A production and processing technology for bamboo-like stainless steel guardrails

Abstract

The present invention relates to the technical field of stainless steel, specifically a production and processing technology for a bamboo-like stainless steel guardrail. The formed stainless steel guardrail is treated by spraying. By optimizing the protective coating, a bamboo paint layer and a protective layer are successively constructed on the surface of the stainless steel guardrail. A composite zinc-titanium hydrotalcite and double-bonded nano-silica are introduced as fillers into the protective coating. Using zinc acetate anhydrous, titanium tetrachloride, and dopamine hydrochloride as raw materials, zinc-titanium hydrotalcite coated with polydopamine is prepared by a hydrothermal method, and then an antibacterial and hydrophobic copolymer synthesized from 3-methacryloyldopamine, styrene, dodecafluoroheptyl methacrylate, dimethylaminoethyl methacrylate, and citronellyl methacrylate is deposited. An aqueous polyurethane emulsion is used as the base material of the photocurable protective coating.

Description

Technical Field

[0001] The present invention relates to the technical field of stainless steel, and specifically to a production and processing technology for bamboo-like stainless steel guardrails. Background Art

[0002] In the existing architectural designs of gardens and parks, bamboo is a commonly used and poetic decorative element. However, in actual applications, there are many difficulties in planting and transplanting real bamboo, which will affect the overall quality and ornamental effect of the architectural design.

[0003] To avoid problems such as transplanting live bamboo, bamboo-like processes have entered the market. Most of them are prepared by coating bamboo-like paint on metal materials, and there are also problems such as easy aging and peeling of the coating, which further accelerates the corrosion of the metal material. Summary of the Invention

[0004] The purpose of the present invention is to provide a production and processing technology for bamboo-like stainless steel guardrails to solve the problems in the prior art.

[0005] To solve the above technical problems, the present invention provides the following technical solutions:

[0006] A production and processing technology for bamboo-like stainless steel guardrails includes the following steps:

[0007] S1: Assemble and weld stainless steel pipes to form a stainless steel guardrail, and then perform sanding, polishing, washing, and drying to obtain a pretreated stainless steel guardrail;

[0008] S2: Coat bamboo-like paint on the surface of the pretreated stainless steel guardrail and dry it to form a bamboo paint layer;

[0009] S3: Mix aqueous polyurethane emulsion, composite zinc-titanium hydrotalcite, and double-bonded nano-silica, add a photoinitiator, and stir ultrasonically to obtain a protective coating;

[0010] S4: Coat the protective coating on the surface of the bamboo paint layer and perform photocuring treatment to form a protective layer, obtaining a bamboo-like stainless steel guardrail.

[0011] Further, by mass, the composition of the protective coating is: 31 - 57 parts of aqueous polyurethane emulsion, 1 - 2 parts of photoinitiator, 2 - 6 parts of composite zinc-titanium hydrotalcite, and 1 - 3 parts of double-bonded nano-silica.

[0012] Further, the mass ratio of composite zinc-titanium hydrotalcite to double-bonded nano-silica is 2:1.

[0013] Further, the working conditions of the photocuring treatment are: irradiating under 365 nm ultraviolet light for 5 - 10 min.

[0014] Furthermore, the preparation of double-bonded nano-silica includes the following steps: Mix nano-silica and isopropanol, add a mixed solution of vinyltrimethoxysilane, deionized water, and absolute ethanol, keep warm at 70 - 80 °C for 4 - 5 h, centrifuge, wash, and dry to obtain double-bonded nano-silica.

[0015] Furthermore, the preparation of composite zinc-titanium hydrotalcite includes the following steps:

[0016] (1) Mix zinc nitrate, ethanol, and deionized water, add titanium tetrachloride, add dopamine hydrochloride, after mixing, adjust the pH to 8, transfer to a reaction kettle, keep warm at 118 - 122 °C for 22 - 24 h, centrifuge, and wash 3 - 5 times with ethanol and deionized water in sequence to obtain polydopamine-coated zinc-titanium hydrotalcite;

[0017] (2) Mix polydopamine-coated zinc-titanium hydrotalcite, absolute ethanol, and deionized water, ultrasonically stir for 20 - 30 min, raise the temperature to 78 - 82 °C, add an antibacterial and hydrophobic copolymer, stir for 2 - 3 h, centrifuge, wash, dry, and grind to obtain composite zinc-titanium hydrotalcite.

