Curable composition, cured product, and electronic component

Abstract

[Problem] To provide a curable composition having suitable flexibility, suitably low warpage after light exposure, as well as suitable heat resistance for a thin film substrate such as a flexible wiring board. [Solution] A curable composition containing: (A) a radical polymerizable monomer represented by formula 1 (R1 in formula (1) represents a C1-4 hydrocarbon group which may be linear, branched, or cyclic and may include an ether bond (the hydrocarbon group may have a substituent)); (B) a photocurable urethane compound having two (meth)acryloyl groups; (C) a compound other than (A) and (B) having a (meth)acryloyl group; (D) a photopolymerization initiator; and (E) a thermosetting component. The curable composition has low viscosity, and after being coated on a thin film substrate and exposed to light, is capable of keeping warpage of the thin film substrate low. Furthermore, the cured coated film has excellent heat resistance and has both flexibility and low warpage.

Description

[Technical Field]

[0001] The present invention relates to a curable composition, a cured product, and an electronic component, and in particular to a curable composition suitable for inkjet printing, a cured product thereof, and an electronic component having the cured product. [Background technology]

[0002] Flexible printed circuit boards (FPCs) are required to be flexible and heat-resistant because they are mounted in electronic devices, and therefore the solder resist used for FPCs also needs to be flexible and heat-resistant.

[0003] On the other hand, unlike imageable solder resist compositions, there is also a demand for photocurable compositions that can be applied to circuit boards by inkjet printing in order to shorten the manufacturing process for electronic components. When such photocurable compositions are applied to polyimide substrates or other substrates having circuits and exposed to light, the substrates are prone to warping. If the substrate warps in this way, there is a risk that the photocurable composition will not be applied to the appropriate position when a second layer is applied (recoated). Furthermore, if the substrate warps, there is a risk that it will come into contact with the inkjet head. Subsequent thermal curing of the coating film will further warp the substrate. Therefore, photocurable compositions for inkjet printing must be able to suppress warping after exposure.

[0004] As such a composition for inkjet printing, for example, Patent Document 1 discloses a transparent resin composition for forming an insulating film used in inkjet printing, which has excellent bending resistance and coating film strength. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-189532 Summary of the Invention [Problem to be solved by the invention]

[0006] However, although Patent Document 1 discloses that the cured product of the resin composition has excellent bending resistance, no study has been conducted on whether this inkjet ink is improved in warping after exposure when applied to a thin film substrate, particularly a thin polyimide (Kapton 100H), or whether it has sufficient heat resistance, and no measures have been presented to achieve both of these properties.

[0007] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a curable composition that combines flexibility suitable for thin film substrates such as flexible wiring boards, low warpage after exposure, and heat resistance. [Means for solving the problem]

[0008] The present inventors have conducted extensive research to achieve the above object, and as a result, have found that a composition containing a photocurable compound, a photopolymerization initiator, and a thermosetting component, which contains a compound represented by the following general formula (1) and a photocurable urethane compound having two (meth)acryloyl groups as the photocurable compound, can provide a curable composition that exhibits low warpage of a coated substrate after exposure, flexibility, and heat resistance, and has thus completed the present invention.

[0009] That is, the object of the present invention is to (A) Formula (1) [ka] (In formula (1), R 1 represents a hydrocarbon group having 1 to 4 carbon atoms, which may be linear, branched, or cyclic, and which may contain an ether bond (however, the hydrocarbon group may have a substituent). a radical polymerizable monomer represented by the formula: (B) a photocurable urethane compound having two (meth)acryloyl groups; (C) a compound having a (meth)acryloyl group other than (A) and (B); (D) a photopolymerization initiator; (E) a thermosetting component; It has been found that this can be achieved by a curable composition comprising:

[0010] It is also preferred that the composition further contains a flame retardant (F), and the blending amount of the photocurable urethane compound (B) having two (meth)acryloyl groups relative to the flame retardant (F) is preferably 1% by mass or more and 70% by mass or less.

[0011] Furthermore, the blending ratio of (A) the radical polymerizable monomer represented by formula (1) to (B) the photocurable urethane compound having two (meth)acryloyl groups is preferably 250% by mass or more and 10,000% by mass or less.

[0012] Furthermore, the blending ratio of the radical polymerizable monomer (A) represented by formula (1) to the flame retardant (F) is preferably 50% by mass or more and 350% by mass or less.

[0013] Furthermore, it is preferable that the (E) thermosetting component contains a latent thermosetting component, and it is more preferable that the latent thermosetting component is a blocked isocyanate compound.

[0014] Furthermore, the (F) flame retardant is preferably a phosphorus-based flame retardant, and more preferably, the phosphorus-based flame retardant is phenoxyphosphazene.

[0015] Furthermore, the curable composition preferably has a viscosity of 50 mPa·s or less at 50°C.

[0016] Furthermore, the above-mentioned object of the present invention can also be achieved by a cured product obtained from the curable composition of the present invention, and an electronic part having the cured product. [Effects of the Invention]

[0017] The curable composition of the present invention has a low viscosity and can suppress warpage of a thin film substrate after coating on the thin film substrate and exposing to light. Furthermore, the cured coating film has excellent heat resistance and exhibits both low warpage and flexibility. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 2 is an explanatory diagram of an MIT test performed on a cured film obtained from a curable composition. DETAILED DESCRIPTION OF THE INVENTION

[0019] <Curable composition> The curable composition of the present invention comprises: (A) Formula (1) [ka] (In formula (1), R 1 represents a hydrocarbon group having 1 to 4 carbon atoms, which may be linear, branched, or cyclic, and which may contain an ether bond (however, the hydrocarbon group may have a substituent). (hereinafter also referred to as the radical polymerizable monomer of formula (1) (A)) (B) a photocurable urethane compound having two (meth)acryloyl groups; (C) a compound having a (meth)acryloyl group other than (A) and (B); (D) a photopolymerization initiator; (E) a thermosetting component; The curable composition contains:

[0020] [(A) Radical polymerizable monomer of formula (1)] The radical polymerizable monomer of formula (1) (A) contained in the curable composition of the present invention is, for example, a monomer represented by the following formula a): [ka] (Formula a), R 1 is R in equation (1). 1 where X represents an initiating or propagating radical), the polymerization reaction proceeds with cyclization, making it possible to form a main chain skeleton with repeating units of a five-membered ring ether structure with methylene groups on both sides.

[0021] Examples of the hydrocarbon group having 1 to 4 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, a tert-butyl group, a vinyl group, an allyl group, a methallyl group, a crotyl group, a cyclopropyl group, a cyclobutyl group, a methoxymethyl group, a methoxyethyl group, an ethoxymethyl group, an ethoxyethyl group, and a vinyloxyethyl group.

[0022] Examples of the substituent include chain unsaturated hydrocarbon groups such as vinyl, allyl, methallyl, and crotyl groups; alkoxy groups such as methoxy, ethoxy, and methoxyethoxy groups; alkylthio groups such as methylthio and ethylthio groups; acyl groups such as acetyl and propionyl groups; acyloxy groups such as acetyloxy and propionyloxy groups; alkoxycarbonyl groups such as methoxycarbonyl and ethoxycarbonyl groups; alkylthiocarbonyl groups such as methylthiocarbonyl and ethylthiocarbonyl groups; halogen atoms such as fluorine, chlorine, bromine, and iodine atoms; ureido groups; amide groups; cyano groups; hydroxyl groups; and trimethylsilyl groups.

