Silver-plated microsphere / light-cured waterborne polyurethane flexible conductive material and preparation method thereof

Abstract

The invention discloses a preparation method of silver-plated microsphere / light-cured waterborne polyurethane acrylate. Diamine ester diol is added during synthesis of waterborne polyurethane, the content of urethane bonds on macromolecular chains is increased while the use amount of diisocyanate monomers is not changed, then the density of hydrogen bonds among polyurethane macromolecules is increased, meanwhile, hydroxyl acrylate monomers are used for blocking to form end-group carbon-carbon double bonds, and waterborne polyurethane acrylate is prepared. And mixing waterborne polyurethane, a reactive diluent, a photoinitiator and the silver-plated microspheres to prepare the silver-plated microsphere / light-cured waterborne polyurethane conductive material. The silver consumption of the silver-plated microspheres is low, and the surface silver plating amount can reach 58-75%. The preparation cost is greatly reduced, and the conductivity meets the application requirement.

Description

Technical Field

[0001] The invention belongs to the field of conductive materials, and specifically provides a silver-plated microsphere / light-cured waterborne polyurethane flexible conductive material and a preparation method thereof. Background Art

[0002] With the rapid development of flexible electronic products, the research on flexible polyurethane conductive materials has received more and more attention. The flexibility of polyurethane materials is related to the content of urethane bonds. The urethane bonds in traditional polyurethane materials are generated by the reaction of diisocyanate and the terminal hydroxyl groups of diols. The large-scale use of diisocyanates is extremely harmful to the human body and the environment. Therefore, the addition of diol monomers containing urethane bonds can increase the content of urethane bonds on the main chain of polyurethane without changing the amount of diisocyanate, thereby increasing the hydrogen bond density of polyurethane, which is of great significance for improving the performance of flexible polyurethane. In addition, the preparation of traditional polyurethane conductive materials is to mix polyurethane with silver micron conductive fillers. The diameter of micron silver conductive fillers is 0.08-0.1um, which consumes a lot of silver and is expensive. However, silver plating on the surface of glass microspheres consumes less silver, and the required amount of silver is only 0.0635-0.254 / g, and the surface silver plating amount can reach 58-75%. Compared with the same mass of micron silver conductive fillers, silver-plated microspheres consume less silver, have lower cost, and the conductivity meets the application requirements.

[0003] Therefore, this paper designs a method for preparing a silver-plated microsphere / light-cured waterborne polyurethane flexible conductive material, which is characterized in that diurethane diol increases the urethane bond on the polyurethane macromolecular chain, and at the same time, the silver-plated microsphere consumes less silver, has lower cost, and has good conductivity.

[0004] The innovation of the present invention is

[0005] Adding diaminodiol to the synthesis of waterborne polyurethane acrylate increases the content of urethane bonds on the macromolecular chain without changing the amount of diisocyanate monomer, thereby increasing the density of intermolecular hydrogen bonds. Compared with the same mass of micron silver conductive filler, the amount of silver required for silver-plated microspheres is only 0.0635-0.254 / g, and the surface silver coating can reach 58-75%. The preparation cost is greatly reduced and the conductivity meets the application requirements. Summary of the invention

[0006] The invention provides a method for preparing a silver-plated microsphere / light-cured waterborne polyurethane acrylate flexible conductive material. The diamino ester diol in the flexible conductive material increases the content of urethane bonds in the polyurethane molecular chain, and compared with the same mass of micron silver filler, the silver-plated microspheres require less silver content, lower cost and good conductivity.

