JP5608491B2 - Method for forming conductive pattern and printed matter - Google Patents

Description

  Embodiments described herein relate generally to a conductive pattern forming method and a printed matter.

  As a method for forming a conductive pattern on a substrate, a printing method has attracted attention. In such a method, a conductive material for printing such as a conductive paste and metal nanoparticle ink is used. Since the formation of the conductive pattern by the printing method does not require a step such as etching by photolithography, the manufacturing apparatus is simplified. Since no waste liquid such as developer or etching liquid is generated, the environmental load can be reduced.

However, the conductive pattern formed on the substrate by the printing method does not necessarily have sufficient adhesion to the substrate.
JP 2008-72052 A

  An object of this invention is to provide the method of forming the conductive pattern which has sufficient adhesiveness with respect to a base material by a printing method.

  The conductive pattern forming method of the embodiment includes a first ink containing a cationically polymerizable compound and a photoacid generator, and a second ink containing conductive particles or particles that exhibit conductivity by sintering. And use. The method includes forming a first ink layer with a first ink on an insulating substrate, irradiating the first ink layer with ultraviolet rays to obtain a cured film of a thermoplastic resin, and the curing. Printing a second ink on the film in a predetermined pattern, obtaining a second ink layer so that the whole does not directly contact the insulating substrate, and firing the second ink layer; It is characterized by comprising. The cured film of the thermoplastic resin forms a conductive pattern as a sintered body of the particles by firing the second ink layer obtained by polymerizing the cationic polymerizable compound.

It is a figure which shows 1 process of the formation method of the conductive pattern of one Embodiment. It is a figure which shows the process following FIG. FIG. 3 is a diagram showing a step following FIG. 2.

  Embodiments of the present invention will be described below.

  In the method for forming a conductive pattern of this embodiment, first, a first ink layer 2 is formed on an insulating substrate 1 as shown in FIG.

  As the insulating base material 1, a normal resin substrate and a glass substrate can be used. When manufacturing a circuit board, either a rigid board or a flexible board may be used. The material of the rigid substrate can be selected from, for example, bakelite, phenol, paper epoxy, glass epoxy, alumina, and ceramics. The material of the flexible substrate can be selected from, for example, polyimide, liquid crystal polymer, and polyester.

  When used for a display or the like, glass and a flexible substrate can be used. The material of the flexible substrate is, for example, ultra-thin glass, saturated polyester (PET) resin, polyethylene naphthalate (PEN), crosslinked fumaric acid diester resin, polycarbonate (PC) resin, polypropylene (PP), polyethersulfone ( PES), polysulfone (PSF, PSU), polyarylate (PAR), cyclic polyolefin (COP, COC), cellulose resin, polyamideimide (PAI) resin, maleimide-olefin resin, polyamide (PA) resin, acrylic resin , Epoxy resins, silicone resins, polybenzazole resins, episulfide compounds, cyanate resins, aromatic ether resins, and the like.

  The insulating base as described above can be used not only as a single layer but also as a laminate. In this case, a conductive layer such as a circuit pattern may be provided between the insulating base materials. If the surface is an insulating base material, it is referred to as an insulating base material in this specification.

  A silicon substrate used for a solar cell or the like can also be used as the insulating substrate 1.

  Before the first ink layer 2 is formed, the insulating substrate 1 is preferably subjected to a surface treatment. By applying the surface treatment, the wettability of the first ink is enhanced. As a result, the contact angle of the first ink with respect to the insulating substrate 1 can be reduced. The surface treatment method can be appropriately selected according to the material of the insulating base material 1 and the like. For example, in the case of an insulating substrate made of glass, surface treatment can be performed by a plasma surface treatment apparatus, a UV ozone surface treatment apparatus, or the like.

  The first ink layer 2 is formed of the first ink, and the first ink contains a binder for ensuring the adhesion of the conductive pattern to the insulating substrate 1. As the binder, a monomer that can be cured by a polymerization reaction can be used. The monomer that cures by polymerization is specifically a photocurable cationic polymerizable compound.

  The cationically polymerizable compound is crosslinked or polymerized by the action of an acid generated from the photocationic polymerization initiator by light irradiation. After polymerization, a cured film of thermoplastic resin is obtained. Here, the term “thermoplastic” means that it can be reflowed by heat, and the time for maintaining the property may be a short time. It is desirable that the cationically polymerizable compound alone has a fluidity of about 100 mPa · sec or less at 50 ° C.

  Examples of the cationic polymerizable compound include compounds having a molecular weight of 1000 or less and having cyclic ether groups such as epoxy groups, oxetane groups, and oxolane groups. The above-described substituents may be introduced into the side chain of the following compound. For example, it is a compound selected from acrylic compounds, vinyl compounds, carbonate compounds, low molecular weight melamine compounds, vinyl ethers and vinyl carbazoles, styrene derivatives, alpha-methyl styrene derivatives, and vinyl alcohol esters. Vinyl alcohol esters are ester compounds of vinyl alcohol and acrylic or ester compounds of vinyl ether and methacryl.

  The cationically polymerizable compound can have an aliphatic skeleton or an alicyclic skeleton. When such a polymerizable compound is used, the transparency of the ink at the time of exposure is increased. As a result, appropriate thermoplasticity and re-dissolvability can be imparted to the cured film. In addition, sensitivity, fixability and maintainability are improved. Maintainability means a reduction in problems caused by volatilization of ink components in a printing apparatus such as an inkjet head during printing.

  In particular, when an epoxy compound having an alicyclic skeleton is used as the cationic polymerizable compound, it can have a certain high boiling point and low viscosity in addition to the reactivity. Specifically, the boiling point is about 150 ° C. or more, and the viscosity is about 50 mPa · sec or less at a temperature of 50 ° C. or less.

  Among the compounds described above, oxirane compounds, oxetane compounds, and vinyl ether compounds are preferred.

  As the oxirane compound, any compound generally known as an epoxy resin can be used. Specific examples include monomers, oligomers, and polymers of epoxides selected from aromatic epoxides, alicyclic epoxides, aliphatic epoxides, and the like.

  More specifically, for example, an alicyclic epoxy exemplified by Celoxide 2021, Celoxide 2021A, Celoxide 2021P, Celoxide 2081, Celoxide 2000, and Celoxide 3000 manufactured by Daicel Chemical Industries; (meth) acrylate compound having an epoxy group Methacrylate having methyl glycidyl group such as certain cyclomer A200, cyclomer M100, and MGMA; glycidol, β-methylepicholorhydrin, α-pinene oxide; α-pinene oxide; α-pinene oxide; Epoxidized soybean oil such as olefin monoepoxide, α-olefin monoepoxide having 16 to 18 carbon atoms, and Daimac S-300K; Epoxidized linseed oil such as Daimac L-500; 01, and such a polyfunctional epoxy such as Epolead GT401 and the like.

  Moreover, the following compounds can be used. Silacure (American Dow Chemical Co., Ltd., alicyclic epoxy); a compound in which a hydroxyl group terminal of a low molecular phenol compound that has been hydrogenated and made aliphatic is substituted with a group having an epoxy; glycidyl ester of hexahydrophthalic acid, and water And glycidyl ester of an aromatic polyvalent carboxylic acid. Furthermore, glycidyl ether compounds of alcohols selected from polyhydric aliphatic alcohols and alicyclic alcohols can also be used. Specific examples of the alcohol include ethylene glycol, glycerin, neopentyl alcohol, hexanediol, and trimethylolpropane.

  Epoxy compounds having an alicyclic skeleton have a certain high boiling point and low viscosity in addition to reactivity. For this reason, it is suitable when forming the 1st ink layer 2 by inkjet printing.

  Among the alicyclic epoxy compounds, those having a relatively low weight average molecular weight do not have high mutagenicity by the AMES test. Specifically, Celoxide 3000 or the like. If it is an alicyclic epoxy compound whose weight average molecular weight is 150-300, desired mutagenicity can be maintained and storage stability is not impaired.

  A polymeric compound can be comprised only with an epoxy compound, for example. In this case, the content of the oxirane compound is preferably 30% by weight or more of the entire first ink. When 30% by weight or more of the entire first ink is an oxirane compound, there is no fear of an increase in viscosity or a decrease in thermoplasticity. The content of the oxirane compound is more preferably 40% by weight or more of the entire first ink.

  The cationically polymerizable compound may be composed of an oxirane compound, an oxetane compound, and a vinyl ether compound. The content of the oxirane compound is desirably 30% by weight or less of the entire polymerizable compound. When a polymerizable compound containing an oxirane compound is used within such a range, a cured product having sufficient adhesion and solvent resistance to the substrate can be formed. As for content of an oxirane compound, 3 to 20 weight% of the whole polymeric compound is more preferable.

  As the oxetane compound, a compound having two oxetane rings and a compound having one oxetane ring can be used. Examples of the compound having two oxetane rings include di [1-ethyl (3-oxetanyl)] methyl ether, 1,4-bis [(1-ethyl-3-oxetanyl) methoxy] benzene, 1,3-bis. [(1-ethyl-3-oxetanyl) methoxy] benzene, 4,4′-bis [(3-ethyl-3-oxetanyl) methoxy] biphenyl, 1,4-bis {[(3-ethyl-3-oxetanyl) Methoxy] methyl} benzene, bis [(1-ethyl-3-oxetanyl) methoxy] cyclohexane, bis [(1-ethyl-3-oxetanyl) methoxy] norbornane, and the like.

