Nanosilver coating for low-temperature high-humidity thawing equipment and preparation method thereof

Abstract

The application relates to the technical field of paint, and particularly discloses a kind of nano-silver paint for low-temperature high-humidity thawing equipment and a preparation method thereof;Including the following steps: S1: with sodium oleate modified graphite loaded nano-silver wire, sodium oleate modified filler is obtained;S2: take acrylic acid, methyl methacrylate, methyl acrylate, allyl trimethyl ammonium chloride, hydroxyethyl methacrylate, styrene, butyl acrylate, di-tert-pentyl peroxide, vinyl silicone oil, sodium oleate modified filler, ethanedithiol, azobis isobutyronitrile, prepare nano-silver A;S3: take isocyanate group terminated polyurethane prepolymer as a template agent, prepare nano-silver B;S4: take polyurethane acrylate, polyacrylate, acetone, photoinitiator, nano-silver A, nano-silver B, mix evenly, get nano-silver paint.

Description

Technical Field

[0001] The invention relates to the technical field of coatings, and particularly discloses a nano silver coating for low-temperature and high-humidity thawing equipment and a preparation method thereof. Background Art

[0002] When nanosilver coating is used in low-temperature and high-humidity thawing equipment, it has the following advantages: Nanosilver has broad-spectrum antibacterial properties, and inhibits the growth of various bacteria such as Gram-negative bacteria and Gram-positive bacteria by releasing silver ions. It can effectively prevent microbial contamination and maintain the freshness and nutritional content of meat; and the synthesis method of nanosilver is green and environmentally friendly, which can reduce the impact on the environment.

[0003] In addition to excellent antibacterial properties, nanosilver coatings for low-temperature and high-humidity thawing equipment also require good scratch resistance and good low-temperature environment stability to extend the service life of the equipment. Therefore, in the existing technology, functional additives are often added to nanosilver coatings, or nanosilver, coating matrix, etc. are modified. However, problems such as the dispersion and compatibility of functional additives and nanosilver in the coating matrix often lead to a decline in coating quality. In summary, it is of great significance to study a nanosilver coating for low-temperature and high-humidity thawing equipment with good antibacterial properties, scratch resistance, and low-temperature resistance, and a preparation method thereof, in order to obtain a coating with stable quality. Summary of the Invention

[0004] The object of the present invention is to provide a nano silver coating for low-temperature and high-humidity thawing equipment and a preparation method thereof, so as to solve the problems raised in the prior art.

[0005] To achieve the above object, the present invention provides the following technical solution: A method for preparing a nano-silver coating for low-temperature and high-humidity thawing equipment, comprising the following steps: S1: dissolving sodium oleate in water, introducing ammonia gas, heating the oil bath to 45-55°C, adding graphite-loaded nano-silver wires, maintaining the temperature and stirring, filtering, washing, and drying to obtain a sodium oleate-modified filler;

[0006] S2: Take acrylic acid, methyl methacrylate, methyl acrylate, allyltrimethylammonium chloride, hydroxyethyl methacrylate, styrene, butyl acrylate, and di-tert-amyl peroxide, and disperse them evenly to obtain a mixed monomer;

[0007] Take di-tert-amyl peroxide, vinyl silicone oil, and sodium oleate modified filler, add a mixed solvent and stir evenly, heat to 140-145°C and keep warm for 20-30 minutes, add the mixed monomer dropwise, cool to 80-85°C, add ethanedithiol and azobisisobutyronitrile, keep warm for 2-3 hours, and remove the solvent to obtain nanosilver A;

[0008] S3: Take isocyanate-terminated polyurethane prepolymer as a template, adjust the pH to 4-6, add AgNO3 aqueous solution, stir evenly, and then add ascorbic acid dropwise under inert gas protection to obtain nanosilver B;

[0009] S4: Take polyurethane acrylate, polyacrylate, acetone, photoinitiator, nanosilver A, and nanosilver B, mix them evenly, and obtain nanosilver coating.

[0010] More optimally, the nanosilver coating comprises the following raw materials, calculated by mass: 20-25 parts of polyurethane acrylate, 15-20 parts of polyacrylate, 30-40 parts of acetone, 0.1-0.2 parts of photoinitiator, 1-2 parts of nanosilver A, and 1-2 parts of nanosilver B.