[0007] In order to achieve the above technical objectives, the technical method adopted by the present invention is:

[0008] A method for preparing a silver-plated microsphere / light-cured waterborne polyurethane acrylate conductive material, the preparation steps and characteristics of which include the following:

[0009] (1) Polyether or polyester diol, diamino ester diol and diisocyanate monomer are uniformly mixed, and an organic tin catalyst is added. The reaction temperature range is 65-85°C and the reaction is carried out for 2-3 hours to obtain a waterborne polyurethane prepolymer. A carboxyl-containing hydrophilic chain extender is added and the reaction is carried out for 1-2 hours. A hydroxy acrylate monomer is added to cap the reaction and the reaction is carried out in the dark for 1.5-2.5 hours. The temperature is adjusted to 20-35°C, and triethylamine is added to react for 20-30 minutes. Deionized water is added and the mixture is emulsified at high speed and stirred in the dark for 0.5-1 hour to obtain a waterborne polyurethane acrylate (WPUA). The molar ratio of polyether or polyester diol, diamino ester diol and diisocyanate in the waterborne polyurethane prepolymer is 1:(1-7):(4-13). The molar ratio of the carboxyl-containing hydrophilic chain extender and triethylamine in the waterborne polyurethane is 1:1. The hydroxy acrylate monomer content is the residual isocyanate content in the waterborne polyurethane.

[0010] (2) Stir waterborne polyurethane acrylate (WPUA), reactive diluent and photoinitiator at 25-40°C for 0.5-1h under nitrogen to obtain mixed solution A photocurable waterborne polyurethane acrylate (PUA). Add silver-plated microspheres (Ag@HGMs) and stir at 25-40°C for 0.5-1h under nitrogen to obtain mixed solution B silver-plated microspheres / photocurable waterborne polyurethane acrylate (Ag@HGMs / PUA). The mass fractions of waterborne polyurethane acrylate, reactive diluent and photoinitiator in mixed solution A are (70-93%): (5-25%): (2-5%). The mass fractions of silver-plated microspheres and photocurable waterborne polyurethane acrylate in mixed solution B are (20-50%): (50-80%).

[0011] Furthermore, the polyether or polyester diol in step (1) is a mixture of any one or more of polycaprolactone diol (PCL), polyethylene glycol (PET), polypropylene glycol (PPG), polycarbonate diol (PCDL), and polytetramethylene glycol (PTMEG), and has a molecular weight between 500 and 2000.

[0012] Further, the general structural formula of the diamino ester diol (PCU) in step (1) is:

[0013]

[0014] Where R1 is an aliphatic alkylene group, (CH2) m , m = 2 to 6; R2 is an alkylene group, (CH2) n, n=2 to 12. The diamino ester diol is one or more of C,C-bis(2-hydroxy-1-methylethyl)N,N-(1,6-hexanediyl)bis[carbamate], C,C-bis(2-hydroxyethyl)N,N-1,6-hexanediylbis[carbamate], C,C-bis(2-hydroxyethyl)N,N-1,5-pentanediylbis[carbamate], C,C-bis(2-hydroxyethyl)N,N-1,4-butanediylbis[carbamate], C,C-bis(2-hydroxyethyl)N,N-1,3-propylenediylbis[carbamate], and C,C-bis(2-hydroxyethyl)N,N-1,2-ethanediylbis[carbamate].

[0015] Further, the diisocyanate monomer in step (1) is one or more of isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HDI), diphenylmethane diisocyanate (MDI), toluene diisocyanate (TDI), and dicyclohexylmethane diisocyanate (HMDI). The organotin catalyst is one or more of dibutyltin dilaurate, stannous octoate, dibutyltin oxide, and dibutyltin diacetate. The carboxyl-containing hydrophilic chain extender is one of dihydroxymethylbutyric acid or dihydroxymethylbutyric acid propionic acid. The hydroxyacrylate monomer is one or more of 2-hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, hydroxybutyl acrylate, hydroxybutyl methacrylate, 2-(hydroxymethyl)methyl acrylate, and 2-4-hydroxypropyl acrylate.

