Environment-friendly corrosion inhibition concentrated solution for hydraulic support and preparation method of environment-friendly corrosion inhibition concentrated solution

Abstract

The invention relates to the technical field of corrosion inhibitors, in particular to an environment-friendly corrosion inhibition concentrated solution for a hydraulic support and a preparation method of the environment-friendly corrosion inhibition concentrated solution. The preparation method comprises the following steps: dissolving chitosan with lactic acid to form an acid sol, and carrying out segmented reaction on the acid sol and a part of neutralized phytic acid solution to obtain a complex graft; meanwhile, preparing an amphiphilic and hydrophobic polydopamine dispersion; mixing the two components, performing alkaline curing, and adding components such as sodium gluconate and trisodium citrate to optimize the system. The obtained concentrated solution can form a compact and hydrophobic organic complexing protective film on the surface of carbon steel after being diluted, the corrosion inhibition performance is remarkably improved through strong adsorption of multiple coordination bonds, and the corrosion inhibitor has the advantages of low foam, hard water resistance, excellent stability and environmental friendliness and is suitable for harsh working conditions of mines.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of corrosion inhibitors, and particularly relates to an environmentally friendly corrosion inhibitor concentrate for hydraulic supports and a preparation method thereof. BACKGROUND

[0002] As a key support device for fully-mechanized coal mining faces, the stability and reliability of the hydraulic system of the hydraulic support are directly related to the safety in production and mining efficiency of the mine. The hydraulic transmission medium generally uses emulsion or concentrate with water as the main component, which is widely used due to its incompressibility, cooling property and economy. However, the inherent characteristics of the water-based medium also bring significant corrosion and wear challenges to the hydraulic support system. In the complex water quality environment of high temperature, high humidity, rich in chloride ions and sulfate ions under the mine, the carbon steel pipeline and cylinder body are prone to electrochemical corrosion, which not only shortens the service life of the equipment, but also exists the safety hidden danger of support instability caused by component corrosion failure.

[0003] In order to pursue high-efficiency corrosion inhibition performance, the traditional corrosion inhibitor technology for hydraulic supports often relies on chromate, nitrite, heavy metal salt or phosphate ester. Although such substances can form passivation films or adsorption films on the metal surface, they have poor environmental friendliness, low biodegradability, environmental pollution risk, and some components are strictly limited by environmental regulations. With the deepening of the concept of green mine construction, the development of environmentally friendly corrosion inhibitors has become an urgent need in the industry.

[0004] Some existing environmentally friendly corrosion inhibitors attempt to use natural polymers or organic acid substances such as phytic acid, chitosan, etc., which have biodegradability and certain metal chelating ability. However, such substances often face problems such as insufficient corrosion inhibition efficiency, poor film densification, poor long-term stability, etc. in actual application. Especially for the working conditions of dynamic operation and shear force flushing of the hydraulic support system, the protective film formed by simple physical adsorption or simple complexation is easy to fall off, and it is difficult to provide persistent and effective protection. In addition, the synergistic mechanism between the components in the existing technical solutions is often not clear enough, resulting in unsatisfactory compounding effect, and it is difficult to build a multi-level protection structure with strong adsorption, high densification, hydrophobic barrier and self-repairing potential on the metal surface.

[0005] The hydraulic support working fluid also needs to have good stability, including hard water resistance, low foam, anti-layering, etc., to ensure that the transmission accuracy is not affected or the pump is not cavitated due to foam, sedimentation, etc. in the circulating system. Some existing environmentally friendly formulations are prone to delamination, precipitation, etc. under complex water quality or temperature changes, affecting their use effect and promotion. Therefore, how to break through the existing technical bottlenecks under the premise of ensuring environmental friendliness and develop a corrosion inhibitor concentrate for hydraulic supports that can adapt to harsh mine working conditions and has comprehensive excellent performance is a technical problem to be solved in the field. SUMMARY

[0006] Therefore, the present application aims to provide an environmentally friendly corrosion inhibitor concentrate for hydraulic support and a preparation method thereof to solve the technical problems of insufficient long-term corrosion inhibition performance of existing environmentally friendly corrosion inhibitors due to single film forming mechanism and poor component synergy, and easy peeling of the film layer and weak anti-mediator penetration ability under dynamic working conditions.

[0007] To achieve the above purpose, the present application provides a preparation method of an environmentally friendly corrosion inhibitor concentrate for hydraulic support, comprising the following steps:

[0008] (1) After adding lactic acid aqueous solution in water and stirring, chitosan is added to obtain chitosan acid sol;

[0009] (2) Partially neutralize the phytic acid aqueous solution with sodium hydroxide aqueous solution to obtain a partially neutralized phytic acid solution; The partially neutralized phytic acid solution is added to the chitosan acid sol in sections, and sodium hydroxide aqueous solution is added synchronously, and the reaction is allowed to mature to obtain a phytic acid-chitosan complex grafting material slurry;

[0010] (3) Dissolve dopamine hydrochloride in a buffer system composed of tris(hydroxymethyl) aminomethane and tris(hydroxymethyl) aminomethane hydrochloride, adjust the pH to 8.5 with sodium hydroxide aqueous solution, and allow the dopamine hydrochloride to oxidize and self-polymerize under open air conditions; Perform a first grafting reaction by adding sodium 2-mercaptoethanesulfonate to the resulting reaction solution, and then perform a second grafting reaction by adding an emulsion containing 1-dodecanethiol to obtain amphiphilic polydopamine dispersion;

[0011] (4) Add propylene glycol and alkyl polyglycoside to the phytic acid-chitosan complex grafting material slurry, then add the amphiphilic polydopamine dispersion, and then add sodium hydroxide aqueous solution for alkaline curing;

[0012] (5) Add sodium gluconate, trisodium citrate dihydrate, poly-(α,β)-DL-aspartic acid sodium salt, calcium lactate pentahydrate, and sodium oleate soap solution to the system obtained in step (4) in sequence, and add lactic acid aqueous solution;

[0013] (6) Add propylene glycol and silicone defoaming agent to the system obtained in step (5), add water to the predetermined total mass, mix and filter to obtain an environmentally friendly corrosion inhibitor concentrate for hydraulic support.

