CN113782252A - UV heating dual-curing conductive slurry and preparation method thereof - Google Patents
UV heating dual-curing conductive slurry and preparation method thereof Download PDFInfo
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- CN113782252A CN113782252A CN202111345158.9A CN202111345158A CN113782252A CN 113782252 A CN113782252 A CN 113782252A CN 202111345158 A CN202111345158 A CN 202111345158A CN 113782252 A CN113782252 A CN 113782252A
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
- H01B1/00—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors
- H01B1/20—Conductive material dispersed in non-conductive organic material
- H01B1/22—Conductive material dispersed in non-conductive organic material the conductive material comprising metals or alloys
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
- H01B13/00—Apparatus or processes specially adapted for manufacturing conductors or cables
Abstract
The invention discloses UV heating dual-curing conductive slurry and a preparation method thereof. The conductive paste comprises conductive powder, prepolymer resin, a photoinitiator, a reactive diluent monomer and an additive. The prepolymer resin has both acrylate units and blocked isocyanate units which can be deblocked at high temperatures, thus having both UV-curing and thermal-curing properties. The conductive paste has the advantages of high curing speed, good flexibility of a cured film, strong bonding force and high conductivity, can realize deep complete curing, and can be applied to flexible base materials such as PET, PEN, PEEK and the like.
Description
Technical Field
The invention belongs to the technical field of conductive paste, and relates to UV heating dual-curing conductive paste and a preparation method thereof.
Background
The conductive paste is prepared by dispersing conductive powder in a high polymer resin system, most of high polymer resins used in the conventional conductive paste are thermosetting resins, the comprehensive performance of the thermosetting resins is excellent, but the conventional conductive paste has the problem of low curing speed, and the curing time of the conductive paste into a state capable of being rolled is at least more than 5 minutes, so that the conductive paste cannot meet the requirements of rapid production (such as Roll-to-Roll process) of an industrial production line. In contrast, Ultraviolet (UV) curing has the advantages of fast curing speed, no Volatile Organic Compound (VOC) emission, environmental friendliness, and the like, and is a promising slurry curing method. However, when a single UV curing paste is used as the conductive paste, it is difficult to achieve deep full curing due to poor transparency and large printing thickness of the conductive paste.
Thus, there is a need in the art for a conductive paste that has a fast primary cure speed and can achieve deep full cure.
Disclosure of Invention
Aiming at the problems, the invention provides UV heating dual-curing conductive paste and a preparation method thereof. The invention synthesizes the polyurethane acrylate resin blocked by isocyanate and applies the resin to the conductive paste. The resin has both acrylate units and blocked isocyanate units which can be deblocked at high temperatures: the acrylate unit contains carbon-carbon double bonds and can be rapidly cured by UV; the blocked isocyanate units release reactive isocyanate groups upon heating to react with the hydroxyl-containing acrylate monomers in the paste, and the paste also has thermosetting properties. The conductive paste has the characteristics of dual curing, high initial curing speed and high conductivity, and can realize deep complete curing under the conditions of poor transparency and large printing thickness of the conductive paste. Meanwhile, the main structure of the prepolymer resin is polyurethane acrylate, so that the slurry cured film has good flexibility and strong bonding force, can be applied to flexible base materials such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyether ether ketone (PEEK) and the like, and can be used for Roll-to-Roll rapid production.
Specifically, the invention provides a conductive paste, which comprises the following components in percentage by mass: 50-90% of conductive powder, 5-45% of prepolymer resin, 0.2-4% of photoinitiator, 2-25% of reactive diluent monomer and 0.05-3% of additive; wherein the prepolymer resin is polyurethane acrylate resin containing blocked isocyanate groups, the blocked isocyanate groups can release isocyanate groups under heating, and the reactive diluent monomers comprise acrylate monomers containing hydroxyl groups and acrylate monomers containing no hydroxyl groups.
In one or more embodiments, the urethane acrylate resin having a blocked isocyanate group is obtained by blocking an isocyanate group in the urethane acrylate resin having an isocyanate group with a blocking agent.
In one or more embodiments, the blocking agent is selected from one or more of m-cresol, diethyl malonate, ethyl acetoacetate, epsilon-caprolactam, and ketoxime.
In one or more embodiments, the isocyanate group-containing urethane acrylate resin is formed by reacting a polyester polyol, a diisocyanate, and a hydroxyl group-containing acrylate monomer.
In one or more embodiments, the isocyanate group-containing urethane acrylate resin has one or more of the following characteristics:
the polyester polyol is selected from one or more of polyethylene adipate glycol, polypropylene adipate glycol, polybutylene adipate glycol, polyhexamethylene adipate glycol, polydiethylene adipate glycol, polytetramethylene adipate glycol, polycaprolactone butanediol glycol, polycaprolactone neopentyl glycol, polycaprolactone hexanediol, polyhexamethylene carbonate glycol, 1, 6-hexanediol polycarbonate, polybutylene carbonate glycol and 1, 4-butanediol-1, 6-hexanediol polycarbonate;
the weight average molecular weight of the polyester polyol is 1000-5000;
the diisocyanate is selected from one or more of toluene diisocyanate, diphenylmethane diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, naphthalene diisocyanate, p-phenylene diisocyanate, 1, 4-cyclohexane diisocyanate, phenylene diisocyanate, cyclohexane dimethylene diisocyanate, norbornane diisocyanate, dimethyl biphenyl diisocyanate, methylcyclohexyl diisocyanate and dimethyl diphenylmethane diisocyanate;
the acrylate monomer containing hydroxyl is selected from one or more of hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate and hydroxypropyl methacrylate;
the polyurethane acrylate resin containing isocyanate groups is prepared from the following components in a molar ratio of 1: (2-3): (0.5-2) a polyester polyol, a diisocyanate and a hydroxyl-containing acrylate monomer. In one or more embodiments, the conductive powder includes one or more selected from the group consisting of silver powder, copper powder, silver-coated nickel powder, silver-coated aluminum powder, and silver-coated glass powder.
In one or more embodiments, the conductive powder has a particle size of 50nm to 15 μm.
In one or more embodiments, the photoinitiator comprises one or more selected from the group consisting of 2,4, 6-trimethylbenzoyldiphenylphosphine oxide, 2-methyl-1- (4-methylthiophenyl) -2-morpholinyl-1-propanone, 2-isopropylthioxanthone, 1-hydroxy-cyclohexyl-phenyl-methanone, 2-hydroxy-2-methyl-1-phenyl-1-propanone, benzoin dimethyl ether, methyl o-benzoylbenzoate, 4-chlorobenzophenone, diphenylethanedione, 2-chlorothianthrone and 1-chloro-4-propoxythhianthrone.
In one or more embodiments, the hydroxyl-containing acrylate monomer as the reactive diluent monomer is selected from one or more of hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, pentaerythritol triacrylate, and dipentaerythritol pentaacrylate.
In one or more embodiments, the non-hydroxyl containing acrylate monomer as the reactive diluent monomer is selected from the group consisting of lauryl acrylate, 2-ethylhexyl acrylate, butyl acrylate, trimethylolpropane triacrylate, ethoxylated trimethylolpropane triacrylate, isoborneol acrylate, ethoxylated 1, 6-hexanediol diacrylate, tripropylene glycol diacrylate, dipropylene glycol diacrylate, one or more of propylene glycol diacrylate, neopentyl glycol diacrylate, propoxylated trimethylolpropane triacrylate, diethylene glycol diacrylate phthalate, tripropylene glycol diacrylate, ethylene glycol diacrylate, diethylene glycol diacrylate, 1, 6-hexanediol diacrylate, 1, 4-butanediol diacrylate, and pentaerythritol tetraacrylate.
