Mining anchor rod differential long-acting corrosion prevention method based on function division

Abstract

The invention relates to the technical field of supporting equipment treatment, and discloses a mining anchor rod differential long-acting corrosion prevention method based on function division. The anchor rod is subjected to oil and rust removal and sand blasting treatment; the threaded section is coated with water-based zinc-aluminum coating liquid and pre-dried, and a coating liquid binder base material is formed by compounding silane hydrolysate and titanate; a pipe body is preheated and then subjected to partitioned powder spraying, zinc-containing powder coating is sprayed to a transition area of a free section to form a flexible buffer layer, wear-resistant powder coating is sprayed to a main body area of the free section to form a wear-resistant protective layer, and the powder coating takes dimer acid modified epoxy resin as a matrix. Wherein the wear-resistant powder coating comprises modified nano silicon carbide and glass flakes; and finally performing high-temperature curing to form the film. The anti-cracking performance of the transition area is matched with the wear resistance of the main body area, the corrosion resistance and the anti-sticking capacity of the threaded section are improved, and the anti-cracking anti-sticking threaded rod is suitable for long-term protection under complex underground working conditions.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of supporting equipment processing, in particular to a differential long-acting corrosion prevention method for mine anchor rods based on functional zoning. BACKGROUND

[0002] As a key component of the supporting system of coal mine roadway and underground engineering, the mine anchor rod is in a harsh environment of moisture, water and acid-alkali corrosion medium for a long time, and also needs to bear tensile, bending and shear stress caused by the deformation of surrounding rock. The corrosion of metal matrix and stress fatigue are the main reasons for the failure of the anchor rod, so effective surface corrosion prevention treatment of the anchor rod is an important measure to ensure the safety of underground support.

[0003] The corrosion prevention treatment of the mine anchor rod mainly adopts electrostatic spraying of epoxy powder or hot-dip galvanizing process. In actual application, the service conditions of different parts of the anchor rod are significantly different. The main body of the anchor rod mainly contacts and rubs with the rock hole wall during installation and use, so the anti-wear and anti-scratch performance is required to be high; the transition area of the anchor rod close to the connector or weld is a stress concentration part, which needs to bear large bending moment and alternating load when the surrounding rock deforms, so the flexibility and anti-cracking performance of the coating are required to be high. The existing corrosion prevention process usually uses a single formula of coating material for the whole anchor rod, which is difficult to meet the above differentiated performance requirements. If a high-hardness wear-resistant coating is used, brittle cracking is easy to occur in the transition area due to insufficient toughness, which causes the corrosion medium to penetrate into the matrix; if a high-toughness corrosion prevention coating is used, the main body area is easy to be worn and peeled off by the rock due to insufficient hardness, resulting in local protection failure.

[0004] The protection of the anchor rod thread segment is also a weak link of the existing technology. Due to the requirement of thread matching accuracy, the thread segment is not suitable for using a powder coating or a hot-dip galvanizing layer with large thickness, otherwise it will cause difficulty in nut rotation. The traditional treatment method mostly uses brushing ordinary anti-rust grease or thin-layer organic coating, but such materials are easy to carbonize or decompose in the high-temperature and high-pressure environment during the high-torque installation of the anchor rod, which causes high-temperature bonding between the thread pairs, seriously affecting the subsequent secondary tensioning or disassembly and recovery operations. SUMMARY

[0005] In view of the shortcomings of the prior art, the present application provides a differential long-acting corrosion prevention method for mine anchor rods based on functional zoning, which solves the problem that the single coating of the whole pipe body of the existing mine anchor rod cannot balance the performance contradiction between the anti-bending cracking of the transition area and the wear resistance of the main body area, and the corrosion and sticking failure of the threaded connection part under the high-temperature and high-pressure conditions in the mine.

[0006] To achieve the above purpose, the present application realizes the following technical scheme: a differential long-acting corrosion prevention method for mine anchor rods based on functional zoning, comprising the following steps: S1, surface treatment: oil removal, rust removal and sand blasting roughening treatment are performed on the anchor rod; S2, thread segment corrosion protection: water-based zinc-aluminum coating liquid is coated on the anchor rod thread segment and pre-dried to form a corrosion protection primer; the binder base of the water-based zinc-aluminum coating liquid is compounded from silane hydrolysis liquid and titanate; S3, pipe body preheating: the anchor rod pipe body is heated to a set temperature; S4, zoned powder spraying: zinc-containing powder coating containing dimer acid modified epoxy resin and zinc powder is sprayed on the transition zone of the free section of the anchor rod to form a flexible buffer layer, and then wear-resistant powder coating containing dimer acid modified epoxy resin, modified nano silicon carbide and glass flake is sprayed on the main body zone of the free section of the anchor rod to form a wear-resistant protective layer; S5, curing: the sprayed anchor rod is cured at high temperature to form a differentiated long-acting corrosion protection coating.

[0007] By adopting the above technical scheme, the following beneficial effects can be achieved: The application constructs a differentiated protection system according to the stress characteristics of different parts of the anchor rod. For the stress concentration characteristics of the transition zone of the anchor rod, dimer acid modified epoxy resin is used as the film-forming material, the long-chain aliphatic structure in the dimer acid molecule is introduced into the rigid backbone of the epoxy resin, the flexibility and free volume of the molecular chain segment are increased, the cross-linked network after curing has local microscopic deformation ability, so as to dissipate stress energy through chain segment motion when subjected to bending or impact load, and prevent brittle cracking of the coating. For the characteristics of severe wear in the main body zone of the anchor rod, high-hardness nano silicon carbide and flaky glass flake are introduced into the modified resin matrix to construct an organic-inorganic composite network, and the high modulus characteristics of the inorganic filler are used to bear the friction load.