[0018] Furthermore, the preparation of the aqueous polyurethane emulsion includes the following steps:

[0019] Under a nitrogen atmosphere, mix isophorone diisocyanate, polycarbonate diol, and dibutyltin dilaurate, raise the temperature to 63 - 68 °C and carry out an oil bath for 2 - 3 h, add a mixed solution of 2,2-dimethylolpropionic acid and acetone, raise the temperature to 78 - 82 °C and keep warm for 1 - 2 h, lower the temperature to 68 - 72 °C, add a mixed solution of castor oil and acetone, lower the temperature to 58 - 62 °C, add pentaerythritol triacrylate and an antibacterial and hydrophobic copolymer, continue to keep warm for 2 - 3 h, lower the temperature to 48 - 52 °C, add triethylamine, add deionized water for emulsification, and rotary evaporate to obtain an aqueous polyurethane emulsion with a solid content of 30 - 35%.

[0020] Furthermore, the mass ratio of isophorone diisocyanate, polycarbonate diol, 2,2-dimethylolpropionic acid, castor oil, pentaerythritol triacrylate, and the antibacterial and hydrophobic copolymer is 7:10:0.8:1.5:1:1.4.

[0021] Furthermore, the preparation of the antibacterial and hydrophobic copolymer includes the following steps:

[0022] 1) Under a nitrogen atmosphere, mix β-citronellol, triethylamine, and dichloromethane, transfer to an ice-water bath, add methacryloyl chloride, then keep warm at 18 - 25 °C for 7 - 8 h, perform suction filtration under reduced pressure, rotary evaporation for concentration, extract with ether 3 - 5 times, and perform extraction and washing with dilute hydrochloric acid and saturated sodium bicarbonate solution 1 - 3 times in sequence, then rotary evaporation for concentration, and purify through a silica gel column using n-hexane and ethyl acetate with a volume ratio of 9:1 as the eluent to obtain citronellyl methacrylate;

[0023] 2) Mix deionized water and sodium dodecyl sulfate, add acrylic acid, dodecafluoroheptyl methacrylate, dimethylaminoethyl methacrylate, citronellyl methacrylate, 3-methacryloyldopamine, stir for 20 - 30 min, add a mixed solution of potassium persulfate and deionized water, heat up to 78 - 82 °C and keep warm for 2 - 3 h, cool, centrifuge, wash, and dry to obtain an antibacterial and hydrophobic copolymer.

[0024] Compared with the prior art, the beneficial effects of the present invention are:

[0025] The present invention provides a production and processing process for a bamboo-like stainless steel guardrail. By optimizing the coating composition and processing technology, a bamboo-like stainless steel guardrail with superhydrophobicity, antibacterial property, ultraviolet resistance, and corrosion resistance is prepared, thereby greatly extending the service life of the bamboo-like stainless steel guardrail.

[0026] In the present invention, the formed stainless steel guardrail is treated by spraying. By optimizing the protective coating and then performing photocuring treatment, a bamboo paint layer and a protective layer are sequentially constructed on the surface of the stainless steel guardrail, thereby preventing the bamboo paint layer from falling off and greatly improving the appearance aesthetics and service durability of the stainless steel guardrail.

[0027] In order to endow the bamboo-like stainless steel guardrail with excellent ultraviolet resistance, the present invention introduces composite zinc-titanium hydrotalcite as a filler into the protective coating. Using zinc acetate anhydrous, titanium tetrachloride, and dopamine hydrochloride as raw materials, zinc-titanium hydrotalcite coated with polydopamine is prepared by a hydrothermal method. In order to improve the uniformity of the dispersion of the zinc-titanium hydrotalcite coated with polydopamine in the protective coating, using dopamine in the zinc-titanium hydrotalcite coated with polydopamine as an anchoring agent, deposit an antibacterial and hydrophobic copolymer synthesized from 3-methacryloyldopamine, styrene, dodecafluoroheptyl methacrylate, dimethylaminoethyl methacrylate, and citronellyl methacrylate. The dodecafluoroheptyl methacrylate in the copolymer endows it with a low surface energy, and the cationic monomer dimethylaminoethyl methacrylate and citronellyl methacrylate synergistically endow it with excellent antibacterial properties. Among them, citronellyl methacrylate is modified from the natural antibacterial agent citronellol through an esterification reaction; 3-methacryloyldopamine is beneficial for depositing the copolymer on the surface of the zinc-titanium hydrotalcite coated with polydopamine, thereby endowing the composite zinc-titanium hydrotalcite with excellent antibacterial and hydrophobic properties.