In one or more embodiments, the reactive diluent monomer has a mass ratio of the hydroxyl-containing acrylate monomer to the non-hydroxyl-containing acrylate monomer of 2:1 to 1: 2.
In one or more embodiments, the additive includes one or more selected from the group consisting of an antioxidant, a dispersant, a thixotropic agent, and a coupling agent.
In one or more embodiments, the antioxidant comprises one or more selected from the group consisting of hydroquinone, p-hydroxyanisole, 2, 6-di-tert-butyl-4-methylphenol, and 2, 2' -methylenebis (4-methyl-6-tert-butylphenol);
in one or more embodiments, the dispersant includes one or more selected from the group consisting of Silok-7423, Silok-7421, Silok-7455H, Silok-7631, Silok-7096, Silok-7160, BYK-111, BYK-2155, BYK-2008, BYK-170, BYK-2025, BYK-220S, BYK-106, BYK-370, BYK-388, modesty D9850, modesty 983, modesty 904S 910, modesty 912, modesty 929, DARVANC-N, and belief 4803.
In one or more embodiments, the thixotropic agent comprises one or more selected from the group consisting of polyethylene wax, fumed silica, organobentonite, and castor oil.
In one or more embodiments, the coupling agent includes one or more selected from the group consisting of silane coupling agents, titanate coupling agents, and aluminate coupling agents.
The present invention also provides a method of preparing a conductive paste according to any of the embodiments herein, comprising the steps of:
(1) preparation of urethane acrylate resin containing isocyanate group: reacting polyester polyol, diisocyanate and a hydroxyl-containing acrylate monomer under the action of a catalyst to obtain isocyanate group-containing polyurethane acrylate resin;
(2) preparation of urethane acrylate resin containing blocked isocyanate groups: reacting the polyurethane acrylate resin containing the isocyanate group with a blocking agent to obtain polyurethane acrylate resin containing blocked isocyanate group;
(3) preparing conductive slurry: uniformly mixing conductive powder, polyurethane acrylate resin containing closed isocyanate groups, a photoinitiator, a reactive diluent monomer and an additive, and rolling to obtain the conductive paste.
In one or more embodiments, in step (1), the polyester polyol, diisocyanate, and hydroxyl-containing acrylate monomer are fed in a molar ratio of 1: (2-3): (0.5-2).
In one or more embodiments, in the step (1), the catalyst is used in an amount of 0.005 to 0.05mol with respect to 1mol of the polyester polyol.
In one or more embodiments, in step (1), the catalyst is selected from one or more of N, N-dimethylbenzylamine, 1, 4-dimethylpiperazine, N-methylmorpholine, N-ethylmorpholine, dibutyltin dilaurate, stannous octoate, dibutyltin diacetate, potassium isooctanoate, tin isooctanoate, bismuth isooctanoate, and tetrabutyl titanate.
In one or more embodiments, the reaction temperature of step (1) is 60 to 100 ℃ and the reaction time is 2 to 5 hours.
In one or more embodiments, in step (2), the molar ratio of the blocking agent added to the isocyanate groups contained in the isocyanate group-containing urethane acrylate resin is 1 or more.
In one or more embodiments, the reaction temperature of step (2) is 60 to 160 ℃ and the reaction time is 2 to 5 hours.
In one or more embodiments, in step (3), the rolling is performed until the fineness of the conductive paste is 15 μm or less.
The invention also provides a conductive film prepared from the conductive paste according to any one of the embodiments.
In one or more embodiments, the conductive film is prepared by subjecting the conductive paste to UV curing, heat curing, or UV + heat dual curing.
The invention also provides an electronic device comprising a conductive film according to any of the embodiments herein.
Detailed Description
To make the features and effects of the present invention comprehensible to those skilled in the art, general description and definitions are made below with reference to terms and expressions mentioned in the specification and claims. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.
The theory or mechanism described and disclosed herein, whether correct or incorrect, should not limit the scope of the present invention in any way, i.e., the present disclosure may be practiced without limitation to any particular theory or mechanism.
In this context, for the sake of brevity, not all possible combinations of features in the various embodiments or examples are described. Therefore, the respective features in the respective embodiments or examples may be arbitrarily combined as long as there is no contradiction between the combinations of the features, and all the possible combinations should be considered as the scope of the present specification.
All features defined herein as numerical ranges or percentage ranges, such as values, amounts, levels and concentrations, are for brevity and convenience only. Accordingly, the description of numerical ranges or percentage ranges should be considered to cover and specifically disclose all possible subranges and individual numerical values (including integers and fractions) within the range.
Herein, the sum of the percentages of all the components of the composition is equal to 100%.
Unless otherwise specified herein, "comprise," include, "" contain, "and the like, encompass the meanings of" consisting essentially of … … "and" consisting of … …, "i.e.," a comprises a "encompasses the meanings of" a comprises a and others, "" a consists essentially of "and" a consists of a. Herein, unless otherwise specified, "consisting essentially of … …" is understood to mean "consisting of … …% or more, preferably 90% or more, more preferably 95% or more".
The conductive paste is a paste formed by rolling conductive powder and a resin system. The resin system of a conventional thermally curable conductive paste generally includes a resin, a curing agent, a solvent, and additives. The resin system of the conductive paste comprises a prepolymer resin, a photoinitiator, a reactive diluent monomer and an additive, wherein the prepolymer resin simultaneously has an acrylate unit and a blocked isocyanate unit capable of being deblocked at high temperature, so that the resin system has the characteristics of UV curing and thermal curing: under the action of UV light, the acrylate unit in the prepolymer resin and the acrylate unit in the reactive diluent monomer can generate a crosslinking reaction of carbon-carbon double bonds; under heating, the blocked isocyanate groups in the prepolymer resin can release reactive isocyanates which can then react with the hydroxyl-containing acrylate monomers in the reactive diluent monomers. Therefore, the conductive paste disclosed by the invention has the advantages of high curing speed of UV curing, no VOC (volatile organic compound) emission, environmental friendliness and the like, can meet the requirement of rapid production (such as Roll-to-Roll process) of an industrial production line, can be applied to a transparent substrate, also has the advantage of thermocuring, can be applied to a substrate with a shadow region or poor transparency, and can realize deep complete curing when the printing thickness is larger.
Conductive powder
The conductive paste may include one or more conductive powders. The conductive powder suitable for the present invention includes, but is not limited to, one or more selected from the group consisting of silver powder, copper powder, silver-coated nickel powder, silver-coated aluminum powder, and silver-coated glass powder. In some embodiments, the conductive powder in the conductive paste of the present invention includes one or both selected from the group consisting of silver powder and silver-coated copper powder. The shape of the conductive powder can be nano-wire, flake, irregular particle, sphere, etc., for example, the silver powder can be spherical silver powder, flake silver powder, and the silver-coated copper powder can be spherical silver-coated copper powder. The particle size of the conductive powder is preferably 50nm to 15 μm, for example 200nm to 10 μm. The particle diameter of the spherical conductive powder, such as spherical silver powder and spherical silver-coated copper powder, can be 50 nm-1 μm, 200 nm-800 nm or 200 nm-500 nm. The flake-like conductive powder, for example, flake-like silver powder, may have a particle diameter (equivalent particle diameter) of 1 to 15 μm, 2 to 10 μm, 2 to 9 μm or 2 to 8 μm. In some embodiments, the conductive powder in the conductive paste of the present invention includes plate-like silver powder. Preferably, two or more conductive powders with different shapes and/or different particle sizes are used in combination to realize the optimal conductive connection. In a preferred embodiment, the conductive powder in the conductive paste of the present invention includes spherical silver powder and plate-like silver powder, and optionally may further include spherical silver-coated copper powder. In these embodiments, the mass ratio of the spherical silver powder and the plate-like silver powder may be 1: 10 to 2:1, e.g. 1: 5 to 2: 1. 1: 2.5 to 1:1. the mass ratio of the silver powder to the silver-coated copper powder can be 2:1 to 10: 1, e.g. 7: 1.5 to 7: 1.
the conductive paste of the present invention contains 50 to 90wt%, for example, 60wt%, 65wt%, 70wt%, 75wt%, 80wt%, and 85wt% of the conductive powder, based on the total mass of the conductive paste.
