A food-grade stainless steel straw with an antibacterial coating and a method of making the same

Abstract

The application relates to the technical field of stainless steel straws, and discloses a food-grade stainless steel straw with an antibacterial coating and a preparation method thereof; the method comprises the following operation steps: step 1: cutting a food-grade stainless steel pipe into a required length, carrying out degreasing and pickling in sequence to obtain a food-grade stainless steel straw base body; the food-grade stainless steel straw base body is placed in an electroplating solution to carry out electroplating, and a pre-plated food-grade stainless steel straw is obtained; step 2: the pre-plated food-grade stainless steel straw is first immersed in a composite nano-silver sol for 40-60s, taken out and dried to form an antibacterial layer; the food-grade stainless steel straw is transferred to modified polysiloxane slurry to be immersed for 30-50s, taken out and dried to form a hydrophobic layer; and the food-grade stainless steel straw is obtained.

Description

Technical Field

[0001] The invention relates to the technical field of stainless steel straws, in particular to a food-grade stainless steel straw with an antibacterial coating and a preparation method thereof. Background Art

[0002] Food-grade stainless steel straws, as an environmentally friendly alternative to disposable plastic straws, pose health risks because they are prone to residual food residues and the breeding of microorganisms (such as Escherichia coli and Staphylococcus aureus) inside; traditional antibacterial methods (such as adding silver / copper ions) have limited effects, while superhydrophobic coatings can enhance antibacterial properties through a dual mechanism: inhibiting bacterial adhesion: the hydrophobic surface reduces bacterial adhesion mediated by water molecules and destroys their stable attachment; blocking nutrient supply: the hydrophobic layer weakens the surface's adsorption of nutrients, limiting bacterial growth and reproduction.

[0003] This solution combines a super-hydrophobic coating and an antibacterial layer on the surface of food-grade stainless steel straws, enhancing long-term antibacterial properties through synergistic effects; the hydrophobic layer reduces initial bacterial attachment, and the antibacterial agent further kills residual microorganisms. This design not only solves the cleaning problem, but also makes up for the shortcomings of a single antibacterial technology, significantly improving safety of use.

[0004] In summary, it is of great significance to prepare a food-grade stainless steel straw with an antibacterial coating. Summary of the Invention

[0005] The object of the present invention is to provide a food-grade stainless steel straw with an antibacterial coating and a preparation method thereof, so as to solve the problems raised in the prior art.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] A method for preparing a food-grade stainless steel straw with an antibacterial coating comprises the following steps:

[0008] Step 1: Cut the food-grade stainless steel pipe into the required length, degrease and pickle it in sequence to obtain a food-grade stainless steel straw substrate; place the food-grade stainless steel straw substrate in an electroplating solution for electroplating to obtain a pre-plated food-grade stainless steel straw;

[0009] Step 2: The pre-plated food-grade stainless steel straw is first immersed in the composite nanosilver sol for 40 to 60 seconds, taken out and dried to form an antibacterial layer; then transferred to the modified polysiloxane slurry and immersed for 30 to 50 seconds, taken out and dried to form a hydrophobic layer; and a food-grade stainless steel straw is obtained.

[0010] More optimally, the raw materials of the electroplating solution include the following components: 20-25 g / L copper sulfate, 0.08-0.12 g / L modified polylysine, 2-3 g / L potassium chloride, and 0.03-0.05 mol / L hydrochloric acid, calculated by mass.

[0011] A more optimized preparation method of the modified polylysine is as follows: under nitrogen protection, EDC and NHS are added to MES buffer and uniformly mixed, Boc-arginine and caffeic acid are added in an ice-water bath and stirred for 30-40 minutes, polylysine is added and stirred for 5-6 hours, dialyzed for 1-2 days, freeze-dried, placed in a 25-30wt% trifluoroacetic acid in DCM system and stirred for 1-2 hours to remove the protecting group, the solvent is removed, washed and freeze-dried to obtain the modified polylysine.

[0012] More optimally, the raw materials of the modified polylysine include the following components: 1.5-2.5 parts of polylysine, 0.2-0.3 parts of caffeic acid, 0.4-0.7 parts of Boc-arginine, 0.5-0.55 parts of EDC, and 0.3-0.33 parts of NHS, by mass; the MES buffer concentration is 0.1-0.12M, and the pH is 5-5.5.

