A high-strength steel pipe based on hot-dip galvanizing and its preparation process

Abstract

The present invention relates to the technical field of metal surface treatment, specifically a high-strength steel pipe based on hot-dip galvanizing and a preparation process thereof. The present invention first performs hot-dip galvanizing treatment on the steel pipe, and then sprays a passivating agent for treatment; the passivating agent is compounded by a composite coating, an amine curing agent, and water; in the composite coating, an epoxy-modified acrylic resin is polymerized by methyl methacrylate, 4-epoxyisoeugenol, and butyl acrylate, and a silicone oil-modified epoxy resin is first reacted with hydroxy silicone oil and isophorone diisocyanate to generate terminal isocyanate silicone oil, and then reacted with an isocyanate group and a hydroxyl group in an epoxy resin to obtain; under the action of an amine curing agent, cross-linking occurs between the epoxy-modified acrylic resin and the silicone oil-modified epoxy resin, thereby forming a dense protective layer. The process of the present invention can effectively protect the hot-dip galvanized steel pipe from corrosion and improve the service life of the steel pipe.

Description

Technical Field

[0001] The invention relates to the technical field of metal surface treatment, in particular to a high-strength steel pipe based on hot-dip galvanizing and a preparation process thereof. Background Art

[0002] Hot-dip galvanizing is a method of first cleaning and degreasing the surface of steel materials, and then immersing the activated steel materials into molten liquid zinc to form a metallurgical bonding coating on the surface of steel materials in the form of dissolution, chemical reaction and diffusion. The zinc layer not only has the function of isolating the protected material, but also has cathodic protection, so its advantage is that it can form a double layer of protection on the surface of steel materials. The hot-dip galvanizing coating obtained by hot-dip galvanizing can last for several years or even more than ten years, thus protecting steel parts from rust. However, during transportation and storage, steel parts are exposed to industrial atmosphere or marine climate for a long time, and are extremely susceptible to chemical corrosion or electrochemical corrosion. Even if hot-dip galvanizing is performed on the surface of steel parts, when the steel parts are transported and stored for a long time, micro-batteries are prone to form zinc hydroxide on the surface of steel parts, and white rust spots appear; in addition, bacteria in soil, seawater and other environments can also corrode steel materials, affecting the quality and strength of steel, and thus affecting the performance of steel. Summary of the invention

[0003] The object of the present invention is to provide a high-strength steel pipe based on hot-dip galvanizing and a preparation process thereof to solve the problems raised in the above background technology.

[0004] In order to solve the above technical problems, the present invention provides the following technical solutions: a high-strength steel pipe based on hot-dip galvanizing and a preparation process thereof, comprising the following steps:

[0005] Step 1:

[0006] S11: mixing methyl methacrylate, 4-epoxyisoeugenol and butyl acrylate to obtain a mixed monomer;

[0007] S12: Weigh azobisisobutyronitrile and dissolve it in butyl acetate to obtain an initiator solution;

[0008] S13: Divide the initiator solution and the mixed monomer into 3-4 equal parts by weight, add 1 part of the initiator solution and 1 part of the mixed monomer to butyl acetate in a water bath at 70-80° C., keep the temperature for reaction, and then add 1 part of the initiator solution and 1 part of the mixed monomer every 15-20 minutes. After all the additions are completed, keep the temperature for reaction for 1-2 hours to obtain an epoxy-modified acrylic resin;

[0009] Step 2:

[0010] S21: adding isophorone diisocyanate to hydroxy silicone oil at 60-70°C under nitrogen protection, and reacting for 2-3 hours to obtain terminal isocyanate silicone oil;

[0011] S22: adding terminal isocyanate silicone oil dropwise into the epoxy resin at 35-45° C.; stirring and reacting for 6-8 hours to obtain silicone oil-modified epoxy resin;

[0012] Step 3:

[0013] S31: mixing epoxy-modified acrylic resin and silicone oil-modified epoxy resin to obtain a composite coating;

[0014] S32: mixing the composite coating, the amine curing agent, and deionized water to obtain a passivating agent;

[0015] Step 4:

[0016] S41: The surface of the steel pipe is alkali-washed, pickled and washed with water; the cleaned steel pipe is immersed in a plating solution for 1 to 3 minutes, taken out and dried, and then immersed in a galvanizing solution for hot-dip galvanizing for 3 to 5 minutes, purged with steam at a temperature of 120 to 140°C and a pressure of 0.5 to 0.7 MPa for 10 to 20 seconds, and cooled to obtain a hot-dip galvanized steel pipe;

[0017] S42: The passivating agent is sprayed on the surface of the hot-dip galvanized steel pipe and cured at 80-90°C to form a coating of 200-500 μm to obtain a high-strength steel pipe.

[0018] Furthermore, in S11, the contents of the components in the mixed monomer are, by weight percentage, 50-60% of methyl methacrylate, 5-10% of 4-epoxyisoeugenol, and 30-45% of butyl acrylate.

[0019] Furthermore, in S12, the contents of the components in the initiator solution are, by weight, 0.4 to 5 parts of azobisisobutyronitrile and 40 to 50 parts of butyl acetate.