[0011] More optimally, the sodium oleate modified filler comprises the following raw materials, calculated by weight: 0.4-0.6 parts of sodium oleate, 200-400 parts of water, and 4-6 parts of graphite-supported nanosilver wires;

[0012] More optimally, the mixed monomer comprises the following raw materials, calculated by mass: 6-8 parts of acrylic acid, 2-3 parts of methyl methacrylate, 2-3 parts of methyl acrylate, 4-5 parts of allyltrimethylammonium chloride, 8-10 parts of hydroxyethyl methacrylate, 3-4 parts of styrene, 10-12 parts of butyl acrylate, and 1-3 parts of di-tert-amyl peroxide;

[0013] The vinyl silicone oil has a molecular weight of 500 and a vinyl content of 8%;

[0014] The nanosilver A comprises the following raw materials, calculated by mass: 6-8 parts of acrylic acid, 2-3 parts of methyl methacrylate, 2-3 parts of methyl acrylate, 4-5 parts of allyltrimethylammonium chloride, 8-10 parts of hydroxyethyl methacrylate, 3-4 parts of styrene, 10-12 parts of butyl acrylate, 80-100 parts of a mixed solvent, 8-12 parts of vinyl silicone oil, 80-100 parts of sodium oleate modified filler, 0.5-0.8 parts of ethanedithiol, and 0.2-0.3 parts of azobisisobutyronitrile;

[0015] The mixed solvent is diethylene glycol butyl ether and dipropylene glycol butyl ether in a mass ratio of 1:1.

[0016] More optimally, in the nanosilver B, the mass ratio of the template, ascorbic acid and silver nitrate is (20-30): (8-10): (1-2).

[0017] More optimally, the preparation of the isocyanate-terminated polyurethane prepolymer includes the following steps: taking polyethylene glycol, castor oil, dihydroxybenzoic acid, trimethylolpropane, and acetone, stirring evenly, adding isophorone diisocyanate and triphenylmethane triisocyanate after the temperature reaches 68~70°C, adding a tin catalyst dropwise, and stirring for 3~4 hours to obtain the isocyanate-terminated polyurethane prepolymer.

[0018] More optimally, the isocyanate-terminated polyurethane prepolymer includes the following raw materials, calculated by mass: 13-15 parts of polyethylene glycol, 3-4 parts of castor oil, 2-3 parts of dihydroxybenzoic acid, 2-3 parts of trimethylolpropane, 25-30 parts of acetone, 10-12 parts of isophorone diisocyanate, 4-6 parts of triphenylmethane triisocyanate (4,4ˊ,4〞-triphenylmethane triisocyanate), and 0.2-0.4 parts of tin catalyst (dibutyltin dilaurate).

[0019] More optimally, the preparation of the polyurethane acrylate includes the following steps: taking an isocyanate-terminated polyurethane prepolymer, heating it to 60-70°C, adding hydroxyethyl methacrylate, stirring the reaction until the -NCO content reaches the theoretical end point, stopping the reaction, and removing the solvent by rotary evaporation to obtain polyurethane acrylate.

[0020] More optimally, the polyurethane acrylate comprises the following raw materials, calculated by weight: 10 to 15 parts of isocyanate-terminated polyurethane prepolymer and 2 to 3 parts of hydroxyethyl methacrylate.

[0021] More optimally, the preparation of the graphite-loaded silver nanowires includes the following steps: adding graphite to ethanol and uniformly dispersing it by ultrasonication to obtain a graphite dispersion; heating the graphite dispersion to 150-160° C. and keeping it warm for 10-15 minutes, adding polyvinyl pyrrolidone and heating it for 20-30 minutes, adding a 0.2 mmol / L CuCl2 aqueous solution and a 0.2 mmol / L AgNO3 aqueous solution, stirring for 5-8 minutes, adding a 3 mmol / L AgNO3 aqueous solution, stirring for 20-30 minutes, filtering, washing, and drying to obtain graphite-loaded silver nanowires;

[0022] The graphite dispersion includes the following raw materials, calculated by mass: 2 to 3 parts of graphite and 150 to 200 parts of ethanol; the graphite-loaded nanosilver wires include the following raw materials, calculated by mass: 100 parts of graphite dispersion, 2 to 3 parts of polyvinyl pyrrolidone, 10 to 12 parts of a 0.2 mmol / L CuCl2 aqueous solution, 20 to 25 parts of a 0.2 mmol / L AgNO3 aqueous solution, and 10 to 15 parts of a 3 mmol / L AgNO3 aqueous solution.

[0023] More optimally, the curing conditions of the nano silver coating are: temperature 45-55°C, 800-1000 mj / cm2 Expose to ultraviolet light until film is formed.