[0016] Furthermore, the active diluent in step (2) is one or more of isobornyl acrylate, 2-phenoxyethyl acrylate, 1,7,7-trimethylbicyclo[2,2,1]heptane-2-methylacrylate, 1,6-hexanediol diacrylate, tetrapropylene glycol diacrylate, and trimethylolpropane triacrylate; the photoinitiator is one or more of hydroxycyclohexylpropiophenone, 2-hydroxymethylphenylpropane-1-one, 2-methyl-1-(4-methylthiophenyl)-2-morpholine-1-propanone, benzophenone, 2-phenyl-2,2-dimethylamino-1-(4-morpholinephenyl)-1-butanone, and 2,4,6-trimethylbenzoyl-diphenylphosphine oxide. The silver-plated microspheres (Ag@HGMs) can refer to existing preparation technology or commercially available products. The diameter of the silver-plated microspheres is 45-75um, and the silver content on the surface of the microspheres measured by EDS spectrum is 58-75%. Beneficial Effects

[0017] The photocurable waterborne polyurethane acrylate prepared in this paper increases the content of urethane bonds on the main chain of the macromolecule by adding diamino ester diol, thereby increasing the density of intermolecular hydrogen bonds. After ultraviolet light irradiation, the photocurable waterborne polyurethane acrylate (PUA) can be cured within 15-20 seconds. After adding silver-plated microspheres, the conductivity of silver-plated microspheres / photocurable waterborne polyurethane acrylate (Ag@HGMs / PUA) was measured to be (0.85-1.37×10 -3 ). Compared with the same mass of micron silver conductive filler, the amount of silver required for silver-plated microspheres is only 0.0635-0.254 / g, and the surface silver coating can reach 58-75%, which greatly reduces the preparation cost and the conductivity meets the application requirements. Specific implementation methods

[0019] The technical solution of the present invention is further described below in conjunction with specific embodiments.

[0020] Example 1

[0021] A method for preparing a silver-plated microsphere / light-cured waterborne polyurethane acrylate conductive material, comprising the following preparation steps:

[0022] (1) 20 g of polyethylene glycol (PEG, Mn = 2000), 3.2 g of C, C-bis (2-hydroxy-1-methylethyl) N, N- (1.6-hexanediyl) bis [carbamate] (PCU) and 8.92 g of isophorone diisocyanate (IPDI) were uniformly mixed and 30 g of ethyl acetate (EAC) was added, and 0.01 g of catalyst dibutyltin dilaurate (DBTDL) was added, and the mixture was reacted at 70 ° C for 3 h. 1.8 g of dihydroxymethyl propionic acid (DMPA) and 4 g of solvent N-methylpyrrolidone (NMP) were added to react for 2 h. 0.87 g of hydroxyethyl methacrylate (HEMA) was added to react in the dark for 1 h. The mixture was cooled to 35 ° C, 1.4 g of triethylamine was added, and the mixture was stirred in the dark for 30 min. 54 g of deionized water was added for emulsification. The product obtained was waterborne polyurethane acrylate.

[0023] (2) Add 10 g of waterborne polyurethane acrylate, 4.28 g of active diluent trimethylolpropane trimethacrylate, and 0.71 g of photoinitiator 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (TPO), mix, and stir for 1 hour in the dark to obtain the product photocurable waterborne polyurethane acrylate (PUA).

[0024] (3) The silver-plated microspheres and the photocurable waterborne polyurethane acrylate were fully mixed in a ratio of 2:8 and stirred at 25-35°C for 30 minutes to obtain the silver-plated microsphere / photocurable waterborne polyurethane acrylate conductive material (Ag@HGMs / PUA).

[0025] Embodiment 1 performance test:

[0026] Curing time test: Using a rotational rheometer, set the torque to 0.01Nm, the temperature to 20°C, and the speed to 0.1rpm / min. Under the UV curing light with a wavelength of 365nm and a power of 3w, the storage modulus ΔG' before curing was 2.92kPa, the loss modulus ΔG" before curing was 2.88kPa, the storage modulus ΔG' after curing was 150.71kPa, the loss modulus ΔG" after curing was 163.57kPa, and the complete curing time was 15s.