[0008] The silane and titanate in the water-based zinc-aluminum coating liquid undergo condensation reaction under high temperature environment to generate in-situ high-temperature-resistant inorganic silicon-oxygen-titanium (Si-O-Ti) skeleton structure. Compared with the carbon-carbon bond of conventional organic resin, the inorganic skeleton has higher bond energy and is not easy to decompose or carbonize and bond in the high-temperature environment of the well, and at the same time, the skeleton can firmly anchor the zinc-aluminum powder on the thread surface to provide continuous sacrificial anode protection.

[0009] Preferably, the dimer acid modified epoxy resin in step S4 is a low-toughness modified epoxy resin base or a high-toughness modified epoxy resin base; the low-toughness modified epoxy resin base is prepared by reaction of raw materials containing the following weight parts: bisphenol A type liquid epoxy resin 100 parts, dimer acid 25-35 parts, catalyst 0.1-0.2 parts; the high-toughness modified epoxy resin base is prepared by reaction of raw materials containing the following weight parts: bisphenol A type liquid epoxy resin 100 parts, dimer acid 40-50 parts, catalyst 0.2-0.3 parts.

[0010] By adopting the technical scheme, the density of the flexible chain segment in the molecular chain is accurately controlled by regulating the molar ratio of the dimer acid and the epoxy resin. The flexible chain segment accounts for a high proportion in the high-toughness modified base material, which reduces the elastic modulus of the cured product and is suitable for the transition zone with large deformation; the low-toughness modified base material retains a higher crosslinking density and glass transition temperature and is suitable for the main body zone with higher requirements for anti-permeability and hardness, so that the matching between the performance of the coating material and the working condition requirement is realized.

[0011] Preferably, the preparation method of the dimer acid modified epoxy resin comprises the following steps: under the protection of nitrogen, a bisphenol A type liquid epoxy resin is mixed with dimer acid and heated to 80-90℃, a catalyst is added, and the temperature is continuously raised to 140-155℃ for constant temperature reaction until the acid value is reduced to below 0.5 mgKOH / g, and then volatiles are removed by reduced pressure distillation to obtain the product.

[0012] By adopting the technical scheme, the reaction temperature and the terminal acid value are controlled to promote the selective esterification reaction between the carboxyl group of the dimer acid and the epoxy group of the epoxy resin. The acid value is controlled to be below 0.5 mgKOH / g, which indicates that the carboxyl group has been completely converted, avoids the adverse effect of residual free acid on the water resistance of the coating, and at the same time ensures that the modified resin molecule retains enough epoxy groups at the end, so as to be subsequently crosslinked and cured with a curing agent.

[0013] Preferably, the water-based zinc-aluminum coating liquid in step S2 comprises the following components in mass percentage: 25.0%-35.0% of flaky zinc powder, 5.0%-8.0% of flaky aluminum powder, 15.0%-20.0% of binder base material, 35.0%-36.3% of deionized water, and the balance of additives and solvents; wherein the binder base material is compounded by γ-glycidoxypropyltrimethoxysilane hydrolysate and isopropyl tri (dioctyl pyrophosphate) titanate at a mass ratio of 2-4:1.

[0014] By adopting the technical scheme, the introduction of titanate improves the wetting and dispersibility of the flaky metal pigment in the aqueous phase and prevents agglomeration. In the film forming process, the titanate acts as a catalyst to promote the dehydration condensation of the silanol group, the hydrolysis product of silane, to accelerate the formation of inorganic network and improve the density of the coating. The flaky zinc powder and aluminum powder are stacked and arranged in the coating to form a physical shielding layer to block the contact of the corrosion medium with the substrate.

[0015] Preferably, the zinc-containing powder coating in step S4 is prepared from the following raw materials by weight: 50-60 parts of bisphenol A type solid epoxy resin, 10-15 parts of dimer acid modified epoxy resin, 3-4 parts of curing agent, 0.1-0.2 parts of accelerator, 0.8-1.0 parts of leveling agent, 0.4-0.6 parts of degassing agent, 15-20 parts of zinc powder, and 4-11 parts of filler; wherein the dimer acid modified epoxy resin is selected from the low-toughness modified epoxy resin base or the high-toughness modified epoxy resin base.

[0016] By adopting the above technical solution, the dimer acid modified resin is blended and cured with the bisphenol A type solid epoxy resin to form an interpenetrating network structure with a toughness domain. The zinc powder is uniformly dispersed in the network. When the corrosion medium penetrates into the coating, the zinc powder preferentially undergoes oxidation reaction, and the generated corrosion products expand in volume to fill the micro-pores of the coating, block the corrosion channel, and delay the corrosion of the substrate.

[0017] Preferably, the wear-resistant powder coating in step S4 is prepared from the following raw materials by weight: 45-50 parts of bisphenol A type solid epoxy resin, 18-22 parts of dimer acid modified epoxy resin, 27-28 parts of curing agent, 0.1-0.2 parts of accelerator, 0.8-1.0 parts of leveling agent, 0.4-0.6 parts of degassing agent, 3-5 parts of modified nanometer silicon carbide, and 20-30 parts of glass flake; wherein the dimer acid modified epoxy resin is selected from the low-toughness modified epoxy resin base or the high-toughness modified epoxy resin base.