[0023] R 1From the viewpoints of industrial ease of production of the radical polymerizable monomer of formula (A) (1) and of reducing the viscosity of the radical polymerizable monomer of formula (A) (1) and of reducing the viscosity of the curable composition, preferred are linear saturated hydrocarbon groups having from 1 to 4 carbon atoms, linear unsaturated hydrocarbon groups having from 1 to 4 carbon atoms, and hydrocarbon groups having from 1 to 4 carbon atoms and an ether bond, with methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, allyl, methallyl, crotyl, methoxyethyl, ethoxyethyl, and vinyloxyethyl groups being more preferred, linear saturated hydrocarbon groups having from 1 to 4 carbon atoms such as methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, and tert-butyl groups being even more preferred, with methyl, ethyl, n-propyl, isopropyl, and tert-butyl groups being particularly preferred.

[0024] (A) Examples of the radical polymerizable monomer of formula (1) include methyl α-allyloxymethylacrylate, ethyl α-allyloxymethylacrylate, n-propyl α-allyloxymethylacrylate, isopropyl α-allyloxymethylacrylate, n-butyl α-allyloxymethylacrylate, sec-butyl α-allyloxymethylacrylate, tert-butyl α-allyloxymethylacrylate, vinyl α-allyloxymethylacrylate, allyl α-allyloxymethylacrylate, methallyl α-allyloxymethylacrylate, crotyl α-allyloxymethylacrylate, methoxymethyl α-allyloxymethylacrylate, methoxyethyl α-allyloxymethylacrylate, methoxypropyl α-allyloxymethylacrylate, methoxybutyl α-allyloxymethylacrylate, ethoxymethyl α-allyloxymethylacrylate, ethoxyethyl α-allyloxymethylacrylate, vinyloxyethyl α-allyloxymethylacrylate, etc. These may be used alone or in combination of two or more.

[0025] Among these, methyl α-allyloxymethylacrylate, ethyl α-allyloxymethylacrylate, n-propyl α-allyloxymethylacrylate, isopropyl α-allyloxymethylacrylate, n-butyl α-allyloxymethylacrylate, sec-butyl α-allyloxymethylacrylate, tert-butyl α-allyloxymethylacrylate, allyl α-allyloxymethylacrylate, methallyl α-allyloxymethylacrylate, crotyl α-allyloxymethylacrylate, methoxyethyl α-allyloxymethylacrylate, ethoxyethyl α-allyloxymethylacrylate, glycidyl α-allyloxymethylacrylate, and vinyloxyethyl α-allyloxymethylacrylate are preferred, and α-allyloxymethylacrylate is more preferred. Methyl α-allyloxymethylacrylate, ethyl α-allyloxymethylacrylate, n-propyl α-allyloxymethylacrylate, isopropyl α-allyloxymethylacrylate, n-butyl α-allyloxymethylacrylate, sec-butyl α-allyloxymethylacrylate and tert-butyl α-allyloxymethylacrylate are preferred, methyl α-allyloxymethylacrylate, ethyl α-allyloxymethylacrylate, n-propyl α-allyloxymethylacrylate, isopropyl α-allyloxymethylacrylate and tert-butyl α-allyloxymethylacrylate are more preferred, and methyl α-allyloxymethylacrylate and ethyl α-allyloxymethylacrylate are even more preferred.

[0026] The radical polymerizable monomer of formula (A) (1) can be prepared, for example, according to the methods described in JP-A Nos. 2014-040585 and 2011-137123.

[0027] The blending ratio of the radical polymerizable monomer (A) of formula (1) to the photocurable urethane compound (B) having two (meth)acryloyl groups described below is preferably 250% by mass or more and 10,000% by mass or less, and particularly preferably 300% by mass or more and 5,000% by mass or less. Within this range, the viscosity of the curable resin composition can be maintained low, and the curable resin composition exhibits excellent low warpage after exposure.

[0028] Furthermore, when the curable composition contains a flame retardant (F) described later, the blending ratio of the radical polymerizable monomer of formula (1) (A) is preferably 50% by mass or more and 350% by mass or less, and particularly preferably 65% ​​by mass or more and 250% by mass or less, relative to the flame retardant (F). Within this range, the viscosity of the curable resin composition can be maintained low, while the curable resin composition exhibits excellent low warpage after exposure and excellent flame retardancy.

[0029] [(B) Photocurable urethane compound having two (meth)acryloyl groups] The curable composition of the present invention contains (B) a photocurable urethane compound having two (meth)acryloyl groups. (B) The photocurable urethane compound having two (meth)acryloyl groups imparts flexibility to the cured product of the curable composition of the present invention and also suppresses warping of the substrate after application to a thin film substrate and exposure to light.

[0030] (B) Photocurable urethane compound having two (meth)acryloyl groups has two (meth)acryloyl groups, and therefore has superior properties such as heat resistance and flexibility compared to photocurable urethane compounds having one or less (meth)acryloyl groups, and has superior low warpage and flexibility after exposure compared to photocurable urethane compounds having three or more (meth)acryloyl groups.

[0031] Furthermore, from the viewpoint of keeping the viscosity of the curable composition of the present invention low, the viscosity of the photocurable urethane compound (B) having two (meth)acryloyl groups at 25°C is preferably 20,000 mPa s or less, and particularly preferably 15,000 mPa s or less.

[0032] In the present invention, the viscosity is a value measured in accordance with the viscosity measurement method using a cone-plate rotational viscometer of JIS Z8803:2011, 10, at 100 rpm for 30 seconds using a cone-plate viscometer (TVE-33H, manufactured by Toki Sangyo Co., Ltd.) with a 1°34' x R24 cone rotor.

[0033] Similarly, from the viewpoint of keeping the viscosity of the curable composition of the present invention low, the weight average molecular weight (Mw) of the photocurable urethane compound (B) having two (meth)acryloyl groups is preferably 6,000 or less, and particularly preferably 2,000 or less.

[0034] (B) Examples of photocurable urethane compounds having two (meth)acryloyl groups include UA-112P, UA-4200, UA-4400, UA-160™, UA-122P, and UA-W2 (all manufactured by Shin-Nakamura Chemical Co., Ltd.), CN962, CN963, CN964, CN965, CN980, CN981, CN982, CN983, CN996, CN9001, CN9002, CN9788, CN9893, CN978, CN9782, and CN9783 (all manufactured by Sartomer Corporation), M-1100, and M- 1200, M-1210, M-1310, M-1600 (manufactured by Toagosei Chemical Industry Co., Ltd.), UN-9000PEP, UN-9200A, UN-7600, UN-333, UN-1255, UN-6060PTM, UN-6060P, UN-6200 (manufactured by Negami Chemical Industrial Co., Ltd.), AH-600, AT-600 (all manufactured by Kyoeisha Chemical Co., Ltd.), Ebecryl 280, Ebecryl 284, Ebecryl 8402, Ebecryl 8411, Ebecryl 8807, Ebecryl 9270 (manufactured by Daicel-Allnex Corporation), and the like.

[0035] The blending ratio of (B) the photocurable urethane compound having two (meth)acryloyl groups is, for example, 0.1 to 30 mass %, and preferably 0.5 to 20 mass %, based on the total mass of the curable resin composition.

