A processing technology for antibacterial high-strength refrigerator lower beam

Abstract

The present invention relates to the technical field of coating materials, and specifically to a processing technology for an antibacterial high-strength refrigerator lower beam. The surface of the refrigerator lower beam has two coatings, including a metal layer coated on the surface of the refrigerator lower beam, and an antibacterial layer coated on the surface of the metal layer. The present invention prepares a graphene / titanium dioxide composite, performs a crystallization treatment on it, and then mixes it evenly with titanium carbonitride, cerium oxide, and sodium silicate. It adopts cold air power spraying technology to spray it onto the cleaned surface of the refrigerator lower beam to obtain a metal layer; the graphene / titanium dioxide composite that has not been crystallized is grafted and modified with chitosan and betaine to prepare a modified filler, and then it is mixed evenly with polyurethane grafted acrylic emulsion, sodium hydroxymethyl cellulose, sodium hexametaphosphate, an antibacterial agent, a film-forming aid, and deionized water to obtain an antibacterial coating; the antibacterial coating is evenly coated on the surface of the metal layer, and after curing, an antibacterial layer is obtained, and finally an antibacterial high-strength refrigerator lower beam is prepared.

Description

Technical Field

[0001] The invention relates to the technical field of coating materials, and in particular to a processing technology for an antibacterial high-strength refrigerator lower beam. Background Art

[0002] As people's lives improve, refrigerators have become a must-have household item. As a constant low-temperature refrigeration device, they are primarily used to store a variety of foods, including vegetables and meat. Inevitably, during power outages or when food is stored for long periods, the food inside the refrigerator will spoil, leaking into the refrigerator's lower beam. The humid environment breeds bacteria, accelerating corrosion of the lower beam. Furthermore, the refrigerator's lower beam must support the weight of the entire refrigerator and the food. Furthermore, to meet modern living needs, refrigerators are becoming larger and larger, requiring them to bear greater loads than traditional refrigerators.

[0003] To sum up, in order to ensure the quality of the refrigerator, the present invention will prepare two coatings, which will be evenly applied to the lower beam of the refrigerator one after another, so that it has good antibacterial ability and can also enhance its mechanical properties. Finally, an antibacterial and high-strength refrigerator lower beam is comprehensively prepared. Summary of the Invention

[0004] The object of the present invention is to provide a processing technology for an antibacterial high-strength refrigerator lower beam to solve the problems raised in the above background technology.

[0005] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0006] The invention discloses an antibacterial high-strength refrigerator lower beam, the surface of which has two coatings, including a metal layer coated on the surface of the refrigerator lower beam and an antibacterial layer coated on the surface of the metal layer.

[0007] More optimally, the processing technology of the antibacterial high-strength refrigerator lower beam includes the following steps:

[0008] Step 1: preparing a graphene / titanium dioxide composite, and subjecting it to crystallization treatment to obtain a graphene / titanium dioxide composite material;

[0009] Step 2: (1) performing carboxylation pretreatment on the graphene / titanium dioxide composite to obtain a pretreated graphene / titanium dioxide composite;

[0010] (2) Modifying and grafting chitosan with carboxylic acid betaine methyl methacrylate to obtain modified chitosan;

[0011] (3) reacting the modified chitosan with the pretreated graphene / titanium dioxide composite to obtain a modified filler;

[0012] Step 3: (1) mixing the graphene / titanium dioxide composite material with titanium carbonitride, cerium oxide, and sodium silicate uniformly, and spraying the mixture onto the cleaned surface of the refrigerator lower beam using a cold air power spraying technique to obtain a metal layer;

[0013] (2) The metal layer is first irradiated with an electron beam; then the modified filler is evenly mixed with polyurethane grafted acrylic emulsion, sodium hydroxymethyl cellulose, sodium hexametaphosphate, an antibacterial agent, a film-forming aid, and deionized water to obtain an antibacterial coating; the antibacterial coating is evenly applied to the surface of the metal layer, and the antibacterial layer is obtained by baking and curing, and finally an antibacterial high-strength refrigerator lower beam is prepared.