[0018] By adopting the above technical solution, the synergistic effect of fillers of different scales is utilized to enhance the coating. The micron-sized flaky glass flake is arranged parallel to the surface of the substrate in the coating, greatly increasing the penetration path length of the corrosion medium; the nanometer-sized silicon carbide particles are dispersed and filled in the interstitial gaps between the resin macromolecular segments, limiting the relative slipping of the segments, and resisting external abrasive cutting by utilizing its extremely high hardness, thereby improving the overall wear resistance and permeation resistance of the coating.

[0019] Preferably, in the preparation process of the wear-resistant powder coating, the modified nanometer silicon carbide is prepared by dispersing nanometer silicon carbide in a mixed solution of alcohol solvent and γ-aminopropyl triethoxysilane, and then subjecting to ultrasonic dispersion and drying treatment; and in the melt extrusion step, the components except for the glass flake and the modified nanometer silicon carbide are mixed first, then the glass flake is added and mixed at low speed, and then extruded.

[0020] By adopting the above technical solution, the silane coupling agent is grafted onto the surface of the nanometer silicon carbide, converting the originally hydrophilic inorganic surface into a lipophilic surface, enhancing the interfacial bonding force between the filler and the epoxy resin matrix, and eliminating the interfacial micro-cracks. The step-by-step mixing process prevents the damage of high shear force to the brittle glass flake, retains the large diameter-thickness ratio characteristics of the glass flake, and ensures that the glass flake can form an effective flake shielding structure in the coating.

[0021] Preferably, the pipe body preheating temperature in step S3 is 200-240 DEG C; in step S4, the coating thickness of the transition zone is controlled to be 150-250 mu m, and the coating thickness of the main body zone is controlled to be 300-500 mu m; the transition zone is a zone 0-500 mm away from the joint weld.

[0022] By adopting the technical scheme, the powder coating is rapidly melted and leveled in the instant of contact by using the substrate waste heat, the melt viscosity is reduced, the wetting and filling of the coating to the micro-pores on the substrate surface are promoted, and the physical anchoring effect is enhanced.

[0023] Preferably, the curing process in step S5 is constant temperature curing at 180-220 DEG C for 15-30 minutes, and after curing, air cooling or water mist quenching is adopted to cool to room temperature.

[0024] The application provides a mine anchor rod differential long-acting corrosion prevention method based on functional zoning. 1、The application solves the contradiction that a single coating formula is difficult to balance between high wear resistance and high toughness by constructing a differential protective coating in different stress regions of the anchor rod.

[0025] 2、The application uses a silane hydrolysis liquid and a titanate to be compounded as a binder of the water-based zinc-aluminum coating liquid.

[0026] 3、The present application improves the micro-interface bonding force and compactness of the coating through surface modification of the filler and optimization of the mixing process. The surface of nano-silicon carbide is treated by surface grafting with a silane coupling agent, which improves the interface compatibility between the inorganic filler and the organic epoxy resin matrix, and reduces the micro-pore defects caused by poor interface bonding. In combination with the low-speed mixing process for glass flake, the large diameter-thickness ratio characteristics of the flake are retained, so that a parallel arrangement of physical barrier network is formed in the coating, effectively prolonging the diffusion path of the corrosion medium to the matrix, and synergistically improving the impact strength and chemical corrosion resistance of the coating. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 The method flowchart of the present application; Figure 2 The anchor rod function partition and coating distribution schematic diagram of the present application. DETAILED DESCRIPTION

[0028] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the specification of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0029] Please refer to the drawings in the specification of the present application Figure 1 - the drawings in the specification of the present application Figure 2 The embodiments of the present application provide a mine anchor rod differential long-acting corrosion prevention method based on function partition.

[0030] The sources and specifications of the main raw materials and reagents used in the following examples and comparative examples are as follows. The reagents not specifically described are commercially available analytical pure or higher grade products.

[0031] Bisphenol A type solid epoxy resin (E-12), epoxy equivalent weight 750-850 g / eq; Bisphenol A type liquid epoxy resin (E-51), epoxy equivalent weight 184-195 g / eq; Dimer acid, dimer content ≥95%, acid value 190-198 mgKOH / g; Phenolic curing agent, hydroxyl equivalent weight 250-300 g / eq; Dicyandiamide, CAS number: 461-58-5, purity ≥99.5%; 2-Methylimidazole, purity ≥99.0%; Triphenylphosphine, CAS number: 603-35-0, purity ≥99.0%; Benzoic acid, purity ≥99.0%; Barium sulfate, CAS No. 7727-43-7, average particle size 0.7-1.0 μm.

[0032] Flaky zinc powder, average flake size 10-15 μm, metal zinc content ≥ 90%; Spherical zinc powder, CAS No. 7440-66-6, average particle size D50 3-5 μm, metal zinc content ≥ 99%; Flaky aluminum powder, CAS No. 7429-90-5, average flake size 10-15 μm, non-floated type; Nano-silicon carbide, CAS No. 409-21-2, β crystal form, average particle size 40-60 nm; Glass flake, particle size distribution 100-300 mesh, treated with coupling agent.

