Environment-friendly concentrated solution with self-repairing capability for hydraulic support and preparation method of concentrated solution

Abstract

The invention discloses a self-repairing concentrated solution for an environment-friendly hydraulic support and a preparation method of the self-repairing concentrated solution. The self-repairing concentrated solution comprises the following components in percentage by mass: 5-10% of a lubricant, 8-18% of a self-repairing corrosion inhibitor, 4-8% of an emulsifier, 1-3% of a water softener, 0.05-0.08% of a defoaming agent and the balance of water. The bio-based beta-cyclodextrin is used as a carrier, the sebacic acid bicyclo-imidazoline is used as a core material, the corrosion inhibitor with the self-repairing function is synthesized through self-assembly, self-repairing of a micro-damage area of a hydraulic support can be achieved, and therefore the long-acting corrosion prevention effect is achieved; according to the invention, cerium-doped graphene oxide modified triethanolamine oleate is adopted as a lubricant, so that the lubricity and stability of the concentrated solution can be effectively improved, and the lubricant and the self-repairing corrosion inhibitor can play a role in synergistic corrosion prevention, so that the long-acting corrosion resistance of the concentrated solution is further improved, and the COD (Chemical Oxygen Demand) value of the concentrated solution is effectively reduced.

Description

Technical Field

[0001] This invention belongs to the field of transmission medium for hydraulic supports in coal mines. Specifically, this invention relates to an environmentally friendly concentrated fluid for hydraulic supports with self-healing capabilities and its preparation method. Background Technology

[0002] High-water-content hydraulic fluid, formulated with concentrated concentrate, is the transmission medium and lifeblood of hydraulic supports. Currently, high-water-content hydraulic fluid is prepared by mixing mine water and bottled concentrated concentrate in an underground pump box. However, mine water sources are diverse, and in some areas, the water quality is poor with high conductivity, especially when the mine water contains high concentrations of Cl. - and SO4 2- In acidic environments, corrosion can easily occur inside hydraulic support jacks and metal hydraulic pipes. Prolonged exposure can also cause pitting corrosion on the inner wall of the jacks, increase gaps in seals, lead to leaks and pressure relief, clog pipes and filters, and increase the risk of high-pressure pipe bursts causing injury. Therefore, improving the corrosion resistance of concentrated fluid used in hydraulic supports is of paramount importance for mine safety.

[0003] Currently, the most effective and direct method to solve the corrosion problem of hydraulic supports is to add corrosion inhibitors to the concentrate. Through a film-forming protective mechanism, this prevents the metal substrate from contacting the corrosive medium, achieving an anti-corrosion effect. Commonly used corrosion inhibitors in concentrates are divided into inorganic and organic corrosion inhibitors. Commonly used inorganic corrosion inhibitors mainly include molybdates, nitrites, nitrates, and phosphates. However, molybdates are expensive and need to be compounded with other corrosion inhibitors to improve cost-effectiveness; nitrites are limited in application due to their carcinogenicity; and long-term use of phosphates can lead to phosphorus pollution. Organic corrosion inhibitors include organic amine corrosion inhibitors (such as cyclohexylamine and morpholine derivatives) and carboxylic acid organic corrosion inhibitors (such as lauric acid and sebacic acid). However, organic amine corrosion inhibitors can irritate the skin upon direct contact; while carboxylic acid organic corrosion inhibitors, although non-toxic and harmless, have generally weak corrosion inhibition performance, limiting their large-scale application. More seriously, the actual working environment of hydraulic supports is complex and harsh, with multiple factors such as high temperature, humidity, corrosion from corrosive media, abrasion, and impact, which can easily lead to micro-damage to the supports. These subtle micro-damages, if not repaired in time, will gradually spread and expand, causing cracks. The passivation film formed by corrosion inhibitor molecules on the metal substrate will be destroyed, making the corrosion resistance of the hydraulic support very limited and unable to provide long-term corrosion protection. Especially in practical applications, due to the dual constraints of detection and repair costs, micro-damage is difficult to repair in a timely and effective manner, thus greatly increasing the risk of corrosion to the metal substrate.

[0004] Furthermore, with increasing environmental awareness and stricter environmental monitoring, the requirements for the discharge of high-water-content hydraulic fluid from coal mines into the environment are becoming increasingly stringent. Direct discharge of high-water-content hydraulic fluid will lead to a continuous increase in the organic matter content of mine water, posing a serious threat to the aquatic environment. Therefore, in the face of these challenges, developing environmentally friendly, self-healing concentrated fluid for hydraulic supports has become an urgent problem to be solved in the field of mining materials. On the one hand, it overcomes the defects of traditional corrosion inhibitors, which are toxic, harmful, and pollute the ecological environment; on the other hand, it promotes the sustainable release of corrosion inhibitors through stimulation response, achieving the self-healing function of micro-damaged areas in hydraulic supports. Summary of the Invention

[0005] This invention aims to at least partially solve one of the technical problems in related technologies. To this end, embodiments of this invention propose an environmentally friendly concentrate for hydraulic supports with self-healing capabilities and a method for its preparation.

[0006] One embodiment of the present invention proposes an environmentally friendly hydraulic support concentrate with self-healing capability, comprising the following components by mass percentage: 5%–10% lubricant, 8%–18% self-healing corrosion inhibitor, 4%–8% emulsifier, 1%–3% water softener, 0.05%–0.08% defoamer, with the balance being water.

[0007] In some embodiments, the self-healing corrosion inhibitor is an inclusion complex β-cyclodextrin / bicycloimidazoline sebacate synthesized by self-assembly using β-cyclodextrin as a carrier and sebacate as a core material.