[0013] A more optimized preparation method of the composite nano-silver sol is as follows: adding modified polylysine to deionized water, heating to 70-90°C, adding silver nitrate aqueous solution and mixing evenly, adding sodium citrate solution and sodium hydroxide aqueous solution, stirring for 1-1.5 hours, cooling to room temperature and standing to obtain a composite nano-silver sol.

[0014] More optimally, the raw materials of the composite nanosilver sol include the following components: by mass, 0.3-0.5 parts of modified polylysine, 1-1.5 parts of silver nitrate aqueous solution, 0.12-0.15 parts of sodium citrate solution, and 1-3 parts of sodium hydroxide aqueous solution; the concentration of the silver nitrate aqueous solution is 0.1-0.2M; the concentration of the sodium citrate solution is 0.1-0.15M; and the concentration of the sodium hydroxide aqueous solution is 1-2wt%.

[0015] The preparation method of the modified polysiloxane is as follows: (1) adding octadecyltrimethoxysilane and 3-(2,3-epoxypropoxy)propyltrimethoxysilane to anhydrous ethanol, mixing them evenly, adjusting the pH to 5-6, stirring at 60-70°C for 4-5 hours, removing the solvent to obtain branched polysiloxane; (2) adding 4-imidazole acrylic acid to acetone, mixing them evenly, adding vinyl-terminated polydimethylsiloxane and AIBN, stirring them evenly, heating to 60-65°C, stirring for 1-2 hours, adding methacrylic acid condensate, and stirring them evenly. The hydroglycerol ester and AIBN were stirred for 2 to 3 hours, cooled to room temperature, added to a mixed solution of cold ether and n-hexane for precipitation, and repeated 3 to 4 times to obtain modified polydimethylsiloxane; (3) amino-type nano-zinc oxide was ultrasonically dispersed in DMF, modified polydimethylsiloxane was added, and stirred at 50 to 60 ° C for 2 to 3 hours, branched polysiloxane was added and stirred for 3 to 4 hours, the solvent was removed, washed and dried to obtain modified polysiloxane; the modified polysiloxane was added to acetone for ultrasonic dispersion to obtain modified polysiloxane slurry.

[0016] More optimally, the raw materials of the modified polydimethylsiloxane include the following components: 0.3-0.5 parts of 4-imidazole acrylic acid, 1-2 parts of vinyl-terminated polydimethylsiloxane, 0.2-0.3 parts of glycidyl methacrylate, and 0.01-0.02 parts of AIBN in parts by mass; the mass ratio of the modified polydimethylsiloxane, amino-modified nano-zinc oxide, and branched polysiloxane is 1:(0.2-0.3):(0.05-0.08); the content of the modified polysiloxane in the modified polysiloxane slurry is 8-12 wt%.

[0017] The most optimized electroplating process conditions are: temperature 40-45°C, 4-6A / dm 2 The constant current time is 35~50s.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] In this solution, a superhydrophobic layer and an antibacterial layer are formed on the surface of a food-grade stainless steel straw, resulting in a food-grade stainless steel straw with an antibacterial coating. The superhydrophobic layer reduces the chance of bacteria attaching and growing in the gaps between the stainless steel straws, synergizing with the antibacterial layer to achieve a sustained antibacterial effect.

[0020] In order to improve the bonding between the antibacterial layer and the stainless steel straw substrate, the food-grade stainless steel straw substrate is pre-plated with a thin copper layer. The thin copper layer can improve the polarity and roughness of the stainless steel surface, providing an anchor point for the subsequent adhesion of the nano-silver sol, thereby improving the firmness and uniformity of the antibacterial layer; modified polylysine is added to the electroplating solution, which can be adsorbed on the stainless steel surface, improving the charge distribution during the electrodeposition process, and further optimizing the plating quality; the surface properties of the copper plating are more conducive to the adhesion of silver particles in the composite nano-silver sol and modified polysiloxane slurry, thereby ensuring a firm bond between the antibacterial layer and the hydrophobic layer and the substrate, thereby improving the comprehensive performance of the food-grade stainless steel straw.

