Active energy ray-curable inkjet ink and inkjet recording method

Abstract

The present disclosure relates to an active energy ray-curable inkjet ink and an inkjet recording method. The present disclosure aims to provide an active energy ray-curable inkjet ink and an inkjet recording method which can reliably suppress elution of a dye into a chemical liquid such as an etching solution, an alkali stripping solution, and the like, have excellent etching resistance and stripping properties using an alkali stripping solution (alkali stripping properties), and have good seal release properties. The active energy ray-curable inkjet ink contains a dye having an amino group; an acrylic acid; an acrylic acid polymerizable compound (A) in which n represents 1 in the following general formula (1); and an acrylic acid polymerizable compound (B) in which n represents 2 in the following general formula (1).[Chem. 1]

Description

Technical Field

[0001] This disclosure relates to active energy ray curable inkjet inks and inkjet recording methods. Background Technology

[0002] Previously, photolithography and screen printing were used to form the resist layer, solder resist layer and markings on printed circuit boards.

[0003] On the other hand, as a method for manufacturing a printed circuit board using an inkjet printer, a conductor circuit pattern is drawn on a copper-clad laminate of a printed wiring board using an inkjet printer. It is known that a resist layer is formed therefrom, followed by etching.

[0004] In such etching processes, dyes sometimes dissolve in etching solutions, alkaline stripping solutions, and other chemicals. Consequently, the dissolved dyes may re-adhere to the substrate, or the etching effect and stripping properties of the etching solutions and alkaline stripping solutions may be reduced, leading to problems with the reuse of these chemicals.

[0005] Patent Document 1 discloses an ink containing a dye having an anthraquinone backbone and an amino group, a monomer having a carboxyl group, and a photopolymerization initiator. Using this ink, decolorization during photocuring can be suppressed by allowing the amine site of the dye to interact with the carboxyl-containing monomer.

[0006] However, simply using the interaction between the amine site of the dye and the monomer containing the carboxyl group, a simple acid-base interaction, is insufficient to adequately suppress the dissolution of the dye into etching solutions, alkaline stripping solutions, and other chemical solutions.

[0007] Existing technical documents

[0008] Patent documents

[0009] Patent Document 1: Japanese Patent Application Publication No. 2016-102138 Summary of the Invention

[0010] The problem that the invention aims to solve

[0011] This disclosure was made in view of the above-mentioned problems and conditions. The problem solved by this disclosure is to provide an active energy ray curable inkjet ink and inkjet recording method that can reliably suppress the dissolution of dye into etching solutions, alkaline stripping solutions, and other solutions, and has excellent etching resistance and stripping properties (alkaline stripping properties) when using an alkaline stripping solution.

[0012] means for solving problems

[0013] To address the aforementioned issues, the causes were investigated, and it was found that the dissolution of the dye into the solution could be reliably suppressed by using dyes containing amino groups, acrylic acid, specific acrylic polymeric compounds (A) and (B). Furthermore, excellent etching resistance and peelability using alkaline stripping solutions were also observed.

[0014] That is, the following methods are used to solve the above problems.

[0015] The active energy ray curable inkjet ink disclosed herein contains:

[0016] Dyes containing amino groups;

[0017] acrylic acid;

[0018] In the following general formula (1), n ​​represents 1 acrylic polymer (A); and

[0019] In the following general formula (1), n ​​represents 2 acrylic polymeric compounds (B).

[0020] [Chemistry 1]

[0021]

[0022] The effects of the invention

[0023] According to the above-described means of this disclosure, it is possible to provide an active energy ray curable inkjet ink and an inkjet recording method that can reliably suppress the leaching of dye into etching solutions, alkaline stripping solutions, and other solutions, exhibit excellent etching resistance and stripping properties when using alkaline stripping solutions.

[0024] While the mechanism of action or manifestation of the effects of this disclosure is not yet clear, the following speculations are made.

[0025] The active energy X-ray curable inkjet ink of this disclosure uses acrylic acid, an acrylic polymeric compound (A) of formula (1) with n=1, and an acrylic polymeric compound (B) of formula (1) with n=2. Therefore, acrylic acid, the acrylic polymeric compound (A), and the acrylic polymeric compound (B), which have different polymeric sites and lengths to the carboxyl group, interact with the amine sites of the dye. As a result, acrylic acid, the acrylic polymeric compound (A), and the acrylic polymeric compound (B) are firmly bonded to the dye. Therefore, the dissolution of the dye into etching solutions, alkaline stripping solutions, and other similar solutions can be reliably suppressed.

[0026] In terms of this effect, etching resistance is improved because multiple ionic interactions centered on the dye are generated simultaneously in the resist film.

[0027] Furthermore, during immersion in the alkaline stripping solution, the tightly bonded portion of the resist film to the substrate is easily peeled off. That is, compared to the covalent crosslinking typically used with multifunctional monomers, the ionic interactions are more flexible, allowing for effective swelling and thus enabling the stripping of the resist film. As the mechanism described above suggests, regarding the dye itself, due to various interactions, the dissolution of the dye into the etching solution and the alkaline stripping solution is suppressed. Additionally, both etching resistance and the peelability achieved using the alkaline stripping solution can be balanced during etching and stripping processes. Attached Figure Description

[0028] Figure 1 This diagram illustrates the manufacturing process of a printed circuit board in which the ink of this disclosure is used to form a resist layer.

[0029] Figure 2 This diagram illustrates the manufacturing process of a printed circuit board in which the ink of this disclosure is used to form a resist layer.

[0030] Figure 3 This diagram illustrates the manufacturing process of a printed circuit board in which the ink of this disclosure is used to form a resist layer.

[0031] Figure 4 This diagram illustrates the manufacturing process of a printed circuit board in which the ink of this disclosure is used to form a resist layer.

[0032] Figure 5 This diagram illustrates the manufacturing process of a printed circuit board in which the ink of this disclosure is used to form a resist layer.

[0033] Figure 6 This diagram illustrates the manufacturing process of a printed circuit board in which the ink of this disclosure is used to form a resist layer.

[0034] Figure 7 This diagram illustrates the manufacturing process of a printed circuit board in which the ink of this disclosure is used to form a resist layer.

[0035] Figure 8 This diagram illustrates the manufacturing process of a printed circuit board in which the ink of this disclosure is used to form a resist layer. Detailed Implementation

[0036] The active energy ray curable inkjet ink disclosed herein comprises: an amino-containing dye; acrylic acid; an acrylic polymeric compound (A) in which n represents 1 in the following general formula (1); and an acrylic polymeric compound (B) in which n represents 2 in the following general formula (1).

[0037] [Chemistry 2]

[0038]

[0039] This feature is a common or corresponding technical feature in the following embodiments.

[0040] As an embodiment of this disclosure, it is preferable to include an acrylic polymeric compound (C) in which n represents 3 in the general formula (1), and the content of the acrylic polymeric compound (C) is 0.1% by mass or more. Thereby, the acrylic polymeric compound (C) interacts with the amine sites of the dye, thereby further suppressing the dissolution of the dye into the solution. Furthermore, excellent etch resistance and alkali stripping properties are also observed.

[0041] In addition, from the perspectives of dye dissolution inhibition, etching resistance and alkali stripping properties, monomers containing acrylamide groups are preferred.

[0042] As a photopolymerization initiator, from the perspective of dye dissolution inhibition and alkali stripping properties, a polymerization initiator containing an acylphosphine structure is preferred.

[0043] From the perspective of etching resistance and alkali stripping properties, it is preferable to contain a multifunctional monomer, wherein the content of the multifunctional monomer is less than 30% by mass.

[0044] From the perspective of etching resistance, polymeric monomers containing alicyclic structures are preferred.

[0045] From the perspective of excellent dye dissolution inhibition, alkali stripping and sealing properties, the acrylic acid content is preferably 15% by mass or less.

[0046] From the perspective of excellent ejection performance using inkjet technology, a viscosity of 8 to 15 mPa·s is preferred within the range of 40 to 90°C.

[0047] From the perspective of dye dissolution inhibition and etching resistance, the dye is preferably a salt of a compound having a triarylmethane structure, and the molecular weight of the counter anion is 100 or more.

[0048] From the perspectives of dye dissolution inhibition, etching resistance, and alkali stripping resistance, the presence of a gelling agent is preferred. Furthermore, by using a gelling agent, ink droplets adhering to the recording medium can be immobilized (pinned), and by inhibiting droplet coalescence, high-resolution images can be formed.

[0049] The active energy ray curable inkjet ink disclosed herein is suitable for use with resists or for coating resists.

[0050] The inkjet recording method disclosed herein involves ejecting an active energy ray curable inkjet ink onto a substrate and curing it using active light. The active energy ray curable inkjet ink disclosed herein is used as the active energy ray curable inkjet ink. This reliably suppresses the leaching of dye into etching solutions, alkaline stripping solutions, and other chemicals, and provides good etching resistance and alkaline stripping properties.