[0014] More optimally, the preparation method of the graphene / titanium dioxide composite material is:

[0015] (1) dissolving tetraisobutyl titanate in anhydrous ethanol to prepare solution A; dissolving graphene oxide in deionized water to prepare solution B;

[0016] (2) adding solution B to solution A, mechanically stirring for 15 to 30 minutes, and then standing for 1 to 3 hours to allow titanium ions to adsorb onto the surface of graphene oxide and undergo sufficient hydrolysis, and then obtaining a graphene / titanium dioxide composite through deposition, filtration, and drying;

[0017] (3) Add half the volume of ammonia water into a sealed high-pressure hydrothermal reactor, place the graphene / titanium dioxide composite on top of the ammonia water, set the pressure to 80-120 MPa, the temperature to 150-300°C, and react at a constant temperature for 24-72 hours to obtain a graphene / titanium dioxide composite material.

[0018] More optimally, the mass ratio of tetraisobutyl titanate to graphene oxide is 10:(1-2).

[0019] More optimally, the volume ratio of solution A to solution B is 2:1.

[0020] More optimally, the preparation method of the modified filler is:

[0021] (1) adding a graphene / titanium dioxide composite and an oxalic acid solution into a ball mill, and ball milling for 10 to 15 hours under a nitrogen atmosphere to carboxylate the graphene in the composite, and filtering, washing, and drying to obtain a pretreated graphene / titanium dioxide composite;

[0022] (2) dissolving carboxylic acid betaine methyl methacrylate in dimethyl sulfoxide, adding chitosan thereto, ultrasonically dispersing for 15 to 30 minutes, then adding concentrated sulfuric acid, heating to 140 to 160° C., reacting for 2 to 4 hours, filtering, washing, and drying to obtain modified chitosan;

[0023] (3) The modified chitosan was dissolved in acetic acid, and the pretreated graphene / titanium dioxide composite was added. After ultrasonic dispersion for 15 to 30 minutes, dicyclohexylcarbodiimide was added and stirred at 0 to 10°C for 1 to 3 hours. The mixture was then allowed to stand at room temperature for 3 to 6 hours. The modified filler was obtained by filtration, washing, and drying.

[0024] More optimally, the mass ratio of the graphene / titanium dioxide composite to oxalic acid is 1:20.

[0025] More optimally, the mass ratio of the carboxylic acid betaine methyl methacrylate, dimethyl sulfoxide, chitosan and concentrated sulfuric acid is (8-10):100:20:0.05.

[0026] More optimally, the mass ratio of the modified chitosan, acetic acid, pretreated graphene / titanium dioxide composite, and dicyclohexylcarbodiimide is 2:10:1:5.

[0027] More optimally, the metal layer includes the following component raw materials, calculated by weight: 20-40 parts of graphene / titanium dioxide composite material, 6-12 parts of titanium carbonitride, 5-10 parts of cerium oxide, and 1-2.5 parts of sodium silicate.

[0028] More optimally, the average particle size of the raw materials of each component of the metal layer is 10 to 30 μm.

[0029] More preferably, the titanium carbonitride is titanium carbonitride whiskers.

[0030] More optimally, the cold air power spraying technology has the following characteristics: spraying temperature: 100-650°C, spraying pressure: 1-4 MPa, working gas: nitrogen, spraying distance: 10-50 mm, spraying thickness: 200-500 μm.

[0031] More optimally, the cleaning comprises ultrasonically cleaning the lower beam of the refrigerator with anhydrous ethanol and acetone in sequence for 15 to 30 minutes.

[0032] More optimally, the electron beam irradiation dose is 70 to 150 KGy, and the irradiation time is 30 to 120 minutes.

[0033] More optimally, the antibacterial coating includes the following component raw materials, calculated by weight: 60-80 parts of polyurethane grafted acrylic emulsion, 8-15 parts of modified filler, 8-15 parts of sodium hydroxymethyl cellulose, 2-4 parts of antibacterial agent, 3-8 parts of film-forming aid, 2-5 parts of sodium hexametaphosphate, and 15-30 parts of deionized water.

[0034] More optimally, the polyurethane grafted acrylic emulsion model is JZ-416, provided by Nanjing Jiazhong Chemical Technology Co., Ltd.

[0035] More optimally, the film-forming aid is at least one of propylene glycol butyl ether, propylene glycol methyl ether acetate or alcohol ester dodecahydrate.