[0027] Electrode preparation: Pour the silver-coated microsphere / light-cured waterborne polyurethane acrylate conductive material into a 3 ml threaded syringe and print a 1 cm × 2 cm electrode on a biaxially stretched film at a speed of 8 mm / min using a flexible electronic device printer.

[0028] Conductivity test: The resistance of the electrode was measured using a digital multimeter, and the conductivity of the electrode was calculated to be 1.37×10 -3 Ω / cm, the resistance under 10N pressure is 90Ω, and the current change rate under 10N pressure is 1.61%.

[0029] Example 2

[0030] A method for preparing a silver-plated microsphere / light-cured waterborne polyurethane acrylate conductive material, comprising the following preparation steps:

[0031] (1) 20 g of polyethylene glycol (PEG, Mn = 2000), 9.6 g of C, C-bis (2-hydroxy-1-methylethyl) N, N- (1.6-hexanediyl) bis [carbamate] (PCU) and 15.8 g of isophorone diisocyanate (IPDI) were uniformly mixed and 35 g of ethyl acetate (EAC) was added, and 0.01 g of catalyst dibutyltin dilaurate (DBTDL) was added, and the mixture was reacted at 70 ° C for 3 h. 2.6 g of dihydroxymethyl propionic acid (DMPA) and 6 g of solvent N-methylpyrrolidone (NMP) were added to react for 2 h. 1.6 hydroxyethyl methacrylate (HEMA) was added to react for 1 h in the dark. The mixture was cooled to 35 ° C, 1.9 g of triethylamine was added, and the mixture was stirred in the dark for 30 min. 77 g of deionized water was added for emulsification. The product obtained was waterborne polyurethane acrylate.

[0032] (2) Add 10 g of waterborne polyurethane acrylate, 4.28 g of active diluent trimethylolpropane trimethacrylate, and 0.71 g of photoinitiator 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (TPO), mix, and stir for 1 hour in the dark to obtain the product photocurable waterborne polyurethane acrylate (PUA).

[0033] (3) The silver-plated microspheres and the photocurable waterborne polyurethane acrylate were fully mixed in a ratio of 3:7 and stirred at 25-35°C for 30 minutes to obtain the silver-plated microsphere / photocurable waterborne polyurethane acrylate conductive material (Ag@HGMs / PUA).

[0034] Embodiment 2 performance test:

[0035] Curing time test: Using a rotational rheometer, set the torque to 0.01Nm, the temperature to 20°C, and the speed to 0.1rpm / min. Under the UV curing light with a wavelength of 365nm and a power of 3w, the storage modulus ΔG' before curing was 2.43kPa, the loss modulus ΔG" before curing was 2.28kPa, the storage modulus ΔG' after curing was 147.32kPa, the loss modulus ΔG" after curing was 167.29kPa, and the complete curing time was 16s.

[0036] Electrode preparation: Pour the silver-coated microsphere / light-cured waterborne polyurethane acrylate conductive material into a 3 ml threaded syringe and print a 1 cm × 2 cm electrode on a biaxially stretched film at a speed of 8 mm / min using a flexible electronic device printer.

[0037] Conductivity test: The resistance of the electrode was measured using a digital multimeter, and the conductivity of the electrode was calculated to be 1.23×10 -3 Ω / cm, the resistance under 10N pressure is 64Ω, and the current change rate under 10N pressure is 1.64%.

[0038] Example 3

[0039] A method for preparing a silver-plated microsphere / light-cured waterborne polyurethane acrylate conductive material, comprising the following preparation steps:

[0040] (1) 20 g of polyethylene glycol (PEG, Mn = 2000), 16 g of C, C-bis (2-hydroxy-1-methylethyl) N, N- (1.6-hexanediyl) bis [carbamate] (PCU) and 22.2 g of isophorone diisocyanate (IPDI) were uniformly mixed and 42 g of ethyl acetate (EAC) was added, and 0.01 g of catalyst dibutyltin dilaurate (DBTDL) was added, and the mixture was reacted at 70 ° C for 3 h. 3.3 g of dihydroxymethyl propionic acid (DMPA) and 6 g of solvent N-methylpyrrolidone (NMP) were added to react for 2 h. 1.95 g of hydroxyethyl methacrylate (HEMA) was added to react in the dark for 1 h. The mixture was cooled to 35 ° C, 2.5 g of triethylamine was added, and the mixture was stirred in the dark for 30 min. 99 g of deionized water was added for emulsification. The product obtained was waterborne polyurethane acrylate.

