Antibacterial stainless steel sheet for refrigerator lining and method for manufacturing the same

Abstract

The present application relates to the field of stainless steel material, and particularly relates to an antibacterial stainless steel plate for refrigerator lining and a preparation method thereof. The present application first prepares a stainless steel plate by adding stainless steel alloy powder. Then, the stainless steel plate is sequentially polished, ultrasonically cleaned, dried, laser etched, and cleaned again to obtain a pretreated stainless steel plate. Then, the pretreated stainless steel plate is immersed in a mesoporous polydopamine immersion liquid and reacted in the dark to obtain an antibacterial adhesion layer. Then, polyurethane-acrylic antibacterial paint is coated onto the surface of the stainless steel plate, and photocured to obtain a finished product. The finished product prepared by the present application has good antibacterial ability, and the coating can be firmly attached to the substrate, so the present application has a wide application prospect in the field of stainless steel material.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of stainless steel materials, in particular to an antibacterial stainless steel plate for refrigerator lining and a preparation method thereof. BACKGROUND

[0002] In the field of modern household appliances, stainless steel plates for refrigerator lining are playing an irreplaceable value with their unique advantages. From a practical point of view, stainless steel plates have excellent durability. As a long-term household appliance, the internal environment of a refrigerator is complex and will come into contact with various food and beverage juices. The corrosion resistance of stainless steel material is strong, which can effectively resist the erosion of these liquids and ensure that the refrigerator lining does not rust or deform during long-term use, greatly extending the service life of the refrigerator. Moreover, the surface of stainless steel is smooth and easy to clean. Just wipe it with a damp cloth to remove stains and keep the interior of the refrigerator clean, providing a good environment for food storage. In industrial production, stainless steel plates are easy to process and can be made into various shapes and sizes of lining according to the design requirements of the refrigerator, improving production efficiency and reducing production costs. Moreover, stainless steel materials can be recycled, which meets the concept of sustainable development and reduces the pressure on the environment.

[0003] However, the refrigerator is a place for storing food, and the internal environment is humid and suitable for temperature, which is easy to breed bacteria. If the stainless steel plate does not have good antibacterial properties, bacteria will multiply on its surface in large numbers and contaminate the stored food. Eating food contaminated by bacteria may cause various diseases and harm human health. Therefore, it is necessary to provide a stainless steel plate with antibacterial properties to effectively inhibit the growth and reproduction of bacteria and reduce the risk of food contamination, providing a safe food storage environment for consumers. Generally, preparing an antibacterial coating on the surface of a stainless steel plate is a common technical means to improve antibacterial properties, but in the humid environment of a refrigerator, the coating is prone to peeling. This not only affects the appearance of the refrigerator lining, making the refrigerator look old and unattractive, but also reduces the corrosion resistance of the stainless steel plate, shortening its service life. Therefore, it is necessary to improve the adhesion strength of the surface coating to ensure that the coating is firmly attached to the surface of the stainless steel plate for a long time and continuously plays its due role.

[0004] In order to overcome the defects of the prior art, the present application provides an antibacterial stainless steel plate for refrigerator lining and a preparation method thereof. SUMMARY

[0005] The purpose of the present application is to provide an antibacterial stainless steel plate for refrigerator lining and a preparation method thereof to solve the problems existing in the prior art.

[0006] To achieve the above-mentioned purpose, the present application provides the following technical solutions:

[0007] The application discloses a preparation method of an antibacterial stainless steel plate for refrigerator lining.

[0008] Step one: the stainless steel alloy powder is sequentially subjected to packaging welding, forging, hot rolling and forming processing to obtain a stainless steel plate; and then the stainless steel plate is sequentially subjected to polishing, ultrasonic cleaning, drying, laser etching and cleaning again to obtain a pretreated stainless steel plate;

[0009] Step two: mesoporous polydopamine nanoparticles are added into a Tris-HCl buffer solution with a pH of 8.5-9.0 to obtain a mesoporous polydopamine dipping solution with a concentration of 3-5 mg / mL; and then the pretreated stainless steel plate is immersed in the mesoporous polydopamine dipping solution and reacts at 25-30 DEG C in the dark for 25-30 h to obtain an antibacterial adhesion layer.

[0010] Step three: under a nitrogen environment, polypropylene glycol and polycaprolactone diol are mixed and stirred at 55-60 DEG C for 20-30 min; then isophorone diisocyanate and dibutyl tin dilaurate are added, the temperature is increased to 90-95 DEG C, and the stirring reaction is continued for 2.0-2.5 h; then the temperature is decreased to 45-50 DEG C, and a blocking agent, i.e., hydroxyethyl methacrylate, is added and the reaction is continued for 2-3 h to obtain a vinyl-terminated polyurethane; then the vinyl-terminated polyurethane, acrylic modified chitosan, acrylic modified tannic acid and acrylated quaternary ammonium salt are mixed and uniformly stirred, a photoinitiator, i.e., 2-hydroxy-2-methyl-1-phenyl-1-propanone, is added, and the stirring is continued in the dark for 10-20 min to obtain a polyurethane-acrylic antibacterial coating; the polyurethane-acrylic antibacterial coating is coated on the surface of the stainless steel plate obtained in step two, and the light curing is carried out at a wavelength of 250-260 nm for 5-7 min to obtain an antibacterial layer, which is the finished product.

[0011] More preferably, in step one, the laser etching parameters are as follows: the scanning power is 15-20 W, the scanning speed is 250-350 mm / s, and the scanning interval is 35-40 mu m.

[0012] More preferably, in step one, the content of each component of the stainless steel alloy powder is as follows: in terms of mass fraction, C is 0.01-0.08%, B is 0.5-1.5%, Si is 0.5-0.7%, Mn is 1.0-1.5%, P is 0.0025-0.035%, S is 0.020-0.025%, Ni is 12.0-15.0%, Cr is 18.0-20.0%, N is 0.05-0.07%, O is 0.003-0.004%, and the balance is Fe and inevitable impurities.