  Examples of the compound having one oxetane ring include 3-ethyl-3- (phenoxymethyl) oxetane, 3-ethyl-3- (2-ethylhexyloxymethyl) oxetane, 3-ethyl-3-hydroxymethyloxetane, [(1-ethyl-3-oxetanyl) methoxy] cyclohexane, oxetanylsilsesquioxane and the like.

  An acrylic compound having an oxetane group in the side chain, a methacryl compound having an oxetane group in the side chain, and the like can also be used. When such a compound is contained, an increase in the viscosity of the first ink can be suppressed. In addition, the curing of the ink is accelerated as in the case of the oxetane compound.

  In order to obtain a cured film having better adhesion to the substrate, it is preferable to use 3-ethyl-3- (phenoxymethyl) oxetane. By using the first ink containing 3-ethyl-3- (phenoxymethyl) oxetane, the adhesion to plastic materials such as PET, PP, PC, and substrates made of various materials such as glass is further increased. A high cured film can be formed. Note that the first ink containing 3-ethyl-3- (phenoxymethyl) oxetane can also improve adhesion to various metals such as stainless steel (SUS), copper, and aluminum.

  When a bifunctional oxetane compound is used, the solvent resistance of the cured product is further improved. The oxetane compounds may be used alone or in combination of two or more.

  When the polymerizable compound is constituted by the oxirane compound, the oxetane compound, and the vinyl ether compound, the oxirane compound can occupy 30% by weight or less of the total amount of the polymerizable compound. Under the present circumstances, it is preferable that content of an oxetane compound shall be 20 to 60 weight% of the total amount of a polymeric compound.

  By using the first ink in which the oxirane compound and the oxetane compound are contained in such amounts in the polymerizable compound, it is possible to form a cured film with further improved film strength without impairing adhesion.

As the vinyl ether compound, a vinyl ether compound represented by the following general formula (1) is used.

In the general formula (1), R ¹¹ is selected from the group consisting of a vinyl ether group, a group having a vinyl ether skeleton, an alkoxy group, a hydroxyl group-substituted product, and a hydroxyl group. However, at least one R ¹¹ has a vinyl ether group or a vinyl ether skeleton. R ¹² is a p + 1 valent group having a substituted or unsubstituted cyclic skeleton or aliphatic skeleton, and p is a positive integer including 0.

p is 0, when the cyclohexane ring skeleton is introduced as R ¹² is preferably contained oxygen atom in R ^12. Thereby, volatility can be suppressed low. Specifically, at least one carbon atom contained in the cyclohexane ring skeleton is desirably a structure having a ketone structure, a structure substituted with an oxygen atom, or a structure having an oxygen-containing substituent.

  Vinyl ether compounds bonded to methylene groups such as aliphatic glycol derivatives and cyclohexanedimethanol are generally well known. Such a polymerization reaction of the vinyl ether compound is significantly inhibited by the particles. Moreover, since the viscosity is relatively high, it has been difficult to prepare inks containing such vinyl ether compounds and particles.

  In the vinyl ether compound represented by the general formula (1), at least one vinyl ether group is directly bonded to an alicyclic skeleton, a cyclic ether compound, a terpenoid skeleton, or an aromatic skeleton. For this reason, even if it contains simultaneously with particle | grains, it is excellent in hardening performance.

In the general formula (1), examples of the (p + 1) -valent organic group R ¹² include, for example, a (p + 1) -valent group including a benzene ring, a naphthalene ring, and a biphenyl ring, a cycloalkane skeleton, a norbornane skeleton, an adamantane skeleton, And (p + 1) -valent groups derived from bridged alicyclic compounds such as a cyclodencan skeleton, a tetracyclododecane skeleton, a terpenoid skeleton, and a cholesterol skeleton.

  The content of the vinyl ether compound as described above is desirably 50% by weight or less of the total amount of the cationic polymerizable compound. Within such a range, the thermoplasticity of the formed cured film can be maintained.

  Specific examples of the vinyl ether compound include cyclohexane (poly) ol, norbornane (poly) ol, tricyclodecane (poly) ol, adamantane (poly) ol, benzene (poly) ol, naphthalene (poly) ol, anthracene ( Examples thereof include compounds in which a hydrogen atom of a hydroxyl group in an alicyclic polyol or phenol derivative such as poly) ol or biphenyl (poly) ol is substituted with a vinyl group.

  Moreover, the compound etc. which substituted the hydrogen atom of the hydroxyl group in polyphenol compounds, such as polyvinyl phenol and phenol novolak, by the vinyl group can also be used as a vinyl ether compound. In the vinyl ether compound as described above, a part of the hydroxyl group may remain. Alternatively, there is no problem even if some of the methylene atoms of the alicyclic skeleton are oxidized or substituted with ketone groups, lactones, oxygen atoms, or the like. In such a case, the volatility decreases, which is desirable.

  In particular, cyclohexyl monovinyl ether compounds are highly volatile. For this reason, when a cyclohexyl monovinyl ether compound is used, it is desirable that the cyclohexane ring is oxidized to at least a cyclohexanone ring or the like.

  More preferred are cyclic ether compounds having a substituent containing a vinyl ether structure. In terms of curability and safety, a cyclic ether skeleton having a bridged structure or a spiro structure together with a 5-membered ring containing an oxygen atom as a ring constituent atom is most preferable. Such a vinyl ether compound can be synthesized by using a corresponding alcohol compound and a vinyl ether source as starting materials, and substituting a hydroxyl group of the alcohol compound with a vinyl ether group using a catalyst. J. et al. Am. Chem. Soc. Vol 124, no. 8, 1590-1591 (2002) describes using vinyl acetate or propenyl ether as a vinyl ether source and using iridium chloride as a catalyst.

  Many skeletons such as terpenoid skeletons and norbornane skeletons exist in nature. Epoxy compounds, oxetane compounds, and vinyl ether compounds having such a skeleton are favorable in terms of cost.

Examples of such cyclic ether compounds are shown below. When an ink containing a vinyl ether compound having a ring structure is used, the adhesion of the coating film to the substrate is not lowered. Moreover, a vinyl ether compound having a ring structure is advantageous in that the ultimate hardness does not decrease.

  On the other hand, as a vinyl ether compound having no ring structure, specifically, a vinyl ether compound having a poly (alkylene glycol) skeleton having relatively low volatility is generally well known. Specifically, triethylene glycol divinyl ether is often used as an inexpensive compound.

  The cyclic compound having a substituent containing a vinyl ether structure preferably accounts for 30% by weight or more of the entire cationic polymerizable compound. When the above cyclic compound is contained in such an amount, a cured film having sufficient hardness and solvent resistance can be obtained.

  The vinyl ether compounds may be used alone or in combination of two or more.

  It is desirable that at least one of the oxetane compound and the above-described vinyl ether compound is a monofunctional compound. By containing a monofunctional compound, the shrinkage of the obtained cured product can be controlled. By adding the monofunctional compound at an appropriate content, shrinkage that occurs during the curing process of the polymerizable compound is suppressed, and as a result, the adhesion of the cured product is enhanced.

  The monofunctional compound content preferably occupies 20 to 70% by weight of the total amount of the cationically polymerizable compound. In the case of using an ink containing a polymerizable compound containing a monofunctional compound within such a range, a cured product having sufficient hardness as well as adhesion to the substrate can be formed. It is more preferable that the monofunctional compound accounts for 30 to 50% by weight of the total amount of the cationic polymerizable compound.

  For example, a polymerizable compound blended in a formulation of 20 to 40% by weight of a monofunctional oxetane compound, 10 to 30% by weight of a bifunctional oxetane compound, 3 to 20% by weight of an oxirane compound, and 30 to 50% by weight of a vinyl ether compound is preferable. By using the first ink containing such a polymerizable compound, a cured film having even better strength and solvent resistance can be formed.

  When the bifunctional oxetane compound is contained in the cationically polymerizable compound, the degree of crosslinking of the cured film is increased, so that the solvent resistance is greatly enhanced. When 18% by weight or more of the cationic polymerizable compound is a bifunctional oxetane compound and 30% by weight or less is 30% by weight or less of the monofunctional oxetane compound, the following characteristics are obtained. . Specifically, when the heating after light irradiation is performed at 120 ° C. or less, the adhesiveness does not appear immediately after the heating, and the adhesiveness appears when left for several days. After the second ink described later is applied on the cured film, the adhesion of the cured film is manifested. And since the stress by hardening shrinkage is relieved, the curvature and deformation | transformation of a cured film are suppressed.

  Any polymerizable compound as described above can be used as long as it has fluidity at room temperature. An appropriate viscosity may be appropriately selected according to the printing method applied to the application of the first ink. A viscosity range of 0.1 Pa · sec to 500 Pa · sec is used for screen printing and the like, and a viscosity of 1 mPa · sec to 50 mPa · sec is used for inkjet printing and the like. The viscosity of the ink can be measured using, for example, a cone plate viscometer.