[0008] In some embodiments, the self-healing corrosion inhibitor is prepared by a method comprising the following steps:

[0009] S1, sebacic acid was mixed with N-(2-hydroxyethyl)ethylenediamine, and then xylene was added. The reaction was first carried out with acylation, followed by cyclization. After the reaction was completed, xylene was evaporated off by rotary evaporation, and the reaction product was washed with tetrahydrofuran to obtain sebacic acid bicyclic imidazoline.

[0010] S2, β-cyclodextrin is dissolved in water to obtain an aqueous solution of β-cyclodextrin; the dicycloimidazoline sebacate is dissolved in methanol to obtain a methanol solution of dicycloimidazoline sebacate; then the aqueous solution of β-cyclodextrin and the methanol solution of dicycloimidazoline sebacate are mixed, heated and stirred, then allowed to stand at low temperature, and finally centrifuged and vacuum dried to obtain the β-cyclodextrin / dicycloimidazoline sebacate inclusion complex, which is the self-healing corrosion inhibitor.

[0011] Further, in step S1, the molar ratio of sebacic acid to N-(2-hydroxyethyl)ethylenediamine is (1-3):(2-5);

[0012] And / or, the acylation reaction is carried out at a temperature of 120–150°C for a reaction time of 2–5 h;

[0013] And / or, the cyclization reaction is carried out at a temperature of 170–190°C for 2–4 hours.

[0014] Further, in step S2, the concentration of the β-cyclodextrin aqueous solution is 17.8–18.8 g / L, and the concentration of the sebacic acid bicycloimidazoline methanol solution is 3.2–6.5 g / L;

[0015] And / or, the heating and stirring temperature is 50-70°C, and the time is 2-5 hours;

[0016] And / or, the temperature for the low-temperature settling is -10 to 0°C, and the settling time is 20 to 40 hours;

[0017] And / or, the centrifugation speed is 6000-8000 rpm, and the centrifugation time is 10-30 min;

[0018] And / or, the vacuum drying temperature is 35–60°C, and the drying time is 8–20 h.

[0019] In some embodiments, the lubricant is cerium-doped graphene oxide-modified triethanolamine oleate, which is prepared by a method comprising the following steps:

[0020] a. Dissolve cerium chloride in ethanol, then add ethylenediaminetetraacetic acid, ammonium chloride and urea in sequence, heat in a water bath and stir to obtain a mixture; then adjust the pH of the mixture to 4-5 with nitric acid to obtain the dopant;

[0021] b. Immerse graphene oxide in N,N-dimethylformamide solution, then add the dopant, and disperse by ultrasonication to obtain a dispersion of cerium-doped graphene oxide; then centrifuge, wash and dry the dispersion to obtain cerium-doped graphene oxide.

[0022] c. The cerium-doped graphene oxide is added to an N,N-dimethylformamide solution and ultrasonically dispersed. Then, triethanolamine is added and heated to react, followed by oleic acid and a gradient high-temperature reaction until no water is generated, thus obtaining cerium-doped graphene oxide modified triethanolamine oleate, which is the lubricant.

[0023] Further, in step a, the mixture contains 96%–98% ethanol by mass, 0.5%–1.0% cerium chloride by mass, 0.3%–0.8% ethylenediaminetetraacetic acid by mass, 0.4%–1.0% ammonium chloride by mass, and 0.8%–1.2% urea by mass; the water bath heating temperature is 70–85°C, and the stirring and mixing time is 20–40 min.

[0024] And / or, in step b, the mass ratio of the graphene oxide to the dopant is (10-15):(3-8); the ultrasonic dispersion power is 100-150W, and the dispersion time is 3-5h; the centrifugation speed is 6000-8000rpm, and the centrifugation time is 15-30min; the drying temperature is 50-70℃, and the drying time is 24-48h.

[0025] And / or, in step c, the mass ratio of the cerium-doped graphene oxide to the triethanolamine and the oleic acid is (0.5-1.5):(65-75):(30-40); the reaction temperature of the heating reaction is 100-120℃, and the reaction time is 2-4h; the reaction process of the gradient high-temperature reaction is as follows: first, hold at 120-125℃ for 20-40min, then raise the temperature to 130-150℃ and continue the reaction until no water is generated.

[0026] In some embodiments, the emulsifier includes at least one of fatty alcohol polyoxyethylene ether, sodium petroleum sulfonate, and terephthalic acid oil;

[0027] And / or, the water softener includes at least one of ethylenediaminetetraacetic acid, disodium ethylenediaminetetraacetic acid, and sodium hypotriacetate;

[0028] And / or, the defoamer includes at least one of emulsified silicone oil, dimethyl silicone oil, and polyoxyethylene polyoxypropylene pentaerythritol ether.

[0029] Another aspect of this invention provides a method for preparing the above-mentioned self-healing, environmentally friendly hydraulic support concentrate, comprising the following steps:

[0030] (1) Add water softener to water to obtain water softener solution;

[0031] (2) Add lubricant, emulsifier and self-healing corrosion inhibitor to the water softener solution, stir at a constant temperature, and then add defoamer after the mixture has cooled to room temperature and mix evenly to obtain the environmentally friendly hydraulic support concentrate with self-healing ability.

[0032] In some embodiments, the temperature of the constant-temperature stirring is 40–60°C, and the stirring time is 1–3 hours.

