,4,6-tri-tert-butylphenol, 2,6-di-t-butyl-p-cresol (butylated hydroxytoluene: BHT), 4-methoxyphenol, and 2-methoxy-4-methylphenol.

[0156] Examples of quinones or hydroquinones include hydroquinone, methoxyhydroquinone, benzoquinone, 1,4-naphthoquinone, p-tert-butylcatechol, hydroquinone monomethyl ether (MEHQ), and the like.

[0157] N-oxyls (nitroxyl or N-oxyl groups, compounds having at least one >N—O.— group) are, for example, piperidine N-oxyl compounds, preferably piperidine N-oxyl free radical compounds.

[0158] Examples of N-oxyls include 4-hydroxy-2,2,6,6-tetramethyl-piperidine-N-oxyl, 4-oxo-2,2,6,6-tetramethyl-piperidine-N-oxyl, 4-methoxy-2,2,6,6-tetramethyl-piperidine-N-oxyl, 4-acetoxy-2,2,6,6-tetramethyl-piperidine-N-oxyl, 2,2,6,6-tetramethyl-piperidine-N-oxyl, BASF Uvinul 4040P from Aktiengesellschaft, 4,4',4"-tris-(2,2,6,6-tetramethyl-piperidine-N-oxyl)phosphite, 3-oxo-2,2,5,5-tetramethyl-pyrrolidine-N-oxyl, 1-oxyl-2,2,6,6-tetramethyl-4-methoxypiperidine, 1-oxyl-2,2,6,6-tetramethyl-4-trimethylsilyloxypiperidine, 1-oxo-2,2,6,6-tetramethyl-4-methoxypiperidine, 1-oxyl-2,2,6,6-tetramethyl-4-trimethylsilyloxypiperidine, 1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl-2-ethylhexanoate, 1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl-sebacate, 1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl-stearate, 1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl-benzoate, 1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl-(4-t-butyl) benzoate, bis-(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl)succinate, bis-(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl)adipate, 1,10-decanedioic acid-bis-(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl)ester, bis-(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl)n-butylmalonate, bis-( N,N'-bis-(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl)phthalate, bis-(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl)isophthalate, bis-(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl)terephthalate, bis-(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl)hexahydroterephthalate, N,N'-bis-(1-oxyl-2,2,6,Preferred are N-(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl)adipinamide, 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-tris-[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, and 4,4'-ethylene-bis-(1-oxyl-2,2,6,6-tetramethylpiperazin-3-one).

[0159] An example of a commercially available N-oxyl product is Irgastab UV-10 (manufactured by BASF Japan).

[0160] Examples of nitrosamines include salts of N-nitrosophenylhydroxylamine.

[0161] Examples of the salt of N-nitrosophenylhydroxylamine include N-nitrosophenylhydroxylamine ammonium salt and N-nitroso-N-phenylhydroxylamine aluminum (NPHA).

[0162] The content of the polymerization inhibitor is not particularly limited as long as the effects of the present invention are achieved, but it is preferably 0.01 to 1 mass %, and more preferably 0.05 to 0.5 mass %, relative to the total mass of the inkjet ink composition.

[0163] (Antioxidant) An antioxidant may be added to the curable composition for inkjet in order to further enhance the effect of preventing discoloration of the coating film.