[0021] In the scheme, the nanosilver sol itself has good broad-spectrum bactericidal properties; modified polylysine is introduced into the nanosilver sol to obtain a composite nanosilver sol; the introduction of modified polylysine can improve the binding force between the polylysine and the electroplating layer; among them, Boc (tert-butyloxycarbonyl) protects the amino group of arginine to prevent it from participating in other side reactions too early in the reaction process; the carboxyl group on caffeic acid is activated by EDC / NHS; the amino group on the polylysine molecular chain is the main reaction site, which is modified by covalent binding with Boc-arginine and caffeic acid, and finally the protecting group (Boc-) is removed to obtain modified polylysine; among them, the phenolic hydroxyl group on caffeic acid can coordinate with silver ions to improve the interfacial compatibility with the nanosilver sol; and arginine contains guanidine groups and has cationic properties, which can enhance the antibacterial properties of the material; natural polylysine itself has certain antibacterial properties, thereby further improving the antibacterial properties of the nanosilver sol;

[0022] The super-hydrophobic layer is made from a modified polydimethylsiloxane slurry. First, under weak acid conditions, the trimethoxysilane on octadecyltrimethoxysilane and 3-(2,3-epoxypropyloxy)propyltrimethoxysilane is hydrolyzed to form silanols. The silanols then dehydrate and condense to form Si-O-Si bonds, which gradually polymerize to form a branched structure.

[0023] The octadecyl group provides a hydrophobic segment, while the epoxy group introduces a reactive site. The double bond of 4-imidazole acrylic acid is first copolymerized with vinyl-terminated polydimethylsiloxane to introduce polar imidazole groups, which can form a coordination effect with the metal ions on the stainless steel surface, enhancing the bonding between the hydrophobic layer and the stainless steel straw. The double bond of GMA participates in the polymerization and connects to the polysiloxane chain, increasing the crosslinking points of the molecular chain. The polar group is introduced without destroying the hydrophobicity, thus balancing the adhesion and hydrophobic properties of the coating. A cold ether / n-hexane mixed solvent is used to precipitate the product and remove unreacted monomers and oligomers.

[0024] Among them, nano zinc oxide itself has certain antibacterial properties, can fill the pores of the coating, and enhance the antibacterial ability of stainless steel; amino nano zinc oxide undergoes a ring-opening reaction with the epoxy groups in modified polydimethylsiloxane and branched polysiloxane, thereby improving the dispersibility and interfacial bonding strength, and avoiding the degradation of coating performance caused by nanoparticle agglomeration; at the same time, through the synergy of branched polysiloxane and polydimethylsiloxane, a superhydrophobic layer is formed on the surface of stainless steel, which reduces bacterial attachment while synergizing with nano zinc oxide to improve antibacterial properties.

[0025] In the scheme, the modified polylysine contains amino groups, which can further improve the interfacial bonding force between the superhydrophobic layer and the antibacterial layer under certain conditions with the epoxy groups on the superhydrophobic layer; thereby reducing the attachment of bacteria while synergizing with the antibacterial layer to achieve the continuous antibacterial effect of food-grade stainless steel straws. DETAILED DESCRIPTION

[0026] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0027] In the following specific embodiments, parts are by mass. In this embodiment, it should be noted that the purchase manufacturers of all raw materials involved in the present invention are not subject to any special restrictions and illustratively include: tert-butyl alcohol has a CAS number of 75-65-0; di-tert-butyl dicarbonate has a CAS number of 24424-99-5; arginine has a CAS number of 74-79-3; EDC (1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride) has a CAS number of 7084-11-9; NHS (N-hydroxysuccinimide) has a CAS number of 6066-82-6; trifluoroacetic acid has a CAS number of 76-05-1; polylysine has a CAS number of 15 476, model is food grade; the CAS number of silver nitrate is 7761-88-8; the CAS number of octadecyltrimethoxysilane is 3069-42-9; the CAS number of 3-(2,3-epoxypropyloxy)propyltrimethoxysilane is 2530-83-8; the CAS number of 4-imidazole acrylic acid is 104-98-3; the product number of vinyl-terminated polydimethylsiloxane is SS8299, pharmaceutical grade; the CAS number of (3-aminopropyl)trimethoxysilane is 13822-56-5; the product number of nano zinc oxide is GH60002, specification is 50nm; the CAS number of glycidyl methacrylate is 106-91-2.

[0028] In the scheme, the preparation method of amino-type nano-zinc oxide is as follows: add 2 parts of nano-zinc oxide to an ethanol aqueous solution (the mass ratio of ethanol to deionized water is 3:5), ultrasonicate for 40 minutes, heat to 75°C, slowly add 10 parts of (3-aminopropyl)trimethoxysilane-ethanol aqueous solution (the concentration of (3-aminopropyl)trimethoxysilane is 3wt%), stir for 2.5 hours, cool to room temperature, centrifuge, wash, and dry to obtain amino-type nano-zinc oxide.