[0020] Furthermore, in S21, hydroxy silicone oil and isophorone diisocyanate are reacted at a molar ratio of hydroxyl group to isocyanate group of 1:1.

[0021] Furthermore, in S21, the molecular weight of the hydroxy silicone oil is 500-1000.

[0022] Furthermore, in S22, the amount of the terminal isocyanate silicone oil added is 10-15% of the total weight of the epoxy resin.

[0023] Furthermore, in S31, the content of each component in the composite coating, by weight percentage, is 12-18% of epoxy-modified acrylic resin and 82-88% of silicone oil-modified epoxy resin.

[0024] Furthermore, in S32, the contents of the components in the passivating agent are, by weight, 100-120 parts of the composite coating, 30-40 parts of the curing agent, and 100-150 parts of deionized water.

[0025] Further, in S41, the alkaline washing solution is a sodium hydroxide solution with a concentration of 80~100g / L; the pickling solution is a hydrochloric acid solution with a concentration of 60~120g / L; the content of ammonium chloride in the plating solution is 280~300g / L, the content of zinc chloride is 280~320g / L, and the balance is water; the content of each component in the galvanizing solution is calculated by weight percentage, 0.1~0.5% aluminum, 0.3~0.5% magnesium, 0.005~0.01% steel, 0.1~0.3% lanthanum, 0.02~0.1% silicon, and the balance is zinc.

[0026] Compared with the prior art, the beneficial effect achieved by the present invention is as follows: by adopting the technical scheme of the present invention, the steel pipe is first cleaned to remove the dirt on its surface, and then the cleaned steel pipe is subjected to plating assistance treatment and hot-dip galvanizing treatment, and finally sprayed with a passivating agent to obtain a corrosion-resistant steel pipe. After the hot-dip galvanizing process, the coating forms a dense coating film on the surface of the steel pipe; the coating is further treated with a passivating agent to form a protective layer on the surface of the coating, which can further protect the steel pipe from corrosion. In the present invention, the passivating agent is mainly obtained by mixing epoxy-modified acrylic resin and silicone oil-modified epoxy resin, and then compounding with a curing agent and water; wherein, the epoxy-modified acrylic resin is polymerized by methyl methacrylate, 4-epoxyisoeugenol, and butyl acrylate, and the silicone oil-modified epoxy resin is firstly generated by reacting hydroxy silicone oil with isophorone diisocyanate at a molar ratio of 1:1 between hydroxyl and isocyanate groups to generate terminal isocyanate silicone oil, and then grafting is performed by reacting the isocyanate group with the hydroxyl group in the epoxy resin.

[0027] 4-Epoxyisoeugenol in epoxy-modified acrylic resin, as a derivative of eugenol, has certain antibacterial properties and can reduce the adverse effects of bacterial corrosion on materials; the hydrophobicity of epoxy resin modified by hydroxy silicone oil is improved, and water droplets or humid gases are difficult to stay on the surface of the steel pipe, avoiding the occurrence of corrosion on the metal surface caused by long-term contact; in addition, epoxy-modified acrylic resin can improve the bonding performance of epoxy resin. Under the action of amine curing agent, the epoxy group undergoes a ring-opening reaction, so that the epoxy-modified acrylic resin and the silicone oil-modified epoxy resin form a cross-linked structure, thereby forming a dense protective layer, making it easier to combine with the coating on the surface of the steel pipe to form a strong bonding interface. Epoxy-modified acrylic resin can improve the chemical resistance of epoxy resin, making it more resistant to corrosion, solvents and chemical erosion, and enhancing the service life and performance stability of the material in harsh environments.

[0028] It should be noted that when using hydroxy silicone oil to modify epoxy resin, using low molecular weight hydroxy silicone oil with a molecular weight of 500~1000 can avoid the viscosity of the hydroxy silicone oil being too high, which will affect the modification effect; and when preparing the passivator, in order to avoid the problem of poor interface compatibility after blending the epoxy-modified acrylic resin and the silicone oil-modified epoxy resin, the best effect is achieved by mixing 12~18% epoxy-modified acrylic resin and 82~88% silicone oil-modified epoxy resin by weight, and then compounding with the curing agent and deionized water. DETAILED DESCRIPTION

[0029] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] Materials used in the present invention and their sources: hydroxy silicone oil comes from Anhui Aiyota Silicone Oil Co., Ltd., with a molecular weight of 1000 and a hydroxyl content of 8.5-10%; the amine curing agent is triethylenetetramine, which comes from Aladdin Chemical Reagent; and the epoxy resin is epoxy resin E51, which comes from Baling Petrochemical, with a product number of CYD-128.