[0033] γ-glycidoxypropyltrimethoxysilane (KH-560); γ-aminopropyltriethoxysilane (KH-550), CAS No. 919-30-2; Isopropyl tri(dioctyl phosphato) titanate, CAS No. 65345-34-8; Ethylene glycol monobutyl ether, CAS No. 111-76-2; Hydroxyethyl cellulose, CAS No. 9004-62-0; Polyether-modified polysiloxane, CAS No. 134180-76-0; Polybutyl acrylate leveling agent, CAS No. 9003-49-0.

[0034] Preparation Example 1: This preparation example provides a low-toughness modified epoxy resin base, comprising the following steps: Into a four-necked flask with mechanical stirring, condenser and thermometer, 100 parts by weight of bisphenol A type liquid epoxy resin (E-51) and 30 parts by weight of dimer acid were added, and nitrogen was introduced for protection; the temperature was raised to 85°C, and 0.15 parts by weight of catalyst triphenylphosphine was added; the temperature was continuously raised to 145°C, and the reaction was kept constant for 3.5 hours, during which the acid value was measured every 30 minutes; when the acid value was reduced to below 0.5 mgKOH / g, the reaction was stopped; the bubbles and volatile matter were removed by distillation under reduced pressure, and the product was discharged after cooling, to obtain a low-toughness modified epoxy resin base (the theoretical epoxy equivalent weight was about 310 g / eq).

[0035] Preparation Example 2: This preparation example provides a high-toughness modified epoxy resin base, comprising the following steps: Into a four-necked flask with mechanical stirring, condenser and thermometer, 100 parts by weight of liquid bisphenol A type epoxy resin (E-51) and 45 parts by weight of dimer acid were added, and nitrogen was introduced; the temperature was raised to 90°C, 0.25 parts by weight of catalyst triphenylphosphine was added; the temperature was continuously raised to 150°C, and the reaction was kept for 4.5 hours, during which the acid value was determined every 30 minutes; when the acid value was reduced to below 0.5 mgKOH / g, the reaction was stopped; the bubbles and volatile matters were removed by distillation under reduced pressure, and the product was discharged after cooling, to obtain a high-toughness modified epoxy resin base (the theoretical epoxy equivalent weight was about 400 g / eq).

[0036] Preparation Example 3: The present preparation example provides a zinc-containing powder coating for free section transition zone, the components of which include, by weight parts: Epoxy resin (E-12) 60 parts, low-toughness modified epoxy resin base prepared in Preparation Example 1 10 parts, dicyandiamide 3 parts, 2-methylimidazole 0.1 part, polybutyl acrylate leveling agent 0.8 part, benzoin 0.4 part, spherical zinc powder 15 parts, and precipitated barium sulfate 10.7 parts.

[0037] The preparation method includes: pre-mixing the above materials in a high-speed mixer for 5 minutes, melt-extruding through a twin-screw extruder, setting the extrusion temperature section to 90°C / 100°C / 100°C, and obtaining the zinc-containing powder coating by tabletting, cooling, crushing, and passing through a 180-mesh sieve.

[0038] Preparation Example 4: The present preparation example provides a zinc-containing powder coating (gradient repair powder) for free section transition zone, the components of which include, by weight parts: Epoxy resin (E-12) 55 parts, high-toughness modified epoxy resin base prepared in Preparation Example 2 15 parts, dicyandiamide 3.5 parts, 2-methylimidazole 0.2 part, polybutyl acrylate leveling agent 1.0 part, benzoin 0.6 part, spherical zinc powder 20 parts, and precipitated barium sulfate 4.2 parts.

[0039] The preparation method is the same as that in Preparation Example 3.

[0040] Preparation Example 5: The present preparation example provides a wear-resistant powder coating (main protection powder) for free section main body, the components of which include, by weight parts: Epoxy resin (E-12) 50 parts, low-toughness modified epoxy resin base prepared in Preparation Example 1 18 parts, phenolic curing agent 28 parts, 2-methylimidazole 0.1 part, polybutyl acrylate leveling agent 0.8 part, benzoin 0.4 part, nano-silicon carbide 3 parts, and glass flake 20 parts.

[0041] The preparation method comprises the following steps: dispersing the nanometer silicon carbide in a mixed solution of ethanol and KH-550 silane (mass ratio 1:10), ultrasonic dispersion for 45 minutes, drying at 80 DEG C to remove the solvent and dispersing to obtain the modified nanometer ceramic filler; pre-mixing all components except the glass flake and the modified nanometer ceramic filler in a high-speed mixer, uniformly mixing the glass flake at low speed, melting and extruding through a double-screw extruder, controlling the screw speed to reduce the glass flake breaking, setting the extrusion temperature section to 90 DEG C / 100 DEG C / 100 DEG C, and obtaining the wear-resistant powder coating through tabletting, cooling, crushing and screening through a 180-mesh screen.

[0042] Preparation Example 6: The preparation example provides a wear-resistant powder coating for a free section main body, and components thereof include, by weight parts: epoxy resin (E-12) 45 parts, high-toughness modified epoxy resin base material prepared in preparation example 2 22 parts, phenolic curing agent 27 parts, 2-methyl imidazole 0.2 parts, polybutyl acrylate leveling agent 1.0 part, benzoin 0.6 part, nanometer silicon carbide 5 parts, and glass flake 30 parts.

[0043] The preparation method is the same as that in preparation example 5.