Prepolymer resins
The prepolymer resin in the conductive paste of the present invention is a urethane acrylate resin containing a blocked isocyanate group. In the present invention, the blocked isocyanate group means a group formed by reacting a blocking agent with an isocyanate group (-N = C = O). The blocked isocyanate groups can be deblocked under heating to release reactive isocyanate groups. The heating conditions are heating to a temperature higher than room temperature (25 ℃), for example, 120 ℃ or higher, 140 ℃ or higher, 150 ℃ or higher.
Blocking agents that may be used to block isocyanate groups include, but are not limited to, one or more selected from the group consisting of m-cresol, diethyl malonate, ethyl acetoacetate, epsilon-caprolactam, and ketoxime. Useful ketoximes include, but are not limited to, methyl ethyl ketoxime, dimethyl ketoxime, acetophenone ketoxime, methyl isobutyl ketoxime, cyclopentanone oxime, and cyclohexanone oxime. In some embodiments, the ketoxime is methyl ethyl ketoxime.
In the present invention, the prepolymer resin preferably does not contain an unblocked isocyanate group.
The urethane acrylate resin containing a blocked isocyanate group suitable for the present invention can be obtained by reacting an isocyanate group-containing urethane acrylate resin with a blocking agent. The isocyanate group-containing urethane acrylic resin is preferably obtained by reacting a polyester polyol, a diisocyanate and a hydroxyl group-containing acrylate monomer, that is, the isocyanate group-containing urethane acrylic resin preferably contains a structural unit derived from the polyester polyol, a structural unit derived from the diisocyanate and a structural unit derived from the hydroxyl group-containing acrylate monomer. In the invention, the polyester polyol plays roles in chain extension and bonding, and the flexibility and the bonding force of the conductive paste are ensured. The acrylate unit with the UV curing function can be connected to the prepolymer resin by using the acrylate monomer containing hydroxyl, so that the prepolymer resin has the UV curing function, and the rapid primary curing and forming of the conductive slurry are ensured.
Polyester polyols useful in the preparation of the isocyanate group-containing polyurethane acrylic resin include, but are not limited to, one or more selected from the group consisting of polyethylene adipate glycol, polypropylene adipate glycol, polybutylene adipate glycol, polyhexamethylene adipate glycol, polydiethylene adipate glycol, polyhexamethylene adipate glycol, polycaprolactone butylene glycol, polycaprolactone neopentyl glycol, polycaprolactone diethylene glycol, polycaprolactone hexanediol, polyhexamethylene carbonate glycol, poly-1, 6-hexanediol carbonate glycol, polybutylene carbonate glycol, poly-1, 4-butanediol-1, 6-hexanediol carbonate glycol. In some embodiments, the polyester polyol is selected from one or more of polyethylene adipate glycol, polybutylene adipate glycol, polyethylene adipate glycol, polycaprolactone glycol, poly-1, 6-hexanediol carbonate glycol, and poly-1, 4-butanediol-1, 6-hexanediol carbonate glycol. The polyester polyol preferably has a weight average molecular weight of 1000 to 5000, for example 2000, 3000, 4000, 5000. The molecular weight of the polyester polyol is too low, and the flexibility and the bonding force of a slurry cured film are insufficient; the molecular weight is too high, the viscosity of the prepolymer resin is too high, and the processability of the slurry is influenced; the molecular weight in the aforementioned range is advantageous for securing the flexibility, adhesion and slurry processability of the cured film.
Diisocyanates that can be used to prepare the isocyanate group-containing urethane acrylic resin include, but are not limited to, one or more selected from the group consisting of Toluene Diisocyanate (TDI), diphenylmethane diisocyanate (MDI), isophorone diisocyanate (IPDI), Hexamethylene Diisocyanate (HDI), dicyclohexylmethane diisocyanate, naphthalene diisocyanate, p-phenylene diisocyanate, 1, 4-cyclohexane diisocyanate, xylylene diisocyanate, cyclohexanedimethylene diisocyanate, norbornane diisocyanate, dimethylbiphenyl diisocyanate, methylcyclohexyl diisocyanate, and dimethyldiphenylmethane diisocyanate. In some embodiments, the diisocyanate is selected from one or more of toluene diisocyanate, diphenylmethane diisocyanate, isophorone diisocyanate, and hexamethylene diisocyanate.
The hydroxyl group-containing acrylate monomer that may be used to prepare the isocyanate group-containing urethane acrylic resin includes, but is not limited to, one or more selected from hydroxyethyl acrylate (HEA), hydroxyethyl methacrylate (HEMA), hydroxypropyl acrylate (HPA), hydroxypropyl methacrylate (HPMA).
The isocyanate group-containing urethane acrylate resin may be obtained by reacting a polyester polyol, a diisocyanate and a hydroxyl group-containing acrylate monomer in the presence of a catalyst. The feeding molar ratio of the polyester polyol, the diisocyanate and the hydroxyl-containing acrylate monomer is preferably 1: (2-3): (0.5-2), for example, 1: (2-2.5): (1-2) the structural unit derived from the polyester polyol is bonded to both ends of the structural unit derived from the diisocyanate in the produced urethane acrylate resin, and the urethane acrylate resin contains a free isocyanate group. Useful catalysts include, but are not limited to, one or more selected from the group consisting of N, N-dimethylbenzylamine, 1, 4-dimethylpiperazine, N-methylmorpholine, N-ethylmorpholine, dibutyltin dilaurate, stannous octoate, dibutyltin diacetate, potassium isooctanoate, tin isooctanoate, bismuth isooctanoate, tetrabutyl titanate. In some embodiments, the catalyst is selected from one or more of dibutyltin dilaurate, stannous octoate, dibutyltin diacetate, bismuth isooctanoate, N-ethyl morpholine, and tin isooctanoate. The catalyst may be used in an amount of 0.005 to 0.05mol, for example, 0.005 to 0.01mol, based on 1mol of the polyester polyol. The reaction temperature may be 60-100 deg.C, such as 75 deg.C, 80 deg.C, 85 deg.C, 90 deg.C. The reaction time can be 2-5 h, such as 3h, 3.5h and 4 h.
When the isocyanate group-containing urethane acrylate resin is blocked with a blocking agent, the molar ratio of the added blocking agent to the free isocyanate groups contained in the isocyanate group-containing urethane acrylate resin is 1 or more, preferably 1 or more, for example 1.05 or more, so that the free isocyanate groups are completely converted into blocked isocyanate groups. Assuming that the number of moles of diisocyanate used in the preparation of the isocyanate group-containing urethane acrylate resin is n1The mole number of the polyester polyol is n2The mole number of the acrylate monomer containing hydroxyl is n3The diisocyanate has 2-NCO groups, the polyester polyol has 2-OH groups, and the hydroxyl-containing acrylate monomer has 1-OH group, then in some embodiments, the number of moles n of the blocking agent added4Satisfies the following conditions: n is4≥(2n1-2n2-n3) Preferably n4>(2n1-2n2-n3) E.g. n4/(2n1-2n2-n3) Not less than 1.05. The temperature of the capping reaction may be 60 to 160 ℃, for example, 80 ℃, 90 ℃, 95 ℃, 100 ℃. The end-capping reaction time can be 2-5 h, such as 3h, 3.5h and 4 h.