[0013] More preferably, in step two, the preparation process of the mesoporous polydopamine nanoparticles is as follows: Pluronic F-127 and 1,3,5-trimethylbenzene are sequentially added to an ethanol aqueous solution, an emulsion is obtained by ultrasonic dispersion, and then magnetic stirring is performed for 30-40 min; then Tris-HCl aqueous solution and dopamine hydrochloride are sequentially added, and the pH is adjusted to 8.5-8.7; reaction is performed at 25-30℃ in the dark for 25-30 h; after the reaction is completed, the solid nanoparticles are collected at 3-5℃; then ultrasonic cleaning, centrifugal collection, deionized water washing, and freeze-drying are performed to obtain the mesoporous polydopamine nanoparticles.

[0014] More preferably, the reaction mass ratio of Pluronic F-127, 1,3,5-trimethylbenzene, Tris-HCl, and dopamine hydrochloride is (37-40):36:9:6.

[0015] More preferably, in step three, when the vinyl-terminated polyurethane is prepared, the reaction mass ratio of polypropylene glycol, polycaprolactone diol, isophorone diisocyanate, and hydroxyethyl methacrylate is 3:(1.0-1.6):2:1.

[0016] More preferably, in step three, the content of each component of the polyurethane-acrylic antibacterial coating is as follows: 60-70% vinyl-terminated polyurethane, 15-20% acrylated chitosan, 10-15% acrylated quaternary ammonium salt, 6-10% acrylated tannic acid, and the rest is photoinitiator 2-hydroxy-2-methyl-1-phenyl-1-propanone; the coating thickness is 20-30 μm.

[0017] More preferably, the preparation process of the acrylated chitosan is as follows: chitosan and triethylamine are added to tetrahydrofuran, and then glycidyl methacrylate is added dropwise; after the dropwise addition is completed, reflux reaction is performed at 60-65℃ for 3-4 h; then deionized water is added dropwise, and reaction is continued for 3-4 h; then the temperature is lowered to 20-25℃, and reaction is continued for 10-12 h; after the reaction is completed, centrifugation, washing, and vacuum drying are performed to obtain the acrylated chitosan; wherein the reaction mass ratio of chitosan, triethylamine, glycidyl methacrylate, and deionized water is 3:10:(15-17):0.5.

[0018] More preferably, the preparation process of the acrylated tannic acid is as follows: tannic acid, ethyl acetate, and butyl acetate are mixed and dissolved by heating, then triphenylphosphine and hydroquinone are added, and then glycidyl methacrylate is added dropwise; stirring reaction is performed at 95-100℃ for 25-30 h; after the reaction is completed, drying is performed to obtain the acrylated tannic acid; wherein the reaction mass ratio of tannic acid and glycidyl methacrylate is 1.5:(4-5).

[0019] More preferably, the preparation process of the acrylated quaternary ammonium salt is as follows: 2-dimethylaminomethyl acrylate and chlorohexadecane are sequentially added into acetonitrile, and stirred at 50-55 DEG C for 5-6 hours; after the reaction is completed, rotary evaporation and drying are performed to obtain the acrylated quaternary ammonium salt; wherein the mass ratio of 2-dimethylaminomethyl acrylate to chlorohexadecane is 16:(31-34).

[0020] The beneficial effects of the present application are as follows:

[0021] The present application is characterized in that, in step one, the stainless steel plate is sequentially polished, ultrasonically cleaned, dried, laser etched, and cleaned again to obtain a pretreated stainless steel plate. This step forms micro convexities and concavities on the surface of the stainless steel plate by laser etching, so that the coating material can penetrate into the rough structure during the subsequent coating operation, greatly increasing the contact area between the coating and the surface of the stainless steel plate, thereby significantly improving the mechanical interlocking force of the coating and making the coating more firmly adhere to the stainless steel plate. In addition, the coating material on the rough surface will not agglomerate or flow unevenly due to surface tension and other factors, thereby ensuring the uniformity of the coating thickness and the stability of the coating quality.

[0022] The present application is characterized in that, in step two, mesoporous polydopamine nanoparticles are added to Tris-HCl buffer solution to obtain a mesoporous polydopamine impregnating solution; and the pretreated stainless steel plate is then immersed in the mesoporous polydopamine impregnating solution and subjected to light-shielded reaction to obtain an antibacterial adhesion layer. The antibacterial adhesion layer formed on the surface of the stainless steel plate generally has a micro-nano topological structure. Many sharp protrusions and edges of these structures are similar in size or smaller than bacteria, so when bacteria adhere to the surface of the material, the micro-nano structure will directly contact the bacteria, generating extremely high local pressure, piercing the bacterial cell membrane, and causing the bacteria to die. In addition, the polydopamine molecule contains a large number of functional groups such as catechol and amino groups. In the Tris-HCl buffer solution environment, these functional groups can chemically react with the metal atoms on the surface of the pretreated stainless steel plate, allowing the polydopamine to firmly adhere to the surface of the stainless steel plate and form a stable antibacterial adhesion layer. Therefore, the formed antibacterial adhesion layer has double advantages. The good physical antibacterial property can effectively inhibit the growth and reproduction of bacteria on the surface of the stainless steel plate, reducing bacterial contamination; and the good adhesion ensures that the antibacterial layer can be firmly attached to the stainless steel plate and will not easily fall off, thereby prolonging the durability of the antibacterial effect and improving the antibacterial performance and service life of the stainless steel plate in various environments.