[0028] In order to improve the wear resistance of the protective layer, nano-silica is introduced as a filler into the protective coating. In order to improve the uniformity and firmness of the dispersion of nano-silica in the protective layer, vinyltrimethoxysilane is used to double bond it. By controlling the mass ratio of composite zinc-titanium hydrotalcite to double-bonded nano-silica in the coating, a superhydrophobic and wear-resistant surface of the protective layer is constructed, and the service durability of the bamboo-like stainless steel guardrail is improved.

[0029] In the present invention, an aqueous polyurethane emulsion is used as the base material of the photocurable protective coating. A prepolymer is prepared from isophorone diisocyanate and polycarbonate diol, dimethylolpropionic acid is used as the hydrophilic chain extender, castor oil is used as the internal crosslinking agent, and pentaerythritol triacrylate and an antibacterial and hydrophobic copolymer are used for end-capping modification, which greatly improves the bonding strength between the coating and the stainless steel guardrail, improves the hydrophobicity and antibacterial property of the coating, and prolongs the service life of the stainless steel guardrail. Specific embodiments

[0030] The following will clearly and completely describe the technical solutions in the present invention in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0031] It should be noted that if there are directional indications such as up, down, left, right, front, and back in the embodiments of the present invention, the directional indications are only used to explain the relative position relationship and movement conditions between components in a specific posture. If the specific posture changes, the directional indications will also change accordingly. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the fact that those of ordinary skill in the art can implement it. When the combination of technical solutions results in contradictions or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the protection scope required by the present invention.

[0032] The following further details the technical solutions of the present invention in conjunction with specific embodiments. It should be understood that the following embodiments are only used to explain the present invention and are not used to limit the present invention.

[0033] Embodiment 1: A production and processing process for a bamboo-like stainless steel guardrail includes the following steps:

[0034] S1: Assemble and weld the stainless steel pipes to form a stainless steel guardrail, and then perform sanding, polishing, washing, and drying to obtain a pretreated stainless steel guardrail;

[0035] S2: Coat the surface of the pretreated stainless steel guardrail with bamboo-like paint and dry it to form a bamboo paint layer;

[0036] S3: Mix the aqueous polyurethane emulsion, composite zinc-titanium hydrotalcite, and double-bonded nano-silica, add a photoinitiator, and stir ultrasonically to obtain a protective coating;

[0037] By mass, the composition of the protective coating is: 31 parts of aqueous polyurethane emulsion, 1 part of photoinitiator, 2 parts of composite zinc-titanium hydrotalcite, and 1 part of double-bonded nano-silica;

[0038] The mass ratio of composite zinc-titanium hydrotalcite to double-bonded nano-silica is 2:1;

[0039] The preparation of the double-bonded nano-silica includes the following steps: Mix 2 g of nano-silica and 80 mL of isopropanol, add a mixture of 1.2 g of vinyltrimethoxysilane, 6 mL of deionized water, and 44 mL of absolute ethanol, keep at 70 °C for 5 h, centrifuge, wash, and dry to obtain double-bonded nano-silica;

[0040] The preparation of the composite zinc-titanium hydrotalcite includes the following steps:

[0041] (1) Mix 3.7 g of zinc nitrate, 400 mL of ethanol, and 400 mL of deionized water, add 1.1 mL of titanium tetrachloride, add 0.4 g of hydrochloric acid dopamine, adjust the pH to 8, transfer to a reaction kettle, keep at 118 °C for 24 h, centrifuge, and wash 3 times with ethanol and deionized water in turn to obtain polydopamine-coated zinc-titanium hydrotalcite;

[0042] (2) Mix 1.2 g of polydopamine-coated zinc-titanium hydrotalcite, 60 mL of absolute ethanol, and 60 mL of deionized water, stir ultrasonically for 20 min, heat up to 78 °C, add 1.8 g of antibacterial hydrophobic copolymer, stir for 2 h, centrifuge, wash, dry, and grind to obtain composite zinc-titanium hydrotalcite;

[0043] The preparation of the aqueous polyurethane emulsion includes the following steps:

[0044] Under a nitrogen atmosphere, add 7 g of isophorone diisocyanate, 10 g of polycarbonate diol, and 3 drops of dibutyltin dilaurate, heat up to 63 °C in an oil bath for 3 h, add a mixture of 0.8 g of 2,2-dimethylolpropionic acid and 5 mL of acetone, heat up to 78 °C and keep for 2 h, cool down to 68 °C, add 2.8 g of castor oil and 5 mL of acetone, cool down to 58 °C, add 1 g of pentaerythritol triacrylate and 1.4 g of antibacterial hydrophobic copolymer, continue to keep for 2 h, cool down to 48 °C, add 0.8 g of triethylamine, emulsify with deionized water, and rotary evaporate to obtain an aqueous polyurethane emulsion with a solid content of 33%;

