A biodegradable natural plant-extracted emulsified oil for hydraulic support and its preparation method

Abstract

The present invention belongs to the technical field of oils for hydraulic supports and provides a biodegradable natural plant-extracted emulsified oil for hydraulic supports and a preparation method thereof. First, through multi-step chemical modification of palm oil, including epoxidation, boronation, phosphating, and block polymerization, the epoxidation reaction introduces epoxy groups, increasing the reactivity of the oil; the boronation and phosphating reactions further enhance the polarity of the oil and its ability to form a lubricating film; and through block polymerization with caprolactone, the stability and wear resistance of the lubricating film are enhanced. Second, through carboxymethylation of chitosan, the carboxyl groups in the carboxymethyl chitosan react with oxides on the metal surface to form a chemical passivation protective film; and the sulfonic acid groups in the sodium lignosulfonate bind to the metal surface through electrostatic adsorption, further forming a protective layer. The synergistic effect of the two forms a multi-layer dense protective film on the metal surface, significantly improving the anti-corrosion performance of the emulsified oil.

Description

Technical Field

[0001] The invention belongs to the technical field of oil for hydraulic supports and relates to a degradable natural plant-extracted emulsified oil for hydraulic supports and a preparation method thereof. Background Art

[0002] Hydraulic support emulsions, the primary working medium in coal mine hydraulic support systems, are a key factor influencing support performance. Traditional emulsions are primarily based on mineral oil, supplemented with additives such as emulsifiers, rust inhibitors, and antiwear agents. However, during use, these emulsions generate significant amounts of wastewater, which poses a significant environmental risk. Furthermore, the mineral oil and certain chemical additives contained in these emulsions are toxic and non-degradable, posing a threat not only to the ecological environment but also to human health. Compared to traditional mineral oil-based emulsions, vegetable oils offer the advantages of widespread availability, renewable availability, and high biodegradability. Furthermore, vegetable oils contain a high number of polar groups, providing excellent lubricity and antiwear properties. However, bio-based emulsions are susceptible to microbial contamination, and the byproducts produced by microbial decomposition can further exacerbate metal corrosion. Therefore, developing a biodegradable, natural plant-derived emulsion for hydraulic supports that combines excellent lubricity and corrosion resistance holds great promise. Summary of the Invention

[0003] In response to the shortcomings of the prior art, the present invention aims to provide a biodegradable natural plant-extracted emulsified oil for hydraulic supports and a preparation method thereof. Palm oil is subjected to epoxidation, boronization, phosphating, and block copolymerization to prepare polyester-blocked palm oil with excellent lubricity and chemical stability. Chitosan is alkalized under the action of sodium hydroxide and then reacted with chloroacetic acid to prepare carboxymethyl chitosan, whose carboxyl group has good water solubility and metal chelating ability. The carboxymethyl chitosan is compounded with sodium lignosulfonate, and the synergistic effect of the two is utilized to enhance the emulsion stability and the anti-corrosion protection ability of the metal surface, thereby meeting the needs of actual production.

[0004] To achieve this object, the present invention adopts the following technical solutions:

[0005] In a first aspect, the present invention provides a method for preparing a degradable natural plant-extracted emulsified oil for a hydraulic support, the preparation method comprising:

[0006] Step S1, mixing palm oil, hydrogen peroxide and formic acid, heating to a first temperature and stirring for reaction, washing the product after the reaction to obtain epoxidized palm oil, mixing the epoxidized palm oil with boric acid, heating to a second temperature, stirring and reacting thoroughly, cooling to room temperature after the reaction to obtain boronated palm oil, then mixing the boronated palm oil, triethyl phosphate and p-toluenesulfonic acid, heating to a third temperature and reacting thoroughly to obtain phosphated palm oil, then mixing the phosphated palm oil, caprolactone and tetrabutyl titanate, heating to a fourth temperature under a nitrogen atmosphere and reacting thoroughly, and rotary evaporating after the reaction to obtain polyester block palm oil;

[0007] Step S2, dispersing chitosan in an ethanol aqueous solution, stirring to swell the chitosan, adding a NaOH solution to the swollen chitosan solution and letting it stand to obtain an alkalized chitosan solution, adding a chloroacetic acid solution to the alkalized chitosan solution, heating to a first temperature in a water bath and stirring to react, filtering, washing, and vacuum drying after completion of the reaction to obtain carboxymethyl chitosan, and then uniformly mixing sodium lignosulfonate and the carboxymethyl chitosan to obtain a composite emulsifier;

[0008] Step S3: dissolving the compound emulsifier in deionized water, stirring and dissolving, adding polyester block palm oil, stirring at a first stirring speed, and then sequentially adding 2,6-di-tert-butyl-p-cresol, benzotriazole ethanol solution and nonylphenol polyoxyethylene ether, stirring evenly to obtain a biodegradable natural plant extract emulsified oil for hydraulic support.

[0009] Hydrogen peroxide, catalyzed by formic acid, generates highly active formic acid peroxide. As an electrophilic reagent, formic acid peroxide reacts with the double bonds of the fatty acid chains in palm oil to form three-membered cyclic epoxy groups. Unsaturated double bonds are chemically active groups in fatty acid molecules and are susceptible to oxidation, free radical attack, or degradation reactions, generating corrosive substances such as peroxides, aldehydes, and acids. Epoxidation converts the double bonds into chemically inert epoxy groups, reducing the formation of corrosive products. The increased polarity of the molecules after epoxidation makes the oil film formed on the metal surface denser, helping to isolate the metal from corrosion by moisture, oxygen, and corrosive ions. Epoxy groups are highly polar functional groups, and their oxygen atoms have a strong negative charge, which allows them to adsorb to polar sites on the metal surface (the metal oxide layer) through intermolecular forces. This adsorption allows the modified palm oil molecules to adhere more stably to the metal surface, forming a uniform lubricating film. This lubricating film reduces direct contact between the metal surfaces, thereby reducing the coefficient of friction. In addition, epoxidation increases the interaction force between molecules, improves the cohesion between lubricating oil molecules and the stability of the lubricating film, is not easy to break under high pressure or high shear conditions, can continuously provide boundary lubrication, and reduce frictional heat and wear.