[0029] The preparation method of modified polylysine is as follows: under nitrogen protection, 0.55 parts of EDC and 0.32 parts of NHS are added to MES buffer (MES buffer concentration is 0.1M, pH is 5.5) and evenly mixed, 0.6 parts of Boc-arginine and 0.3 parts of caffeic acid are added under ice water bath and stirred for 35 minutes, 1.8 parts of polylysine are added and stirred for 5 hours, dialyzed for 2 days, freeze-dried, placed in 25wt% trifluoroacetic acid DCM system and stirred for 2 hours to remove the protecting group, the solvent is removed, washed and freeze-dried to obtain modified polylysine.

[0030] Example 1, a method for preparing a food-grade stainless steel straw with an antibacterial coating, comprising the following steps:

[0031] Step 1: Cut the food-grade stainless steel pipe into the required length, degrease and pickle it in turn to obtain the food-grade stainless steel straw substrate; place the food-grade stainless steel straw substrate in a 40°C electroplating solution for 45 seconds (6A / dm 2 ), obtaining a pre-plated food-grade stainless steel straw;

[0032] The raw materials of the electroplating solution include the following components: 25 g / L copper sulfate, 0.1 g / L modified polylysine, 2.5 g / L potassium chloride, and 0.03 mol / L hydrochloric acid, calculated by mass.

[0033] Step 2: Dipping the pre-plated food-grade stainless steel straw in the composite nanosilver sol for 40 seconds, removing and drying it to form an antibacterial layer; then transferring it to the modified polysiloxane slurry and dipping it for 50 seconds, removing and drying it to form a hydrophobic layer; thus, obtaining a food-grade stainless steel straw;

[0034] The preparation method of the composite nanosilver sol is as follows: (1) adding 0.3 parts of modified polylysine to deionized water, heating to 80°C, adding 1.2 parts of silver nitrate aqueous solution (concentration of 0.1M) and mixing evenly, adding 0.15 parts of sodium citrate solution (concentration of 0.12M) and 1.5 parts of sodium hydroxide aqueous solution (concentration of 1wt%), stirring for 1 hour, cooling to room temperature and standing to obtain a composite nanosilver sol;

[0035] The preparation method of modified polysiloxane slurry is as follows: (1) octadecyltrimethoxysilane and 3-(2,3-epoxypropoxy)propyltrimethoxysilane are added to anhydrous ethanol, mixed evenly, adjusted to pH 5, stirred at 60 ° C for 5 hours, and the solvent is removed to obtain branched polysiloxane; (2) 0.3 parts of 4-imidazole acrylic acid are added to acetone and mixed evenly, 1.5 parts of vinyl-terminated polydimethylsiloxane and 0.01 parts of AIBN are added and stirred evenly, the temperature is raised to 65 ° C and stirred for 2 hours, 0.2 parts of glycidyl methacrylate and 0.01 parts of AIBN are added and stirred for 3 hours, cooled to room temperature, added to cold ether and The modified polydimethylsiloxane was precipitated and weighed three times in a mixed solution of n-hexane (the volume ratio of cold ether and n-hexane was 1:3) to obtain a modified polydimethylsiloxane; (3) the modified polydimethylsiloxane, amino-type nano-zinc oxide, and branched polysiloxane were weighed in a mass ratio of 1:0.2:0.07; the amino-type nano-zinc oxide was ultrasonically dispersed in DMF, the modified polydimethylsiloxane was added, and the mixture was stirred at 55°C for 2 hours, the branched polysiloxane was added, and the mixture was stirred for 3 hours. The solvent was removed, and the mixture was washed and dried to obtain a modified polysiloxane; the modified polysiloxane was added to acetone and ultrasonically dispersed to obtain a modified polysiloxane slurry (the concentration of the modified polysiloxane was 8wt%).

[0036] Example 2, a method for preparing a food-grade stainless steel straw with an antibacterial coating, comprising the following steps:

[0037] Step 1: Cut the food-grade stainless steel pipe into the required length, degrease and pickle it in turn to obtain the food-grade stainless steel straw substrate; place the food-grade stainless steel straw substrate in a 40°C electroplating solution for 45 seconds (6A / dm 2 ), obtaining a pre-plated food-grade stainless steel straw;

[0038] The raw materials of the electroplating solution include the following components: 25 g / L copper sulfate, 0.1 g / L modified polylysine, 3 g / L potassium chloride, and 0.03 mol / L hydrochloric acid, calculated by mass.