[0024] Compared with the prior art, the present invention has the following beneficial effects: preparing a nanosilver coating, comprising polyurethane acrylate, polyacrylate, a photoinitiator, nanosilver A, and nanosilver B; wherein the nanosilver A is modified graphite-supported nanosilver wires, the nanosilver wires grown with graphite as a base point have more excellent dispersion stability, and the graphite can improve the mechanical properties of the coating; treating the graphite-supported nanosilver wires with sodium oleate to improve dispersibility and introduce double bonds that can participate in the next reaction, and then modifying them with an acrylic mixed monomer and vinyl silicone oil, wherein styrene improves the waterproof effect of the coating, and allyltrimethylammonium chloride and nanosilver work together to improve the antibacterial effect, the silicone oil having low surface tension and acting as a leveling agent, and having good flexibility at low temperatures, thereby improving the low-temperature stability of the coating; the nanosilver A modified by the above method has good antibacterial and low-temperature resistance, and has good compatibility with the polyurethane acrylate and polyacrylate in the coating;

[0025] Nanosilver B is a nanosilver particle prepared using an isocyanate-terminated polyurethane prepolymer as a template. Compared to nanosilver wires, nanosilver powder has better antibacterial properties. Therefore, the use of nanosilver A and nanosilver B together can simultaneously improve the mechanical and antibacterial properties of the coating. The nanosilver particles prepared using the hyperbranched template have uniform particle size and good dispersion stability. The polyurethane acrylate in the coating is also prepared using the isocyanate-terminated polyurethane prepolymer as a raw material. The two have similar structures, which improves compatibility. The polyurethane structure has good wear resistance, which is conducive to improving scratch resistance. At the same time, the presence of castor oil also improves the mechanical properties and low-temperature stability of the coating.

[0026] In summary, the nanosilver coating prepared by the present invention has excellent mechanical properties, good scratch resistance, good antibacterial properties and low-temperature stability. Since nanosilver A and nanosilver B have good compatibility with polyurethane acrylate and polyacrylate, when used in combination according to the formula of the present invention, the performance degradation caused by problems such as dispersibility is greatly reduced; after the nanosilver coating is irradiated with ultraviolet light, it is further cross-linked under the action of a photoinitiator to obtain a coating of excellent quality. DETAILED DESCRIPTION

[0027] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0028] The following parts are by mass unless otherwise specified;

[0029] Preparation method of graphite-supported silver nanowires: take 3 parts of graphite, add 180 parts of ethanol, and disperse uniformly by ultrasonication to obtain a graphite dispersion; take 100 parts of the graphite dispersion, heat to 160°C and keep warm for 15 minutes, add 3 parts of polyvinyl pyrrolidone, heat for 20 minutes, add 12 parts of 0.2 mmol / L CuCl2 aqueous solution and 25 parts of 0.2 mmol / L AgNO3 aqueous solution, stir for 5 minutes, add 15 parts of 3 mmol / L AgNO3 aqueous solution, stir for 30 minutes, filter, wash, and dry to obtain graphite-supported silver nanowires;

[0030] Example 1: S1: Dissolve 0.5 parts of sodium oleate in 300 parts of water, stir to dissolve, introduce ammonia gas, heat to 50°C in an oil bath, add 5 parts of graphite-supported nanosilver wires, keep warm and stir for 20 minutes, vacuum filter, wash, and dry to obtain a sodium oleate-modified filler;

[0031] S2: Take 8 parts of acrylic acid, 2 parts of methyl methacrylate, 2 parts of methyl acrylate, 5 parts of allyltrimethylammonium chloride, 9 parts of hydroxyethyl methacrylate, 4 parts of styrene, 10 parts of butyl acrylate, and 2 parts of di-tert-amyl peroxide, and disperse them evenly to obtain a mixed monomer;

[0032] 100 parts of a mixed solvent, 0.4 parts of di-tert-amyl peroxide, 10 parts of vinyl silicone oil, and 90 parts of a sodium oleate modified filler were added to a reaction kettle, and the temperature was raised to 145° C. and kept warm for 30 minutes. The mixed monomers were added dropwise. After the addition was complete, the reaction kettle was cooled to 80° C., 0.6 parts of ethanedithiol and 0.3 parts of azobisisobutyronitrile were added, and the temperature was kept warm for 3 hours. The solvent was removed to obtain nanosilver A.