[0164] Examples of antioxidants include n-octadecyl-3-(3'5'-di-t-butyl-4'-hydroxyphenyl)-propionate, n-octadecyl-3-(3'-methyl-5'-t-butyl-4'-hydroxyphenyl)-propionate, n-tetradecyl-3-(3'5'-di-t-butyl-4'-hydroxyphenyl)-propionate, 1,6-hexanediol-bis-(3-(3,5-di-t-butyl-4-hydroxyphenyl)-propionate), 1,4-butanediol-bis-(3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate), and 1,4-butanediol-bis-(3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate). N,N'-bis-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate), triethylene glycol-bis-(3-(3-t-butyl-5-methyl-4-hydroxyphenyl)propionate), tetrakis-(methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate methane, 3,9-bis(2-(3-(3-t-butyl-4-hydroxy-5-methylphenyl)propionyloxy)-1,1-dimethylethyl)2,4,8,10-tetraoxaspiro(5,5)undecane, N,N'-bis-3-(3',5'-di-t-butyl-4-hydroxyphenol ) hindered phenols such as propionylhexamethylenediamine, N,N'-tetramethylenebis-3-(3'-methyl-5'-t-butyl-4-hydroxyphenol)propionyldiamine, N,N'-bis-(3-(3,5-di-t-butyl-4-hydroxyphenol)propionyl)hydrazine, N-salicyloyl-N'-salicylidenehydrazine, 3-(N-salicyloyl)amino-1,2,4-triazole, and N,N'-bis(2-(3-(3,5-di-butyl-4-hydroxyphenyl)propionyloxy)ethyl)oxyamide Compounds, didodecyl-3,3'-thiodipropionate, ditetradecyl-3,3'-thiodipropionate, dioctadecyl-3,3'-thiodipropionate, ditridecyl-3,3'-thiodipropionate, pentaerythrityl tetrakis(3-dodecylthiopropionate), pentaerythrityl tetrakis(3-tetradecylthiopropionate), pentaerythrityl tetrakis(3-tridecylthiopropionate), dilauryl-3,3-thiodipropionate, dimyristyl-3,3-thiodipropionate, distearyl-3,sulfur-based antioxidants such as 3-mercaptobenzimidazole, 3-thiodipropionate, pentaerythrityl tetrakis(3-laurylthiodipropionate, 2-mercaptobenzimidazole, laurylstearylthiodipropionate, zinc salt of 2-mercaptomethylbenzimidazole, zinc salt of 2-mercaptobenzimidazole, 2-mercaptomethylbenzimidazole, zinc dibutylthiocarbamate; triphenyl phosphite, tris(methylphenyl)phosphite, tris(methylphenyl)phosphite, Triisooctyl phosphite, tridecyl phosphite, tris(2-ethylhexyl) phosphite, tris(nonylphenyl) phosphite, tris(octylphenyl) phosphite, tris[decylpoly(oxyethylene)phosphite, tris(cyclohexylphenyl) phosphite, tricyclohexyl phosphite, tri(decyl)thiophosphite, triisodecylthiophosphite, phenyl bis(2-ethylhexyl) phosphite phosphorus-based antioxidants such as phenyl diisodecyl phosphite, tetradecylpoly(oxyethylene) bis(ethylphenyl) phosphat, phenyl dicyclohexyl phosphite, phenyl diisooctyl phosphite, phenyl di(tridecyl) phosphite, diphenyl cyclohexyl phosphite, diphenyl isooctyl phosphite, diphenyl 2-ethylhexyl phosphite, diphenyl isodecyl phosphite, diphenyl cyclohexylphenyl phosphite, and 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.

[0165] These antioxidants can be used alone or in combination. Among them, hindered phenol compounds are preferred because of their high discoloration suppressing effect.

[0166] Examples of 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).

[0167] The amount of antioxidant blended 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 curable composition for inkjet. When the amount of antioxidant blended is 0.1 part by mass or more relative to 100 parts by mass of the curable composition for inkjet, the effect of preventing discoloration of the coating film is high. Furthermore, when the amount of antioxidant blended is 5 parts by mass or less relative to 100 parts by mass of the curable composition for inkjet, the storage stability of the curable composition for inkjet and the adhesion of the coating film are good.

[0168] (Deodorant, Fragrance) The curable composition for inkjet 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.

[0169] The deodorant that can be used in the curable composition for inkjet is not particularly limited, but a deodorant that chemically bonds with an amine or an aldehyde is preferred.

[0170] Examples of deodorizers that chemically bond with amines include sarcosine-based compounds such as N-oleoyl sarcosine, and examples of deodorizers that chemically bond with aldehydes include hydrazide-based compounds such as Chemcatch P-9600 and Chemcatch T-6900 (manufactured by Otsuka Chemical Co., Ltd.).

[0171] The fragrance that can be used in the curable composition for inkjet of this embodiment is not particularly limited, and examples thereof include the following (1) to (6).

[0172] (1) Essential oils: grapefruit oil, orange oil, lemon oil, lime oil, nutmeg oil, cassia oil, lavender oil, cypress oil, fennel oil, ylang-ylang oil, chamomile oil, jasmine oil, hiba oil, peppermint oil, lavender oil, rosemary oil, etc.

[0173] (2) Alcohols: hexyl alcohol, phenylethyl alcohol (Rose P), furfuryl alcohol, cyclotene, geraniol, linalool, linalool, 1-menthol, borneol, lambazurol, hexyl alcohol, cyclotene, maltol, eugenol, α-phenylethanol, etc.

[0174] (3) Aldehydes: tetradecanal, hexadecanal, octadecanal, benzaldehyde, furfural, etc.

[0175] (4) Aldehydes: ethyl acetoacetate, propyl acetate, amyl acetate, linalyl acetate, benzyl acetate, dimethylbenzylcarbinyl acetate, benzyl propionate, heptanal, octanal, dodecanal, citral, lyral, cyclamen aldehyde, vanillin, and the like.

[0176] (5) Aromatic compounds: nootkatone, ethylpyrazine, lemon turpeneless, orange turpeneless, vanillin, ethyl vanillin, furfuryl mercaptan, borneol, heliotrope, vanillin, ethyl vanillin, etc.

[0177] (6) Esters: ethyl acetate (ethyl acetate), propyl acetate (propyl acetate), amyl acetate, linalyl acetate, benzyl acetate (benzyl acetate), dimethylbenzyl carbinyl acetate, benzyl propionate, geranyl acetate, and the like.

[0178] Among the fragrances listed in (1) to (6) above, linalool, vanillin, and ethyl vanillin are preferred.