[0033] The advantages and beneficial effects of the embodiments of the present invention are as follows:

[0034] (1) In this embodiment of the invention, a green corrosion inhibitor with self-healing function is synthesized by using bio-based β-cyclodextrin as a carrier and sebacic acid bicyclic imidazoline as a core material. When the hydraulic support is subjected to external force during operation, the carrier of the self-healing corrosion inhibitor breaks, releasing the core material inside. It gathers at the exposed surface at the damaged part of the substrate and fills the gap. Through physical adsorption and coordination, a corrosion-inhibiting passivation film is formed, which shields the corrosion medium from erosion and realizes the self-repair of the metal damage, thereby achieving long-term anti-corrosion effect and extending the service life of the equipment.

[0035] (2) In this embodiment of the invention, cerium-doped graphene oxide modified triethanolamine oleate is used as a lubricant, which can not only improve the lubricity and stability of the obtained concentrate; at the same time, the layered graphene oxide can serve as a film-forming material for substrate corrosion protection, with excellent barrier properties, and plays a synergistic anti-corrosion role with the self-healing corrosion inhibitor, further improving the corrosion resistance of the obtained concentrate; in addition, the hydroxyl groups of β-cyclodextrin in the self-healing corrosion inhibitor and the carboxyl groups of graphene oxide in the lubricant have a complexing effect on calcium and magnesium ions in water, which can reduce the sensitivity of the concentrate to hard water, reduce the amount of water softener used, and thus effectively reduce the COD value of the concentrate.

[0036] (3) The preparation process of the concentrate in the embodiments of the present invention is simple, reliable, easy to operate, mild in reaction conditions, low in energy consumption, and the concentrate has comprehensive excellent performance in terms of rust prevention, corrosion prevention, lubrication and environmental protection. Attached Figure Description

[0037] Figure 1 This is a scanning electron microscope image of β-cyclodextrin in Example 1 of the present invention.

[0038] Figure 2 This is a scanning electron microscope image of the β-cyclodextrin / sebacic acid bicyclic imidazoline inclusion product in Example 1 of the present invention.

[0039] Figure 3 The concentrated solution prepared in Example 1 of this invention is based on the local electrochemical impedance measurement results of the artificial defect region in the micro-area electrochemical test sample (self-healing time = 0h).

[0040] Figure 4 The concentrated solution prepared in Example 1 of this invention is based on the local electrochemical impedance measurement results of the artificial defect region in the micro-area electrochemical test sample (self-healing time = 24h). Detailed Implementation

[0041] The embodiments of the present invention are described in detail below. These embodiments are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0042] In this document, when values ​​are described as ranges, it should be understood that such disclosure includes disclosure of all possible subranges within that range, as well as the specific numerical values ​​falling within that range, regardless of whether the specific numerical value or specific subrange is explicitly specified.

[0043] In this article, the words “contain” and “include” and their various variations mean that other elements or wholes may be included but not specifically described.

[0044] In this article, the term "and / or" is merely a description of the relationship between related objects, indicating that there can be three kinds of relationships. For example, A and / or B can represent three cases: A exists alone, A and B exist simultaneously, and B exists alone.

[0045] One embodiment of the present invention proposes an environmentally friendly hydraulic support concentrate with self-healing capability, comprising the following components by mass percentage: 5%–10% lubricant, 8%–18% self-healing corrosion inhibitor, 4%–8% emulsifier, 1%–3% water softener, 0.05%–0.08% defoamer, with the balance being water.

[0046] In some embodiments, the self-healing corrosion inhibitor is an inclusion complex β-cyclodextrin / dicycloimidazoline sebacate (β-CD / GM) synthesized by self-assembly using β-cyclodextrin (β-CD) as a carrier and dicycloimidazoline sebacate (GM) as a core material.

[0047] In some embodiments, the self-healing corrosion inhibitor is prepared by a method comprising the following steps:

[0048] S1, sebacic acid was mixed with N-(2-hydroxyethyl)ethylenediamine, and then xylene was added. The reaction was first carried out with acylation, followed by cyclization. After the reaction was completed, xylene was evaporated off by rotary evaporation, and the reaction product was washed with tetrahydrofuran to obtain sebacic acid bicyclic imidazoline.

[0049] S2, β-cyclodextrin is dissolved in water to obtain an aqueous solution of β-cyclodextrin; the dicycloimidazoline sebacate is dissolved in methanol to obtain a methanol solution of dicycloimidazoline sebacate; then the aqueous solution of β-cyclodextrin and the methanol solution of dicycloimidazoline sebacate are mixed, heated and stirred, then allowed to stand at low temperature, and finally centrifuged and vacuum dried to obtain the β-cyclodextrin / dicycloimidazoline sebacate inclusion complex, which is the self-healing corrosion inhibitor.

[0050] β-CD possesses non-toxic, harmless, non-irritating, and readily biodegradable properties. Its unique molecular structure makes it an ideal candidate for preparing self-healing material carriers. The inner wall of the β-CD molecule is hydrophobic, while the outer side, composed of hydroxyl groups, is hydrophilic. Therefore, utilizing the amphiphilic nature and cavity structure of the β-CD molecule, guest molecules can be encapsulated through non-covalent interactions to form stable inclusion compounds. Meanwhile, the GM molecule contains a five-membered nitrogen heterocyclic structure. The lone pair electrons on the nitrogen atom and the empty orbitals of the iron atom can form coordinate bonds, thereby forming an effective adsorption film on the metal surface, which can then prevent direct contact between the corrosive medium and the metal substrate. Based on this, this invention employs cyclodextrin inclusion technology, using β-CD as the carrier and GM as the core material, to synthesize a green corrosion inhibitor with self-healing function through self-assembly. When the hydraulic support suffers micro-damage, the β-CD in this self-healing corrosion inhibitor can mechanically release GM at the damaged site, thereby forming a passivation layer on the exposed metal surface, achieving self-repair of the micro-damaged area, thus achieving long-term corrosion protection and extending the service life of the equipment. This self-healing corrosion inhibitor eliminates the use of nitrite in traditional corrosion inhibitor systems. Instead, it uses β-CD, which is more biodegradable, as a carrier, making it safe, healthy, and environmentally friendly.