[0023] The application is characterized in that, in step three, the vinyl-terminated polyurethane is prepared by adding polypropylene glycol, polycaprolactone diol, isophorone diisocyanate and hydroxyethyl methacrylate. The acrylic acid-modified chitosan is obtained by ring-opening reaction through adding chitosan, triethylamine and glycidyl methacrylate. The acrylic acid-modified tannic acid is obtained by ring-opening reaction through adding tannic acid, glycidyl methacrylate, triphenylphosphine and hydroquinone. The acrylic quaternary ammonium salt is obtained by nucleophilic substitution reaction through adding 2-dimethylamino methacrylate ethyl ester and chlorohexadecane. Then, the three substances with C=C and antibacterial structure (tannic acid antibacterial structure, chitosan antibacterial structure and quaternary ammonium salt antibacterial structure) and the vinyl-terminated polyurethane are mixed, and copolymerization occurs under the initiation of the photoinitiator 2-hydroxy-2-methyl-1-phenyl-1-propanone to obtain the antibacterial layer.

[0024] The tannic acid antibacterial structure, the chitosan antibacterial structure and the quaternary ammonium salt antibacterial structure in the antibacterial layer can play a synergistic antibacterial effect. Different antibacterial components act on different targets of bacteria, and can more comprehensively destroy the physiological functions of bacteria. The chitosan and the quaternary ammonium salt mainly interact with the surface of bacteria through electrostatic interaction to destroy the cell membrane; and the tannic acid can further combine with the proteins and metal ions in the cells to interfere with the metabolism and gene expression of bacteria; the multi-target action mode can greatly improve the antibacterial efficiency and enhance the antibacterial performance of the antibacterial layer. In addition, in the process of photocuring, the vinyl-terminated polyurethane copolymerizes with the acrylic acid-modified chitosan, the acrylic quaternary ammonium salt and the acrylic acid-modified tannic acid to form a stable three-dimensional network structure, so that the antibacterial components are fixed in the network structure and cannot easily flow out. At the same time, the network structure can play a role in slow-release of the antibacterial components, so that the antibacterial components can be continuously and slowly released into the surrounding environment to maintain long-term antibacterial effect. DETAILED DESCRIPTION

[0025] The technical solutions in the embodiments of the application will be clearly and completely described below. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the application.

[0026] Raw material sources:

[0027] Pluronic F-127 was provided by Sigma Reagent Co., Ltd.; polypropylene glycol was provided by Nantong Renda Chemical Co., Ltd., and the model number was PPG4000; polycaprolactone diol was provided by Hubei Darli Chemical Co., Ltd., and the model number was Darl-1; chitosan, Mw=200kDa, and the degree of deacetylation was 85%.

[0028] Embodiment 1: Step one: the stainless steel alloy powder is sequentially subjected to packaging welding, forging, hot rolling, and forming processing to obtain a stainless steel plate; the stainless steel plate is sequentially subjected to polishing, ultrasonic cleaning, drying, laser etching, and cleaning again to obtain a pretreated stainless steel plate; the laser etching parameters are as follows: a scanning power of 20 W, a scanning speed of 350 mm / s, and a scanning interval of 40 μm;

[0029] The content of each component of the stainless steel alloy powder is as follows: C: 0.02%, B: 1%, Si: 0.6%, Mn: 1.2%, P: 0.003%, S: 0.022%, Ni: 13%, Cr: 19%, N: 0.06%, O: 0.0035%, and the balance of Fe and unavoidable impurities;

[0030] Step two: Pluronic F-127 and 1,3,5-trimethylbenzene are sequentially added to an aqueous ethanol solution, and an emulsion is obtained by ultrasonic dispersion, followed by magnetic stirring for 40 min; Tris-HCl aqueous solution and dopamine hydrochloride are sequentially added, and the pH is adjusted to 8.7; reaction is carried out at 30°C for 30 h in the dark; after the reaction is completed, the solid nanoparticles are collected at 5°C; the nanoparticles are then subjected to ultrasonic cleaning, centrifugal collection, deionized water washing, and freeze-drying to obtain mesoporous polydopamine nanoparticles; the reaction mass ratio of Pluronic F-127, 1,3,5-trimethylbenzene, Tris-HCl, and dopamine hydrochloride is 38:36:9:6;

[0031] The mesoporous polydopamine nanoparticles are added to Tris-HCl buffer solution with a pH of 9.0 to obtain a mesoporous polydopamine impregnating solution with a concentration of 5 mg / mL; the pretreated stainless steel plate is then immersed in the mesoporous polydopamine impregnating solution, and reaction is carried out at 30°C for 30 h in the dark to obtain an antibacterial adhesion layer;

[0032] Step three: under a nitrogen atmosphere, polypropylene glycol and polycaprolactone diol are mixed and stirred at 60°C for 30 min; isophorone diisocyanate and dibutyl tin dilaurate are then added; the temperature is raised to 95°C, and the stirring reaction is continued for 2.5 h; the temperature is then lowered to 50°C, and the capping agent hydroxyethyl methacrylate is added for further reaction for 3 h to obtain a vinyl-terminated polyurethane; when preparing the vinyl-terminated polyurethane, the reaction mass ratio of polypropylene glycol, polycaprolactone diol, isophorone diisocyanate, and hydroxyethyl methacrylate is 3:1.3:2:1;

[0033] The chitosan, triethylamine are added into tetrahydrofuran, after being fully stirred, glycidyl methacrylate is added dropwise, after the dropwise addition is completed, the reaction is carried out at 65 DEG C for 4 h, deionized water is added dropwise, and the reaction is continued for 4 h, then the temperature is lowered to 25 DEG C, and the reaction is continued for 12 h, after the reaction is completed, centrifugation, washing and vacuum drying are carried out, and the acrylic acid modified chitosan is obtained; wherein the mass ratio of chitosan, triethylamine, glycidyl methacrylate and deionized water is 3:10:16:0.5;

[0034] The tannic acid, ethyl acetate and butyl acetate are mixed, heated and dissolved, then triphenylphosphine and hydroquinone are added, stirred uniformly, then glycidyl methacrylate is added dropwise, and the reaction is carried out at 100 DEG C for 30 h, after the reaction is completed, drying is carried out, and the acrylic acid modified tannic acid is obtained; wherein the mass ratio of tannic acid and glycidyl methacrylate is 1.5:4.5;