[0041] (2) Add 10 g of waterborne polyurethane acrylate, 4.28 g of active diluent trimethylolpropane trimethacrylate, and 0.71 g of photoinitiator 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (TPO), mix, and stir for 1 hour in the dark to obtain the product photocurable waterborne polyurethane acrylate (PUA).

[0042] (3) The silver-plated microspheres and the photocurable waterborne polyurethane acrylate were fully mixed in a ratio of 4:6 and stirred at 25-35°C for 30 minutes to obtain the silver-plated microsphere / photocurable waterborne polyurethane acrylate conductive material (Ag@HGMs / PUA).

[0043] Embodiment 3 performance test:

[0044] Curing time test: Using a rotational rheometer, set the torque to 0.01Nm, the temperature to 20°C, and the speed to 0.1rpm / min. Under the irradiation of UV curing light with a wavelength of 365nm and a power of 3w, the storage modulus ΔG' before curing was 2.54kPa, the loss modulus ΔG" before curing was 2.47kPa, the storage modulus ΔG' after curing was 152.37kPa, the loss modulus ΔG" after curing was 172.36kPa, and the complete curing time was 17s.

[0045] Electrode preparation: Pour the silver-coated microsphere / light-cured waterborne polyurethane acrylate conductive material into a 3 ml threaded syringe and print a 1 cm × 2 cm electrode on a biaxially stretched film at a speed of 8 mm / min using a flexible electronic device printer.

[0046] Conductivity test: The resistance of the electrode was measured using a digital multimeter, and the conductivity of the electrode was calculated to be 0.85×10 -3 Ω / cm, the resistance under 10N pressure is 27Ω, and the current change rate under 10N pressure is 1.63%.

[0047] Performance results test

[0048] Table 1 Performance test of light-cured waterborne polyurethane acrylate

[0049]

[0050] Table 2 Conductive performance test of silver-plated microspheres / light-cured waterborne polyurethane acrylate

[0051]

[0052]

[0053] It should be noted that the above embodiments are only partial embodiments of the preferred methods for implementing the present invention, rather than all embodiments. Obviously, based on the above embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

Claims

1. A method for preparing a silver-plated microsphere / light-cured waterborne polyurethane acrylate flexible conductive material, the preparation method comprising the following steps: (1) Polyether or polyester diol, diamino ester diol and diisocyanate monomer are uniformly mixed, an organic tin catalyst is added, the reaction temperature range is 65-85°C, the reaction is carried out for 2-3 hours, and a carboxyl-containing hydrophilic chain extender is added for 1-2 hours to obtain a waterborne polyurethane prepolymer; a hydroxyl acrylate monomer is added for end-capping and the reaction is carried out in the dark for 1.5-2.5 hours; the temperature is adjusted to 20-35°C, and triethylamine is added for reaction for 20-30 minutes; deionized water is added for high-speed emulsification and stirring in the dark for 0.5-1 hour to obtain a waterborne polyurethane acrylate WPUA; the molar ratio of polyether or polyester diol, diamino ester diol and diisocyanate in the waterborne polyurethane prepolymer is 1:(1-7):(4-13); the molar ratio of the carboxyl-containing hydrophilic chain extender and triethylamine in the waterborne polyurethane is 1:1; and the molar ratio of the hydroxyl acrylate monomer and the remaining isocyanate in the reaction system is 1:

1. (2) Add waterborne polyurethane acrylate WPUA, active diluent and photoinitiator and stir at 25-40°C for 0.5-1h under nitrogen to obtain mixed solution A (light-cured waterborne polyurethane acrylate PUA); add silver-plated microspheres Ag@HGMs and stir at 25-40°C for 0.5-1h under nitrogen to obtain mixed solution B (light-cured waterborne polyurethane acrylate Ag@HGMs / PUA); the mass fractions of waterborne polyurethane acrylate, active diluent and photoinitiator in mixed solution A are (70-93%):(5-25%):(2-5%); the mass fractions of silver-plated microspheres and light-cured waterborne polyurethane acrylate in mixed solution B are (20-50%):(50-80%).