[0051] Further, in step S1, the molar ratio of sebacic acid to N-(2-hydroxyethyl)ethylenediamine is (1-3):(2-5);

[0052] And / or, the reaction temperature of the acylation reaction is 120-150°C, and the reaction time is 2-5 hours. The inventors have found through research that if the reaction temperature of the acylation reaction is too high, it will not only easily cause oxidation of the raw materials or the formation of by-products, but also accelerate the evaporation of the solvent, thereby reducing the concentration of reactants in the system, inhibiting the forward progress of the reversible reaction, and thus affecting the reaction yield. Therefore, in the embodiments of the present invention, the reaction temperature of the acylation reaction is controlled within the range of 120-150°C.

[0053] And / or, the cyclization reaction is carried out at a temperature of 170–190°C for 2–4 hours.

[0054] It should be noted that in step S1, when the cyclization reaction is carried out, the reaction endpoint is reached when the amount of water discharged no longer increases, and then the xylene solvent can be evaporated by rotary evaporator.

[0055] Further, in step S2, the concentration of the β-cyclodextrin aqueous solution is 17.8–18.8 g / L, and the concentration of the sebacic acid bicycloimidazoline methanol solution is 3.2–6.5 g / L. During the self-assembly synthesis of the inclusion complex, if the concentration of the carrier β-CD is too high and the GM concentration is insufficient, the corrosion and rust prevention properties of the resulting concentrate will not easily meet the standard requirements. Conversely, if the core material GM concentration is too high and the β-CD is insufficient, more unincluded GM will appear in the resulting concentrate system, thus making it difficult for the stability of the concentrate to meet the standard requirements. Therefore, in this embodiment of the invention, the concentrations of β-CD and GM are controlled within the above-mentioned ranges.

[0056] And / or, the heating and stirring temperature is 50-70°C, and the time is 2-5 hours; by heating and stirring, the methanol solvent can be evaporated, β-CD and GM can be fully contacted, which is beneficial to the self-assembly synthesis reaction.

[0057] And / or, the temperature of the low-temperature settling is -10 to 0°C, and the settling time is 20 to 40 hours; lowering the temperature can reduce the solubility of the inclusion complex, but if the temperature is too low, the aqueous solution of the inclusion complex will easily freeze. Therefore, it is advantageous to control the temperature of the low-temperature settling in the range of -10 to 0°C in the embodiments of this application.

[0058] And / or, the centrifugation speed is 6000-8000 rpm and the centrifugation time is 10-30 min; if the centrifugation speed is too low, the inclusion complex cannot be completely separated; but if the centrifugation speed is too high, the microstructure of the inclusion complex is easily destroyed.

[0059] And / or, the vacuum drying temperature is 35–60°C, and the drying time is 8–20 h.

[0060] In some embodiments, the lubricant is cerium-doped graphene oxide-modified triethanolamine oleate, which is prepared by a method comprising the following steps:

[0061] a. Dissolve cerium chloride in ethanol, then add ethylenediaminetetraacetic acid, ammonium chloride and urea in sequence, heat in a water bath and stir to obtain a mixture; then adjust the pH of the mixture to 4-5 with nitric acid to obtain the dopant;

[0062] b. Immerse graphene oxide in N,N-dimethylformamide solution, then add the dopant, and disperse by ultrasonication to obtain a dispersion of cerium-doped graphene oxide; then centrifuge, wash and dry the dispersion to obtain cerium-doped graphene oxide.

[0063] c. The cerium-doped graphene oxide is added to an N,N-dimethylformamide solution and ultrasonically dispersed. Then, triethanolamine is added and heated to react, followed by oleic acid and a gradient high-temperature reaction until no water is generated, thus obtaining cerium-doped graphene oxide modified triethanolamine oleate, which is the lubricant.

[0064] The preparation of the aforementioned lubricant is based on the inventors' discoveries and understanding of the following facts and problems: Triethanolamine oleate, as a traditional concentrated lubricant, exhibits outstanding lubricating performance. However, in high-hardness water environments, triethanolamine oleate readily reacts with calcium and magnesium ions to form insoluble soap deposits (such as calcium oleate), which not only reduces its emulsifying and dispersing ability but also leads to lubricant stratification, precipitation, and even equipment blockage. Graphene oxide, composed of multiple layers of carbon atoms, can form a stable π-π conjugated structure, enabling it to form an ultra-thin protective film at the friction interface, thereby significantly reducing the coefficient of friction and improving lubrication performance. Furthermore, the carboxyl and hydroxyl groups on the outer edge of graphene oxide can complex with calcium and magnesium ions in water, enhancing its tolerance to hard water and thus solving the valve blockage problem caused by soap deposits in traditional lubricants. However, unmodified graphene oxide is prone to aggregation, severely affecting its dispersibility.