[0051] The following describes this disclosure, its constituent elements, and the methods and schemes for implementing this disclosure. It should be noted that in this application, "~" is used to encompass the numerical values ​​described before and after it as lower and upper limits.

[0052] [Active Energy Ray Curable Inkjet Ink]

[0053] The active energy ray curable inkjet ink contains an amino dye, acrylic acid, an acrylic polymeric compound (A) in which n represents 1 in the following general formula (1), and an acrylic polymeric compound (B) in which n represents 2 in the following general formula (1).

[0054] [Chemistry 3]

[0055]

[0056] In this specification, "active energy ray curable inkjet ink" refers to inkjet ink that is cured by irradiation with active energy rays. Hereinafter, "active energy ray curable inkjet ink" will also be abbreviated as "ink".

[0057] "Active energy rays" refer to radiation that exerts physical and chemical effects on polymerization initiators or polymerizable compounds, promoting cross-linking and polymerization reactions. Specifically, active energy rays include visible light, ultraviolet light, X-rays, electron beams, alpha rays, beta rays, and gamma rays.

[0058] A "monofunctional monomer" is a compound having one polymerizable functional group. A "polyfunctional monomer" is a compound having two or more polymerizable functional groups.

[0059] Furthermore, "n-functional" indicates the presence of n polymerizable functional groups. Similarly, "n-functional or more" indicates the presence of more than n polymerizable functional groups. Examples of polymerizable functional groups include acryloyl, methacryl, allyl, vinyl, and vinyl ester groups.

[0060] In addition to dyes, acrylic acid, acrylic polymeric compound (A) and acrylic polymeric compound (B), the ink disclosed herein may, as needed, contain acrylic polymeric compound (C) described later, monomers having acrylamide groups, photopolymerization initiators, multifunctional monomers, polymeric monomers having alicyclic structures, or gelling agents.

[0061] The following is a description of the components of the ink.

[0062] <Dye>

[0063] The ink contains an amino-based dye. In addition to the dye, the ink may also contain pigments. By including a dye in the ink, the ink, colored by the dye, cures to form a cured film, and the resist pattern becomes clear.

[0064] There are no particular limitations on the dye used; for example, it is preferable to contain at least one dye selected from dyes having an amino group and a triarylmethane or anthraquinone skeleton, and dyes having a phthalocyanine skeleton. These dyes are preferred from the perspective of high dye dissolution inhibition effect in the ink-cured film.

[0065] In particular, as a dye, a salt of a compound having a triarylmethane structure is preferred. Moreover, from the perspective of dye dissolution inhibition effect and etching resistance in the ink-cured film, it is more preferable that the counter anion of the salt of a compound having a triarylmethane structure has a molecular weight of 100 or more.

[0066] Examples of compounds having a triarylmethane structure include triphenylmethane, crystal violet, solvent violet 8, basic violet 1, solvent blue 5, and basic blue 7.

[0067] The structural formula of Solvent Blue 5 is shown below.

[0068] [Chemistry 4]

[0069]

[0070] The structural formula of Basic Blue 7 is shown below.

[0071] [Chemistry 5]

[0072]

[0073] Counter anions with a molecular weight of 100 or higher include, for example, hexafluorophosphate ion, trifluoromethanesulfonate ion, bis(trifluoromethanesulfonyl)imide ion, tetraphenylborate ion, Acid Yellow 36, Acid Yellow 42, etc.

[0074] Dyes that are salts of compounds with such a triarylmethane structure include, for example, VALIFAST violet 1701 (manufactured by Orient Chemical Industries Co., Ltd.) and VALIFAST violet 1704 (manufactured by Orient Chemical Industries Co., Ltd.).

[0075] VALIFAST violet1701 is a salt of a triarylmethane structure, with Solvent Violet 8 as its solvate and Acid Yellow 42 as its counter anion.

[0076] Examples of dyes with an anthraquinone skeleton and an amino group include Solvent Red 122 and Solvent Blue 35.

[0077] The structural formula of Solvent Red 122 is shown below.

[0078] [Chemistry 6]

[0079]

[0080] The structural formula of Solvent Blue 35 is shown below.

[0081] [Chemistry 7]

[0082]

[0083] Examples of dyes with a phthalocyanine skeleton include Direct Blue 87.

[0084] The structure of Direct Blue 87 is shown below.

[0085] [Chemistry 8]

[0086]

[0087] The dye content relative to the total ink is preferably in the range of 0.01 to 3% by mass, more preferably 0.03 to 2% by mass, and even more preferably in the range of 0.05 to 1.5% by mass. By setting the dye content within this range, a well-colored cured film can be obtained, and etching resistance is improved.

[0088] As the dye, it can be any dye having an amino group, except for dyes having an anthraquinone skeleton and an amino group, dyes having a naphthalene skeleton and an amino group, dyes having a triarylmethane structure, and dyes having a phthalocyanine skeleton.

[0089] <Acrylic>

[0090] Acrylic acid is a compound in the general formula (1) where n represents 0. Commercially available acrylic acid products include, for example, 98% acrylic acid (manufactured by Toa Synthetic Co., Ltd.), acrylic acid (manufactured by Tokyo Chemical Industry Co., Ltd.), and acrylic acid (manufactured by Fujifilm and Hikari Pure Chemical Co., Ltd.).

[0091] The acrylic acid content relative to the total mass of the ink is preferably 15% by mass or less, more preferably in the range of 3% to 10% by mass.

[0092] <Acrylic Polymer Compound (A)>

[0093] The acrylic polymeric compound (A) is a compound in the general formula (1) where n represents 1. Commercially available examples of acrylic polymeric compounds (A) include, for example, 2-Carboxyethyl acrylate (manufactured by Sigma-Aldrich).

[0094] From the perspective of inhibiting the dissolution of dyes, the content of acrylic polymeric compound (A) relative to the total ink is preferably in the range of 0.5 to 15% by mass, and more preferably in the range of 3 to 10% by mass.

[0095] <Acrylic Polymer Compound (B)>

[0096] The acrylic polymeric compound (B) is a compound in the general formula (1) in which n represents 2.

[0097] From the perspective of inhibiting the dissolution of dyes, the content of acrylic polymeric compound (B) relative to the total ink is preferably in the range of 0.1 to 10% by mass, and more preferably in the range of 1 to 5% by mass.

[0098] From the perspective of inhibiting dye dissolution, the mass ratio of the content (mass %) of acrylic polymeric compound (A) relative to the total ink content to the content (mass %) of acrylic polymeric compound (B) relative to the total ink content (mass %) (acrylic polymeric compound (A) / acrylic polymeric compound (B)) is preferably in the range of 1 to 5.

[0099] <Acrylic Polymer Compound (C)>

[0100] The acrylic polymeric compound (C) is a compound in the general formula (1) in which n represents 3.

[0101] It may not contain acrylic polymeric compounds (C), but it is preferable to contain 0.1% by mass or more, more preferably in the range of 0.5% to 1% by mass, relative to the ink as a whole.

[0102] As a method for preparing acrylic polymeric compounds (B) and (C), for example, the separation of reaction product (D) obtained by the following reaction using high performance liquid chromatography (HPLC) can be cited.

[0103] In a three-necked reactor equipped with a temperature probe and a reflux condenser, 100g of 98% acrylic acid (manufactured by Toa Synthetic Co., Ltd.), 20% of Amberlyst A15 resin, and 1000ppm of hydroquinone methyl ester as a polymerization inhibitor were added. The reaction medium was then stirred at 125°C while being bubbled with air to obtain the reaction product (D).

[0104] The conditions for HPLC are as described in the examples below.

[0105] For acrylic polymeric compound (B), the peak at an elution time of approximately 13.5 minutes was recovered, and for acrylic polymeric compound (C), the peak at an elution time of approximately 15 minutes was recovered.

[0106] <Monomers with acrylamide groups>

[0107] Monomers containing an acrylamide group include, for example, N,N-dimethylacrylamide, N-hydroxyethylacrylamide, acryloylmorpholine, N,N-diethylacrylamide, N-isopropylacrylamide, diacetoneacrylamide, etc.

[0108] Commercially available monomers containing acrylamide groups include, for example, DMAA, HEAA, ACMO, DEAA, NIPAM, DAAM, etc., manufactured by KJ Chemicals.

[0109] It may also be free of monomers containing acrylamide groups, wherein the content of the monomers containing acrylamide groups relative to the total ink is preferably in the range of 0 to 60% by mass, more preferably in the range of 10 to 30% by mass.