In some embodiments, the prepolymer resin is prepared by:
(1) preparation of urethane acrylate resin containing isocyanate group: uniformly mixing 1mol of polyester polyol, 2-3 mol of diisocyanate, 0.5-2 mol of hydroxyl-containing acrylate monomer and 0.005-0.05 mol of catalyst, and reacting at 60-100 ℃ for 2-5 h to prepare polyurethane acrylate resin containing isocyanate groups;
(2) preparation of urethane acrylate resin containing blocked isocyanate groups: and uniformly mixing the polyurethane acrylate resin containing the isocyanate group with a blocking agent, and reacting for 2-5 h at 60-160 ℃ to obtain the polyurethane acrylate resin containing the blocked isocyanate group.
The content of the prepolymer resin in the conductive paste of the present invention is 5 to 45wt%, for example, 8wt%, 10wt%, 11wt%, 12wt%, 13wt%, 14wt%, 15wt%, 16.55wt%, 17wt%, 20wt%, 25wt%, based on the total mass of the conductive paste.
Photoinitiator
Photoinitiators suitable for use in the present invention include one or more selected from 2,4, 6-trimethylbenzoyldiphenylphosphine oxide, 2-methyl-1- (4-methylthiophenyl) -2-morpholinyl-1-propanone, 2-isopropylthioxanthone, 1-hydroxy-cyclohexyl-phenyl ketone, 2-hydroxy-2-methyl-1-phenyl-1-propanone, benzoin dimethyl ether, methyl o-benzoylbenzoate, 4-chlorobenzophenone, diphenylethanedione, 2-chlorothianthrone, 1-chloro-4-propoxythioxanthone. In some embodiments, the photoinitiator is selected from one or more of 2,4, 6-trimethylbenzoyldiphenylphosphine oxide, 2-methyl-1- (4-methylthiophenyl) -2-morpholinyl-1-propanone, 1-chloro-4-propoxythioanthrone, benzoin bismethyl ether, 2-hydroxy-2-methyl-1-phenyl-1-propanone, 2-isopropylthioxanthone, and 1-hydroxy-cyclohexyl-phenyl-methanone.
The content of the photoinitiator in the conductive paste is 0.2-4 wt%, for example, 0.5wt%, 0.6wt%, 0.7wt%, 1wt%, 1.2wt%, 1.5wt%, 2wt%, based on the total mass of the conductive paste.
Reactive diluent monomer
The reactive diluent monomer contained in the conductive paste of the present invention includes an acrylate monomer, and preferably includes at least one hydroxyl group-containing acrylate monomer and at least one non-hydroxyl group-containing acrylate monomer. The invention finds that the use of two acrylate monomers, namely, hydroxyl-containing acrylate monomer and hydroxyl-free acrylate monomer, is beneficial to improving the conductivity and the adhesive force of the conductive film made of the conductive paste.
Herein, the acrylate monomer refers to a compound containing a double bond and an ester bond formed by reacting an acrylate or methacrylate with an alcohol.
Hydroxyl-containing acrylate monomers that may be used as reactive diluent monomers include, but are not limited to, one or more selected from the group consisting of hydroxyethyl acrylate (HEA), hydroxyethyl methacrylate (HEMA), hydroxypropyl acrylate (HPA), hydroxypropyl methacrylate (HPMA), pentaerythritol triacrylate, dipentaerythritol pentaacrylate. In some embodiments, the hydroxyl-containing acrylate monomer as the reactive diluent monomer is selected from one or more of hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate, and pentaerythritol triacrylate.
Non-hydroxyl containing acrylate monomers useful as reactive diluent monomers include, but are not limited to, those selected from the group consisting of lauryl acrylate, 2-ethylhexyl acrylate, butyl acrylate, trimethylolpropane triacrylate (TMPTA), ethoxylated trimethylolpropane triacrylate (EO-TMPTA), isobornyl acrylate (IBOA), ethoxylated 1, 6-hexanediol diacrylate (EO-HDDA), tripropylene glycol diacrylate (TPGDA), dipropylene glycol diacrylate (DPGDA), Propylene Glycol Diacrylate (PGDA), neopentyl glycol diacrylate (NPGDA), propoxylated trimethylolpropane triacrylate (PO-TMPTA), diethylene glycol diacrylate Phthalate (PDDA), tripropylene glycol diacrylate phthalate, Ethylene Glycol Diacrylate (EGDA), diethylene glycol diacrylate (gddea), 1, 6-hexanediol diacrylate (HDDA), 1, 4-butanediol diacrylate (BDDA) and pentaerythritol tetraacrylate. In some embodiments, the non-hydroxyl containing acrylate monomer as the reactive diluent monomer is selected from one or more of pentaerythritol tetraacrylate, isoborneol acrylate, trimethylolpropane triacrylate, lauryl acrylate, propylene glycol diacrylate, neopentyl glycol diacrylate, ethylene glycol diacrylate and 1, 4-butanediol diacrylate.
The conductive paste of the present invention contains the reactive diluent monomer in an amount of 2 to 25wt%, for example, 4wt%, 4.55wt%, 6.2wt%, 6.7wt%, 8wt%, 8.15wt%, 8.5wt%, 9wt%, 12wt%, 15wt%, 20wt%, based on the total mass of the conductive paste. In the reactive diluent monomer, the mass ratio of the hydroxyl group-containing acrylate monomer to the hydroxyl group-free acrylate monomer may be 2:1 to 1:2, for example, 2:1 to 1: 1.7.
Additive agent
The conductive paste of the present invention may contain an additive. Additives suitable for use in the present invention include, but are not limited to, one or more selected from the group consisting of antioxidants, dispersants, thixotropic agents, coupling agents.
The conductive paste of the present invention contains 0.05 to 3wt%, for example, 0.1wt%, 0.2wt%, 0.25wt%, 0.3wt%, 0.35wt%, 0.4wt%, 0.45wt%, 0.5wt%, 1wt% of an additive, based on the total mass of the conductive paste.
Antioxidants suitable for use in the present invention include, but are not limited to, one or more selected from the group consisting of hydroquinone, p-hydroxyanisole, 2, 6-di-tert-butyl-4-methylphenol, and 2, 2' -methylenebis (4-methyl-6-tert-butylphenol). When the conductive paste contains an antioxidant, the content of the antioxidant in the conductive paste of the present invention may be 0.005 to 1wt%, for example, 0.01wt%, 0.02wt%, 0.05wt%, 0.1wt%, 0.2wt%, 0.5wt%, based on the total mass of the conductive paste.