[0010] When epoxidized palm oil reacts with boric acid, the epoxy group undergoes a ring-opening reaction to form a boron-oxygen bond or a boron ester structure with the boric acid. The boron atoms in the boron-oxygen bond and the boron ester structure have high electrophilicity, while the oxygen atoms have strong negative charge. This electrical difference significantly enhances the polarity of the molecule. The enhanced polarity enables the boronized palm oil molecules to be adsorbed on the metal surface through intermolecular forces, combining with the metal oxide layer to form a chemical adsorption film, which effectively isolates the direct contact of the metal and reduces friction and adhesion. The boron-oxygen bond has a high bond energy, which makes the adsorption film have excellent stability in high temperature and high pressure environments, providing a continuous lubrication effect. During friction, the boronized product exhibits layered friction interface properties. The boron-oxygen bonds and ester structures within the boronized product are highly directional and symmetrical, tending to form a regular molecular arrangement at the friction interface. The boronized lubricant molecules form a first adsorption film that adheres closely to the metal surface, providing chemical protection. Subsequent layers adhere to the first layer through weak intermolecular interactions, forming a multilayered molecular structure. The weak bonding between these molecular layers allows for relative sliding between them, exhibiting a distinct layered structure. During friction, the molecular layers of the boronized product can achieve interlayer slip under shear stress. Because this slip occurs between the molecular layers rather than through direct contact between the metal surfaces, the interfacial friction coefficient is significantly reduced. When external forces disrupt some of the molecular layers, the molecules of the boronized product can rearrange through weak interactions and fill the lost areas. This dynamic reconfiguration enables the lubricating film to maintain its layered properties, providing stable self-lubrication. The chemical stability of the boron-oxygen bonds and ester structure ensures that the molecular layers are resistant to degradation or chemical decomposition under frictional conditions, enhancing the durability of the lubricating film.

[0011] The adsorption film formed by boron-oxygen bonds and boron ester structures on the metal surface has high chemical stability. This protective film can effectively isolate the metal surface from corrosion by corrosive media. By reducing the contact with corrosive media, the boronized adsorption film reduces the oxidation rate of the metal surface, thereby extending the service life of metal parts. At the same time, boron has natural antioxidant properties, and its compounds can capture free radicals and inhibit oxidation chain reactions, thereby reducing the generation of oxidative degradation products (such as aldehydes, acids and peroxides) in lubricating oils. These oxidative degradation products are the main cause of metal corrosion. Boron modification indirectly reduces the corrosion risk of metals by delaying oxidation reactions. Benzotriazole is an organic compound containing an aromatic ring and a nitrogen heterocycle. The nitrogen atom in benzotriazole carries a lone pair of electrons and can react with uncoordinated metal atoms on the metal surface to form a metal complex. The resulting complex film is highly stable and can effectively prevent the invasion of corrosive ions. When boron modification and benzotriazole are present simultaneously in the lubricating oil system, they exhibit a synergistic effect on the metal surface, thereby significantly enhancing the corrosion protection performance. The boronization product first forms a dense primary protective film on the metal surface through chemical adsorption. This film has strong chemical stability and can prevent most of the penetration of water and oxygen. The benzotriazole molecule is small and can be adsorbed into the microscopic defects and gaps of the boronized film, further filling the integrity of the film layer. The boronized adsorption film serves as a base layer, providing chemical stability and physical barrier. The benzotriazole molecules are adsorbed on its upper layer, further enhancing the thickness and density of the adsorption film, thereby achieving a synergistic corrosion reduction effect.

[0012] Triethyl phosphate undergoes an esterification or ring-opening reaction with the hydroxyl or epoxy groups in the boronated palm oil molecules to form phosphate groups. This chemical modification not only changes the polarity and interfacial properties of the molecule but also enhances the lubrication, corrosion resistance, and wear resistance of the lubricant. The phosphorus atom in triethyl phosphate is positively charged and can undergo nucleophilic substitution with the hydroxyl group to form a phosphate ester bond. The epoxy group also readily undergoes a nucleophilic ring-opening reaction with the phosphorus atom in triethyl phosphate to form a phosphorus-containing esterified product. The ring-opening of the epoxy group forms a stable covalent bond between the phosphate group and the palm oil molecule. The phosphate group has a high polarity, in which the oxygen atoms in the phosphorus-oxygen double bond and the phosphorus-oxygen single bond have significant negative charge. The palm oil molecules with enhanced polarity can be strongly adsorbed to the oxide layer on the metal surface through electrostatic interaction or hydrogen bonding. The phosphate group enhances the interfacial interaction between the lubricant and the metal surface, forming a stable chemical adsorption film. The phosphate adsorption film has a high adsorption energy and can remain stable under high temperature and high pressure conditions and is not easy to fall off. It plays a key protective role under boundary lubrication conditions (i.e., when the metal surfaces are in direct contact), effectively reducing the friction coefficient of the metal surface. The synergistic effect of the phosphate group and the boron-oxygen bond further enhances the lubrication performance. The boron-oxygen bond provides initial adsorption and lubrication, while the phosphate group strengthens the stability of the lubricating film through polar interactions.