[0110] <Alicyclic monomer>

[0111] Polymerizable monomers with an alicyclic structure are also called alicyclic monomers. Alicyclic monomers can be monofunctional monomers (alicyclic monofunctional monomers) or polyfunctional monomers with an alicyclic structure (alicyclic polyfunctional monomers). In the inks disclosed herein, alicyclic monofunctional monomers are preferred. Furthermore, the molecular weight of the alicyclic monofunctional monomer is preferably in the range of 200 to 300. Moreover, the alicyclic monomer is preferably an alicyclic (meth)acrylate monomer. In this specification, "(meth)acrylate" is a general term for "acrylate" and "methacrylate," referring to one or both of them.

[0112] The molecular weight of the alicyclic monofunctional monomer is preferably in the range of 200 to 300. Furthermore, the alicyclic monofunctional monomer is preferably an alicyclic (meth)acrylate monomer. In this specification, "(meth)acrylate" is a general term for "acrylate" and "methacrylate," referring to one or both of them.

[0113] Examples of alicyclic monofunctional monomers include isoborneol acrylate, 3,5,5-trimethylcyclohexyl acrylate, 4-tert-butylcyclohexyl acrylate, dicyclopentenoxyethyl acrylate, dicyclopentenyl acrylate, and dicyclopentyl acrylate.

[0114] Commercially available alicyclic monofunctional monomers include, for example, Miramer M1130 (manufactured by Miwon) (Tg: 43℃), Miramer M1140 (manufactured by Miwon) (Tg: 77℃), Miramer M1150 (manufactured by Miwon) (Tg: 65℃), FA-511AS (manufactured by Resonac) (Tg: 120℃), FA-513AS (manufactured by Resonac) (Tg: 120℃), and FA-512AS (manufactured by Resonac) (Tg: 20℃).

[0115] The content of alicyclic monofunctional monomers relative to the total ink content is preferably in the range of 10 to 60% by mass.

[0116] <Multifunctional Monomer>

[0117] A multifunctional monomer is any monomer having two or more functional groups within its molecule. Preferably, the multifunctional monomer is a difunctional or trifunctional (meth)acrylate monomer. More preferably, the multifunctional monomer is a multifunctional monomer having a cyclic structure.

[0118] Examples of difunctional (meth)acrylate monomers include triethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, dipropylene glycol dimethacrylate, tripropylene glycol dimethacrylate, polypropylene glycol dimethacrylate, 1,4-butanediol dimethacrylate, 1,6-hexanediol dimethacrylate, 1,9-nonanediol dimethacrylate, neopentyl glycol dimethacrylate, dihydroxymethyl-tricyclodecane dimethacrylate, dioxanediol dimethacrylate, bisphenol A PO adduct dimethacrylate, hydroxypentanoic acid neopentyl glycol dimethacrylate, and polytetramethylene glycol dimethacrylate.

[0119] Examples of trifunctional or higher (meth)acrylate monomers include trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, di(trimethylolpropane) tetra(meth)acrylate, glycerol propoxy tri(meth)acrylate, and pentaerythritol ethoxy tetra(meth)acrylate.

[0120] Furthermore, (meth)acrylate monomers can also be modified. Examples of modified compounds include ethylene oxide-modified trimethylolpropane tri(meth)acrylate and ethylene oxide-modified pentaerythritol tetraacrylate. Other examples include caprolactone-modified trimethylolpropane tri(meth)acrylate and other caprolactone-modified (meth)acrylate compounds. Finally, examples include caprolactam-modified dipentaerythritol hexa(meth)acrylate and other caprolactam-modified (meth)acrylate compounds.

[0121] These can be used individually or in combination with two or more.

[0122] Commercially available examples of the aforementioned multifunctional monomers include, for instance, M222 (a difunctional acrylate monomer with a propylene oxide backbone, manufactured by Miwon Corporation), M210 (a difunctional acrylate monomer, neopentyl glycol hydroxypentyl acrylate diacrylate, manufactured by Miwon Corporation), A-DOG (dioxanediol diacrylate, manufactured by Shin-Nakamura Chemical Industry Co., Ltd., molecular weight 326), A-DCP (tricyclodecanediethanol diacrylate, manufactured by Shin-Nakamura Chemical Industry Co., Ltd., molecular weight 304), SR444 (a trifunctional acrylate monomer, manufactured by Alkema Corporation), M262 (tricyclodecanediethanol diacrylate, manufactured by Miwon Corporation), and CD406 (cyclohexanediethanol diacrylate, manufactured by Alkema Corporation). Among these commercially available products, A-DCP, M262, CD406, and A-DOG, which are multifunctional monomers with cyclic structures, are preferred.

[0123] It may also be free of polyfunctional monomers. From the viewpoint of copper high-temperature etching resistance and coating film hardness, the content of the polyfunctional monomers relative to the total ink is preferably 0 to 30% by mass, and more preferably 5 to 20% by mass.

[0124] By using a difunctional monomer with a cyclic structure, the coating becomes tough and has improved etching resistance, making it a preferred choice.

[0125] <Aromatic Monomers>

[0126] Aromatic monomers are monomers containing aromatic rings. Preferably, aromatic monomers have a molecular weight in the range of 200 to 300.

[0127] Examples of aromatic monomers include 2-phenoxyethyl (meth)acrylate, bisphenol A type diacrylate, o-phenylphenoxyethyl (meth)acrylate, and m-phenoxybenzyl (meth)acrylate. Other aromatic monomers include ethoxylated phenoxy (meth)acrylate, alkoxylated phenol (meth)acrylate, and 2-hydroxy-o-phenylphenol propyl (meth)acrylate.

[0128] Commercially available aromatic monomers include, for example, Miramer M1182 (manufactured by Miwon), Miramer M142 (manufactured by Miwon), Miramer M1142 (manufactured by Miwon), SR339NS (manufactured by Sartomer), and V#192HP (manufactured by Osaka Organics).

[0129] The content of aromatic monomers relative to the total ink is preferably in the range of 0 to 40% by mass.

[0130] <Other monomers>

[0131] The ink disclosed herein may also contain other monomers besides those described above.

[0132] Other preferred monomers include, for example, cyclic imide acrylates, caprolactone (meth)acrylates, cyclic trimethylolpropane acetal (meth)acrylates, isooctyl (meth)acrylates, lauryl (meth)acrylates, isodecyl (meth)acrylates, tetrahydrofurfuryl acrylates, stearyl (meth)acrylates, and methoxy polyethylene glycol (meth)acrylates. In particular, monomers having an ethylene glycol site are especially preferred from the viewpoint of reducing curing shrinkage. Furthermore, monomers having a cyclic imide backbone site are preferred from the viewpoint of etch resistance.

[0133] Commercially available examples of the other monomers mentioned above include Aronix M-140 (manufactured by Toa Synthetic Co., Ltd.), Miramer M1088 (manufactured by Miwon Corporation), Miramer M1110 (manufactured by Miwon Corporation), Miramer M150 (manufactured by Miwon Corporation), and SR551 (manufactured by Sartomer Corporation). Compounds having an ethylene oxide moiety are particularly preferred.

[0134] <Polymerization Initiator>

[0135] The polymerization initiator is preferably a free radical polymerization initiator. Examples of free radical polymerization initiators include intramolecular cleavage-type photopolymerization initiators and hydrogen abstraction-type polymerization initiators. In this disclosure, photopolymerization initiators are particularly preferred.

[0136] Regarding photopolymerization initiators, inks may contain only one type or a combination of two or more.

[0137] Examples of intramolecular cleavage-type photopolymerization initiators include acetophenone-based initiators such as 2-hydroxy-2-methyl-1-phenylpropane-1-one, benzyl dimethyl ketal, 4-(2-hydroxyethoxy)phenyl-(2-hydroxy-2-propyl)one, 1-hydroxycyclohexylphenyl ketone, 2-methyl-2-morpholino(4-methylthiophenyl)propane-1-one, and 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butanone; benzoin-based initiators such as benzoin, benzoin methyl ether, and benzoin isopropyl ether; and acylphosphine oxide-based initiators such as 2,4,6-trimethylbenzoin diphenylphosphine oxide and bis(2,4,6-trimethylbenzoin)phenylphosphine oxide.

[0138] Of the above, an initiator based on acylphosphine oxide having an acylphosphine structure is particularly preferred.

[0139] Commercially available examples of intramolecular cleavage-type photopolymerization initiators include OmniRad127, OmniRad184, OmniRad651, OmniRad2959, OmniRad819, OmniRad907, Esacure One (manufactured by IGM Resins), and SPEEDCURE 73 (manufactured by Sartomer).

[0140] Examples of hydrogen-abstracting photopolymerization initiators include benzophenone-based initiators such as methyl benzoyl peroxide, 4-phenylbenzophenone, 4,4'-dichlorobenzophenone, hydroxybenzophenone, 4-benzoyl-4'-methyl-diphenyl sulfide, acrylated benzophenone, 3,3',4,4'-tetra(tert-butylperoxycarbonyl)benzophenone, and 3,3'-dimethyl-4-methoxybenzophenone; and thioxanthone-based initiators such as 2-isopropylthioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, and 2,4-dichlorothioxanthone.

