阅读说明：本技术 一种柔性耐高温导电浆料 (Flexible high-temperature-resistant conductive paste ) 是由 苏亚军 沈远征 赵科良 王大林 张嘉宁 殷美 袁志勇 刘琪瑾 于 2021-09-23 设计创作，主要内容包括：本发明公开了一种柔性耐高温导电浆料,其成分包含导电粉体、高耐热树脂、环氧树脂、固化剂、促进剂、增韧剂、溶剂、偶联剂和流变助剂,所述增韧剂包含由氨基硅油和环氧树脂反应得到的氨基硅油改性环氧树脂。本发明的导电浆料的固化膜具有良好的柔韧性,可适用于PEEK、PI等柔性基材,固化膜兼具优良的耐高温性。本发明的导电浆料可应用于对耐热要求高的领域,如汽车、高铁、航天、军工等。(The invention discloses a flexible high-temperature-resistant conductive paste which comprises conductive powder, high-temperature-resistant resin, epoxy resin, a curing agent, an accelerator, a toughening agent, a solvent, a coupling agent and a rheological aid, wherein the toughening agent comprises amino silicone oil modified epoxy resin obtained by reacting amino silicone oil with the epoxy resin. The cured film of the conductive paste has good flexibility, can be suitable for PEEK, PI and other flexible substrates, and has excellent high-temperature resistance. The conductive paste can be applied to the fields with high heat resistance requirements, such as automobiles, high-speed rails, aerospace, military industry and the like.)

1. An electroconductive paste, characterized in that the electroconductive paste comprises, in mass percent: 50-90% of conductive powder, 5-45% of high heat-resistant resin, 1-20% of epoxy resin, 0.1-20% of curing agent, 0.05-1% of accelerator, 0.5-3% of flexibilizer, 1-20% of solvent, 0.01-1% of coupling agent and 0.01-1% of rheological additive; the toughening agent comprises amino silicone oil modified epoxy resin obtained by reacting amino silicone oil with epoxy resin, and the glass transition temperature of the high heat-resistant resin is more than 150 ℃.

2. The electroconductive paste according to claim 1, wherein said amino silicone oil-modified epoxy resin has one or more of the following characteristics:

the amino silicone oil part in the amino silicone oil modified epoxy resin is from amino silicone oil with the viscosity of 500-70000 mPa & s at 25 ℃ of 10rpm and the amino content of 0.1-5.0 wt%;

the epoxy resin part in the amino silicone oil modified epoxy resin is from liquid epoxy resin;

in the amino silicone oil modified epoxy resin, the mass ratio of the amino silicone oil part to the epoxy resin part is 2-85: 100, respectively;

the amino silicone oil modified epoxy resin is obtained by reacting amino silicone oil and epoxy resin at 120-150 ℃.

3. The conductive paste of claim 2, wherein the liquid epoxy resin has one or more of the following characteristics:

the liquid epoxy resin is selected from one or more of bisphenol A epoxy resin, bisphenol F epoxy resin, hydrogenated bisphenol A epoxy resin, hydrogenated bisphenol F epoxy resin, alicyclic epoxy resin and novolac epoxy resin;

the viscosity of the liquid epoxy resin is 10-50000 mPa & s at 10rpm and 25 ℃;

the epoxy value of the liquid epoxy resin is 0.1-0.8.

4. The conductive paste according to claim 1, wherein the conductive powder 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 shape of the conductive powder comprises one or more of a nanowire, a sheet, an irregular particle and a sphere;

the particle size of the conductive powder is 50 nm-15 mu m.

5. The electroconductive paste according to claim 1, wherein the electroconductive paste has one or more of the following characteristics:

the high heat-resistant resin is selected from one or more of polyimide, polyetherimide, polyamide-imide and bismaleimide resin;

the epoxy resin comprises high-temperature-resistant epoxy resin, and the glass transition temperature of the cured high-temperature-resistant epoxy resin is more than 150 ℃;

the curing agent comprises an amine curing agent;

the accelerator comprises an imidazole curing accelerator;

the solvent comprises one or more selected from naphtha, dimethylformamide, dimethylacetamide, N-methyl-2-pyrrolidone, mixed dibasic acid ester, ethylene glycol ethyl ether acetate, ethylene glycol butyl ether acetate, diethylene glycol butyl ether acetate, dimethyl succinate, dimethyl glutarate, dipropylene glycol methyl ether, dipropylene glycol butyl ether, diacetone alcohol, 3-methoxy butyl acetate, 3-methoxy butyl propionate, propylene carbonate, butyl acetate and diethylene glycol diacetate;

the coupling agent comprises one or more selected from silane coupling agent, titanate coupling agent and aluminate coupling agent;

the rheological additive comprises one or more selected from a dispersing agent, a thixotropic agent and a leveling agent;

the conductive paste comprises 0.5-3% of the amino silicone oil modified epoxy resin by mass percentage based on the total mass of the conductive paste.