[0031] Embodiment 1: A high-strength steel pipe based on hot-dip galvanizing and a preparation process thereof, comprising the following steps:

[0032] Step 1:

[0033] S11: 60% of methyl methacrylate, 10% of 4-epoxyisoeugenol, and 30% of butyl acrylate are mixed by weight to obtain a mixed monomer;

[0034] S12: Weigh 5 g of azobisisobutyronitrile and dissolve it in 50 g of butyl acetate to obtain an initiator solution;

[0035] S13: Divide the initiator solution and the mixed monomer into three equal parts by weight, add 1 part of the initiator solution and 1 part of the mixed monomer to butyl acetate in a water bath at 70° C., keep the temperature for reaction, and then add 1 part of the initiator solution and 1 part of the mixed monomer every 15 minutes. After all the additions are completed, keep the temperature for reaction for 1 hour to obtain an epoxy-modified acrylic resin; wherein the weight ratio of the initiator solution to the mixed monomer is 1:10;

[0036] Step 2:

[0037] S21: at 60° C. and in a nitrogen atmosphere, isophorone diisocyanate is added to the hydroxy silicone oil in a molar ratio of isocyanate group to hydroxyl group of 1:1, and the reaction is carried out at this temperature for 2 hours to obtain an isocyanate-terminated silicone oil;

[0038] S22: at 35° C., adding terminal isocyanate silicone oil dropwise into the epoxy resin, wherein the amount of the terminal isocyanate silicone oil added is 10% of the weight of the epoxy resin; stirring the reaction for 6 hours to obtain a silicone oil-modified epoxy resin;

[0039] Step 3:

[0040] S31: 12% epoxy modified acrylic resin and 88% silicone oil modified epoxy resin are mixed to obtain a composite coating by weight percentage;

[0041] S32: 120 g of the composite coating, 40 g of an amine curing agent, and 150 g of deionized water are mixed to obtain a passivating agent;

[0042] Step 4:

[0043] S41: The surface of the steel pipe is alkali-washed, pickled and washed with water; the cleaned steel pipe is immersed in the plating solution for 1 minute, taken out and dried, and then immersed in the galvanizing solution for hot-dip galvanizing for 3 minutes, purged with steam at a temperature of 120°C and a pressure of 0.5MPa for 10 seconds, and cooled to obtain a hot-dip galvanized steel pipe; wherein the alkali washing solution is a sodium hydroxide solution with a concentration of 100g / L, and the pickling solution is a hydrochloric acid solution with a concentration of 120g / L; the content of ammonium chloride in the plating solution is 280g / L, the content of zinc chloride is 280g / L, and the balance is water; the content of each component in the galvanizing solution, by weight percentage, is 0.5% aluminum, 0.5% magnesium, 0.01% steel, 0.1% lanthanum, 0.1% silicon, and the balance is zinc;

[0044] S42: Spray the passivating agent onto the surface of the hot-dip galvanized steel pipe and solidify it at 80°C to form a coating with a thickness of 200 μm to obtain a high-strength steel pipe.

[0045] Embodiment 2: A high-strength steel pipe based on hot-dip galvanizing and a preparation process thereof, comprising the following steps:

[0046] Step 1:

[0047] S11: 60% of methyl methacrylate, 10% of 4-epoxyisoeugenol, and 30% of butyl acrylate are mixed by weight to obtain a mixed monomer;

[0048] S12: Weigh 5 g of azobisisobutyronitrile and dissolve it in 50 g of butyl acetate to obtain an initiator solution;

[0049] S13: Divide the initiator solution and the mixed monomer into three equal parts by weight, add 1 part of the initiator solution and 1 part of the mixed monomer to butyl acetate in a water bath at 75° C., keep the temperature for reaction, and then add 1 part of the initiator solution and 1 part of the mixed monomer every 15 minutes. After all the additions are completed, keep the temperature for reaction for 1.5 hours to obtain an epoxy-modified acrylic resin; wherein the weight ratio of the initiator solution to the mixed monomer is 1:10;

[0050] Step 2:

[0051] S21: at 65° C. and in a nitrogen atmosphere, isophorone diisocyanate was added to the hydroxy silicone oil in a molar ratio of isocyanate group to hydroxyl group of 1:1, and the reaction was carried out at this temperature for 2.5 hours to obtain an isocyanate-terminated silicone oil;

[0052] S22: at 40° C., adding terminal isocyanate silicone oil dropwise into the epoxy resin, wherein the amount of the terminal isocyanate silicone oil added is 10% of the weight of the epoxy resin; stirring the reaction for 7 hours to obtain a silicone oil-modified epoxy resin;

[0053] Step 3:

[0054] S31: 12% epoxy modified acrylic resin and 88% silicone oil modified epoxy resin are mixed to obtain a composite coating by weight percentage;

[0055] S32: 120 g of the composite coating, 40 g of an amine curing agent, and 150 g of deionized water are mixed to obtain a passivating agent;

[0056] Step 4:

[0057] S41: The surface of the steel pipe is alkali-washed, pickled and washed with water; the cleaned steel pipe is immersed in a plating solution for 2 minutes, taken out and dried, and then immersed in a galvanizing solution for hot-dip galvanizing for 4 minutes, purged with steam at a temperature of 130°C and a pressure of 0.6MPa for 15 seconds, and cooled to obtain a hot-dip galvanized steel pipe; wherein the alkali washing solution is a sodium hydroxide solution with a concentration of 100g / L, and the pickling solution is a hydrochloric acid solution with a concentration of 120g / L; the content of ammonium chloride in the plating solution is 280g / L, the content of zinc chloride is 280g / L, and the balance is water; the content of each component in the galvanizing solution, by weight percentage, is 0.5% aluminum, 0.5% magnesium, 0.01% steel, 0.1% lanthanum, 0.1% silicon, and the balance is zinc;

[0058] S42: Spray the passivating agent onto the surface of the hot-dip galvanized steel pipe and solidify it at 85°C to form a coating with a thickness of 200 μm to obtain a high-strength steel pipe.