[0141] Examples of commercially available hydrogen-abstracting photopolymerization initiators include SpeedCure 2-ITX, SpeedCure 7010, and SpeedCure BP.

[0142] The content of the polymerization initiator relative to the total ink is preferably in the range of 1 to 10% by mass, and more preferably in the range of 1.5 to 8% by mass.

[0143] <Germizing Agent>

[0144] A gelling agent enables ink droplets adhering to an oxide film to temporarily fix (pinnock) into a gel state. If the ink is pinned in a gel state, ink wetting and spreading are suppressed, and adjacent dots are less likely to merge, thus enabling the formation of a more refined image. Regarding gelling agents, the inks disclosed herein may contain only one type or more than two types.

[0145] Examples of gelling agents include dialkyl ketones, fatty acid esters, fatty acid amides, and oil gelling agents, but the gelling agents used in this disclosure preferably do not have acidic groups such as -OH or -COOH at the end of the alkyl chain. That is, gelling agents without acidic groups are not limited to gelling agents containing only substances without acidic groups with a purity of 100%. Gelation agents without acidic groups also include cases where gelling agents with acidic groups are contained as impurities, provided that the acid value is below 10 mg KOH / g, without hindering the intended effect of the invention.

[0146] As a particularly preferred gelling agent, it comprises at least one compound having a structure represented by the following general formulas (G1) and (G2).

[0147] General formula (G1): R1-CO-R2

[0148] General formula (G2): R3-COO-R4

[0149] [In the formula, R1 to R4 each independently represent a straight-chain portion having 12 or more carbon atoms and may have branches.]

[0150] The ketone wax represented by the above general formula (G1) or the ester wax represented by the above general formula (G2) has 12 or more carbon atoms in its straight-chain or branched hydrocarbon group (alkyl chain). Therefore, the crystallinity of the gelling agent is further improved, and more sufficient space is generated in the following carding structure. As a result, ink media such as solvents and photopolymerizable compounds are easily and sufficiently encapsulated within the aforementioned space, further improving the pinning properties of the ink.

[0151] Furthermore, the number of carbon atoms in the linear or branched hydrocarbon group (alkyl chain) is preferably 26 or less. If the number of carbon atoms is 26 or less, the melting point of the gelling agent is not excessively increased, so there is no need to overheat the ink when spraying it out.

[0152] Based on the above viewpoint, R1 and R2, or R3 and R4, are particularly preferred to be straight-chain hydrocarbon groups with 12 or more but less than 23 carbon atoms.

[0153] Furthermore, from the viewpoint of increasing the gelation temperature of the ink and making the ink gel faster, it is preferable that either R1 or R2, or either R3 or R4, is a saturated hydrocarbon group with 12 or more and 23 or less carbon atoms.

[0154] Based on the above viewpoint, it is more preferable that both R1 and R2, or both R3 and R4, are saturated hydrocarbon groups with 11 or more but less than 23 carbon atoms.

[0155] Examples of ketone waxes represented by the above general formula (G1) include: di(tetracosyl)one (C24-C24), dibenzyl ketone (C22-C22), distearyl ketone (C18-C18), di(eicosyl)one (C20-C20), dipalmityl ketone (C16-C16), dimyristyl ketone (C14-C14), dilauryl ketone (C12-C12), lauryl... Myristyl ketone (C12-C14), lauryl palmityl ketone (C12-C16), myristyl palmityl ketone (C14-C16), myristyl stearyl ketone (C14-C18), myristyl behenyl ketone (C14-C22), palmyl stearyl ketone (C16-C18), palmyl behenyl ketone (C16-C22), stearyl behenyl ketone (C18-C22). It should be noted that the number of carbon atoms in parentheses above represents the number of carbon atoms in each of the two hydrocarbon groups cleaved by the carbonyl group.

[0156] Commercially available examples of ketone waxes represented by the general formula (G1) include: Stearonne (manufactured by Alfa Aeser; stearone) and 18-Pentatriacontanon (manufactured by Alfa Aeser). Other examples of such commercially available products include: Hentriacontan-16-on (manufactured by Alfa Aeser) and KAOWAX T-1 (manufactured by Kao Corporation).

[0157] Examples of fatty acids or ester waxes represented by the general formula (G2) include: behenate (C21-C22), eicosyl eicosanoate (C19-C20), stearate (C17-C18), palmitate stearate (C17-C16), lauryl stearate (C17-C12), cetyl palmitate (C15-C16), and stearate palmitate (C15-C18). Myristyl myristate (C13-C14), cetyl myristate (C13-C16), octyl dodecyl myristate (C13-C20), stearyl oleate (C17-C18), stearyl erucate (C21-C18), stearyl linoleate (C17-C18), behenyl oleate (C18-C22), and eicosyl linoleate (C17-C20). It should be noted that the number of carbon atoms in parentheses above represents the number of carbon atoms in each of the two hydrocarbon groups separated by the ester group.

[0158] Commercially available ester waxes represented by the general formula (G2) include Unistar M-2222SL and SPERMACETI, manufactured by Nippon Yugosuke Corporation (“Unistar” is a registered trademark of the company), EXCEPARL SS, and EXCEPARL MY-M. Additionally, commercially available ester waxes include those manufactured by Kao Corporation (“EXCEPARL” is a registered trademark of the company), EMLEX CC-18, and EMLEX CC-10. Furthermore, examples of commercially available ester waxes include those manufactured by Nihon Emulsion Corporation (“EMALEX” is a registered trademark of the company) and AMREPS PC, manufactured by Advanced Alcohols Industries, Ltd. (“AMREPS” is a registered trademark of the company).

[0159] Most of these commercially available products are mixtures of two or more ingredients, and therefore can be separated, refined, and incorporated into inks as needed. Among these gelling agents, ketone waxes, ester waxes, higher fatty acids, higher alcohols, and fatty acid amides are preferred from the viewpoint of further improving pinning properties.

[0160] The content of the gelling agent relative to the total mass of the ink is preferably in the range of 0.5 to 5.0% by mass. By keeping the content of the gelling agent within this range, excellent etching resistance and plating resistance are achieved, and the gelling agent exhibits good solubility and pinning effect on the solvent components. Furthermore, from the above viewpoint, it is more preferable that the content of the gelling agent in the inkjet ink is in the range of 0.5 to 2.5% by mass.

[0161] Furthermore, from the viewpoint that the gelling agent preferably crystallizes in the ink at a temperature below the gelation temperature of the ink, the gelation temperature is defined as the temperature at which the gelling agent undergoes a phase transition from sol to gel when the ink, which has been solutized or liquefied by heating, is cooled, causing a rapid change in the viscosity of the ink. Specifically, the gelation temperature of the ink is defined as the temperature at which the viscosity of the solutized or liquefied ink increases sharply when cooled while measuring its viscosity using a viscoelasticity measuring device (e.g., MCR300, manufactured by Physica).

[0162] When a gelling agent crystallizes in ink, it sometimes forms a structure in which the ink medium, such as a solvent or photopolymerizable compound, is encapsulated within a three-dimensional space formed by the plate-like crystallized gelling agent. This structure is hereinafter referred to as the "cabin structure".

[0163] When a cardioid structure is formed, the liquid ink medium is contained within the space, making it more difficult for ink droplets to wet and spread, thus further enhancing the pinning properties of the ink. As the pinning properties of the ink increase, ink droplets falling onto the recording medium become less likely to merge, enabling the formation of higher-resolution images.

[0164] To form a gelling structure, it is preferable that the ink medium, such as the solvent and photopolymerizable compounds, in the ink is compatible with the gelling agent. Conversely, when the ink medium, such as the solvent and photopolymerizable compounds, separates from the gelling agent, it is sometimes difficult to form a gelling structure.

[0165] <Other Ingredients>

[0166] The ink disclosed herein may further contain other components, including polymerization inhibitors and surfactants, to achieve the effects of this disclosure. Regarding these components, the ink disclosed herein may contain only one or more of these components.

[0167] (Polymerization inhibitor)

[0168] Examples of polymerization inhibitors include (alkyl)phenol, hydroquinone, catechol, resorcinol, p-methoxyphenol, tert-butylcatechol, tert-butylhydroquinone, pyrogallol, 1,1-picrylhydrazine, phenothiazine, p-benzoquinone, nitrosobenzene, 2,5-di-tert-butyl-p-benzoquinone, dithiobenzoyl disulfide, picric acid, copper ferroin, aluminum N-nitrosophenylhydroxylamine, tri-p-nitrophenylmethyl, N-(3-oxyanilino-1,3-dimethylbutylene)aniline oxide, dibutylcresol, cyclohexanone oxime cresol, guaiacol, o-isopropylphenol, butyraldehyde oxime, methyl ethyl ketone oxime, and cyclohexanone oxime.