[0065] Based on this, the embodiments of the present invention use cerium to dope and modify graphene oxide. On the one hand, in the valence electron configuration of cerium, since its 4f electron layer cannot completely cover its atomic nucleus, cerium carries a strong effective charge and can have a strong affinity for non-metallic elements such as H, O, and N. Graphene oxide contains a large number of oxygen-containing functional groups. One oxygen atom can provide an empty 2p orbital to accept a coordinating electron and form a coordinate bond with cerium, significantly reducing the surface energy of oxygen atoms in graphene oxide. This also reduces the aggregation of graphene oxide by decreasing π-π interactions, thus improving its dispersibility. This, in turn, mitigates the problem of triethanolamine oleate easily precipitating soap in hard water environments, resulting in a significant improvement in the lubrication and stability of the resulting concentrate. Furthermore, layered graphene oxide can serve as a film-forming material for corrosion protection of metal substrates, exhibiting excellent anti-corrosion properties and synergistically protecting against corrosion with self-healing corrosion inhibitors. In addition, the hydroxyl groups of β-cyclodextrin and the carboxyl and hydroxyl groups of graphene oxide have a complexing effect on calcium and magnesium ions in water, reducing the sensitivity of the concentrate to hard water, decreasing the amount of water softener needed, and effectively lowering the COD value of the concentrate.

[0066] Further, in step a, the mixture contains 96%–98% ethanol by mass, 0.5%–1.0% cerium chloride by mass, 0.3%–0.8% ethylenediaminetetraacetic acid by mass, 0.4%–1.0% ammonium chloride by mass, and 0.8%–1.2% urea by mass; the water bath heating temperature is 70–85°C, and the stirring and mixing time is 20–40 min.

[0067] And / or, in step b, the mass ratio of graphene oxide to the dopant is (10-15):(3-8). A small amount of cerium-doped graphene oxide can improve the lubrication performance and stability of the concentrate, while an excessive amount of cerium-doped graphene oxide will affect the appearance of the concentrate; the ultrasonic dispersion power is 100-150W, and the dispersion time is 3-5h; the centrifugation speed is 6000-8000rpm, and the centrifugation time is 15-30min; the drying temperature is 50-70℃, and the drying time is 24-48h.

[0068] And / or, in step c, the mass ratio of the cerium-doped graphene oxide to the triethanolamine and the oleic acid is (0.5–1.5):(65–75):(30–40); the reaction temperature of the heating reaction is 100–120°C, and the reaction time is 2–4 hours; the reaction process of the gradient high-temperature reaction is as follows: first, the initial esterification is completed by holding at 120–125°C for 20–40 minutes, and then the temperature is increased to 130–150°C for continuous reaction until no water is generated. This process is a dehydration condensation process, which requires high temperature to accelerate esterification. When the reaction temperature is too low, the reaction rate will decrease significantly, but if the reaction temperature is too high, side reactions (such as oxidation or decomposition) may be triggered, the product color will darken and the stability will decrease.

[0069] In some embodiments, the emulsifier includes at least one of fatty alcohol polyoxyethylene ether, sodium petroleum sulfonate, and terephthalic acid oil;

[0070] And / or, the water softener includes at least one of ethylenediaminetetraacetic acid (EDTA), disodium ethylenediaminetetraacetate (EDTA-2Na), and sodium triacetate (NTA-3Na);

[0071] And / or, the defoamer includes at least one of emulsified silicone oil, dimethyl silicone oil, and polyoxyethylene polyoxypropylene pentaerythritol ether.

[0072] Another aspect of this invention provides a method for preparing the above-mentioned self-healing, environmentally friendly hydraulic support concentrate, comprising the following steps:

[0073] (1) Add water softener to water to obtain water softener solution;

[0074] (2) Add lubricant, emulsifier and self-healing corrosion inhibitor to the water softener solution, stir at a constant temperature, and then add defoamer after the mixture has cooled to room temperature and mix evenly to obtain the environmentally friendly hydraulic support concentrate with self-healing ability.

[0075] In some embodiments, the temperature of the constant-temperature stirring is 40–60°C, and the stirring time is 1–3 hours.

[0076] The following are non-limiting embodiments and comparative examples of the present invention. It should be noted that the schemes in the comparative examples are not prior art, but are only set up for comparison with the schemes in the embodiments, and are not intended to limit the present invention. Unless otherwise stated, all raw materials used in the embodiments and comparative examples are conventional commercially available products, or can be prepared by known methods.

[0077] Example 1

[0078] This embodiment provides an environmentally friendly hydraulic support concentrate with self-healing capabilities. The concentrate comprises the following components by mass percentage: 7% lubricant, 12% self-healing corrosion inhibitor, 4% emulsifier, 1% water softener, 0.05% defoamer, and the balance being water.

[0079] In this embodiment, the lubricant is cerium-doped graphene oxide-modified triethanolamine oleate, prepared by a method comprising the following steps:

[0080] a. Dissolve 0.574g of cerium chloride in 100mL of ethanol, then add 0.41g of ethylenediaminetetraacetic acid, 0.42g of ammonium chloride and 0.82g of urea in sequence. Heat in a water bath to 80℃ and stir for 30min to obtain a mixture. Then adjust the pH of the mixture to 5 with nitric acid to obtain the dopant.

[0081] b. Immerse 10 mg of graphene oxide in 10 mL of N,N-dimethylformamide solution, then add 6 mg of dopant, and disperse using ultrasound at 100 W for 3 h to obtain a dispersion of cerium-doped graphene oxide; then centrifuge the dispersion at 6000 rpm for 16 min, wash it several times with hot anhydrous ethanol and deionized water, and finally dry it in a vacuum environment at 60 °C for 24 h to obtain cerium-doped graphene oxide.

[0082] c. Add 1.0g of cerium-doped graphene oxide to 10mL of N,N-dimethylformamide solution and sonicate for 20min to disperse it evenly. Then add 66.8g of triethanolamine and heat at 110℃ for 3h. Then add 34.5g of oleic acid and keep at 120℃ for 30min to complete the initial esterification. Then raise the temperature to 140℃ to continue the high-temperature reaction until no water is generated. The cerium-doped graphene oxide modified triethanolamine oleate can be obtained, which is the lubricant.