[0179] In the curable composition for inkjet of this embodiment, various blended flavors can be formulated and used, including blended flavors that suitably combine the above-mentioned flavors, such as banana flavor, blueberry flavor, vanilla flavor, mint flavor, apple flavor, peach flavor, melon flavor, pineapple flavor, grape flavor, lilac flavor, and jasmine flavor. Commercially available blended flavors can also be used, such as vanilla flavor (Vanilla BVK-3359 (manufactured by Takasago International Corporation)), mint flavor (Mint THP-8148 (manufactured by Hasegawa International Corporation)), banana flavor (Banana T-1510 (manufactured by Yamamoto International Corporation)), blueberry flavor (Blueberry V-647 (manufactured by Yamamoto International Corporation)), and fennel oil N-3707 (manufactured by Takasago International Corporation).

[0180] The content of these fragrances is in the range of 0.01 to 10% by mass, preferably 0.01 to 5% by mass, relative to the total mass of the curable composition for inkjet. When the content of these fragrances is 0.01% by mass or more, the fragrance can be sensed, and when it is 10% by mass or less, the curability is not affected, which is preferable.

[0181] [Physical Properties] The viscosity of the curable composition for inkjet is preferably 5 to 50 mPa·s, and more preferably 7 to 20 mPa·s, at the temperature at which it is discharged from the inkjet head. Having the viscosity within the above range allows for further improvement in the ejection stability of the ink. From the viewpoint of further improving the dischargeability from the inkjet head, the temperature of the curable composition for inkjet when filled into the inkjet head is preferably set to 40°C or higher and 100°C or lower, and more preferably 40°C or higher and 90°C or lower. In other words, the temperature at which it is discharged from the inkjet head is preferably set to 40°C or higher and 100°C or lower.

[0182] [Method for preparing curable composition for inkjet] The curable composition for inkjet can be prepared by mixing the above-mentioned components. At this time, it is preferable to mix the components while heating in order to increase the solubility of each component.

[0183] Alternatively, a pigment dispersion containing the pigment and the pigment dispersant may be prepared in advance, and the remaining components may be added to the pigment dispersion and mixed in. In this case, the pigment can be dispersed using, for example, a ball mill, a sand mill, an attritor, a roll mill, an agitator, a Henschel mixer, a colloid mill, an ultrasonic homogenizer, a pearl mill, a wet jet mill, or a paint shaker.

[0184] The inkjet curable composition can be used to form a solder resist (insulating film) for electronic components. Therefore, the curable composition can be used, for example, as a solder resist ink for forming a solder resist on a printed wiring board, or as an ink for forming a solder resist on a semiconductor / IC package, an RFID antenna, or the like. The curable composition can also be used as an ink for a semiconductor encapsulant, an ink for an underfill material, an ink for a die bonding material, an ink for a black matrix of an LED or an image display device, an ink for a multilayer substrate prepreg, or the like.

[0185] [Inkjet Recording Method] Next, an embodiment of the inkjet recording method of the present invention will be described. The inkjet recording method of this embodiment is an inkjet recording method in which an inkjet curable composition is ejected onto a substrate and cured by actinic rays. The inkjet recording method of this embodiment is characterized in that the inkjet curable composition of this embodiment described above is used as the inkjet curable composition, and a metal-containing substrate is used as the substrate.

[0186] Specifically, the inkjet recording method of this embodiment includes a step of applying the inkjet curable composition described above to the surface of a substrate, and a step of irradiating the applied curable composition with actinic rays to cure the curable composition. Hereinafter, the step of applying the inkjet curable composition to the surface of a substrate will also be referred to as a "step of applying ink." Furthermore, the step of irradiating the applied curable composition with actinic rays to cure the curable composition includes a step of irradiating with actinic rays and a step of heating. Each of these steps will be described in more detail below.

[0187] (1) Ink applying step: In this step, the inkjet curable composition (hereinafter also simply referred to as "ink") is applied to a substrate by an inkjet method. The method of ejection from the inkjet head may be either an on-demand method or a continuous method. Examples of substrates to which the ink is applied include metal parts of electronic components.

[0188] The on-demand inkjet head may be of an electro-mechanical conversion type, an electro-thermal conversion type, or the like. For example, the inkjet head may be of an electro-mechanical conversion type, such as a single-cavity type, double-cavity type, bender type, piston type, shear mode type, or shared wall type. The inkjet head may also be of an electro-thermal conversion type, such as a thermal inkjet type or a bubble jet type ("Bubble Jet" is a registered trademark of Canon Inc.).

[0189] It is preferable to heat the ink so that the temperature of the ink when filled into the inkjet head is 40° C. or higher. In particular, the temperature of the ink is preferably set to 40 to 100° C., and more preferably 40 to 90° C. By setting the ink temperature in this range, it is possible to further improve the ejection properties from the inkjet head.

[0190] The method for heating the ink is not particularly limited. For example, the ink may be heated by heating at least one of the ink supply system, the piping with a filter, and the piezo head using a panel heater, a ribbon heater, or heated water. The ink supply system includes the ink tank and supply pipe that constitute the head carriage, and the front chamber ink tank immediately before the head.