[0169] Examples of commercially available polymerization inhibitors include Irgastab UV-10 (manufactured by BASF) and Genorad 18 (manufactured by Rahn A.G.).

[0170] Regarding the amount of polymerization inhibitor, it can be arbitrarily set within the range that achieves the effects of this disclosure. The amount of polymerization inhibitor relative to the total ink can, for example, be set to 0.001% by mass or more but less than 1.0% by mass.

[0171] (surfactant)

[0172] Examples of surfactants include anionic surfactants such as dialkyl sulfosuccinates, alkyl naphthalene sulfonates, and fatty acid salts; nonionic surfactants such as polyoxyethylene alkyl ethers, polyoxyethylene alkyl allyl ethers, acetylacetonate diols, and polyoxyethylene-polyoxypropylene block copolymers; cationic surfactants such as alkylamine salts and quaternary ammonium salts; acryloyl-modified surfactants; and silicone-based and fluorinated surfactants.

[0173] As surfactants based on organosilicon, examples include polyether-modified polysiloxane compounds, specifically Tegorad 2250 (manufactured by Evonik), KF-351A, KF-352A, KF-642 and X-22-4272 (manufactured by Shin-Etsu Chemical Co., Ltd.), BYK 307, BYK 345, BYK 347 and BYK 348 (manufactured by BYK Chemie, Inc. (“BYK” is a registered trademark of the company), and TSF 4452 (manufactured by Momentive Performance Materials Co., Ltd.).

[0174] Fluorinated surfactants are surfactants that replace part or all of the hydrogen atoms bonded to the carbon of hydrophobic groups in conventional surfactants with fluorine.

[0175] Examples of fluorinated surfactants include MegafacF, manufactured by DIC (“Megafac” is a registered trademark of the company), Surflon, manufactured by AGC Seimi Chemical (“Surflon” is a registered trademark of the company), FluoradFC, manufactured by 3M (“Fluorad” is a registered trademark of the company), Monflor, manufactured by Imperial Chemical Industries, Zonyls, manufactured by EI du Pont de Nemours & Co., Licowet VPF, manufactured by Lubeberuke Hekist, and FTERGENT, manufactured by Neos (“FTERGENT” is a registered trademark of the company).

[0176] Acryloyl-modified surfactants include BYK-3500, BYK-3530, BYK-3560 (manufactured by BYKChemie), lauryl acrylate, etc. Acryloyl-modified surfactants are preferred because they can gently adjust the surface tension of inks.

[0177] Regarding the amount of surfactant, it can be arbitrarily set within the range that achieves the effects of this disclosure. The amount of surfactant relative to the total ink can, for example, be set to 0.001% by mass or more but less than 1.0% by mass.

[0178] <Physical properties>

[0179] When the ink disclosed herein contains a gelling agent, it is preferable to have a phase transition point in the range of 40°C or higher but less than 100°C. If the phase transition point is 40°C or higher, the ink gels rapidly after landing on the recording medium, thus further improving pinning properties. Furthermore, if the phase transition point is less than 100°C, the ink's processability becomes better, and its ejection stability is improved.

[0180] From the viewpoint that ink can be ejected at lower temperatures and the load on the image forming apparatus is reduced, the phase transition point of the ink disclosed herein is more preferably in the range of 40 to 60°C.

[0181] The viscosity and phase transition point of the ink disclosed herein at 40–90 °C can be determined by measuring the temperature change of the dynamic viscoelasticity of the ink using a rheometer.

[0182] The viscosity of the ink at 40–90°C is preferably in the range of 8–15 mPa·s. In this disclosure, these viscosity and phase transition point values ​​are obtained by the following method.

[0183] The ink was heated to 100°C, and its viscosity was measured using a Physica MCR301 (manufactured by Anton Paar) at a shear rate of 1000 (1 / s). At the same time, the ink was cooled to 20°C at a shear rate of 11.7 (1 / s) and a cooling rate of 0.1°C / s to obtain the temperature change curve of the viscosity.

[0184] The viscosity at 40–90 °C can be determined by reading the viscosity at each of the 40–90 °C values ​​from the viscosity-temperature curve. The phase transition point can be determined as the temperature at which the viscosity reaches 200 mPa·s on the viscosity-temperature curve.

[0185] The water content (water content) of the ink disclosed herein, as determined by the Karl Fischer method, is preferably 0.02% by mass or more and less than 1.50% by mass relative to the total mass of the ink, more preferably 0.05% by mass or more and less than 1.00% by mass.

[0186] If the moisture content is less than 1.50% by mass, it can prevent the reaction between water and acrylic polymeric compounds that are prone to occur, thereby improving ink preservation and etching resistance.

[0187] By having a water content of 0.02% by mass or more, the swelling property of water in the coating film is improved, thereby improving the peelability of the aqueous stripping solution containing solvent.

[0188] The moisture content can be determined using known methods such as the Karl Fischer method.

[0189] The Karl Fischer method for moisture determination utilizes the specific reaction of Karl Fischer reagent (containing iodine, sulfur dioxide, and pyridine) with water in the presence of methanol to quantify the water content in a substance. Specifically, the volumetric titration method involves placing a titration solvent in a titration flask, dissolving the sample in the solvent to extract the water, and then titrating the sample with a Karl Fischer reagent primarily composed of iodine, sulfur dioxide, and an alkali to determine the water content.

[0190] Water reacts with iodine and sulfur dioxide in the presence of alkali and alcohol.

[0191] H2O+I2+SO2+CH3OH+3RN→2RN·HI+RN·HSO4CH3

[0192] As shown in the above formula, since H₂O and I₂ react in a 1:1 ratio, the number of milligrams (titer) of water per 1 ml of Karl Fischer reagent should be determined beforehand using water or a water standard. Then, the water content (mg) is calculated based on the required titration volume (ml) of Karl Fischer reagent for the sample determination.

[0193] Water content (mg) = Karl Fischer reagent titration volume (ml) × titer (mgH2O / ml)

[0194] Karl Fischer reagent is also known as KF reagent.

[0195] Furthermore, the water content relative to the total mass of the ink is calculated based on the calculated water content.

[0196] Moisture content (%) = (Water content in ink / Total mass of ink) × 100

[0197] As a means of setting the moisture content to 0.02% by mass or more and less than 1.50% by mass, examples include allowing the ink to stand in an open system in a constant temperature and humidity device, directly adding water, or adding hygroscopic agents such as molecular sieves or silica for preservation. By stirring during standing, moisture absorption and dehumidification can be promoted.

[0198] Examples of materials that can be used to hold ink with a desired moisture content include PET, polyvinyl chloride, ethylene-vinyl alcohol copolymer, metal components such as aluminum, nylon, LLDPE (linear low-density polyethylene), LDPE (low-density polyethylene), HDPE (high-density polyethylene), and PP (polypropylene). Among these materials, metal components such as aluminum, LLDPE, LDPE, HDPE, and PP are more preferred.

[0199] From the viewpoint of moisture permeability and barrier properties against gases such as oxygen, the wall thickness of the container is preferably 0.1 to 3 mm. Furthermore, the container is preferably colored to block ultraviolet and visible light.

[0200] Furthermore, from the viewpoint of maintaining moisture content, it is preferable to use a moisture-proof bag. Examples of materials for moisture-proof bags include PET, metal components such as aluminum, nylon, LLDPE (linear low-density polyethylene), LDPE (low-density polyethylene), HDPE (high-density polyethylene), and PP (polypropylene). As for the composition of the moisture-proof bag, it is preferable to laminate multiple layers of nylon, aluminum foil, and LLDPE together. From the viewpoint of moisture permeability and barrier properties against gases such as oxygen, it is more preferable to provide a layer composed of at least one of metal and metal compounds. The thickness of the moisture-proof bag is preferably 0.05 to 0.3 mm.

[0201] With regard to at least one of the contained containers or moisture-proof bags, the water vapor transmission rate of the container or moisture-proof bag is preferably 30 g / m³. 2 • Less than 24 hours. The water vapor transmission rate is more preferably 15 g / m³. 2 • Less than 24 hours, further preferred 10g / m 2 • Less than 24 hours, preferably 5.0 g / m 2 • Less than 24 hours. By using a membrane with a water vapor transmission rate within the above range, the increase in moisture content of the composition filling the package can be suppressed even during long-term storage. The water vapor transmission rate was measured at 40°C and 90% relative humidity.