[0013] The adsorption film formed by the phosphate group on the metal surface is dense and can effectively prevent direct contact between the corrosive medium and the metal. It not only prevents the diffusion of oxygen, but also reduces the penetration rate of water, thereby significantly slowing down the corrosion reaction of the metal. At the same time, the phosphorus atoms in the phosphate group exhibit strong electrophilicity. Under the action of the metal surface, the phosphate group can hydrolyze to form phosphate ions or metaphosphates. These phosphoric acid derivatives can react with metal oxides to form a phosphate passivation layer. This passivation layer has high chemical stability and can adhere to the metal surface for a long time. It can effectively isolate the corrosive medium from direct contact with the metal surface, and can further enhance the corrosion resistance of the metal surface.

[0014] Caprolactone is a small-molecule monomer with a cyclic ester structure. Its ring structure can undergo ring-opening polymerization to produce polyester segments. The polar groups (phosphate groups or hydroxyl groups) in phosphated palm oil serve as the starting point for the ring-opening polymerization reaction, reacting with the caprolactone monomer, resulting in the caprolactone segments being covalently linked to the phosphated palm oil molecules. The repeated ester bonds and methylene units in the polycaprolactone segments impart flexibility to the polyester segments, allowing them to spread across the friction interface and form a continuous lubricating film. Furthermore, the polar groups in the phosphated palm oil can firmly bind to the metal surface through electrostatic interactions or chemical adsorption, providing the initial adsorption force of the lubricating film. The polyester segments are connected to the phosphated palm oil through a block copolymer structure, ensuring more stable adhesion of the lubricating film to the metal surface. The high molecular weight of the polyester chain segments imparts greater thickness and uniformity to the lubricating film, enhancing its shear resistance and durability. The intermolecular forces of the polymer chains further stabilize the film structure, preventing it from rupturing under high shear forces. The flexibility and fluidity of the polyester chain segments allow the lubricating film to quickly re-spread when locally damaged, ensuring its integrity and lubricating effectiveness during long-term operation. Regarding wear resistance, the flexibility of the polyester chain segments imparts a certain elastic buffering effect to the lubricating film at the friction interface. The flexible molecular chains absorb and disperse mechanical loads, distributing concentrated stress over a larger surface area, thereby reducing localized stress concentration at the friction interface. Furthermore, the polar groups of the phosphated palm oil provide strong adsorption and initial lubrication, while the flexibility and dynamic fluidity of the polyester chain segments enhance the stability and wear resistance of the lubricating film.

[0015] Chitosan is rich in amino and hydroxyl groups. Under alkaline conditions, the amino or hydroxyl groups in the chitosan molecule are first deprotonated to generate amine anions or alcohol anions with stronger nucleophilicity. These active sites undergo nucleophilic substitution reactions with the carbon atoms in the chloroacetic acid molecules, replacing chloride ions and introducing carboxymethyl functional groups, making the chitosan molecule more polar and hydrophilic, significantly improving the solubility and interfacial activity of chitosan. The polar groups (such as hydroxyl, carboxyl and amino) in the carboxymethyl chitosan molecule can be strongly adsorbed to the oxide layer on the metal surface through electrostatic interaction, hydrogen bonding or coordination bonding. This adsorption forms a dense protective film on the metal surface, effectively isolating the external corrosive medium. Since the carboxyl group in carboxymethyl chitosan is a weakly acidic group, it can partially ionize to form carboxylate ions. Carboxylates are anions with strong coordination ability and can form coordination chemical bonds with metal cations. The protons in the carboxyl group exchange with the hydroxyl groups on the surface of the metal oxide to generate water molecules. At the same time, the carboxyl group directly combines with the metal ions on the surface of the metal oxide to form a metal-carboxylate bond. The carboxylate ions act as ligands to attack the metal ions in the metal oxide and coordinate with them to form a stable metal-carboxylate complex. A protective film containing the metal-carboxylate complex is generated on the metal surface. The metal-carboxylate complex has high chemical stability and is difficult to be dissolved or destroyed by water or oxygen, thereby playing a long-term protective role on the metal surface. Sodium lignosulfonate is a low-molecular-weight anionic surfactant containing sulfonic acid groups and aromatic ring structures. The sulfonic acid groups strongly adsorb to the surface of oil droplets, reducing their tendency to coalesce through electrostatic repulsion and significantly reducing the surface tension at the oil-water interface. Metal surface oxides typically appear as positively charged metal cations in aqueous media. Sulfonic acid groups, with their strong negative charge, can bind to the positive charges on the metal surface through electrostatic interactions. The oxygen atoms in the sulfonic acid groups have lone electron pairs that coordinate with cations on the metal surface, forming stable metal-sulfonate bonds. This further enhances the adhesion of sodium lignosulfonate to the metal surface and imparts high chemical stability to the adsorbed layer. Furthermore, in the presence of hydroxyl groups on the metal surface, the oxygen atoms in the sulfonic acid groups can hydrogen bond with these surface hydroxyl groups. This hydrogen bonding further enhances the adsorption stability of sodium lignosulfonate molecules on the metal surface. The multi-point adsorption properties of the sulfonic acid groups enable each sodium lignosulfonate molecule to simultaneously bind to multiple metal cations or surface active sites, forming a uniform, dense adsorption layer on the metal surface, effectively isolating it from corrosive media.

[0016] As a preferred technical solution of the present invention, in step S1, the mass fraction of the hydrogen peroxide is 20-30 wt.%, for example, it can be 20.0 wt.%, 21.0 wt.%, 22.0 wt.%, 23.0 wt.%, 24.0 wt.%, 25.0 wt.%, 26.0 wt.%, 27.0 wt.%, 28.0 wt.%, 29.0 wt.% or 30.0 wt.%, but is not limited to the listed values, and other values ​​not listed within this numerical range are also applicable.