[0014] Preferably, the lactic acid aqueous solution is a lactic acid aqueous solution with a mass fraction of 85%; the phytic acid aqueous solution is a phytic acid aqueous solution with a mass fraction of 70%; and the sodium hydroxide aqueous solution is a sodium hydroxide aqueous solution with a mass fraction of 30%.

[0015] Preferably, in step (1), the chitosan is composed of high molecular weight chitosan and low molecular weight chitosan in a mass ratio of 0.95-1.15:0.4-0.55.

[0016] Preferably, the high molecular weight chitosan has a viscosity of 1120 mPa·s at 25°C in 1% acetic acid and a degree of deacetylation of 88.2%; the low molecular weight chitosan has a viscosity of 94 mPa·s at 25°C in 1% acetic acid.

[0017] Preferably, in step (1), based on a chitosan addition amount of 1.35-1.7 parts by weight, the amount of water added is 45 parts and the amount of lactic acid aqueous solution added is 0.7-0.9 parts.

[0018] Preferably, in step (2), the partially neutralized phytic acid solution is prepared by mixing water, phytic acid aqueous solution and sodium hydroxide aqueous solution in a mass ratio of 5.8-6.3:0.88-0.98:0.55-0.75.

[0019] Preferably, based on the amount of chitosan added (1.35-1.7 parts by mass), the segmented and synchronous addition in step (2) is as follows: first, 5.06-5.62 parts of the phytic acid solution are added dropwise within 30 minutes, and 1.2-1.55 parts of sodium hydroxide aqueous solution are added simultaneously; then, the remaining 2.17-2.41 parts of the phytic acid solution are added dropwise within 20 minutes.

[0020] Preferably, based on the amount of chitosan added (1.35-1.7 parts by mass), the oxidative self-polymerization of dopamine hydrochloride in step (3) is as follows: 4.5-5.5 parts of water, 0.003-0.005 parts of tris(hydroxymethyl)aminomethane and 0.001-0.003 parts of tris(hydroxymethyl)aminomethane hydrochloride are added to a container and stirred to form a buffer system. Then, 0.22-0.28 parts of dopamine hydrochloride are added and dissolved. The pH is adjusted to 8.5 with sodium hydroxide aqueous solution. The reaction is carried out at 25°C, 500 rpm, and open to air for 40 min to induce oxidative self-polymerization of dopamine.

[0021] Preferably, in step (3), the emulsion containing 1-dodecyl mercaptan is prepared by propylene glycol, alkyl polysaccharide, water and 1-dodecyl mercaptan in a mass ratio of 0.8-2.2:0.27-0.33:0.45-0.55:0.05-0.07.

[0022] Preferably, the alkyl polysaccharide is of the type Glucopon 600UP.

[0023] Preferably, in step (3), based on the amount of chitosan added (1.35-1.7 parts by weight), the amount of sodium 2-mercaptoethanesulfonate added is 0.16-0.2 parts, and the amount of emulsion containing 1-dodecanethiol added is 1.57-3.15 parts.

[0024] Preferably, based on the chitosan addition amount of 1.35-1.7 parts by weight, in step (4), the addition amount of propylene glycol is 4.5-5.5 parts; the addition amount of alkyl polysaccharide is 0.55-0.65 parts; the addition amount of amphoteric polydopamine dispersion is 7.454-9.138 parts; and the addition amount of sodium hydroxide aqueous solution is 2.6-3.4 parts.

[0025] Preferably, based on the amount of chitosan added (1.35-1.7 parts by weight), in step (5), the amount of sodium gluconate added is 2.7-3.3 parts; the amount of trisodium citrate dihydrate added is 1.8-2.2 parts; the amount of poly-(α,β)-DL-aspartic acid sodium salt added is 1.3-1.7 parts; the amount of calcium lactate pentahydrate added is 0.25-0.35 parts; the amount of sodium oleate soap solution added is 3.15-3.85 parts; and the amount of lactic acid aqueous solution added is 0.18-0.22 parts.

[0026] Preferably, in step (5), the sodium oleate soap solution is prepared by mixing sodium oleate and water at a mass ratio of 0.45-0.55:2.7-3.3.

[0027] Preferably, in step (6), based on a chitosan addition amount of 1.35-1.7 parts by weight, the addition amount of propylene glycol is 12.5-13.5 parts, and the addition amount of organosilicon defoamer is 0.08-0.12 parts.

[0028] Preferably, in step (6), the water is diluted to a total mass of 100 parts based on the amount of chitosan added (1.35-1.7 parts by weight).

[0029] Preferably, the silicone defoamer is of the type WACKER SRE CN.

[0030] The beneficial effects of this invention are:

[0031] The environmentally friendly corrosion inhibitor concentrate for hydraulic supports provided by this invention achieves synergistic effects through the ingenious formulation of its components and a specific preparation process. The working fluid formed after dilution of this concentrate can quickly spread and wet the surface of carbon steel such as Q355 steel, forming a dense, stable, and highly hydrophobic organic complex protective film. This protective film is firmly bonded to the metal substrate through multiple coordination bonds, effectively blocking the erosion of water molecules, oxygen, and corrosive ions, significantly reducing the corrosion rate of the metal, and exhibiting excellent corrosion inhibition performance. Even under harsh environments such as simulated salt spray, it can effectively inhibit the spread of rust, providing a reliable guarantee for the long-term stable operation of hydraulic supports.

[0032] This invention provides a robust three-dimensional network structure for the entire protective film system by constructing a unique phytic acid-chitosan complex grafted framework. The active groups in this framework can undergo strong multi-point coordination adsorption with the metal surface, enhancing the adhesion strength and coverage uniformity of the film. Simultaneously, the introduced amphoteric polydopamine dispersion further strengthens interfacial adhesion; its active groups can interpenetrate and crosslink within the complex framework, filling potential defects and resulting in a more continuous and complete protective film, significantly improving its physical barrier properties and erosion resistance.