[0202] From the viewpoint of etching resistance, the dissolved oxygen content of the ink disclosed herein is preferably 0.1 mg / L or more and less than 10.0 mg / L at 25°C. If it is 0.1 mg / L or more, the ink will not deteriorate during storage, and etching resistance can be easily obtained. If it is less than 10.0 mg / L, the curability will not deteriorate, and etching resistance and high-temperature copper etching resistance can be obtained.

[0203] Inks with a dissolved oxygen content of 0.1 mg / L or more but less than 10.0 mg / L at 25°C are preferably suitable for any of the following processes: filling ink cartridges, filling ink into inkjet recording devices, or filling inkjet heads.

[0204] Regarding dissolved oxygen levels, an optical handheld DO meter (manufactured by Hamilton) with an organic solvent compatibility can be used to measure the dissolved oxygen using a fluorescent membrane replacement cover ODO CAP H2.

[0205] Within the range where etching resistance is not reduced, the ink disclosed herein may also contain one or more metallic elements selected from alkali metals such as Li, Na, and K; alkaline earth metals such as Mg, Ca, and Ba; transition metals such as Mn, Zn, Fe, and Sn; and half-metals such as Si. By containing the aforementioned metals, for example, it can contribute to cost reduction through the reduction of refining processes for colorants such as dyes and materials, and improve the ink's shelf life.

[0206] The surface tension of the ink disclosed herein is preferably 60 mN / m or less, more preferably 20 to 50 mN / m, and even more preferably 25 to 45 mN / m. Regarding the surface tension, it is measured at 25°C using a surface tension meter, for example, using an automatic surface tension meter (product name "DY-300") manufactured by Kyowa Interface Science Co., Ltd., and measured using the plate method.

[0207] <Application>

[0208] The ink disclosed herein can be used in various fields such as metal processing, electronic circuits, printed circuit boards, plate making, nameplates, semiconductors, and color filters for the formation of insulating films, protective films, resist layers, and plated resist layers. The ink disclosed herein is preferably used for resist layers or plated resist layers. From the perspective of good peelability relative to alkaline stripping solutions, the ink disclosed herein is particularly preferred for use as a resist layer.

[0209] For use in the formation of a resist layer, the cured film formed by the ink needs to be removable by an alkaline stripping solution or the like. For use in the formation of a coated resist layer, the cured film formed by the ink can be removed by a stripping solution containing an organic solvent or the like.

[0210] [Inkjet Recording Method]

[0211] The inkjet recording method is an inkjet recording method that sprays active energy ray curable ink onto a substrate and cures it using active light. The ink disclosed above is used as the active energy ray curable inkjet ink.

[0212] The preferred substrate is a substrate having a metal film (oxide film) or a substrate without a metal film. In the following description, we will take the case where the substrate has an oxide film on its upper surface as an example.

[0213] Specifically, the inkjet recording method preferably includes: (1) a step of ejecting the ink from the nozzle of the inkjet head and causing it to land on an oxide film on a substrate; and (2) a step of irradiating the ink landed on the oxide film with active light to cure the ink.

[0214] The following describes a method for manufacturing a printed circuit board using the ink disclosed herein in the formation of the resist layer.

[0215] Figures 1-4 This diagram illustrates the manufacturing process of a printed circuit board in which the inks of this disclosure are used in the formation of the resist layer.

[0216] <(1) process>

[0217] exist Figure 1 In this process, a conductive oxide film 2 is formed on a substrate 1, which serves as a recording medium. Figure 1 On the oxide film 2 shown, ink droplets are ejected from the inkjet head 5 and landed at positions corresponding to the resist film 3 to be formed, thus patterning the resist film (see reference). Figure 2 ).

[0218] The inkjet head can eject ink in either on-demand or continuous mode.

[0219] On-demand inkjet heads can be any of the following types: single-chamber, dual-chamber, curved, piston, shared-mode, and shared-wall electromechanical conversion types, as well as thermal inkjet and BUBBLEJET (registered trademark) electrothermal conversion types. BUBBLEJET is a registered trademark of Canon Inc.

[0220] There are no particular limitations on the adhesive used for the liquid-wetting components of the inkjet head. Room-temperature curing adhesives, thermosetting adhesives that cure by heating to promote polymerization, and ray-curing adhesives that cure by irradiation with active energy rays such as ultraviolet light are all acceptable. Among these, thermosetting adhesives are preferred, for example, epoxy-based adhesives are preferred.

[0221] By ejecting ink droplets from the inkjet head while the ink is heated, ejection stability can be improved. The ink temperature during ejection is preferably in the range of 25 to 100°C, and more preferably in the range of 30 to 90°C to further improve ejection stability. In particular, ejection is preferably performed at an ink temperature where the ink viscosity is in the range of 8 to 15 mPa·s, more preferably in the range of 8 to 13 mPa·s.

[0222] For sol-gel phase change inks, to improve the ejectibility of the ink from the printhead, it is preferable to set the temperature of the ink when filling the printhead to (gelation temperature + 10) °C to (gelation temperature + 30) °C. If the temperature of the ink inside the printhead is lower than (gelation temperature + 10) °C, the ink will gel inside the printhead or on the nozzle surface, and the ejectibility of the ink will easily decrease. On the other hand, if the temperature of the ink inside the printhead exceeds (gelation temperature + 30) °C, the ink temperature becomes too high, and therefore the ink composition may deteriorate.

[0223] There are no particular restrictions on the method of heating the ink. For example, at least one of the following can be heated by plate heaters, belt heaters, or insulated water: the ink tank forming the head support, the ink supply system such as the supply pipe and the ink tank in front of the head, the piping with a filter, and the piezoelectric head.

[0224] From the perspective of recording speed and image quality, the amount of ink droplets ejected is preferably in the range of 2 to 20 pL.

[0225] The substrate is not particularly limited, and examples include copper-clad laminates using all grades (FR-4, etc.) of the following materials, other polyimide films, PET films, glass substrates, ceramic substrates, wafer boards, stainless steel (SUS), brass, aluminum substrates, etc. The materials used include copper-clad laminates for high-frequency circuits using materials such as paper phenolic resin, paper epoxy, glass cloth epoxy, glass polyimide, glass cloth / non-woven epoxy, glass cloth / paper epoxy, synthetic fiber epoxy, and fluoropolymer-polyethylene-PPO-cyanate ester. In particular, copper-clad laminates and aluminum substrates are preferred.

[0226] In addition, conductive oxide films include, for example, copper, gold, silver, aluminum, nickel, and ITO.

[0227] <(2) process>

[0228] In step (2), the ink that has settled on the oxide film in step (1) is irradiated with active light to form a resist film formed by curing the ink.

[0229] The active light source can be selected from electron beams, ultraviolet rays, alpha rays, gamma rays, and X-rays, with ultraviolet rays being preferred.

[0230] Ultraviolet irradiation can be performed, for example, using a water-cooled LED manufactured by Phoseon Technology at a wavelength of 395nm. By using an LED as the light source, it is possible to suppress poor ink curing caused by ink melting due to radiant heat from the light source.

[0231] The peak irradiation of the resist film surface with ultraviolet light having a wavelength in the range of 360~410nm is preferably 0.5~10W / cm. 2 Within the range, more preferably 1~5W / cm 2 The method is carried out within a certain range. From the viewpoint of suppressing radiant heat from reaching the ink, the amount of light irradiating the resist film is preferably 350 to less than 3000 mJ / cm. 2 .

[0232] The irradiation with active light can be performed between 0.001 and 60 seconds after the ink is applied. Preferably, the irradiation with active light is performed between 0.001 and 1.0 seconds after the ink is applied, and more preferably between 0.001 and 0.5 seconds in order to form a high-precision resist film.

[0233] The irradiation of active light can be carried out in two stages.

[0234] First, the ink can be temporarily cured by irradiating it with active light within 0.001 to 2.0 seconds after ink application. After all printing is completed, the ink is further irradiated with active light to fully cure it. By dividing the irradiation with active light into two stages, shrinkage of the recording material that occurs during ink curing is made less likely.

[0235] As described above, the resist film is formed using an inkjet printing method.

[0236] After the resist film is formed, the resist pattern, such as circuits, patterns, text, and images, is obtained on the substrate through etching.

[0237] (Etching process)

[0238] Regarding the etching process, the oxide film 2 not covered by the resist film 3 is first removed using an acid etching solution (see reference). Figure 3 Furthermore, an alkaline stripping solution is used to peel off the resist film 3 covering the oxide film 2, thereby obtaining fine and high-precision line drawings of circuits, patterns, text, and images (see reference). Figure 4 ).

[0239] As a reaction mechanism of wet etching using liquids, etching is achieved by corroding and removing the substrate. For example, if the substrate is metal, etching is achieved by forcibly corroding it by oxidizing and dissolving the metal.

[0240] In this disclosure, etch resistance refers to the ability of a substrate with a cured film (resist film) to remain on the substrate even when immersed in an etching solution, without peeling off, thus demonstrating its resistance to the etching solution. The cured film formed using the ink of this disclosure exhibits excellent etch resistance because it does not peel off even when in contact with the etching solution.