[0191] The amount of ink droplets ejected is preferably 3.0 to 9.0 pL from the viewpoint of increasing the pattern formation speed and forming a finer pattern.

[0192] Examples of electronic components include printed wiring boards, semiconductor / IC packages, mini micro LEDs, etc. Examples of the substrate, which is the metal part of the electronic component, may contain nickel, aluminum, etc. in addition to copper.

[0193] (2) Step of Irradiating Actinic Rays: In this step, the ink applied to the surface of the substrate is irradiated with actinic rays to cure the ink.

[0194] The actinic 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.

[0195] The ultraviolet light preferably has a peak wavelength of 360 to 410 nm. The ultraviolet light is preferably emitted from an LED light source. LEDs emit less radiant heat than conventional light sources (such as metal halide lamps). Therefore, by using an LED, the ink is less likely to melt when exposed to actinic rays, making it less likely to produce uneven gloss.

[0196] (3) Heating Step: The inkjet recording method of this embodiment may further include a step of heating the substrate at 140° C. or higher. By carrying out this heating step, the hardness of the solder resist is improved.

[0197] The heating temperature of the substrate is preferably 140 to 180° C. The heating time is preferably 30 to 120 minutes, and more preferably 30 to 60 minutes.

[0198] [Solder Resist] Next, an embodiment of the solder resist of the present invention will be described. The solder resist of this embodiment is characterized by containing the curable composition for inkjet of this embodiment described above. That is, the solder resist of this embodiment is formed by irradiating the above-mentioned curable composition for inkjet with actinic rays. The solder resist can be formed by the above-mentioned inkjet recording method.

[0199] The electrical resistance of the solder resist is 1.0×10 ８ The electrical resistance of the solder resist is 1.0×10８ ~1.0 x 10 １８ Ω, and preferably 1.0×10 １０ ~1.0 x 10 １８ More preferably, the electrical resistance is 1.0×10 １１ ~1.0 x 10 １８ It is preferably Ω.

[0200] [Printed Wiring Board] Next, a printed wiring board using the solder resist of this embodiment will be described. The printed wiring board has the above-described solder resist on a base material (substrate).

[0201] The substrate on which the solder resist is formed can be a base substrate having a conductive film such as copper foil formed thereon. The base substrate includes a rigid substrate and a flexible substrate.

[0202] Examples of rigid substrates include paper phenolic substrates, paper epoxy substrates, glass epoxy substrates, glass polyimide substrates, Teflon (registered trademark) substrates, PPO substrates, composite substrate epoxy substrates, etc. Examples of flexible substrate materials include PET film, polyimide film, etc.

[0203] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these. In the following examples, unless otherwise specified, operations were carried out at room temperature (25°C). Furthermore, unless otherwise specified, "%" and "parts" mean "% by mass" and "parts by mass", respectively.

[0204] [Preparation of Materials] <Component (A): Polymerizable Compound> The compounds shown below were used as the polymerizable compound of component (A).

[0205]

[0206] Hydroxy group-containing polymerizable compound A-13: bisphenol A skeleton-containing epoxy acrylate, EA-1010LC (trade name) manufactured by Shin-Nakamura Chemical Co., Ltd. Hydroxy group-containing polymerizable compound A-14: 2-hydroxy-3-phenoxypropyl acrylate, Epoxy Ester M-600A (trade name) manufactured by Kyoeisha Chemical Co., Ltd. Epoxy group-containing polymerizable compound A-15: bisphenol A type epoxy resin, EPICLONN-695 (trade name) manufactured by DIC Corporation. Epoxy group-containing polymerizable compound A-16: cresol novolac type epoxy resin, EPICLONN 840 (trade name) manufactured by DIC Corporation.

[0207] Dipentaerythritol hexaacrylate. Caprolactone-modified dipentaerythritol hexaacrylate. Propoxylated (3) trimethylolpropane triacrylate. Tricyclodecane dimethanol dimethacrylate. Triethylene glycol dimethacrylate. Hydroxypivalic acid neopentyl glycol diacrylate. Phenoxyethyl acrylate. Dicyclopentenyl acrylate. Dipropylene glycol diacrylate.

[0208] <Component (B): Polymerization Initiator> As the polymerization initiator serving as the component (B), the following polymerization initiators B-1 to B-3 were used.

[0209] Polymerization initiator B-1: Omnirad 907 (manufactured by IGM Resins B.V.) (acetophenone-based initiator, intramolecular cleavage type, α-aminoalkylphenone). Polymerization initiator B-2: Omnirad 819 (manufactured by IGM Resins B.V.) (acylphosphine-based initiator, intramolecular cleavage type, bis(2,4,6-trimethylbenzoyl)-phenyl-phosphine oxide phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide). Polymerization initiator B-3: Speedcure ITX (manufactured by Sartomer) (thioxanthone-based initiator, hydrogen abstraction type, 2-isopropylthioxanthone).