6. The electroconductive paste according to claim 5, wherein said electroconductive paste has one or more of the following characteristics:

the high-temperature-resistant epoxy resin is selected from one or more of polyfunctional epoxy resin, biphenyl epoxy resin, naphthalene epoxy resin, dicyclopentadiene phenol epoxy resin and polyimide modified epoxy resin;

the amine curing agent is selected from one or more of 4, 4-diaminodiphenyl sulfone, 3-diaminodiphenyl sulfone, diphenylmethane diamine and dicyandiamide;

the imidazole curing accelerator is selected from one or more of 2-methylimidazole, 1-methylimidazole, 2-ethyl-4-methylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 2-undecylimidazole, 2-phenylimidazole and 2-phenyl-4-methylimidazole;

the dispersant is selected from one or more 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, a pretty D9850, a pretty 983, a pretty 904S, a pretty 910, a pretty 912, a pretty 929, a DARVANC-N and a Xinyue 4803;

the thixotropic agent is selected from one or more of polyethylene wax, organic bentonite, castor oil, hydrogenated castor oil and fumed silica;

the leveling agent is selected from one or more of an organic silicon leveling agent, an organic fluorine leveling agent and an acrylate leveling agent;

the conductive paste comprises 0.5-3% of the amino silicone oil modified epoxy resin by mass percent based on the total mass of the conductive paste.

7. A conductive film produced by using the conductive paste according to any one of claims 1 to 6.

8. An electronic device comprising the conductive film of claim 7.

9. A toughening agent of conductive paste, which is characterized in that the toughening agent is the amino silicone oil modified epoxy resin of any one of claims 1 to 3.

10. Use of the amino silicone oil-modified epoxy resin according to any one of claims 1 to 3 for producing a conductive paste having improved flexibility of a cured film.

Technical Field

The invention belongs to the technical field of conductive paste, and particularly relates to flexible high-temperature-resistant conductive paste and a preparation method thereof.

Background

The conductive slurry is prepared by dispersing conductive powder in a high polymer resin system. The polymeric resin commonly used in conductive pastes is epoxy resin. Epoxy resin has many excellent properties, such as good corrosion resistance, low curing shrinkage and high bonding strength, and conductive paste using epoxy resin as a matrix has been widely used in electronic technology. However, epoxy resin has the disadvantages of high crosslinking density, brittle nature, easy cracking, insufficient flexibility and the like after being cured, so that the epoxy resin is difficult to be applied to the field of flexible electronics. At present, the commonly used method for improving the flexibility of the epoxy resin is to add a toughening agent such as rubber or perform softening treatment (such as long-chain polyether modification and long-chain fatty acid modification) on the epoxy resin, and both the two methods can cause the heat resistance of the conductive paste to be reduced, so that the conductive paste is difficult to be applied to the field with high requirement on the use temperature.

Therefore, there is a need in the art for a conductive paste that is flexible and resistant to high temperatures.

Disclosure of Invention

Aiming at the problems of poor flexibility and poor temperature resistance of the existing epoxy resin conductive paste, the invention provides the flexible high-temperature-resistant conductive paste which comprises conductive powder, high-heat-resistant resin, epoxy resin, a curing agent, an accelerator, a toughening agent, a solvent, a coupling agent and a rheological aid. According to the invention, the amino silicone oil modified epoxy resin is introduced into the conductive paste system to serve as a high-temperature-resistant toughening agent and a high-heat-resistant resin, so that the conductive paste is ensured to have both flexibility and heat resistance. The cured film of the conductive paste has good flexibility, can be suitable for PEEK, PI and other flexible substrates, and has excellent high-temperature resistance (the glass transition temperature is more than 160 ℃). The conductive paste can be applied to the fields with high heat resistance requirements, such as automobiles, high-speed rails, aerospace, military industry and the like.

Specifically, the invention provides a conductive paste, which comprises the following components in percentage by mass: 50-90% of conductive powder, 5-45% of high heat-resistant resin, 1-20% of epoxy resin, 0.1-20% of curing agent, 0.05-1% of accelerator, 0.5-3% of flexibilizer, 1-20% of solvent, 0.01-1% of coupling agent and 0.01-1% of rheological additive; the toughening agent comprises amino silicone oil modified epoxy resin obtained by reacting amino silicone oil with epoxy resin, and the glass transition temperature of the high heat-resistant resin is more than 150 ℃.

In one or more embodiments, the amino silicone oil portion of the amino silicone oil-modified epoxy resin is derived from an amino silicone oil having a viscosity of 500 to 70000mPa · s at 25 ℃ at 10rpm and an amino group content of 0.1 to 5.0 wt%.

In one or more embodiments, the epoxy resin portion of the amino silicone oil-modified epoxy resin is derived from a liquid type epoxy resin.

In one or more embodiments, in the amino silicone oil-modified epoxy resin, the mass ratio of the amino silicone oil portion to the epoxy resin portion is 2 to 85: 100.

in one or more embodiments, the amino silicone oil modified epoxy resin is obtained by reacting amino silicone oil with epoxy resin at 120-150 ℃.

In one or more embodiments, the liquid type epoxy resin is selected from one or more of bisphenol a epoxy resin, bisphenol F epoxy resin, hydrogenated bisphenol a epoxy resin, hydrogenated bisphenol F epoxy resin, cycloaliphatic epoxy resin, and novolac epoxy resin.

In one or more embodiments, the liquid type epoxy resin has a viscosity of 10 to 50000 mPas at 10rpm and 25 ℃.

In one or more embodiments, the liquid type epoxy resin has an epoxy value of 0.1 to 0.8.

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 shape of the conductive powder includes one or more of nanowires, flakes, irregular particles, and spheres.

In one or more embodiments, the conductive powder has a particle size of 50nm to 15 μm.

In one or more embodiments, the high heat resistant resin is selected from one or more of a polyimide, polyetherimide, polyamideimide, and bismaleimide resin.