[0059] Embodiment 3: A high-strength steel pipe based on hot-dip galvanizing and a preparation process thereof, comprising the following steps:

[0060] Step 1:

[0061] S11: 60% of methyl methacrylate, 10% of 4-epoxyisoeugenol, and 30% of butyl acrylate are mixed by weight to obtain a mixed monomer;

[0062] S12: Weigh 5 g of azobisisobutyronitrile and dissolve it in 50 g of butyl acetate to obtain an initiator solution;

[0063] S13: Divide the initiator solution and the mixed monomer into three equal parts by weight, add 1 part of the initiator solution and 1 part of the mixed monomer to butyl acetate in a water bath at 80° C., keep the temperature for reaction, and then add 1 part of the initiator solution and 1 part of the mixed monomer every 15 minutes. After all the additions are completed, keep the temperature for reaction for 2 hours to obtain an epoxy-modified acrylic resin; wherein the weight ratio of the initiator solution to the mixed monomer is 1:10;

[0064] Step 2:

[0065] S21: at 70° C. and in a nitrogen atmosphere, isophorone diisocyanate is added to the hydroxy silicone oil in a molar ratio of isocyanate group to hydroxyl group of 1:1, and the reaction is carried out for 3 hours to obtain an isocyanate-terminated silicone oil;

[0066] S22: at 45° C., adding terminal isocyanate silicone oil dropwise into the epoxy resin, wherein the amount of the terminal isocyanate silicone oil added is 10% of the weight of the epoxy resin; stirring and reacting for 8 hours to obtain a silicone oil-modified epoxy resin;

[0067] Step 3:

[0068] S31: 12% epoxy modified acrylic resin and 88% silicone oil modified epoxy resin are mixed to obtain a composite coating by weight percentage;

[0069] S32: 120 g of the composite coating, 40 g of an amine curing agent, and 150 g of deionized water are mixed to obtain a passivating agent;

[0070] Step 4:

[0071] S41: The surface of the steel pipe is alkali-washed, pickled and washed with water; the cleaned steel pipe is immersed in a plating solution for 3 minutes, taken out and dried, and then immersed in a galvanizing solution for hot-dip galvanizing for 5 minutes, purged with steam at a temperature of 140°C and a pressure of 0.7MPa for 20 seconds, and cooled to obtain a hot-dip galvanized steel pipe; wherein the alkali washing solution is a sodium hydroxide solution with a concentration of 100g / L, and the pickling solution is a hydrochloric acid solution with a concentration of 120g / L; the content of ammonium chloride in the plating solution is 280g / L, the content of zinc chloride is 280g / L, and the balance is water; the content of each component in the galvanizing solution, by weight percentage, is 0.5% aluminum, 0.5% magnesium, 0.01% steel, 0.1% lanthanum, 0.1% silicon, and the balance is zinc;

[0072] S42: Spray the passivating agent onto the surface of the hot-dip galvanized steel pipe and solidify it at 90°C to form a coating with a thickness of 200 μm to obtain a high-strength steel pipe.

[0073] Embodiment 4: A high-strength steel pipe based on hot-dip galvanizing and a preparation process thereof, comprising the following steps:

[0074] Step 1:

[0075] S11: 60% of methyl methacrylate, 10% of 4-epoxyisoeugenol, and 30% of butyl acrylate are mixed by weight to obtain a mixed monomer;

[0076] S12: Weigh 5 g of azobisisobutyronitrile and dissolve it in 50 g of butyl acetate to obtain an initiator solution;

[0077] S13: Divide the initiator solution and the mixed monomer into three equal parts by weight, add 1 part of the initiator solution and 1 part of the mixed monomer to butyl acetate in a water bath at 70° C., keep the temperature for reaction, and then add 1 part of the initiator solution and 1 part of the mixed monomer every 20 minutes. After all the additions are completed, keep the temperature for reaction for 2 hours to obtain an epoxy-modified acrylic resin; wherein the weight ratio of the initiator solution to the mixed monomer is 1:10;

[0078] Step 2:

[0079] S21: at 65° C. and in a nitrogen atmosphere, isophorone diisocyanate is added to the hydroxy silicone oil in a molar ratio of isocyanate group to hydroxyl group of 1:1, and the reaction is carried out at this temperature for 2 hours to obtain an isocyanate-terminated silicone oil;

[0080] S22: at 35° C., adding terminal isocyanate silicone oil dropwise into the epoxy resin, wherein the amount of the terminal isocyanate silicone oil added is 10% of the weight of the epoxy resin; stirring and reacting for 6 hours to obtain a silicone oil-modified epoxy resin;

[0081] Step 3:

[0082] S31: 14% epoxy modified acrylic resin and 86% silicone oil modified epoxy resin are mixed to obtain a composite coating, by weight percentage;

[0083] S32: 120 g of the composite coating, 40 g of an amine curing agent, and 150 g of deionized water are mixed to obtain a passivating agent;

[0084] Step 4:

[0085] S41: The surface of the steel pipe is alkali-washed, pickled and washed with water; the cleaned steel pipe is immersed in a plating solution for 3 minutes, taken out and dried, and then immersed in a galvanizing solution for hot-dip galvanizing for 5 minutes, purged with steam at a temperature of 120°C and a pressure of 0.5MPa for 10 seconds, and cooled to obtain a hot-dip galvanized steel pipe; wherein the alkali washing solution is a sodium hydroxide solution with a concentration of 100g / L, and the pickling solution is a hydrochloric acid solution with a concentration of 120g / L; the content of ammonium chloride in the plating solution is 280g / L, the content of zinc chloride is 280g / L, and the balance is water; the content of each component in the galvanizing solution, by weight percentage, is 0.5% aluminum, 0.5% magnesium, 0.01% steel, 0.1% lanthanum, 0.1% silicon, and the balance is zinc;

[0086] S42: Spray the passivating agent onto the surface of the hot-dip galvanized steel pipe and solidify it at 90°C to form a coating with a thickness of 200 μm to obtain a high-strength steel pipe.

[0087] Embodiment 5: A high-strength steel pipe based on hot-dip galvanizing and a preparation process thereof, comprising the following steps:

[0088] Step 1:

[0089] S11: 60% of methyl methacrylate, 10% of 4-epoxyisoeugenol, and 30% of butyl acrylate are mixed by weight to obtain a mixed monomer;

[0090] S12: Weigh 5 g of azobisisobutyronitrile and dissolve it in 50 g of butyl acetate to obtain an initiator solution;

[0091] S13: Divide the initiator solution and the mixed monomer into 4 equal parts by weight, add 1 part of the initiator solution and 1 part of the mixed monomer to butyl acetate in a water bath at 75° C., keep the temperature for reaction, and then add 1 part of the initiator solution and 1 part of the mixed monomer every 15 minutes. After all the additions are completed, keep the temperature for reaction for 2 hours to obtain an epoxy-modified acrylic resin; wherein the weight ratio of the initiator solution to the mixed monomer is 1:10;

[0092] Step 2:

[0093] S21: at 70° C. and in a nitrogen atmosphere, isophorone diisocyanate is added to the hydroxy silicone oil in a molar ratio of isocyanate group to hydroxyl group of 1:1, and the reaction is carried out for 3 hours to obtain an isocyanate-terminated silicone oil;

[0094] S22: at 45° C., adding terminal isocyanate silicone oil dropwise into the epoxy resin, wherein the amount of the terminal isocyanate silicone oil added is 10% of the weight of the epoxy resin; stirring and reacting for 8 hours to obtain a silicone oil-modified epoxy resin;

[0095] Step 3:

[0096] S31: 16% epoxy modified acrylic resin and 84% silicone oil modified epoxy resin are mixed to obtain a composite coating, by weight percentage;

[0097] S32: 120 g of the composite coating, 40 g of an amine curing agent, and 150 g of deionized water are mixed to obtain a passivating agent;

[0098] Step 4:

[0099] S41: The surface of the steel pipe is alkali-washed, pickled and washed with water; the cleaned steel pipe is immersed in the plating solution for 1 minute, taken out and dried, and then immersed in the galvanizing solution for hot-dip galvanizing for 5 minutes, purged with steam at a temperature of 140°C and a pressure of 0.5MPa for 20 seconds, and cooled to obtain a hot-dip galvanized steel pipe; wherein the alkali washing solution is a sodium hydroxide solution with a concentration of 100g / L, and the pickling solution is a hydrochloric acid solution with a concentration of 120g / L; the content of ammonium chloride in the plating solution is 280g / L, the content of zinc chloride is 280g / L, and the balance is water; the content of each component in the galvanizing solution, by weight percentage, is 0.5% aluminum, 0.5% magnesium, 0.01% steel, 0.1% lanthanum, 0.1% silicon, and the balance is zinc;

[0100] S42: Spray the passivating agent onto the surface of the hot-dip galvanized steel pipe and solidify it at 80°C to form a coating with a thickness of 200 μm to obtain a high-strength steel pipe.