[0036] When the flame retardant (F) is contained, the blending ratio of the photocurable urethane compound (B) having two (meth)acryloyl groups is from 1% by mass to 70% by mass, preferably from 10% by mass to 50% by mass, and particularly preferably from 10% by mass to 40% by mass, relative to the flame retardant (F).

[0037] [(C) Compounds other than (A) and (B) having a (meth)acryloyl group] The curable composition of the present invention contains (C) a compound having a (meth)acryloyl group other than (A) and (B). (C) a compound having a (meth)acryloyl group other than (A) and (B) is a component that is cured after exposure and incorporated into a cured product. In this specification, a compound having a (meth)acryloyl group other than (C) (A) and (B) may be abbreviated as "(C) a compound having a (meth)acryloyl group."

[0038] (C) The compound having a (meth)acryloyl group has a (meth)acryloyl group as a photopolymerizable group. Here, the term "(meth)acryloyl group" collectively refers to an acryloyl group and a methacryloyl group.

[0039] The (C) compound having a (meth)acryloyl group has one or more (meth)acryloyl groups and may further have, optionally, a functional group or structural moiety such as a hydroxyl group, an ether bond, a ketone, an aromatic ring, a heterocyclic ring, etc. Examples of the (C) compound having a (meth)acryloyl group that can be contained in the curable composition of the present invention are given below, but the (C) compound having a (meth)acryloyl group is not limited to these exemplified compounds.

[0040] (C1) Compounds having one (meth)acryloyl group The compound (C) having a (meth)acryloyl group includes, for example, a compound (C1) having one (meth)acryloyl group. The compound (C1) having one (meth)acryloyl group preferably has, for example, a specific functional group other than a (meth)acryloyl group (preferably a hydroxyl group). When the compound (C1) having one (meth)acryloyl group has the specific functional group, the compound (C1) having one (meth)acryloyl group is incorporated into a cured product after exposure of the curable composition of the present invention, thereby introducing the specific functional group into the cured product. When the specific functional group is introduced into the cured product in this way, various physical properties of the cured product can be further improved.

[0041] The compound (C1) having one (meth)acryloyl group is more preferably a compound having a (meth)acryloyl group and a hydroxyl group, and when a compound having a (meth)acryloyl group and a hydroxyl group is blended into the curable composition of the present invention, the adhesion of the obtained cured film to a conductor and a substrate is improved.

[0042] Examples of compounds having a (meth)acryloyl group and a hydroxyl group include 2-hydroxy-3-acryloyloxypropyl (meth)acrylate, 2-hydroxy-3-phenoxyethyl (meth)acrylate, 1,4-cyclohexanedimethanol mono(meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol monohydroxypenta(meth)acrylate, 2-hydroxypropyl (meth)acrylate, etc. Commercially available products include Aronix M-5700 (trade name, manufactured by Toagosei Co., Ltd.), 4HBA, 2HEA, CHDMMA (all trade names, manufactured by Kyoeisha Chemical Co., Ltd.), BHEA, HPA, HEMA, HPMA (all trade names, manufactured by Nippon Shokubai Co., Ltd.), Light Ester HO, Light Ester HOP, Light Ester HOA (all trade names, manufactured by Kyoeisha Chemical Co., Ltd.), etc. The compound having a (meth)acryloyl group and a hydroxyl group can be used alone or in combination of two or more kinds.

[0043] Among these, 2-hydroxy-3-acryloyloxypropyl acrylate, 2-hydroxy-3-phenoxyethyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 4-hydroxybutyl acrylate, and 1,4-cyclohexanedimethanol monoacrylate are particularly preferred. Furthermore, from the viewpoint of ease of viscosity adjustment, compounds having no aromatic ring are preferably used.

[0044] When the compound (C1) having one (meth)acryloyl group is blended in the curable composition of the present invention, the blending amount thereof is preferably 1 part by mass or more and 15 parts by mass or less, more preferably 1 part by mass or more and 10 parts by mass or less, and particularly preferably 2 parts by mass or more and 5 parts by mass or less, per 100 parts by mass of the curable composition of the present invention.

[0045] (C2) Compounds having two (meth)acryloyl groups (C) Compounds having a (meth)acryloyl group include, for example, (C2) compounds having two (meth)acryloyl groups.

[0046] The compound (C2) having two (meth)acryloyl groups is preferably a photocurable diluent, i.e., a component that dilutes the curable composition to contribute to reducing its viscosity, and that is cured after exposure to light and is incorporated into the cured product.

[0047] When the compound (C2) having two (meth)acryloyl groups is a photocurable diluent, from the viewpoint of diluting the curable composition of the present invention to reduce its viscosity, the viscosity at 50°C is less than 50 mPa s, preferably less than 30 mPa s, and particularly preferably 15 mPa s or less at 50°C.

[0048] An example of the (C2) compound having two (meth)acryloyl groups and having a viscosity at 50°C of less than 50 mPa·s is a bifunctional (meth)acryloyl group-containing monomer that is an ester of alkylene glycol and (meth)acrylic acid.

[0049] The alkylene glycol may be a monoalkylene glycol or may have a repeating structure of two or more alkylene glycols. Examples of the monoalkylene glycol include linear or branched alkylene diols having 3 to 16 carbon atoms, preferably 6 to 9 carbon atoms.

[0050] Examples of the alkylene glycol having a repeating structure of two or more alkylene glycols include diethylene glycol, dipropylene glycol, dibutylene glycol, triethylene glycol, tripropylene glycol, and tributylene glycol.

[0051] Specifically, (C2) compounds having two (meth)acryloyl groups and having a viscosity of less than 50 mPa·s at 50°C include diethylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, dibutylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, tributylene glycol di(meth)acrylate, 1,3-butylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol acrylate, 1,10-decanediol diacrylate, and 1,16-hexadecanediol diacrylate.

[0052] Commercially available (C2) compounds having two (meth)acryloyl groups and having a viscosity of less than 50 mPa·s at 50°C include 2G (manufactured by Shin-Nakamura Chemical Co., Ltd.), 3G (manufactured by Shin-Nakamura Chemical Co., Ltd.), DPGDA (manufactured by Daicel-Allnex Corporation), T0948 (manufactured by Tokyo Chemical Industry Co., Ltd.), T2389 (manufactured by Tokyo Chemical Industry Co., Ltd.), Viscoat #310HP (manufactured by Osaka Organic Chemical Industry Co., Ltd.), PE-200 (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.), PE-300 (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.), HDDA (manufactured by Daicel-Allnex Corporation), L-C9A (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.), A-NOD-N (manufactured by Shin-Nakamura Chemical Co., Ltd.), B1065 (manufactured by Tokyo Chemical Industry Co., Ltd.), and 1,9-NDA (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.).

[0053] When a (C2) compound having two (meth)acryloyl groups and having a viscosity at 50°C of less than 50 mPa s is blended into the curable composition of the present invention, the blending amount thereof is, for example, 2 parts by mass or more and 50 parts by mass or less, preferably 6 parts by mass or more and 40 parts by mass or less, and more preferably 10 parts by mass or more and 30 parts by mass or less, relative to 100 parts by mass of the curable composition of the present invention.

[0054] By setting the blending amount of the (C2) compound having two (meth)acryloyl groups and having a viscosity of less than 50 mPa s at 50°C to 2 parts by mass or more and 50 parts by mass or less per 100 parts by mass of the curable composition of the present invention, the viscosity of the curable composition can be maintained at a low viscosity, and after photocuring, i.e., exposure to light, the (C2) compound having two (meth)acryloyl groups and having a viscosity of less than 50 mPa s at 50°C will be incorporated into the cured product.