[0036] More optimally, the antibacterial coating has a coating thickness of 40 to 100 μm.

[0037] More optimally, the baking parameters are: baking temperature: 70-90° C., baking time: 6-24 hours.

[0038] Compared with the prior art, the beneficial effects achieved by the present invention are as follows: the present invention coats a metal layer and an antibacterial layer on the lower beam of the refrigerator in sequence, ultimately making the lower beam of the refrigerator have antibacterial and high-strength properties; the antibacterial and high-strength lower beam of the refrigerator prepared by the present invention has good bonding strength between the layers, wherein the metal layer provides high strength, the antibacterial layer provides antibacterial properties, and the antibacterial layer can also provide excellent corrosion resistance, so that the product prepared by the present invention has a longer service life and has certain economic and practical value.

[0039] (1) In the scheme, step 1 prepares a graphene / titanium dioxide composite material. Since crystalline materials have better mechanical properties than amorphous materials, the graphene / titanium dioxide composite is transformed from an amorphous state to a crystalline state by using ammonia and water in a closed high-pressure hydrothermal reactor, so that the prepared composite material has higher mechanical strength and hardness, and the metal layer has better mechanical properties. On the other hand, compared with the traditional use of toxic reagents such as hydrazine hydrate, this scheme is safer and more environmentally friendly, and the reaction system can be reused.

[0040] (2) In the scheme, since betaine and chitosan have good antibacterial effects, in step 2, betaine methyl methacrylate is used to react with chitosan to undergo an esterification reaction, so that the two are grafted together to prepare a modified chitosan with excellent antibacterial properties; graphene and titanium dioxide also have excellent antibacterial effects, and the two are composited as fillers to enhance the antibacterial effect of the filler; on the other hand, since the amorphous graphene / titanium dioxide composite material has better corrosion resistance as a filler than the crystalline graphene / titanium dioxide composite material, in step 2, the modified chitosan is grafted with the amorphous graphene / titanium dioxide composite prepared in step 1, and finally a modified filler is obtained; the antibacterial layer has excellent antibacterial properties and a certain corrosion resistance, so that the protective coating has a longer effective life;

[0041] (3) In the scheme, titanium carbonitride whiskers are further added to the metal layer, which can greatly improve the strength of the coating and act on the lower beam of the refrigerator. They work together with the graphene / titanium dioxide composite material to enhance the strength of the lower beam of the refrigerator; the metal layer is sprayed with cold air power spraying technology, which is easy to operate, not only has good bonding strength between the metal layer and the substrate, but also has a uniform surface of the metal layer;

[0042] In the (4) scheme, the metal layer is further subjected to electron irradiation treatment to produce defects in the graphene in the metal layer, so that the antibacterial coating can be more tightly bonded to the metal layer; since betaine has a certain hydrophilicity, it will also affect the life of the antibacterial layer to a certain extent, so polyurethane grafted acrylic emulsion is further added to the antibacterial coating to further provide an antibacterial effect while improving the water resistance and corrosion resistance of the antibacterial layer, so that the prepared antibacterial high-strength refrigerator lower beam has more excellent practicality. DETAILED DESCRIPTION

[0043] 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.

[0044] It should be noted that the purchasers of all raw materials involved in the present invention include, without any special restrictions, the following examples:

[0045] Graphene oxide purity is 99.50%, single layer, sheet diameter: 0.5-5μm, thickness: 0.8-1.2nm (Yunguan (Shanghai) Biotechnology Co., Ltd.), tetraisobutyl titanate purity is 99% (Shanghai Jinjinle Industrial Co., Ltd.), oxalic acid purity is 99% (Hubei Yongkuo Technology Co., Ltd.), carboxylic acid betaine methyl methacrylate purity is 98%, CAS number: 24249-95-4, item number: Y32042 (Shanghai Yuanye Biotechnology Co., Ltd.), chitosan oligosaccharide purity is 99% (Hubei Yongkuo Technology Co., Ltd.), dicyclohexylcarbodiimide purity is 99% (Hubei Xinkang Pharmaceutical Chemical Co., Ltd.), carbonitridation The purity of titanium whiskers is 98% (Hubei Zhenbo Chemical Co., Ltd.), the purity of cerium oxide is 99.9% (Shanghai Yuanye Biotechnology Co., Ltd.), the purity of sodium silicate is 99% (Zhenjiang Mingde Chemical Trading Co., Ltd.), the polyurethane grafted acrylic emulsion model is JZ-416 (Nanjing Jiazhong Chemical Technology Co., Ltd.), the purity of sodium hydroxymethyl cellulose is 99% (Shandong Yonglida New Materials Technology Co., Ltd.), the antibacterial agent model is YG100 (Dongguan Nabaichuan Plastic Co., Ltd.), the purity of propylene glycol butyl ether is 99.5% (Shandong Yonglida New Materials Technology Co., Ltd.), and the purity of sodium hexametaphosphate is 95% (Shanghai Yuanye Biotechnology Co., Ltd.).