[0044] Preparation Example 7: The preparation example provides a water-based zinc-aluminum coating liquid for a threaded section, and components thereof include, by mass percentage: flaky zinc powder 25.0%, flaky aluminum powder 8.0%, binder base material 20.0%, deionized water 36.3%, ethylene glycol monobutyl ether 9.0%, hydroxyethyl cellulose 1.5%, and polyether modified polysiloxane 0.2%. The binder base material is compounded by KH-560 silane hydrolysis solution and isopropyl tri (dioctyl diphosphate) titanate at a mass ratio of 3:1, and the silane hydrolysis solution is prepared by pre-hydrolyzing for 2 hours with ice acetic acid to adjust the pH to 4.0.

[0045] The preparation method comprises the following steps: mixing and stirring the deionized water, ethylene glycol monobutyl ether, binder base material, hydroxyethyl cellulose and polyether modified polysiloxane uniformly, slowly adding the flaky zinc powder and flaky aluminum powder, and dispersing for 45 minutes at a speed of 500 rpm to control the coating liquid viscosity to be 40 s (4 cups, 25 DEG C).

[0046] Preparation Example 8: The preparation example provides a water-based zinc-aluminum coating liquid for a threaded section, and components thereof include, by mass percentage: flaky zinc powder 35.0%, flaky aluminum powder 5.0%, binder base material 15.0%, deionized water 35.0%, ethylene glycol monobutyl ether 8.7%, hydroxyethyl cellulose 0.8%, and polyether modified polysiloxane 0.5%.

[0047] The binder base material is compounded in the same way as in preparation example 7.

[0048] The preparation method comprises the following steps: mixing and stirring deionized water, ethylene glycol monobutyl ether, a binder base, hydroxyethyl cellulose and polyether modified polysiloxane uniformly, slowly adding flaky zinc powder and flaky aluminum powder, and dispersing at 800 rpm for 30 minutes to control the coating liquid viscosity to be 60 s (4-cup coating, 25 DEG C.).

[0049] Example 1 The embodiment provides a preparation process of a multifunctional protective coating for an anchor rod, and comprises the following steps. Surface treatment: the anchor rod is subjected to oil removal and rust removal treatment, the anchor rod surface roughness Ra reaches 40 mu m through a sand blasting process, and a Sa2.5 grade rust removal standard is reached; Thread coating: the water-based zinc-aluminum coating liquid prepared in the preparation example 7 is sprayed on the anchor rod thread segment, pre-drying is carried out at 80 DEG C. for 15 minutes, and a corrosion-resistant bottom layer is formed; Preheating: the anchor rod pipe body subjected to surface treatment is inductively heated to 200 DEG C. (workpiece surface temperature); Powder spraying: an electrostatic spraying gun is used, and the voltage is set to 60 kV. First, the zinc-containing powder coating (gradient repair powder) prepared in the preparation example 3 is sprayed on the transition zone (0-500 mm area from the joint weld) of the anchor rod free section, and the coating thickness is controlled to be 150 mu m; then, the wear-resistant powder coating (main body protective powder) prepared in the preparation example 5 is sprayed on the main body zone (the remaining pipe body part) of the anchor rod free section, and the coating thickness is controlled to be 300 mu m; Curing: the anchor rod after spraying is sent into a curing furnace, constant temperature curing is carried out at 180 DEG C. for 30 minutes, after curing is completed, air cooling is carried out to room temperature, and a finished anchor rod is obtained.

[0050] Example 2 The embodiment provides a preparation process of a multifunctional protective coating for an anchor rod, and comprises the following steps. Surface treatment: the anchor rod is subjected to oil removal and rust removal treatment, the anchor rod surface roughness Ra reaches 50 mu m through a sand blasting process, and a Sa2.5 grade rust removal standard is reached; Thread coating: the water-based zinc-aluminum coating liquid prepared in the preparation example 7 is immersed and coated on the anchor rod thread segment, pre-drying is carried out at 100 DEG C. for 10 minutes, and a corrosion-resistant bottom layer is formed; Preheating: the anchor rod pipe body subjected to surface treatment is inductively heated to 220 DEG C. (workpiece surface temperature); Powder spraying: an electrostatic spraying gun is used, and the voltage is set to 70 kV. First, the zinc-containing powder coating prepared in the preparation example 3 is sprayed on the transition zone (0-500 mm area from the joint weld) of the anchor rod free section, and the coating thickness is controlled to be 200 mu m; then, the wear-resistant powder coating (main body protective powder) prepared in the preparation example 6 is sprayed on the main body zone (the remaining pipe body part) of the anchor rod free section, and the coating thickness is controlled to be 400 mu m; Curing: the sprayed anchor rod is sent into a curing oven, and is cured at 200℃ for 20 minutes. After curing, the anchor rod is air-cooled to room temperature to obtain a finished anchor rod.