[0083] In this embodiment, the self-healing corrosion inhibitor is an inclusion complex β-cyclodextrin / dicycloimidazoline sebacic acid (β-CD / GM) synthesized through self-assembly using β-cyclodextrin (β-CD) as the carrier and sebacic acid bicyclic imidazoline (GM) as the core material. The specific preparation process includes the following steps:

[0084] S1, a mixture of sebacic acid and N-(2-hydroxyethyl)ethylenediamine in a molar ratio of 2:3 was added to a three-necked flask, followed by 80 mL of xylene water-carrying agent. After assembling the flask with a stirrer, condenser, thermometer, and water separator, the mixture was heated. The acylation reaction was first carried out by reflux at 130 °C for 3 h, followed by the cyclization reaction by reflux at 180 °C for 3 h. The reaction endpoint was reached when the amount of water produced no longer increased. After the reaction was completed, the xylene solvent was removed by rotary evaporation, and the reaction product was washed 5 times with tetrahydrofuran to obtain GM.

[0085] S2, 1.88 g of β-CD was dissolved in 100 mL of deionized water (25℃±1) to prepare a saturated aqueous solution of β-CD; simultaneously, 0.46 g of GM was dissolved in 100 mL of methanol (25℃±1) to obtain a GM methanol solution; then the saturated aqueous solution of β-CD and the GM methanol solution were stirred and mixed at 65℃ for 4 h to ensure full contact. During the mixing process, the hydrophobic guest GM molecules entered the hydrophobic cavity structure of β-CD to form inclusion complexes; then the mixture was allowed to stand at -10℃ for 30 h; then the mixture was centrifuged at 8000 rpm for 20 min; finally, it was placed in a vacuum drying oven and dried at 55℃ for 15 h to obtain a green self-healing corrosion inhibitor β-CD / GM with β-CD as the shell wall and GM molecules encapsulated.

[0086] In this embodiment, the emulsifier is fatty alcohol polyoxyethylene ether.

[0087] In this embodiment, the water softener is ethylenediaminetetraacetic acid (EDTA).

[0088] In this embodiment, the defoamer is emulsified silicone oil.

[0089] Figure 1 and Figure 2The figures show the microstructures of β-CD before and after inclusion, specifically the inclusion product β-CD / GM. As can be seen, before inclusion, β-CD exhibits a regular layered crystal structure. After inclusion, the microstructure changes significantly. Compared to pure β-CD, the degree of structural order decreases, forming a film-like substance attached to the matrix surface, tending towards an amorphous structure. This is due to the increased steric hindrance and intermolecular compression of the inclusion product, leading to a greater tendency to form irregular structures when clustered or stacked. The change in microstructure confirms the formation of the inclusion product.

[0090] The self-healing performance of the concentrate prepared in this embodiment was tested. When the self-healing time was 0 h and 24 h, the local electrochemical impedance spectroscopy results of the artificial defect region in the micro-area electrochemical test sample were as follows: Figure 3 and Figure 4 As shown. Figure 3 The blue recessed area represents an artificial scratch defect. When the carbon steel surface suffers micro-damage, the passivation film is damaged, and the resistance of the exposed metal surface decreases; however, after 24 hours of self-healing corrosion inhibitor treatment... Figure 4 The core material GM, which is encapsulated in the β-CD carrier, fills the gaps in the substrate, repairs the defects in the sample, and restores the passivation film on the metal surface. Therefore, the impedance of the metal surface is restored to the state before artificial scratches, and the 3D image shows that the depression is filled.

[0091] This embodiment also provides a method for preparing the above-mentioned self-healing environmentally friendly hydraulic support concentrate, including the following steps:

[0092] (1) Add water softener to water to obtain water softener solution;

[0093] (2) Add lubricant, emulsifier and self-healing corrosion inhibitor to the water softener solution, stir for 2 hours at a constant temperature of 60°C, and then add defoamer after the mixture has cooled to room temperature and mix evenly to obtain an environmentally friendly hydraulic support concentrate with self-healing ability.

[0094] Example 2

[0095] This embodiment is basically the same as Embodiment 1, except that the mass percentage of the self-healing corrosion inhibitor in the concentrate of this embodiment is 8%.

[0096] Example 3

[0097] This embodiment is basically the same as Embodiment 1, except that the mass percentage of the self-healing corrosion inhibitor in the concentrate of this embodiment is 18%.

[0098] Example 4

[0099] This embodiment is basically the same as that of embodiment 1, except that in step S2 of preparing the self-healing corrosion inhibitor in the concentrate of this embodiment, 0.32g of sebacic acid bicyclic imidazoline (GM) is dissolved in 100mL of methanol.

[0100] Example 5

[0101] This embodiment is basically the same as that of embodiment 1, except that in step S2 of preparing the self-healing corrosion inhibitor in the concentrate of this embodiment, 0.65g of sebacic acid bicyclic imidazoline (GM) is dissolved in 100mL of methanol.

[0102] Example 6

[0103] This embodiment is basically the same as Embodiment 1, except that in step c of the lubricant preparation in the concentrate of this embodiment, 0.5g of cerium-doped graphene oxide is added to 10mL of N,N-dimethylformamide solution.

[0104] Example 7

[0105] This embodiment is basically the same as Embodiment 1, except that in step c of the lubricant preparation in the concentrated solution of this embodiment, 1.5g of cerium-doped graphene oxide is added to 10mL of N,N-dimethylformamide solution.