2. The method for preparing the silver-plated microsphere / light-cured waterborne polyurethane acrylate flexible conductive material according to claim 1, characterized in that: The polyether or polyester diol in step (1) is a mixture of any one or more of polycaprolactone diol PCL, polyethylene glycol PET, polypropylene glycol PPG, polycarbonate diol PCDL, and polytetramethylene glycol PTMEG, and the molecular weight is between 500-2000.

3. The method for preparing the silver-plated microsphere / light-cured waterborne polyurethane acrylate flexible conductive material according to claim 1, characterized in that: The general structural formula of the diamino ester diol PCU in step (1) is: Where R1 is an aliphatic alkylene group, (CH2) m , m = 2 to 6; R2 is an alkylene group, (CH2) n , n=2 to 12. The diamino ester diol is one or more of C,C-bis(2-hydroxy-1-methylethyl)N,N-(1,6-hexanediyl)bis[carbamate], C,C-bis(2-hydroxyethyl)N,N-1,6-hexanediylbis[carbamate], C,C-bis(2-hydroxyethyl)N,N-1,5-pentanediylbis[carbamate], C,C-bis(2-hydroxyethyl)N,N-1,4-butanediylbis[carbamate], C,C-bis(2-hydroxyethyl)N,N-1,3-propylenediylbis[carbamate], and C,C-bis(2-hydroxyethyl)N,N-1,2-ethanediylbis[carbamate].

4. The method for preparing the silver-plated microsphere / light-cured waterborne polyurethane acrylate flexible conductive material according to claim 1, characterized in that: The diisocyanate monomer in step (1) is one or more of isophorone diisocyanate IPDI, hexamethylene diisocyanate HDI, diphenylmethane diisocyanate MDI, toluene diisocyanate TDI, and dicyclohexylmethane diisocyanate HMDI; the organotin catalyst is one or more of dibutyltin dilaurate, stannous octoate, dibutyltin oxide, and dibutyltin diacetate; the carboxyl-containing hydrophilic chain extender is one of dihydroxymethylbutyric acid or dihydroxymethylbutyric acid propionic acid; the hydroxyacrylate monomer is one or more of 2-hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, hydroxybutyl acrylate, hydroxybutyl methacrylate, 2-(hydroxymethyl)methyl acrylate, and 2-4-hydroxypropyl acrylate.

5. The method for preparing the silver-plated microsphere / light-cured waterborne polyurethane acrylate flexible conductive material according to claim 1, characterized in that: The active diluent in step (2) is one or more of isobornyl acrylate, 2-phenoxyethyl acrylate, 1,7,7-trimethylbicyclo[2,2,1]heptane-2-methylacrylate, 1,6-hexanediol diacrylate, tetrapropylene glycol diacrylate, and trimethylolpropane triacrylate; the photoinitiator is one or more of hydroxycyclohexylpropiophenone, 2-hydroxymethylphenylpropane-1-one, 2-methyl-1-(4-methylthiophenyl)-2-morpholine-1-propanone, dibenzophenone, 2-phenyl-2,2-dimethylamino-1-(4-morpholinephenyl)-1-butanone, and 2,4,6-trimethylbenzoyl-diphenylphosphine oxide; the silver-plated microspheres (Ag@HGMs) can refer to existing preparation technology or can use commercially available products, the diameter of the silver-plated microspheres is 45-75um, and the silver content on the surface of the microspheres measured by EDS energy spectrum is 58-75%.

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