[0033] The protective film formed by this invention possesses excellent hydrophobic properties. This is due to the directional arrangement and enrichment of hydrophobic segments in the system, which constructs a low surface energy barrier on the outer layer of the film. This hydrophobic layer can effectively repel water molecules, reduce the wettability of the medium on the metal surface, and thus weaken the conditions for electrochemical corrosion from the source. This combination of hydrophobicity and strong adsorption of the underlying layer forms a gradient protective structure, further consolidating the overall corrosion inhibition effect.

[0034] The concentrate prepared by this invention exhibits excellent system stability and application performance. Its working fluid displays balanced foaming and defoaming characteristics, avoiding the adverse effects of excessive foam on the hydraulic system. After undergoing thermal cycling, the system remains homogeneous and stable, rarely exhibiting stratification or sedimentation, ensuring the reliability and performance durability of the product during storage and use. The good compatibility and synergistic effect among the components make this concentrate environmentally friendly, while simultaneously meeting the long-term, high-stability operation requirements of hydraulic support systems for the transmission medium.

[0035] In summary, this invention not only achieves efficient and environmentally friendly corrosion inhibition and protection, but also significantly improves film quality, interfacial bonding strength, hydrophobic properties, and system stability. It has excellent overall performance and promising application prospects. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0037] The lactic acid aqueous solution used in this invention is an 85% (w / w) lactic acid aqueous solution; the phytic acid aqueous solution is a 70% (w / w) phytic acid aqueous solution; the sodium hydroxide aqueous solution is a 30% (w / w) sodium hydroxide aqueous solution. Tris(hydroxymethyl)aminomethane, tris(hydroxymethyl)aminomethane hydrochloride, dopamine hydrochloride, sodium 2-mercaptoethanesulfonate, 1-dodecanethiol, propylene glycol, sodium gluconate, trisodium citrate dihydrate, calcium lactate pentahydrate, and sodium oleate can all be purchased through conventional commercial channels, preferably with a purity of not less than 95%. The deionized water has a conductivity of no more than 5 μS / cm; the high molecular weight chitosan is from Sigma-Aldrich, catalog number C434553, with a viscosity of 1120 mPa·s at 25℃ in 1% acetic acid and a degree of deacetylation of 88.2%; the low molecular weight chitosan is from Sigma-Aldrich, catalog number C434547, with a viscosity of 94 mPa·s at 25℃ in 1% acetic acid and a degree of deacetylation of 90.9%; the alkyl polysaccharide is from BASF, model Glucopon 600UP; the sodium poly-(α,β)-DL-aspartate is from Sigma-Aldrich, catalog number P477791, with a molar weight of 5000; the silicone defoamer is from WACKER, model WACKERSRE CN.

[0038] Example 1:

[0039] S1: Add 45kg of deionized water to the stirred tank, start stirring to 500rpm, add 700g of lactic acid and stir for 10min, then add 950g of high molecular weight chitosan and 400g of low molecular weight chitosan, maintain 25℃ and continue stirring for 2h to obtain chitosan acid sol.

[0040] In step S2, 5800g of deionized water was added to another container, and after stirring at 300rpm, 880g of phytic acid aqueous solution was added. Then, 550g of sodium hydroxide aqueous solution was added dropwise while controlling the temperature to not exceed 30℃ to obtain a partially neutralized phytic acid solution. Subsequently, the chitosan acid sol obtained in step S1 was stirred at 800rpm. 5060g of the partially neutralized phytic acid solution was added dropwise over 30min, and 1200g of sodium hydroxide aqueous solution was added dropwise simultaneously. Then, the stirring was reduced to 300rpm and the remaining 2170g of the partially neutralized phytic acid solution was added dropwise over 20min. After the addition was completed, stirring was continued for 30min and the mixture was allowed to stand for 20min to mature, resulting in a phytic acid-chitosan complex graft slurry.

[0041] S3: Add 4.5 kg of deionized water to the third container, then add 3 g of tris(hydroxymethyl)aminomethane and 1 g of tris(hydroxymethyl)aminomethane hydrochloride and stir for 10 min to prepare a buffer system. Then add 220 g of dopamine hydrochloride and stir for 5 min to dissolve. Adjust the pH of the solution to 8.5 with sodium hydroxide aqueous solution. React at 25℃, 500 rpm, and open to air for 40 min to allow dopamine to undergo oxidative self-polymerization. Then add 160 g of sodium 2-mercaptoethanesulfonate and continue stirring for 30 min to complete the first grafting. In another container, add 1800 g of propylene glycol and 270 g of alkyl polysaccharide and stir evenly. Then add 450 g of deionized water and 50 g of 1-dodecylthiol and emulsify at 1000 rpm for 10 min to form a stable emulsion. Add this emulsion dropwise to the reaction solution of the first grafting over 20 min and continue to react at 25℃ and 500 rpm for 60 min to obtain an amphoteric polydopamine dispersion.

[0042] S4: Maintain the slurry obtained in step S2 at 25°C and set the stirring speed to 400 rpm. Add 4500 g of propylene glycol and 550 g of alkyl polysaccharide and stir for 20 min. Then, add 7454 g of amphoteric polydopamine dispersion over 30 min. After the addition is complete, add 2600 g of sodium hydroxide aqueous solution dropwise over 40 min while controlling the temperature not to exceed 30°C. Continue stirring at 400 rpm for 2 h. Then, stop heating and allow it to naturally cool down to 25°C. Add 2700 g of sodium gluconate and 1800 g of tricitric acid in sequence. Sodium dihydrate was stirred for 30 min to fully dissolve it and establish the first complexation buffer system. Then, 1300 g of poly-(α,β)-DL-aspartic acid sodium salt was added and stirred for 30 min. Subsequently, 250 g of calcium lactate pentahydrate was added and stirred for 20 min. Then, 450 g of sodium oleate and 2700 g of deionized water were added to a container and stirred at 40 °C for 10 min to form a homogeneous soap solution. The solution was then cooled to 25 °C and added dropwise to the main vessel over 15 min while stirring for another 30 min. Finally, 180 g of lactic acid aqueous solution was added.

[0043] S5: After step S4 is completed, reduce the stirring speed to 300 rpm, add 12500 g of propylene glycol and 80 g of silicone defoamer and stir for 20 min, then add deionized water to make up the volume to 100 kg of the finished product. Continue stirring for 30 min and then filter at 100 µm to obtain an environmentally friendly corrosion inhibitor concentrate for hydraulic supports.