[0055] (C3) Compounds that do not have an aromatic ring and have three or more (meth)acryloyl groups (C) Compounds having a (meth)acryloyl group include, for example, compounds having no (C3) aromatic ring and having three or more (meth)acryloyl groups.

[0056] When the curable composition of the present invention contains a compound having no aromatic ring (C3) and three or more (meth)acryloyl groups, the curability upon exposure to light is further improved while suppressing an increase in viscosity of the curable composition of the present invention.

[0057] (C3) Examples of the compound having no aromatic ring and three or more (meth)acryloyl groups include trimethylolpropane triacrylate, trimethylolmethane triacrylate, ethylene oxide-modified trimethylolpropane triacrylate, propylene oxide-modified trimethylolpropane triacrylate, epichlorohydrin-modified trimethylolpropane triacrylate, pentaerythritol tetraacrylate, tetramethylolmethane tetraacrylate, ethylene oxide-modified phosphate triacrylate, propylene oxide-modified phosphate triacrylate, epichlorohydrin-modified glycerol triacrylate, dipentaerythritol hexaacrylate, ditrimethylolpropane tetraacrylate, and polyfunctional acrylates such as silsesquioxane-modified products thereof, or corresponding methacrylate monomers, and ε-caprolactone-modified trisacryloxyethyl isocyanurate.

[0058] The compound having three or more (meth)acryloyl groups may be a multi-branched oligomer or polymer.

[0059] When the (C3) compound having no aromatic ring and three or more (meth)acryloyl groups is blended in the curable composition of the present invention, the blending amount thereof is preferably 1 part by mass or more and 40 parts by mass or less, more preferably 5 parts by mass or more and 20 parts by mass or less, per 100 parts by mass of the curable composition of the present invention.

[0060] (C4) Compounds having an aromatic ring and two or more (meth)acryloyl groups (C) Compounds having a (meth)acryloyl group include, for example, compounds having a (C4) aromatic ring and two or more (meth)acryloyl groups.

[0061] When the curable composition of the present invention contains a compound having a (C4) aromatic ring and two or more (meth)acryloyl groups, the curability upon exposure to light is further improved, and the presence of the aromatic ring in the compound contributes to further improvements in the properties of the cured film (cured product), such as heat resistance and flame retardancy. The compound having a (C4) aromatic ring and two or more (meth)acryloyl groups has a relatively high viscosity (i.e., a viscosity of 50 mPa·s or more at 50°C) due to the aromatic ring. Furthermore, from the viewpoint of suppressing an increase in the viscosity of the curable composition while maintaining good photocurability, it is preferable that the number of (meth)acryloyl groups per molecule of this compound be two.

[0062] (C4) Examples of compounds having an aromatic ring and two or more (meth)acryloyl groups include (meth)acrylates of polyhydric phenols and alkylene oxide adducts thereof.

[0063] Examples of polyhydric phenols include bisphenols such as bisphenol A, bisphenol AP, bisphenol B, bisphenol BP, bisphenol E, bisphenol F, bisphenol M, bisphenol P, bisphenol PH, and bisphenol Z, and biphenols.

[0064] Examples of alkylene oxides include ethylene oxide, propylene oxide, and butylene oxide. The number of alkylene oxides added is preferably 6 or less.

[0065] Commercially available compounds having a (C4) aromatic ring and two or more (meth)acryloyl groups include ABE-300 (manufactured by Shin-Nakamura Chemical Co., Ltd.), BPE-80N (manufactured by Shin-Nakamura Chemical Co., Ltd.), BPE-100 (manufactured by Shin-Nakamura Chemical Co., Ltd.), A-BPE-4 (manufactured by Shin-Nakamura Chemical Co., Ltd.), BPE-4 (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.), BPE-10 (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.), A-BPE-10 (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.), BPE-200 (manufactured by Shin-Nakamura Chemical Co., Ltd.), and EBECRYL 150 (manufactured by Daicel-Allnex Corporation).

[0066] When the (C4) compound having an aromatic ring and two or more (meth)acryloyl groups is blended in the curable composition of the present invention, the blending amount thereof is preferably 1 part by mass or more and 40 parts by mass or less, more preferably 5 parts by mass or more and 20 parts by mass or less, per 100 parts by mass of the curable composition of the present invention.

[0067] The curable composition of the present invention preferably contains, as the (C) compound having a (meth)acryloyl group other than (A) and (B), (C2) a compound having two (meth)acryloyl groups, and particularly preferably contains (C2) a compound having two (meth)acryloyl groups and having a viscosity at 50°C of less than 50 mPa s.

[0068] [(D) Photopolymerization initiator] As the (D) photopolymerization initiator, any compound that generates radicals when exposed to light, a laser, an electron beam, or the like, and initiates a radical polymerization reaction can be used. Examples of the (D) photopolymerization initiator include benzoin and benzoin alkyl ethers such as benzoin, benzoin methyl ether, benzoin ethyl ether, and benzoin isopropyl ether; acetophenones such as acetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, and 1,1-dichloroacetophenone; aminoacetophenones such as 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butan-1-one, and N,N-dimethylaminoacetophenone; anthraquinones such as 2-methylanthraquinone, 2-ethylanthraquinone, 2-t-butylanthraquinone, and 1-chloroanthraquinone; 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2-chlorothioxanthone, and 2,4-diisopropylthioxanthone; thiol compounds such as 2-mercaptobenzimidazole, 2-mercaptobenzoxazole, and 2-mercaptobenzothiazole; organic halogen compounds such as 2,2,2-tribromoethanol and tribromomethylphenyl sulfone; benzophenones or xanthones such as benzophenone and 4,4'-bisdiethylaminobenzophenone; 2,4,6-trimethylbenzoyldiphenylphosphine oxide; and oxime esters such as 1,2-octanedione, 1-[4-(phenylthio)-, 2-(O-benzoyloxime)], ethanone, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-, 1-(O-acetyloxime).

[0069] The (D) photopolymerization initiator can be used alone or in combination of two or more. In addition to these, photoinitiator assistants such as N,N-dimethylaminobenzoic acid ethyl ester, N,N-dimethylaminobenzoic acid isoamyl ester, pentyl-4-dimethylaminobenzoate, triethylamine, triethanolamine, and other tertiary amines can also be used. Titanocene compounds with absorption wavelengths in the visible light region, such as Omnirad 784 (manufactured by IGM Resins BV), can also be added as (D) photopolymerization initiators to promote the photocuring reaction. The components added as photopolymerization initiators are not limited to these, and any compound that absorbs light in the ultraviolet or visible light region and initiates radical polymerization of ethylenically unsaturated groups such as (meth)acryloyl groups can be used alone or in combination. These compounds are not limited to known photopolymerization initiators or photoinitiator assistants.

[0070] The blending amount of the (D) photopolymerization initiator is preferably 0.2 parts by mass or more and 15 parts by mass or less, more preferably 1 part by mass or more and 8 parts by mass or less, relative to 100 parts by mass of the curable composition of the present invention.

[0071] Examples of commercially available (D) photopolymerization initiators include Omnirad 907, Omnirad 127, Omnirad 379EG, and Omnirad 379EG (all manufactured by IGM Resins BV).