[0017] In some optional examples, the mass of the hydrogen peroxide is 10-15% of the mass of the palm oil, for example, it can be 10.0%, 10.5%, 11.0%, 11.5%, 12.0%, 12.5%, 13.0%, 13.5%, 14.0%, 14.5% or 15.0%, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0018] In some optional examples, the mass of the formic acid is 5-7% of the mass of the palm oil, for example, it can be 5.0%, 5.2%, 5.4%, 5.6%, 5.8%, 6.0%, 6.2%, 6.4%, 6.6%, 6.8% or 7.0%, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0019] In some optional examples, the first temperature is 50-60°C, for example, it can be 50.0°C, 51.0°C, 52.0°C, 53.0°C, 54.0°C, 55.0°C, 56.0°C, 57.0°C, 58.0°C, 59.0°C or 60.0°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0020] In some optional examples, the stirring reaction time at the first temperature is 4-5h, for example, it can be 4.0h, 4.1h, 4.2h, 4.3h, 4.4h, 4.5h, 4.6h, 4.7h, 4.8h, 4.9h or 5.0h, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0021] In some optional examples, the mass of the boric acid is 15-20% of the mass of the epoxidized palm oil, for example, it can be 15.0%, 15.5%, 16.0%, 16.5%, 17.0%, 17.5%, 18.0%, 18.5%, 19.0%, 19.5% or 20.0%, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0022] In some optional examples, the second temperature is 130-140°C, for example, it can be 130.0°C, 131.0°C, 132.0°C, 133.0°C, 134.0°C, 135.0°C, 136.0°C, 137.0°C, 138.0°C, 139.0°C or 140.0°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0023] In some optional examples, the second temperature reaction time is 2-3h, for example, it can be 2.0h, 2.1h, 2.2h, 2.3h, 2.4h, 2.5h, 2.6h, 2.7h, 2.8h, 2.9h or 3.0h, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0024] In some optional examples, the mass of the triethyl phosphate is 10-15% of the mass of the boronated palm oil, for example, it can be 10.0%, 10.5%, 11.0%, 11.5%, 12.0%, 12.5%, 13.0%, 13.5%, 14.0%, 14.5% or 15.0%, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0025] In some optional examples, the mass of the p-toluenesulfonic acid is 0.5-1% of the mass of the boronated palm oil, for example, it can be 0.50%, 0.55%, 0.60%, 0.65%, 0.70%, 0.75%, 0.80%, 0.85%, 0.90%, 0.95% or 1.00%, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0026] In some optional examples, the third temperature is 70-90°C, for example, it can be 70.0°C, 72.0°C, 74.0°C, 76.0°C, 78.0°C, 80.0°C, 82.0°C, 84.0°C, 86.0°C, 88.0°C or 90.0°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0027] In some optional examples, the reaction time at the third temperature is 2-3h, for example, it can be 2.0h, 2.1h, 2.2h, 2.3h, 2.4h, 2.5h, 2.6h, 2.7h, 2.8h, 2.9h or 3.0h, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0028] In some optional examples, the mass of the caprolactone is 20-30% of the mass of the phosphated palm oil, for example, it can be 20.0%, 21.0%, 22.0%, 23.0%, 24.0%, 25.0%, 26.0%, 27.0%, 28.0%, 29.0% or 30.0%, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0029] In some optional examples, the mass of the tetrabutyl titanate is 0.5-1% of the mass of the phosphated palm oil, for example, it can be 0.50%, 0.55%, 0.60%, 0.65%, 0.70%, 0.75%, 0.80%, 0.85%, 0.90%, 0.95% or 1.00%, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0030] In some optional examples, the fourth temperature is 100-120°C, for example, it can be 100.0°C, 102.0°C, 104.0°C, 106.0°C, 108.0°C, 110.0°C, 112.0°C, 114.0°C, 116.0°C, 118.0°C or 120.0°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0031] In some optional examples, the reaction time at the fourth temperature is 3-4h, for example, it can be 3.0h, 3.1h, 3.2h, 3.3h, 3.4h, 3.5h, 3.6h, 3.7h, 3.8h, 3.9h or 4.0h, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0032] As a preferred technical solution of the present invention, in step S2, the mass fraction of the ethanol aqueous solution is 50 wt.%.

[0033] In some optional examples, the swelling stirring time is 30-40 min, for example, it can be 30.0 min, 31.0 min, 32.0 min, 33.0 min, 34.0 min, 35.0 min, 36.0 min, 37.0 min, 38.0 min, 39.0 min or 40.0 min, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0034] In some optional examples, the mass ratio of chitosan to NaOH solution is 1:3.

[0035] In some optional examples, the mass fraction of the NaOH solution is 33 wt.%.

[0036] In some optional examples, the standing time is 30-40 min, for example, it can be 30.0 min, 31.0 min, 32.0 min, 33.0 min, 34.0 min, 35.0 min, 36.0 min, 37.0 min, 38.0 min, 39.0 min or 40.0 min, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0037] In some optional examples, the mass ratio of the chitosan to the chloroacetic acid solution is 1:3.

[0038] In some optional examples, the mass fraction of the chloroacetic acid solution is 60 wt.%.

[0039] In some optional examples, the water bath reaction time is 4-5h, for example, it can be 4.0h, 4.1h, 4.2h, 4.3h, 4.4h, 4.5h, 4.6h, 4.7h, 4.8h, 4.9h or 5.0h, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0040] In some optional examples, the mass ratio of the sodium lignin sulfonate to the carboxymethyl chitosan is 3:1.

[0041] As a preferred technical solution of the present invention, in step S3, the mass ratio of the compound emulsifier to the polyester block palm oil is 1:5.

[0042] In some optional examples, the mass ratio of the deionized water to the polyester block palm oil is 1:3.