Dispersants suitable for use in the present invention include, but are not limited to, one or more selected from Silok-7423, Silok-7421, Silok-7455H, Silok-7631, Silok-7096, Silok-7160, BYK-111, BYK-2155, BYK-2008, BYK-170, BYK-2025, BYK-220S, BYK-106, BYK-370, BYK-388, moded D9850, moded 983, moded 904S, moded 910, moded 912, moded 929, vanc-N, and surprise 4803. When the conductive paste contains a dispersant, the content of the dispersant in the conductive paste of the present invention may be 0.005 to 1% by weight, for example, 0.01%, 0.02%, 0.05%, 0.1%, 0.15%, 0.2%, 0.5% by weight, based on the total mass of the conductive paste
Thixotropic agents suitable for use in the present invention include, but are not limited to, one or more selected from the group consisting of polyethylene wax, fumed silica, organobentonite, castor oil. The castor oil may be hydrogenated castor oil. When the conductive paste contains a dispersant, the content of the thixotropic agent in the conductive paste of the present invention may be 0.005 to 1% by weight, for example, 0.01%, 0.02%, 0.05%, 0.1%, 0.15%, 0.2%, 0.5% by weight, based on the total mass of the conductive paste.
Coupling agents suitable for use in the present invention include, but are not limited to, one or more selected from silane coupling agents, titanate coupling agents, aluminate coupling agents. In some embodiments, the coupling agent is a silane coupling agent. Examples of the silane coupling agent include KH-560, KH-570, KBM-603 and the like. When the conductive paste includes a dispersant, the content of the coupling agent in the conductive paste of the present invention may be 0.005 to 1wt%, for example, 0.01wt%, 0.02wt%, 0.05wt%, 0.1wt%, 0.15wt%, 0.2wt%, 0.5wt%, based on the total mass of the conductive paste.
Conductive paste and conductive film
The conductive paste of the present invention can be prepared by uniformly mixing the components of the conductive paste and then rolling, for example, using a three-roll mill, preferably to a fineness of 15 μm or less, for example, 10 μm or less. The components and contents of the components in the conductive paste of the present invention are as described in any of the foregoing embodiments.
In some embodiments, the conductive paste of the present invention comprises 50 to 90wt%, for example 70 to 85wt%, of a conductive powder, 5 to 45wt%, for example 8 to 17wt%, of a prepolymer resin, 0.2 to 4wt%, for example 0.5 to 1.5wt%, of a photoinitiator, 2 to 25wt%, for example 4 to 12wt%, of a reactive diluent monomer, and 0.05 to 3wt%, for example 0.2 to 0.5wt%, of an additive, wherein the reactive diluent monomer preferably comprises a hydroxyl group-containing acrylate monomer and a non-hydroxyl group-containing acrylate monomer in a mass ratio of 2:1 to 1: 2.
The invention includes cured films prepared from the conductive pastes of the invention. The cured film is a conductive film. The cured film can be prepared by printing the conductive paste on a substrate and curing the conductive paste. The cured film may be present on the substrate in the form of lines or patterns. In the present invention, the curing may include one or both of UV curing and thermal curing. In some embodiments, curing comprises UV curing. The UV curing time may be 30-60s, for example 45. + -.5 s. When UV curing is adopted, the conductive paste has the remarkable advantage of high primary curing and forming speed, and the UV curing enables a cured film to be formed and rolled, so that the conductive paste is convenient to store, transport and produce quickly in a production line. The cured film formed by UV curing the conductive paste can be used as a semi-finished product and can be thermally cured when needed. In some embodiments, curing comprises thermal curing. The temperature for thermal curing may be 150. + -. 20 ℃ for example 150. + -. 10 ℃. The time for thermal curing may be 5. + -.1 min, for example 5. + -. 0.5 min. The conductive paste of the present invention can be completely cured by only a thermal curing method. In a preferred embodiment, curing includes UV curing and thermal curing. The conductive paste has poor transparency due to the inclusion of the conductive powder, and it is difficult to achieve deep full curing only with UV when the printing thickness is large, and the inside of the cured film can be fully cured by thermal curing before use. Compared with the method only adopting thermal curing, the cured film obtained by adopting UV curing and thermal curing has better conductivity and bonding force. In some embodiments, the conductive paste of the present invention is UV cured prior to thermal curing. Suitable substrates for use in the present invention may be flexible substrates such as PEEK, PET, PEN, and the like.
The invention also includes electronic devices, such as touch screens, LEDs, solar cells, sensors, printed wiring boards, RFID, etc., comprising the conductive film. The electronic device of the present invention may comprise a substrate, preferably a flexible substrate, such as PEEK, PET, PEN, etc., and the conductive film of the present invention present on the substrate.
The invention has the following beneficial effects: the conductive paste has the characteristics of dual curing, high curing speed, good flexibility of a cured film, strong bonding force and high conductivity, can be applied to flexible transparent base materials such as PET, PEN, PEEK and the like, and can be used for Roll-to-Roll rapid production.
The present invention is described in detail below with reference to specific examples, which do not limit the scope of the present invention. The scope of the present invention is defined only by the appended claims, and any omissions, substitutions, and changes in the form of the embodiments disclosed herein that may be made by those skilled in the art are intended to be included within the scope of the present invention.
The following examples use instrumentation conventional in the art. The experimental procedures, in which specific conditions are not noted in the following examples, are generally carried out under conventional conditions or conditions recommended by the manufacturers. In the following examples, various starting materials were used, unless otherwise specified, in conventional commercial products, the specifications of which are those commonly used in the art. In the description of the present invention and the following examples, "%" represents weight percent, "parts" represents parts by weight, and proportions represent weight ratios, unless otherwise specified.
Example 1
Prepolymer resin R-001 Synthesis: (1) uniformly mixing 1mol of polyethylene glycol adipate glycol (with the weight-average molecular weight of 2000), 2mol of Toluene Diisocyanate (TDI), 1mol of hydroxyethyl acrylate (HEA) and 0.006mol of dibutyltin dilaurate, and reacting at 80 ℃ for 3 hours to obtain isocyanate group-terminated polyurethane acrylate resin; (2) and (2) adding 1.05mol of methyl ethyl ketoxime into the product obtained in the step (1), and reacting at 80 ℃ for 3h to obtain the urethane acrylate resin R-001 containing blocked isocyanate end groups.
Preparing slurry: weighing 70g of flake silver powder (2.0-10.0 mu m), 16.55g of prepolymer resin (R-001), 1.0g of photoinitiator (2, 4, 6-trimethylbenzoyl diphenylphosphine oxide), 5.0g of hydroxyethyl acrylate (HEA), 5.0g of pentaerythritol tetraacrylate, 2.0g of isoborneol acrylate (IBOA), 0.05g of antioxidant (hydroquinone), 0.05g of silane coupling agent (KH-560), 0.15g of dispersant (BYK-111) and 0.20g of thixotropic agent (hydrogenated castor oil), uniformly stirring, and preparing into slurry with the fineness of less than 10 mu m by a three-roll machine.
Example 2
Prepolymer resin R-002 Synthesis: (1) uniformly mixing 1mol of polybutylene adipate glycol (with the weight-average molecular weight of 3000), 2.2mol of diphenylmethane diisocyanate (MDI), 1.5mol of hydroxypropyl acrylate (HPA) and 0.007mol of stannous octoate, and reacting at 85 ℃ for 3h to obtain isocyanate group-terminated polyurethane acrylate resin; (2) and (2) adding 0.95mol of epsilon-caprolactam into the product obtained in the step (1), and reacting for 3 hours at 95 ℃ to obtain polyurethane acrylate resin R-002 containing blocked isocyanate end groups.
Preparing slurry: weighing 38g of spherical silver powder (with the particle size of 200-500 nm), 37g of flake silver powder (2.0-8.0 mu m), 15g of prepolymer resin (R-002), 1.2g of photoinitiator (2-methyl-1- (4-methylmercaptophenyl) -2-morpholinyl-1-acetone), 3.0g of hydroxyethyl acrylate (HEA), 1.0g of pentaerythritol triacrylate, 2.5g of trimethylolpropane triacrylate (TMPTA), 2.0g of lauryl acrylate, 0.05g of antioxidant (2, 6-di-tert-butyl-4-methylphenol), 0.05g of silane coupling agent (KH-560), 0.10g of dispersant (BYK-2008) and 0.10g of thixotropic agent (hydrogenated castor oil), uniformly stirring, and preparing the mixture into slurry with the fineness of less than 10 mu m by a three-roll mill.