[0072] [(E) Thermosetting component] The curable composition of the present invention also contains a thermosetting component (E), which can further improve the functionality of the cured film, such as heat resistance and plating resistance, in addition to reducing warpage of the substrate after application of the curable composition and exposure to light and improving the flame retardancy of the cured film.

[0073] As the (E) thermosetting component, for example, known compounds such as blocked isocyanate compounds, epoxy compounds, and oxetane compounds can be used.

[0074] Among these, in the present invention, it is particularly preferred that the (E) thermosetting component contains a latent thermosetting component in which functional groups in the structure are protected by protecting groups. The inclusion of such a latent thermosetting component can suppress unintended reactions in the curable composition due to unexpected conditions, thereby improving the storage stability of the curable composition. Furthermore, such a curable composition also exhibits excellent inkjet printability at 50°C, and when a reaction is desired, the thermosetting component can be easily deprotected by heating or the like to activate it. In the present invention, "latent" refers to a property that is not active at room temperature or under slightly elevated temperatures, but is activated and thermosetting when heated at high temperatures of 80°C or higher.

[0075] Among these, the latent thermosetting component is preferably a blocked isocyanate compound. The blocked isocyanate compound is a compound having preferably a plurality of blocked isocyanate groups in one molecule. The blocked isocyanate group is a group in which an isocyanate group is protected and temporarily inactivated by reaction with a blocking agent, and when heated to a predetermined temperature, the blocking agent dissociates to generate an isocyanate group.

[0076] As the polyisocyanate compound having a plurality of isocyanate groups, for example, an aromatic polyisocyanate, an aliphatic polyisocyanate, or an alicyclic polyisocyanate can be used.

[0077] Specific examples of aromatic polyisocyanates include 4,4'-diphenylmethane diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, naphthalene-1,5-diisocyanate, o-xylylene diisocyanate, m-xylylene diisocyanate, and 2,4-tolylene dimer.

[0078] Specific examples of aliphatic polyisocyanates include tetramethylene diisocyanate, hexamethylene diisocyanate, methylene diisocyanate, trimethylhexamethylene diisocyanate, 4,4-methylenebis(cyclohexyl isocyanate), and isophorone diisocyanate.

[0079] Specific examples of alicyclic polyisocyanates include bicycloheptane triisocyanate, as well as adducts, biuret compounds, and isocyanurates of the isocyanate compounds listed above.

[0080] Examples of isocyanate blocking agents include phenol-based blocking agents such as phenol, cresol, xylenol, chlorophenol, and ethylphenol; lactam-based blocking agents such as ε-caprolactam, δ-valerolactam, γ-butyrolactam, and β-propiolactam; active methylene-based blocking agents such as ethyl acetoacetate and acetylacetone; and alkoxyl-based blocking agents such as methanol, ethanol, propanol, butanol, amyl alcohol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, propylene glycol monomethyl ether, benzyl ether, methyl glycolate, butyl glycolate, diacetone alcohol, methyl lactate, and ethyl lactate. Examples of suitable blocking agents include alcohol-based blocking agents; oxime-based blocking agents such as formaldehyde oxime, acetaldoxime, acetoxime, methyl ethyl ketoxime, diacetyl monooxime, and cyclohexane oxime; mercaptan-based blocking agents such as butyl mercaptan, hexyl mercaptan, t-butyl mercaptan, thiophenol, methylthiophenol, and ethylthiophenol; acid amide-based blocking agents such as acetic acid amide and benzamide; imide-based blocking agents such as succinimide and maleimide; amine-based blocking agents such as xylidine, aniline, butylamine, and dibutylamine; imidazole-based blocking agents such as imidazole and 2-ethylimidazole; imine-based blocking agents such as methyleneimine and propyleneimine; and pyrazole-based blocking agents such as dimethylpyrazole.

[0081] The blocked isocyanate compound may be a commercially available product, and examples thereof include Duranate TPA-B80E, 17B-60PX, and E402-B80T (all manufactured by Asahi Kasei Corporation), and Trixene BI7982: blocked isocyanate (hexamethylene isocyanate (HDM) trimer, blocking agent: dimethylpyrazole (DMP), manufactured by Baxenden Chemicals).

[0082] The latent thermosetting component may be a reaction product obtained by reacting an amine compound such as imidazole or dicyandiamide with a hydroxyl group-containing compound, a cyclic ether group-containing compound, a carboxyl group-containing compound, or the like.

[0083] The blending amount of the (E) thermosetting component is preferably from 1 to 30 parts by mass, more preferably from 3 to 15 parts by mass, per 100 parts by mass of the curable composition of the present invention. By blending the (E) thermosetting component in an amount of from 1 to 30 parts by mass per 100 parts by mass of the curable composition of the present invention, the storage stability of the curable composition of the present invention can be maintained while further improving the functionality of the cured film, such as heat resistance and plating resistance.

[0084] [(F) Flame retardant] The curable composition of the present invention may contain a known and commonly used flame retardant (F) for the purpose of improving the flame retardancy of the resulting cured product. In addition, the inclusion of a flame retardant can further improve the warpage reduction property after exposure. Examples of (F) flame retardants include phosphorus-based flame retardants such as phosphate esters and condensed phosphate esters, phosphorus-containing compounds having a phenolic hydroxyl group, phosphazene compounds, and metal phosphinates, antimony compounds such as antimony trioxide and antimony pentoxide, halogen compounds such as pentabromodiphenyl ether and octabromodiphenyl ether, metal hydroxides such as aluminum hydroxide and magnesium hydroxide, and layered double hydroxides such as hydrotalcite. Phosphorus-based flame retardants are preferred in terms of their environmental impact and flame retardant effect. Examples of the metal phosphinate include those represented by the following structural formula (2): [ka] (In formula (2), R 1 , R 2 each represents an alkyl group having 1 to 6 carbon atoms or an aryl group having 12 or less carbon atoms, M represents calcium, aluminum, or zinc, and when M represents aluminum, m=3, and when M represents any other metal, m=2. Preferably, the compound has a structure represented by the following formula:

[0085] More preferred are compounds having a structure in which M in formula (2) represents aluminum.

[0086] By using a metal phosphinate, the flame retardancy of the cured film can be improved without impairing the flexibility of the film.

[0087] Specific examples of the phosphinic acid constituting the metal phosphinate include phosphinic acid, dimethylphosphinic acid, ethylmethylphosphinic acid, diethylphosphinic acid, methyl-n-propylphosphinic acid, methanedi(methylphosphinic acid), benzene-1,4-(dimethylphosphinic acid), methylphenylphosphinic acid, phenylphosphinic acid, diphenylphosphinic acid, and mixtures thereof.

[0088] Commercially available products include, for example, Exolit OP 1240, 1240, 1312, 1400, 930, 945TP, and OP-935.

[0089] From the viewpoint of low warpage and flexibility after exposure, it is preferable to use a phosphazene compound as a phosphorus-based flame retardant. The phosphazene compound is preferably a phenoxyphosphazene having a phosphazene structure and a phenoxy group substituted with one of a cyano group (-CN), a hydroxyl group (-OH), and a methyl group. In particular, it is preferable that the basic skeleton has a hexaphenoxycyclotriphosphazene structure, and at least two of the six phenoxy groups in the structure are substituted with a cyano group (-CN) or a hydroxyl group (-OH).