[0046] Example 1: A processing technology for antibacterial high-strength refrigerator lower beam:

[0047] Step 1: (1) dissolving 100 parts of tetraisobutyl titanate in anhydrous ethanol to prepare 2 L of solution A; dissolving 16 parts of graphene oxide in deionized water to prepare 1 L of solution B;

[0048] (2) adding all of solution B to solution A, mechanically stirring for 30 min, and then standing for 3 h to allow titanium ions to adsorb onto the surface of graphene oxide and undergo sufficient hydrolysis. After sedimentation, filtration, and drying, a graphene / titanium dioxide composite was obtained;

[0049] (3) adding half the volume of 20 wt% ammonia water into a sealed high-pressure hydrothermal reactor, placing the graphene / titanium dioxide composite on top of the ammonia water, setting the pressure to 100 MPa and the temperature to 180° C., and reacting at this constant temperature for 48 h to obtain a graphene / titanium dioxide composite material;

[0050] Step 2: (1) adding 20 parts of graphene / titanium dioxide composite and 400 parts of oxalic acid solution into a ball mill, and ball milling for 12 hours under a nitrogen atmosphere to carboxylate the graphene in the composite, and filtering, washing, and drying to obtain a pretreated graphene / titanium dioxide composite;

[0051] (2) 9 parts of carboxylic acid betaine methyl methacrylate were dissolved in 100 parts of dimethyl sulfoxide, 20 parts of chitosan were added thereto, and after ultrasonic dispersion for 30 minutes, 0.05 parts of concentrated sulfuric acid were added, and the temperature was raised to 150°C, and the reaction was carried out for 3 hours. The modified chitosan was obtained after filtering, washing, and drying;

[0052] (3) 16 parts of modified chitosan were dissolved in 80 parts of acetic acid, 8 parts of pretreated graphene / titanium dioxide composite were added, and after ultrasonic dispersion for 30 minutes, 40 parts of dicyclohexylcarbodiimide were added, and the mixture was stirred at 0°C for 3 hours, and then allowed to stand at room temperature for 5 hours. The modified filler was obtained by filtration, washing, and drying.

[0053] Step 3: 35 parts of graphene / titanium dioxide composite material were mixed evenly with 10 parts of titanium carbonitride whiskers, 7 parts of cerium oxide, and 1.5 parts of sodium silicate; an ultrasonic cleaning of the refrigerator lower beam made of S25073 stainless steel was carried out with anhydrous ethanol and acetone for 30 minutes in sequence; then, a cold air power spraying technology was used, with the spraying temperature set at 350°C and the spraying pressure set at 3.2 MPa, and nitrogen as the working gas, to spray a metal layer at a distance of 30 mm from the surface of the lower beam with a spraying thickness of 300 μm to obtain a metal layer;

[0054] Step 4: After the metal layer cools to room temperature, the surface of the metal layer is irradiated with an electron beam at a dose of 80 KGy for 60 minutes.

[0055] Step 5: Mix 12 parts of modified filler with 72 parts of polyurethane grafted acrylic emulsion, 10 parts of sodium hydroxymethyl cellulose, 3 parts of antibacterial agent, 6 parts of propylene glycol butyl ether, 4 parts of sodium hexametaphosphate, and 20 parts of deionized water to obtain an antibacterial coating; evenly apply the antibacterial coating to the surface of the metal layer with a coating thickness of 60 μm; then place it in an oven and bake it at 80°C for 24 hours to obtain an antibacterial layer, and finally prepare an antibacterial high-strength refrigerator lower beam.