[0043] In some optional examples, the first stirring speed is 1500-2000 rpm, for example, it can be 1500 rpm, 1550 rpm, 1600 rpm, 1650 rpm, 1700 rpm, 1750 rpm, 1800 rpm, 1850 rpm, 1900 rpm, 1950 rpm or 2000 rpm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0044] In some optional examples, the stirring time of the first stirring speed is 20-30 min, for example, it can be 20.0 min, 21.0 min, 22.0 min, 23.0 min, 24.0 min, 25.0 min, 26.0 min, 27.0 min, 28.0 min, 29.0 min or 30.0 min, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0045] In some optional examples, the mass of the 2,6-di-tert-butyl-p-cresol is 0.1-0.2% of the mass of the polyester block palm oil, for example, it can be 0.10%, 0.11%, 0.12%, 0.13%, 0.14%, 0.15%, 0.16%, 0.17%, 0.18%, 0.19% or 0.20%, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0046] In some optional examples, the mass fraction of the benzotriazole ethanol solution is 33 wt.%;

[0047] In some optional examples, the mass of the benzotriazole ethanol solution is 0.1-0.2% of the mass of the polyester block palm oil, for example, it can be 0.10%, 0.11%, 0.12%, 0.13%, 0.14%, 0.15%, 0.16%, 0.17%, 0.18%, 0.19% or 0.20%, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0048] In some optional examples, the mass of the nonylphenol polyoxyethylene ether is 0.5-1% of the mass of the polyester block palm oil, for example, it can be 0.50%, 0.55%, 0.60%, 0.65%, 0.70%, 0.75%, 0.80%, 0.85%, 0.90%, 0.95% or 1.00%, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0049] In a second aspect, a degradable natural plant-extracted emulsified oil for a hydraulic support is prepared by the preparation method described in the first aspect.

[0050] Compared with the prior art, the present invention has the following beneficial effects:

[0051] (1) Palm oil is used as the core base oil. Vegetable oil is a renewable resource with good biodegradability and low toxicity. Compared with petroleum-based emulsified oil, it has less long-term impact on the ecological environment and can be naturally degraded by microorganisms without forming persistent pollution. The selection of emulsifiers is also based on natural renewable resources, chitosan and sodium lignosulfonate. These bio-based materials can effectively replace traditional mineral-based emulsifiers, further improving the environmental protection characteristics of the overall product.

[0052] (2) Boronization and phosphating reactions further introduce highly polar boron-oxygen bonds and phosphorus-oxygen bonds. These groups have high metal affinity and can form strong adsorption films on metal surfaces, thereby reducing contact with corrosive media and improving wear resistance and lubrication effects. Block polymerization design enhances the shear resistance and durability of the lubricating film by introducing polyester segments. The intermolecular forces of the polymer chains further stabilize the structure of the lubricating film, preventing it from breaking under high shear forces. At the same time, the flexibility of the polyester segments and the fluidity of the polymer chains enable the lubricating film to quickly re-spread when locally damaged, ensuring the integrity and lubrication effect of the lubricating film during long-term operation.

[0053] (3) The polar groups in the carboxymethyl chitosan molecules can be strongly adsorbed to the oxide layer on the metal surface through electrostatic interaction, hydrogen bonding or coordination bonding. This adsorption forms a dense protective film on the metal surface, effectively isolating the external corrosive medium. At the same time, the carboxyl groups directly combine with the metal ions on the surface of the metal oxide to form a stable metal-carboxylate complex. A protective film containing the metal-carboxylate complex is formed on the metal surface. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1 TEM image of the carboxymethylated chitosan prepared in Example 1 of the present invention (scale: 50 nm);

[0055] Figure 2 TEM image of the carboxymethylated chitosan prepared in Example 1 of the present invention (scale: 30 nm);

[0056] Figure 3 This is a SEM image of the degradable natural plant extract emulsified oil for hydraulic support prepared in Example 1 of the present invention (scale: 100 μm);

[0057] Figure 4 This is a SEM image of the degradable natural plant extract emulsified oil for hydraulic support prepared in Example 1 of the present invention (scale: 25 μm);

[0058] Figure 5 This is a SEM image of the degradable natural plant extract emulsified oil for hydraulic support prepared in Example 1 of the present invention (scale: 5 μm). DETAILED DESCRIPTION

[0059] The technical solutions of the present invention are described in detail below in conjunction with specific embodiments and their accompanying drawings. The embodiments described herein are specific embodiments of the present invention and are used to illustrate the concept of the present invention; these descriptions are explanatory and exemplary and should not be understood as limiting the embodiments of the present invention and the scope of protection of the present invention. In addition to the embodiments described herein, those skilled in the art can also adopt other obvious technical solutions based on the contents disclosed in the claims of this application and its specification, including technical solutions that adopt any obvious replacements and modifications to the embodiments described herein.

[0060] The chemical reagents used in the examples and comparative examples of the present invention are all commercially available products and have not been subjected to any further purification treatment.

[0061] Example 1

[0062] This embodiment provides a method for preparing a degradable natural plant-extracted emulsified oil for a hydraulic support, the preparation method specifically comprising the following steps:

[0063] Step S1, mixing 100g of palm oil, 12g of 22wt.% hydrogen peroxide and 5g of formic acid, heating to 54°C and stirring for reaction for 4.2h, washing the product after the reaction to obtain epoxidized palm oil, mixing 100g of epoxidized palm oil with 17g of boric acid, heating to 133°C, stirring and reacting for 2.8h, cooling to room temperature after the reaction to obtain boronized palm oil, then mixing 100g of boronized palm oil, 12g of triethyl phosphate and 0.6g of p-toluenesulfonic acid, heating to 76°C and reacting for 2.6h to obtain phosphated palm oil, then mixing 100g of phosphated palm oil, 22g of caprolactone and 0.65g of tetrabutyl titanate, heating to 115°C under a nitrogen atmosphere and reacting for 3.2h, and rotary evaporating after the reaction to obtain polyester block palm oil;