[0090] A preferred embodiment is a structure in which only one of the two phenoxy groups bonded to the phosphorus atom in the hexaphenoxycyclotriphosphazene structure is substituted with one cyano group (-CN), and the hexaphenoxycyclotriphosphazene structure as a whole has two such substituted phenoxy groups.

[0091] Another preferred embodiment is a structure in which each of the two phenoxy groups bonded to the phosphorus atom in the hexaphenoxycyclotriphosphazene structure is substituted with a cyano group (-CN), and the entire hexaphenoxycyclotriphosphazene structure has six phenoxy groups substituted in this way.

[0092] Another preferred embodiment is a structure in which only one of the two phenoxy groups bonded to the phosphorus atom in the hexaphenoxycyclotriphosphazene structure is substituted with one hydroxyl group (—OH), and the hexaphenoxycyclotriphosphazene structure as a whole has three such substituted phenoxy groups.

[0093] More preferably, the cyclic phosphazene compound has the following structure: [ka] or [ka] or [ka] The structure has one of the following structures:

[0094] Preferred commercially available phosphazene compounds include, for example, FP-300B, FP-300, and SPH-100 (all manufactured by Fushimi Pharmaceutical Co., Ltd.).

[0095] The (F) flame retardant may be used alone or in combination of two or more kinds.

[0096] The blending amount of the flame retardant (F) in the curable composition of the present invention is, for example, 5% by mass to 60% by mass, and preferably 10% by mass to 50% by mass. When the flame retardant (F) is a phosphorus-based flame retardant, if the blending amount of the phosphorus-based flame retardant is 0.1% by mass to 10% by mass, in terms of the phosphorus content in the curable composition of the present invention, flame retardancy can be effectively imparted while maintaining heat resistance and low warpage.

[0097] [Thermal curing catalyst selected from the group consisting of melamine and its derivatives] The curable composition of the present invention preferably contains a thermosetting catalyst selected from the group consisting of melamine and its derivatives. Melamine and its derivatives act as a curing accelerator for the thermosetting reaction and are used to further improve the adhesion of the cured product to the conductor circuit as well as properties such as heat resistance.

[0098] Examples of the heat curing catalyst selected from the group consisting of melamine and its derivatives include guanamines such as acetoguanamine and benzoguanamine; melamine; and triazine derivatives such as ethyldiamino-S-triazine, 2,4-diamino-S-triazine, and 2,4-diamino-6-xylyl-S-triazine, among which melamine is preferred.

[0099] The thermosetting catalyst selected from the group consisting of melamine and its derivatives can be used alone or in combination of two or more. When a thermosetting catalyst selected from the group consisting of melamine and its derivatives is blended in the curable composition of the present invention, the blending amount thereof is preferably 0.1% by mass or more and 20% by mass or less, more preferably 0.5% by mass or more and 20% by mass or less, and particularly preferably 1% by mass or more and 15% by mass or less, based on 100% by mass of the total amount of the (E) thermosetting component.

[0100] By setting the blending amount of the thermosetting catalyst selected from the group consisting of melamine and its derivatives to 0.1% by mass or more and 20% by mass or less, relative to 100% by mass of the total amount of the (E) thermosetting component, it is possible to improve the storage stability of the curable composition and achieve good thermosetting.

[0101] The curable composition of the present invention may contain additives such as antioxidants, antifoaming / leveling agents, thixotropy-imparting agents / thickeners, coupling agents, dispersants, polymerization retarders, and colorants, as needed.

[0102] Furthermore, the curable composition of the present invention may contain a solvent to adjust the viscosity, but the amount added is preferably small to prevent a decrease in film thickness after curing.Moreover, it is more preferable that the curable composition does not contain a solvent for adjusting the viscosity.

[0103] The curable composition of the present invention is preferably applied to printing by the inkjet method. In order to be applicable to printing by the inkjet method, it is preferable that the composition has a viscosity that allows it to be sprayed by an inkjet printer.

[0104] The viscosity of the curable composition of the present invention is preferably 50 mPa·s or less at 50°C, more preferably 20 mPa·s or less at 50°C, and particularly preferably 15 mPa·s or less at 50°C.

[0105] Therefore, the curable composition of the present invention can be used to directly print a pattern on a substrate for a printed wiring board or the like by inkjet printing.

[0106] Furthermore, the curable composition of the present invention does not undergo a polymerization reaction at room temperature, and therefore can be stably stored as a one-component curable composition.

[0107] The curable composition of the present invention has a low viscosity and can be supplied as an ink to an inkjet printer, and can be used for printing on a substrate. Furthermore, when printed on a thin-film substrate such as a polyimide substrate, the curable composition can suppress warping of the thin-film substrate after exposure, making the composition suitable for use as a solder resist for flexible wiring boards.

[0108] <Cured product obtained from curable composition> The cured product obtained from the curable composition of the present invention can be obtained by, for example, applying 50 mJ / cm 2 to the composition layer immediately after printing. 2 ~1000mJ / cm 2 The curable composition can be obtained by photocuring the composition layer by irradiating it with active energy rays such as ultraviolet rays, electron beams, and actinic rays, preferably ultraviolet rays.

[0109] UV irradiation in an inkjet printer can be performed by attaching a light source such as a high-pressure mercury lamp, metal halide lamp, or UV LED to the side of the print head and scanning by moving the print head or substrate. In this case, printing and UV irradiation can be performed almost simultaneously.

[0110] The photocured product is then thermally cured using known heating means, such as a heating furnace, such as a hot air furnace, an electric furnace, or an infrared induction heating furnace. The heating conditions are preferably 130°C to 170°C for 5 to 90 minutes.

[0111] The cured product obtained from the curable composition of the present invention has excellent flexibility and is therefore particularly suitable as a solder resist for flexible wiring boards.

[0112] Examples of substrates for flexible wiring boards include films made of glass polyimide, polyimide, polyethylene terephthalate, liquid crystal polymer, polycarbonate, and the like.

[0113] <Electronic component having a cured product of the curable composition> When a cured film made of a curable composition pattern-printed on a substrate is used as a solder resist, it is heated in a soldering process for mounting components. Soldering may be performed by any of manual soldering, flow soldering, reflow soldering, etc. For example, in the case of reflow soldering, the solder is preheated at 100°C to 140°C for 1 to 4 hours, and then heated at 240°C to 280°C for about 5 to 20 seconds, which is repeated multiple times (e.g., 2 to 4 times) to heat and melt the solder. After cooling, an electronic component is completed, with components mounted as necessary.

[0114] In the present invention, the term "electronic component" refers to a component used in an electronic circuit, and includes active components such as printed wiring boards, transistors, light-emitting diodes, and laser diodes, as well as passive components such as resistors, capacitors, inductors, and connectors. The cured product of the curable composition of the present invention serves as an insulating cured film for these components, thereby exerting the effects of the present invention.

[0115] The curable composition of the present invention has low viscosity, excellent applicability, and little warping after photocuring. Furthermore, it remains flexible after curing and has excellent adhesion to substrates, flame retardancy, solder heat resistance, plating resistance, and solvent resistance, making it applicable to a variety of uses, with no particular limitations on the applications. For example, it can be used to prepare etching resists, solder resists, and marking inks for printed wiring boards by inkjet printing. In particular, it can be suitably used as a composition for forming solder resists on flexible wiring boards by inkjet printing, which require low warping after exposure and flame retardancy.