[0051] Example 3 The present embodiment provides a preparation process of a multifunctional protective coating for an anchor rod, comprising the following steps: Surface treatment: the anchor rod is subjected to oil removal and rust removal treatment, and the surface roughness Ra of the anchor rod is made to reach 60 μm through sand blasting process to reach Sa3.0 grade rust removal standard; Thread coating: the water-based zinc-aluminum coating solution prepared in Preparation Example 8 is brushed on the threaded segment of the anchor rod, and is pre-dried at 120℃ for 5 minutes to form an anti-corrosion primer; Preheating: the surface-treated anchor rod pipe body is inductively heated to 240℃ (workpiece surface temperature); Powder spraying: an electrostatic spraying gun is used, and the voltage is set to 80 kV. First, the zinc-containing powder coating (gradient repair powder) prepared in Preparation Example 4 is sprayed on the transition zone (0-500 mm area from the joint weld) of the free section of the anchor rod, and the coating thickness is controlled to be 250 μm; then, the wear-resistant powder coating (main body protective powder) prepared in Preparation Example 6 is sprayed on the main body zone (the remaining pipe body part) of the free section of the anchor rod, and the coating thickness is controlled to be 500 μm; Curing: the sprayed anchor rod is sent into a curing oven, and is cured at 220℃ for 15 minutes. After curing, the anchor rod is water mist quenched to room temperature to obtain a finished anchor rod.

[0052] Comparative Example 1 Compared with Example 1, the difference lies in that the modified epoxy resin base in the zinc-containing powder coating and the wear-resistant powder coating used is all replaced with equal mass of ordinary bisphenol A type epoxy resin (E-12), and the amount of curing agent is adjusted accordingly to keep the stoichiometric ratio balanced, and the rest is the same.

[0053] Comparative Example 2 Compared with Example 1, the difference lies in that the zoned coating is cancelled, and the transition zone (0-500 mm area) of the free section of the anchor rod is not sprayed with zinc-containing powder coating, but is uniformly sprayed with the wear-resistant powder coating prepared in Preparation Example 5 as the main body zone, and the coating thickness of the whole pipe body is controlled to be 300 μm, and the rest is the same.

[0054] Comparative Example 3 Compared with Example 1, the difference lies in that in the preparation process of the wear-resistant powder coating used, nano silicon carbide and glass flake are not added, but equal mass of precipitated barium sulfate is used instead, and the rest is the same.

[0055] Comparative Example 4 Compared with Example 1, the difference is that in the preparation process of the wear-resistant powder coating used, the nano silicon carbide was not modified by the mixture of ethanol and KH-550 silane, but was directly added to a high-speed mixer for physical mixing. All other aspects are the same.

[0056] Comparative Example 5: Compared with Example 1, the difference is that in the water-based zinc-aluminum coating liquid used, the binder base material is no longer composed of KH-560 silane hydrolysate and titanate, but is replaced by an equal mass of commercially available water-based acrylic emulsion, while the rest are the same.

[0057] Test Example 1 Experimental instructions This test case mainly examines the physical and mechanical properties and corrosion resistance of the anchor bolt protective coatings prepared in Examples 1-3 and Comparative Examples 1-5. The test samples were prepared as follows: 4135 alloy steel plates (150mm × 70mm × 5mm) and short anchor bolts of the same material as the anchor bolts were used as substrates. Test samples were prepared according to the surface treatment, coating, and curing processes corresponding to each example and comparative example.

[0058] The specific test items and standards are as follows: Coating thickness: A magnetic thickness gauge was used to measure the thickness at 5 points along the diagonal of the sample and the average value was taken.

[0059] Adhesion: The bonding strength between the coating and the substrate was determined using an automatic pull-off tester.

[0060] Impact resistance: The maximum impact energy when the coating cracks or peels is recorded using a heavy hammer impact tester.

[0061] Abrasion resistance: Using a Taber abrasion tester, a CS-17 grinding wheel, a load of 1000g, and a rotation of 500 revolutions, the weight loss of the coating was recorded.

[0062] Bending resistance of the transition zone: A self-designed experiment was conducted based on the stress characteristics of the transition zone of the anchor bolt. A 300mm long section of pipe containing the transition zone coating was cut and subjected to three-point bending loading on a universal testing machine. When the displacement of the indenter reached 10mm, the coating in the transition zone was observed for micro-cracks (observed using a 10x magnifying glass).

[0063] High-temperature anti-sticking property of threads: The male and female connectors coated with thread coating are threaded, heated to 180℃ and kept at that temperature for 24 hours. After cooling, they are disassembled, the disassembly torque is recorded and the coating peeling is observed.

[0064] Salt spray corrosion resistance: Neutral salt spray test, test cycle 1000 hours, corrosion spread width on one side at the cross mark.

[0065] The experimental data are shown in Table 1; Table 1 Performance test results of anchor rod multifunctional protective coating

[0066] Summary: The data of Examples 1 to 3 show that the adhesion, impact resistance and wear resistance values of the coating prepared by using dimer acid modified epoxy resin and zoned coating process are at a relatively high level. The performance of Example 2 is relatively more optimal, which is related to the higher curing temperature promoting the densification of the crosslinked network.

[0067] Comparing Example 1 with Comparative Example 1, the impact resistance of Comparative Example 1 decreases from 12.5 J to 4.5 J after replacing the dimer acid modified resin with ordinary epoxy resin, and cracking occurs in the transition zone bending test. The long carbon chain structure of dimer acid introduces into the main chain of epoxy resin, increasing the flexibility and free volume of the molecular chain segment, and giving the cured network the ability to deform. Comparative Example 1 lacks this flexible segment, resulting in a brittle coating that is difficult to adapt to external deformation.