[0033] S3: In a three-necked flask equipped with a polytetrafluoroethylene stirring rod, a condenser, and a nitrogen conduit, 13 parts of polyethylene glycol, 4 parts of castor oil, 3 parts of dihydroxybenzoic acid, 3 parts of trimethylolpropane, and 30 parts of acetone were added and stirred evenly. After the temperature reached 70°C, 11 parts of isophorone diisocyanate and 5 parts of triphenylmethane triisocyanate were added, and 0.3 parts of dibutyltin dilaurate was added dropwise. The mixture was stirred for 4 hours to obtain an isocyanate-terminated polyurethane prepolymer;

[0034] S4: Take isocyanate-terminated polyurethane prepolymer as template, adjust the pH to 5, add 0.1 mol / L AgNO3 aqueous solution, stir evenly, and then slowly add ascorbic acid dropwise under inert gas protection to obtain nanosilver B; the mass ratio of template, ascorbic acid and silver nitrate is 25:8:1;

[0035] S5: Take 12 parts of isocyanate-terminated polyurethane prepolymer, raise the temperature to 65°C, add 3 parts of hydroxyethyl methacrylate, and stir to react until the -NCO content reaches the theoretical end point, stop the reaction, and remove the solvent by rotary evaporation to obtain polyurethane acrylate;

[0036] S6: Take 22 parts of polyurethane acrylate, 18 parts of polyacrylate, 40 parts of acetone, 0.2 parts of photoinitiator, 1.5 parts of nanosilver A, and 2 parts of nanosilver B, mix them evenly, and obtain a nanosilver coating.

[0037] Example 2: S1: 0.4 parts of sodium oleate was dissolved in 300 parts of water, stirred to dissolve, ammonia gas was introduced, and an oil bath was heated to 50°C. 4 parts of graphite-supported nanosilver wires were added, and the mixture was stirred and maintained at this temperature for 20 minutes. The mixture was vacuum filtered, washed, and dried to obtain a sodium oleate-modified filler.

[0038] S2: 6 parts of acrylic acid, 3 parts of methyl methacrylate, 2 parts of methyl acrylate, 5 parts of allyltrimethylammonium chloride, 8 parts of hydroxyethyl methacrylate, 4 parts of styrene, 10 parts of butyl acrylate, and 3 parts of di-tert-amyl peroxide are uniformly dispersed to obtain a mixed monomer;

[0039] 100 parts of a mixed solvent, 0.4 parts of di-tert-amyl peroxide, 8 parts of vinyl silicone oil, and 80 parts of a sodium oleate modified filler were added to a reaction kettle, and the temperature was raised to 145° C. and kept warm for 30 minutes. The mixed monomers were added dropwise. After the addition was complete, the reaction kettle was cooled to 80° C., 0.6 parts of ethanedithiol and 0.3 parts of azobisisobutyronitrile were added, and the temperature was kept warm for 3 hours. The solvent was removed to obtain nanosilver A.

[0040] S3: In a three-necked flask equipped with a polytetrafluoroethylene stirring rod, a condenser, and a nitrogen conduit, 15 parts of polyethylene glycol, 4 parts of castor oil, 2 parts of dihydroxybenzoic acid, 2 parts of trimethylolpropane, and 30 parts of acetone were added and stirred evenly. After the temperature reached 70°C, 10 parts of isophorone diisocyanate and 6 parts of triphenylmethane triisocyanate were added, and 0.3 parts of dibutyltin dilaurate was added dropwise. The mixture was stirred for 4 hours to obtain an isocyanate-terminated polyurethane prepolymer;

[0041] S4: Take isocyanate-terminated polyurethane prepolymer as template, adjust the pH to 5, add 0.1 mol / L AgNO3 aqueous solution, stir evenly, and then slowly add ascorbic acid dropwise under inert gas protection to obtain nanosilver B; the mass ratio of template, ascorbic acid and silver nitrate is 20:8:1;

[0042] S5: Take 10 parts of isocyanate-terminated polyurethane prepolymer, raise the temperature to 65°C, add 2 parts of hydroxyethyl methacrylate, and stir to react until the -NCO content reaches the theoretical end point, stop the reaction, and remove the solvent by rotary evaporation to obtain polyurethane acrylate;

[0043] S6: Take 20 parts of polyurethane acrylate, 20 parts of polyacrylate, 40 parts of acetone, 0.2 parts of photoinitiator, 2 parts of nanosilver A, and 1 part of nanosilver B, mix them evenly to obtain a nanosilver coating.

[0044] Example 3: S1: 0.6 parts of sodium oleate was dissolved in 300 parts of water, stirred and dissolved, ammonia gas was introduced, and an oil bath was heated to 50°C. 6 parts of graphite-supported nanosilver wires were added, and the mixture was stirred and kept warm for 20 minutes. The mixture was vacuum filtered, washed, and dried to obtain a sodium oleate-modified filler.