  In addition, a general-purpose thermoplastic resin can be mix | blended with the 1st ink. Examples of the thermoplastic resin include natural rubber, polyisoprene, poly-1,2-butadiene, polyisobutene, polybutene, poly-2-heptyl-1,3-butadiene, poly-2-t-butyl-1,3- Polymers of (di) enes such as butadiene and poly-1,3-butadiene), polyethers such as polyoxyethylene, polyoxypropylene, polyvinyl ethyl ether, polyvinyl hexyl ether, polyvinyl butyl ether, polyvinyl acetate, polyvinyl propio Examples include polyvinyl esters such as nate, polyurethane, ethyl cellulose, polyvinyl chloride, polyacrylonitrile, polymethacrylonitrile, polysulfone, polysulfide, and phenoxy resin.

  And polyacrylic acid esters such as polyethyl acrylate, polybutyl acrylate, poly-2-ethylhexyl acrylate, poly-t-butyl acrylate, poly-3-ethoxypropyl acrylate), and polymethyl acrylate; Polyisopropyl methacrylate, polydodecyl methacrylate, polytetradecyl methacrylate, poly-n-propyl methacrylate, poly-3,3,5-trimethylcyclohexyl methacrylate, polyethyl methacrylate, poly-2-nitro-2-methylpropyl methacrylate, poly- Polymethacrylic acid esters such as 1,1-diethylpropyl methacrylate and polymethyl methacrylate may be used.

  Furthermore, thermoplastic polyester resins and thermoplastic polyamide resins can also be used.

The first ink contains a photoacid generator as a polymerization initiator. The photoacid generator can be selected from, for example, a sulfonium salt represented by the following chemical formula (2), a sulfonium salt represented by the following chemical formula (3), and an iodonium salt represented by the following chemical formula (4).

As shown in the above chemical formula, an onium salt in which a sulfonium cation or an iodonium cation forms a counter ion with an anion is used as a photoacid generator. Furthermore, an onium salt in which a phosphonium cation forms a counter ion with an anion can also be used as a photoacid generator. As the iodonium salt, a diaryl iodonium salt represented by the following general formula (5) may be used.

(In the general formula (5), R ⁷ and R ⁸ are a hydrogen atom or a substituent having 1 to 20 carbon atoms, provided that at least one of them is a hydrogen atom, a linear alkyl group having 1 to 20 carbon atoms, Or a branched alkyl group having 3 to 20 carbon atoms.)
Anions as counter ions are fluoroborate anion, hexafluoroantimonate anion, hexafluoroarsenate anion, trifluoromethanesulfonate anion, paratoluenesulfonate anion, paranitrotoluenesulfonate anion, halogen anion, sulfonate anion, carboxylic acid It can be selected from the group consisting of anions and sulfate anions.

  Further, for example, photoacids such as diazonium salts, quinonediazide compounds, organic halides, aromatic sulfonate compounds, bisulfone compounds, sulfonyl compounds, sulfonate compounds, sulfonium compounds, sulfamide compounds, iodonium compounds, sulfonyldiazomethane compounds, and mixtures thereof The generator can be used as a photocationic polymerization initiator.

Specific examples of the onium salt are shown below.

Examples of commercially available onium salt compounds include the following products manufactured by Midori Chemical Co., Ltd. MPI-103 (CAS.NO. [87709-41-9]), BDS-105 (CAS.NO. [145612-66-4]), MDS-203 (CAS.NO. [127855-15-5]) Pyrogallol tritosylate (CAS.NO. [20032-64-8]), DTS-102 (CAS.NO. [75482-18-7]), DTS-103 (CAS.NO. [71449-78-0]) , MDS-103 (CAS.NO. [127279-74-7]), MDS-105 (CAS.NO. [116808-67-4]), MDS-205 (CAS.NO. [81416-37-7]) ), BMS-105 (CAS.NO. [149934-68-9]), TMS-105 (CAS.NO. [127820-3] 8-6]), NB-101 (CAS.NO. [20444-09-1]), NB-201 (CAS.NO. [4450-68-4]), DNB-101 (CAS.NO. [114719). -51-6]), DNB-102 (CAS.NO. [131509-55-2]), DNB-103 (CAS.NO. [132898-35-2]), DNB-104 (CAS.NO. [ 132898-36-3]), DNB-105 (CAS.NO. [132898-37-4]), DAM-101 (CAS.NO. [1886-74-4]), DAM-102 (CAS.NO. [28343-24-0]), DAM-103 (CAS.NO. [14159-45-6]), DAM-104 (CAS.NO. [130290-80-1], CAS.NO. 130290-82-3]), DAM-201 (CAS.NO. [2832-50-1]), CMS-105, DAM-301 (CAS.No. [138529-81-4]), and EPI-105. (CAS. No. [135133-12-9]) and the like. ESACURE 1064 and ESACURE 1187 manufactured by Lamberti, CPI-100P manufactured by San Apro (CAS. No. [68156-13-8]), manufactured by Ciba Geigy IRGACURE250 and the like.

  Further, WPI-054 (CAS. No. [524678-29-3]), WPI-113 (CAS. No. [477602-76-9]), WPI-116 (CAS. [71786-70-4]), and WPI-170 (CAS. No. [61358-25-6]).

  Among the onium salts described above, sulfonium salts and iodonium salts are excellent in stability. However, due to its production process, it is usually inevitable that a monovalent salt (a salt of a monovalent cation and one anion) and a divalent or higher salt (eg a divalent cation and two anions). And a salt thereof. The content of the divalent or higher polyvalent salt in the mixture ranges up to about 75 mol%. In general, commercially available products are also in the state of such a mixture, and this tendency is particularly noticeable with sulfonium salts. It is known that when a polyvalent salt is contained in the ink, the photosensitive wavelength shifts to the long wavelength side, and generally the sensitivity becomes high. In order to secure such advantages, a salt having a valence of 2 or more may be intentionally mixed. For example, commercially available products such as Lamberti ESACURE-1064 and the like correspond to them.

  The polyvalent salt greatly affects the aggregation stability of particles and the like present in the ink. When particles or the like are contained in the ink, a dispersant is generally used to disperse the particles. Multivalent salts also have the disadvantage of causing a weak bond between the particles and the dispersant, resulting in the formation of gels or aggregates. When the first ink contains a filler as will be described later, usually, suppressing the presence of these polyvalent salts as much as possible leads to an improvement in the dispersion stability of the filler.

  The content of the polyvalent onium salt is usually preferably 20% by weight or less of the total amount of the onium salt. The content of the polyvalent onium salt is more preferably 5% by weight or less, and most preferably it is not contained.

  Among onium salt compounds, arylsulfonium fluorophosphate salts or aryliodonium fluorophosphate salts are particularly desirable. These have a great effect of suppressing aggregation of particles and the like, and are remarkably excellent in dispersion stability. Moreover, even if it is a monovalent onium salt, when the dispersant is insufficient, the terminal amine resin as the dispersant is gradually replaced with time. Therefore, it is desirable that the structure of the onium salt is not as close as possible to the bonding site between the surface of the particle or the like and the terminal of the dispersant. This is possible if the onium salt contains a relatively large substituent in the structure. Examples of the relatively large substituent include a benzene ring.

  When the benzene ring has an organic group having 20 or less carbon atoms, ionic adsorption on the surface of the particle or the like is further reduced due to steric hindrance. More preferably, 50 mol% or more of the benzene rings have an organic group having 4 to 20 carbon atoms. In this case, since decomposition of the decomposition product into the air during the photoreaction is suppressed, safety is improved. In addition, since the onium salt has high solubility in the cationically polymerizable compound, precipitation of the salt in the first ink can be suppressed.

  If a monovalent onium salt is used, the photosensitive wavelength shifts to the short wavelength side, so that the sensitivity tends to decrease. Such an inconvenience can be avoided when the structure includes an aromatic substituent having the VI element in the heterocyclic ring or an aromatic substituent having the VI element as a linking group. Specific examples of the VI element include sulfur and oxygen.

Furthermore, as shown in the following general formula (6) or (7), an onium salt containing a relatively large organic group has high dissolution stability and good dispersion stability.

Here, A ⁻ is a fluorophosphate anion, R ¹ , R ² , and R ³ are organic groups having 1 to 20 carbon atoms including a hydrogen atom, and R ⁴ is a divalent aromatic substituent or VI A divalent aromatic substituent containing an atom in the structure. At least one of R ¹ , R ² , and R ³ is a hydrogen atom, a linear alkyl group having 1 to 20 carbon atoms, or a branched alkyl group having 3 to 20 carbon atoms. At least one of R ¹ , R ² , and R ³ is preferably a linear alkyl group having 1 to 14 carbon atoms or a branched alkyl group having 3 to 5 carbon atoms.

Examples of the organic group having 1 to 20 carbon atoms that can be introduced as R ¹ , R ² , and R ³ include a methyl group, an ethyl group, a propyl group, a butyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, And alkyl groups such as decanyl group; alkyloxy groups having 20 to 20 carbon atoms such as methyloxy group, ethyloxy group, propyloxy group, butyloxy group, hexyloxy group, heptyloxy group, octyloxy group, nonyloxy group, and decanyloxy group A C3-C20 substituent having a polyethylene oxide skeleton obtained by dehydration condensation of ethylene glycol. At least one of R ^{1 to} R ³ has a linear alkyl group having 1 to 14 carbon atoms or a branched alkyl group having 3 to 5 carbon atoms.