[0068] Comparing Example 1 with Comparative Example 2, Comparative Example 2 cancels the zoned coating, and micro-cracks are observed in the transition zone bending test. The zinc-containing powder coating used in the transition zone of the example has a lower modulus, acting as a buffer layer to release the stress generated by the substrate deformation. In Comparative Example 2, the high-hardness wear-resistant coating is used throughout the entire pipe system, and the transition zone coating cannot dissipate stress concentration through its own deformation.

[0069] Comparing Example 1 with Comparative Examples 3 and 4, Comparative Example 3 does not add wear-resistant fillers, with a wear loss of 85.7 mg; Comparative Example 4 adds unmodified fillers, with a wear loss of 42.6 mg, and the adhesion decreases to 14.8 MPa. The unmodified nano-silicon carbide has high surface energy and is prone to agglomeration, causing internal defects in the coating. After grafting modification by silane coupling agent, the fillers form an organic-inorganic network with the resin matrix through chemical bonds, improving the dispersion of the fillers and the interfacial bonding strength, thereby bearing the friction load and blocking corrosive media.

[0070] Comparing Example 1 with Comparative Example 5, Comparative Example 5 uses an acrylic emulsion as the thread coating adhesive, and the high-temperature disassembly torque increases to 580 N·m, and sticking occurs. Ordinary organic resins soften or thermally degrade at 180℃, losing their isolation effect. The organosilicon-titanate system used in this scheme forms an inorganic silicon-oxygen skeleton through condensation reaction at high temperature, maintaining the anti-sticking performance in high temperature environment Test Example 2 Experimental description; This test example mainly investigates the chemical stability and anti-permeation performance of the coating in high temperature and high pressure (HTHP) environment. Coating samples prepared from Examples 1-3 and Comparative Examples 1-4 (substrate is 4135 steel) are tested as follows: High temperature and high pressure autoclave corrosion test was conducted according to NACE TM0185 standard. The test panel was placed in a Hastelloy autoclave, the test medium was simulated formation water, CO2 was introduced into the gas phase space until the partial pressure reached 2 MPa, the total pressure was maintained at 20 MPa, the test temperature was set to 150°C, and the test period was 168 hours.

[0071] After the test, the panel was taken out and naturally cooled at room temperature, and then cleaned and dried. The coating surface blistering grade was evaluated according to ASTM D714 standard (10 grade for no blistering, 8 grade and below for different degrees of blistering).

[0072] The adhesion test (pull-off method) was conducted again on the panel after autoclave test, and the residual adhesion after high temperature and high pressure aging was recorded.

[0073] Electrochemical impedance spectroscopy (EIS) test was conducted on the panel before and after autoclave test using an electrochemical workstation. A three-electrode system was used, with the coating panel as the working electrode, platinum as the counter electrode, saturated calomel electrode (SCE) as the reference electrode, and 3.5% NaCl solution as the electrolyte solution. The test frequency range was 10 5 Hz-10 2 Hz, the sine wave perturbation amplitude was 10 mV, and the impedance modulus at the low frequency end (0.01 Hz) was recorded .

[0074] The experimental data are shown in Table 2; Table 2 High temperature and high pressure (HTHP) test and electrochemical impedance test results of the coating

[0075] Summary; After experiencing high temperature and high pressure CO2 and brine immersion, the surface of Examples 1 to 3 had no blistering phenomenon, and the low frequency impedance modulus was maintained at the level of 10 9 Ω cm2. The impedance retention rate of Example 2 was the highest (49.8%), indicating that higher curing temperature improved the crosslinking density of the resin matrix, and the dense three-dimensional network structure reduced the diffusion coefficient of water molecules and ions.

[0076] Comparing Example 1 with Comparative Example 3, the autoclave impedance modulus of Comparative Example 3, which did not add nano silicon carbide and glass flake, decreased to the level of 10 5 , the impedance retention rate was only 0.07%, the surface appeared moderate blistering, and the adhesion decreased to 4.2 MPa. Lack of barrier of flaky glass flake and particulate filler, the corrosion medium penetrated to the substrate interface along the pores of the resin matrix, resulting in interface reaction and coating peeling. The compounded filler in the example prolonged the diffusion path of the medium and improved the permeation resistance of the coating.

[0077] Comparative Example 1 and Comparative Example 4, Comparative Example 4 uses unmodified filler, the impedance retention rate after the kettle is 1.27%, and dense micro-bubbles appear. The unmodified inorganic filler has poor interface compatibility with the organic resin matrix, and there are micro voids. Under high temperature and high pressure conditions, water molecules are easy to penetrate along the surface of the hydrophilic filler. The surface of the filler is modified by silane coupling agent in the scheme, which eliminates the interface void, enhances the chemical bonding of the filler and the matrix, limits the aggregation of water molecules at the interface, and maintains a high impedance value and adhesion.

[0078] Comparative Example 1 and Comparative Example 1, Comparative Example 1 uses ordinary epoxy resin, a small amount of blister appears after the kettle, and the impedance retention rate is low (16.5%). The ordinary epoxy resin has a large internal stress, and is easy to produce micro-cracks in the swelling-shrinking process under high temperature and high pressure. The dimer acid modified epoxy resin has good flexibility and can adapt to the volume change under high temperature and high pressure environment, and maintain the integrity of the coating structure.