[0045] The preparation of the antibacterial hydrophobic copolymer includes the following steps:

[0046] 1) Under a nitrogen atmosphere, 9.1 mL of β-citronellol, 8.3 mL of triethylamine, and 100 mL of dichloromethane were mixed, transferred to an ice-water bath, 5.8 mL of methacryloyl chloride was added, and then it was kept at 18 °C for 8 h. It was filtered by suction under reduced pressure and concentrated by rotary evaporation, extracted with ether three times, and successively extracted and washed once with dilute hydrochloric acid and saturated sodium bicarbonate solution, and then concentrated by rotary evaporation. It was purified by passing through a silica gel column with n-hexane and ethyl acetate in a volume ratio of 9:1 as the eluent to obtain citronellyl methacrylate;

[0047] 2) 20 mL of deionized water and 0.5 g of sodium dodecyl sulfate were mixed, 3 g of styrene, 4.5 g of dodecafluoroheptyl methacrylate, 1.5 g of dimethylaminoethyl methacrylate, 1.1 g of citronellyl methacrylate, and 1.2 g of 3-methacryloyldopamine were added, stirred for 20 min, and then a mixed solution of 0.6 g of potassium persulfate and 20 mL of deionized water was added. The temperature was raised to 78 °C and kept for 3 h, cooled, centrifuged, washed, and dried to obtain an antibacterial and hydrophobic copolymer;

[0048] S4: The protective coating was applied to the surface of the bamboo paint layer and subjected to photocuring treatment to form a protective layer, obtaining a bamboo-like stainless steel guardrail; the working conditions for the photocuring treatment were: irradiating under 365 nm ultraviolet light for 8 min.

[0049] Example 2: A production and processing process for a bamboo-like stainless steel guardrail, comprising the following steps:

[0050] S1: The stainless steel pipes were assembled and welded into shape to obtain a stainless steel guardrail, and then it was sanded, polished, washed, and dried to obtain a pretreated stainless steel guardrail;

[0051] S2: The bamboo-like paint was applied to the surface of the pretreated stainless steel guardrail and dried to form a bamboo paint layer;

[0052] S3: An aqueous polyurethane emulsion, composite zinc-titanium hydrotalcite, and double-bonded nano-silica were mixed, and a photoinitiator was added, followed by ultrasonic stirring to obtain a protective coating;

[0053] By mass, the composition of the protective coating was: 43 parts of aqueous polyurethane emulsion, 1.5 parts of photoinitiator, 4 parts of composite zinc-titanium hydrotalcite, and 2 parts of double-bonded nano-silica;

[0054] The mass ratio of composite zinc-titanium hydrotalcite to double-bonded nano-silica was 2:1;

[0055] The preparation of the double-bonded nano-silica included the following steps: 2 g of nano-silica and 80 mL of isopropanol were mixed, and a mixed solution of 1.2 g of vinyltrimethoxysilane, 6 mL of deionized water, and 44 mL of absolute ethanol was added, and it was kept at 75 °C for 4.5 h, centrifuged, washed, and dried to obtain double-bonded nano-silica;

[0056] The preparation of the composite zinc-titanium hydrotalcite comprises the following steps:

[0057] (1) Mix 3.7 g of zinc nitrate, 400 mL of ethanol, and 400 mL of deionized water, add 1.1 mL of titanium tetrachloride, add 0.4 g of hydrochloric acid dopamine, adjust the pH to 8 after mixing, transfer to a reaction kettle, keep warm at 120 °C for 23 h, centrifuge, and wash 4 times with ethanol and deionized water in sequence to obtain polydopamine-coated zinc-titanium hydrotalcite;

[0058] (2) Mix 1.2 g of polydopamine-coated zinc-titanium hydrotalcite, 60 mL of absolute ethanol, and 60 mL of deionized water, stir ultrasonically for 25 min, raise the temperature to 80 °C, add 1.8 g of antibacterial hydrophobic copolymer, stir for 2.5 h, centrifuge, wash, dry, and grind to obtain composite zinc-titanium hydrotalcite;

[0059] The preparation of the aqueous polyurethane emulsion comprises the following steps:

[0060] Under a nitrogen atmosphere, mix 7 g of isophorone diisocyanate, 10 g of polycarbonate diol, and 3 drops of dibutyltin dilaurate, raise the temperature to 65 °C and carry out an oil bath for 2.5 h, add a mixture of 0.8 g of 2,2-dimethylolpropionic acid and 5 mL of acetone, raise the temperature to 80 °C and keep warm for 1.5 h, lower the temperature to 70 °C, add 2.8 g of castor oil and 5 mL of acetone, lower the temperature to 60 °C, add 1 g of pentaerythritol triacrylate and 1.4 g of antibacterial hydrophobic copolymer, continue to keep warm for 2.5 h, lower the temperature to 50 °C, add 0.8 g of triethylamine, add deionized water for emulsification, and carry out rotary evaporation to obtain an aqueous polyurethane emulsion with a solid content of 33%;

[0061] The preparation of the antibacterial hydrophobic copolymer comprises the following steps:

[0062] 1) Under a nitrogen atmosphere, mix 9.1 mL of β-citronellol, 8.3 mL of triethylamine, and 100 mL of dichloromethane, transfer to an ice-water bath, add 5.8 mL of methacryloyl chloride, then keep warm at 20 °C for 7.5 h, carry out vacuum filtration and rotary evaporation concentration, extract 4 times with ether, carry out extraction and washing 2 times with dilute hydrochloric acid and saturated sodium bicarbonate solution in sequence, carry out rotary evaporation concentration, and purify by passing through a silica gel column with a volume ratio of 9:1 of n-hexane and ethyl acetate as the eluent to obtain citronellyl methacrylate;

[0063] 2) Mix 20 mL of deionized water and 0.5 g of sodium dodecyl sulfate, add 3 g of styrene, 4.5 g of dodecafluorooctyl methacrylate, 1.5 g of dimethylaminoethyl methacrylate, 1.1 g of citronellyl methacrylate, and 1.2 g of 3-methacryloyldopamine, stir for 25 min, add a mixture of 0.6 g of potassium persulfate and 20 mL of deionized water, heat to 80 °C and keep warm for 2.5 h, cool, centrifuge, wash, and dry to obtain an antibacterial and hydrophobic copolymer;

[0064] S4: Coating the protective coating on the surface of the bamboo paint layer, and performing photocuring treatment to form a protective layer, thereby obtaining a bamboo-like stainless steel guardrail; the working conditions of the photocuring treatment are: irradiating under ultraviolet light of 365 nm for 5 - 10 min.

[0065] Example 3: A production and processing process of a bamboo-like stainless steel guardrail, comprising the following steps:

[0066] S1: Assemble and weld the stainless steel pipes to form a stainless steel guardrail, and then perform sanding, polishing, washing, and drying to obtain a pretreated stainless steel guardrail;

[0067] S2: Coat the bamboo-like paint on the surface of the pretreated stainless steel guardrail and dry it to form a bamboo paint layer;

[0068] S3: Mix an aqueous polyurethane emulsion, a composite zinc-titanium hydrotalcite, and a double-bonded nano-silica, add a photoinitiator, and perform ultrasonic stirring to obtain a protective coating;

[0069] By mass, the composition of the protective coating is: 57 parts of aqueous polyurethane emulsion, 2 parts of photoinitiator, 6 parts of composite zinc-titanium hydrotalcite, and 3 parts of double-bonded nano-silica;

[0070] The mass ratio of the composite zinc-titanium hydrotalcite to the double-bonded nano-silica is 2:1;

[0071] The preparation of the double-bonded nano-silica includes the following steps: Mix 2 g of nano-silica and 80 mL of isopropyl alcohol, add a mixture of 1.2 g of vinyltrimethoxysilane, 6 mL of deionized water, and 44 mL of absolute ethanol, keep warm at 80 °C for 4 h, centrifuge, wash, and dry to obtain double-bonded nano-silica;

[0072] The preparation of the composite zinc-titanium hydrotalcite includes the following steps:

[0073] (1) Mix 3.7 g of zinc nitrate, 400 mL of ethanol, and 400 mL of deionized water, add 1.1 mL of titanium tetrachloride, add 0.4 g of dopamine hydrochloride and mix, adjust the pH to 8, transfer to a reaction kettle, keep warm at 122 °C for 22 h, centrifuge, and wash 5 times with ethanol and deionized water in sequence to obtain poly-dopamine-coated zinc-titanium hydrotalcite;

[0074] (2) Mix 1.2 g of polydopamine-coated zinc-titanium hydrotalcite, 60 mL of absolute ethanol, and 60 mL of deionized water, ultrasonically stir for 30 min, heat up to 82 °C, add 1.8 g of antibacterial hydrophobic copolymer, stir for 3 h, centrifuge, wash, dry, and grind to obtain composite zinc-titanium hydrotalcite;