[0106] Comparative Example 1

[0107] This comparative example is basically the same as Example 1, except that the corrosion inhibitor in the concentrated solution of this comparative example is a mixture of nitrite, sodium benzoate and benzotriazole in a mass ratio of 15:4:3, and the water softener has a mass percentage of 4%. Comparative Example 2

[0108] This comparative example is basically the same as Example 1, except that the corrosion inhibitor in the concentrated solution of this comparative example is only sebacic acid bicyclic imidazoline (GM), without the coating of carrier β-cyclodextrin (β-CD).

[0109] Comparative Example 3

[0110] This comparative example is basically the same as Example 1, except that the corrosion inhibitor in the concentrate of this comparative example is only β-cyclodextrin (β-CD), and there is no core material of sebacic acid bicyclic imidazoline (GM).

[0111] Comparative Example 4

[0112] This comparative example is basically the same as Example 1, except that the lubricant in the concentrate of this comparative example is not doped with cerium, that is, graphene oxide-triethanolamine oleate.

[0113] Comparative Example 5

[0114] This comparative example is basically the same as Example 1, except that the lubricant in the concentrate of this comparative example has not been modified with cerium-doped graphene oxide, that is, the lubricant is triethanolamine oleate, and the mass percentage of the water softener is 4%.

[0115] The self-healing performance of the concentrated solutions prepared in the above embodiments and comparative examples was tested: a micro-area electrochemical testing platform with a three-electrode system and a micron-sized ultramicro probe was used to detect the local electrochemical signals of the metal material and test the self-healing time. The specific operation method was as follows: a carbon steel disc with a diameter of 35 mm was prepared and immersed in the concentrated solution for 24 hours, allowing the self-healing corrosion inhibitor to form a stable passivation film on the metal surface; then the sample was removed, and a scratch with a diameter of 500 μm and a depth of 300 μm was artificially created. Subsequently, impedance (LEIS) tests were performed every two hours. The LEIS at the defect gradually increased. When the LEIS recovered to 90% of the current signal before the damage, this time was recorded as the self-healing time. The self-healing times of each concentrated solution are shown in Table 1.

[0116] High-water-content hydraulic fluids (with a mass fraction of 4%) were prepared using the concentrates obtained in the above examples and comparative examples, respectively. Their corrosion resistance, rust prevention, lubrication, and stability were determined according to the test methods in MT76-2011 "Emulsified oils, concentrates and high-water-content hydraulic fluids for hydraulic supports". The results are shown in Table 1.

[0117] Table 1

[0118]

[0119]

[0120] As can be seen from Table 1, the concentrate in the embodiments of the present invention clearly possesses self-healing function due to the addition of a self-healing corrosion inhibitor. When microscopic damage occurs on the metal surface, the β-CD carrier releases the internal corrosion inhibitor GM under the action of external force to fill the gaps and acts on the exposed metal substrate to form a slow-release protective film, thereby achieving self-repair at the damaged area. In contrast, the concentrates in Comparative Examples 1-3 do not possess self-healing ability because their concentrate systems do not contain a self-healing corrosion inhibitor with a complete core-shell structure. Furthermore, the self-healing time of Comparative Example 5 is longer than that of Example 1 because the triethanolamine oleate in Comparative Example 5 does not have cerium-doped graphene oxide grafted onto it, resulting in the self-healing corrosion inhibitor and lubricant failing to exert a synergistic anti-corrosion effect.

[0121] As shown in Table 1, the high-water-content hydraulic fluid prepared using the concentrate from Comparative Example 3 did not meet the standard requirements for corrosion resistance and rust prevention. This is because the concentrate system did not contain sebacic acid bicyclic imidazoline (GM), which has a corrosion-inhibiting effect, leading to a decrease in the corrosion-inhibiting performance of the resulting concentrate. Furthermore, the concentrate of this embodiment shows a significant improvement in lubrication performance compared to Comparative Examples 4-5. This is mainly because the embodiment grafted cerium-doped graphene oxide onto triethanolamine oleate. The layered structure of graphene oxide can form a stable π-π structure, forming a protective film at the friction interface, reducing the coefficient of friction, and thus effectively improving lubrication performance. The stability of Comparative Example 2 did not meet the standard requirements because GM is insoluble in water, causing the sample to separate and precipitate. The stability of Comparative Example 4 did not meet the standard requirements because the graphene oxide did not contain rare earth elements, and graphene oxide is prone to aggregation, thus reducing the stability of the system.

[0122] Furthermore, the COD value of the samples was determined according to HJ828-2017 "Determination of Chemical Oxygen Demand in Water - Potassium Dichromate Method". The experiment revealed that the COD values ​​of Comparative Examples 1, 2, and 5 were higher than those of other samples. This was because the concentrate system did not contain the self-healing corrosion inhibitor β-CD / GM or cerium-doped graphene oxide triethanolamine oleate. However, when the self-healing corrosion inhibitor and cerium-doped graphene oxide triethanolamine oleate were introduced into the concentrate raw materials, the hydroxyl groups of the β-CD molecules, as well as the carboxyl and hydroxyl groups of graphene oxide, could undergo complexation reactions with calcium and magnesium ions in the water. This enhanced the concentrate's tolerance to hard water, reduced the amount of other additives (such as water softeners and emulsifiers), and thus effectively lowered the COD value of the samples.

[0123] In this invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0124] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A self-healing, environmentally friendly hydraulic support concentrate, characterized in that, It includes the following components by weight percentage: lubricant 5%–10%, self-healing corrosion inhibitor 8%–18%, emulsifier 4%–8%, water softener 1%–3%, defoamer 0.05%–0.08%, with the balance being water.

2. The self-healing, environmentally friendly hydraulic support concentrate according to claim 1, characterized in that, The self-healing corrosion inhibitor is an inclusion compound β-cyclodextrin / bicycloimidazoline sebacate, synthesized through self-assembly using β-cyclodextrin as the carrier and sebacate as the core material.