[0044] Example 2:

[0045] S1: Add 45kg of deionized water to the stirred tank, start stirring to 500rpm, add 800g of lactic acid and stir for 10min, then add 1050g of high molecular weight chitosan and 450g of low molecular weight chitosan, maintain 25℃ and continue stirring for 2h to obtain chitosan acid sol.

[0046] In step S2, 6020g of deionized water was added to another container, and after stirring at 300 rpm, 930g of phytic acid aqueous solution was added. Then, 650g of sodium hydroxide aqueous solution was added dropwise while controlling the temperature to not exceed 30℃ to obtain a partially neutralized phytic acid solution. Subsequently, the chitosan acid sol obtained in step S1 was stirred at 800 rpm. 5320g of the partially neutralized phytic acid solution was added dropwise over 30 min, and 1350g of sodium hydroxide aqueous solution was added dropwise simultaneously. Then, the stirring was reduced to 300 rpm and the remaining 2280g of the partially neutralized phytic acid solution was added dropwise over 20 min. After the addition was completed, stirring was continued for 30 min and the mixture was allowed to stand for 20 min to mature, resulting in a phytic acid-chitosan complex graft slurry.

[0047] S3: Add 5 kg of deionized water to the third container, then add 4 g of tris(hydroxymethyl)aminomethane and 2 g of tris(hydroxymethyl)aminomethane hydrochloride and stir for 10 min to prepare a buffer system. Then add 250 g of dopamine hydrochloride and stir for 5 min to dissolve. Adjust the pH of the solution to 8.5 with sodium hydroxide aqueous solution. React at 25℃, 500 rpm, and open to air for 40 min to allow dopamine to undergo oxidative self-polymerization. Then add 180 g of sodium 2-mercaptoethanesulfonate and continue stirring for 30 min to complete the first grafting. In another container, add 2000 g of propylene glycol and 300 g of alkyl polysaccharide and stir evenly. Then add 500 g of deionized water and 60 g of 1-dodecylthiol and emulsify at 1000 rpm for 10 min to form a stable emulsion. Add this emulsion dropwise to the reaction solution of the first grafting over 20 min and continue to react at 25℃ and 500 rpm for 60 min to obtain an amphoteric polydopamine dispersion.

[0048] S4: Maintain the slurry obtained in step S2 at 25°C and set the stirring speed to 400 rpm. Add 5000 g of propylene glycol and 600 g of alkyl polysaccharide and stir for 20 min. Then, add 8296 g of amphoteric polydopamine dispersion over 30 min. After the addition is complete, add 3000 g of sodium hydroxide aqueous solution dropwise over 40 min, controlling the temperature to not exceed 30°C. Continue stirring at 400 rpm for 2 h. Then, stop heating and allow it to naturally cool down to 25°C. Add 3000 g of sodium gluconate and 2000 g of tricitric acid in sequence. Sodium dihydrate was stirred for 30 min to fully dissolve and establish the first complexation buffer system. Then, 1500 g of poly-(α,β)-DL-aspartic acid sodium salt was added and stirred for 30 min. Subsequently, 300 g of calcium lactate pentahydrate was added and stirred for 20 min. Then, 500 g of sodium oleate and 3000 g of deionized water were added to a container and stirred at 40 °C for 10 min to form a homogeneous soap solution. The solution was then cooled to 25 °C and added dropwise to the main vessel over 15 min while stirring for another 30 min. Finally, 200 g of lactic acid aqueous solution was added.

[0049] S5: After step S4 is completed, reduce the stirring speed to 300 rpm, add 13000 g of propylene glycol and 100 g of silicone defoamer and stir for 20 min, then add deionized water to make up the volume to 100 kg of the finished product. Continue stirring for 30 min and then filter at 100 µm to obtain an environmentally friendly corrosion inhibitor concentrate for hydraulic supports.

[0050] Example 3:

[0051] S1: Add 45kg of deionized water to the mixing tank, start stirring to 500rpm, add 900g of lactic acid and stir for 10min, then add 1150g of high molecular weight chitosan and 550g of low molecular weight chitosan, maintain 25℃ and continue stirring for 2h to obtain chitosan acid sol.

[0052] In step S2, 6300g of deionized water was added to another container, and after stirring at 300rpm, 980g of phytic acid aqueous solution was added. Then, 750g of sodium hydroxide aqueous solution was added dropwise while controlling the temperature to not exceed 30℃ to obtain a partially neutralized phytic acid solution. Subsequently, the chitosan acid sol obtained in step S1 was stirred at 800rpm. 5620g of the partially neutralized phytic acid solution was added dropwise over 30min, and 1550g of sodium hydroxide aqueous solution was added dropwise simultaneously. Then, the stirring was reduced to 300rpm and the remaining 2410g of the partially neutralized phytic acid solution was added dropwise over 20min. After the addition was completed, stirring was continued for 30min and the mixture was allowed to stand for 20min to mature, resulting in a phytic acid-chitosan complex graft slurry.

[0053] S3: Add 5.5 kg of deionized water to the third container, then add 5 g of tris(hydroxymethyl)aminomethane and 3 g of tris(hydroxymethyl)aminomethane hydrochloride and stir for 10 min to prepare a buffer system. Then add 280 g of dopamine hydrochloride and stir for 5 min to dissolve. Adjust the pH of the solution to 8.5 with sodium hydroxide aqueous solution. React at 25℃, 500 rpm, and open to air for 40 min to induce oxidative self-polymerization of dopamine. Then add 200 g of sodium 2-mercaptoethanesulfonate and continue stirring for 30 min to complete the first grafting. In another container, add 2200 g of propylene glycol and 330 g of alkyl polysaccharide and stir evenly. Then add 550 g of deionized water and 70 g of 1-dodecylthiol and emulsify at 1000 rpm for 10 min to form a stable emulsion. Add this emulsion dropwise to the reaction solution of the first grafting over 20 min and continue to react at 25℃ and 500 rpm for 60 min to obtain an amphoteric polydopamine dispersion.