[0035] The 2-dimethylaminomethyl acrylate and chlorohexadecane are added into acetonitrile in sequence, and the reaction is carried out at 55 DEG C for 6 h, after the reaction is completed, rotary evaporation and drying are carried out, and the acrylic acid quaternary ammonium salt is obtained; wherein the mass ratio of 2-dimethylaminomethyl acrylate and chlorohexadecane is 16:32;

[0036] Then 62% vinyl-terminated polyurethane, 17% acrylic acid modified chitosan, 12% acrylic acid modified tannic acid and 7% acrylic acid quaternary ammonium salt are mixed, 2% photoinitiator 2-hydroxy-2-methyl-1-phenyl-1-propanone is added, and the mixture is stirred uniformly in dark for 20 min, and the polyurethane-acrylic acid antibacterial coating is obtained; the polyurethane-acrylic acid antibacterial coating is coated on the surface of the stainless steel plate obtained in step two, and light curing is carried out at 260 nm for 7 min, and the antibacterial layer with a thickness of 25 μm is obtained, which is the finished product.

[0037] Example 2: Step one: the stainless steel alloy powder is sequentially subjected to packaging welding, forging, hot rolling and forming processing, and the stainless steel plate is obtained; then the stainless steel plate is sequentially subjected to polishing, ultrasonic cleaning, drying, laser etching and cleaning again, and the pretreated stainless steel plate is obtained; the laser etching parameters are as follows: the scanning power is 17 W, the scanning speed is 300 mm / s, and the scanning interval is 37 μm;

[0038] The content of each component of the stainless steel alloy powder is as follows: in terms of mass fraction, C: 0.02%, B: 1%, Si: 0.6%, Mn: 1.2%, P: 0.003%, S: 0.022%, Ni: 13%, Cr: 19%, N: 0.06%, O: 0.0035%, and the balance is Fe and unavoidable impurities;

[0039] Step two: Pluronic F-127, 1, 3, 5-trimethylbenzene were added to the aqueous ethanol solution in turn, and an emulsion was obtained by ultrasonic dispersion, then magnetic stirring for 35 min, then Tris-HCl aqueous solution, dopamine hydrochloride were added in turn, and the pH was adjusted to 8.6, then reaction at 27℃ for 27h in the dark, then the solid nanoparticles were collected at 4℃ after the reaction was completed, then washed by ultrasonic, centrifuged, washed with deionized water, and freeze-dried to obtain mesoporous polydopamine nanoparticles; the reaction mass ratio of Pluronic F-127, 1, 3, 5-trimethylbenzene, Tris-HCl, dopamine hydrochloride was 38:36:9:6;

[0040] The mesoporous polydopamine nanoparticles were added to the Tris-HCl buffer solution with pH of 8.7 to obtain a mesoporous polydopamine impregnating solution with a concentration of 4mg / mL; then the pretreated stainless steel plate was immersed in the mesoporous polydopamine impregnating solution, and reacted at 27℃ for 27h in the dark to obtain an antibacterial adhesion layer;

[0041] Step three: under the nitrogen environment, polypropylene glycol and polycaprolactone diol were mixed, stirred at 57℃ for 25min, then isophorone diisocyanate and dibutyl tin dilaurate were added, the temperature was raised to 92℃ and the stirring was continued for 2.3h, then the temperature was lowered to 47℃, and the end-capping agent hydroxyethyl methacrylate was added and the reaction was continued for 2.5h to obtain the vinyl-terminated polyurethane; when preparing the vinyl-terminated polyurethane, the reaction mass ratio of polypropylene glycol, polycaprolactone diol, isophorone diisocyanate and hydroxyethyl methacrylate was 3:1.3:2:1;

[0042] Chitosan and triethylamine were added to tetrahydrofuran, then glycidyl methacrylate was added dropwise in turn after stirring, then the reaction was carried out at 62℃ for 3.5h after reflux, then deionized water was added dropwise and the reaction was continued for 3.5h, then the temperature was lowered to 22℃ and the reaction was continued for 11h, then the reaction was completed by centrifugation, washing and vacuum drying to obtain the acrylic acid modified chitosan; the reaction mass ratio of chitosan, triethylamine, glycidyl methacrylate and deionized water was 3:10:16:0.5;

[0043] Tannic acid, ethyl acetate and butyl acetate were mixed, dissolved by heating, then triphenylphosphine and hydroquinone were added, stirred uniformly, then glycidyl methacrylate was added dropwise, and the reaction was carried out at 97℃ for 27h, then the reaction was completed by drying to obtain the acrylic acid modified tannic acid; the reaction mass ratio of tannic acid and glycidyl methacrylate was 1.5:4.5;

[0044] 2-Dimethylaminomethyl acrylate and chlorohexadecane were added to acetonitrile in turn, and the reaction was carried out at 52℃ for 5.5h, then the reaction was completed by rotary evaporation and drying to obtain the acrylated quaternary ammonium salt; the reaction mass ratio of 2-dimethylaminomethyl acrylate and chlorohexadecane was 16:32.

[0045] Then 62% of the vinyl-terminated polyurethane, 17% of the acrylic-modified chitosan, 12% of the acrylic-modified tannic acid, and 7% of the acrylated quaternary ammonium salt were mixed, stirred uniformly, and then 2% of the photoinitiator 2-hydroxy-2-methyl-1-phenyl-1-propanone was added, stirred in the dark for 15 min, to obtain the polyurethane-acrylic antibacterial coating; the polyurethane-acrylic antibacterial coating was coated onto the surface of the stainless steel plate obtained in step two, and photocured at a wavelength of 255 nm for 6 min to obtain an antibacterial layer with a thickness of 25 μm, which was the finished product.