3. The self-healing, environmentally friendly hydraulic support concentrate according to claim 2, characterized in that, The self-healing corrosion inhibitor is prepared by a method comprising the following steps: S1, sebacic acid was mixed with N-(2-hydroxyethyl)ethylenediamine, and then xylene was added. The reaction was first carried out with acylation, followed by cyclization. After the reaction was completed, xylene was evaporated off by rotary evaporation, and the reaction product was washed with tetrahydrofuran to obtain sebacic acid bicyclic imidazoline. S2, β-cyclodextrin is dissolved in water to obtain an aqueous solution of β-cyclodextrin; the dicycloimidazoline sebacate is dissolved in methanol to obtain a methanol solution of dicycloimidazoline sebacate; then the aqueous solution of β-cyclodextrin and the methanol solution of dicycloimidazoline sebacate are mixed, heated and stirred, then allowed to stand at low temperature, and finally centrifuged and vacuum dried to obtain the β-cyclodextrin / dicycloimidazoline sebacate inclusion complex, which is the self-healing corrosion inhibitor.

4. The self-healing, environmentally friendly hydraulic support concentrate according to claim 3, characterized in that, In step S1, the molar ratio of sebacic acid to N-(2-hydroxyethyl)ethylenediamine is (1-3):(2-5); And / or, the acylation reaction is carried out at a temperature of 120–150°C for a reaction time of 2–5 h; And / or, the cyclization reaction is carried out at a temperature of 170–190°C for 2–4 hours.

5. The self-healing, environmentally friendly hydraulic support concentrate according to claim 3, characterized in that, In step S2, the concentration of the β-cyclodextrin aqueous solution is 17.8–18.8 g / L, and the concentration of the sebacic acid bicycloimidazoline methanol solution is 3.2–6.5 g / L. And / or, the heating and stirring temperature is 50-70°C, and the time is 2-5 hours; And / or, the temperature for the low-temperature settling is -10 to 0°C, and the settling time is 20 to 40 hours; And / or, the centrifugation speed is 6000-8000 rpm, and the centrifugation time is 10-30 min; And / or, the vacuum drying temperature is 35–60°C, and the drying time is 8–20 h.

6. The self-healing, environmentally friendly hydraulic support concentrate according to claim 1, characterized in that, The lubricant is cerium-doped graphene oxide-modified triethanolamine oleate, which is prepared by a method comprising the following steps: a. Dissolve cerium chloride in ethanol, then add ethylenediaminetetraacetic acid, ammonium chloride and urea in sequence, heat in a water bath and stir to obtain a mixture; then adjust the pH of the mixture to 4-5 with nitric acid to obtain the dopant; b. Immerse graphene oxide in N,N-dimethylformamide solution, then add the dopant, and disperse by ultrasonication to obtain a dispersion of cerium-doped graphene oxide; then centrifuge, wash and dry the dispersion to obtain cerium-doped graphene oxide. c. The cerium-doped graphene oxide is added to an N,N-dimethylformamide solution and ultrasonically dispersed. Then, triethanolamine is added and heated to react, followed by oleic acid and a gradient high-temperature reaction until no water is generated, thus obtaining cerium-doped graphene oxide modified triethanolamine oleate, which is the lubricant.

7. The self-healing, environmentally friendly hydraulic support concentrate according to claim 6, characterized in that, In step a, the mixture contains 96%–98% ethanol, 0.5%–1.0% cerium chloride, 0.3%–0.8% ethylenediaminetetraacetic acid, 0.4%–1.0% ammonium chloride, and 0.8%–1.2% urea; the water bath heating temperature is 70–85°C, and the stirring and mixing time is 20–40 minutes. And / or, in step b, the mass ratio of the graphene oxide to the dopant is (10-15):(3-8); the ultrasonic dispersion power is 100-150W, and the dispersion time is 3-5h; the centrifugation speed is 6000-8000rpm, and the centrifugation time is 15-30min; the drying temperature is 50-70℃, and the drying time is 24-48h. And / or, in step c, the mass ratio of the cerium-doped graphene oxide to the triethanolamine and the oleic acid is (0.5-1.5):(65-75):(30-40); the reaction temperature of the heating reaction is 100-120℃, and the reaction time is 2-4h; the reaction process of the gradient high-temperature reaction is as follows: first, hold at 120-125℃ for 20-40min, then raise the temperature to 130-150℃ and continue the reaction until no water is generated.

8. The self-healing, environmentally friendly hydraulic support concentrate according to claim 1, characterized in that, The emulsifier includes at least one of fatty alcohol polyoxyethylene ether, sodium petroleum sulfonate, and Taikoo oil; And / or, the water softener includes at least one of ethylenediaminetetraacetic acid, disodium ethylenediaminetetraacetic acid, and sodium hypotriacetate; And / or, the defoamer includes at least one of emulsified silicone oil, dimethyl silicone oil, and polyoxyethylene polyoxypropylene pentaerythritol ether.

9. A method for preparing a self-healing, environmentally friendly hydraulic support concentrate as described in any one of claims 1-8, characterized in that, Includes the following steps: (1) Add water softener to water to obtain water softener solution; (2) Add lubricant, emulsifier and self-healing corrosion inhibitor to the water softener solution, stir at a constant temperature, and then add defoamer after the mixture has cooled to room temperature and mix evenly to obtain the environmentally friendly hydraulic support concentrate with self-healing ability.

10. The method for preparing the self-healing, environmentally friendly hydraulic support concentrate according to claim 9, characterized in that, The temperature of the constant-temperature stirring is 40-60℃, and the stirring time is 1-3 hours.

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