[0054] S4: Maintain the slurry obtained in step S2 at 25°C and set the stirring speed to 400 rpm. Add 5500 g of propylene glycol and 650 g of alkyl polysaccharide and stir for 20 min. Then, add 9138 g of amphoteric polydopamine dispersion over 30 min. After the addition is complete, add 3400 g of sodium hydroxide aqueous solution dropwise over 40 min while controlling the temperature not to exceed 30°C. Continue stirring at 400 rpm for 2 h. Then, stop heating and allow it to naturally cool down to 25°C. Add 3300 g of sodium gluconate and 2200 g of lemon juice in sequence. Stir the trisodium oleate dihydrate for 30 minutes to fully dissolve it and establish the first complexation buffer system. Then, add 1700g of poly-(α,β)-DL-aspartic acid sodium salt and stir for 30 minutes. Next, add 350g of calcium lactate pentahydrate and stir for 20 minutes. Then, take a container and add 550g of sodium oleate and 3300g of deionized water. Stir at 40°C for 10 minutes to form a homogeneous soap solution. Cool to 25°C and add the soap solution dropwise to the main reactor over 15 minutes while continuing to stir for 30 minutes. Finally, add 220g of lactic acid.

[0055] S5: After step S4 is completed, reduce the stirring speed to 300 rpm, add 13500 g of propylene glycol and 120 g of silicone defoamer and stir for 20 min. Then add deionized water to make up the volume so that the total mass of the finished product is 100 kg. Continue stirring for 30 min and then filter at 100 µm to obtain an environmentally friendly corrosion inhibitor concentrate for hydraulic supports.

[0056] Comparative Example 1:

[0057] The difference between Comparative Example 1 and Example 2 is that in step S1, 45 kg of deionized water was added to the stirred tank, the stirring was started at 500 rpm, 800 g of lactic acid was added and stirred for 10 min, then 1500 g of high molecular weight chitosan was added, the temperature was maintained at 25 °C and stirring was continued for 2 h to obtain chitosan acid sol; the remaining conditions were the same as in Example 2.

[0058] Comparative Example 2:

[0059] The difference between Comparative Example 2 and Example 2 is that in step S2, when preparing the partially neutralized phytic acid solution, instead of adding 650g of sodium hydroxide aqueous solution, 650g of deionized water is added, and the temperature is controlled to be no higher than 30°C to obtain an unneutralized phytic acid solution before proceeding with the subsequent synchronous and segmented addition operations; the other conditions are the same as in Example 2.

[0060] Comparative Example 3:

[0061] The difference between Comparative Example 3 and Example 2 is that in step S3, after the oxidative self-polymerization of dopamine under the conditions of 25°C, 500 rpm and open contact with air for 40 min, 180 g of sodium 2-mercaptoethanesulfonate is not added, but 180 g of deionized water is added, and the mixture is stirred at 25°C and 500 rpm for 30 min before the subsequent emulsion is added and reacted; the other conditions are the same as in Example 2.

[0062] Comparative Example 4:

[0063] The difference between Comparative Example 4 and Example 2 is that, in step S3, when preparing the emulsion, instead of adding 60g of 1-dodecylthiol, 60g of deionized water is added, and the emulsion is formed at 1000rpm for 10min. Then, it is added dropwise to the aforementioned reaction solution within 20min and the reaction continues; the other conditions are the same as in Example 2.

[0064] Comparative Example 5:

[0065] The difference between Comparative Example 5 and Example 2 is that in step S4, after adding 5000g of propylene glycol and 600g of alkyl polysaccharide and stirring for 20min, the amphoteric polydopamine dispersion is not added first. Instead, 3000g of sodium gluconate and 2000g of trisodium citrate dihydrate are added sequentially and stirred for 30min to fully dissolve them. Then, 8296g of amphoteric polydopamine dispersion is added within 30min, followed by alkaline dripping curing and subsequent feeding. The remaining conditions are the same as in Example 2.

[0066] Comparative Example 6:

[0067] The difference between Comparative Example 6 and Example 2 is that in step S4, after adding 8296g of amphoteric polydopamine dispersion within 30min, instead of adding 3000g of sodium hydroxide aqueous solution within 40min, 3000g of deionized water was added within 40min, and the temperature was controlled to not exceed 30℃. Then, the reaction was continued with stirring at 400rpm for 2h and subsequent feeding was carried out. The other conditions were the same as in Example 2.

[0068] Comparative Example 7:

[0069] The difference between Comparative Example 7 and Example 2 is that in step S4, after adding 1500g of sodium poly-(α,β)-DL-aspartate and stirring for 30 min, instead of adding 300g of calcium lactate pentahydrate first, 500g of sodium oleate and 3000g of deionized water are stirred at 40°C for 10 min to form a homogeneous soap solution, which is then cooled to 25°C and added dropwise to the main vessel within 15 min while stirring for another 30 min. Then, 300g of calcium lactate pentahydrate is added and stirred for 20 min before lactic acid is added. The remaining conditions are the same as in Example 2.

[0070] Performance testing:

[0071] Sample preparation: Environmentally friendly corrosion inhibitor concentrates for hydraulic supports were prepared according to Examples and Comparative Example 1, respectively. After obtaining the final product, all were filtered through a 100µm filter. The working solution for application performance testing was prepared at a mass fraction of 3.0%. Specifically, 150g of each concentrate was weighed and added to deionized water to a total mass of 5000g. The solution was stirred at 25℃ and 400rpm for 30min and then allowed to stand for 2h to remove bubbles. These were recorded as the working solution for Examples and the working solution for Comparative Example, respectively. All metal-related samples were made of Q355 steel from the same batch. The sample surfaces were wet-polished with 400-mesh, 800-mesh, and 1200-mesh sandpaper in sequence. After rinsing with deionized water, the samples were sonicated with anhydrous ethanol for 5min and then dried.