Examples of the divalent aromatic substituent that can be introduced as R ⁴ include groups having phenylene such as phenylene and biphenylene; groups having a phenylene sulfide skeleton such as phenylene sulfide and phenylene disulfide; benzothiophenylene, thiophenylene, and biphenyl And groups having a thiophene skeleton such as a thiophenylene group; groups having a furan skeleton such as furanylene and benzofuranylene.

  In the first ink, the content of the photoacid generator can be set according to the acid generation efficiency, the amount of particles to be added, and the like. In one embodiment, the content of the photoacid generator is preferably 0.5 to 10% by weight of the cationic polymerizable compound. If the photoacid generator is contained within such a range, appropriate sensitivity can be ensured. In addition, the ink does not deteriorate over time or increase in viscosity over time.

  Since the amount of benzene generated decreases as the photoacid generator content decreases, it is desirable that the photoacid generator content be as low as possible. Also, depending on the type of photoacid generator, the optimal range of dormitory varies. When ESACURE1187 is used, the content is preferably 1 to 7% by weight, more preferably 3 to 5% by weight, based on the cationically polymerizable compound.

  A photosensitizer may be used together with the photoacid generator. Examples of the photosensitizer include acridine compounds, benzoflavins, perylenes, anthracenes, thioxanthone compounds, and laser dyes. Of these, compounds in which the hydrogen atom of dihydroxyanthracene is substituted with an organic group, thioxanthone derivatives, and the like are desirable because of their high effects.

As an anthracene compound, the anthracene diether compound represented, for example by following General formula (8) is mentioned.

  R is a monovalent organic group, and examples thereof include an alkyl group, an aryl group, a benzyl group, a hydroxyalkyl group, an alkoxyalkyl group, and a vinyl group.

  Specific examples of the alkyl group include methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, t-butyl group, n-pentyl group, and i-pentyl group. Etc. Examples of the aryl group include a phenyl group, a biphenyl group, an o-tolyl group, an m-tolyl group, and a p-tolyl group. Examples of the hydroxyalkyl group include a 2-hydroxyethyl group and a 3-hydroxypropyl group. Group, 2-methyl-2-hydroxyethyl group, 2-ethyl-2-hydroxyethyl group and the like. Examples of the alkoxyalkyl group include a 2-methoxyethyl group, a 3-methoxypropyl group, a 2-ethoxyethyl group, and a 3-ethoxypropyl group.

  Furthermore, an allyl group or a 2-methylallyl group may be introduced as R. Such a compound can be synthesized, for example, by the method shown in (J. Am. Chem. Soc., Vol. 124, No. 8 (2002) 1590).

  The RO group in the general formula (8) is preferably a group that polymerizes with an acid. Examples of such RO groups include vinyl ether groups, propenyl ether groups, epoxy groups, oxetane groups, and oxolane groups. When such a substituent is introduced as an RO group, the photosensitizer is also involved in the polymerization during the polymerization reaction by the polymerization initiator. As a result, the photosensitizer itself is also incorporated into the polymerization reaction product.

  In the case where the RO group is a group that dissociates with an acid or heat to generate an OH group, it is similarly involved in the polymerization reaction by the polymerization initiator and incorporated into the polymerization reaction product. Examples of such RO groups include tert-butyl group, tert-butoxycarbonyl group, acetal group, and silicone-containing group.

  That is, when the R group itself in the general formula (8) is polymerized, the photosensitizer becomes a part of the polymerization product. Alternatively, when an OH group generated by acid or heat in the photosensitizer is bonded to the photocationically polymerizable compound, the photosensitizer becomes part of the polymerization product. As a result, the degree of polymerization of the polymerization reaction can be further advanced, and the final curing performance (hardness) can be improved. By using such a first ink, the cured film obtained can be obtained. Durability can also be improved.

R ⁵ and R ⁶ in the general formula (8) may be the same or different and are each selected from the group consisting of a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, an alkylsulfonyl group, and an alkoxy group. When hydrogen atoms are introduced as R ⁵ and R ⁶ , they can be easily synthesized.

  Specific examples of the compound represented by the general formula (8) include 9,10-dimethoxyanthracene, 9,10-diethoxyanthracene, 9,10-dipropoxyanthracene, 9,10-dibutoxyanthracene, 2 Dialkoxyanthracenes such as ethyl-9,10-diethoxyanthracene (2,3-diethyl-9,10-diethoxyanthracene), 9,10-diphenoxyanthracene, 9,10-diallyloxyanthracene, 9,10-di (2-methylallyloxy) anthracene, 9,10-divinyloxyanthracene, 9,10-di (2-hydroxyethoxy) anthracene, 9,10-di (2-methoxyethoxy) anthracene, etc. Can be mentioned.

  Any compound exhibits a sufficient effect. However, in view of the cost of obtaining the compound itself or its synthesis raw material and the safety of the compound, 9,10-dibutoxyanthracene, 9,10-diethoxyanthracene, 9,10 -Dipropoxyanthracene and 9,10-divinyloxyanthracene are particularly preferred.

  The first ink can further contain a filler. The material of the filler is not particularly limited as long as the first ink layer can be cured and the shape can be maintained when the second ink is baked. The material of the filler can be selected from, for example, metals, metal compounds, glass, ceramics, and resins.

  The inclusion of the filler in the first ink is advantageous in the following points. On the cured film obtained by curing the first ink layer, a second ink layer containing particles is laminated, and the second ink layer is baked. The cured film is softened by this baking, but it does not soften more than necessary if a filler is contained. When the cured film is thermoplasticized, the particles in the second ink layer can be prevented from sinking into the cured film more than necessary. This can prevent the conductivity from decreasing.

  The filler contained in the first ink can be, for example, conductive particles or particles that exhibit conductivity by sintering. In this case, conductivity can be imparted to the first ink layer. Specifically, the material of the filler can be selected from metals, metal oxides, metal nitrides, metal carbides, metal complexes, and carbon. Examples of metals include copper, silver, gold, platinum, palladium, nickel, tin, cobalt, rhodium, iridium, iron, ruthenium, osmium, manganese, molybdenum, tungsten, niobium, tantalum, titanium, bismuth, antimony, lead, Or these alloys etc. are mentioned.

  When such conductive particles or particles that exhibit conductivity by sintering are used as a filler, the first ink layer needs to be patterned. This patterning will be described later.

  The shape of the filler is not particularly limited. For example, spherical or irregular particles can be used. In order to increase the conductivity, particles having a shape such as a nanorod shape, a needle shape, or a flake shape (flat) are effective. Here, the nanorod shape means a rod shape having an aspect ratio (rod length / rod diameter) greater than 1.0 and 20 or less.

  A second ink layer is formed on a cured film formed by curing the first ink layer, and the second ink layer contains predetermined particles. Depending on conditions, the particles in the second ink layer may sink into the cured film of the lower first ink. If the particles sink, the desired conductivity cannot be ensured. If the average particle diameter of the filler contained in the first ink is 500 nm or less, the sinking of particles in the second ink layer can be sufficiently reduced.

  When the first ink layer is formed by the ink jet method, the average particle size of the contained filler is preferably 300 nm or less. If the ink contains particles having an average particle diameter of 300 nm or less, the ink can be favorably ejected from the nozzles of the printer head. When the inkjet ink is used, the average particle size of the filler is more preferably 200 nm or less, and particularly preferably 180 nm or less.

  The particle diameter of the filler can be determined by the following method, for example. First, the ink sample is diluted to about 500 times in a solvent, the particle size is measured by the dynamic light scattering method for the diluted sample, and the cumulant average particle size is calculated by cumulant analysis. The value thus obtained is taken as the average particle diameter of the filler. In addition, although the value of an average particle diameter uses the value of a volume average normally, you may use z value (intensity average) by a dynamic light scattering method. Such a measurement can be performed using, for example, a Zetasizer manufactured by Malvern.

  The first ink is desired to have fluidity at normal temperature. The viscosity of the first ink can be appropriately selected according to the printing method. The viscosity of the first ink generally corresponds to the viscosity of the cationic polymerizable compound contained. As already described, when screen printing is applied, the viscosity of the first ink is preferably 0.1 Pa · sec to 500 Pa · sec. When ink jet printing is applied, the viscosity of the first ink is preferably in the range of 1 mPa · sec to 50 mPa · sec. The viscosity of the ink can be measured, for example, with a cone plate viscometer.

  The concentration of the filler contained in the first ink is not particularly limited as long as a predetermined range of viscosity can be secured. When carrying out photopolymerization of a cationically polymerizable compound, it is desirable that the concentration of the filler is 25% by weight or less. With such a concentration, light transmission is not hindered, so that the polymerization reaction of the cationic polymerizable compound can sufficiently proceed to be cured. Further, the first ink layer is desirably thin, but a desired effect can be obtained if it is 100 nm or more and 10 μm or less.

  The printing method of the first ink is not particularly limited, and the first ink can be applied on the insulating base material using any application device. The coating apparatus can be selected from, for example, a screen printing machine, an ink jet printer, a dispenser, a spin coater, a dip coating apparatus, a flexographic printing machine, a gravure printing machine, and the like.