In one or more embodiments, the epoxy resin comprises a high temperature resistant epoxy resin that has a glass transition temperature greater than 150 ℃ after curing.

In one or more embodiments, the curing agent comprises an amine curing agent.

In one or more embodiments, the accelerator comprises an imidazole-based cure accelerator.

In one or more embodiments, the solvent comprises one or more selected from the group consisting of naphtha, dimethylformamide, dimethylacetamide, N-methyl-2-pyrrolidone, mixed dibasic esters (DBE), ethylene glycol ethyl ether acetate, ethylene glycol butyl ether acetate, diethylene glycol butyl ether acetate, dimethyl succinate, dimethyl glutarate, dipropylene glycol methyl ether, dipropylene glycol butyl ether, diacetone alcohol, butyl 3-methoxyacetate, butyl 3-methoxypropionate, propylene carbonate, butyl acetate, diethylene glycol diacetate.

In one or more embodiments, the coupling agent comprises one or more selected from the group consisting of silane coupling agents, titanate coupling agents, and aluminate coupling agents.

In one or more embodiments, the rheology aid comprises one or more selected from the group consisting of a dispersant, a thixotropic agent, and a leveling agent.

In one or more embodiments, the electroconductive paste contains the amino silicone oil-modified epoxy resin in a mass percentage of 0.5 to 3% based on the total mass of the electroconductive paste.

In one or more embodiments, the high temperature resistant epoxy resin is selected from one or more of a multifunctional epoxy resin, a biphenyl type epoxy resin, a naphthalene type epoxy resin, a dicyclopentadiene phenol epoxy resin, and a polyimide modified epoxy resin.

In one or more embodiments, the amine curing agent is selected from one or more of 4, 4-diaminodiphenyl sulfone, 3-diaminodiphenyl sulfone, diphenylmethanediamine, and dicyandiamide.

In one or more embodiments, the imidazole-based cure accelerator is selected from one or more of 2-methylimidazole, 1-methylimidazole, 2-ethyl-4-methylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 2-undecanoimidazole, 2-phenylimidazole, and 2-phenyl-4-methylimidazole.

In one or more embodiments, the dispersant is selected from one or more 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, modesty 910, modesty 912, modesty 929, DARVANC-N, and shininess 4803.

In one or more embodiments, the thixotropic agent is selected from one or more of polyethylene wax, organobentonite, castor oil, hydrogenated castor oil, and fumed silica.

In one or more embodiments, the leveling agent is selected from one or more of an organosilicon leveling agent, an organic fluorine leveling agent, and an acrylate leveling agent.

In one or more embodiments, the electroconductive paste contains the amino silicone oil-modified epoxy resin in a mass percentage of 1 to 2% based on the total mass of the electroconductive paste.

The invention also provides a conductive film prepared by adopting the conductive paste provided by any embodiment of the invention.

The invention also provides an electronic device comprising a conductive film according to any of the embodiments herein.

In one or more embodiments, the electronic device is a touch screen, a Light Emitting Diode (LED), a solar cell, a sensor, a printed wiring board, or an electronic tag (RFID).

The invention also provides a toughening agent of the conductive paste, wherein the toughening agent is the amino silicone oil modified epoxy resin in any embodiment.

The invention also provides application of the amino silicone oil modified epoxy resin in any embodiment of the invention in preparing conductive paste with improved cured film flexibility.

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, wherein the resin system generally comprises a resin, a curing agent, a solvent and optional auxiliaries (such as an accelerator, a toughening agent, a coupling agent, a rheological aid and the like). The invention discloses a conductive paste, which is prepared by introducing amino silicone oil modified epoxy resin as a toughening agent into the conductive paste, so that the flexibility of a cured film of the conductive paste can be improved, and the excellent heat resistance of the cured film can be ensured.

Conductive powder

The conductive paste may include one or more conductive powders. Conductive powders suitable for use in the present invention include, but are not limited to, 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 comprises 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 can be 50 nm-1 μm, 200 nm-800 nm or 200 nm-500 nm. The particle diameter (i.e., equivalent particle diameter) of the flake-shaped conductive powder may be 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 comprises spherical silver powder and plate-like silver powder, and optionally further comprises 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, the mass ratio of the silver powder to the silver-coated copper powder can be 2: 1 to 10: 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.

Resin composition

The resin of the conductive paste of the present invention includes a high heat-resistant resin and an epoxy resin.

The invention improves the heat resistance of the conductive paste by introducing high heat-resistant resin into the resin system of the conductive paste. In the present invention, the high heat-resistant resin means a resin having a glass transition temperature of more than 150 ℃. Examples of the high heat-resistant resin include polyimide, polyetherimide, polyamideimide and bismaleimide resins. It is understood that herein, the high heat resistant resin does not include an epoxy resin. In some embodiments, the high heat resistant resin in the conductive paste of the present invention comprises one or two selected from the group consisting of polyetherimide and polyamideimide.

The conductive paste of the present invention contains 5 to 45wt% of the high heat-resistant resin, for example, 6wt%, 7wt%, 85wt%, 9.4wt%, 9.7wt%, 10wt%, 12wt%, 12.5wt%, 16wt%, 18wt%, 20wt%, based on the total mass of the conductive paste.