[0101] Embodiment 6: A high-strength steel pipe based on hot-dip galvanizing and a preparation process thereof, comprising the following steps:

[0102] Step 1:

[0103] S11: 60% of methyl methacrylate, 10% of 4-epoxyisoeugenol, and 30% of butyl acrylate are mixed by weight to obtain a mixed monomer;

[0104] S12: Weigh 5 g of azobisisobutyronitrile and dissolve it in 50 g of butyl acetate to obtain an initiator solution;

[0105] S13: Divide the initiator solution and the mixed monomer into 4 equal parts by weight, add 1 part of the initiator solution and 1 part of the mixed monomer to butyl acetate in a water bath at 80° C., keep the temperature for reaction, and then add 1 part of the initiator solution and 1 part of the mixed monomer every 20 minutes. After all the additions are completed, keep the temperature for reaction for 2 hours to obtain an epoxy-modified acrylic resin; wherein the weight ratio of the initiator solution to the mixed monomer is 1:10;

[0106] Step 2:

[0107] S21: at 70° C. and in a nitrogen atmosphere, isophorone diisocyanate is added to the hydroxy silicone oil in a molar ratio of isocyanate group to hydroxyl group of 1:1, and the reaction is carried out for 3 hours to obtain an isocyanate-terminated silicone oil;

[0108] S22: at 45° C., adding terminal isocyanate silicone oil dropwise into the epoxy resin, wherein the amount of the terminal isocyanate silicone oil added is 10% of the weight of the epoxy resin; stirring and reacting for 8 hours to obtain a silicone oil-modified epoxy resin;

[0109] Step 3:

[0110] S31: 18% epoxy modified acrylic resin and 82% silicone oil modified epoxy resin are mixed to obtain a composite coating, by weight percentage;

[0111] S32: 120 g of the composite coating, 40 g of an amine curing agent, and 150 g of deionized water are mixed to obtain a passivating agent;

[0112] Step 4:

[0113] S41: The surface of the steel pipe is alkali-washed, pickled and washed with water; the cleaned steel pipe is immersed in a plating solution for 3 minutes, taken out and dried, and then immersed in a galvanizing solution for hot-dip galvanizing for 5 minutes, purged with steam at a temperature of 140°C and a pressure of 0.7MPa for 20 seconds, and cooled to obtain a hot-dip galvanized steel pipe; wherein the alkali washing solution is a sodium hydroxide solution with a concentration of 100g / L, and the pickling solution is a hydrochloric acid solution with a concentration of 120g / L; the content of ammonium chloride in the plating solution is 280g / L, the content of zinc chloride is 280g / L, and the balance is water; the content of each component in the galvanizing solution, by weight percentage, is 0.5% aluminum, 0.5% magnesium, 0.01% steel, 0.1% lanthanum, 0.1% silicon, and the balance is zinc;

[0114] S42: Spray the passivating agent onto the surface of the hot-dip galvanized steel pipe and solidify it at 90°C to form a coating with a thickness of 200 μm to obtain a high-strength steel pipe.

[0115] Comparative Example 1: No passivating agent was sprayed, and the other parameters were the same as those in Example 1.

[0116] The surface of the steel pipe is alkali-washed, pickled and washed with water; the cleaned steel pipe is immersed in the plating solution for 1 minute, taken out and dried, and then immersed in the galvanizing solution for hot-dip galvanizing for 3 minutes, purged with steam at a temperature of 120°C and a pressure of 0.5MPa for 10 seconds, and cooled to obtain a hot-dip galvanized steel pipe; wherein the alkali washing solution is a sodium hydroxide solution with a concentration of 100g / L, and the pickling solution is a hydrochloric acid solution with a concentration of 120g / L; the content of ammonium chloride in the plating solution is 280g / L, the content of zinc chloride is 280g / L, and the balance is water; the content of each component in the galvanizing solution, by weight percentage, is 0.5% aluminum, 0.5% magnesium, 0.01% steel, 0.1% lanthanum, 0.1% silicon, and the balance is zinc.

[0117] Comparative Example 2: The epoxy resin was not modified with hydroxy silicone oil, and the other parameters were the same as those in Example 2.

[0118] Step 1:

[0119] S11: 60% of methyl methacrylate, 10% of 4-epoxyisoeugenol, and 30% of butyl acrylate are mixed by weight to obtain a mixed monomer;

[0120] S12: Weigh 5 g of azobisisobutyronitrile and dissolve it in 50 g of butyl acetate to obtain an initiator solution;

[0121] S13: Divide the initiator solution and the mixed monomer into three equal parts by weight, add 1 part of the initiator solution and 1 part of the mixed monomer to butyl acetate in a water bath at 75° C., keep the temperature for reaction, and then add 1 part of the initiator solution and 1 part of the mixed monomer every 15 minutes. After all the additions are completed, keep the temperature for reaction for 1.5 hours to obtain an epoxy-modified acrylic resin; wherein the weight ratio of the initiator solution to the mixed monomer is 1:10;

[0122] Step 2:

[0123] S21: 12% epoxy-modified acrylic resin and 88% epoxy resin are mixed to obtain a composite coating, based on weight percentage;

[0124] S22: 120 g of the composite coating, 40 g of the amine curing agent, and 150 g of deionized water are mixed to obtain a passivating agent;

[0125] Step 3:

[0126] S31: The surface of the steel pipe is alkali-washed, pickled and washed with water; the cleaned steel pipe is immersed in a plating solution for 2 minutes, taken out and dried, and then immersed in a galvanizing solution for hot-dip galvanizing for 4 minutes, purged with steam at a temperature of 130°C and a pressure of 0.6MPa for 15 seconds, and cooled to obtain a hot-dip galvanized steel pipe; wherein the alkali washing solution is a sodium hydroxide solution with a concentration of 100g / L, and the pickling solution is a hydrochloric acid solution with a concentration of 120g / L; the content of ammonium chloride in the plating solution is 280g / L, the content of zinc chloride is 280g / L, and the balance is water; the content of each component in the galvanizing solution, by weight percentage, is 0.5% aluminum, 0.5% magnesium, 0.01% steel, 0.1% lanthanum, 0.1% silicon, and the balance is zinc;

[0127] S32: spraying the passivating agent on the surface of the hot-dip galvanized steel pipe, curing at 85°C to form a coating with a thickness of 200 μm, and obtaining a high-strength steel pipe.