  In the case where insulating particles are contained as a filler, the first ink layer is not necessarily patterned. Although it may be applied to the entire insulating substrate, patterning is advantageous in that the amount of ink used can be reduced. On the other hand, when conductive particles or particles that exhibit conductivity by sintering are contained in the first ink as a filler, the first ink layer is patterned.

  The pattern shape of the first ink layer can be the same shape as the pattern of the second ink layer. The pattern width of the first ink layer is not particularly limited as long as it is larger than the pattern width of the second ink. By printing in a pattern, the amount of the first ink used can be reduced. Further, it is possible to facilitate the patterning of the second ink by patterning the first ink, which will be described later.

  A cured film of a thermoplastic resin can be obtained by irradiating the first ink layer with light to polymerize the cationic polymerizable compound. Any light source can be used as long as it can be irradiated with ultraviolet rays. The light source can be selected from, for example, a high-pressure mercury lamp, a metal halide lamp, a xenon lamp, and an ultraviolet LED. A metal halide lamp is most desirable in terms of high illumination intensity.

When light irradiation is usually, 150~300mJ / cm ² as the accumulated light quantity, the peak irradiance is desirably made sensitive at about 1500~3000mW / cm ^2, but is not limited thereto. Light irradiation conditions such as integrated light quantity and peak illuminance may be appropriately selected according to the composition, film thickness, etc. of the first ink.

  By curing by photopolymerization, the first ink layer becomes a cured film of a thermoplastic resin. As shown in FIG. 2, a second ink layer 4 is formed on the cured film 3 formed on the insulating substrate 1.

  The second ink layer 4 is formed by the second ink. The second ink contains conductive particles or particles that exhibit conductivity by sintering, a dispersant for dispersing the particles in a solvent, and a dispersion medium. The material of the particles contained in the second ink can be selected from metal, metal oxide, metal nitride, metal carbide, metal complex, and carbon.

  The metal is preferably at least one metal selected from the group consisting of the fourth period, the fifth period, and the sixth period of the periodic table. Of these, at least one metal selected from Group 2 to 14 is more preferable, and Group 2, Group 8, Group 9, Group 10, Group 11, Group 12, Group 13, and Group 14 are more preferable. More preferred is at least one metal selected from the group.

  Specifically, copper, silver, gold, platinum, palladium, nickel, tin, cobalt, rhodium, iridium, iron, ruthenium, osmium, manganese, molybdenum, tungsten, niobium, tantalum, titanium, bismuth, antimony, lead, and Examples include materials selected from the group consisting of these alloys. Among these, copper, silver, gold, platinum, palladium, nickel, tin, cobalt, rhodium, and iridium are preferable. These may be used in combination or as an alloy.

  As the metal oxide, an oxide of titanium, copper, nickel, zinc, tin, indium or a combination thereof is preferable. The metal nitride is preferably a metal nitride selected from the group consisting of titanium, zirconium, niobium, tantalum, chromium, and vanadium. The metal carbide is preferably a metal carbide selected from the group consisting of tungsten, molybdenum, nickel, copper, cobalt, zirconium, vanadium, niobium, chromium, manganese, and iron.

  As the metal complex, for example, copper, silver, gold, platinum, palladium, nickel, tin, cobalt, rhodium, iridium, or a complex of these alloys is used.

  The shape of the particles is not particularly limited, and may be either spherical or indeterminate. In order to increase the conductivity of the obtained pattern, it is preferable to use particles having a shape such as a nanorod shape, a needle shape, or a flake shape. This is because the contact area between the particles increases in such a shape.

  The average particle diameter of the particles contained in the second ink is desirably 100 nm or less. The average particle diameter of the particles can be obtained by the same method as in the case of the filler contained in the first ink. The second ink containing particles having an average particle diameter of 100 nm or less can be fired at an appropriate temperature. When the average particle diameter of the particles is as small as 60 nm or less, the firing temperature can be made sufficiently low.

  However, if the average particle size of the particles contained in the second ink is too small, metal oxidation and particle aggregation tend to occur. By blending more protective dispersant, such inconvenience can be prevented, but in that case, the firing temperature increases. In order to bake in an appropriate temperature range, it is desirable that the average particle diameter of the particles contained in the second ink is 5 nm or more. In particular, in the case of a metal that is easily oxidized, such as copper, the average particle diameter is preferably 20 nm or more.

  As the particles contained in the second ink, particles having a larger particle diameter may be used together with the particles having the average particle diameter described above. The particle size of the large particle is not particularly limited, but the average particle size is desirably 5 μm or less. Particles having an average particle size of up to 5 μm can be favorably dispersed in the ink.

  However, when the second ink is printed by the inkjet method, it is desirable that the average particle size of the large particle size be 300 nm or less. As in the case of the first ink, if the ink contains particles having an average particle diameter of 300 nm or less, the ink can be favorably discharged from the nozzles of the printer head. When the inkjet ink is used, the average particle size of the particles contained in the second ink is more preferably 200 nm or less, and particularly preferably 180 nm or less.

  The second ink can be prepared by dispersing the above-described particles in a dispersion medium together with a dispersant. The dispersion medium is not particularly limited as long as the above-described particles can be dispersed and can be printed. Any dispersion medium that can be removed after printing and does not affect the conductivity of the resulting pattern layer can be used.

  For example, an organic solvent or water that can be volatilized by heating can be used. The organic solvent may be selected from the group consisting of, for example, alcohol solvents, ketone solvents, amide solvents, ester solvents, ether solvents, saturated hydrocarbons, nonpolar organic solvents, and low polarity organic solvents. it can.

  As the alcohol solvent, for example, a monoalcohol solvent, a polyhydric alcohol solvent, a polyhydric alcohol partial ether solvent, or the like can be used.

  Examples of the monoalcohol solvent include methanol, ethanol, 1-propanol, isopropanol, 1-butanol, isobutanol, 2-butanol, t-butanol, 1-pentanol, isopentanol, 2-methylbutanol, 2- Pentanol, t-pentanol, 3-methoxybutanol, 1-hexanol, 2-methylpentanol, 2-hexanol, 2-ethylbutanol, 1-heptanol, 2-heptanol, 3-heptanol, 1-octanol, 2- Ethylhexanol, 2-octanol, 1-nonanol, 2,6-dimethyl-4-heptanol, 1-decanol, cyclohexanol, glycidol, benzyl alcohol, methylcyclohexanol, 2-methyl-1-butanol, 3-methyl-2 Butanol, 4-methyl-2-pentanol, terpineol, dihydro terpineol, and diacetone alcohol.

  Examples of the polyhydric alcohol solvent include ethylene glycol, propylene glycol, 1,3-butylene glycol, pentamethylene glycol, 1,2-pentanediol, hexylene glycol, 2,5-hexanediol, and 2,4-heptane. Diol, 2-ethylhexane-1,3-diol, diethylene glycol, dipropylene glycol, 1,2-hexanediol, 1,2-octanediol, trimethylene glycol, triethylene glycol, tripropylene glycol, tetraethylene glycol, diethylene glycol Examples include propylene glycol, 1,2-butylene glycol, 1,3-butylene glycol, 1,4-butylene glycol, and glycerol.

  Examples of the polyhydric alcohol partial ether solvent include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, ethylene glycol monohexyl ether, ethylene glycol monophenyl ether, ethylene glycol mono- 2-ethylbutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether, diethylene glycol monohexyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene Glycol monobutyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, and dipropylene glycol monopropyl ether.

  Examples of the ketone solvent include acetone, methyl ethyl ketone, methyl n-propyl ketone, methyl n-butyl ketone, diethyl ketone, methyl isobutyl ketone, methyl n-pentyl ketone, ethyl n-butyl ketone, and methyl n-hexyl. Ketone, diisobutyl ketone, cyclohexanone, 2-hexanone, 2-methylcyclohexanone, 2,4-pentanedione, acetonylacetone, acetophenone, acetylacetone, 2,4-hexanedione, 2,4-heptanedione, 3, 5-heptanedione, 2,4-octanedione, 3,5-octanedione, 2,4-nonanedione, 3,5-nonanedione, 5-methyl-2,4-hexanedione, 2,2,6,6- Tetramethyl-3,5-heptanedione, and , Like β- diketones such as 1,1,5,5,5- hexafluoro-2,4-heptanedione.

  Examples of the amide solvent include formamide, N-methylformamide, N, N-dimethylformamide, N-ethylformamide, N, N-diethylformamide, acetamide, N-methylacetamide, N, N-dimethylacetamide, N- Ethylacetamide, N, N-diethylacetamide, N-methylpropionamide, N-methylpyrrolidone, N-formylmorpholine, N-formylpiperidine, N-formylpyrrolidine, N-acetylmorpholine, N-acetylpiperidine, and N-acetyl Examples include pyrrolidine.

  Examples of ester solvents include diethyl carbonate, ethylene carbonate, propylene carbonate, diethyl carbonate, methyl acetate, ethyl acetate, γ-butyrolactone, γ-valerolactone, n-propyl acetate, isopropyl acetate, n-butyl acetate, and isobutyl acetate. Sec-butyl acetate, n-pentyl acetate, sec-pentyl acetate, 3-methoxybutyl acetate, methyl pentyl acetate, 2-ethylbutyl acetate, 2-ethylhexyl acetate, benzyl acetate, cyclohexyl acetate, methylcyclohexyl acetate, ethyl propionate, Examples include n-butyl propionate, isoamyl propionate, diethyl oxalate, di-n-butyl oxalate, methyl lactate, ethyl lactate, and n-butyl lactate.