Example 3
Prepolymer resin R-003 Synthesis: (1) uniformly mixing 1mol of polybutylene adipate glycol (with the weight-average molecular weight of 4000), 2.5mol of Hexamethylene Diisocyanate (HDI), 2mol of hydroxypropyl methacrylate (HPMA) and 0.008mol of dibutyltin diacetate, and reacting at 75 ℃ for 4 hours to obtain isocyanate group-terminated polyurethane acrylate resin; (2) and (2) adding 1.05mol of ethyl acetoacetate into the product obtained in the step (1), and reacting at 95 ℃ for 3.5h to obtain the urethane acrylate resin R-003 containing blocked isocyanate end groups.
Preparing slurry: weighing 30g of spherical silver powder (with the particle size of 200-500 nm), 50g of flake silver powder (2.0-8.0 mu m), 11g of prepolymer resin (R-003), 0.6g of photoinitiator (1-chloro-4-propoxythioanthrone), 3.0g of hydroxypropyl acrylate (HPA), 3.0g of trimethylolpropane triacrylate (TMPTA), 2.0g of isoborneol acrylate (IBOA), 0.1g of antioxidant (2, 2' -methylenebis (4-methyl-6-tert-butylphenol)), 0.05g of silane coupling agent (KBM-603), 0.10g of dispersing agent (Silok-7096) and 0.15g of thixotropic agent (hydrogenated castor oil), uniformly stirring, and preparing into slurry with the fineness of less than 10 mu m by a three-roll machine.
Example 4
Prepolymer resin R-004 Synthesis: (1) uniformly mixing 1mol of poly diethylene glycol adipate glycol (with the weight-average molecular weight of 3000), 2.3mol of isophorone diisocyanate (IPDI), 1.6mol of hydroxyethyl methacrylate (HEMA) and 0.01mol of bismuth isooctanoate, and reacting at 80 ℃ for 4 hours to obtain isocyanate group-terminated polyurethane acrylate resin; (2) and (2) adding 1.05mol of diethyl malonate into the product obtained in the step (1), and reacting at 90 ℃ for 4h to obtain the polyurethane acrylate resin R-004 containing blocked isocyanate end groups.
Preparing slurry: weighing 10g of spherical silver-coated copper powder (with the particle size of 200-800 nm), 30g of spherical silver powder (with the particle size of 200-800 nm), 40g of flake silver powder (2.0-10.0 mu m), 10g of prepolymer resin (R-004), 0.7g of photoinitiator (benzoin dimethyl ether), 3.0g of hydroxyethyl acrylate (HEA), 1.0g of pentaerythritol triacrylate, 3.0g of Propylene Glycol Diacrylate (PGDA), 2.0g of neopentyl glycol diacrylate (NPGDA), 0.05g of antioxidant (2, 6-di-tert-butyl-4-methyl phenol), 0.05g of silane coupling agent (KBM-603), 0.05g of dispersing agent (Silok-7455H) and 0.15g of thixotropic agent (organic bentonite), uniformly stirring, and preparing the slurry with the fineness of less than 10 mu m by a three-roll mill.
Example 5
Prepolymer resin R-005 Synthesis: (1) uniformly mixing 1mol of polybutylene adipate glycol (with the weight-average molecular weight of 5000), 2.1mol of isophorone diisocyanate (IPDI), 1.8mol of hydroxyethyl acrylate (HEA) and 0.006mol of dibutyltin dilaurate, and reacting at 85 ℃ for 3.5h to obtain isocyanate group-terminated polyurethane acrylate resin; (2) and (2) adding 0.5mol of methyl ethyl ketoxime into the product obtained in the step (1), and reacting at 80 ℃ for 4h to obtain the urethane acrylate resin R-005 containing blocked isocyanate end groups.
Preparing slurry: weighing 15g of spherical silver-coated copper powder (with the particle size of 200-800 nm), 20g of spherical silver powder (with the particle size of 200-800 nm), 50g of flake silver powder (with the particle size of 2.0-10.0 mu m), 8.0g of prepolymer resin (R-005), 0.5g of photoinitiator (2-hydroxy-2-methyl-1-phenyl-1-acetone), 3.0g of hydroxyethyl methacrylate (HEMA), 3.2g of isoborneol acrylate (IBOA), 0.05g of antioxidant (hydroquinone), 0.05g of silane coupling agent (KBM-603), 0.05g of dispersant (Silok-7423) and 0.15g of thixotropic agent (organic bentonite), uniformly stirring, and preparing into slurry with the fineness of less than 10 mu m by a three-roll machine.
Example 6
Prepolymer resin R-006 synthesis: (1) 1mol of 1, 6-hexanediol polycarbonate diol (with the weight average molecular weight of 3000), 2.5mol of diphenylmethane diisocyanate (MDI), 1.9mol of hydroxypropyl acrylate (HPA) and 0.008mol of N-ethyl morpholine are uniformly mixed and reacted for 3 hours at 85 ℃ to obtain isocyanate group-terminated polyurethane acrylate resin; (2) and (2) adding 1.2mol of m-cresol into the product obtained in the step (1), and reacting for 4h at 100 ℃ to obtain the urethane acrylate resin R-006 containing blocked isocyanate end groups.
Preparing slurry: weighing 25g of spherical silver powder (with the particle size of 200-800 nm), 55g of flake silver powder (with the particle size of 2.0-10.0 mu m), 12g of prepolymer resin (R-006), 1.0g of photoinitiator (2-isopropylthioxanthone), 2.0g of hydroxyethyl methacrylate (HEMA), 2.0g of pentaerythritol triacrylate, 2.0g of isoborneol acrylate (IBOA), 0.7g of trimethylolpropane triacrylate (TMPTA), 0.05g of antioxidant (2, 6-di-tert-butyl-4-methylphenol), 0.05g of silane coupling agent (KH-570), 0.10g of dispersant (BYK-388) and 0.10g of thixotropic agent (organic bentonite), uniformly stirring, and preparing the mixture into slurry with the fineness of less than 10 mu m by using a three-roll machine.
Example 7
Synthesis of prepolymer resin R-007: (1) 1mol of 1, 4-butanediol-1, 6-hexanediol polycarbonate diol (with the weight average molecular weight of 2000), 2.2mol of Toluene Diisocyanate (TDI), 1.4mol of hydroxypropyl acrylate (HPA) and 0.005mol of dibutyltin dilaurate are uniformly mixed and reacted for 4 hours at 80 ℃ to obtain isocyanate group-terminated polyurethane acrylate resin; (2) and (2) adding 1.1mol of methyl ethyl ketoxime into the product obtained in the step (1), and reacting for 4h at 100 ℃ to obtain urethane acrylate resin R-007 containing blocked isocyanate end groups.
Preparing slurry: weighing 30g of spherical silver powder (with the particle size of 200-800 nm), 50g of flake silver powder (2.0-10.0 microns), 14g of prepolymer resin (R-007), 1.2g of photoinitiator (benzoin dimethyl ether), 1.0g of hydroxypropyl acrylate (HPA), 2.0g of pentaerythritol triacrylate, 1.55g of Ethylene Glycol Diacrylate (EGDA), 0.05g of antioxidant (p-hydroxyanisole), 0.05g of silane coupling agent (KH-570), 0.05g of dispersant (BYK-370) and 0.10g of thixotropic agent (polyethylene wax), uniformly stirring, and preparing into slurry with the fineness of less than 10 microns by using a three-roll machine.