[0241] Examples of etching solutions include ferric chloride aqueous solution, copper chloride aqueous solution, copper ammonia solution, high-concentration sodium hydroxide aqueous solution, high-concentration hydrochloric acid, hydrofluoric acid, and ferric nitrate aqueous solution.

[0242] The etching solutions illustrated above can be used individually or in combination. Etching processes can be performed, for example, at temperatures between 40 and 60°C.

[0243] For example, for etching copper, it is preferable to primarily use an aqueous solution of ferric chloride. If copper is immersed in an aqueous solution of ferric chloride, the copper dissolves in the ferric chloride solution, and iron is replaced by copper to form copper chloride, thereby etching the copper substrate.

[0244] Examples of alkaline stripping solutions include aqueous solutions of sodium hydroxide, potassium hydroxide, tetramethylammonium hydroxide, sodium (metasilicate) silicate, and silicate solutions (aqueous solutions containing silicates).

[0245] The ink disclosed herein can also be used to form a resist layer.

[0246] Figures 5-8 This is a diagram illustrating the manufacturing process of a printed circuit board in which the ink of this disclosure is used to form a resist layer.

[0247] Similar to the formation of the resist layer described above, ink droplets are ejected from the inkjet head 5 onto the substrate 1, which serves as the recording medium (see reference). Figure 5 Then, it is placed at the position corresponding to the coating resist film 3a to be formed, and patterned (see reference). Figure 6 ).

[0248] Next, active light is irradiated onto the falling ink to form a coated resist film 3a that is cured by the ink.

[0249] After the formation of the coated resist film 3a, as Figure 7 As shown, the following plating process is performed on substrate 1 to form plating layer 4.

[0250] (Platinum coating)

[0251] For plating processing, any of the acidic, neutral, and alkaline baths suitable for electroplating, electroless plating, and non-electrolytic plating can be used. Electroless plating is preferred as the plating process, and an acidic bath is also preferred. Through the plating process, a coating is formed on the portion of the metal layer exposed on the surface of the substrate (the portion other than the coating resist film).

[0252] The coating may be formed from metals such as gold, silver, platinum, rhodium, palladium, copper, and nickel, but is not limited to these.

[0253] The preferred plating process includes nickel plating and gold plating. Nickel plating is preferred from the viewpoint of protecting copper, and it is also preferred from the viewpoint of being suitable for formation during the soldering process. Gold plating is preferred from the viewpoint of the long-term stability of the nickel plating layer.

[0254] Specifically, the plating process preferably includes a degreasing process using a weak alkaline solution, an acid pickling process, a palladium activation process, a nickel plating process, and a gold plating process.

[0255] Since the above plating process includes immersion in acidic solutions and high-temperature immersion at around 60~90°C, the properties of the cured film are such that a coating with both acid resistance and heat resistance is formed, thus improving the plating resistance.

[0256] After coating 4 is formed, as Figure 8 As shown, the resist film 3a, excluding the coating 4, is stripped using an organic solvent, an aqueous stripping solution containing an organic solvent (an aqueous stripping solution containing a solvent), etc.

[0257] As a usable organic solvent, it can be used not only with solvents that are easily soluble in water, but also with organic solvents that are poorly soluble or insoluble in water.

[0258] Specific examples of organic solvents include straight-chain, branched, secondary, or polyols such as ethanol, propanol, 2-propanol, butanol, hexanol, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, butanediol, trimethylolpropane, neopentyl glycol, glycerol, 1,2,4-butanetriol, 1,2-butanediol, 1,4-butanediol, and diacetone alcohol; ethylene glycol monomethyl ether and ethylene glycol monoethyl ether. Ethylene glycol monobutyl ether and other ethylene glycol alkyl ethers; diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, triethylene glycol monomethyl ether and other polyethylene glycol alkyl ethers; propylene glycol monomethyl ether and other propylene glycol alkyl ethers; dipropylene glycol monomethyl ether and other polypropylene glycol alkyl ethers; ethylene glycol monomethyl ether acetate, diethylene glycol monomethyl ether acetate, propylene glycol monomethyl ether acetate, dipropylene glycol monomethyl ether acetate, glycerol monoacetate, Acetates such as glyceryl diacetate; lactates such as ethyl lactate and butyl lactate; adipates such as diethyl adipate and dibutyl adipate; phthalates such as diethyl phthalate and dibutyl phthalate; dialkyl glycol ethers such as diethylene glycol diethyl ether; ketones such as methyl ethyl ketone, cyclohexanone, and isophorone; aromatic hydrocarbons such as toluene and xylene; aromatic alcohols such as benzyl alcohol; petroleum-based aromatic mixed solvents such as the Swasol series (manufactured by Maruzen Petrochemical Co., Ltd.) and the Solvesso series (manufactured by Exxon Chemical Co., Ltd.); or n-hexane, cyclohexane, tetrahydrofuran, 1-methyl-2-pyrrolidone (N-methyl-2-pyrrolidone), methyl ethyl ketone, 2-pyrrolidone, γ-butyrolactone, N,N-dimethylformamide, 1,3-dimethyl-2-imidazolinone, dimethyl sulfoxide, dimethylacetamide, etc. These organic solvents can be used individually or in combination of two or more appropriately.

[0259] Among the above-mentioned organic solvents, preferred are aromatic alcohols such as benzyl alcohol, 1-methyl-2-pyrrolidone (N-methyl-2-pyrrolidone), 2-pyrrolidone, γ-butyrolactone, N,N-dimethylformamide, 1,3-dimethyl-2-imidazolinone, dimethyl sulfoxide, methyl ethyl ketone, and dimethylacetamide.

[0260] The preferred organic solvents are aromatic alcohols such as benzyl alcohol, 1-methyl-2-pyrrolidone, and 2-pyrrolidone.

[0261] Examples of commercially available aqueous stripping solutions containing solvents include Anlast CB, Anlast 612-T, Anlast No.1D (manufactured by Miwaka Junya Research Institute Co., Ltd.), CLEANTHROUGH LC-841, and CLEANTHROUGH PA-900 (manufactured by Kao Corporation).

[0262] When peeling off the resist film using an alkaline solution after the etching treatment, or when peeling off the plating resist film using a stripping solution containing an organic solvent after the plating treatment, methods such as immersion, spraying, immersion and ultrasonic irradiation can be used.

[0263] When using an immersion method for peeling, the substrate can be immersed in an alkaline solution or a peeling liquid containing an organic solvent at 40-60°C for 1-60 minutes. This operation can be performed once or multiple times. Furthermore, after the peeling process, the substrate can be cleaned with the alkaline solution, organic solvent, or other solvent used in the peeling process.

[0264] Example

[0265] The following examples illustrate the present disclosure in detail, but the disclosure is not limited to these examples. It should be noted that, unless otherwise specified, the operation is performed at room temperature (25°C) in the following examples. Furthermore, unless otherwise specified, "%" and "parts" refer to "mass %" and "parts by mass," respectively.

[0266] Materials for inkjet inks

[0267] The following materials are used as inkjet ink materials.

[0268] [Table 1]

[0269]

[0270] The structures of the compounds shown in Table I above are shown below.

[0271] [Chemistry 9]

[0272]

[0273] <Preparation of acrylic polymeric compound (B)>

[0274] In the preparation of the acrylic polymeric compound (B), the reaction product (D) obtained in the following reaction is separated by high performance liquid chromatography (HPLC).

[0275] First, in a three-necked reactor equipped with a temperature probe and a reflux condenser, 100g of 98% acrylic acid (manufactured by Toa Synthetic Co., Ltd.), 20% of Amberlyst A15 resin, and 1000ppm of hydroquinone methyl ester as a polymerization inhibitor were added. Then, the reaction medium was stirred at 125°C while being bubbled with air to obtain the reaction product (D).

[0276] The HPLC conditions are as follows.

[0277] Column: InertSustain C18 (5μm, 150×4.6mm ID)

[0278] 40 degrees

[0279] Elution buffer: A) 0.1M sodium phosphate buffer (pH 2.5) 95%

[0280] B) Acetonitrile 5%

[0281] Gradient: 0 minutes (B: 5%) - 5 minutes (B: 5%) - 15 minutes (B: 40%) - 20 minutes (B: 40%)

[0282] Flow rate: 1.0 mL / min

[0283] Detection: UV210nm

[0284] Sample concentration: approximately 1500 ppm

[0285] The peak around elution time 13.5 minutes was recovered under the above conditions to obtain the acrylic polymer (B).

[0286] <Preparation of acrylic polymeric compound (C)>

[0287] In the preparation of the acrylic polymeric compound (C), the reaction product (D) obtained in the above reaction is separated by high performance liquid chromatography (HPLC).