[0075] The preparation of the aqueous polyurethane emulsion includes the following steps:

[0076] Under a nitrogen atmosphere, heat 7 g of isophorone diisocyanate, 10 g of polycarbonate diol, and 3 drops of dibutyltin dilaurate to 68 °C and perform an oil bath for 2 h. Add a mixture of 0.8 g of 2,2-dimethylolpropionic acid and 5 mL of acetone, heat up to 82 °C and keep warm for 1 h, cool down to 72 °C, add 2.8 g of castor oil and 5 mL of acetone, cool down to 62 °C, add 1 g of pentaerythritol triacrylate and 1.4 g of antibacterial hydrophobic copolymer, continue to keep warm for 3 h, cool down to 52 °C, add 0.8 g of triethylamine, add deionized water for emulsification, and perform rotary evaporation to obtain an aqueous polyurethane emulsion with a solid content of 33%;

[0077] The preparation of the antibacterial hydrophobic copolymer includes the following steps:

[0078] 1) Under a nitrogen atmosphere, mix 9.1 mL of β-citronellol, 8.3 mL of triethylamine, and 100 mL of dichloromethane, transfer to an ice-water bath, add 5.8 mL of methacryloyl chloride, then keep warm at 25 °C for 8 h, perform vacuum filtration and rotary evaporation concentration, extract 5 times with diethyl ether, and perform extraction and washing 3 times successively with dilute hydrochloric acid and saturated sodium bicarbonate solution, then perform rotary evaporation concentration, and purify through a silica gel column using a mixture of n-hexane and ethyl acetate with a volume ratio of 9:1 as the eluent to obtain citronellyl methacrylate;

[0079] 2) Mix 20 mL of deionized water and 0.5 g of sodium dodecyl sulfate, add 3 g of styrene, 4.5 g of dodecafluoroheptyl methacrylate, 1.5 g of dimethylaminoethyl methacrylate, 1.1 g of citronellyl methacrylate, and 1.2 g of 3-methacryloyldopamine, stir for 20 - 30 min, add a mixture of 0.6 g of potassium persulfate and 20 mL of deionized water, heat up to 82 °C and keep warm for 2 h, cool, centrifuge, wash, and dry to obtain the antibacterial hydrophobic copolymer;

[0080] S4: Coat the protective coating on the surface of the bamboo paint layer, perform photocuring treatment to form a protective layer, and obtain a bamboo-like stainless steel guardrail; the working conditions for the photocuring treatment are: irradiate under ultraviolet light of 365 nm for 8 min.

[0081] Comparative Example 1: Using Example 3 as the control group, replace the composite zinc-titanium hydrotalcite with polydopamine-coated zinc-titanium hydrotalcite, and the other processes are normal.

[0082] Comparative Example 2: Taking Example 3 as the control group, the aqueous polyurethane (BZ-7: Changzhou Baichang Coating Technology Co., Ltd.) was replaced with an aqueous polyurethane emulsion, and other processes were normal.

[0083] Comparative Example 3: Taking Example 3 as the control group, the antibacterial hydrophobic copolymer was not prepared, and other processes were normal.

[0084] The thicknesses of both the bamboo paint layer and the protective layer are 20 µm.

[0085] Sources of raw materials used (only as a demonstration example):

[0086] Imitation bamboo paint: Wuhu Coating Chemical Industry Co., Ltd., Ningjin County, Shandong Province; Stainless steel pipe: In terms of mass percentage, its chemical composition is: carbon 0.008%, silicon 0.323%, manganese 1.12%, chromium 17.11%, nickel 10.45%, molybdenum 2.07%, and the balance is iron; Photoinitiator 2959S60365: Shanghai Yuanye Bio-Technology Co., Ltd.; 3-Methacryloyldopamine A0915896: Henan Wheat Chemical Technology Co., Ltd.; Polycarbonate diol QF0424: Hubei Qifei Pharmaceutical and Chemical Industry Co., Ltd.; Nano-silica S490064, Vinyltrimethoxysilane V162969, Zinc nitrate Z190758, Dopamine hydrochloride D103111, Isophorone diisocyanate I109582, Dibutyltin dilaurate D100274, Castor oil C110663, 2,2-Dimethylolpropionic acid B104539, Pentaerythritol triacrylate P189117, β-Citronellol C102066, Triethylamine T103285, Methacryloyl chloride M109517, Styrene S110375, Dodecafluoroheptyl methacrylate D301595, Dimethylaminoethyl methacrylate D111129, Sodium dodecyl sulfate S108347: Aladdin reagents; Isopropanol, Absolute ethanol, Titanium tetrachloride, Acetone, Dichloromethane, Ether, Hydrochloric acid, Sodium bicarbonate, n-Hexane, Ethyl acetate, Potassium persulfate, analytically pure: Reagents of Sinopharm Group.