[0128] Comparative Example 3: The amount of epoxy-modified acrylic resin in the composite coating was increased, and the other parameters were the same as those in Example 3.

[0129] Step 1:

[0130] S11: 60% of methyl methacrylate, 10% of 4-epoxyisoeugenol, and 30% of butyl acrylate are mixed by weight to obtain a mixed monomer;

[0131] S12: Weigh 5 g of azobisisobutyronitrile and dissolve it in 50 g of butyl acetate to obtain an initiator solution;

[0132] S13: Divide the initiator solution and the mixed monomer into three equal parts by weight, add 1 part of the initiator solution and 1 part of the mixed monomer to butyl acetate in a water bath at 80° C., keep the temperature for reaction, and then add 1 part of the initiator solution and 1 part of the mixed monomer every 15 minutes. After all the additions are completed, keep the temperature for reaction for 2 hours to obtain an epoxy-modified acrylic resin; wherein the weight ratio of the initiator solution to the mixed monomer is 1:10;

[0133] Step 2:

[0134] S21: at 70° C. and in a nitrogen atmosphere, isophorone diisocyanate is added to the hydroxy silicone oil in a molar ratio of isocyanate group to hydroxyl group of 1:1, and the reaction is carried out for 3 hours to obtain an isocyanate-terminated silicone oil;

[0135] S22: at 45° C., adding terminal isocyanate silicone oil dropwise into the epoxy resin, wherein the amount of the terminal isocyanate silicone oil added is 10% of the weight of the epoxy resin; stirring and reacting for 8 hours to obtain a silicone oil-modified epoxy resin;

[0136] Step 3:

[0137] S31: 20% epoxy modified acrylic resin and 80% silicone oil modified epoxy resin are mixed to obtain a composite coating by weight percentage;

[0138] S32: 120 g of the composite coating, 40 g of an amine curing agent, and 150 g of deionized water are mixed to obtain a passivating agent;

[0139] Step 4:

[0140] S41: The surface of the steel pipe is alkali-washed, pickled and washed with water; the cleaned steel pipe is immersed in a plating solution for 3 minutes, taken out and dried, and then immersed in a galvanizing solution for hot-dip galvanizing for 5 minutes, purged with steam at a temperature of 140°C and a pressure of 0.7MPa for 20 seconds, and cooled to obtain a hot-dip galvanized steel pipe; wherein the alkali washing solution is a sodium hydroxide solution with a concentration of 100g / L, and the pickling solution is a hydrochloric acid solution with a concentration of 120g / L; the content of ammonium chloride in the plating solution is 280g / L, the content of zinc chloride is 280g / L, and the balance is water; the content of each component in the galvanizing solution, by weight percentage, is 0.5% aluminum, 0.5% magnesium, 0.01% steel, 0.1% lanthanum, 0.1% silicon, and the balance is zinc;

[0141] S42: Spray the passivating agent onto the surface of the hot-dip galvanized steel pipe and solidify it at 90°C to form a coating with a thickness of 200 μm to obtain a high-strength steel pipe.

[0142] Experiment: The following experimental tests were carried out on Examples 1 to 6 and Comparative Examples 1 to 3, and the test results are shown in the following table; wherein,

[0143] Salt spray resistance test: refer to GB / T 10125-2021, use continuous spray test for 200h, observe the area of ​​"white rust", and refer to GB / T 6461-2002 to grade the plated parts after the test; the rating from best to worst is 10~0;

[0144] Passivation agent film adhesion test: Use a 5cm wide tape to wrap around the steel pipe, stick it and pull it down at a constant speed, and use the cross-hatch method to calculate the ratio of the area of ​​the film layer falling off to the area of ​​the entire area; the larger the ratio, the worse the adhesion;

[0145] Hydrophobicity: The passivating agents in Examples 1 to 6 and Comparative Examples 2 to 3 were sprayed on the surface of the steel plate material, and the contact angle was tested;

[0146]

[0147] Conclusion: The data of Examples 1 to 6 show that after the passivator prepared in this application is cured, a film layer with good hydrophobic effect is formed on the surface of the hot-dip galvanized steel pipe, and the adhesion effect between the film layer and the steel pipe is good, which can effectively prevent the steel pipe from being corroded. The data of Example 1 and Comparative Example 1 show that the passivator in Example 1 has a good protective effect on the steel pipe, and the salt spray corrosion resistance effect is obvious; the data of Example 2 and Comparative Example 2 show that in Example 2, the passivator is prepared by modifying the epoxy resin with hydroxy silicone oil, and the film layer formed on the surface of the steel pipe has good hydrophobicity, which reduces the contact between water vapor and chemical components and the surface of the steel pipe to a certain extent, so the appearance rating of the steel pipe in the salt spray test is higher; the data of Example 3 and Comparative Example 3 show that in the passivator of Comparative Example 3, the content of epoxy-modified acrylic resin is too high, which will cause the compatibility of epoxy-modified acrylic resin with epoxy resin to deteriorate, so the corrosion resistance and adhesion effect are not as good as those of Example 3.