[0064] Step S2: dispersing 5 g of chitosan in 30 g of ethanol aqueous solution, stirring for 33 min to swell the chitosan, adding 15 g of 33 wt.% NaOH solution to the swollen chitosan solution and letting it stand for 33 min to obtain an alkalized chitosan solution, adding 15 g of chloroacetic acid solution to the alkalized chitosan solution, heating to 53° C. in a water bath, stirring and reacting for 4.6 h, filtering, washing, and vacuum drying to obtain carboxymethyl chitosan after completion of the reaction, and then uniformly mixing 15 g of sodium lignosulfonate with 5 g of carboxymethyl chitosan to obtain a composite emulsifier;

[0065] Step S3: dissolve 30 g of the compound emulsifier in 50 g of deionized water, stir and dissolve, then add 150 g of polyester block palm oil, stir at 1700 rpm, then add 0.15 g of 2,6-di-tert-butyl-p-cresol, 0.21 g of benzotriazole ethanol solution and 0.75 g of nonylphenol polyoxyethylene ether in sequence, and stir evenly to obtain a biodegradable natural plant extract emulsified oil for hydraulic support.

[0066] Figure 1 TEM image of the carboxymethylated chitosan prepared in this example (scale 50 nm); Figure 2 TEM image of the carboxymethylated chitosan prepared in this example (scale 30 nm); Figure 3 、 Figure 4 and Figure 5 This is the SEM image of the emulsified oil droplet. It can be clearly seen that the droplet surface is smooth and has no obvious defects. No holes or cracks are observed. There are no cracks or particles attached, and the boundaries are clear, indicating that the emulsion system has strong interfacial stability.

[0067] Example 2

[0068] This embodiment provides a method for preparing a degradable natural plant-extracted emulsified oil for a hydraulic support, the preparation method specifically comprising the following steps:

[0069] Step S1, mixing 100g of palm oil, 10g of 26wt.% hydrogen peroxide and 6g of formic acid, heating to 50°C and stirring for reaction for 4.7h, washing the product after the reaction to obtain epoxidized palm oil, mixing 100g of epoxidized palm oil with 15g of boric acid, heating to 130°C, stirring and reacting for 3.0h, cooling to room temperature after the reaction to obtain boronized palm oil, then mixing 100g of boronized palm oil, 10g of triethyl phosphate and 0.9g of p-toluenesulfonic acid, heating to 71°C and reacting for 2.1h to obtain phosphated palm oil, then mixing 100g of phosphated palm oil, 28g of caprolactone and 0.50g of tetrabutyl titanate, heating to 108°C under a nitrogen atmosphere and reacting for 3.7h, and rotary evaporating after the reaction to obtain polyester block palm oil;

[0070] Step S2: 6 g of chitosan was dispersed in 36 g of ethanol aqueous solution, stirred for 30 min to swell the chitosan, and then 18 g of 33 wt.% NaOH solution was added to the swollen chitosan solution and allowed to stand for 30 min to obtain an alkalized chitosan solution. 18 g of chloroacetic acid solution was added to the alkalized chitosan solution, and the temperature was raised to 50 ° C. under water bath conditions, and stirred for reaction for 5.0 h. After the reaction was completed, the solution was filtered, washed, and vacuum dried to obtain carboxymethyl chitosan. 15 g of wood was added. Sodium sulfonate and 5g of carboxymethyl chitosan are mixed evenly to obtain a compound emulsifier; step S3, dissolving 30g of the compound emulsifier in 50g of deionized water, stirring to dissolve, and then adding 150g of polyester block palm oil, stirring at 1500rpm, and then adding 0.24g of 2,6-di-tert-butyl-p-cresol, 0.27g of benzotriazole ethanol solution and 1.29g of nonylphenol polyoxyethylene ether in sequence, and stirring evenly to obtain a biodegradable natural plant extract emulsified oil for hydraulic support.

[0071] Example 3

[0072] This embodiment provides a method for preparing a degradable natural plant-extracted emulsified oil for a hydraulic support, the preparation method specifically comprising the following steps:

[0073] Step S1, 100g of palm oil, 15g of 20wt.% hydrogen peroxide and 7g of formic acid are mixed, heated to 60°C and stirred for reaction for 4.0h, and after the reaction, the product is washed to obtain epoxidized palm oil, 100g of epoxidized palm oil is mixed with 18g of boric acid, heated to 137°C, and stirred for reaction for 2.4h, and after the reaction is completed, it is cooled to room temperature to obtain boronized palm oil, and then 100g of boronized palm oil, 13g of triethyl phosphate and 1.0g of p-toluenesulfonic acid are mixed, heated to 84°C and fully reacted for 3.0h to obtain phosphated palm oil, and then 100g of phosphated palm oil, 30g of caprolactone and 1.0g of tetrabutyl titanate are mixed, heated to 116°C under a nitrogen atmosphere and fully reacted for 3.4h, and after the reaction is completed, rotary evaporation is performed to obtain polyester block palm oil;

[0074] Step S2: 7 g of chitosan was dispersed in 42 g of ethanol aqueous solution, stirred for 39 min to swell the chitosan, and then 21 g of 33 wt.% NaOH solution was added to the swollen chitosan solution and allowed to stand for 39 min to obtain an alkalized chitosan solution. 21 g of chloroacetic acid solution was added to the alkalized chitosan solution, and the temperature was raised to 57 ° C under water bath conditions, and stirred for reaction for 4.3 h. After the reaction, the solution was filtered, washed, and vacuum dried to obtain carboxymethyl chitosan. 15 g of wood was added to the solution. The invention discloses a method for preparing a biodegradable natural plant-derived emulsified oil for hydraulic support, comprising: dissolving 30 g of the composite emulsifier in 50 g of deionized water, stirring to dissolve the mixture, adding 150 g of polyester block palm oil, stirring at 2000 rpm, and then sequentially adding 0.3 g of 2,6-di-tert-butyl-p-cresol, 0.15 g of benzotriazole ethanol solution, and 1.5 g of nonylphenol polyoxyethylene ether, stirring evenly, and obtaining a biodegradable natural plant-derived emulsified oil for hydraulic support.