[0046] Example 3: Step one: the stainless steel alloy powder was sequentially subjected to packaging welding, forging, hot rolling, and forming processing to obtain a stainless steel plate; the stainless steel plate was then sequentially subjected to polishing, ultrasonic cleaning, drying, laser etching, and cleaning again to obtain a pretreated stainless steel plate; the laser etching parameters were as follows: scanning power was 15 W, scanning speed was 250 mm / s, and scanning interval was 35 μm;

[0047] The content of each component of the stainless steel alloy powder was as follows: C: 0.02%, B: 1%, Si: 0.6%, Mn: 1.2%, P: 0.003%, S: 0.022%, Ni: 13%, Cr: 19%, N: 0.06%, O: 0.0035%, and the balance was Fe and unavoidable impurities;

[0048] Step two: Pluronic F-127 and 1,3,5-trimethylbenzene were sequentially added to an aqueous ethanol solution, and an emulsion was obtained by ultrasonic dispersion, followed by magnetic stirring for 30 min; then Tris-HCl aqueous solution and dopamine hydrochloride were sequentially added, and the pH was adjusted to 8.5; the mixture was reacted at 25°C in the dark for 25 h; after the reaction was completed, the solid nanoparticles were collected at 3°C, and then subjected to ultrasonic cleaning, centrifugal collection, deionized water washing, and freeze-drying to obtain mesoporous polydopamine nanoparticles; the reaction mass ratio of Pluronic F-127, 1,3,5-trimethylbenzene, Tris-HCl, and dopamine hydrochloride was 38:36:9:6;

[0049] The mesoporous polydopamine nanoparticles were added to Tris-HCl buffer solution with a pH of 8.5 to obtain a mesoporous polydopamine impregnating solution with a concentration of 3 mg / mL; the pretreated stainless steel plate was then immersed in the mesoporous polydopamine impregnating solution, and reacted at 25°C in the dark for 25 h to obtain an antibacterial adhesion layer;

[0050] Step three: under the environment of nitrogen, polypropylene glycol, polycaprolactone diol were mixed and stirred at 55℃ for 20 min, then isophorone diisocyanate, dibutyl tin dilaurate were added, the temperature was raised to 90℃ and the reaction was continued for 2 h, then the temperature was lowered to 45℃, and the end-capping agent hydroxyethyl methacrylate was added and the reaction was continued for 2 h, to obtain the vinyl-terminated polyurethane; when preparing the vinyl-terminated polyurethane, the mass ratio of polypropylene glycol, polycaprolactone diol, isophorone diisocyanate, and hydroxyethyl methacrylate was 3:1.3:2:1;

[0051] Chitosan and triethylamine were added to tetrahydrofuran, and after being stirred well, glycidyl methacrylate was added dropwise, then after the dropwise addition was completed, the reaction was carried out at 60℃ for 3 h, deionized water was added dropwise and the reaction was continued for 3 h, then the temperature was lowered to 20℃ and the reaction was continued for 10 h, after the reaction was completed, centrifugation, washing, and vacuum drying were carried out, to obtain the acrylic acid modified chitosan; wherein the mass ratio of chitosan, triethylamine, glycidyl methacrylate, and deionized water was 3:10:16:0.5;

[0052] Tannic acid, ethyl acetate, and butyl acetate were mixed and dissolved by heating, then triphenylphosphine and hydroquinone were added, the mixture was stirred uniformly, then glycidyl methacrylate was added dropwise, and the reaction was carried out at 95℃ for 25 h, after the reaction was completed, drying was carried out, to obtain the acrylic acid modified tannic acid; wherein the mass ratio of tannic acid and glycidyl methacrylate was 1.5:4.5;

[0053] 2-Dimethylaminomethyl acrylate and chlorohexadecane were added to acetonitrile in sequence, and the reaction was carried out at 50℃ for 5 h, after the reaction was completed, rotary evaporation and drying were carried out, to obtain the quaternary ammonium salt of acrylic acid; wherein the mass ratio of 2-dimethylaminomethyl acrylate and chlorohexadecane was 16:32;

[0054] Then 62% of the vinyl-terminated polyurethane, 17% of the acrylic acid modified chitosan, 12% of the acrylic acid modified tannic acid, and 7% of the quaternary ammonium salt of acrylic acid were mixed, 2% of the photoinitiator 2-hydroxy-2-methyl-1-phenyl-1-propanone was added, and the mixture was stirred uniformly in the dark for 10 min, to obtain the polyurethane-acrylic acid antibacterial coating; the polyurethane-acrylic acid antibacterial coating was coated onto the surface of the stainless steel plate obtained in step two, and photocuring was carried out at a wavelength of 250 nm for 5 min, to obtain an antibacterial layer with a thickness of 25μm, which was the finished product.

[0055] Comparative example 1: the pretreatment of the stainless steel plate was removed, and the rest was the same as example 1, and the specific steps were as follows: step one: the stainless steel alloy powder was subjected to encapsulation welding, forging, hot rolling, and forming processing in sequence, to obtain the stainless steel plate;

[0056] The content of each component of the stainless steel alloy powder is as follows: C: 0.02%, B: 1%, Si: 0.6%, Mn: 1.2%, P: 0.003%, S: 0.022%, Ni: 13%, Cr: 19%, N: 0.06%, O: 0.0035%, and the balance of Fe and inevitable impurities, by mass fraction;

[0057] Step two: Pluronic F-127 and 1,3,5-trimethylbenzene were sequentially added to an aqueous ethanol solution, and an emulsion was obtained by ultrasonic dispersion, and then magnetic stirring was performed for 40 min; Tris-HCl aqueous solution and dopamine hydrochloride were sequentially added, and the pH was adjusted to 8.7; reaction was carried out at 30℃ for 30 h in the dark; after the reaction was completed, the solid nanoparticles were collected at 5℃; and then ultrasonic cleaning, centrifugal collection, deionized water washing, and freeze-drying were performed to obtain mesoporous polydopamine nanoparticles; the reaction mass ratio of Pluronic F-127, 1,3,5-trimethylbenzene, Tris-HCl, and dopamine hydrochloride was 38:36:9:6;