[0210] <Component (C): Triazine Compound> The following triazine compounds C-1 to C-5 were used as the triazine compound serving as component (C). Triazine compound C-5 is a blocked isocyanate compound based on the following compound C-5A (an isocyanurate of 1,6-hexamethylene diisocyanate) and using the following compound C-5B (dimethylpyrazole) as a blocking agent.

[0211]

[0212]

[0213] R in the above triazine compound C-1 １０ is CH ３ , or n-C ４ H ９ The triazine compound C-1 used was Cymel NF-2000A (trade name) manufactured by Allnex Corporation. The triazine compound C-2 used was Nikalac MW-30HM (trade name) manufactured by Sanwa Chemical. The triazine compound C-3 used was VTMA (trade name) manufactured by Shikoku Kasei Corporation. The triazine compound C-4 used was melamine. The triazine compound C-5 refers to a triazine compound based on the compound C-5A and using the compound C-5B as a blocking agent. The triazine compound C-5 used was BI7982 (trade name) manufactured by Lanxess.

[0214] <Component (D): Triazole Compound in Which a Triazole Ring is Not Fused with a Benzene Ring> The following triazole compounds D-1 to D-4 were used as the triazole compound serving as component (D).

[0215]

[0216] As the triazole compound D-1, for example, Irgamet 30 (trade name) manufactured by BASF was used. The triazole compound D-2 was 1,2,4-triazole. The triazole compound D-3 was 1,2,4-triazole-3-methyl carboxylate. The triazole compound D-4 was amitrole.

[0217] <Component (D'): Triazole compound in which a benzene ring is fused to a triazole ring> The following triazole compound D-5 was used as the component (D'). Triazole compound D-5 is a benzotriazole in which a benzene ring is directly fused to a triazole ring.

[0218]

[0219] <Polymerization inhibitor> The following polymerization inhibitors were used: Irgastab UV-10 (manufactured by BASF Japan, N-oxyls) NPHA (N-nitroso-N-phenylhydroxylamine aluminum, nitrosamines).

[0220] <Wax> The following waxes were used: Stearyl stearate (Excepal SS, manufactured by Kao Corporation).

[0221] <Preparation of Pigment Dispersion> (Preparation of Yellow Pigment Dispersion) The following materials were placed in a stainless steel beaker, heated on a hot plate at 65°C for 1 hour, stirred, and dissolved, and then cooled to room temperature. Then, 15.0 parts by mass of yellow pigment PY185 (Paliotol Yellow D1155, manufactured by BASF) was added to the stainless steel beaker. The mixture in the stainless steel beaker and 200 g of zirconia beads (diameter 0.5 mm) were then placed in a glass bottle and sealed. This was dispersed using a paint shaker (5400, manufactured by Red Devil) until the desired particle size was achieved, and the zirconia beads were then removed to prepare a yellow pigment dispersion. Pigment dispersant 1 (EFKA PX4701, manufactured by BASF) 11.2 parts by mass Synergist 1 (Solsperse 22000, manufactured by Lubrizol) 3.0 parts by mass Dispersion medium: dipropylene glycol diacrylate 70.8 parts by mass

[0222] (Preparation of cyan pigment dispersion) A cyan pigment dispersion was prepared in the same manner as the yellow pigment dispersion, except that the amounts of dispersant and dispersion medium used were changed as follows, the pigment added was changed to 23.0 parts by mass of cyan pigment PB15:4 (Chromofine Blue 6332JC, manufactured by Dainichiseika Color & Chemicals Mfg. Co., Ltd.), and Synergist 1 was not added. Note that cyan pigment PB15:4 is a synergist-treated pigment. Pigment dispersant 1 (EFKA PX4701, manufactured by BASF) 7.0 parts by mass Dispersion medium: dipropylene glycol diacrylate 70.0 parts by mass

[0223] The above-mentioned yellow pigment and cyan pigment are pigments that have been subjected to a water washing treatment to reduce the amount of impurities (conductive substances and ionic impurities).

[0224] [Preparation of Inkjet Ink] Example 1: Preparation of Inkjet Ink 1 3.0 parts by mass of yellow pigment dispersion liquid and 3.0 parts by mass of cyan pigment dispersion liquid were mixed, and the following materials were added to the resulting mixture while stirring, to prepare an inkjet ink. (Component (A): Polymerizable Compound) Carboxy group-containing polymerizable compound A-10 5.0 parts by mass Dipentaerythritol hexaacrylate 5.0 parts by mass Caprolactone-modified dipentaerythritol hexaacrylate 5.0 parts by mass Propoxylated (3) trimethylolpropane triacrylate 5.0 parts by mass Tricyclodecane dimethanol dimethacrylate 5.0 parts by mass Triethylene glycol dimethacrylate 5.0 parts by mass Hydroxypivalic acid neopentyl glycol diacrylate 5.0 parts by mass Phenoxyethyl acrylate 5.0 parts by mass Dicyclopentenyl acrylate 5.0 parts by mass Dipropylene glycol diacrylate 36.8 parts by mass (Component (B): Polymerization initiator) Polymerization initiator 1 3.0 parts by mass Polymerization initiator 2 3.0 parts by mass Polymerization initiator 3 3.0 parts by mass (Component (C): Triazine compound) Triazine compound C-1 2.0 parts by mass (Component (D): Triazole compound) Triazole compound D-1 1.0 part by mass (Polymerization inhibitor) Irgastab UV-10 0.1 part by mass NPHA 0.1 part by mass (Wax) Behenyl behenate 1.0 part by mass

[0225] The resulting ink composition was filtered through a 1.0 μm membrane filter (manufactured by ADVANTECH) to obtain inkjet ink 1 (ink No. 1).