[0288] The HPLC conditions are as follows.

[0289] Column: InertSustain C18 (5μm, 150×4.6mm ID)

[0290] 40 degrees

[0291] Elution buffer: A) 0.1M sodium phosphate buffer (pH 2.5) 95%

[0292] B) Acetonitrile 5%

[0293] Gradient: 0 minutes (B: 5%) - 5 minutes (B: 5%) - 15 minutes (B: 40%) - 20 minutes (B: 40%)

[0294] Flow rate: 1.0 mL / min

[0295] Detection: UV210nm

[0296] Sample concentration: approximately 1500 ppm

[0297] Using the above conditions, the peak around elution time of 15 minutes was recovered to obtain the acrylic polymeric compound (C).

[0298] [Ink Preparation]

[0299] The ink components listed in Tables II to V below are mixed, and the mixture is heated to 80°C while being filtered through a 3μm Teflon membrane filter manufactured by DVANTEC to obtain inks 1 to 25.

[0300] [Table 2]

[0301]

[0302] [Table 3]

[0303]

[0304] [Table 4]

[0305]

[0306] [Table 5]

[0307]

[0308] [Patterns formed using inkjet printing]

[0309] The prepared ink is filled into an inkjet recording device having an inkjet recording head equipped with piezoelectric inkjet nozzles. The inkjet recording head used is a KM1800iSHC-C (manufactured by Konica Minolta Corporation). Using this device, patterns are formed on a copper-clad laminate (FR-4, 1.6 mm thick, 150 mm × 95 mm in size) for printed wiring boards.

[0310] The ink supply system includes an ink reservoir, ink flow path, a secondary ink reservoir in front of the inkjet printhead, piping with a metal filter, and a piezoelectric head. The ink is heated to 80°C from the ink reservoir to the printhead. The ink inside the printhead is then heated to 80°C using an inkjet head with a built-in heater.

[0311] Using an inkjet recording device, a solid pattern of 20mm × 50mm was printed on the substrate at a droplet size of 6.0pl to a thickness of 20μm. Then, a Fire Jet™ FJ100 (manufactured by Phoseon Technology, wavelength 395nm) was used at a wavelength of 2W / cm². 2 3000mJ / cm 2 The ink layer is cured by irradiation to obtain a cured film.

[0312] [evaluate]

[0313] <Dye leaching properties in etching solution>

[0314] For the cured film sample, after immersion in ferric chloride aqueous solution at 60°C for 30 minutes, it was washed with water, dried, and the color change of the cured film was visually observed to confirm whether the color had become lighter compared to the cured film before immersion in the solution. The dye solubility was evaluated according to the following criteria, and criteria A and B were considered to be practically sound.

[0315] (Benchmark)

[0316] A: No color variation.

[0317] B: The end of the cured film has faded slightly (color has peeled off).

[0318] C: The cured film becomes lighter overall (color peels off).

[0319] D: The color completely fades and becomes colorless.

[0320] <Dye solubility in alkaline stripping solution>

[0321] For the sample of the cured film, after immersion in a 3% sodium hydroxide aqueous solution at 40°C for 2 minutes, the color change of the release solution and the released film was visually observed. The dye leaching performance was evaluated according to the following criteria, and criteria A, B, and C were considered practically acceptable.

[0322] (Benchmark)

[0323] A: No color variation.

[0324] B: The peeling solution caused discoloration, and a portion of the peeled-off cured film became slightly lighter in color (color flaking off).

[0325] C: The stripping solution has a strong color, and the cured film after stripping becomes lighter in color (color peeling off).

[0326] D: The color of the peeled-off cured film completely falls off and becomes colorless.

[0327] <Etching Resistance>

[0328] For the samples of the cured film, after immersion in an aqueous ferric chloride solution at 60°C for 30 minutes, washing with water and drying, adhesive tape was applied, and the film was peeled off to observe the peeling state of the cured film. Etching resistance was evaluated according to the following criteria. Criteria A, B, and C below are considered practically feasible.

[0329] (Benchmark)

[0330] A: No peeling occurred.

[0331] B: No peeling occurred, but there was a slight discoloration.

[0332] C: The end peels slightly, but most of it retains the cured film and does not peel off.

[0333] D: Delamination occurs across the entire surface.

[0334] <Alkali-stripping properties>

[0335] For the samples of the cured film after etching resistance, after immersion in a 3% sodium hydroxide aqueous solution at 40°C, washing with water, and drying, the peelability of the cured film is visually observed. Alkali peelability is evaluated according to the following criteria. Criteria A, B, and C below are considered to be practically sound.

[0336] (Benchmark)

[0337] A: Peel off within 1 minute.

[0338] B: Peel off within 1 minute but less than 2 minutes.

[0339] C: Peel off within 2 to 3 minutes.

[0340] D: No peeling occurred even after soaking for more than 3 minutes.

[0341] <Removing the seal>

[0342] The desealing property of ink refers to its ability to maintain its fluidity when exposed to external air. Quantitative measures of this property include the desealing time required to keep the nozzle face uncovered until the nozzle face of the recording head becomes clogged or blocked; the ink ejection rate when the nozzle face is uncovered; the time the nozzle face is left uncovered for a specified period; and the rate of decrease in ink ejection rate after the specified time. In other words, desealing property is an indicator of how easily the ink dries.

[0343] Here, the desealing performance is evaluated based on the rate of decrease in ink ejection speed after a specified time.

[0344] Regarding desealing performance, under conditions of 75°C and 20% RH, various inks were loaded into an inkjet recording device with a piezoelectric head having a nozzle orifice diameter of 20 μm, a drive frequency of 10 kHz, and 128 nozzles. Then, an intermittent operation was performed, with continuous ejection for 20 seconds, a 5-second pause, and then continuous ejection, under the condition of ejection at a velocity of 6 m / s at a distance of 0.5 mm from the nozzle surface. The rate of decrease in initial ejection velocity after ejection stopped was measured, and desealing performance was evaluated according to the following criteria. Criteria A and B below are considered to be practically sound.

[0345] (Benchmark)

[0346] A: The speed reduction rate is less than 5%.

[0347] B: The rate of speed reduction is greater than 5% but less than 10%.

[0348] C: The rate of speed reduction is greater than 10%.

[0349] [Table 6]

[0350]

[0351] As the results above show, it is believed that compared with the ink of the comparative example, the ink of this embodiment can prevent the leaching of dye and has excellent etching resistance and alkali stripping properties.

[0352] In addition, when the acrylic acid content is below 15%, it can be confirmed that the ink ejection speed decreases little after a specified time and the desealing property is good.

[0353] Explanation of reference numerals in the attached figures

[0354] 1: Substrate

[0355] 2: Oxide film

[0356] 3: Resist film

[0357] 3a: Applying a resist film

[0358] 4: Coating

[0359] 5: Inkjet head

Claims

1. An active energy ray curable inkjet ink, characterized in that, contain: Dyes containing amino groups; acrylic acid; In the following general formula (1), n ​​represents 1 acrylic polymer (A); and In the following general formula (1), n ​​represents 2 acrylic polymeric compound (B). [Chemistry 1] 。 2. The active energy ray curable inkjet ink according to claim 1, characterized in that, The acrylic polymeric compound (C) containing an acrylic polymeric compound (C) in which n represents 3 in the general formula (1) is present in an amount of 0.1% by mass or more.

3. The active energy ray curable inkjet ink according to claim 1, characterized in that, It contains monomers with acrylamide groups.

4. The active energy ray curable inkjet ink according to claim 1, characterized in that, As a photopolymerization initiator, it contains a polymerization initiator with an acylphosphine structure.

5. The active energy ray curable inkjet ink according to claim 1, characterized in that, It contains a multifunctional monomer, wherein the content of the multifunctional monomer is less than 30% by mass.

6. The active energy ray curable inkjet ink according to claim 1, characterized in that, It contains polymerizable monomers with an alicyclic structure.

7. The active energy ray curable inkjet ink according to claim 1, characterized in that, The content of acrylic acid is less than 15% by mass.

8. The active energy ray curable inkjet ink according to claim 1, characterized in that, The dye is a salt of a compound having a triarylmethane structure, and the molecular weight of the counter anion is 100 or higher.

9. The active energy ray curable inkjet ink according to claim 1, characterized in that, It contains a gelling agent.

10. The active energy ray curable inkjet ink according to claim 1, characterized in that, Used for the resist layer.

11. The active energy ray curable inkjet ink according to claim 1, characterized in that, Used for applying a resist layer.

12. An inkjet recording method, comprising spraying an active energy ray-cured inkjet ink onto a substrate and curing it using active light, characterized in that, The active energy ray curable inkjet ink according to any one of claims 1 to 11 is used as the active energy ray curable inkjet ink.

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