[0058] The mesoporous polydopamine nanoparticles were added to Tris-HCl buffer solution with a pH of 9.0 to obtain a mesoporous polydopamine impregnating solution with a concentration of 5 mg / mL; and then the stainless steel plate was immersed in the mesoporous polydopamine impregnating solution, and reaction was carried out at 30℃ for 30 h in the dark to obtain an antibacterial adhesion layer;

[0059] Step three: under a nitrogen environment, polypropylene glycol and polycaprolactone diol were mixed and stirred at 60℃ for 30 min; isophorone diisocyanate and dibutyltin dilaurate were added; the temperature was increased to 95℃ and the stirring was continued for 2.5 h; then the temperature was decreased to 50℃, and the capping agent hydroxyethyl methacrylate was added and the reaction was continued for 3 h to obtain a vinyl-terminated polyurethane; when preparing the vinyl-terminated polyurethane, the reaction mass ratio of polypropylene glycol, polycaprolactone diol, isophorone diisocyanate, and hydroxyethyl methacrylate was 3:1.3:2:1;

[0060] Chitosan and triethylamine were added to tetrahydrofuran, and then glycidyl methacrylate was added dropwise; after the dropwise addition was completed, reflux reaction was carried out at 65℃ for 4 h; deionized water was added dropwise and the reaction was continued for 4 h; then the temperature was decreased to 25℃ and the reaction was continued for 12 h; after the reaction was completed, centrifugal collection, washing, and vacuum drying were performed to obtain acrylic acid-modified chitosan; the reaction mass ratio of chitosan, triethylamine, glycidyl methacrylate, and deionized water was 3:10:16:0.5;

[0061] The tannic acid, ethyl acetate and butyl acetate are mixed, heated and dissolved, then triphenylphosphine and hydroquinone are added, stirred uniformly, then glycidyl methacrylate is added dropwise, stirred at 100℃ for 30h, after the reaction is completed, dried to obtain the acrylic modified tannic acid; wherein the reaction mass ratio of tannic acid and glycidyl methacrylate is 1.5:4.5;

[0062] The 2-dimethylaminomethyl acrylate and chlorohexadecane are sequentially added to acetonitrile, stirred at 55℃ for 6h, after the reaction is completed, rotary evaporation and drying to obtain the quaternary ammonium salt of acrylation; wherein the reaction mass ratio of 2-dimethylaminomethyl acrylate and chlorohexadecane is 16:32;

[0063] Then 62% vinyl-terminated polyurethane, 17% acrylic modified chitosan, 12% acrylic modified tannic acid, 7% quaternary ammonium salt of acrylation are mixed, stirred uniformly, then 2% photoinitiator 2-hydroxy-2-methyl-1-phenyl-1-propanone is added, stirred in dark for 20min to obtain the polyurethane-acrylic antibacterial coating; the polyurethane-acrylic antibacterial coating is coated on the surface of the stainless steel plate obtained in step two, light cured at 260nm wavelength for 7min to obtain an antibacterial layer with a thickness of 25μm, which is the finished product.

[0064] Comparative Example 2: the antibacterial adhesion layer is removed, and the rest is the same as Example 1, the specific steps are as follows: step one: the stainless steel alloy powder is sequentially subjected to packaging welding, forging, hot rolling and forming processing to obtain a stainless steel plate; then the stainless steel plate is sequentially polished, ultrasonically cleaned, dried, laser etched and cleaned again to obtain a pretreated stainless steel plate; the laser etching parameters are: scanning power is 20W, scanning speed is 350mm / s, and scanning interval is 40μm;

[0065] The content of each component of the stainless steel alloy powder is as follows: in mass fraction, C: 0.02%, B: 1%, Si: 0.6%, Mn 1.2%, P: 0.003%, S: 0.022%, Ni: 13%, Cr: 19%, N: 0.06%, O: 0.0035%, and the balance is Fe and unavoidable impurities;

[0066] Step two: under nitrogen environment, polypropylene glycol and polycaprolactone diol are mixed, stirred at 60℃ for 30min, then isophorone diisocyanate and dibutyltin dilaurate are added, heated to 95℃ and continue to stir for 2.5h, then cooled to 50℃, and add the end-capping agent hydroxyethyl methacrylate to continue to react for 3h to obtain the vinyl-terminated polyurethane; when preparing the vinyl-terminated polyurethane, the reaction mass ratio of polypropylene glycol, polycaprolactone diol, isophorone diisocyanate and hydroxyethyl methacrylate is 3:1.3:2:1;

[0067] The chitosan, triethylamine are added into tetrahydrofuran, after fully stirring, glycidyl methacrylate is added dropwise, after the dropwise addition is completed, the reaction is carried out at 65 DEG C for 4 h, deionized water is added dropwise and the reaction is continued for 4 h, then the temperature is lowered to 25 DEG C and the reaction is continued for 12 h, after the reaction is completed, centrifugation, washing and vacuum drying are carried out, and the acrylic modified chitosan is obtained; the mass ratio of chitosan, triethylamine, glycidyl methacrylate and deionized water is 3:10:16:0.5;

[0068] The tannic acid, ethyl acetate and butyl acetate are mixed, heated and dissolved, then triphenylphosphine and hydroquinone are added, stirred uniformly, then glycidyl methacrylate is added dropwise, and the reaction is carried out at 100 DEG C for 30 h, after the reaction is completed, drying is carried out, and the acrylic modified tannic acid is obtained; the mass ratio of tannic acid and glycidyl methacrylate is 1.5:4.5;

[0069] 2-Dimethylaminomethyl acrylate and chlorohexadecane are added into acetonitrile in sequence, and the reaction is carried out at 55 DEG C for 6 h, after the reaction is completed, rotary evaporation and drying are carried out, and the acrylic quaternary ammonium salt is obtained; the mass ratio of 2-dimethylaminomethyl acrylate and chlorohexadecane is 16:32;

[0070] Then 62% vinyl-terminated polyurethane, 17% acrylic modified chitosan, 12% acrylic modified tannic acid and 7% acrylic quaternary ammonium salt are mixed, 2% photoinitiator 2-hydroxy-2-methyl-1-phenyl-1-propanone is added, and the mixture is stirred uniformly in dark for 20 min, and the polyurethane-acrylic antibacterial coating is obtained; the polyurethane-acrylic antibacterial coating is coated on the surface of the pretreated stainless steel plate, and light curing is carried out at 260 nm for 7 min, and the antibacterial layer with a thickness of 25 μm is obtained, which is the finished product.