[0226] Examples 2 to 21 and Comparative Examples 1 to 3: Preparation of Inkjet Inks 2 to 24 Inkjet inks 2 to 24 (ink Nos. 2 to 24) were obtained in the same manner as in the preparation of inkjet ink 1, except that the materials and amounts of components (A) to (D) were changed so as to obtain ink compositions as shown in Tables 1 to 3 below. In preparing inkjet inks 2 to 24, the materials and amounts of polymerization inhibitors, waxes, and pigment dispersions not shown in Tables 1 to 3 below were the same as in the preparation of inkjet ink 1.

[0227]

[0228]

[0229]

[0230] [Formation of Cured Film] Each prepared ink was loaded into an inkjet recording device having an inkjet recording head equipped with a piezoelectric inkjet nozzle. Next, a voltage was applied to the inkjet recording head so that the droplet ejection volume was 6.0 pL. A 20 mm x 50 mm, 30 μm thick solid pattern and a 30 μm thick, comb-like fine line pattern with a line-and-space of 100 μm and a thickness of 30 μm were formed on a copper-clad laminate for printed wiring boards. An FR-4 substrate (1.6 mm thick, 150 mm x 95 mm) was used as the copper-clad laminate for printed wiring boards. During pattern formation, the ink in the inkjet recording head was heated to 80°C using a built-in heater in the recording head.

[0231] The printed pattern was irradiated with an LED lamp (Fire Jet™ FJ100, manufactured by Phoseon Technology, wavelength 395 nm) at an intensity of 500 mJ / cm ２ The ink layer was cured by irradiating it with ultraviolet light so that the ink layer became

[0232] The copper-clad laminate with the pattern formed thereon was then placed in an oven set to 150°C and heated for 60 minutes to further cure the ink layer, yielding a cured film. The cured films were formed under three conditions: immediately after the ink was prepared; after the ink was stored at 40°C for 1 month and 85°C for 4 days; and after the ink was stored at 40°C for 1 month and 85°C for 8 days. In Tables 4 to 6, the film formed immediately after the ink was prepared is referred to as "ink-ready product." Furthermore, in Tables 4 to 6, the film formed after the ink was stored at 40°C for 1 month and 85°C for 4 days is referred to as "85°C 4-day product," and the film formed after the ink was stored at 40°C for 1 month and 85°C for 8 days is referred to as "85°C 8-day product."

[0233] [Evaluation] <Color Change> In the above [Formation of Cured Film], the solid pattern cured film before being placed in the oven was measured for L by reflected light measurement using a fluorescent spectrodensitometer FD-7 (manufactured by Konica Minolta) under the following conditions. ＊ a ＊ b ＊ Illumination conditions: M0 (A), observation light source: D50, observation conditions: 2° field of view

[0234] In addition, the cured film was heated in an oven at 150°C for 60 minutes and then subjected to the same L ＊ a ＊ b ＊ was measured.

[0235] Furthermore, the cured film after heating in an oven at 150°C for 60 minutes was immersed in a lead-free solder bath at 288°C for 10 seconds three times, and then subjected to the same L ＊ a ＊ b ＊ was measured.

[0236] The ΔE values ​​before and after 60 minutes at 150°C and before and after lead-free soldering were calculated using the following formula and evaluated based on the following criteria, with "A", "B" and "C" being deemed to be no problem in practical use. The cured films formed under the three conditions, immediately after preparation of the ink, after storing the ink at 40°C for 1 month and at 85°C for 4 days, and after storing the ink at 40°C for 1 month and at 85°C for 8 days, were evaluated using the L ＊ a ＊ b ＊ was measured. ΔE = [(ΔL＊ ) ２ + (Δa ＊ ) ２ + (Δb ＊ ) ２ 〕 １／２ (Standards) A: ΔE≦6 B: 6<ΔE≦10 C: 10<ΔE≦15 D: 15<ΔE