[0039] Step 2: Dipping the pre-plated food-grade stainless steel straw in the composite nanosilver sol for 40 seconds, removing and drying it to form an antibacterial layer; then transferring it to the modified polysiloxane slurry and dipping it for 50 seconds, removing and drying it to form a hydrophobic layer; thus, obtaining a food-grade stainless steel straw;

[0040] The preparation method of the composite nanosilver sol is as follows: (1) adding 0.5 parts of modified polylysine to deionized water, heating to 80°C, adding 1.5 parts of silver nitrate aqueous solution (concentration of 0.1M) and mixing evenly, adding 0.15 parts of sodium citrate solution (concentration of 0.12M) and 1.5 parts of sodium hydroxide aqueous solution (concentration of 1wt%), stirring for 1 hour, cooling to room temperature and standing to obtain a composite nanosilver sol;

[0041] The preparation method of modified polysiloxane slurry is as follows: (1) octadecyltrimethoxysilane and 3-(2,3-epoxypropoxy)propyltrimethoxysilane are added to anhydrous ethanol, mixed evenly, adjusted to pH 5, stirred at 60°C for 5 hours, and the solvent is removed to obtain branched polysiloxane; (2) 0.3 parts of 4-imidazole acrylic acid are added to acetone and mixed evenly, 1.5 parts of vinyl-terminated polydimethylsiloxane and 0.01 parts of AIBN are added and stirred evenly, the temperature is raised to 65°C and stirred for 2 hours, 0.2 parts of glycidyl methacrylate and 0.01 parts of AIBN are added and stirred for 3 hours, and the mixture is cooled to room temperature. Add it to a mixed solution of cold ether and n-hexane for precipitation, repeat 3 times to obtain modified polydimethylsiloxane; (3) weigh the modified polydimethylsiloxane, amino-type nano-zinc oxide, and branched polysiloxane in a mass ratio of 1:0.3:0.07; ultrasonically disperse the amino-type nano-zinc oxide in DMF, add the modified polydimethylsiloxane, and stir at 55°C for 2 hours, add the branched polysiloxane and continue stirring for 3 hours, remove the solvent, wash and dry to obtain modified polysiloxane; add the modified polysiloxane to acetone for ultrasonic dispersion to obtain a modified polysiloxane slurry (the concentration of the modified polysiloxane is 12wt%).

[0042] Example 3, a method for preparing a food-grade stainless steel straw with an antibacterial coating, comprising the following steps:

[0043] Step 1: Cut the food-grade stainless steel pipe into the required length, degrease and pickle it in turn to obtain the food-grade stainless steel straw substrate; place the food-grade stainless steel straw substrate in a 40°C electroplating solution for 40 seconds (6A / dm 2 ), obtaining a pre-plated food-grade stainless steel straw;

[0044] The raw materials of the electroplating solution include the following components: 25 g / L copper sulfate, 0.1 g / L modified polylysine, 3 g / L potassium chloride, and 0.03 mol / L hydrochloric acid, calculated by mass.

[0045] Step 2: Dipping the pre-plated food-grade stainless steel straw in the composite nanosilver sol for 40 seconds, removing and drying it to form an antibacterial layer; then transferring it to the modified polysiloxane slurry and dipping it for 50 seconds, removing and drying it to form a hydrophobic layer; thus, obtaining a food-grade stainless steel straw;

[0046] The preparation method of the composite nanosilver sol is as follows: (1) adding 0.5 parts of modified polylysine to deionized water, heating to 80°C, adding 1.5 parts of silver nitrate aqueous solution (concentration of 0.1M) and mixing evenly, adding 0.15 parts of sodium citrate solution (concentration of 0.12M) and 1.5 parts of sodium hydroxide aqueous solution (concentration of 1wt%), stirring for 1 hour, cooling to room temperature and standing to obtain a composite nanosilver sol;