[0116] It can also be used as a material for UV molding products, photolithography, and 3D inkjet printing.

[0117] The present invention is not limited to the configurations and examples of the above-described embodiments, and various modifications are possible within the scope of the gist of the invention. [Example]

[0118] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. In the following, unless otherwise specified, "parts" refers to parts by mass.

[0119] <1. Preparation of Curable Compositions of Examples 1 to 18 and Comparative Examples 1 to 4> The components were mixed in the proportions (unit: parts by mass) shown in Table 1 below and stirred with a dissolver. Then, dispersion was carried out for 2 hours using 1 mm zirconia beads in a bead mill to obtain curable compositions of the present invention (Examples 1 to 18) and comparative examples (Comparative Examples 1 to 4).

[0120] [Table 1]

[0121] *1: α-(allyloxymethyl)methyl acrylate (AOMA: manufactured by Nippon Shokubai Co., Ltd.) *2: Difunctional urethane acrylate, viscosity at 25°C: 2,000 mPa·s, Mw=1,000 (UA-2000, manufactured by Shin-Nakamura Chemical Co., Ltd.) *3: Difunctional urethane acrylate, viscosity at 25°C: 12,500 mPa·s, Mw=1,000 (Ebecryl 8402, manufactured by Daicel Allnex Corporation) *4: Difunctional urethane acrylate, viscosity at 25°C: 25,000 mPa·s, Mw=6,500 (UN-6200, manufactured by Negami Chemical Industries, Ltd.) *5: Trifunctional urethane acrylate, viscosity at 25°C: 15,000 mPa·s (UA-7100, manufactured by Shin-Nakamura Chemical Co., Ltd.) *6: Hexafunctional urethane acrylate oligomer, viscosity at 25°C: 1,000-3,000 mPa·s (DM576, manufactured by Double Bond Chemical Co., Ltd.) *7: Trimethylolpropane triacrylate (A-TMPT, manufactured by Shin-Nakamura Chemical Co., Ltd.) *8: 1,9-nonanediol diacrylate (1,9-NDA, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) *9: Dipropylene glycol diacrylate (DPGDA, manufactured by Daicel Allnex Co., Ltd.) *10: Ethoxylated bisphenol A diacrylate (A-BPE-10, manufactured by Shin-Nakamura Chemical Co., Ltd.) *11: 4-hydroxybutyl acrylate (4HBA, manufactured by Nippon Kasei Co., Ltd.) *12: Trifunctional blocked isocyanate (BI7982, manufactured by Baxenden Chemical) *13: Melamine (Nissan Chemical Co., Ltd.) *14: 2-(Dimethylamino)-2-[(4-methylphenyl)methyl]-1-[4-(4-morpholinyl)phenyl]-1-butanone (Omnirad 379, manufactured by IGM) *15: Phosphazene compound (phosphorus content 12.5%) (FP-300B, manufactured by Fushimi Pharmaceutical Co., Ltd.) *16: Metal phosphinate (phosphorus content 23.0%) (OP935, manufactured by Clariant Chemicals Co., Ltd.) *17: Aluminum hydroxide (H42M, manufactured by Showa Denko) *18: Phthalocyanine blue colorant (Pigment Blue 15:3) *19: Anthraquinone yellow colorant (Pigment Yellow 147)

[0122] <2. Evaluation> The viscosity of the curable compositions of Examples 1 to 18 and Comparative Examples 1 to 4 was evaluated as follows. Test samples were prepared as described below, and evaluations were performed on the coatability, post-exposure warpage, flexibility (MIT test), solder heat resistance, solvent resistance, electroless gold plating resistance, and flame retardancy. The results are shown in Table 2.

[0123] (1) Viscosity The viscosity of the curable compositions of Examples 1 to 18 and Comparative Examples 1 to 4 was measured at an ink temperature of 50° C. and 100 rpm using a cone-plate viscometer (TVH-33H manufactured by Toki Sangyo Co., Ltd.) and evaluated according to the following criteria.

[0124] ◎: 10mPa·s or less ○: More than 10mPa·s but less than 20mPa·s ×: More than 20mPa·s

[0125] (2) Conditions for forming the cured film The curable compositions of Examples 1 to 18 and Comparative Examples 1 to 4 were applied using an inkjet printing device CPS6151 (manufactured by Microcraft). The array used was a KM1024iSHE (manufactured by Microcraft, droplet volume 6 pL, number of nozzles 2 x 1024, head temperature 50°C). Photocuring was performed using an SGHUV-UN-L042-B (manufactured by Microcraft, LED light source, wavelength 365 nm) as the light source, at 300 mJ / cm. 2 Then, a hot air circulation drying oven DF610 (manufactured by Yamato Scientific Co., Ltd.) was used as the heating device, and the coating was fully cured at 150°C for 60 minutes.

[0126] (3) Spreadability The curable compositions of Examples 1 to 18 and Comparative Examples 1 to 4 were applied to a copper surface of sulfuric acid-treated ESPANEX (registered trademark) M (Nippon Steel Chemical & Material Co., Ltd.) to a coating thickness of 20 μm using an inkjet printing device CPS6151 (Microcraft Co., Ltd.). The coating surface was visually observed and evaluated according to the following criteria.

[0127] ○: The coating is even and the surface is smooth. △: The entire surface is coated, but streaks occur in the direction of the head movement. ×: Part of the coating is missing

[0128] (4) Warpage after exposure The curable compositions of Examples 1 to 18 and Comparative Examples 1 to 4 were photocured using an inkjet printer CPS6151 (manufactured by Microcraft Co., Ltd.) under a photocuring condition of 800 mJ / cm 2The resulting solution was applied to one side of sulfuric acid-treated Kapton (registered trademark) 200H or 100H (manufactured by DuPont-Toray Co., Ltd.). The resulting laminate of exposed coating films was cut into 5 cm x 5 cm (length x width) samples (film thickness: 15 μm). Each sample was left standing on a horizontal workbench for 30 minutes with the exposed coating film side facing up, and the height of each of the four edges of the sample raised from the workbench was measured with a ruler to determine the average height of the four edges. The same test was performed three times for each sample, and the average of the three tests was calculated and evaluated according to the following criteria.

[0129] ◎: The average total height of the four edges is 5 mm or less ○: The average total height of the four edges is more than 5 mm and less than 10 mm ×: The average total height of the four edges is 10 mm or more

[0130] (5) Flexibility (MIT Test) The curable compositions of Examples 1 to 18 and Comparative Examples 1 to 4 were applied to a 25 μm polyimide substrate with a 12 μm thick copper circuit pattern that had been sulfuric acid-treated using a CP56151 manufactured by Microcraft Co., Ltd. Then, a 20 μm thick cured film was formed according to the above "(2) Conditions for forming the cured film." The resulting cured film was subjected to the MIT test (R=0.38 mm) based on JIS P8115 to evaluate its flexibility.