Example 8
Prepolymer resin R-008 Synthesis: (1) uniformly mixing 1mol of polycaprolactone butanediol diol (with the weight-average molecular weight of 3000), 2.5mol of Hexamethylene Diisocyanate (HDI), 2mol of hydroxypropyl methacrylate (HPMA) and 0.006mol of tin isooctanoate, and reacting at 90 ℃ for 4 hours to obtain isocyanate group-terminated polyurethane acrylate resin; (2) and (2) adding 1.1mol of ethyl acetoacetate into the product obtained in the step (1), and reacting at 90 ℃ for 4h to obtain the polyurethane acrylate resin R-008 containing blocked isocyanate end groups.
Preparing slurry: weighing 35g of spherical silver powder (with the particle size of 200-800 nm), 40g of flake silver powder (with the particle size of 2.0-9.0 microns), 15g of prepolymer resin (R-008), 1.5g of photoinitiator (1-hydroxy-cyclohexyl-phenyl ketone), 2.0g of hydroxyethyl acrylate (HEA), 3.0g of pentaerythritol triacrylate, 3.15g of 1, 4-butanediol diacrylate (BDDA), 0.05g of antioxidant (p-hydroxyanisole), 0.05g of silane coupling agent (KBM-603), 0.10g of dispersant (DARVANC-N) and 0.15g of thixotropic agent (polyethylene wax), uniformly stirring, and preparing into slurry with the fineness of less than 10 microns by using a three-roll machine.
Comparative example 1: preparation of prepolymer resins using low molecular weight polyester polyols
Prepolymer resin V-001 synthesis: (1) uniformly mixing 1mol of polyethylene glycol adipate glycol (with the weight-average molecular weight of 500), 2mol of Toluene Diisocyanate (TDI), 1mol of hydroxyethyl acrylate (HEA) and 0.006mol of dibutyltin dilaurate, and reacting at 80 ℃ for 3 hours to obtain isocyanate group-terminated polyurethane acrylate resin; (2) and (2) adding 1.05mol of methyl ethyl ketoxime into the product obtained in the step (1), and reacting at 80 ℃ for 3h to obtain the urethane acrylate resin V-001 containing blocked isocyanate end groups.
Preparing slurry: weighing 70g of flake silver powder (2.0-10.0 mu m), 16.55g of prepolymer resin (V-001), 1.0g of photoinitiator (2, 4, 6-trimethylbenzoyl diphenylphosphine oxide), 5.0g of hydroxyethyl acrylate (HEA), 5.0g of pentaerythritol tetraacrylate, 2.0g of isoborneol acrylate (IBOA), 0.05g of antioxidant (hydroquinone), 0.05g of silane coupling agent (KH-560), 0.15g of dispersant (BYK-111) and 0.20g of thixotropic agent (hydrogenated castor oil), uniformly stirring, and preparing into slurry with the fineness of less than 10 mu m by a three-roll machine.
Comparative example 2: acrylate monomer containing no hydroxyl group is added into the sizing agent
Prepolymer resin R-001 Synthesis: (1) uniformly mixing 1mol of polyethylene glycol adipate glycol (with the weight-average molecular weight of 2000), 2mol of Toluene Diisocyanate (TDI), 1mol of hydroxyethyl acrylate (HEA) and 0.006mol of dibutyltin dilaurate, and reacting at 80 ℃ for 3 hours to obtain isocyanate group-terminated polyurethane acrylate resin; (2) and (2) adding 1.05mol of methyl ethyl ketoxime into the product obtained in the step (1), and reacting at 80 ℃ for 3h to obtain the urethane acrylate resin R-001 containing blocked isocyanate end groups.
Preparing slurry: weighing 70g of flake silver powder (2.0-10.0 mu m), 16.55g of prepolymer resin (R-001), 1.0g of photoinitiator (2, 4, 6-trimethylbenzoyl diphenylphosphine oxide), 7.0g of pentaerythritol tetraacrylate, 5.0g of isoborneol acrylate (IBOA), 0.05g of antioxidant (hydroquinone), 0.05g of silane coupling agent (KH-560), 0.15g of dispersant (BYK-111) and 0.20g of thixotropic agent (hydrogenated castor oil), uniformly stirring, and preparing into slurry with the fineness of less than 10 mu m by a three-roll machine.
Test example
1. The following performance tests were performed on the conductive pastes of examples 1 to 8 and comparative examples 1 to 2:
(1) testing the viscosity of the conductive paste;
(2) and (3) printing the conductive paste on a PET (polyethylene terephthalate) film, wherein the printing thickness is 20 mu m, evaluating the printability, and if the printing is not sticky, has no bubbles, is flat in a printing film and has good leveling property, considering that the printability is good.
2. The conductive paste of examples 1-8 and comparative examples 1-2 was printed on a PET film with a printing thickness of 20 μm, preliminarily cured by UV light for 45 seconds to form a UV cured film that can be rolled, and then thermally cured at 150 ℃/5min to obtain a UV cured + heat-cured film, and the following performance tests were performed on the dual cured film:
(1) testing the resistivity of the conductive paste cured film;
(2) testing the peel strength (180 degree peel, test standard: GB 2792) of the cured film of the conductive paste on the PET film;
(3) testing the flexibility of the cured film of the conductive paste: the conductive paste cured film was bent 200 times, and the resistivity of the cured film after bending and the peel strength on the substrate were tested.
3. The conductive paste of example 1 was printed on a PET film to a print thickness of 20 μm, and thermally cured at 150 ℃/5min to obtain a thermally cured film, which was subjected to the following performance tests:
(1) testing the resistivity of the conductive paste cured film;
(2) testing the peel strength (180 degree peel, test standard: GB 2792) of the cured film of the conductive paste on the PET film;
(3) testing the flexibility of the cured film of the conductive paste: the conductive paste cured film was bent 200 times, and the resistivity of the cured film after bending and the peel strength on the substrate were tested.
The results of the above performance tests are shown in table 1. The conductive paste has the advantages of high curing speed, good flexibility of a cured film, strong adhesive force and high conductivity, is suitable for Roll-to-Roll processes, and is suitable for a paste system with poor transparency and larger printing thickness.
As can be seen from table 1, compared to comparative example 1 in which the polyester polyol having a weight average molecular weight of 500 is used to prepare the prepolymer resin, examples 1 to 8 in which the polyester polyol having a weight average molecular weight of 1000 to 5000 is used to prepare the prepolymer resin have a cured film cured with a higher peel strength and a better adhesive strength, and have a smaller change in resistivity and glass strength after 200 times of bending, and a better flexibility.
As can be seen from table 1, the cured films of examples 1 to 8, to which the diluents of both the acrylate monomers containing a hydroxyl group and not containing a hydroxyl group were added, had better conductivity and adhesion after curing than those of comparative example 2, to which no diluent of the acrylate monomer containing a hydroxyl group was added.
As can be seen from table 1, the cured film after dual curing using UV + heating has better conductivity and adhesion than that after curing using only heating.