[0056] Example 2: A processing technology for antibacterial high-strength refrigerator lower beam:

[0057] Step 1: (1) dissolving 100 parts of tetraisobutyl titanate in anhydrous ethanol to prepare 2 L of solution A; dissolving 10 parts of graphene oxide in deionized water to prepare 1 L of solution B;

[0058] (2) adding all of solution B to solution A, mechanically stirring for 15 min, and then standing for 1 h to allow titanium ions to adsorb onto the surface of graphene oxide and undergo sufficient hydrolysis. After sedimentation, filtration, and drying, a graphene / titanium dioxide composite was obtained;

[0059] (3) adding half the volume of 20 wt% ammonia water into a sealed high-pressure hydrothermal reactor, placing the graphene / titanium dioxide composite on top of the ammonia water, setting the pressure to 80 MPa and the temperature to 150 ° C, and reacting at this temperature for 24 h to obtain a graphene / titanium dioxide composite material;

[0060] Step 2: (1) adding 20 parts of graphene / titanium dioxide composite and 400 parts of oxalic acid solution into a ball mill, and ball milling for 12 hours under a nitrogen atmosphere to carboxylate the graphene in the composite, and filtering, washing, and drying to obtain a pretreated graphene / titanium dioxide composite;

[0061] (2) 8 parts of carboxylic acid betaine methyl methacrylate were dissolved in 100 parts of dimethyl sulfoxide, 20 parts of chitosan were added thereto, and after ultrasonic dispersion for 30 minutes, 0.05 parts of concentrated sulfuric acid were added, and the temperature was raised to 150°C, and the reaction was carried out for 3 hours. The modified chitosan was obtained after filtering, washing, and drying;

[0062] (3) 16 parts of modified chitosan were dissolved in 80 parts of acetic acid, 8 parts of pretreated graphene / titanium dioxide composite were added, and after ultrasonic dispersion for 30 minutes, 40 parts of dicyclohexylcarbodiimide were added, and the mixture was stirred at 0°C for 3 hours, and then allowed to stand at room temperature for 5 hours. The modified filler was obtained by filtration, washing, and drying.

[0063] Step 3: 35 parts of graphene / titanium dioxide composite material were mixed evenly with 10 parts of titanium carbonitride whiskers, 7 parts of cerium oxide, and 1.5 parts of sodium silicate; an ultrasonic cleaning of the refrigerator lower beam made of S25073 stainless steel was carried out with anhydrous ethanol and acetone for 30 minutes in sequence; then, a cold air power spraying technology was used, with the spraying temperature set at 350°C and the spraying pressure set at 3.2 MPa, and nitrogen as the working gas, to spray a metal layer at a distance of 30 mm from the surface of the lower beam with a spraying thickness of 300 μm to obtain a metal layer;

[0064] Step 4: After the metal layer cools to room temperature, the surface of the metal layer is irradiated with an electron beam at a dose of 80 KGy for 60 minutes.

[0065] Step 5: Mix 12 parts of modified filler with 72 parts of polyurethane grafted acrylic emulsion, 10 parts of sodium hydroxymethyl cellulose, 3 parts of antibacterial agent, 6 parts of propylene glycol butyl ether, 4 parts of sodium hexametaphosphate, and 20 parts of deionized water to obtain an antibacterial coating; evenly apply the antibacterial coating to the surface of the metal layer with a coating thickness of 60 μm; then place it in an oven and bake it at 80°C for 24 hours to obtain an antibacterial layer, and finally prepare an antibacterial high-strength refrigerator lower beam.