  Examples of ether solvents include dipropyl ether, diisopropyl ether, dioxane, tetrahydrofuran, tetrahydropyran, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dipropyl ether, propylene glycol dimethyl ether, propylene glycol diethyl ether, propylene glycol dipropyl. Examples include ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, and diethylene glycol dipropyl ether.

  Examples of saturated hydrocarbons include hexane, heptane, octane, nonane, decane, undecane, dodecane, tridecane, tetradecane, pentadecane, and hexadecane.

Examples of the nonpolar organic solvent or the low polarity organic solvent include xylene, toluene, ethylbenzene, mesitylene, cyclohexane, and cyclooctane.
The above-mentioned dispersion media may be used alone or in combination of two or more.

  When the second ink is printed by the ink jet method, the dispersion medium used for the second ink has low volatility and is difficult to vaporize under normal pressure at room temperature in order to discharge well from the nozzle of the printer head. desired. Among the alcohols described above, ethanol, 1-propaneol, 1-butanol, 1-octanol, terpineol, dihydroterpineol, 2-methoxyethanol, 2-ethoxyethanol, 2-n-butoxyethanol, and diacetone alcohol preferable.

  Many of glycols are high viscosity compounds. In order to adjust the viscosity so that it can be ejected by inkjet, it is preferable to use one having a relatively low viscosity. Specific examples include ethylene glycol, diethylene glycol, propylene glycol, 1,4-butylene glycol, and dipropylene glycol.

  As the dispersant for dispersing the particles in the dispersion medium as described above, a polymer dispersant or a surfactant can be used. Polymer dispersants include amine polymer compounds such as polyvinylpyrrolidone and polyethyleneimine; hydrocarbon polymer compounds having carboxylic acid groups such as polyacrylic acid and carboxymethylcellulose; acrylamides such as polyacrylamide; It can be selected from the group consisting of ethylene oxide, starch, and gelatin. Copolymers of the aforementioned polymer compounds can also be used. The dispersants may be used alone or in combination of two or more.

  Examples of the water-soluble dispersant include polyvinyl pyrrolidone (molecular weight: 1000 to 500,000), polyethyleneimine (molecular weight: 100 to 100,000), carboxymethyl cellulose (degree of substitution of carboxymethyl group of hydroxyl cellulose Na salt of alkali cellulose: 0. 4 or more, molecular weight: 1000-100000), polyacrylamide (molecular weight: 100-6000000), polyvinyl alcohol (molecular weight: 1000-100,000), polyethylene glycol (molecular weight: 100-50000), polyethylene oxide (molecular weight: 50000-900000), Examples thereof include gelatin (average molecular weight: 61000-67000), water-soluble starch, and the like. In addition, the numerical value in parenthesis has shown the number average molecular weight of the high molecular compound in the case of water solubility. It can use suitably as a dispersing agent in these ranges.

  Examples of commercially available polymer dispersants include Solsperse 20000, Solsperse 24000, Solsperse 26000, Solsperse 27000, Solsperse 28000 (manufactured by Lubrizol); Dispersic 160, Dispersic 161, Dispersic 162, Dispersic 163, Dispersic 166 Dispersic 170, Dispersic 180, Dispersic 182, Dispersic 184, Dispersic 190 (manufactured by BYK Chemie); EFKA-46, EFKA-47, EFKA-48, EFKA-49 (manufactured by EFKA Chemical); Polymer 100 , Polymer 120, polymer 150, polymer 400, polymer 401, polymer 402, polymer 403, polymer 450, polymer 451 Polymer 452, Polymer 453 (manufactured by EFKA Chemical); Azisper PB711, Azisper PA111, Azisper PB811, Azisper PW911 (manufactured by Ajinomoto Co.); Florene DOPA-158, Floren DOPA-22, Floren DOPA-17, Floren TG-730W, Floren Examples thereof include G-700 and Floren TG-720W (manufactured by Kyoeisha Chemical Co., Ltd.).

As the surfactant, for example, any surfactant having an amino group —NH ₂ , a carboxyl group —COOH, a sulfo group —SO ₃ H, or a phosphono group —PO (OH) ₂ can be used.

  Content of a dispersing agent can be suitably selected according to the kind etc. For example, in the case of a polymer dispersant, 1 to 20% by weight of the particle is preferable, and 3 to 10% by weight is more preferable. In the case of a surfactant, the molar ratio of particles: surfactant is preferably in the range of 1: 0.8 to 1:50. The particle: surfactant is more preferably in a molar ratio range of 1: 1 to 1:20.

  The second ink is desired to have fluidity at normal temperature. The viscosity of the second ink can be appropriately selected according to the printing method. For example, when screen printing is applied, the viscosity of the second ink is preferably 0.1 Pa · sec to 500 Pa · sec. When inkjet printing is applied, the viscosity of the second ink is preferably in the range of 1 mPa · sec to 50 mPa · sec. The viscosity of the ink can be measured, for example, with a cone plate viscometer.

  The content of the particles contained in the second ink is not particularly limited as long as the viscosity and conductivity in a predetermined range can be ensured. If the conductive particles or particles that exhibit conductivity by sintering account for 10 to 80% by weight of the total amount of the second ink, desired conductivity can be exhibited and the particles do not settle. The content of particles is more preferably 20 to 70% by weight of the entire second ink.

  The film thickness of the coating film of the second ink is not particularly limited as long as desired properties such as conductivity can be expressed. If it is formed with a film thickness of at least 1 μm or more, sufficient conductivity can be obtained. On the other hand, in order to perform sufficient baking, it is desirable that the film thickness of the second ink layer be 50 μm or less. When a larger film thickness is required, the second ink layer can be laminated.

  The method for printing the second ink is not particularly limited as long as it is a method capable of pattern printing, and printing can be performed on the first ink layer using any coating device. The coating device can be selected from, for example, a screen printing machine, an ink jet printer, a dispenser, a flexographic printing machine, a gravure printing machine, a micro contact printing machine, and the like.

  Among these, the ink jet printing method is preferable because a pattern can be printed without using a plate. Moreover, since it is non-contact printing, a base material is not damaged. Moreover, it is advantageous in that it can cope with the unevenness of the substrate.

  The second ink layer is formed by printing on a cured film obtained by curing the first ink. When the second ink layer is formed, in the first ink layer, a cationic polymerizable compound is polymerized by light irradiation to obtain a thermoplastic resin. Since the second ink is printed on the cured film of the thermoplastic resin, the first ink and the second ink do not mix with each other. However, the first ink is not necessarily completely cured.

  The ink containing the cationic polymerizable compound has a feature that the curing speed is slow. The ink layer after light irradiation is completely cured when heated. In the case of only light irradiation, the ink layer immediately after light irradiation is not sufficiently cured. Thereafter, there is a tendency that the curing gradually proceeds and completely cures.

  By laminating the second ink in a state where it is not completely cured, the adhesion between the first ink layer and the second ink layer is further enhanced. Even when the second ink is laminated after being completely cured, sufficient adhesion can be obtained by performing heat treatment as a subsequent step to plasticize the first ink.

  As described above, in the present embodiment, the second ink is printed on the cured coating film of the first ink. The second ink at this time is disposed on the first ink layer so as not to contact the substrate surface. When the first ink layer is patterned to form the second ink layer on the cured film pattern, the second ink layer is printed so as not to protrude from the end of the cured film pattern. This can be achieved by adjusting the contact angle of the second ink.

  The second ink does not have sufficient adhesion to the substrate. For this reason, when the second ink protrudes from the underlying cured film and is printed in direct contact with the substrate surface, the printed pattern is peeled off from this portion. When the cured film pattern is formed by printing the first ink layer in a pattern, it is desirable to form the second ink layer so as not to protrude from the end of the cured film pattern. If the second ink is printed out of the pattern edge, there is a possibility that a short circuit will occur at the portion that protrudes from the pattern.

  In order for the second ink layer not to protrude from the underlying cured film and to be patterned and printed on the cured film, the contact angle of the second ink with respect to the cured film must be sufficiently large. On the other hand, the first ink layer needs to exhibit a sufficiently large adhesion to the base material with the minimum necessary film thickness. For this reason, the first ink must have a sufficiently small contact angle with the substrate. This is possible if the contact angle of the first ink to the substrate is smaller than the contact angle of the second ink to the cured film.

  Specifically, the contact angle of the first ink with respect to the substrate is desirably 70 ° or less. If the contact angle is 70 ° or less, the adhesion between the cured film of the first ink layer and the substrate is sufficiently large. In practice, the contact angle of the first ink to the substrate must be smaller than the contact angle of the second ink to the cured film. For this reason, the range of an appropriate contact angle varies depending on the material of the base material, ink components, and the like.

  For example, since the contact angle of the second ink containing the aqueous dispersion medium is relatively large, the contact angle of the first ink with respect to the substrate may be 65 ° or less. When the second ink contains a hydrocarbon-based organic solvent such as xylene, the contact angle is relatively small. Therefore, the contact angle of the first ink with respect to the substrate is desirably 35 ° or less.