[0075] Example 4

[0076] This embodiment provides a method for preparing a degradable natural plant-extracted emulsified oil for a hydraulic support, the preparation method specifically comprising the following steps:

[0077] Step S1, mixing 100g of palm oil, 14g of 30wt.% hydrogen peroxide and 5.5g of formic acid, heating to 57°C and stirring for reaction for 5.0h, washing the product after the reaction to obtain epoxidized palm oil, mixing 100g of epoxidized palm oil with 20g of boric acid, heating to 140°C, stirring and reacting for 2.0h, cooling to room temperature after the reaction to obtain boronized palm oil, then mixing 100g of boronized palm oil, 15g of triethyl phosphate and 0.5g of p-toluenesulfonic acid, heating to 90°C and reacting for 2.4h to obtain phosphated palm oil, then mixing 100g of phosphated palm oil, 20g of caprolactone and 0.84g of tetrabutyl titanate, heating to 120°C under a nitrogen atmosphere and reacting for 4.0h, and rotary evaporation after the reaction to obtain polyester block palm oil;

[0078] Step S2: dispersing 5 g of chitosan in 30 g of ethanol aqueous solution, stirring for 36 min to swell the chitosan, adding 15 g of 33 wt.% NaOH solution to the swollen chitosan solution and letting it stand for 31 min to obtain an alkalized chitosan solution, adding 15 g of chloroacetic acid solution to the alkalized chitosan solution, heating to 60° C. in a water bath, stirring and reacting for 4.0 h, filtering, washing, and vacuum drying to obtain carboxymethyl chitosan after completion of the reaction, and then uniformly mixing 15 g of sodium lignosulfonate with 5 g of carboxymethyl chitosan to obtain a composite emulsifier;

[0079] Step S3: dissolve 30 g of the compound emulsifier in 50 g of deionized water, stir and dissolve, then add 150 g of polyester block palm oil, stir at 1900 rpm, then add 0.25 g of 2,6-di-tert-butyl-p-cresol, 0.25 g of benzotriazole ethanol solution and 1.1 g of nonylphenol polyoxyethylene ether in sequence, and stir evenly to obtain a biodegradable natural plant extract emulsified oil for hydraulic support.

[0080] Comparative Example 1

[0081] This comparative example provides a method for preparing a biodegradable natural plant-extracted emulsified oil for a hydraulic support. The difference from Example 1 is that the mass of boric acid in step S1 is adjusted to 30 g, which is 13 g more than that in Example 1. The other process parameters and operating conditions are exactly the same as those in Example 1.

[0082] Comparative Example 2

[0083] This comparative example provides a method for preparing a biodegradable natural plant-extracted emulsified oil for a hydraulic support. The difference from Example 1 is that the mass of boric acid in step S1 is adjusted to 4 g, which is 13 g less than that in Example 1. The other process parameters and operating conditions are exactly the same as those in Example 1.

[0084] Comparative Example 3

[0085] This comparative example provides a method for preparing a biodegradable natural plant-extracted emulsified oil for a hydraulic support. The difference from Example 1 is that the mass of caprolactone in step S1 is adjusted to 42 g, which is 20 g more than that in Example 1. The other process parameters and operating conditions are exactly the same as those in Example 1.

[0086] Comparative Example 4

[0087] This comparative example provides a method for preparing a biodegradable natural plant-extracted emulsified oil for a hydraulic support. The difference from Example 1 is that the mass of caprolactone in step S1 is adjusted to 2 g, which is 20 g less than that in Example 1. The other process parameters and operating conditions are exactly the same as those in Example 1.

[0088] The degradable emulsified oils for hydraulic supports prepared in Examples 1-4 and Comparative Examples 1-4 were tested according to the standard MT 76-2011 “Emulsified oils, concentrated solutions and high-water content hydraulic fluids for hydraulic supports”. The test results are shown in Table 1.

[0089] Table 1 Test results of degradable natural plant extract emulsified oil for hydraulic supports prepared in Examples 1-4 and Comparative Examples 1-4

[0090]

[0091] As shown in Table 1, compared to Example 1, all samples in the anti-corrosion test of Comparative Example 1 showed rust, and their lubricity, freeze-thaw resistance, and stability were all reduced. In the anti-corrosion test of Comparative Example 2, all samples showed rust, and their lubricity, freeze-thaw resistance, and stability were all reduced. This is because the excessive amount of boric acid in Comparative Example 1 means that the boric acid that did not react with the epoxy groups may precipitate in the emulsified oil or react with water to form soluble borates, which destroys the stability of the emulsified oil and the lubricating film formed, reducing the anti-corrosion effect. At the same time, the excessive amount of boric acid leads to excessive crosslinking between the emulsified oil molecules, reducing the flexibility of the molecular chain and its freeze-thaw resistance. In Comparative Example 2, the boric acid quality is too low, the boronization reaction is insufficient, the density and stability of the metal surface protective film decreases, and the proportion of borate esters also decreases, making it difficult to form a stable lubricating film. At the same time, the reduced amount of boric acid reduces the intermolecular forces, and the freeze-thaw resistance and stability decrease.