[0066] Example 3: A processing technology for antibacterial high-strength refrigerator lower beam:

[0067] Step 1: (1) dissolving 100 parts of tetraisobutyl titanate in anhydrous ethanol to prepare 2 L of solution A; dissolving 10 parts of graphene oxide in deionized water to prepare 1 L of solution B;

[0068] (2) adding all of solution B to solution A, mechanically stirring for 30 min, and then standing for 3 h to allow titanium ions to adsorb onto the surface of graphene oxide and undergo sufficient hydrolysis. After sedimentation, filtration, and drying, a graphene / titanium dioxide composite was obtained;

[0069] (3) adding half the volume of 20 wt% ammonia water into a sealed high-pressure hydrothermal reactor, placing the graphene / titanium dioxide composite on top of the ammonia water, setting the pressure to 120 MPa and the temperature to 180 ° C, and conducting a constant temperature reaction for 72 h to obtain a graphene / titanium dioxide composite material;

[0070] Step 2: (1) adding 20 parts of graphene / titanium dioxide composite and 400 parts of oxalic acid solution into a ball mill, and ball milling for 12 hours under a nitrogen atmosphere to carboxylate the graphene in the composite, and filtering, washing, and drying to obtain a pretreated graphene / titanium dioxide composite;

[0071] (2) 10 parts of carboxylic acid betaine methyl methacrylate were dissolved in 100 parts of dimethyl sulfoxide, 20 parts of chitosan were added thereto, and after ultrasonic dispersion for 30 minutes, 0.05 parts of concentrated sulfuric acid were added, and the temperature was raised to 150°C, and the reaction was carried out for 3 hours. The modified chitosan was obtained by filtering, washing, and drying;

[0072] (3) 16 parts of modified chitosan were dissolved in 80 parts of acetic acid, 8 parts of pretreated graphene / titanium dioxide composite were added, and after ultrasonic dispersion for 30 minutes, 40 parts of dicyclohexylcarbodiimide were added, and the mixture was stirred at 0°C for 3 hours, and then allowed to stand at room temperature for 5 hours. The modified filler was obtained by filtration, washing, and drying.

[0073] Step 3: 35 parts of graphene / titanium dioxide composite material were mixed evenly with 10 parts of titanium carbonitride whiskers, 7 parts of cerium oxide, and 1.5 parts of sodium silicate; an ultrasonic cleaning of the refrigerator lower beam made of S25073 stainless steel was carried out with anhydrous ethanol and acetone for 30 minutes in sequence; then, a cold air power spraying technology was used, with the spraying temperature set at 350°C and the spraying pressure set at 3.2 MPa, and nitrogen as the working gas, to spray a metal layer at a distance of 30 mm from the surface of the lower beam with a spraying thickness of 300 μm to obtain a metal layer;

[0074] Step 4: After the metal layer cools to room temperature, the surface of the metal layer is irradiated with an electron beam at a dose of 80 KGy for 60 minutes.

[0075] Step 5: Mix 12 parts of modified filler with 72 parts of polyurethane grafted acrylic emulsion, 10 parts of sodium hydroxymethyl cellulose, 3 parts of antibacterial agent, 6 parts of propylene glycol butyl ether, 4 parts of sodium hexametaphosphate, and 20 parts of deionized water to obtain an antibacterial coating; evenly apply the antibacterial coating to the surface of the metal layer with a coating thickness of 60 μm; then place it in an oven and bake it at 80°C for 24 hours to obtain an antibacterial layer, and finally prepare an antibacterial high-strength refrigerator lower beam.

[0076] Comparative Example 1: The graphene / titanium dioxide composite was not crystallized, and the other aspects were the same as in Example 1; specifically, step 3: 35 parts of the graphene / titanium dioxide composite were uniformly mixed with 10 parts of titanium carbonitride whiskers, 7 parts of cerium oxide, and 1.5 parts of sodium silicate. A cold air power spraying technique was used, with the spraying temperature set at 350° C. and the spraying pressure set at 3.2 MPa. Nitrogen was used as the working gas, and a metal layer was sprayed at a distance of 30 mm from the surface of the lower beam to a thickness of 300 μm to obtain a metal layer.