  Further, the contact angle of the first ink with respect to the substrate is desirably 10 ° or more. If the contact angle of the first ink is 10 ° or more, the flow of the liquid after application can be suppressed to form a fine pattern. In order to print a finer pattern, the contact angle of the first ink with respect to the base material is more preferably 20 ° or more.

  The larger the contact angle of the second ink with respect to the cured film formed by curing the first ink, the larger the film thickness of the second ink layer. The contact angle of the second ink varies depending on the type of the dispersion medium contained. When the aqueous dispersion medium is contained, the second contact angle with respect to the cured film is desirably 70 ° or more. On the other hand, when a hydrocarbon organic solvent is contained, the contact angle of the second ink with respect to the cured film is desirably larger than 35 °.

  If the contact angle has a predetermined size, the flow of ink after application is suppressed and fine patterning can be performed. Further, it becomes possible to print a pattern having a sufficient film thickness, and a circuit having sufficient conductivity can be obtained.

  The contact angle of ink can be measured by a method based on the JIS standard (JIS R3257). First, ink droplets are brought into contact with the substrate or the base coating film using a syringe. After 1 second, the contact angle with respect to the substrate or the base coating film is measured using, for example, a contact angle meter (DM-301) manufactured by Kyowa Interface Science Co.

  For example, the contact angles of the first ink and the second ink can be adjusted within a predetermined range by selecting a base material and adjusting the ink composition. Regarding the substrate, in addition to the selection of the substrate material, hydrophilic treatment or hydrophobic treatment by washing such as application of a treatment agent on the substrate surface, UV washing, plasma washing, and the like can be mentioned. With respect to the ink composition, selection of a dispersion medium, addition of a surfactant, adjustment of the type and amount of the surfactant, and the like can be mentioned.

  By adjusting the contact angle, the adhesion between the insulating substrate and the cured film of the first ink becomes sufficiently large, and this cured film can be used as a base for the second ink. When the contact angle of the first ink with respect to the substrate is larger than the above range, inconvenience occurs when the first ink layer is patterned. That is, due to the large contact angle, the surface of the first ink layer is not flat but convex, and the surface of the resulting cured film pattern has a convex surface. It is usually not easy to place the second ink layer on such a convex surface without protruding from the end of the cured film.

  Similarly, if the contact angle of the second ink with respect to the cured film is smaller than the above range, when the second ink is applied onto the cured film coating film, the second ink does not protrude from the end of the cured film pattern. It becomes difficult to place ink. Therefore, the second ink can be stacked on the cured film by adjusting the contact angle as described above.

  After the second ink is printed to form the second ink layer on the cured film, the second ink layer is baked. By firing the second ink layer, the particles contained in the ink are sintered, and sufficient conductivity can be imparted. The method for firing the second ink layer is not particularly limited, and for example, a method of heating with an oven is common.

  The second ink layer can be fired by heating in a vacuum, in an inert gas atmosphere such as nitrogen, or in a reducing gas atmosphere such as hydrogen or formic acid. Alternatively, the second ink layer may be baked by a method such as a method using microwave heating, a method using plasma, a reduction treatment with hydrogen radicals using a hot wire method, laser irradiation heating, or flash lamp irradiation.

  In the case where the insulating base material has flexibility, it is preferable to fire the second ink layer by a method such as flash lamp irradiation or laser irradiation. The material of the flexible substrate having flexibility is usually weak to heat. Therefore, it is desirable to avoid heating with a heater. The flash lamp irradiation heats the surface of the ink layer at a high speed, and the substrate can be processed with almost no increase in temperature. Moreover, it is preferable because irradiation can be performed simultaneously over the entire area of the substrate surface.

  When the second ink layer is fired by heating with a heater, it is required that not only the base material but also the cured film of the first ink can maintain heat resistance against the temperature during the firing. Even when the temperature of the entire base material is increased by the firing of the second ink layer, the base material is similarly required to have heat resistance.

  In order to obtain the adhesion of the second ink layer to the cured film of the first ink, it is effective to plasticize the cured film of the first ink by performing a heat treatment after printing the second ink. is there. The heat treatment can be performed separately from the above-described firing of the second ink layer, and may be performed either after or before firing. Normally, when the second ink layer is baked, the temperature of the first ink layer in contact with the second ink layer increases. For this reason, it is efficient to simultaneously plasticize the cured film of the first ink. The heating temperature at this time needs to reach a temperature at which the cured film of the first ink is thermoplasticized. The specific temperature may be appropriately selected according to the material of the first ink layer, the baking method, and the like.

  In particular, when the second ink layer is baked by a method such as flash lamp irradiation or laser irradiation that does not easily raise the temperature of the substrate, it is desirable to adjust the irradiation conditions as follows. Specifically, the irradiation conditions are such that a temperature at which the cured film of the first ink is thermoplasticized at the interface with the second ink layer.

  Usually, the temperature of the second ink is sufficiently higher than the temperature at which the first ink is thermoplasticized in order to sinter the particles by firing the second ink layer. It is presumed that the temperature at the interface between the second ink layer and the cured film of the first ink is higher than the temperature at which the cured film of the first ink is thermoplasticized. In order to obtain adhesion between the second ink layer and the cured film of the first ink, it is not always necessary to thermoplasticize the entire cured film of the first ink. If the first ink cured film is thermoplasticized at the interface with the second ink layer, sufficient adhesion can be secured.

  By performing a predetermined baking process, as shown in FIG. 3, the conductive pattern 5 as a sintered body of particles is formed on the insulating substrate 1 through the cured film 3 of the thermosetting resin. In the present specification, not only the laminate 6 of the cured film 3 and the conductive pattern 5 but also the insulating base material 1 is referred to as a printed matter.

  As described above, the conductive pattern forming method according to one embodiment makes it possible to form a conductive pattern having sufficient adhesion to the substrate by a printing method. The material of the base material used is not limited, and a conductive pattern having sufficient adhesion can be formed even on a flexible base material. That is, the metal nanoparticle ink can be printed on the flexible substrate.

  Compared with the primer coating treatment, the method of the present embodiment has a simple process and a reduced apparatus cost. This is because an apparatus and a process for coating are not necessary, and in some cases, it can be processed by an ink jet apparatus at the same time as wiring printing. According to the method of the present embodiment, it is possible to easily form a metal wiring having high adhesion to the substrate by a printing method.

  The method for forming the conductive pattern on the insulating base material has been described above, but the conductive pattern can also be formed on a metal base material. Examples of the metal substrate include stainless steel (SUS), copper, and aluminum.

  The first ink used is limited to the insulating property, and is printed on the metal substrate in a pattern shape wider than the pattern of the second ink. Except for forming the first ink pattern, the second ink can be printed by the same method as described above to form the conductive pattern.

Below, the specific example of formation of a conductive pattern is shown.
First, 10% by weight of an oxirane compound, 40% by weight of an oxetane compound, and 50% by weight of a vinyl ether compound were blended to prepare a cationically polymerizable compound contained in the first ink.

  As the oxirane compound, Celoxide 3000 (limonene dioxide, Daicel Chemical) was used, and as the oxetane compound, oxetane 211 (3-ethyl-3 {[(3-ethyloxetane-3-yl) methoxy] methyl} oxetane, Tojo Synthesis) was used. Moreover, ONB-DVE (hydroxymethyl-hydroxyoxa norbornanediol divinyl ether, Daicel Chemical) was used as the vinyl ether compound.

  A photoacid generator and a sensitizer were added to the cationic polymerizable compound to obtain a first ink (A). As the photoacid generator, ESACURE 1064 (LAMBERTI) was used, and its content was 7.5% by weight of the total ink. As the sensitizer, 9,10-dibutoxyanthracene (Kawasaki Kasei) was used, and its content was 0.4% by weight of the total ink.

  Further, first inks B, C, and D were obtained in the same manner as the first ink A described above except that particles and the like were added as follows. In addition, the addition amount of each particle | grain etc. is a ratio with respect to the whole ink.

(First Ink B) 10% by weight of silica particles having a particle diameter of 150 nm (first ink C) 20% by weight of silver particles (spherical) having a particle diameter of 40 nm (first ink D) Flaky silver particles Table 1 below summarizes the particles and the like contained in the first inks A to D.

  As the second ink, an ink (manufactured by Daiken Chemical) in which silver particles (average particle diameter of about 8 to 10 nm) are dispersed in a dispersion medium was prepared. The dispersion medium is undecane, and the content of silver particles in the ink is 50% by weight.

Example 1
A glass substrate was prepared as an insulating substrate, and surface treatment was performed using a UV ozone treatment machine. A first ink layer was formed on the treated glass substrate using the first ink A described above. Specifically, the first ink A was applied onto a glass substrate using a bar coater to form an ink layer having a thickness of about 4 μm.

Using a metal halide lamp (Light Hammer 6, manufactured by Fusion), the first ink layer was irradiated with UV. The peak illuminance of the lamp was 1800 mW / cm ² and the cumulative amount of irradiation was 250 mJ / cm ² . The first ink layer after UV irradiation was further heated with a hot plate at 150 ° C. for 5 minutes to obtain a cured film.

  On the cured film, the second ink was printed by an inkjet method to form a second ink layer. The pattern was linear with a line width of 500 μm. Using an electric furnace, the second ink layer was baked at 300 ° C. for 60 minutes in an inert atmosphere to obtain a conductive pattern.