[0237] <Adhesion> Grid-like cuts were made in the obtained solid-pattern cured film according to the cross-cut method of JIS K5600-5-6:1999, and adhesive tape was applied. The adhesive tape was peeled off, and the peeling state of the cured film from the substrate was observed to determine the residual adhesion rate. Here, the residual adhesion rate refers to the ratio of the number of squares in which the cured film remained after tape removal to the number of squares created by the cuts. The residual adhesion rate was determined for cured films formed under three conditions: immediately after ink preparation, after storing the ink at 40°C for 1 month and 85°C for 4 days, and after storing the ink at 40°C for 1 month and 85°C for 8 days. The residual adhesion rate was determined for each of the cured films formed under three conditions: immediately after ink preparation, after storing the ink at 40°C for 1 month and 85°C for 8 days, and the adhesion rate was evaluated based on each residual adhesion rate according to the following evaluation criteria. "A," "B," and "C" were determined to be acceptable for practical use. (Criteria) A: The residual adhesion rate was 100%. B: The residual adhesion rate was 80% or more but less than 100%. C: The residual adhesion rate is 60% or more and less than 80%. D: The residual adhesion rate is less than 60%.

[0238] <Hardness (Pencil Hardness)> The surface pencil hardness of each of the prepared cured film samples was measured using a Mitsubishi Pencil Hi-Uni (registered trademark) in accordance with the method described in "JIS Standard K-5400." Specifically, the wood portion of the pencil was scraped off, and the lead was 5 to 6 mm long. A pencil was used in which the tip of the lead was smoothly ground with abrasive paper to obtain a circular cross section. This pencil was held at a 45-degree angle to the sample surface, and the cured film was scratched at a 45-degree angle with a load of 1 kg applied to the sample surface. The pencil hardness was measured for cured films formed under three conditions: immediately after preparing the ink, after storing the ink at 40°C for 1 month and 85°C for 4 days, and after storing the ink at 40°C for 1 month and 85°C for 8 days. The maximum hardness of the pencil, for which the cured film did not reach the recording medium, was evaluated. A maximum pencil hardness of 4H or higher was considered to be within the range acceptable for practical use.

[0239] <Solder Heat Resistance> The heat resistance of the cured film was evaluated as follows. The solid pattern print sample was immersed in a lead-free solder bath at 288°C for 10 seconds three times, and then the residual adhesion rate was calculated using the same method as for "adhesion" described above. The peeling state of the cured film was evaluated according to the following criteria. The residual adhesion rate was calculated for cured films formed under three conditions: immediately after preparing the ink; after storing the ink at 40°C for one month and at 85°C for four days; and after storing the ink at 40°C for one month and at 85°C for eight days. According to the following criteria, "A" and "B" were defined as ranges that are acceptable for practical use. (Criteria) A: Residual adhesion rate is 90% or more and 100%. B: Residual adhesion rate is 90% or more and less than 100%. C: Residual adhesion rate is 70% or more and less than 90%. D: Residual adhesion rate is less than 70%.

[0240] <Plating Resistance> Each sample of the prepared cured film was plated using a commercially available electroless nickel plating bath and electroless gold plating bath under conditions of 0.5 μm nickel and 0.03 μm gold, and a cross-cut tape peel test was performed. Cured films were formed under three conditions: immediately after ink preparation, after storing the ink at 40°C for 1 month and 85°C for 4 days, and after storing the ink at 40°C for 1 month and 85°C for 8 days. The number of remaining cross-cut patterns per 100 was counted and evaluated based on the following criteria. In the criteria below, "A" and "B" were defined as ranges that are acceptable for practical use. (Criteria) A: 100 of 100 remaining patterns. B: 80 to 99 of 100 remaining patterns. C: 60 to 79 of 100 remaining patterns. D: 59 or less of 100 remaining patterns.

[0241] <Viscosity Change> The viscosity of each ink prepared at 80°C was measured using a Physica MCR301 (manufactured by Anton Paar) with a shear rate of 1000 (1 / s). Measurements were taken immediately after the ink was prepared, after storage at 40°C for one month and 85°C for four days, and after storage at 40°C for one month and 85°C for eight days. Hereinafter, "after storage at 40°C for one month and 85°C for four days" will also be referred to simply as "after four days of storage." Furthermore, "after storage at 40°C for one month and 85°C for eight days" will also be referred to simply as "after eight days of storage." The difference in viscosity (viscosity change) between the ink immediately after preparation and after four days of storage, and the difference in viscosity (viscosity change) between the ink immediately after preparation and after eight days of storage were calculated, and the results were evaluated according to the following criteria. In the following criteria, "A," "B," and "C" were defined as ranges acceptable for practical use. (Criteria) A: Viscosity change of less than 0.3 mPa·s. B: Viscosity fluctuation is 0.3 mPa·s or more and less than 0.7 mPa·s. C: Viscosity fluctuation is 0.7 mPa·s or more and less than 1.0 mPa·s. D: Viscosity fluctuation is 1.0 mPa·s or more.