[0072] Physicochemical properties (acidity, alkalinity, kinematic viscosity, surface tension): Acidity (pH) was measured according to GB / T 9724-2007. The pH of each working solution was calibrated at 25℃ using standard buffer solutions at pH=6.86 and pH=9.18, and the average of three parallel measurements was taken. Kinematic viscosity was measured according to GB / T 265-1988. The kinematic viscosity ν40 of each working solution was measured using a 40℃ constant temperature bath and an Ubbelohde viscometer. Surface tension was measured according to GB / T 5549-2010. The surface tension γ of each working solution was measured at 25℃ using the film-pulling method. The measurements were repeated five times, and the arithmetic mean was taken.

[0073] Corrosion inhibition performance: According to GB / T 18175-2014, a rotating plate device was used. The sample was Q355 steel (50mm×25mm×2mm). The edges and back were sealed with epoxy resin, leaving only the front 50mm×25mm single-sided exposed area of ​​12.50cm². 2 Add 1000 mL of each working solution to a constant-temperature glass container and maintain the temperature at (45±1) ℃. After installing the sample, rotate it at (120±5) r / min for 72 h to simulate the cyclic scouring condition. After the test, remove the sample, rinse with deionized water, and immerse it in 10% hydrochloric acid (with 0.5% hexamethylenetetramine added as a corrosion inhibitor) for 30 s to remove corrosion products. Then rinse with deionized water, rinse with anhydrous ethanol, and dry at 60 ℃ for 30 min. After cooling to room temperature, weigh it. Calculate the corrosion rate V = 87.6 × Δm / (ρ × A × t), where Δm is the weight loss and ρ is taken as 7.85 g / cm³. 3 A is 12.50cm 2 The time interval is 72 hours, and the corrosion inhibition rate η = (V0−V) / V0×100% is calculated, where V0 is the corrosion rate under the condition of deionized water blank working solution (without concentrate).

[0074] Electrochemical impedance spectroscopy: Using the same three-electrode system and electrolyte as the polarization curve, the working electrode was immersed in the corresponding working solution for 2 hours and then EIS was performed at open circuit potential. The AC perturbation amplitude was 10mV, the frequency range was 100kHz-0.01Hz, and 10 points were taken every tenth harmonic. The impedance spectrum was fitted with an equivalent circuit to obtain the low-frequency modulus |Z| 0.01Hz.

[0075] Film-forming hydrophobicity: According to GB / T 30447-2013, Q355 steel test pieces (30mm×30mm×2mm) were polished and cleaned as described above, then immersed in the corresponding working solution for 5 minutes. After being taken out and hung vertically to drip dry for 5 minutes, they were placed in an oven at (50±1)℃ to dry for 2 hours to form a surface film layer. A contact angle measuring instrument was used to add a drop of deionized water (volume 3.0µL) at (25±1)℃ and (50±5)% relative humidity. The static contact angle was read after 60 seconds of contact with the droplet and the measurement was repeated 5 times and the arithmetic mean was taken.

[0076] Salt spray test: According to GB / T 10125-2021, Q355 steel test pieces prepared and dried to form a film were used as samples for the film hydrophobicity test. The edges of the samples were sealed with neutral silicone sealant to avoid edge effects. A neutral salt spray test was conducted in a salt spray chamber. The spray solution was a 5.0% sodium chloride solution by mass, the test temperature was (35±1)℃, and the spraying was continuous for 240h. After the test, the samples were taken out, gently rinsed with deionized water, and allowed to air dry for 2h. The percentage of rust area was calculated using image analysis software.

[0077] Foaming characteristics: According to GB / T 12579-2002, 200 mL of the working solution of the examples and comparative examples were placed in the measuring cylinder of the foaming apparatus. The following steps were performed in sequence: Section I (24℃) for 5 min of aeration and 10 min of standing; Section II (93.5℃) for 5 min of constant temperature foaming and 10 min of standing; and Section III (24℃) for 5 min of reheating and 10 min of foaming. The foaming volume (0 min) and the foam volume after defoaming (10 min) were recorded for each section. The 0 min / 10 min of Section I was used as the foaming and defoaming index at room temperature.

[0078] Stratification and sedimentation: According to MT / T 76-2011, each concentrate was prepared into a working solution of 500 mL at a mass fraction of 3.0%, placed in a graduated 500 mL graduated cylinder and sealed. The solution was placed in a constant temperature oven at (54±2)℃ for 24 h and in an environment at (0±2)℃ for 24 h respectively. After being removed and allowed to stand at (25±1)℃ for 2 h, the supernatant stratification height (mm) was read. The test results are shown in Table 1.

[0079] Table 1 Performance Test Results

[0080]

[0081] Data Analysis:

[0082] As can be seen from the data in Examples 1-3 of Table 1, the environmentally friendly corrosion inhibitor concentrate for hydraulic supports prepared in this invention maintains suitable weak alkalinity and near-water-based fluidity after dilution into a working fluid, while also possessing low surface tension to facilitate rapid wetting and spreading on Q355 steel surfaces. Its corrosion rate is significantly reduced, and the low-frequency modulus of the electrochemical impedance spectroscopy remains at a high level, indicating that the complex grafted framework formed by phytic acid and chitosan can provide multi-point coordination adsorption on the metal surface. Combined with the strong interfacial adhesion of the amphoteric polydopamine dispersion, a dense organic complex protective film is constructed. The outer layer of this protective film forms a continuous hydrophobic barrier under the synergistic effect of sodium oleate and propylene glycol, increasing the contact angle and inhibiting corrosion propagation under salt spray conditions. Simultaneously, the interfacial regulation of the organosilicon defoamer and alkyl polysaccharide glycosides maintains a balance between foaming and defoaming performance, and exhibits minimal stratification and sedimentation after thermal cycling, meeting the stability requirements of long-term cyclic use of hydraulic support systems.

[0083] As can be seen from the data in Table 1 for Example 2 and Comparative Example 1, when only high molecular weight chitosan is used and low molecular weight chitosan is lacking, the rheological properties and dispersion stability of the system are more easily affected by molecular chain entanglement, leading to a decrease in the migration of the complex graft in the working fluid and making it difficult to form a continuous and uniform coating layer on the Q355 steel surface. The result is a decrease in the low-frequency modulus of the electrochemical impedance spectroscopy, an increase in the corrosion rate, and more pronounced stratification and sedimentation after thermal cycling. It is worth noting that the higher system viscosity inhibits bubble coalescence to some extent, which may lead to localized improvement in foaming indicators, but this improvement cannot compensate for the corrosion inhibition gap caused by insufficient film density.