TABLE 1
Claims (10)
1. An electroconductive paste, characterized in that the electroconductive paste comprises, in mass percent: 50-90% of conductive powder, 5-45% of prepolymer resin, 0.2-4% of photoinitiator, 2-25% of reactive diluent monomer and 0.05-3% of additive; the prepolymer resin is a polyurethane acrylate resin containing a blocked isocyanate group, wherein the blocked isocyanate group can release an isocyanate group under a heating condition, the polyurethane acrylate resin containing the blocked isocyanate group is obtained by blocking the isocyanate group in the polyurethane acrylate resin containing the isocyanate group by using a blocking agent, the polyurethane acrylate resin containing the isocyanate group is formed by reacting polyester polyol, diisocyanate and an acrylate monomer containing a hydroxyl group, and the reactive diluent monomer comprises an acrylate monomer containing the hydroxyl group and an acrylate monomer containing no hydroxyl group.
2. The conductive paste according to claim 1, wherein the blocking agent is selected from one or more of m-cresol, diethyl malonate, ethyl acetoacetate, epsilon-caprolactam and ketoxime.
3. The electroconductive paste according to claim 1, wherein said isocyanate group-containing urethane acrylate resin has one or more of the following characteristics:
the polyester polyol is selected from one or more of polyethylene adipate glycol, polypropylene adipate glycol, polybutylene adipate glycol, polyhexamethylene adipate glycol, polydiethylene adipate glycol, polytetramethylene adipate glycol, polycaprolactone butanediol glycol, polycaprolactone neopentyl glycol, polycaprolactone hexanediol, polyhexamethylene carbonate glycol, 1, 6-hexanediol polycarbonate, polybutylene carbonate glycol and 1, 4-butanediol-1, 6-hexanediol polycarbonate;
the weight average molecular weight of the polyester polyol is 1000-5000;
the diisocyanate is selected from one or more of toluene diisocyanate, diphenylmethane diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, naphthalene diisocyanate, p-phenylene diisocyanate, 1, 4-cyclohexane diisocyanate, phenylene diisocyanate, cyclohexane dimethylene diisocyanate, norbornane diisocyanate, dimethyl biphenyl diisocyanate, methylcyclohexyl diisocyanate and dimethyl diphenylmethane diisocyanate;
the acrylate monomer containing hydroxyl is selected from one or more of hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate and hydroxypropyl methacrylate;
the polyurethane acrylate resin containing isocyanate groups is prepared from the following components in a molar ratio of 1: (2-3): (0.5-2) a polyester polyol, a diisocyanate and a hydroxyl-containing acrylate monomer.
4. The electroconductive paste according to claim 1, wherein the electroconductive paste has one or more of the following characteristics:
the conductive powder comprises one or more of silver powder, copper powder, silver-coated nickel powder, silver-coated aluminum powder and silver-coated glass powder;
the particle size of the conductive powder is 50 nm-15 mu m;
the photoinitiator comprises one or more selected from 2,4, 6-trimethylbenzoyldiphenylphosphine oxide, 2-methyl-1- (4-methylthiophenyl) -2-morpholinyl-1-propanone, 2-isopropylthioxanthone, 1-hydroxy-cyclohexyl-phenyl ketone, 2-hydroxy-2-methyl-1-phenyl-1-propanone, benzoin dimethyl ether, methyl o-benzoylbenzoate, 4-chlorobenzophenone, diphenylethanedione, 2-chlorothianthrone and 1-chloro-4-propoxythioxanthone;
the hydroxyl-containing acrylate monomer as the reactive diluent monomer is selected from one or more of hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, pentaerythritol triacrylate and dipentaerythritol pentaacrylate;
the acrylate monomer without hydroxyl group as the reactive diluent monomer is selected from the group consisting of lauryl acrylate, 2-ethylhexyl acrylate, butyl acrylate, trimethylolpropane triacrylate, ethoxylated trimethylolpropane triacrylate, isobornyl acrylate, ethoxylated 1, 6-hexanediol diacrylate, tripropylene glycol diacrylate, dipropylene glycol diacrylate, one or more of propylene glycol diacrylate, neopentyl glycol diacrylate, propoxylated trimethylolpropane triacrylate, diethylene glycol diacrylate phthalate, tripropylene glycol diacrylate, ethylene glycol diacrylate, diethylene glycol diacrylate, 1, 6-hexanediol diacrylate, 1, 4-butanediol diacrylate, and pentaerythritol tetraacrylate;
in the reactive diluent monomer, the mass ratio of the acrylate monomer containing hydroxyl to the acrylate monomer containing no hydroxyl is 2:1 to 1: 2;
the additive comprises one or more selected from an antioxidant, a dispersant, a thixotropic agent and a coupling agent.
5. The electroconductive paste according to claim 4, wherein said electroconductive paste has one or more of the following characteristics:
the antioxidant comprises one or more selected from hydroquinone, p-hydroxyanisole, 2, 6-di-tert-butyl-4-methylphenol and 2, 2' -methylenebis (4-methyl-6-tert-butylphenol);
the dispersant comprises one or more selected from Silok-7423, Silok-7421, Silok-7455H, Silok-7631, Silok-7096, Silok-7160, BYK-111, BYK-2155, BYK-2008, BYK-170, BYK-2025, BYK-220S, BYK-106, BYK-370, BYK-388, a modesty D9850, a modesty 983, a modesty 904S, a modesty 910, a modesty 912, a modesty 929, a DARVANC-N and a belief 4803;
the thixotropic agent comprises one or more selected from polyethylene wax, fumed silica, organic bentonite and castor oil;
the coupling agent comprises one or more selected from silane coupling agents, titanate coupling agents and aluminate coupling agents.
6. A method of preparing the electroconductive paste according to any one of claims 1 to 5, characterized in that the method comprises the steps of:
(1) preparation of urethane acrylate resin containing isocyanate group: reacting polyester polyol, diisocyanate and hydroxyl-containing acrylate monomer in the presence of a catalyst to obtain isocyanate-group-containing polyurethane acrylate resin;
(2) preparation of urethane acrylate resin containing blocked isocyanate groups: reacting the polyurethane acrylate resin containing the isocyanate group with a blocking agent to obtain polyurethane acrylate resin containing blocked isocyanate group;
(3) preparing conductive slurry: uniformly mixing conductive powder, polyurethane acrylate resin containing closed isocyanate groups, a photoinitiator, a reactive diluent monomer and an additive, and rolling to obtain the conductive paste.
7. The method of claim 6, wherein the method steps are characterized by one or more of the following:
in the step (1), the feeding molar ratio of the polyester polyol, the diisocyanate and the hydroxyl-containing acrylate monomer is 1: (2-3): (0.5-2);
in the step (1), the amount of the catalyst is 0.005-0.05 mol relative to 1mol of polyester polyol;
in the step (1), the catalyst is selected from one or more of N, N-dimethylbenzylamine, 1, 4-dimethylpiperazine, N-methylmorpholine, N-ethylmorpholine, dibutyltin dilaurate, stannous octoate, dibutyltin diacetate, potassium isooctanoate, tin isooctanoate, bismuth isooctanoate and tetrabutyl titanate;
the reaction temperature of the step (1) is 60-100 ℃, and the reaction time is 2-5 h;
in the step (2), the molar ratio of the added blocking agent to the isocyanate group contained in the polyurethane acrylate resin containing the isocyanate group is more than or equal to 1;
the reaction temperature of the step (2) is 60-160 ℃, and the reaction time is 2-5 h;
in the step (3), rolling is carried out until the fineness of the conductive paste is less than or equal to 15 mu m.
8. A conductive film produced from the conductive paste according to any one of claims 1 to 5.
9. The conductive film according to claim 8, wherein the conductive film is prepared by UV curing, heat curing, or UV + heat dual curing the conductive paste.
10. An electronic device comprising the conductive film according to claim 8 or 9.
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