[0071] Comparative Example 3: The antibacterial layer is removed, and the rest is the same as in Example 1, and the specific steps are as follows: Step one: the stainless steel alloy powder is subjected to encapsulation welding, forging, hot rolling and forming processing in sequence, and the stainless steel plate is obtained; then the stainless steel plate is subjected to polishing, ultrasonic cleaning, drying, laser etching and cleaning in sequence, and the pretreated stainless steel plate is obtained; the laser etching parameters are as follows: scanning power is 20 W, scanning speed is 350 mm / s, and scanning interval is 40 μm;

[0072] The content of each component of the stainless steel alloy powder is as follows: in terms of mass fraction, C: 0.02%, B: 1%, Si: 0.6%, Mn: 1.2%, P: 0.003%, S: 0.022%, Ni: 13%, Cr: 19%, N: 0.06%, O: 0.0035%, and the balance is Fe and unavoidable impurities;

[0073] Step two: Pluronic F-127, 1,3,5-trimethylbenzene were added into the aqueous ethanol solution in turn, and an emulsion was obtained by ultrasonic dispersion, and then magnetic stirring was carried out for 40 min, and then Tris-HCl aqueous solution, dopamine hydrochloride were added in turn, and the pH was adjusted to 8.7, and then reaction was carried out at 30℃ for 30 h in the dark, and then the solid nanoparticles were collected at 5℃ after reaction, and then ultrasonic cleaning, centrifugal collection, deionized water washing and freeze drying were carried out, and then mesoporous polydopamine nanoparticles were obtained; the reaction mass ratio of Pluronic F-127, 1,3,5-trimethylbenzene, Tris-HCl and dopamine hydrochloride was 38:36:9:6;

[0074] The mesoporous polydopamine nanoparticles were added into Tris-HCl buffer solution with a pH of 9.0 to obtain a mesoporous polydopamine impregnating solution with a concentration of 5 mg / mL; and then the pretreated stainless steel plate was immersed in the mesoporous polydopamine impregnating solution, and reaction was carried out at 30℃ for 30 h in the dark to obtain an antibacterial adhesion layer, that is, a finished product.

[0075] Detection test:

[0076] Antibacterial performance test: E. coli suspension (concentration: 1×10 8 CFU / mL) was added dropwise to the surface of the finished product prepared in the application, and then a sterile glass slide was used for pressing to evenly spread the E. coli suspension on the surface of the finished product, and then culture was carried out at 30-40℃ for 2 h. PBS phosphate buffer was used to rinse the surface of the finished product and the glass slide, and then the rinsed E. coli suspension was diluted 10 times and inoculated in agar culture medium, and then culture was carried out at 30-40℃ for 20-24 h, and then the number of colonies was counted. A control group was set, and a stainless steel plate without any treatment was used, and the above steps were repeated, and then the number of colonies was counted, and the data of the experimental group and the control group were brought into the formula to calculate the antibacterial rate.

[0077] Adhesion test: the finished product prepared in the application was used as a test object, and an electronic universal testing machine was used for pull-off test to test the adhesion strength between the coating and the substrate. The results are as follows:

[0078] Antibacterial rate / % adhesion strength MPa ]]> Example 1 98.7 3.7 Example 2 98.5 3.7 Example 3 98.3 3.6 Comparative Example 1 94.7 3.3 Comparative Example 2 83.8 2.6 Comparative Example 3 77.9 3.1

[0079] Conclusion: the dosage of examples 1-3 is unchanged, and only part of the reaction parameters is modified. According to the experimental data, the performance of the sample does not change significantly.

[0080] Comparative Example 1: The pretreatment of the stainless steel plate was removed, and the rest was the same as Example 1. According to the experimental data, the adhesion strength was reduced to 3.3 MPa compared with Example 1. The analysis reason is that the pretreatment step of the stainless steel plate greatly increases the contact area between the coating and the surface of the stainless steel plate by forming a rough surface, thereby significantly improving the mechanical interlocking force of the coating, so that the coating is more firmly attached to the stainless steel plate. Therefore, after removing it, the adhesion strength is reduced.

[0081] Comparative Example 2: The antibacterial adhesive layer was removed, and the rest was the same as Example 1. According to the experimental data, the antibacterial rate was reduced to 83.8%, and the adhesion strength was reduced to 2.6 MPa compared with Example 1. The analysis reason is that the mesoporous polydopamine nanostructure of the antibacterial adhesive layer has good physical antibacterial properties and can effectively inhibit the growth and reproduction of bacteria on the surface of the stainless steel plate. It also has good adhesion and is not easy to fall off, so after removing it, the antibacterial rate increases and the adhesion strength decreases.

[0082] Comparative Example 3: The antibacterial layer was removed, and the rest was the same as Example 1. According to the experimental data, the antibacterial rate was reduced to 77.9%, and the adhesion strength was reduced to 3.1 MPa compared with Example 1. The analysis reason is that the antibacterial layer contains a stable three-dimensional network structure formed by a variety of antibacterial structures, so it has excellent antibacterial effect and antibacterial stability. Therefore, after removing it, the antibacterial rate is reduced.

[0083] It should be noted that in this paper, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between the entities or operations. Moreover, the terms "include", "contain" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process method article or equipment including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such process method article or equipment.