The epoxy resin suitable for the present invention may be an epoxy resin commonly used for conductive pastes. It is preferable to use a high temperature resistant epoxy resin to further improve the heat resistance of the conductive paste. In the invention, the high-temperature-resistant epoxy resin refers to an epoxy resin with the glass transition temperature of more than 150 ℃ after being cured. Examples of the high temperature resistant epoxy resin include polyfunctional epoxy resins, biphenyl type epoxy resins, naphthalene type epoxy resins, dicyclopentadiene phenol epoxy resins, and polyimide modified epoxy resins. The multifunctional epoxy resin suitable for use in the present invention may be, for example, an amino tetrafunctional epoxy resin. In some embodiments, the epoxy resin in the conductive paste of the present invention includes one or more selected from the group consisting of an amino tetrafunctional epoxy resin, a biphenyl type epoxy resin, a naphthalene type epoxy resin, and a polyimide modified epoxy resin.

The conductive paste of the present invention contains 1 to 20wt% of the epoxy resin, for example, 2wt%, 2.5wt%, 2.7wt%, 3.2wt%, 3.4wt%, 3.5wt%, 3.6wt%, 4.5wt%, 4.8wt%, 5wt%, 10wt%, based on the total mass of the conductive paste.

Curing agent

The curing agent suitable for use in the present invention may be an amine curing agent. Examples of the amine-based curing agent include 4, 4-diaminodiphenyl sulfone, 3-diaminodiphenyl sulfone, diphenylmethanediamine, and dicyandiamide. In some embodiments, the curing agent in the conductive paste of the present invention is selected from one or more of 4, 4-diaminodiphenyl sulfone, diphenylmethane diamine, and dicyandiamide.

The content of the curing agent in the conductive paste of the present invention is 0.1 to 20wt%, for example, 0.5wt%, 1wt%, 1.3wt%, 1.8wt%, 2wt%, 2.2wt%, 2.7wt%, 3wt%, 5wt%, 10wt%, based on the total mass of the conductive paste.

Solvent(s)

The solvent suitable for the present invention may be one or more selected from hydrocarbon solvents, ester solvents, ether solvents, alcohol solvents, ketone solvents and amide solvents, and for example, may include one or more selected from naphtha, dimethylformamide, dimethylacetamide, N-methyl-2-pyrrolidone, DBE, ethylene glycol ethyl ether acetate, ethylene glycol butyl ether acetate, diethylene glycol butyl ether acetate, dimethyl succinate, dimethyl glutarate, dipropylene glycol methyl ether, dipropylene glycol butyl ether, diacetone alcohol, butyl 3-methoxypropionate, propylene carbonate, butyl acetate, diethylene glycol diacetate. In some embodiments, the solvent in the conductive paste of the present invention comprises ethylene glycol butyl ether acetate and/or diethylene glycol butyl ether acetate.

The content of the solvent in the conductive paste of the present invention is 1 to 20wt%, for example, 2wt%, 2.5wt%, 3wt%, 4wt%, 4.6wt%, 5wt%, 10wt%, based on the total mass of the conductive paste.

Toughening agent

The invention finds that the amino silicone oil modified epoxy resin can be used as a toughening agent of the conductive paste, is used for improving the flexibility of a cured film of the conductive paste and ensures that the cured film has excellent heat resistance. Accordingly, the present invention includes an amino silicone oil-modified epoxy resin that can be used as a toughening agent for conductive pastes.

The amino silicone oil modified epoxy resin is prepared by the reaction of amino silicone oil and epoxy resin. The viscosity of the amino silicone oil used as a raw material of the amino silicone oil-modified epoxy resin of the present invention at 10rpm and 25 ℃ is preferably 500 to 70000 mPas, for example, 5000 mPas, 8000 mPas, 15000 mPas, 20000 mPas, 48000 mPas, 50000 mPas, 55000 mPas, 58000 mPas, and 65000 mPas. The amino silicone oil preferably has an amino group content of 0.1 to 5wt%, for example, 0.25wt%, 0.5wt%, 0.8wt%, 1wt%, 1.5wt%, 2.0wt%, 2.5wt%, 3wt%, 4 wt%. Controlling the viscosity and the amino group content of the amino silicone oil within the aforementioned ranges is advantageous for the prepared amino silicone oil-modified epoxy resin to exert the effects of improving toughness and maintaining heat resistance.

The epoxy resin as a raw material of the amino silicone oil-modified epoxy resin of the present invention is preferably a liquid type epoxy resin. The liquid type epoxy resin (also referred to as liquid epoxy resin) is an epoxy resin that is liquid at room temperature. The epoxy resin as a raw material of the amino silicone oil-modified epoxy resin of the present invention may be one or more selected from the group consisting of bisphenol a epoxy resin, bisphenol F epoxy resin, hydrogenated bisphenol a epoxy resin, hydrogenated bisphenol F epoxy resin, alicyclic epoxy resin and novolac epoxy resin. Examples of cycloaliphatic epoxy resins include cyclohexanedimethanol diglycidyl ether. The viscosity of the epoxy resin used as a raw material of the amino silicone oil-modified epoxy resin of the present invention is preferably 10 to 50000 mPas, for example, 50 mPas, 60 mPas, 1500 mPas, 2000 mPas, 2300 mPas, 2500 mPas, 3000 mPas, 3200 mPas, 20000 mPas, 25000 mPas at 10rpm and 25 ℃. The epoxy value of the epoxy resin as a raw material of the amino silicone oil-modified epoxy resin of the present invention is preferably 0.1 to 0.8, for example, 0.4, 0.44, 0.48, 0.5, 0.54, 0.56, 0.58, 0.59, 0.72, 0.75. The epoxy resin with the characteristics is favorable for the prepared amino silicone oil modified epoxy resin to play the roles of improving the toughness and keeping the heat resistance.