[0242] <Average Particle Size Variation> The average particle size (Z-average) of each ink prepared was measured by dynamic light scattering using a Datasizer Nano ZSP (manufactured by Malvern). The ink was diluted 200 times before measurement. The measurement was carried out at 25°C. Measurements were carried out immediately after the ink was prepared, after storage at 40°C for 1 month and 85°C for 4 days, and after storage at 40°C for 1 month and 85°C for 8 days. Hereinafter, "after storage at 40°C for 1 month and 85°C for 4 days" will also be referred to simply as "after 4 days of storage." Furthermore, "after storage at 40°C for 1 month and 85°C for 8 days" will also be referred to simply as "after 8 days of storage." The difference between the average particle size immediately after the ink was prepared and the average particle size after 4 days of storage (average particle size variation), and the difference between the average particle size immediately after the ink was prepared and the average particle size after 8 days of storage (average particle size variation), were calculated and evaluated according to the following criteria. In the following criteria, "A" and "B" were defined as ranges that are acceptable for practical use. (Criteria) A: Average particle size variation is less than 15 nm. B: Average particle size variation is 15 nm or more and less than 30 nm. C: Average particle size variation is 30 nm or more and less than 50 nm. D: Average particle size variation is 50 nm or more.

[0243]

[0244]

[0245]

[0246] As shown by the above results, the inks of Examples 1 to 21 (Ink Nos. 1 to 21) are able to suppress changes in viscosity, particle size, and discoloration prevention performance over time at high temperatures compared to the inks of Comparative Examples 1 to 3 (Ink Nos. 22 to 24). Furthermore, it was found that the cured films formed using the inks of Examples 1 to 21 have better adhesion, hardness, solder heat resistance, and plating resistance over time at high temperatures compared to the cured films formed using the inks of Comparative Examples 1 to 3.

[0247] According to the present invention, it is possible to provide a curable composition for inkjet that can prevent discoloration of a coating film or a substrate under the coating film during thermal curing and before and after soldering, and that can suppress changes in viscosity, particle size, and discoloration prevention performance over time at high temperatures. Furthermore, according to the present invention, it is possible to provide a solder resist and an inkjet recording method that use the above-mentioned curable composition for inkjet.

Claims

1. A curable composition for inkjet use that contains (A) a polymerizable compound and (B) a polymerization initiator and that cures when exposed to actinic rays, characterized in that it contains (C) a triazine compound and (D) a triazole compound, and that the triazole ring of the triazole compound (D) is not fused with a benzene ring.

2. The curable composition for inkjet according to claim 1, wherein the ratio of the content of the triazole compound (D) to the content of the triazine compound (C) ((D) triazole compound / (C) triazine compound) is 0.2 to 2.

0.

3. The curable composition for inkjet according to claim 1, wherein the triazine compound (C) is a compound represented by the following general formula (1): (However, in the general formula (1), R １ , R ２ , and R ３ are each independently a hydrogen atom, an amino group, or a group represented by the formula (2): -NHR ４ an organic group represented by formula (3): —NR ６ R ７ an organic group represented by the formula (I), an organic group other than the above-mentioned substituents, or a halogen atom; １ , R ２ , and R ３ At least two of the above are an amino group, an organic group represented by the formula (2), or an organic group represented by the formula (3). ４、 R ６、 R ７ is -CH ２ OR ５ , or -COOR ５ is a group represented by R ５ is a hydrogen atom or an alkyl group.

4. R in the general formula (1) １ , R ２ , and R ３ The curable composition for inkjet according to claim 3 , wherein is not an amino group.

5. R in the general formula (1) １ , R ２ , and R ３ and each independently represent an organic group represented by formula (2).

6. The curable composition for inkjet according to claim 1, wherein the triazole compound (D) does not have a primary amine structure.

7. The curable composition for inkjet according to claim 6, wherein the triazole compound (D) has a tertiary amine structure.

8. The curable composition for inkjet according to claim 1, characterized in that the curable composition for inkjet is used as an insulating film in a soldering process using lead-free solder.

9. The curable composition for inkjet recording according to claim 1, further comprising a wax.

10. The curable composition for inkjet according to claim 9, wherein the wax comprises at least one wax selected from the group consisting of ester waxes and ketone waxes.

11. The curable composition for inkjet according to claim 9, wherein the wax has an organic group having 12 to 60 carbon atoms.

12. The curable composition for inkjet printing according to claim 1, further comprising a pigment and a pigment dispersant.

13. The curable composition for inkjet according to claim 12, wherein the pigment dispersant is a block copolymer having an amine value of 5 to 100 mg KOH / g.

14. The curable composition for inkjet recording according to claim 1, further comprising a thermal polymerization inhibitor.

15. The curable composition for inkjet according to claim 1, wherein the polymerizable compound (A) is a polymerizable compound having any one of a carboxy group, a hydroxy group, and an epoxy group.

16. The curable composition for inkjet recording according to claim 1, characterized in that the viscosity at the discharge temperature is 5 to 50 mPa·s.

17. A solder resist comprising the inkjet curable composition according to any one of claims 1 to 16.

18. An inkjet recording method for ejecting an inkjet curable composition onto a substrate and curing it with actinic radiation, characterized in that the inkjet curable composition according to any one of claims 1 to 16 is used as the inkjet curable composition, and a metal-containing substrate is used as the substrate.

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