Claims

1. A method for differentiating long-acting corrosion protection of mine anchor based on functional zoning, characterized in that, The method comprises the following steps: S1, surface treatment: sand blasting and rust removal are performed on the mine anchor rod, so that the surface roughness Ra reaches 40-60 μm, and the rust removal level reaches Sa2.5-Sa3.0 level; S2, corrosion protection treatment of the threaded section: a water-based zinc-aluminum coating solution is coated on the threaded section of the anchor rod, and a corrosion protection primer is formed after pre-drying; the water-based zinc-aluminum coating solution is made of raw materials containing the following mass percentages: flaky zinc powder 25.0%-35.0%, flaky aluminum powder 5.0%-8.0%, binder base 15.0%-20.0%, deionized water 35.0%-36.3%, ethylene glycol monobutyl ether 8.7%-9.0%, hydroxyethyl cellulose 0.8%-1.5%, and polyether-modified polysiloxane 0.2%-0.5%; the binder base is compounded by KH-560 silane hydrolysis solution and isopropyl tri(dioctyl ester) titanate at a mass ratio of 3:1, and is used to form an inorganic silicon-oxygen skeleton at high temperature to maintain the anti-buckle performance; S3, zoned coating of the free section: the free section of the anchor rod is divided into a transition zone 0-500 mm away from the threaded end and a main body zone, and electrostatic spraying process is used to spray zinc-containing powder coating and wear-resistant powder coating in sequence, wherein the coating thickness of the transition zone is 150-250 μm, and the coating thickness of the main body zone is 300-500 μm; S4, curing treatment: the coated anchor rod is placed in a curing furnace for constant temperature curing at 180-220 ℃ for 15-30 minutes, and the mine anchor rod is obtained after cooling.

2. The method according to claim 1, characterized in that, The dimer acid modified epoxy resin in the step S4 is a low-toughness modified epoxy resin base or a high-toughness modified epoxy resin base; The low-toughness modified epoxy resin base is prepared by reaction of raw materials containing the following amounts by weight: bisphenol A type liquid epoxy resin 100 parts, dimer acid 25-35 parts, and catalyst 0.1-0.2 parts; The high-toughness modified epoxy resin base is prepared by reaction of raw materials containing the following amounts by weight: bisphenol A type liquid epoxy resin 100 parts, dimer acid 40-50 parts, and catalyst 0.2-0.3 parts; The catalyst is triphenylphosphine.

3. The method according to claim 2, characterized in that, The preparation method of the dimer acid modified epoxy resin comprises: Under nitrogen protection, the bisphenol A type liquid epoxy resin is mixed with the dimer acid and heated to 80-90 ℃, the catalyst is added, and the temperature is continuously raised to 140-155 ℃ for constant temperature reaction until the acid value is reduced to below 0.5 mgKOH / g, and then volatile components are removed by reduced pressure distillation.

4. The method according to claim 1, characterized in that, The water-based zinc-aluminum coating solution in the step S2 contains the following components in the following mass percentages: Flaky zinc powder 25.0%-35.0%, flaky aluminum powder 5.0%-8.0%, binder base 15.0%-20.0%, deionized water 35.0%-36.3%, and the balance of additives and solvents; The additives are ethylene glycol monobutyl ether, hydroxyethyl cellulose, and polyether-modified polysiloxane; The binder base is compounded by γ-glycidyl ether oxypropyl trimethoxysilane hydrolysis solution and isopropyl tri(dioctyl ester) titanate at a mass ratio of 2-4:

1.

5. The method according to claim 1, characterized in that, The zinc-containing powder coating in the step S4 is made of raw materials containing the following amounts by weight: Bisphenol A type solid epoxy resin 50-60 parts, dimer acid modified epoxy resin 10-15 parts, curing agent 3-4 parts, accelerator 0.1-0.2 parts, leveling agent 0.8-1.0 parts, degassing agent 0.4-0.6 parts, zinc powder 15-20 parts, filler 4-11 parts.

6. The method according to claim 5, characterized in that, The preparation method of the zinc-containing powder coating comprises: premixing raw materials, melting and extruding through a double-screw extruder at 90-100 DEG C, tabletting, crushing, sieving, and obtaining.

7. The method according to claim 1, characterized in that, The wear-resistant powder coating in step S4 is made from raw materials comprising the following parts by weight: Bisphenol A type solid epoxy resin 45-50 parts, dimer acid modified epoxy resin 18-22 parts, curing agent 27-28 parts, accelerator 0.1-0.2 parts, leveling agent 0.8-1.0 parts, degassing agent 0.4-0.6 parts, modified nanoscale silicon carbide 3-5 parts, glass flake 20-30 parts.

8. The method according to claim 7, characterized in that, In the preparation process of the wear-resistant powder coating, the modified nanoscale silicon carbide is prepared by dispersing nanoscale silicon carbide in a mixed solution of alcohol solvent and gamma-aminopropyl triethoxysilane, ultrasonic dispersion and drying treatment; And in the melting and extruding step, the components except glass flake and the modified nanoscale silicon carbide are mixed first, then the glass flake is added and mixed at low speed, and then extruded.

9. The method according to claim 1, characterized in that, The pipe body preheating temperature in step S3 is 200-240 DEG C; In step S3, the coating thickness of the transition zone is controlled to be 150-250 microns, and the coating thickness of the main zone is controlled to be 300-500 microns. The transition zone is a zone 0-500 mm away from the joint weld.

10. The method according to claim 1, characterized in that, The curing process in step S4 is constant temperature curing at 180-220 DEG C for 15-30 minutes, and after curing, air cooling or water mist quenching to room temperature is adopted.

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