When the amino silicone oil modified epoxy resin is prepared, the weight ratio of the amino silicone oil to the epoxy resin is preferably 2-85: 100, e.g. 10: 100. 15: 100. 20: 100. 30: 100. 50: 100. 60: 100. 70: 100. 75: 100. 80: 100. controlling the weight ratio of the amino silicone oil to the epoxy resin within the aforementioned range is advantageous for the prepared amino silicone oil-modified epoxy resin to exert the effects of improving toughness and maintaining heat resistance.

It is understood that the amino silicone oil-modified epoxy resin of the present invention, which is obtained by reacting an amino silicone oil with an epoxy resin, can be regarded as being composed of an amino silicone oil portion and an epoxy resin portion, wherein the amino silicone oil portion is derived from the raw material amino silicone oil, and the epoxy resin portion is derived from the raw material epoxy resin.

The amino silicone oil modified epoxy resin can be prepared by the following method: the uniformly mixed amino silicone oil and the epoxy resin are reacted at 120-150 ℃ (for example, 130 ℃, 140 ℃, 145 ℃ and 148 ℃). The reaction at the temperature is beneficial to the prepared amino silicone oil modified epoxy resin to play the roles of improving the toughness and keeping the heat resistance. The amino silicone oil and the epoxy resin can be uniformly mixed by stirring, and the stirring time can be 2-3 h, such as 2.4h and 2.5 h. The reaction time at 120-150 ℃ is preferably 3-4 h, such as 3.5 h.

The content of the toughening agent in the conductive paste is 0.5-3 wt%, such as 1-3 wt%, 1-2.5 wt%, 1.2-2 wt%, 0.5wt%, 1wt%, 1.2wt%, 1.5wt%, 1.8wt%, 2wt%, 2.5wt%, 3wt%, based on the total mass of the conductive paste. The toughening agent in the conductive paste comprises the amino silicone oil modified epoxy resin, and optionally can also comprise other toughening agents commonly used in conductive pastes, such as natural rubber, butadiene rubber, acrylate rubber, carboxyl-terminated nitrile rubber, polyurethane rubber, hyperbranched polymer, core-shell rubber particles and the like. When the electroconductive paste further contains a toughening agent other than the amino silicone oil-modified epoxy resin, the mass of the amino silicone oil-modified epoxy resin is preferably 50% or more, for example, 60% or more, of the total mass of the toughening agent, which is advantageous for improving the toughness of the electroconductive paste cured film and ensuring heat resistance.

In a preferred embodiment, the content of the amino silicone oil-modified epoxy resin in the conductive paste of the present invention is 0.5 to 3wt%, for example, 1 to 3wt%, 1 to 2.5wt%, 1 to 2wt%, 1wt%, 1.2wt%, 1.5wt%, 1.8wt%, 2wt%, 2.5wt%, 3wt%, which is advantageous for improving the toughness of the cured film of the conductive paste and ensuring heat resistance.

Compared with other commonly used toughening agents (such as natural rubber, butadiene rubber, acrylate rubber, carboxyl-terminated nitrile rubber, polyurethane rubber, hyperbranched polymer, core-shell rubber particles and the like), the amino silicone oil modified epoxy resin has the advantage of high temperature resistance. Therefore, the invention comprises the application of the amino silicone oil modified epoxy resin in preparing the conductive paste or the conductive paste cured film, the application of the amino silicone oil modified epoxy resin in preparing the conductive paste with improved flexibility of the cured film, a method for improving the flexibility of the conductive paste cured film, a method for preparing the conductive paste with improved flexibility of the cured film and a method for preparing the conductive paste cured film with improved flexibility. The application or method may be, for example, adding the amino silicone oil-modified epoxy resin of the present invention to a conductive paste, or further using the conductive paste to prepare a cured film. The amino silicone oil modified epoxy resin and the amount of the amino silicone oil modified epoxy resin in the conductive paste are the same as any embodiment of the invention.

Auxiliary agent

In addition to the toughening agent, the conductive paste of the present invention may also contain other adjuvants including, but not limited to, accelerators, coupling agents, rheology adjuvants, anti-settling agents, defoamers, antioxidants, and the like.

The accelerator is typically a cure accelerator. Accelerators suitable for use in the present invention may be imidazole based curing accelerators. Examples of the imidazole-based curing accelerator include 2-methylimidazole, 1-methylimidazole, 2-ethyl-4-methylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 2-undecanoimidazole, 2-phenylimidazole and 2-phenyl-4-methylimidazole. In some embodiments, the accelerator in the conductive paste of the present invention comprises one or more selected from the group consisting of 2-ethyl-4-methylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, and 2-phenyl-4-methylimidazole. When the conductive paste contains an accelerator, the content of the accelerator in the conductive paste of the present invention may be 0.05 to 1wt%, for example, 0.08wt%, 0.1wt%, 0.2wt%, 0.5wt%, based on the total mass of the conductive paste.

The coupling agent suitable for the present invention may be one or more selected from silane coupling agents, titanate coupling agents, aluminate coupling agents. In some embodiments, the coupling agent in the conductive paste of the present invention comprises a silane coupling agent. Examples of the silane coupling agent include KH-560, KH-570 and KBM-603. When the conductive paste includes a coupling agent, the content of the coupling agent in the conductive paste of the present invention may be 0.01 to 1wt%, for example, 0.02wt%, 0.05wt%, 0.1wt%, 0.5wt%, based on the total mass of the conductive paste.