[0084] As can be seen from the data in Table 1 for Example 2 and Comparative Example 2, when the phytic acid solution participates in the complexation grafting without partial neutralization by sodium hydroxide, the high acidity of the phytic acid causes excessive protonation of the chitosan amino groups and induces rapid flocculation. The complexation grafting framework exhibits localized dense aggregation and structural inhomogeneity during the formation stage. This structural defect weakens the subsequent embedding and solidification efficiency of the amphoteric polydopamine dispersion, reducing the continuity and adhesion strength of the protective film. This manifests as an increased corrosion rate, expanded salt spray corrosion area, and more significant stratification and sedimentation under thermal cycling. This demonstrates the crucial role of partial neutralization and controllable complexation in corrosion inhibition.

[0085] As can be seen from the data in Table 1 for Example 2 and Comparative Example 3, when the sodium 2-mercaptoethanesulfonate segment is missing from the amphoteric polydopamine dispersion, although the surface hydrophobicity can be locally improved due to the enrichment of hydrophobic segments and sodium oleate, the low-frequency modulus of the electrochemical impedance spectroscopy and the corrosion inhibition rate are still significantly reduced, and the salt spray corrosion area increases, showing an increase in contact angle and a decrease in corrosion resistance. The main reason is that the hydrophilic anchoring and electrolyte compatibility provided by sodium 2-mercaptoethanesulfonate help the polydopamine dispersion spread evenly and fill microporous defects. Its absence easily leads to the formation of discontinuous hydrophobic patches, causing water and chloride ions to invade along the defect channels. This result indicates that the bi-segment grafting of sulfonate segments and hydrophobic segments has a significant synergistic effect in interface regulation.

[0086] As can be seen from the data in Example 2 and Comparative Example 4 in Table 1, when the 1-dodecylthiol segment is missing from the amphoteric polydopamine dispersion, the water contact angle after film formation decreases and the salt spray corrosion area expands. Simultaneously, the low-frequency modulus of the electrochemical impedance spectroscopy decreases and the corrosion rate increases. The main reason for this is that the hydrophobic long chain provided by 1-dodecylthiol can construct a low surface energy outer layer on the metal surface, forming a hydrophobic barrier-wetting spreading gradient structure together with the soap solution formed by sodium oleate. Without this segment, the film layer is more prone to water absorption and swelling, generating ion migration channels, resulting in a significant decrease in the corrosion inhibition effect's resistance to the salt spray environment.

[0087] As can be seen from the data in Example 2 and Comparative Example 5 in Table 1, when sodium gluconate, sodium citrate, and sodium poly-(α,β)-DL-aspartate are added before the amphoteric polydopamine dispersion, the carboxylate ligands in the system preferentially form complexes with the phytic acid-chitosan complex grafting backbone and metal ions, thereby weakening the adhesion, solidification, and network penetration of polydopamine at the interface, resulting in insufficient interlayer bonding and density of the protective film. In this case, the foaming and defoaming properties may improve to some extent due to changes in electrolyte strength, but the corrosion rate and salt spray corrosion area still show unfavorable changes.

[0088] As can be seen from the data in Table 1 for Example 2 and Comparative Example 6, when the amphoteric polydopamine dispersion is introduced without alkaline curing with sodium hydroxide aqueous solution, although the system exhibits less stratification and sedimentation after thermal cycling due to the reduced degree of crosslinking, its corrosion rate increases and the low-frequency modulus of the electrochemical impedance spectroscopy decreases, indicating insufficient chemical fixation and interfacial adhesion of the film. This is because alkaline conditions facilitate the reaction and network rearrangement between the active groups of polydopamine and the chitosan amine groups, locking the complexed grafted framework onto the metal surface and sealing ion migration channels. Without this step, the film is more susceptible to shearing by the working fluid and corrosion by the salt spray medium, making it difficult to fully release the synergistic effect.

[0089] As can be seen from the data in Example 2 and Comparative Example 7 in Table 1, when sodium oleate soap solution is added before calcium lactate pentahydrate, calcium ions readily undergo rapid saponification with oleate ions, generating insoluble calcium soap particles. This leads to significant stratification and sedimentation in the system, while simultaneously reducing the directional alignment ability of effective sodium oleate on the metal surface, resulting in a discontinuous hydrophobic barrier. This structural defect further affects the synergistic film formation of the amphoteric polydopamine dispersion and the phytic acid-chitosan complex grafted framework, manifested as a decrease in the low-frequency modulus of the electrochemical impedance spectroscopy, an increase in the corrosion rate, and an expansion of the salt spray corrosion area. Therefore, the slow-release calcium source of calcium lactate pentahydrate should be introduced before the saponification components to achieve a corrosion inhibition effect greater than the sum of its parts (1+1>2) through multi-component complex adsorption.

[0090] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention is limited to these examples; within the framework of the invention, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of the different aspects of the invention as described above, which are not provided in detail for the sake of brevity.