[0047] The preparation method of modified polysiloxane slurry is as follows: (1) octadecyltrimethoxysilane and 3-(2,3-epoxypropoxy)propyltrimethoxysilane are added to anhydrous ethanol, mixed evenly, adjusted to pH 5, stirred at 60°C for 5 hours, and the solvent is removed to obtain branched polysiloxane; (2) 0.3 parts of 4-imidazole acrylic acid are added to acetone and mixed evenly, 1.5 parts of vinyl-terminated polydimethylsiloxane and 0.01 parts of AIBN are added and stirred evenly, the temperature is raised to 65°C and stirred for 2 hours, 0.2 parts of glycidyl methacrylate and 0.01 parts of AIBN are added and stirred for 3 hours, and the mixture is cooled to room temperature. Add it to a mixed solution of cold ether and n-hexane for precipitation, repeat 3 times to obtain modified polydimethylsiloxane; (3) weigh the modified polydimethylsiloxane, amino-type nano-zinc oxide, and branched polysiloxane in a mass ratio of 1:0.2:0.07; ultrasonically disperse the amino-type nano-zinc oxide in DMF, add the modified polydimethylsiloxane, and stir at 55°C for 2 hours, add the branched polysiloxane and continue stirring for 3 hours, remove the solvent, wash and dry to obtain modified polysiloxane; add the modified polysiloxane to acetone for ultrasonic dispersion to obtain a modified polysiloxane slurry (the concentration of the modified polysiloxane is 10wt%).

[0048] Comparative Example 1 is based on Example 2, except that the super-hydrophobic layer is not introduced, and the remaining steps are the same;

[0049] Step 1: Cut the food-grade stainless steel pipe into the required length, degrease and pickle it in turn to obtain the food-grade stainless steel straw substrate; place the food-grade stainless steel straw substrate in a 40°C electroplating solution for 45 seconds (6A / dm 2 ), obtaining a pre-plated food-grade stainless steel straw;

[0050] Step 2: Immerse the pre-plated food-grade stainless steel straw in the composite nanosilver sol for 40 seconds, take it out and dry it to form an antibacterial layer to obtain a food-grade stainless steel straw.

[0051] Comparative Example 2 is based on Example 2, except that modified polylysine is not added to the composite nanosilver sol, and the remaining steps are the same;

[0052] Step 1: Cut the food-grade stainless steel pipe into the required length, degrease and pickle it in turn to obtain the food-grade stainless steel straw substrate; place the food-grade stainless steel straw substrate in a 40°C electroplating solution for 45 seconds (6A / dm 2 ), obtaining a pre-plated food-grade stainless steel straw;

[0053] Step 2: Dipping the pre-plated food-grade stainless steel straw in the composite nanosilver sol for 40 seconds, removing and drying it to form an antibacterial layer; then transferring it to the modified polysiloxane slurry and dipping it for 50 seconds, removing and drying it to form a hydrophobic layer; thus, obtaining a food-grade stainless steel straw;

[0054] The preparation method of nano silver sol is as follows: (1) heating deionized water to 80°C, adding 1.5 parts of silver nitrate aqueous solution (concentration of 0.1M) and mixing evenly, adding 0.15 parts of sodium citrate solution (concentration of 0.12M) and 1.5 parts of sodium hydroxide aqueous solution (concentration of 1wt%), stirring for 1 hour, cooling to room temperature and letting it stand to obtain nano silver sol.

[0055] Comparative Example 3 is based on Example 2, except that no branched polysiloxane is added, and the remaining steps are the same;

[0056] Step 1: Cut the food-grade stainless steel pipe into the required length, degrease and pickle it in turn to obtain the food-grade stainless steel straw substrate; place the food-grade stainless steel straw substrate in a 40°C electroplating solution for 45 seconds (6A / dm 2 ), obtaining a pre-plated food-grade stainless steel straw;

[0057] Step 2: Dipping the pre-plated food-grade stainless steel straw in the composite nanosilver sol for 40 seconds, removing and drying it to form an antibacterial layer; then transferring it to the modified polysiloxane slurry and dipping it for 50 seconds, removing and drying it to form a hydrophobic layer; thus, obtaining a food-grade stainless steel straw;

[0058] The preparation method of modified polysiloxane is as follows: (1) adding 0.3 parts of 4-imidazole acrylic acid to acetone and mixing evenly, adding 1.5 parts of vinyl-terminated polydimethylsiloxane and 0.01 parts of AIBN and stirring evenly, heating to 65°C and stirring for 2 hours, adding 0.2 parts of glycidyl methacrylate and 0.01 parts of AIBN and continuing stirring for 3 hours, cooling to room temperature, adding to a mixed solution of cold ether and n-hexane for precipitation, repeating 3 times to obtain modified polydimethylsiloxane; (2) weighing modified polydimethylsiloxane and amino-modified nano-zinc oxide in a mass ratio of 1:0.3; ultrasonically dispersing amino-modified nano-zinc oxide in DMF, adding modified polydimethylsiloxane, stirring at 55°C for 5 hours, removing the solvent, washing and drying to obtain modified polysiloxane; adding modified polysiloxane to acetone and ultrasonically dispersing to obtain modified polysiloxane slurry (the concentration of modified polysiloxane is 10wt%).