[0077] Comparative Example 2: Modified chitosan was not prepared, and the graphene / titanium dioxide composite was modified with γ-methacryloxypropyltrimethoxysilane; other conditions were the same as in Example 1;

[0078] Step 2: Add 20 parts of graphene / titanium dioxide composite to 100 parts of anhydrous ethanol solution, add γ-methacryloxypropyltrimethoxysilane and ethyl orthosilicate, stir and disperse evenly, then adjust the pH to 5 with hydrochloric acid, react at 50°C for 24 hours to obtain a modified filler;

[0079] Comparative Example 3: Titanium carbonitride powder was used for titanium carbonitride; other aspects were the same as in Example 1;

[0080] Comparative Example 4: Plasma spraying technology was used to spray metal powder onto the surface of the lower beam of the refrigerator; other aspects were the same as in Example 1; specifically:

[0081] Step 3: 35 parts of graphene / titanium dioxide composite material are mixed evenly with 10 parts of titanium carbonitride whiskers, 7 parts of cerium oxide, and 1.5 parts of sodium silicate; the lower beam of the refrigerator made of S25073 stainless steel is ultrasonically cleaned with anhydrous ethanol and acetone for 30 minutes in sequence; then plasma spraying technology is used, with nitrogen as the main working gas, the flow rate is 4sl / m; the secondary gas is hydrogen, the flow rate is 60sl / m; the metal powder gas flow rate is 5sl / m, the powder feeding rate is 45g / min; the spraying current is 400A, the voltage is 50V; the spraying distance is 30mm, and the spraying thickness is 300μm to obtain a metal layer;

[0082] Comparative Example 5: The metal layer is not subjected to electron beam irradiation, and the rest is the same as in Example 1.

[0083] Performance test: Antibacterial performance test and strength test were performed on the antibacterial high-strength refrigerator lower beams prepared in Examples 1 to 3 and Comparative Examples 1 to 5 and the original refrigerator lower beams made of S25073 stainless steel without coating treatment;

[0084] Antibacterial performance test: (1) Staphylococcus aureus and Candida albicans were inoculated onto nutrient agar medium, cultured at 37°C for 36 h, and then typical colonies were picked from the agar medium and inoculated into two fresh nutrient broth media, cultured at 37°C for 36 h to obtain bacterial suspension;

[0085] (2) Select two 2 cm × 2 cm areas on the surface of the lower beam of each refrigerator, isolate them from other parts, apply the two bacterial solutions to different areas, and after 1 hour, check the residual area of each colony in the area;

[0086] Strength test: According to the experimental method in GB / T 228.2-2015, the yield strength is measured using a universal material testing machine; the specific values are shown in Table 1:

[0087] Table 1

[0088]

[0089] Result analysis: According to the data in the above table, it can be seen that the antibacterial and high-strength refrigerator lower beam prepared by the present invention has an obvious antibacterial effect compared with the original refrigerator lower beam, indicating that the present invention uses chitosan and betaine to synergistically modify the graphene / titanium dioxide composite to obtain a modified filler, which has a positive antibacterial effect; and the crystallization of the graphene / titanium dioxide composite in the scheme also has a great influence on the strength of the lower beam; finally, the present invention prepares a refrigerator lower beam with high antibacterial effect and high strength, which is of great significance.