[0045] S2: Take 8 parts of acrylic acid, 2 parts of methyl methacrylate, 3 parts of methyl acrylate, 4 parts of allyltrimethylammonium chloride, 80 parts of hydroxyethyl methacrylate, 4 parts of styrene, 10 parts of butyl acrylate, and 2 parts of di-tert-amyl peroxide, and disperse them evenly to obtain a mixed monomer;

[0046] 100 parts of a mixed solvent, 0.4 parts of di-tert-amyl peroxide, 12 parts of vinyl silicone oil, and 100 parts of a sodium oleate modified filler were added to a reaction kettle, and the temperature was raised to 145° C. and kept warm for 30 minutes. The mixed monomers were added dropwise. After the addition was complete, the reaction kettle was cooled to 80° C., 0.6 parts of ethanedithiol and 0.3 parts of azobisisobutyronitrile were added, and the temperature was kept warm for 3 hours. The solvent was removed to obtain nanosilver A.

[0047] S3: In a three-necked flask equipped with a polytetrafluoroethylene stirring rod, a condenser, and a nitrogen conduit, 13 parts of polyethylene glycol, 3 parts of castor oil, 3 parts of dihydroxybenzoic acid, 3 parts of trimethylolpropane, and 30 parts of acetone were added and stirred evenly. After the temperature reached 70°C, 12 parts of isophorone diisocyanate and 4 parts of triphenylmethane triisocyanate were added, and 0.3 parts of dibutyltin dilaurate was added dropwise. The mixture was stirred for 4 hours to obtain an isocyanate-terminated polyurethane prepolymer;

[0048] S4: Take isocyanate-terminated polyurethane prepolymer as template, adjust the pH to 5, add 0.1 mol / L AgNO3 aqueous solution, stir evenly, and then slowly add ascorbic acid dropwise under inert gas protection to obtain nanosilver B; the mass ratio of template, ascorbic acid and silver nitrate is 30:10:2;

[0049] S5: Take 15 parts of isocyanate-terminated polyurethane prepolymer, raise the temperature to 65°C, add 3 parts of hydroxyethyl methacrylate, and stir to react until the -NCO content reaches the theoretical end point, stop the reaction, and remove the solvent by rotary evaporation to obtain polyurethane acrylate;

[0050] S6: Take 25 parts of polyurethane acrylate, 15 parts of polyacrylate, 40 parts of acetone, 0.2 parts of photoinitiator, 1 part of nanosilver A, and 2 parts of nanosilver B, mix them evenly to obtain a nanosilver coating.

[0051] Comparative Example 1 (changing the addition ratio of nanosilver A and nanosilver B, and the remaining method steps are consistent with Example 1): 22 parts of polyurethane acrylate, 18 parts of polyacrylate, 40 parts of acetone, 0.2 parts of photoinitiator, 0.5 parts of nanosilver A, and 3 parts of nanosilver B were mixed uniformly to obtain a nanosilver coating.

[0052] Comparative Example 2 (changing the addition ratio of nanosilver A and nanosilver B, the remaining method steps are consistent with Example 1): 22 parts of polyurethane acrylate, 18 parts of polyacrylate, 40 parts of acetone, 0.2 parts of photoinitiator, 3 parts of nanosilver A, and 0.5 parts of nanosilver B are mixed uniformly to obtain a nanosilver coating.

[0053] Comparative Example 3 (the preparation methods of nanosilver A and nanosilver B were modified, and the remaining steps were the same as those of Example 1): S1: 0.5 parts of sodium oleate was dissolved in 300 parts of water, stirred to dissolve, ammonia gas was introduced, and the oil bath was heated to 50°C. 5 parts of graphite-supported nanosilver wires were added, and the mixture was stirred and maintained for 20 minutes. The mixture was vacuum filtered, washed, and dried to obtain sodium oleate-modified filler A.