[0059] Comparative Example 4 is based on Example 2, except that electroplating was not performed and the remaining steps were the same;

[0060] The food-grade stainless steel pipe is cut into the required length, degreased and pickled in sequence to obtain a food-grade stainless steel straw substrate; the food-grade stainless steel straw substrate is first immersed in a composite nanosilver sol for 40 seconds, removed and dried to form an antibacterial layer; then transferred to a modified polysiloxane slurry and immersed for 50 seconds, removed and dried to form a hydrophobic layer; and a food-grade stainless steel straw is obtained.

[0061] Detection test: After soaking Examples 1 to 3 and Comparative Examples 1 to 4 in a household neutral detergent for 24 hours, rinsed with water and dried, the following experiment was carried out:

[0062] 1. Antibacterial property test: (1) The food-grade stainless steel straws with antibacterial coatings and the food-grade stainless steel straw substrates (as blank groups) prepared in Examples 1 to 3 and Comparative Examples 1 to 4 were cut into 5 mm × 5 mm samples respectively;

[0063] (2) Add the single colonies of Staphylococcus aureus and Escherichia coli to 50 mL of sterilized LB broth, add the samples in test (1), place them in a constant temperature shaker at 37°C and 160 rpm, and culture them until the logarithmic growth phase; take out the samples, rinse them repeatedly with sterilized PBS, place them in new 50 mL of LB broth (sterilized), and place them in a constant temperature shaker at 37°C and 160 rpm for 12 hours;

[0064] (3) Take 100 μL of each sample prepared in test (2) and spread it evenly on the solid culture medium, and then culture it for 12 hours; record the number of colonies, and calculate the sterilization rate based on the colony counts of Examples 1 to 3 and Comparative Examples 1 to 4 and the colony counts of the food-grade stainless steel straw substrate (as a blank group);

[0065] 2. Hydrophobicity test: The water contact angle (CA) and sliding angle (SA) of the hydrophobic coating surfaces of Example 2 and Comparative Example 2 were measured using a contact angle tester at room temperature. The contact angle of Example 2 was 158.5° and the sliding angle was 12.3°, while the contact angle of Comparative Example 3 was 147.6° and the sliding angle was 17.6°.

[0066]

[0067] Conclusion: Comparative Example 1 is based on Example 2, but no super-hydrophobic layer is introduced; this reduces the hydrophobicity of the stainless steel straw, allowing bacteria to grow in the pores of the stainless steel straw. As a result, the bacteria are not easily washed away during PBS cleaning, which results in a decrease in the performance of Comparative Example 1; Comparative Example 2 is based on Example 2, but no modified polylysine is added; this reduces the antibacterial performance of Comparative Example 2; Comparative Example 3 is based on Example 2, but no branched polysiloxane is added; this reduces the hydrophobicity, thereby reducing the antibacterial performance; Comparative Example 4 is based on Example 2, but no electroplating is performed, which reduces the adhesion of the nanosilver sol, thereby affecting the coating performance during long-term immersion.