[0090] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art will be able to modify the technical solutions described in the aforementioned embodiments or substitute equivalents for some of the technical features. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. An antibacterial high-strength refrigerator lower beam, characterized by: There are two coatings on its surface, including a metal layer coated on the surface of the lower beam of the refrigerator, and an antibacterial layer coated on the surface of the metal layer; The metal layer comprises the following raw materials, calculated by weight: 20 to 40 parts of graphene / titanium dioxide composite material, 6 to 12 parts of titanium carbonitride, 5 to 10 parts of cerium oxide, and 1 to 2.5 parts of sodium silicate; The antibacterial layer is obtained by coating and curing the antibacterial coating; The antibacterial coating comprises the following raw materials, calculated by weight: 60-80 parts of polyurethane grafted acrylic emulsion, 8-15 parts of modified filler, 8-15 parts of sodium hydroxymethyl cellulose, 2-4 parts of antibacterial agent, 3-8 parts of film-forming aid, 2-5 parts of sodium hexametaphosphate, and 15-30 parts of deionized water; The preparation method of the graphene / titanium dioxide composite material is: (1) dissolving tetraisobutyl titanate in anhydrous ethanol to prepare solution A; dissolving graphene oxide in deionized water to prepare solution B; (2) adding solution B to solution A, mechanically stirring for 15 to 30 minutes, and then standing for 1 to 3 hours, followed by sedimentation, filtration, and drying to obtain a graphene / titanium dioxide composite; (3) adding ammonia water to the reactor, placing the graphene / titanium dioxide composite on top of the ammonia water, setting the pressure to 80-120 MPa and the temperature to 150-300° C., and reacting at a constant temperature for 24-72 hours to obtain a graphene / titanium dioxide composite material; The mass ratio of tetraisobutyl titanate and graphene oxide is 10:(1-2); the volume ratio of solution A and solution B is 2:1; The preparation method of the modified filler is: (1) adding a graphene / titanium dioxide composite and oxalic acid into a ball mill, ball milling for 10 to 15 hours under a nitrogen atmosphere, filtering, washing, and drying to obtain a pretreated graphene / titanium dioxide composite; (2) dissolving carboxylic acid betaine methyl methacrylate in dimethyl sulfoxide, adding chitosan thereto, ultrasonically dispersing for 15 to 30 minutes, then adding concentrated sulfuric acid, heating to 140 to 160° C., reacting for 2 to 4 hours, filtering, washing, and drying to obtain modified chitosan; (3) dissolving the modified chitosan in acetic acid, adding the pretreated graphene / titanium dioxide composite, ultrasonically dispersing for 15 to 30 minutes, adding dicyclohexylcarbodiimide, stirring and reacting at 0 to 10°C for 1 to 3 hours, and then standing at room temperature for 3 to 6 hours, filtering, washing, and drying to obtain a modified filler; Among them, the mass ratio of graphene / titanium dioxide composite and oxalic acid is 1:20; the mass ratio of carboxylic acid betaine methyl methacrylate, dimethyl sulfoxide, chitosan and concentrated sulfuric acid is (8-10):100:20:0.05; the mass ratio of modified chitosan, acetic acid, pretreated graphene / titanium dioxide composite and dicyclohexylcarbodiimide is 2:10:1:

5.

2. The process for processing a bacteriostatic high-strength refrigerator lower beam according to claim 1, characterized in that: The following steps are involved: Step 1: preparing a graphene / titanium dioxide composite; and then performing a crystallization treatment to obtain a graphene / titanium dioxide composite material; Step 2: (1) performing carboxylation pretreatment on the graphene / titanium dioxide composite to obtain a pretreated graphene / titanium dioxide composite; (2) Modifying and grafting chitosan with carboxylic acid betaine methyl methacrylate to obtain modified chitosan; (3) reacting the modified chitosan with the pretreated graphene / titanium dioxide composite to obtain a modified filler; Step 3: (1) mixing the graphene / titanium dioxide composite material with titanium carbonitride, cerium oxide, and sodium silicate uniformly, and spraying the mixture onto the cleaned surface of the refrigerator lower beam using a cold air power spraying technique to obtain a metal layer; (2) The metal layer is first irradiated with an electron beam; then the modified filler is evenly mixed with polyurethane grafted acrylic emulsion, sodium hydroxymethyl cellulose, sodium hexametaphosphate, an antibacterial agent, a film-forming aid, and deionized water to obtain an antibacterial coating; the antibacterial coating is evenly applied to the surface of the metal layer, and the antibacterial layer is obtained by baking and curing, and finally an antibacterial high-strength refrigerator lower beam is prepared.

3. The process for processing a bacteriostatic high-strength refrigerator lower beam according to claim 1, characterized in that: The titanium carbonitride is titanium carbonitride whiskers.

4. The process for processing a bacteriostatic high-strength refrigerator lower beam according to claim 2, characterized in that: The cold air power spraying technology has the following characteristics: spraying temperature: 100-650°C, spraying pressure: 1-4 MPa, working gas: nitrogen, spraying distance: 10-50 mm, spraying thickness: 200-500 μm.

5. The process for processing a bacteriostatic high-strength refrigerator lower beam according to claim 2, characterized in that: The electron beam irradiation dose is 70 to 150 KGy, and the irradiation time is 30 to 120 minutes.

6. The process for processing a bacteriostatic high-strength refrigerator lower beam according to claim 2, characterized in that: The coating thickness of the antibacterial coating is 40 to 100 μm; the baking parameters are as follows: baking temperature is 70 to 90° C., and baking time is 6 to 24 hours.

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