[0092] As shown in Table 1, compared with Example 1, corrosion occurred in all the corrosion resistance tests of Comparative Example 3, and lubricity, freeze-thaw resistance, and stability were all reduced. Rust also occurred in all the corrosion resistance tests of Comparative Example 4, and lubricity, freeze-thaw resistance, and stability were all reduced. Caprolactone combines with the hydroxyl groups in phosphated palm oil through a ring-opening polymerization reaction to form a polyester block structure. The polyester block introduces polar ester groups and flexible chain segments. These groups can form a dense protective film on the metal surface through physical adsorption and chemical bonding. In Comparative Example 1, the amount of caprolactone is insufficient, the polyester block chain is short, and the number of polar ester groups is reduced, resulting in a less dense protective film formed by the emulsified oil on the metal surface, reduced corrosion resistance, insufficient number of polar groups, reduced adsorption capacity of the lubricating film under high load, reduced lubricity, and the formed polyester block chain is short, which weakens the intermolecular force of the emulsified oil, and reduced freeze-thaw resistance and stability. In Comparative Example 2, the amount of caprolactone used is too much, the polyester chain is too long, and the molecular flexibility of the emulsified oil may be too high, resulting in a decrease in the mechanical strength of the protective film. Excessive caprolactone may also reduce the hydrophobicity of the emulsified oil, causing water to more easily contact the metal surface, thereby weakening the anti-corrosion and lubrication effects. The polyester chain is too long, and although the flexibility of the emulsified oil is improved, the intermolecular force may be too strong, affecting the dispersibility and compatibility of the emulsified oil, and reducing the freeze-thaw resistance and stability.

[0093] The above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing a degradable natural plant-extracted emulsified oil for hydraulic supports, characterized in that: The preparation method is: Step S1, mixing palm oil, hydrogen peroxide and formic acid, heating and reacting to obtain epoxidized palm oil, mixing the epoxidized palm oil with boric acid, heating and reacting to obtain boronated palm oil, then mixing the boronated palm oil, triethyl phosphate and p-toluenesulfonic acid, heating and reacting to obtain phosphated palm oil, then mixing the phosphated palm oil, caprolactone and tetrabutyl titanate, heating and reacting under a nitrogen atmosphere to obtain polyester block palm oil; Step S2, dispersing chitosan in an ethanol aqueous solution, stirring to swell the chitosan, adding a NaOH solution to the swollen chitosan solution and allowing the solution to stand to obtain an alkalized chitosan solution, adding a chloroacetic acid solution to the alkalized chitosan solution, heating the solution in a water bath to react, obtaining carboxymethyl chitosan, and then uniformly mixing sodium lignosulfonate and the carboxymethyl chitosan to obtain a composite emulsifier; Step S3, dissolving the compound emulsifier in deionized water, adding polyester block palm oil, stirring at a first stirring speed, and then adding 2,6-di-tert-butyl-p-cresol, benzotriazole ethanol solution and nonylphenol polyoxyethylene ether in sequence to obtain a biodegradable natural plant extract emulsified oil for hydraulic support; The mass of the boric acid is 15-20% of the mass of the epoxidized palm oil; The mass of the caprolactone is 20-30% of the mass of the phosphated palm oil; The mass ratio of the compound emulsifier to the polyester block palm oil is 1:5; The mass ratio of the deionized water to the polyester block palm oil is 1:

3.

2. The method for preparing a degradable natural plant-extracted emulsified oil for hydraulic supports according to claim 1, characterized in that: In step S1, The mass of the hydrogen peroxide is 10-15% of the mass of the palm oil; The mass of the formic acid is 5-7% of the mass of the palm oil.

3. The method for preparing a degradable natural plant-extracted emulsified oil for hydraulic supports according to claim 1, characterized in that: In step S1, The mass of the triethyl phosphate is 10-15% of the mass of the boronated palm oil; The mass of the p-toluenesulfonic acid is 0.5-1% of the mass of the boronated palm oil.

4. The method for preparing a degradable natural plant-extracted emulsified oil for hydraulic supports according to claim 1, characterized in that: In step S1, The mass of the tetrabutyl titanate is 0.5-1% of the mass of the phosphated palm oil.

5. The method for preparing a degradable natural plant-extracted emulsified oil for hydraulic supports according to claim 1, characterized in that: In step S2, The mass ratio of chitosan to ethanol aqueous solution is 1:6; The mass fraction of the ethanol aqueous solution is 50 wt.%.

6. The method for preparing a degradable natural plant-extracted emulsified oil for hydraulic supports according to claim 1, characterized in that: In step S2, The mass ratio of chitosan to NaOH solution is 1:3; The mass fraction of the NaOH solution is 33 wt.%; The standing time is 30-40 minutes.

7. The method for preparing a degradable natural plant-extracted emulsified oil for hydraulic supports according to claim 1, characterized in that: In step S2, The mass ratio of the chitosan to the chloroacetic acid solution is 1:3; The mass ratio of the sodium lignin sulfonate to the carboxymethyl chitosan is 3:

1.

8. The method for preparing a biodegradable natural plant-extracted emulsified oil for hydraulic supports according to claim 1, characterized in that: In step S3, The first stirring speed is 1500-2000 rpm; The stirring time at the first stirring speed is 20-30 min.

9. The method for preparing a degradable natural plant-extracted emulsified oil for hydraulic supports according to claim 1, characterized in that: In step S3, The mass of the 2,6-di-tert-butyl-p-cresol is 0.1-0.2% of the mass of the polyester block palm oil; The mass of the benzotriazole ethanol solution is 0.1-0.2% of the mass of the polyester block palm oil; The mass of the nonylphenol polyoxyethylene ether is 0.5-1% of the mass of the polyester block palm oil.

10. The degradable natural plant-extracted emulsified oil for hydraulic supports obtained according to the preparation method according to any one of claims 1 to 9.

Images