(Example 2)
A conductive pattern was obtained in the same manner as in Example 1 except that the second ink layer was cured by light irradiation. Specifically, irradiation was performed at a flash time of 1 ms at 20 J / cm ² using a flash lamp.

(Example 3)
A conductive pattern was obtained in the same manner as in Example 2 except that the substrate was changed to a polyimide film.

Example 4
A conductive pattern was obtained in the same manner as in Example 2 except that the substrate was changed to a PET film.

(Example 5)
A cured film pattern of the first ink was formed in the same manner as in Example 2 except that the first ink was applied by an inkjet method and a linear pattern having a line width of 1 mm was printed. A conductive pattern was obtained in the same manner as in Example 2 except that the second ink layer was formed on the cured film pattern with a pattern having a line width of 1 mm by an inkjet method.

  The cross-sectional shape of the obtained conductive pattern was a shape as shown in FIG.

(Example 6)
A conductive pattern was obtained in the same manner as in Example 2 except that only the UV irradiation was used for curing the first ink layer and heating was not performed.

(Example 7)
A conductive pattern was obtained in the same manner as in Example 2 except that the first ink B was used as the first ink.

(Example 8)
A conductive pattern was obtained in the same manner as in Example 2 except that the first ink C was used as the first ink.

Example 9
A conductive pattern was obtained in the same manner as in Example 2 except that the first ink D was used as the first ink.

About Examples 1-9, the formation conditions of a 1st ink layer and the baking method of a 2nd ink layer are put together in the following Table 2 with the used base material.

  In any of Examples 1 to 9, the contact angle of the first ink with respect to the substrate is smaller than the contact angle of the second ink with respect to the cured film of the first ink. It was confirmed by measurement with a goniometer (DM-301). In any case, the conductive pattern was formed on the cured film of the first ink so that the entire conductive pattern did not contact the substrate.

(Comparative Example 1)
A conductive pattern was obtained in the same manner as in Example 2 except that the first ink layer was not formed and the second ink layer was directly formed on the substrate.

(Comparative Example 2)
First ink E was prepared by blending TDVE (triethylene glycol divinyl ether, ISP Japan), a photoacid generator and a sensitizer. As the photoacid generator, ESACURE 1064 (LAMBERTI) was used, and its content was 7.5% by weight of the total ink. As the sensitizer, 9,10-dibutoxyanthracene (Kawasaki Kasei) was used, and its content was 0.4% by weight of the total ink. The cured film of the first ink E does not have thermoplasticity.

  A conductive pattern was obtained in the same manner as in Example 2 except that the first ink layer was formed using this ink E.

(Comparative Example 3)
A cured film pattern of the first ink was obtained in the same manner as in Example 2 except that the first ink was applied by an inkjet method and a linear pattern having a line width of 500 μm was printed. A conductive pattern was obtained in the same manner as in Example 2 except that the second ink layer was formed on the cured film pattern with a pattern having a line width of 1 mm by an inkjet method. The second ink layer was formed in direct contact with the substrate surface beyond the end of the cured film pattern.

(Comparative Example 4)
A cured film pattern of the first ink was applied in the same manner as in Example 2 except that the first ink was applied by an inkjet method on a glass substrate not subjected to surface treatment, and a linear pattern having a line width of 500 μm was printed. Formed.

  On the cured film, the second ink was printed by an inkjet method to form a second ink layer having a line width of 500 μm. The second ink used here is an ink in which 50% by weight of silver particles (average particle diameter of about 8 to 10 nm) is dispersed in butyl carbitol. A conductive pattern was obtained in the same manner as in Example 2 except that these points were changed.

  When measured with a contact angle meter (DM-301) manufactured by Kyowa Interface Science Co., Ltd., the contact angle of the first ink with respect to the substrate is 77 °, and the contact angle of the second ink with respect to the cured film of the first ink is It was confirmed to be 25 °.

About Comparative Examples 1-4, the formation conditions of a 1st ink layer and the baking method of a 2nd ink layer are put together in following Table 3 with the used base material.

  About the conductive pattern of an Example and a comparative example, adhesiveness, pattern shape, and resistivity were evaluated. The adhesion was evaluated based on a cross-cut peel test (JIS K5600-5-6, ISO 2409). The criteria for determining adhesion are as follows.

○: JIS classification 1 or less in peel test: Peeling area is 5% or less ×: JIS classification 2 or more in peel test: Peeling area exceeds 5% The pattern shape was judged by the presence or absence of abnormality by observation using an optical microscope. . If no abnormality is confirmed, “◯” is indicated. If confirmed, “X” is indicated. Note that an abnormality means an abnormality of the shape such as a protrusion of a pattern.

The resistivity was measured by the 4-terminal method. The resistivity is acceptable if it is 10 μΩ / cm ² or less.

The obtained results are summarized in Table 4 and Table 5 below.

As shown in Table 4 above, all of the conductive patterns formed in Examples 1 to 9 have good adhesion to the base material, and no abnormality occurs in the pattern shape. The maximum resistivity of the pattern is 5.1 μΩ / cm ^2, which is practically acceptable. In particular, Examples 7 to 9 show that the low efficiency becomes smaller when the filler is contained in the first ink.

  On the other hand, as shown in Table 5, in the comparative example, a conductive pattern with good adhesion cannot be formed. It is shown in Comparative Example 1 that when the first ink is not used, the resistivity is remarkably increased in addition to the abnormality in the pattern shape.

  In Comparative Example 2, the cured film of the first ink was not thermoplastic, and in Comparative Example 3, a part of the second ink layer was formed in direct contact with the substrate. Due to these, the adhesion of the conductive pattern was lowered.

  In Comparative Example 4, the contact angle of the first ink with respect to the substrate is larger than the contact angle of the second ink with respect to the cured film of the first ink. This is presumed to be caused by the decrease in adhesion and the deterioration of the pattern shape. In addition, in Comparative Example 4, since the film thickness was also reduced, the pattern resistivity was out of the practical level.

DESCRIPTION OF SYMBOLS 1 ... Insulating base material; 2 ... 1st ink layer; 3 ... Cured film of thermoplastic resin 4 ... 2nd ink layer: 5 ... Conductive pattern; 6 ... Laminated body of cured film and conductive pattern.

Claims (13)

Forming a first ink layer on the insulating substrate with a first ink containing a cationically polymerizable compound and a photoacid generator;
On the first ink layer containing a thermoplastic resin obtained by irradiating the first ink layer with ultraviolet rays to polymerize the cationic polymerizable compound, conductive particles or sintered The second ink that contains particles exhibiting conductivity and an aqueous dispersion medium and does not mix with the first ink layer is printed in a predetermined pattern, and the whole is in direct contact with the insulating substrate. Obtaining a second ink layer so as not to
The second ink layer is baked by heating the insulating substrate including the second ink layer to obtain a conductive pattern as a sintered body of the particles, and the first ink which is not completely cured And fully curing the layer ,
A method for forming a conductive pattern, wherein a contact angle of the second ink with respect to the first ink layer which is not completely cured is 70 ° or more . Forming a first ink layer on the insulating substrate with a first ink containing a cationically polymerizable compound and a photoacid generator;
On the first ink layer containing a thermoplastic resin obtained by irradiating the first ink layer with ultraviolet rays to polymerize the cationic polymerizable compound, conductive particles or sintered The second ink containing particles exhibiting electrical conductivity and a hydrocarbon-based organic solvent and not mixed with the first ink layer is printed in a predetermined pattern, and the whole is applied to the insulating substrate. Obtaining a second ink layer so as not to be in direct contact;
The second ink layer is baked by heating the insulating substrate including the second ink layer to obtain a conductive pattern as a sintered body of the particles, and the first ink which is not completely cured And fully curing the layer ,
The method of forming a conductive pattern, wherein a contact angle of the second ink with respect to the first ink layer that is not completely cured is greater than 35 ° . Method of forming a conductive pattern according to claim 1 or 2, wherein the first ink is characterized by containing a filler. The method for forming a conductive pattern according to claim 3 , wherein the cured film is formed in a pattern. The method for forming a conductive pattern according to claim 4 , wherein the filler is conductive particles or particles that exhibit conductivity when sintered. 6. The method for forming a conductive pattern according to claim 5 , wherein the filler has a nanorod shape, a needle shape, or a flat shape. The method for forming a conductive pattern according to claim 3 or 4 , wherein the filler is an insulating particle. The printing of the second ink, the method of forming the conductive pattern according to any one of claims 1 to 7, characterized in that an ink jet method. The contact angle of the first ink to the insulating substrate, the conductive pattern according to any one of claims 1 to 8, characterized in that less than the contact angle of the second ink to the cured film Forming method. Method of forming a conductive pattern according to any one of claims 1 to 9, wherein the insulating substrate is a flexible substrate. The firing of the second ink layer, the method of forming the conductive pattern according to any one of claims 1 to 10, characterized in that is carried out by light or heat. The method for forming a conductive pattern according to claim 11 , wherein the baking of the second ink layer is performed by laser irradiation or flash lamp irradiation. A printed matter comprising the conductive pattern formed by the method according to any one of claims 1 to 12 , and a cured film of the thermoplastic resin interposed between the insulating base material and the conductive pattern.

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