[0087] Performance test: The stainless steel guardrails prepared in the examples and comparative examples were tested:

[0088] Antibacterial property: Escherichia coli was used as the test strain, and the plate method was used for testing; Hydrophobicity: It was characterized by the water contact angle, and a 4 μL deionized water droplet was tested with a tester; UV resistance: The bamboo-proof stainless steel guardrail was irradiated with 365 nm ultraviolet light for 3 days, and then the antibacterial property was tested. Compared with the sample without ultraviolet irradiation, if the antibacterial change rate was 0-1% (including 1%), it was considered excellent, otherwise it was unqualified; The obtained results are shown in Table 1;

[0089] Table 1

[0090]

[0091] The present invention provides a production and processing technology for bamboo-like stainless steel guardrails. By optimizing the coating composition and processing technology, a bamboo-like stainless steel guardrail with superhydrophobic, antibacterial, ultraviolet-resistant, and corrosion-resistant properties is prepared, thereby significantly extending the service life of the bamboo-like stainless steel guardrail.

[0092] Comparing Example 3 with Comparative Example 1 and Comparative Example 3, it can be seen that in order to endow the bamboo-like stainless steel guardrail with excellent ultraviolet resistance, the present invention introduces composite zinc-titanium hydrotalcite as a filler into the protective coating. Using zinc acetate anhydrous, titanium tetrachloride, and dopamine hydrochloride as raw materials, zinc-titanium hydrotalcite coated with polydopamine was prepared by a hydrothermal method. In order to improve the uniformity of the dispersion of the polydopamine-coated zinc-titanium hydrotalcite in the protective coating, using dopamine in the polydopamine-coated zinc-titanium hydrotalcite as an anchoring agent, an antibacterial and hydrophobic copolymer synthesized from 3-methacryloyldopamine, styrene, dodecafluoroheptyl methacrylate, dimethylaminoethyl methacrylate, and citronellyl methacrylate was deposited. The dodecafluoroheptyl methacrylate in the copolymer imparts low surface energy to it, and the cationic monomer dimethylaminoethyl methacrylate and citronellyl methacrylate synergistically impart excellent antibacterial properties to it. Among them, citronellyl methacrylate is modified from the natural antibacterial agent citronellol through an esterification reaction; 3-methacryloyldopamine is beneficial to deposit the copolymer on the surface of the polydopamine-coated zinc-titanium hydrotalcite, thereby endowing the composite zinc-titanium hydrotalcite with excellent antibacterial and hydrophobic properties.

[0093] Comparing Example 3 with Comparative Example 2 and Comparative Example 3, it can be seen that in the present invention, an aqueous polyurethane emulsion is used as the base material of the photocurable protective coating. A prepolymer is prepared using isophorone diisocyanate and polycarbonate diol as raw materials, 2,2-dimethylolpropionic acid is used as a hydrophilic chain extender, castor oil is used as an internal crosslinking agent, and pentaerythritol triacrylate and the antibacterial and hydrophobic copolymer are used for end-capping modification, significantly improving the bonding strength between the coating and the stainless steel guardrail, enhancing the hydrophobicity and antibacterial properties of the coating, and extending the service life of the stainless steel guardrail.