The rheology assistant suitable for the present invention may include one or more selected from a dispersant, a thixotropic agent and a leveling agent. In some embodiments, the rheology aid in the conductive paste of the present invention includes a dispersant and/or a thixotropic agent. Examples of dispersants include 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, Demoded D9850, Demoded 983, Demoded 904S, Demoded 910, Demoded 912, Demoded 929, DARVANC-N and Bectone 4803. Examples of thixotropic agents include polyethylene wax, organobentonite, castor oil, hydrogenated castor oil, and fumed silica. When the conductive paste contains a rheological aid, the content of the rheological aid in the conductive paste of the present invention may be 0.01 to 1wt%, for example, 0.1wt%, 0.15wt%, 0.17wt%, 0.25wt%, 0.35wt%, 0.5wt%, based on the total mass of the conductive paste. When the rheology assistant comprises a dispersant and a thixotropic agent, the mass ratio of the dispersant to the thixotropic agent may be 1: 1 to 1: 3.

conductive paste and cured film

The conductive paste of the present invention can be obtained by uniformly mixing the components of the conductive paste and then rolling the mixture with a three-roll mill, preferably to a fineness of 15 μm or less, for example, 10 μm or less. The components and amounts of the components in the conductive paste may be as described in any of the embodiments above.

In some embodiments, the conductive paste of the present invention comprises 50 to 90wt%, preferably 60 to 90wt%, of conductive powder, 5 to 45wt%, preferably 5 to 20wt%, of high heat resistant resin, 1 to 20wt%, preferably 1 to 10wt%, of epoxy resin, 0.1 to 20wt%, preferably 0.5 to 5wt% of curing agent, 0.05 to 1wt%, preferably 0.05 to 0.5wt% of accelerator, 0.5 to 3wt%, preferably 1 to 3wt% of toughening agent, 1 to 20wt%, preferably 2 to 10wt% of solvent, 0.01 to 1wt%, preferably 0.02 to 0.5wt% of coupling agent, and 0.01 to 1wt%, preferably 0.1 to 0.5wt% of rheological aid; wherein the toughening agent comprises an amino silicone oil-modified epoxy resin as described herein. Preferably, the content of the amino silicone oil modified epoxy resin in the conductive paste is 0.5 to 3wt%, for example 1 to 2 wt%.

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, drying, and curing. The cured film may be present on the substrate in the form of a pattern. The curing temperature may be 160 ± 20 ℃. The curing time may be 1. + -. 0.5 h. The substrate may be a flexible substrate, such as a PI film and a PEEK film. The conductive paste is particularly suitable for flexible substrates such as PEEK films and PI films due to the improved flexibility. 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 a PI film or a PEEK film, and the conductive film of the present invention present on the substrate.

The invention has the following beneficial effects:

the invention discovers that the amino silicone oil modified epoxy resin can be used as a toughening agent to enable the conductive paste to have good flexibility and high temperature resistance, the glass transition temperature of a cured film prepared from the conductive paste can reach above 160 ℃, the absolute value of the resistivity change rate after 200 times of bending can be reduced to be not more than 20%, and the absolute value of the resistivity change rate after 200 times of bending can be reduced to be not more than 10%.

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:

synthesizing an organic silicon modified epoxy resin toughening agent: 20g of amino silicone oil (viscosity is 20000 mPas, amino content is 1.0%) and 100g of hydrogenated bisphenol A epoxy resin (viscosity is 2500 mPas, epoxy value is 0.54) are uniformly mixed, stirred for 2.5h, heated to 140 ℃ and reacted for 3.0h, thus obtaining the organic silicon modified epoxy resin toughening agent R-001.

Weighing 70g of flake silver powder (2.0-10.0 mu m), 16g of polyetherimide resin (SABIC), 4.8g of amino tetra-functional epoxy resin (SABIC, Inc., Jiannan Gshengde materials science and technology Co., Ltd.), 2.7g of curing agent (4, 4-diaminodiphenyl sulfone), 0.1g of accelerator (2-ethyl-4-methylimidazole), 2.0g of flexibilizer (R-001), 4.0g of diethylene glycol monobutyl ether acetate, 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 the slurry with the fineness of less than 10 mu m by a three-roll machine. The slurry is printed on a PI film substrate and is completely cured at 160 ℃/1 h.

Example 2:

synthesizing an organic silicon modified epoxy resin toughening agent: 30g of amino silicone oil (the viscosity is 15000 mPas, the amino content is 0.8%) and 100g of hydrogenated bisphenol F epoxy resin (the viscosity is 2000 mPas, the epoxy value is 0.56) are uniformly mixed, stirred for 2.0h, heated to 150 ℃ and reacted for 3.5h, and the organosilicon modified epoxy resin toughening agent R-002 is obtained.

38g of spherical silver powder (particle size of 200-500 nm), 37g of flake silver powder (2.0-8.0 mu m), 12.5g of polyetherimide resin (Sabic, Seiki basic Industrial Co., Ltd.), 3.5g of naphthalene type epoxy resin (HP-4700, Dajapan ink chemical industry Co., Ltd.), 2.2g of curing agent (4, 4-diaminodiphenyl sulfone), 0.1g of accelerator (2-ethyl-4-methylimidazole), 1.8g of flexibilizer (R-002), 4.6g of diethylene glycol monobutyl ether acetate, 0.05g of silane coupling agent (KH-560), 0.10g of dispersant (BYK-2008) and 0.15g of thixotropic agent (hydrogenated castor oil) are weighed, uniformly stirred, and made into slurry with the fineness of less than 10 mu m by a three-roll mill. The slurry is printed on a PI film substrate and is completely cured at 160 ℃/1 h.