[0131] Specifically, as shown in Figure 1, test piece 1 was mounted on the device, and with a load F (0.5 kgf) applied, test piece 1 was attached vertically to clamp 2, and bent at a bending angle α of 135 degrees and a bending speed of 175 cpm, and the number of times it was bent back and forth until it broke was measured. The test environment was 25°C, and the radius of curvature was R = 0.38 mm. The evaluation criteria were as follows:

[0132] ◎: 200 times or more ○: 150-199 times △: 101~149 times ×: 100 times or less

[0133] (6) Solder heat resistance The curable compositions of Examples 1 to 18 and Comparative Examples 1 to 4 were printed on an inkjet printer CPS6151 (manufactured by Microcraft) under photocuring conditions of 800 mJ / cm 2 The test substrate was coated with a 12 μm thick copper paste and a 50 μm thick polyimide circuit pattern substrate that had been treated with sulfuric acid. A 20 μm thick cured film was then formed according to the above "(2) Conditions for forming the cured film." A rosin-based flux was applied to the resulting evaluation substrate, which was then immersed once or twice in a solder bath pre-set to 260°C for 5 seconds. The flux was then washed off with denatured alcohol, and a cross-cut tape peel test was performed to evaluate swelling and peeling of the cured film. The evaluation criteria were as follows:

[0134] ⊚: After immersion for 5 seconds twice, no peeling of the cured film was observed even when a peel test was carried out using Cellotape (registered trademark). ○: After immersion for 5 seconds once and a peel test using Cellotape (registered trademark), no peeling of the cured film was observed, but after immersion for 5 seconds twice, swelling and peeling of the cured film were observed. ×: After immersion for 5 seconds once, the cured film swelled and peeled.

[0135] (7) Solvent resistance The curable compositions of Examples 1 to 18 and Comparative Examples 1 to 4 were printed on an inkjet printer CPS6151 (manufactured by Microcraft) under photocuring conditions of 800 mJ / cm 2 The coating was applied to the copper surface of sulfuric acid-treated ESPANEX (registered trademark) M (manufactured by Nippon Steel Chemical & Material Co., Ltd.) using the same and heated in a hot air circulation drying oven at 150°C for 60 minutes to obtain a cured film with a thickness of 20 μm. The cured film was then immersed in propylene glycol monomethyl acetate for 30 minutes, after which the coating condition was evaluated. The evaluation criteria are as follows:

[0136] ○: No change was observed △: Only slight changes ×: Significant changes

[0137] (8) Electroless gold plating resistance The curable compositions of Examples 1 to 18 and Comparative Examples 1 to 4 were applied to a circuit pattern substrate with a copper thickness of 12 μm and a polyimide thickness of 50 μm that had been treated with sulfuric acid using an inkjet printing device CPS6151 (manufactured by Microcraft Co., Ltd.). Then, a cured film with a thickness of 20 μm was formed according to the above-mentioned "(2) Conditions for forming the cured film." The obtained evaluation substrate was gold-plated using a commercially available electroless nickel plating bath and electroless gold plating bath under conditions of nickel 5 μm and gold 0.03 μm, and the surface condition of the cured film was observed. The evaluation criteria were as follows:

[0138] ○: No change was observed ×: Significant whitening or cloudiness occurred

[0139] (9) Flame retardancy The curable compositions of Examples 1 to 18 and Comparative Examples 1 to 4 were applied to both sides of Kapton 100H (manufactured by DuPont-Toray Co., Ltd.) using an inkjet printing device CPS6151 (manufactured by Microcraft Co., Ltd.). Then, cured films were formed according to the above "(2) Conditions for forming cured films" (the coating thickness on each side was 20 μm). The resulting cured films were subjected to a thin material vertical combustion test in accordance with the UL94 standard. The evaluation criteria were as follows:

[0140] ◎: Passed VTM-0 and the burning time of each sample was less than 7 seconds ○: Passed VTM-0, and the burning time of each sample was between 7 and 10 seconds Not: VTM-0 failed

[0141] [Table 2]

[0142] As shown in Table 2, in Examples 1 to 18 according to the present invention, the curable compositions had low viscosity, and even after being applied to a thin film substrate, particularly a particularly thin substrate such as Kapton 100H, and exposed to light, the warping of the substrate was kept low, and at the same time, the coating film after curing had excellent flexibility and solder heat resistance.

[0143] Furthermore, a comparison of Examples 1 to 3 and 15 with Examples 16 to 18 shows that the inclusion of the flame retardant (F) not only imparts flame retardancy to the cured coating film, but also further improves warpage reduction after exposure.A comparison of Example 14 with Example 15 shows that the use of a phosphorus-based flame retardant (F) further improves the heat resistance of the cured coating film. Although Examples 16 to 18 failed the flame retardancy test (rated as Not passed), this was due to the absence of a flame retardant, and does not negate the effects of the present invention.

[0144] Furthermore, a comparison between Example 2 and Example 8 shows that when the flame retardant (F) was phenoxyphosphazene, not only the flame retardancy but also the viscosity and post-exposure warpage properties of the curable composition could be improved.

[0145] Furthermore, a comparison between Example 2 and Example 9 revealed that when the ratio of (A) / (B) was greater than 175% by mass, the viscosity of the curable composition, post-exposure warpage, and flexibility of the cured film were further improved.

[0146] Furthermore, a comparison between Example 2 and Example 10 revealed that when the ratio of (A) / (F) was greater than 49 mass %, the viscosity of the curable composition, post-exposure warpage, and solder heat resistance of the cured film were further improved.

[0147] Furthermore, a comparison between Example 2 and Example 11 revealed that the flame retardancy and solder heat resistance of the cured film were improved when the composition further contained a compound having a (C4) aromatic ring and two or more (meth)acryloyl groups, and a comparison between Example 2 and Example 12 revealed that the solder heat resistance of the cured film was improved when the composition further contained a photocurable compound having no (C3) aromatic ring and three or more (meth)acryloyl groups.

Claims

1. (A) Formula (1) 【Chemistry 1】 (In formula (1), R １ represents a hydrocarbon group having 1 to 4 carbon atoms, which may be linear, branched, or cyclic and may contain an ether bond (however, the hydrocarbon group may have a substituent). a radical polymerizable monomer represented by the formula: (B) a photocurable urethane compound having two (meth)acryloyl groups; (C) a compound having a (meth)acryloyl group other than (A) and (B); (D) a photopolymerization initiator; (E) a thermosetting component; and Contains The (E) thermosetting component contains a latent thermosetting component. A curable composition characterized by:

2. The curable composition according to claim 1, further comprising (F) a flame retardant.

3. 3. The curable composition according to claim 2, wherein the blending amount of the photocurable urethane compound (B) having two (meth)acryloyl groups relative to the flame retardant (F) is 1% by mass or more and 70% by mass or less.

4. The curable composition according to any one of claims 1 to 3, characterized in that a blending ratio of the radical polymerizable monomer (A) represented by formula (1) to the photocurable urethane compound (B) having two (meth)acryloyl groups is 250 mass% or more and 10,000 mass% or less.

5. The curable composition according to any one of claims 2 to 4, characterized in that a mixing ratio of the radical polymerizable monomer (A) represented by formula (1) relative to the flame retardant (F) is 50 mass% or more and 350 mass% or less.

6. 2. The curable composition according to claim 1, wherein the latent thermosetting component is a blocked isocyanate compound.

7. The curable composition according to any one of claims 2 to 6, wherein the flame retardant (F) is a phosphorus-based flame retardant.

8. The curable composition according to claim 7, wherein the phosphorus-based flame retardant is a phenoxyphosphazene.

9. 9. The curable composition according to claim 1, wherein the viscosity at 50° C. is 50 mPa·s or less.

10. A cured product obtained from the curable composition according to any one of claims 1 to 9.

11. An electronic component comprising the cured product according to claim 10.

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