[0094] The above are only the embodiments of the present invention, and do not limit the patent scope of the present invention accordingly. All equivalent structural transformations made using the specification of the present invention under the inventive concept of the present invention, or direct / indirect applications in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A production and processing technology of imitation bamboo stainless steel guardrail, characterized in that: The following steps are involved: S1: Assemble and weld the stainless steel pipes to obtain the stainless steel guardrail, and then perform grinding, polishing, washing and drying to obtain the pre-treated stainless steel guardrail; S2: applying the imitation bamboo paint on the surface of the pretreated stainless steel guardrail, drying it, and forming a bamboo paint layer; S3: mixing the waterborne polyurethane emulsion, the composite zinc-titanium hydrotalcite and the double-bonded nano-silica, adding a photoinitiator, and ultrasonically stirring to obtain a protective coating; S4: coating the protective coating on the surface of the bamboo paint layer, and performing light curing to form a protective layer, thereby obtaining a bamboo-like stainless steel guardrail; The preparation of the composite zinc-titanium hydrotalcite comprises the following steps: (1) Mix zinc nitrate, ethanol and deionized water, add titanium tetrachloride, add dopamine hydrochloride and mix, adjust the pH to 8, transfer to a reactor, keep warm at 118-122°C for 22-24 hours, centrifuge, wash with ethanol and deionized water for 3-5 times, and obtain polydopamine-coated zinc-titanium hydrotalcite; (2) Mixing the polydopamine-coated zinc-titanium hydrotalcite, anhydrous ethanol and deionized water, stirring with ultrasound for 20-30 min, heating to 78-82° C., adding the antibacterial hydrophobic copolymer, stirring for 2-3 h, centrifuging, washing, drying and grinding to obtain a composite zinc-titanium hydrotalcite; The preparation of the aqueous polyurethane emulsion comprises the following steps: In a nitrogen atmosphere, isophorone diisocyanate, polycarbonate diol and dibutyltin dilaurate are mixed, the temperature is raised to 63-68°C in an oil bath for 2-3 hours, a mixed solution of 2,2-dihydroxymethylpropionic acid and acetone is added, the temperature is raised to 78-82°C and kept warm for 1-2 hours, the temperature is lowered to 68-72°C, a mixed solution of castor oil and acetone is added, the temperature is lowered to 58-62°C, pentaerythritol triacrylate and antibacterial hydrophobic copolymer are added, the temperature is kept warm for 2-3 hours, the temperature is lowered to 48-52°C, triethylamine is added, deionized water is added for emulsification, and rotary evaporation is performed to obtain an aqueous polyurethane emulsion; The preparation of the antibacterial hydrophobic copolymer comprises the following steps: 1) Under a nitrogen atmosphere, β-citronellol, triethylamine and dichloromethane were mixed, transferred to an ice-water bath, methacryloyl chloride was added, and then kept at 18-25°C for 7-8h, filtered under reduced pressure, concentrated by rotary evaporation, extracted with ether for 3-5 times, extracted and washed with dilute hydrochloric acid and saturated sodium bicarbonate solution for 1-3 times, concentrated by rotary evaporation, and purified by silica gel column using n-hexane and ethyl acetate in a volume ratio of 9:1 as eluent to obtain citronellol methyl methacrylate; 2) Mix deionized water and sodium dodecyl sulfate, add styrene, dodecafluoroheptyl methacrylate, dimethylaminoethyl methacrylate, citronellyl methyl methacrylate, and 3-methacryloyl dopamine, stir for 20-30 minutes, add a mixture of potassium persulfate and deionized water, heat to 78-82° C. and keep warm for 2-3 hours, cool, centrifuge, wash, and dry to obtain an antibacterial hydrophobic copolymer.

2. The production and processing technology of the bamboo-like stainless steel guardrail according to claim 1 is characterized in that: The protective coating comprises, by weight, 31-57 parts of aqueous polyurethane emulsion, 1-2 parts of photoinitiator, 2-6 parts of composite zinc-titanium hydrotalcite, and 1-3 parts of double-bonded nano-silicon dioxide.

3. The production and processing technology of the bamboo-like stainless steel guardrail according to claim 1 is characterized in that: The mass ratio of the composite zinc-titanium hydrotalcite to the double-bonded nano-silica is 2:

1.

4. The production and processing technology of the bamboo-like stainless steel guardrail according to claim 1 is characterized in that: The working conditions of the light curing treatment are: irradiation under 365nm ultraviolet light for 5-10min.

5. The production and processing technology of the bamboo-like stainless steel guardrail according to claim 1 is characterized in that: The preparation of the double-bonded nano-silica comprises the following steps: mixing nano-silica and isopropanol, adding a mixed solution of vinyltrimethoxysilane, deionized water and anhydrous ethanol, keeping warm at 70-80°C for 4-5h, centrifuging, washing and drying to obtain the double-bonded nano-silica.

6. The production and processing technology of the bamboo-like stainless steel guardrail according to claim 1 is characterized in that: In the preparation of the aqueous polyurethane emulsion, the mass ratio of isophorone diisocyanate, polycarbonate diol, 2,2-dihydroxymethyl propionic acid, castor oil, pentaerythritol triacrylate, and antibacterial hydrophobic copolymer is 7:10:0.8:1.5:1:1.

4.

7. A bamboo-like stainless steel guardrail, characterized in that: The product is obtained by the process described in any one of claims 1 to 6.

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