Example 3:

synthesizing an organic silicon modified epoxy resin toughening agent: uniformly mixing 15g of amino silicone oil (the viscosity is 8000mPa & s, the amino content is 2.5%) and 100g of bisphenol A epoxy resin (the viscosity is 20000mPa & s, the epoxy value is 0.44), stirring for 3.0h, heating to 140 ℃, and reacting for 3.5h to obtain the organic silicon modified epoxy resin toughening agent R-003.

30g of spherical silver powder (particle size of 200-500 nm), 50g of flake silver powder (2.0-8.0 mu m), 9.7g of polyetherimide resin (Sabic, Seiki basic Industrial Co., Ltd.), 3.2g of naphthalene type epoxy resin (HP-4700, Dajapan ink chemical industry Co., Ltd.), 2.0g of curing agent (dicyandiamide), 0.08g of accelerator (1-cyanoethyl-2-ethyl-4-methylimidazole), 1.8g of flexibilizer (R-003), 3.0g of ethylene glycol monobutyl ether acetate, 0.05g of silane coupling agent (KBM-603), 0.05g of dispersant (Silok-7096) and 0.12g of thixotropic agent (hydrogenated castor oil) are weighed, uniformly stirred, and made into a slurry with the fineness of less than 10 mu m by a three-roll mill. The slurry is printed on a PI film substrate and is completely cured at 160 ℃/1 h.

Example 4:

synthesizing an organic silicon modified epoxy resin toughening agent: 60g of amino silicone oil (viscosity is 55000 mPas, amino content is 0.5%) and 100g of hydrogenated bisphenol F epoxy resin (viscosity is 1500 mPas, epoxy value is 0.48) are uniformly mixed, stirred for 2.5h, heated to 145 ℃ and reacted for 3.5h, thus obtaining the organic silicon modified epoxy resin toughening agent R-004.

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 (with the particle size of 2.0-10.0 μm), 10.0g of polyamide-imide resin (Vylomax, Toyobo Japan Co., Ltd.), 3.4g of naphthalene-type epoxy resin (Dainippon ink chemical industry Co., Ltd., HP-4700), 1.8g of curing agent (dicyandiamide), 0.08g of accelerator (1-cyanoethyl-2-ethyl-4-methylimidazole), 1.5g of toughener (R-004), 3.0g of ethylene glycol monobutyl ether acetate, 0.05g of silane coupling agent (KBM-603), 0.05g of dispersant (Silok-7455H) and 0.12g of thixotropic agent (organic bentonite), uniformly stirring, and preparing the slurry with the fineness of less than 10 μm by a three-roll mill. The slurry is printed on a PI film substrate and is completely cured at 160 ℃/1 h.

Example 5:

synthesizing an organic silicon modified epoxy resin toughening agent: 50g of amino silicone oil (with the viscosity of 50000 mPas and the amino content of 3.0%) and 100g of bisphenol F epoxy resin (with the viscosity of 3200 mPas and the epoxy value of 0.58) are uniformly mixed, stirred for 2.4h, heated to 130 ℃, and reacted for 4.0h to obtain the organic silicon modified epoxy resin toughening agent R-005.

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 μm), 7.0g of polyamide-imide resin (Vylomax, Toyo Boseki Kabushiki Kaisha), 2.7g of biphenyl epoxy resin, 1.3g of curing agent (dicyandiamide), 0.08g of accelerator (1-cyanoethyl-2-ethyl-4-methylimidazole), 1.2g of flexibilizer (R-005), 2.5g of ethylene glycol ethyl ether acetate, 0.05g of silane coupling agent (KBM-603), 0.05g of dispersing agent (Silok-7423) and 0.12g of thixotropic agent (organic bentonite), uniformly stirring, and preparing the slurry with the fineness of less than 10 μm by a three-roll mill. The slurry was printed on PI substrate and cured completely at 160 deg.C/1 h.

Example 6:

synthesizing an organic silicon modified epoxy resin toughening agent: 75g of amino silicone oil (with the viscosity of 65000 mPas and the amino content of 1.5%) and 100g of hydrogenated bisphenol A epoxy resin (with the viscosity of 2300 mPas and the epoxy value of 0.59) are uniformly mixed, stirred for 3.0h, heated to 140 ℃ and reacted for 3.5h to obtain the organic silicon modified epoxy resin toughening agent R-006.

Weighing 25g of spherical silver powder (with the particle size of 200-800 nm), 55g of flake silver powder (2.0-10.0 mu m), 9.4g of polyamide-imide resin (Vylomax, Nippon Toyo chemical Co., Ltd.), 3.6g of biphenyl type epoxy resin, 2.2g of curing agent (dicyandiamide), 0.1g of accelerator (1-cyanoethyl-2-ethyl-4-methylimidazole), 1.5g of flexibilizer (R-006), 3.0g of ethylene glycol ethyl ether acetate, 0.05g of silane coupling agent (KH-570), 0.05g 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 a three-roll machine. The slurry is printed on a PI film substrate and is completely cured at 160 ℃/1 h.