Claims

1. A method for preparing an environmentally friendly corrosion inhibitor concentrate for hydraulic supports, characterized in that, Includes the following steps: (1) Add lactic acid aqueous solution to water and stir, then add chitosan to obtain chitosan acid sol; (2) Mix phytic acid aqueous solution with sodium hydroxide aqueous solution to partially neutralize it, and obtain a partially neutralized phytic acid solution; add the partially neutralized phytic acid solution dropwise to the chitosan acid sol in segments, and add sodium hydroxide aqueous solution dropwise at the same time, react and mature to obtain phytic acid-chitosan complex graft slurry; (3) Add dopamine hydrochloride to a buffer system composed of tris(hydroxymethyl)aminomethane and tris(hydroxymethyl)aminomethane hydrochloride and dissolve it. Adjust the pH to 8.5 with sodium hydroxide aqueous solution and allow the dopamine hydrochloride to oxidize and self-polymerize under open contact with air. Add sodium 2-mercaptoethanesulfonate to the resulting reaction solution for the first grafting reaction, and then add an emulsion containing 1-dodecylthiol for the second grafting reaction to obtain a hydrophilic-reactive polydopamine dispersion. (4) Add propylene glycol and alkyl polysaccharide to the phytic acid-chitosan complex graft slurry, then add the amphoteric polydopamine dispersion, and then add sodium hydroxide aqueous solution for alkaline curing; (5) Add sodium gluconate, trisodium citrate dihydrate, poly-(α,β)-DL-aspartic acid sodium salt, calcium lactate pentahydrate and sodium oleate soap solution to the system obtained in step (4) in sequence, and add lactic acid aqueous solution; (6) Add propylene glycol and silicone defoamer to the system obtained in step (5), add water to the predetermined total mass, stir and mix and filter to obtain an environmentally friendly corrosion inhibitor concentrate for hydraulic supports; In step (3), the emulsion containing 1-dodecylthiol is prepared by mixing propylene glycol, alkyl polysaccharide, water and 1-dodecylthiol in a mass ratio of 0.8-2.2:0.27-0.33:0.45-0.55:0.05-0.

07. Based on a chitosan addition of 1.35-1.7 parts by weight, in step (3), the addition of sodium 2-mercaptoethanesulfonate is 0.16-0.2 parts, and the addition of emulsion containing 1-dodecanethiol is 1.57-3.15 parts; Based on a chitosan addition of 1.35-1.7 parts by mass, in step (4), the addition of propylene glycol is 4.5-5.5 parts; the addition of alkyl polysaccharide is 0.55-0.65 parts; the addition of amphoteric polydopamine dispersion is 7.454-9.138 parts; and the addition of sodium hydroxide aqueous solution is 2.6-3.4 parts.

2. The method for preparing the environmentally friendly corrosion inhibitor concentrate for hydraulic supports according to claim 1, characterized in that, The lactic acid aqueous solution is an 85% lactic acid aqueous solution; the phytic acid aqueous solution is a 70% phytic acid aqueous solution; and the sodium hydroxide aqueous solution is a 30% sodium hydroxide aqueous solution.

3. The method for preparing the environmentally friendly corrosion inhibitor concentrate for hydraulic supports according to claim 1, characterized in that, In step (1), the chitosan is composed of high molecular weight chitosan and low molecular weight chitosan in a mass ratio of 0.95-1.15:0.4-0.55; the high molecular weight chitosan has a viscosity of 1120 mPa·s at 25°C in 1% acetic acid and a degree of deacetylation of 88.2%; the low molecular weight chitosan has a viscosity of 94 mPa·s at 25°C in 1% acetic acid.

4. The method for preparing the environmentally friendly corrosion inhibitor concentrate for hydraulic supports according to claim 1, characterized in that, Based on a chitosan addition amount of 1.35-1.7 parts by weight, in step (1), the amount of water added is 45 parts and the amount of lactic acid aqueous solution added is 0.7-0.9 parts.

5. The method for preparing the environmentally friendly corrosion inhibitor concentrate for hydraulic supports according to claim 1, characterized in that, In step (2), the partially neutralized phytic acid solution is prepared by mixing water, phytic acid aqueous solution and sodium hydroxide aqueous solution in a mass ratio of 5.8-6.3:0.88-0.98:0.55-0.

75. Based on the amount of chitosan added, which is 1.35-1.7 parts by mass, the segmented and synchronous addition in step (2) is as follows: first, 5.06-5.62 parts of the partially neutralized phytic acid solution are added dropwise over 30 minutes, and 1.2-1.55 parts of sodium hydroxide aqueous solution are added dropwise simultaneously. Then, 2.17-2.41 parts of the partially neutralized phytic acid solution are added dropwise over 20 minutes.

6. The method for preparing the environmentally friendly corrosion inhibitor concentrate for hydraulic supports according to claim 1, characterized in that, Based on the amount of chitosan added (1.35-1.7 parts by mass), the oxidative self-polymerization of dopamine hydrochloride in step (3) is as follows: 4.5-5.5 parts of water, 0.003-0.005 parts of tris(hydroxymethyl)aminomethane and 0.001-0.003 parts of tris(hydroxymethyl)aminomethane hydrochloride are added to a container and stirred to form a buffer system. Then, 0.22-0.28 parts of dopamine hydrochloride are added and dissolved. The pH is adjusted to 8.5 with sodium hydroxide aqueous solution. The reaction is carried out at 25°C, 500 rpm, and open to air for 40 min to induce oxidative self-polymerization of dopamine.

7. The method for preparing the environmentally friendly corrosion inhibitor concentrate for hydraulic supports according to claim 1, characterized in that, The alkyl polysaccharide is designated as Glucopon 600UP; the silicone defoamer is designated as WACKER SRE CN.

8. The method for preparing the environmentally friendly corrosion inhibitor concentrate for hydraulic supports according to claim 1, characterized in that, Based on a chitosan addition of 1.35-1.7 parts by weight, in step (5), the addition amount of sodium gluconate is 2.7-3.3 parts; the addition amount of trisodium citrate dihydrate is 1.8-2.2 parts; the addition amount of poly-(α,β)-DL-aspartic acid sodium salt is 1.3-1.7 parts; the addition amount of calcium lactate pentahydrate is 0.25-0.35 parts; the addition amount of sodium oleate soap solution is 3.15-3.85 parts; the addition amount of lactic acid aqueous solution is 0.18-0.22 parts; the sodium oleate soap solution is prepared by mixing sodium oleate and water at a mass ratio of 0.45-0.55:2.7-3.

3.

9. The method for preparing the environmentally friendly corrosion inhibitor concentrate for hydraulic supports according to claim 1, characterized in that, Based on the chitosan addition of 1.35-1.7 parts by weight, in step (6), the amount of propylene glycol added is 12.5-13.5 parts; the amount of organosilicon defoamer added is 0.08-0.12 parts; and the water is diluted to make the total mass of the finished product 100 parts.

10. An environmentally friendly corrosion inhibitor concentrate for hydraulic supports, characterized in that, It is obtained by the preparation method of the environmentally friendly corrosion inhibitor concentrate for hydraulic supports according to any one of claims 1-9.

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