[0054] Dissolve 0.5 parts of sodium oleate in 300 parts of water, stir to dissolve, introduce ammonia gas, heat to 50°C in an oil bath, add 5 parts of granular nanosilver, keep stirring for 20 minutes, vacuum filter, wash, and dry to obtain sodium oleate modified filler B;

[0055] S2: 8 parts of acrylic acid, 2 parts of methyl methacrylate, 2 parts of methyl acrylate, 5 parts of allyltrimethylammonium chloride, 9 parts of hydroxyethyl methacrylate, 4 parts of styrene, 10 parts of butyl acrylate, and 2 parts of di-tert-amyl peroxide were uniformly dispersed to obtain a mixed monomer; 100 parts of a mixed solvent, 0.4 parts of di-tert-amyl peroxide, 10 parts of vinyl silicone oil, and 90 parts of sodium oleate modified filler A were added to a reaction kettle, the temperature was raised to 145°C and kept warm for 30 minutes, and the mixed monomer was added dropwise. After the addition was complete, the reaction kettle was cooled to 80°C, 0.6 parts of ethanedithiol and 0.3 parts of azobisisobutyronitrile were added, the temperature was kept warm for 3 hours, and the solvent was removed to obtain intermediate A;

[0056] 8 parts of acrylic acid, 2 parts of methyl methacrylate, 2 parts of methyl acrylate, 5 parts of allyltrimethylammonium chloride, 9 parts of hydroxyethyl methacrylate, 4 parts of styrene, 10 parts of butyl acrylate, and 2 parts of di-tert-amyl peroxide were uniformly dispersed to obtain a mixed monomer; 100 parts of a mixed solvent, 0.4 parts of di-tert-amyl peroxide, 10 parts of vinyl silicone oil, and 90 parts of sodium oleate modified filler B were added to a reaction kettle, the temperature was raised to 145°C and kept warm for 30 minutes, and the mixed monomer was added dropwise. After the addition was complete, the reaction kettle was cooled to 80°C, 0.6 parts of ethanedithiol and 0.3 parts of azobisisobutyronitrile were added, the temperature was kept warm for 3 hours, and the solvent was removed to obtain intermediate B;

[0057] S3: In a three-necked flask equipped with a polytetrafluoroethylene stirring rod, a condenser, and a nitrogen conduit, 13 parts of polyethylene glycol, 4 parts of castor oil, 3 parts of dihydroxybenzoic acid, 3 parts of trimethylolpropane, and 30 parts of acetone were added and stirred evenly. After the temperature reached 70°C, 11 parts of isophorone diisocyanate and 5 parts of triphenylmethane triisocyanate were added, and 0.3 parts of dibutyltin dilaurate was added dropwise. The mixture was stirred for 4 hours to obtain an isocyanate-terminated polyurethane prepolymer;

[0058] S4: Take 3 parts of isocyanate-terminated polyurethane prepolymer, heat to 65°C, add 10 parts of intermediate A, stir and react for 4 hours, stop the reaction, and remove the solvent by rotary evaporation to obtain nanosilver A;

[0059] Take 3 parts of isocyanate-terminated polyurethane prepolymer, heat to 65°C, add 10 parts of intermediate B, stir and react for 4 hours, stop the reaction, and remove the solvent by rotary evaporation to obtain nanosilver B;

[0060] S5: Take 12 parts of isocyanate-terminated polyurethane prepolymer, raise the temperature to 65°C, add 3 parts of hydroxyethyl methacrylate, and stir to react until the -NCO content reaches the theoretical end point, stop the reaction, and remove the solvent by rotary evaporation to obtain polyurethane acrylate;

[0061] S6: Take 22 parts of polyurethane acrylate, 18 parts of polyacrylate, 40 parts of acetone, 0.2 parts of photoinitiator, 1.5 parts of nanosilver A, and 2 parts of nanosilver B, mix them evenly, and obtain a nanosilver coating.

[0062] Comparative Example 4 (changing the addition ratio of polyurethane acrylate and polyacrylate, the remaining method steps are consistent with Example 1): 12 parts of polyurethane acrylate, 28 parts of polyacrylate, 40 parts of acetone, 0.2 parts of photoinitiator, 1.5 parts of nanosilver A, and 2 parts of nanosilver B are mixed uniformly to obtain a nanosilver coating.