Example 7:

synthesizing an organic silicon modified epoxy resin toughening agent: 70g of amino silicone oil (viscosity of 58000mPa & s, amino content of 2.5%) and 100g of cyclohexyl dimethanol diglycidyl ether (viscosity of 60mPa & s, epoxy value of 0.72) are uniformly mixed, stirred for 2.5h, heated to 148 ℃ and reacted for 3.5h to obtain the organosilicon modified epoxy resin toughening agent R-007.

30g of spherical silver powder (particle size 200 to 800 nm), 50g of plate-like silver powder (2.0 to 10.0 μm), 4.4g of polyamideimide resin (Vylomax, Toyo Boseki Kaisha, Japan), 5.0g of polyetherimide resin (Sabic, Seiki industries Co., Ltd.), 1.8g of biphenyl epoxy resin, 1.8g of naphthalene epoxy resin (Dajapan ink chemical industries, Japan), 2.2g of a curing agent (diphenylmethanediamine), 0.1g of an accelerator (2-phenyl-4-methylimidazole), 1.5g of a toughener (R-007), 2.0g of ethylene glycol ethyl ether acetate, 1.0g of diethylene glycol butyl ether acetate, 0.05g of a silane coupling agent (KH-570), 0.05g of a dispersant (BYK-370), and 0.10g of a thixotropic agent (polyethylene wax) were weighed, stirred uniformly, and made into a slurry having a fineness of less than 10 μm by a three-roll mill. The slurry is printed on a PI film substrate and is completely cured at 160 ℃/1 h.

Example 8:

synthesizing an organic silicon modified epoxy resin toughening agent: 50g of amino silicone oil (viscosity is 48000mPa & s, amino content is 2.0%) and 100g of bisphenol F epoxy resin (viscosity is 3000mPa & s, epoxy value is 0.50) are uniformly mixed, stirred for 2.5h, heated to 145 ℃ and reacted for 4.0h, and the organic silicon modified epoxy resin toughening agent R-008 is obtained.

Weighing 35g of spherical silver powder (particle size 200-800 nm), 40g of flake silver powder (2.0-9.0 μm), 8.0g of polyetherimide resin (Sabic ), 4.0g of polyamideimide resin (Vylomax, Toyo Boseki Co., Ltd., Japan), 2.5g of naphthalene-type epoxy resin (Dajapan ink chemical industry Co., Ltd., HP-4700), 2.0g of polyimide modified epoxy resin, 2.0g of curing agent (diphenylmethanediamine), 0.1g of accelerator (2-phenyl-4-methylimidazole), 1.0g of flexibilizer (R-008), 0.5g of core-shell rubber particles (japanese bell jar chemical MX 153), 3.0g of diethylene glycol butyl ether acetate, 1.6g of ethylene glycol butyl ether acetate, 0.05g of silane coupling agent (KBM-603), 0.10g of dispersant (DARNC-N), 0.15g of thixotropic agent (polyethylene wax), stirring uniformly, making into slurry with fineness less than 10 μm by three-roller machine. The slurry is printed on a PI film substrate and is completely cured at 160 ℃/1 h.

Comparative example 1:

weighing 70g of flake silver powder (2.0-10.0 mu m), 16g of polyetherimide resin (SABIC), 4.8g of amino tetra-functional epoxy resin (Saudi Seisakusho materials science and technology Co., Ltd., Hunan, JD-919), 2.7g of curing agent (4, 4-diaminodiphenyl sulfone), 0.1g of accelerator (2-ethyl-4-methylimidazole), 4.0g of diethylene glycol monobutyl ether acetate, 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. The slurry is printed on a PI film substrate and is completely cured at 160 ℃/1 h.

Comparative example 2:

weighing 70g of flake silver powder (2.0-10.0 mu m), 16g of polyetherimide resin (SABIC), 4.8g of amino tetra-functional epoxy resin (SABIC, Inc., Jiannan Gshengde materials science and technology Co., Ltd.), 2.7g of curing agent (4, 4-diaminodiphenyl sulfone), 0.1g of accelerator (2-ethyl-4-methylimidazole), 2.0g of flexibilizer (polyether modified epoxy resin, Japan ADEKA, EP-1307), 4.0g of diethylene glycol monobutyl ether acetate, 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. The slurry is printed on a PI film substrate and is completely cured at 160 ℃/1 h.

Test example:

the following conductive paste performance tests were performed:

(1) testing the viscosity and the printing performance of the conductive paste;

(2) testing the resistivity of the conductive paste cured film;

(3) testing the heat resistance of the electroconductive paste cured film: testing of glass transition temperature (T) of cured films of electroconductive pastes by dynamic thermomechanical analyzer (DMA)_gTan δ peak temperature), the heat resistance of the electroconductive paste resin system was evaluated as the glass transition temperature;

(4) testing the peel strength (180 DEG peel) of the conductive paste cured film on the PI film;

(5) testing the flexibility of the cured film of the conductive paste: and (3) completely curing the conductive paste printed on the PI film, bending for 200 times, and testing the resistivity of the cured film after bending and the peel strength on the substrate.

The experimental results of the above tests are shown in table 1. The conductive paste has the advantages of good printability, good conductivity, strong bonding force, excellent heat resistance (the glass transition temperature is more than 160 ℃), excellent flexibility, suitability for PEEK, PI and other flexible base materials, and applicability to fields with high heat resistance requirements, such as automobiles, high-speed rails, aerospace, military industry and the like.

TABLE 1