[0084] Finally, it should be noted that the above only describes the preferred embodiments of the present application and is not intended to limit the present application. Although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent replacements to some technical features. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method for preparing an antibacterial stainless steel plate for refrigerator lining, characterized in that: Includes the following steps: Step 1: The stainless steel alloy powder is sequentially packaged, welded, forged, hot-rolled, and formed to obtain a stainless steel plate; then the stainless steel plate is sequentially ground, ultrasonically cleaned, dried, laser-etched, and cleaned again to obtain a pre-treated stainless steel plate. Step 2: Add mesoporous polydopamine nanoparticles to Tris-HCl buffer solution with pH 8.5-9.0 to obtain a mesoporous polydopamine impregnation solution with a concentration of 3-5 mg / mL; then immerse the pretreated stainless steel plate in the mesoporous polydopamine impregnation solution and react at 25-30℃ in the dark for 25-30 h to obtain an antibacterial adhesion layer. Step 3: Under nitrogen atmosphere, mix polypropylene glycol and polycaprolactone glycol, stir at 55-60℃ for 20-30 min, then add isophorone diisocyanate and dibutyltin dilaurate, heat to 90-95℃ and continue stirring for 2.0-2.5 h, then cool to 45-50℃, add end-capping agent hydroxyethyl methacrylate and continue reaction for 2-3 h to obtain vinyl-terminated polyurethane; then mix vinyl-terminated polyurethane, acrylic-modified chitosan, acrylic-modified tannic acid, and acrylated quaternary ammonium salt, stir evenly, add photoinitiator 2-hydroxy-2-methyl-1-phenyl-1-propanone and stir in the dark for 10-20 min to obtain polyurethane-acrylic antibacterial coating; apply polyurethane-acrylic antibacterial coating to the surface of the stainless steel plate obtained in Step 2, and cure at 250-260 nm wavelength for 5-7 min to obtain antibacterial layer, i.e., finished product; The preparation process of acrylic acid modified chitosan is as follows: chitosan and triethylamine are added to tetrahydrofuran, stirred thoroughly, and then glycidyl methacrylate is added dropwise. After the addition is completed, the mixture is refluxed at 60-65℃ for 3-4 hours, then deionized water is added dropwise and the reaction continues for 3-4 hours. The temperature is then lowered to 20-25℃ and the reaction continues for 10-12 hours. After the reaction is completed, the mixture is centrifuged, washed, and vacuum dried to obtain acrylic acid modified chitosan. The mass ratio of chitosan, triethylamine, glycidyl methacrylate, and deionized water is 3:10:(15-17):0.

5. The preparation process of acrylic acid modified tannic acid is as follows: tannic acid, ethyl acetate, and butyl acetate are mixed, heated to dissolve, and then triphenylphosphine and hydroquinone are added. After stirring evenly, glycidyl methacrylate is added dropwise. The mixture is stirred at 95-100℃ for 25-30 hours. After the reaction is completed, it is dried to obtain acrylic acid modified tannic acid. The mass ratio of tannic acid to glycidyl methacrylate is 1.5:(4-5). The preparation process of acrylated quaternary ammonium salt is as follows: ethyl 2-dimethylaminomethacrylate and hexadecane chloroform are added to acetonitrile in sequence, and the mixture is stirred at 50-55℃ for 5-6 hours. After the reaction is completed, the mixture is rotary evaporated and dried to obtain acrylated quaternary ammonium salt; wherein the reaction mass ratio of ethyl 2-dimethylaminomethacrylate and hexadecane chloroform is 16:(31-34).

2. The method for preparing an antibacterial stainless steel plate for refrigerator lining according to claim 1, characterized in that: In step one, the laser etching parameters are: scanning power of 15-20W, scanning speed of 250-350mm / s, and scanning spacing of 35-40μm.

3. The method for preparing an antibacterial stainless steel plate for refrigerator lining according to claim 1, characterized in that: In step one, the content of each component of the stainless steel alloy powder is as follows (by mass fraction): C: 0.01-0.08%, B: 0.5-1.5%, Si: 0.5-0.7%, Mn: 1.0-1.5%, P: 0.0025-0.035%, S: 0.020-0.025%, Ni: 12.0-15.0%, Cr: 18.0-20.0%, N: 0.05-0.07%, O: 0.003-0.004%, with the balance being Fe and unavoidable impurities.

4. The method for preparing an antibacterial stainless steel plate for refrigerator lining according to claim 1, characterized in that: In step two, the preparation process of mesoporous polydopamine nanoparticles is as follows: Pluronic F-127 and 1,3,5-trimethylbenzene are added sequentially to an ethanol aqueous solution, and after ultrasonic dispersion to obtain an emulsion, the mixture is magnetically stirred for 30-40 min. Then, Tris-HCl aqueous solution and dopamine hydrochloride are added sequentially, and the pH is adjusted to 8.5-8.

7. The mixture is reacted at 25-30℃ in the dark for 25-30 h. After the reaction is completed, the solid nanoparticles are collected at 3-5℃, and then ultrasonically cleaned, centrifuged, washed with deionized water, and freeze-dried to obtain mesoporous polydopamine nanoparticles.

5. The method for preparing an antibacterial stainless steel plate for refrigerator lining according to claim 4, characterized in that: The mass ratio of Pluronic F-127, 1,3,5-trimethylbenzene, Tris-HCl, and dopamine hydrochloride is (37-40):36:9:

6.

6. The method for preparing an antibacterial stainless steel plate for refrigerator lining according to claim 1, characterized in that: In step three, when preparing vinyl-terminated polyurethane, the reaction mass ratio of polypropylene glycol, polycaprolactone diol, isophorone diisocyanate, and hydroxyethyl methacrylate is 3:(1.0-1.6):2:

1.

7. The method for preparing an antibacterial stainless steel plate for refrigerator lining according to claim 1, characterized in that: In step three, the content of each component in the polyurethane-acrylic antibacterial coating is as follows (by mass fraction): 60-70% vinyl-terminated polyurethane, 15-20% acrylic-modified chitosan, 10-15% acrylated quaternary ammonium salt, 6-10% acrylic-modified tannic acid, with the balance being the photoinitiator 2-hydroxy-2-methyl-1-phenyl-1-propanone; the coating thickness is 20-30 μm.