[0063] In the above examples, the test methods used are conventional methods unless otherwise specified; the raw materials used are commercially available unless otherwise specified, and the raw materials are as follows: graphite (expanded graphite 150 mesh, Henan Huawen Chemical Co., Ltd.); ethanol (CAS: 64-17-5); polyvinyl pyrrolidone (S30268, Shanghai Yuanye); sodium oleate (S30245, Shanghai Yuanye); acrylic acid (CAS: 79-10-7); methyl methacrylate (CAS: 80-62 -6); methyl acrylate (CAS: 96-33-3); allyltrimethylammonium chloride (S70384, Shanghai Yuanye); hydroxyethyl methacrylate (CAS: 868-77-9); styrene (CAS: 100-42-5); butyl acrylate (CAS: 141-32-2); di-tert-amyl peroxide (CAS: 10508-09-5); diethylene glycol butyl ether (CAS: 112-34-5); dipropylene glycol butyl ether (CAS: 35884-42- 5); vinyl silicone oil (molecular weight 500, vinyl content 8%, Shanghai Jiadeer Chemical Technology Co., Ltd.); ethanedithiol (CAS: 540-63-6); azobisisobutyronitrile (CAS: 78-67-1); polyethylene glycol (polyethylene glycol 1000, Shanghai Fangye Chemical Co., Ltd.); castor oil (S24344, Shanghai Yuanye); dihydroxybenzoic acid (CAS: 99-10-5); trimethylolpropane (CAS: 77-99-6); acetone (CAS: 67 -64-1); isophorone diisocyanate (CAS: 4098-71-9); 4,4ˊ,4〞-triphenylmethane triisocyanate (CAS: 2422-91-5); dibutyltin dilaurate (CAS: 77-58-7); ascorbic acid (CAS: 50-81-7); photoinitiator (photoinitiator 1173, CAS: 7473-98-5); particulate nanosilver (ABZW-12-5, Biotech); polyacrylate (TX2216, Yingxin).

[0064] Experiment: Take the nano silver coatings prepared in Examples 1 to 3 and Comparative Examples 1 to 4; (1) put them into a well-sealed container with a volume of 0.5 L, seal it and place it in an environment of -100°C to observe whether there are abnormal phenomena such as agglomeration, delamination and precipitation; (2) apply them on a standard steel plate with a thickness of 0.1 mm; at a temperature of 50°C and a 1000 mj / cm 2 The film was dried under ultraviolet light to obtain a sample; the antibacterial rate was determined according to GB21551.2-2010; (3) the scratch resistance of the sample was tested according to GB / T9279-2007 (scratch tester); the load weight was 150g; the specific data are shown in the table below;

[0065]

[0066] Conclusion: Comparative Examples 1 and 2 change the addition ratio of nanosilver A and nanosilver B, and the performance is not as good as that of the embodiment, which shows that the addition amount of the two nanosilver needs to be controlled; Comparative Example 3 changes the preparation method of nanosilver A and nanosilver B, and the performance is not as good as that of the embodiment due to problems such as grafting rate; Comparative Example 4 changes the addition ratio of polyurethane acrylate and polyacrylate, and the scratch resistance is significantly reduced, which shows the importance of their addition amount; In summary, the nanosilver coating prepared by the present invention has excellent antibacterial properties, low temperature resistance, and scratch resistance.

[0067] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations that come within the meaning and range of equivalents of the claims be embraced therein.

Claims

1. A method for preparing a nano silver coating for low-temperature and high-humidity thawing equipment, characterized in that: The following steps are involved: S1: Sodium oleate is dissolved in water, ammonia is introduced, and an oil bath is heated to 45-55°C. Graphite-supported silver nanowires are added, the mixture is stirred and maintained at this temperature, filtered, washed, and dried to obtain a sodium oleate-modified filler. S2: Take acrylic acid, methyl methacrylate, methyl acrylate, allyltrimethylammonium chloride, hydroxyethyl methacrylate, styrene, butyl acrylate, and di-tert-amyl peroxide, disperse them evenly to obtain a mixed monomer; take di-tert-amyl peroxide, vinyl silicone oil, and sodium oleate modified filler, add the mixed solvent and stir evenly, heat to 140-145°C and keep warm for 20-30 minutes, add the mixed monomer dropwise, cool to 80-85°C, add ethanedithiol and azobisisobutyronitrile, keep warm for 2-3 hours, and remove the solvent to obtain nanosilver A; S3: Take isocyanate-terminated polyurethane prepolymer as a template, adjust the pH to 4-6, add AgNO3 aqueous solution, stir evenly, and then add ascorbic acid dropwise under inert gas protection to obtain nanosilver B; S4: taking polyurethane acrylate, polyacrylate, acetone, photoinitiator, nanosilver A, and nanosilver B, and mixing them evenly to obtain a nanosilver coating; The nano silver coating comprises the following raw materials, calculated by mass: 20-25 parts of polyurethane acrylate, 15-20 parts of polyacrylate, 30-40 parts of acetone, 0.1-0.2 parts of photoinitiator, 1-2 parts of nano silver A, and 1-2 parts of nano silver B.