[0068] 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 food-grade stainless steel straw with an antibacterial coating, characterized by: The following steps are included: Step 1: Cut the food-grade stainless steel pipe into the required length, degrease and pickle it in sequence to obtain a food-grade stainless steel straw substrate; place the food-grade stainless steel straw substrate in an electroplating solution for electroplating to obtain a pre-plated food-grade stainless steel straw; Step 2: Immerse the pre-plated food-grade stainless steel straw in the composite nanosilver sol for 40-60 seconds, remove and dry to form an antibacterial layer; Transfer the straw to a modified polysiloxane slurry and immerse for 30 to 50 seconds, then remove and dry it to form a hydrophobic layer; thereby obtaining a food-grade stainless steel straw. The raw materials of the electroplating solution include the following components: 20-25 g / L copper sulfate, 0.08-0.12 g / L modified polylysine, 2-3 g / L potassium chloride, and 0.03-0.05 mol / L hydrochloric acid, calculated by mass. The preparation method of the modified polysiloxane is as follows: (1) adding octadecyltrimethoxysilane and 3-(2,3-epoxypropoxy)propyltrimethoxysilane to anhydrous ethanol, uniformly mixing, adjusting the pH to 5-6, stirring at 60-70° C. for 4-5 hours, and removing the solvent to obtain a branched polysiloxane; (2) adding 4-imidazole acrylic acid to acetone, uniformly mixing, adding vinyl-terminated polydimethylsiloxane and AIBN, stirring uniformly, heating to 60-65° C. and stirring for 1- 2 hours, add glycidyl methacrylate and AIBN and continue stirring for 2-3 hours, cool to room temperature, add to a mixed solution of cold ether and n-hexane for precipitation, repeat 3-4 times to obtain modified polydimethylsiloxane; (3) ultrasonically disperse amino-modified nano-zinc oxide in DMF, add modified polydimethylsiloxane, stir at 50-60 ° C for 2-3 hours, add branched polysiloxane and continue stirring for 3-4 hours, remove the solvent, wash and dry to obtain modified polysiloxane; adding the modified polysiloxane into acetone and performing ultrasonic dispersion to obtain a modified polysiloxane slurry; The raw materials of the modified polydimethylsiloxane include the following components: 0.3-0.5 parts of 4-imidazole acrylic acid, 1-2 parts of vinyl-terminated polydimethylsiloxane, 0.2-0.3 parts of glycidyl methacrylate, and 0.01-0.02 parts of AIBN in parts by mass; the mass ratio of the modified polydimethylsiloxane, amino-modified nano-zinc oxide, and branched polysiloxane is 1:(0.2-0.3):(0.05-0.08); and the content of the modified polysiloxane in the modified polysiloxane slurry is 8-12 wt%.

2. The method for preparing a food-grade stainless steel straw with an antibacterial coating according to claim 1, characterized in that: The preparation method of the modified polylysine comprises: adding EDC and NHS to MES buffer under nitrogen protection and uniformly mixing; adding Boc-arginine and caffeic acid in an ice-water bath and stirring for 30-40 minutes; adding polylysine and stirring for 5-6 hours; dialyzing for 1-2 days; freeze-drying; placing in a 25-30 wt% trifluoroacetic acid in DCM system and stirring for 1-2 hours to remove the protecting group; removing the solvent; washing and freeze-drying to obtain the modified polylysine.

3. The method for preparing a food-grade stainless steel straw with an antibacterial coating according to claim 1, characterized in that: The raw materials of the modified polylysine include the following components: 1.5-2.5 parts of polylysine, 0.2-0.3 parts of caffeic acid, 0.4-0.7 parts of Boc-arginine, 0.5-0.55 parts of EDC, and 0.3-0.33 parts of NHS, calculated by mass; the concentration of the MES buffer is 0.1-0.12M, and the pH is 5-5.

5.

4. The method for preparing a food-grade stainless steel straw with an antibacterial coating according to claim 1, wherein: The preparation method of the composite nano silver sol comprises the following steps: adding modified polylysine to deionized water, heating the water to 70-90° C., adding a silver nitrate aqueous solution and uniformly mixing the mixture, adding a sodium citrate solution and a sodium hydroxide aqueous solution, stirring the mixture for 1-1.5 hours, cooling the mixture to room temperature and allowing the mixture to stand, thereby obtaining the composite nano silver sol.

5. The method for preparing a food-grade stainless steel straw with an antibacterial coating according to claim 1, characterized in that: The raw materials of the composite nano-silver sol include the following components: 0.3-0.5 parts of modified polylysine, 1-1.5 parts of silver nitrate aqueous solution, 0.12-0.15 parts of sodium citrate solution, and 1-3 parts of sodium hydroxide aqueous solution, calculated by mass. The concentration of the silver nitrate aqueous solution is 0.1-0.2M; the concentration of the sodium citrate solution is 0.1-0.15M; and the concentration of the sodium hydroxide aqueous solution is 1-2wt%.

6. The method for preparing a food-grade stainless steel straw with an antibacterial coating according to claim 1, characterized in that: The electroplating process conditions are: temperature 40~45℃, 4~6A / dm 2 The constant current time is 35~50s.

7. A food-grade stainless steel straw with an antibacterial coating is prepared according to the method for preparing a food-grade stainless steel straw with an antibacterial coating according to any one of claims 1 to 6.

Images