[0148] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is 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 can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A preparation process of a high-strength steel pipe based on hot-dip galvanizing, characterized in that: The following steps are involved: Step 1: S11: mixing methyl methacrylate, 4-epoxyisoeugenol and butyl acrylate to obtain a mixed monomer; S12: Weigh azobisisobutyronitrile and dissolve it in butyl acetate to obtain an initiator solution; S13: Divide the initiator solution and the mixed monomer into 3-4 equal parts by weight, add 1 part of the initiator solution and 1 part of the mixed monomer to butyl acetate in a water bath at 70-80° C., keep the temperature for reaction, and then add 1 part of the initiator solution and 1 part of the mixed monomer every 15-20 minutes. After all the additions are completed, keep the temperature for reaction for 1-2 hours to obtain an epoxy-modified acrylic resin; Step 2: S21: adding isophorone diisocyanate to hydroxy silicone oil at 60-70°C under nitrogen protection, and reacting for 2-3 hours to obtain terminal isocyanate silicone oil; S22: adding terminal isocyanate silicone oil dropwise into the epoxy resin at 35-45° C.; stirring and reacting for 6-8 hours to obtain silicone oil-modified epoxy resin; Step 3: S31: mixing epoxy-modified acrylic resin and silicone oil-modified epoxy resin to obtain a composite coating; S32: mixing the composite coating, the amine curing agent, and deionized water to obtain a passivating agent; Step 4: S41: The surface of the steel pipe is alkali-washed, pickled and washed with water; the cleaned steel pipe is immersed in a plating solution for 1 to 3 minutes, taken out and dried, and then immersed in a galvanizing solution for hot-dip galvanizing for 3 to 5 minutes, purged with steam at a temperature of 120 to 140°C and a pressure of 0.5 to 0.7 MPa for 10 to 20 seconds, and cooled to obtain a hot-dip galvanized steel pipe; S42: spraying a passivating agent on the surface of the hot-dip galvanized steel pipe and curing it at 80-90° C. to obtain a high-strength steel pipe; In S32, the contents of the components in the passivating agent are, by weight, 100-120 parts of the composite coating, 30-40 parts of the curing agent, and 100-150 parts of deionized water.

2. The process for preparing a high-strength steel pipe based on hot-dip galvanizing according to claim 1, characterized in that: In S11, the contents of the components in the mixed monomer are, by weight percentage, 50-60% methyl methacrylate, 5-10% 4-epoxyisoeugenol, and 30-45% butyl acrylate.

3. The process for preparing a high-strength steel pipe based on hot-dip galvanizing according to claim 1, characterized in that: In S12, the content of each component in the initiator solution is, by weight, 0.4-5 parts of azobisisobutyronitrile and 40-50 parts of butyl acetate.

4. The process for preparing a high-strength steel pipe based on hot-dip galvanizing according to claim 1, characterized in that: In S21, hydroxy silicone oil and isophorone diisocyanate are reacted at a molar ratio of hydroxyl group to isocyanate group of 1:1; wherein the molecular weight of the hydroxy silicone oil is 500-1000.

5. The process for preparing a high-strength steel pipe based on hot-dip galvanizing according to claim 1, characterized in that: In S22, the amount of the terminal isocyanate silicone oil added is 10-15% of the weight of the epoxy resin.

6. The process for preparing a high-strength steel pipe based on hot-dip galvanizing according to claim 1, characterized in that: In S31, the content of each component in the composite coating, by weight percentage, is 12~18% epoxy-modified acrylic resin and 82~88% silicone oil-modified epoxy resin.

7. The process for preparing a high-strength steel pipe based on hot-dip galvanizing according to claim 1, characterized in that: In S41, the alkaline washing solution is a sodium hydroxide solution with a concentration of 80~100g / L; the pickling solution is a hydrochloric acid solution with a concentration of 60~120g / L; the content of ammonium chloride in the plating solution is 280~300g / L, the content of zinc chloride is 280~320g / L, and the balance is water; the content of each component in the galvanizing solution, by weight percentage, is 0.1~0.5% aluminum, 0.3~0.5% magnesium, 0.005~0.01% steel, 0.1~0.3% lanthanum, 0.02~0.1% silicon, and the balance is zinc.

8. The process for preparing a high-strength steel pipe based on hot-dip galvanizing according to claim 1, characterized in that: In S42, the passivating agent is cured on the metal surface to form a coating with a thickness of 200 to 500 μm.

9. A high-strength steel pipe prepared by a preparation process of a high-strength steel pipe based on hot-dip galvanizing according to any one of claims 1 to 8.

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