2. The method for preparing a nano silver coating for low-temperature and high-humidity thawing equipment according to claim 1, characterized in that: The sodium oleate modified filler includes the following raw materials, calculated in parts by mass: 0.4-0.6 parts of sodium oleate, 200-400 parts of water, and 4-6 parts of graphite-supported nanosilver wires; the nanosilver A includes the following raw materials, calculated in parts by mass: 6-8 parts of acrylic acid, 2-3 parts of methyl methacrylate, 2-3 parts of methyl acrylate, 4-5 parts of allyltrimethylammonium chloride, 8-10 parts of hydroxyethyl methacrylate, 3-4 parts of styrene, 10-12 parts of butyl acrylate, 80-100 parts of a mixed solvent, 8-12 parts of vinyl silicone oil, 80-100 parts of sodium oleate modified filler, 0.5-0.8 parts of ethanedithiol, and 0.2-0.3 parts of azobisisobutyronitrile.

3. The method for preparing a nano silver coating for low-temperature and high-humidity thawing equipment according to claim 1, characterized in that: In the nanosilver B, the mass ratio of the template, ascorbic acid and silver nitrate is (20-30): (8-10): (1-2).

4. The method for preparing a nano silver coating for low-temperature and high-humidity thawing equipment according to claim 1, characterized in that: The preparation of the isocyanate-terminated polyurethane prepolymer comprises the following steps: taking polyethylene glycol, castor oil, dihydroxybenzoic acid, trimethylolpropane, and acetone, stirring uniformly, adding isophorone diisocyanate and triphenylmethane triisocyanate after the temperature reaches 68-70°C, dropping a tin catalyst, and stirring for 3-4 hours to obtain the isocyanate-terminated polyurethane prepolymer.

5. The method for preparing a nano silver coating for low-temperature and high-humidity thawing equipment according to claim 4, characterized in that: The isocyanate-terminated polyurethane prepolymer includes the following raw materials, calculated by mass: 13-15 parts of polyethylene glycol, 3-4 parts of castor oil, 2-3 parts of dihydroxybenzoic acid, 2-3 parts of trimethylolpropane, 25-30 parts of acetone, 10-12 parts of isophorone diisocyanate, 4-6 parts of triphenylmethane triisocyanate, and 0.2-0.4 parts of a tin catalyst.

6. The method for preparing a nano silver coating for low-temperature and high-humidity thawing equipment according to claim 1, characterized in that: The preparation of the polyurethane acrylate comprises the following steps: Take the isocyanate-terminated polyurethane prepolymer, raise the temperature to 60-70°C, add hydroxyethyl methacrylate, stir and react until the -NCO content reaches the theoretical end point, stop the reaction, and remove the solvent by rotary evaporation to obtain polyurethane acrylate; The polyurethane acrylate comprises the following raw materials, calculated by weight: 10 to 15 parts of isocyanate-terminated polyurethane prepolymer and 2 to 3 parts of hydroxyethyl methacrylate.

7. The method for preparing a nano silver coating for low-temperature and high-humidity thawing equipment according to claim 1, characterized in that: The preparation of the graphite-supported silver nanowires comprises the following steps: Graphite was added to ethanol and ultrasonically dispersed to obtain a graphite dispersion; the graphite dispersion was heated to 150-160°C and kept warm for 10-15 minutes, polyvinyl pyrrolidone was added, and the mixture was heated for 20-30 minutes, 0.2 mmol / L CuCl2 aqueous solution and 0.2 mmol / L AgNO3 aqueous solution were added, and the mixture was stirred for 5-8 minutes, 3 mmol / L AgNO3 aqueous solution was added, and the mixture was stirred for 20-30 minutes, filtered, washed, and dried to obtain graphite-loaded silver nanowires; The graphite dispersion includes the following raw materials, calculated by mass: 2 to 3 parts of graphite and 150 to 200 parts of ethanol; the graphite-loaded nanosilver wires include the following raw materials, calculated by mass: 100 parts of graphite dispersion, 2 to 3 parts of polyvinyl pyrrolidone, 10 to 12 parts of a 0.2 mmol / L CuCl2 aqueous solution, 20 to 25 parts of a 0.2 mmol / L AgNO3 aqueous solution, and 10 to 15 parts of a 3 mmol / L AgNO3 aqueous solution.

8. The method for preparing a nano silver coating for low-temperature and high-humidity thawing equipment according to claim 1, characterized in that: The curing conditions of the nano silver coating are: temperature 45-55°C, 800-1000 mj / cm 2 Expose to ultraviolet light until film is formed.

9. The nano-silver coating prepared according to the method for preparing a nano-silver coating for low-temperature and high-humidity thawing equipment according to any one of claims 1 to 8.

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