Degradable emulsified oil extracted from natural plants and used for hydraulic support and preparation method of degradable emulsified oil

Abstract

The invention belongs to the technical field of hydraulic support oil, and provides degradable emulsified oil extracted from natural plants and used for a hydraulic support and a preparation method of the degradable emulsified oil. The preparation method comprises the following steps: firstly, performing multi-step chemical modification on palm oil, including epoxidation, boronation, phosphorization and block polymerization reaction, and introducing an epoxy group into the epoxidation reaction, so that the reaction activity of grease is improved; the polarity of the grease and the forming ability of a lubricating film are further enhanced through boronizing and phosphating reactions; through a block polymerization reaction with caprolactone, the stability and wear resistance of the lubricating film are enhanced; secondly, chitosan is subjected to carboxymethylation modification, carboxyl in carboxymethyl chitosan can react with oxide on the metal surface, and a chemical passivation protective film is formed; sulfonic acid groups in the sodium lignin sulfonate are combined with the metal surface through electrostatic adsorption, a protective layer is further constructed, and a multi-layer compact protective film is formed on the metal surface through the synergistic effect of the two, so that the corrosion resistance of the emulsified oil is remarkably improved.

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] As the main working medium of the hydraulic support system of coal mines, hydraulic support emulsified oil is one of the important factors affecting the performance of the support. Traditional emulsified oil is mainly based on mineral oil and is composed of additives such as emulsifiers, rust inhibitors, and anti-wear agents. However, traditional emulsified oil will produce a large amount of waste liquid during use, which causes serious pollution to the environment. In addition, the mineral oil and certain chemical additives contained in traditional emulsified oil have certain toxicity and non-degradability, which not only harm the ecological environment, but also may have adverse effects on human health. Compared with traditional mineral oil-based emulsified oil, vegetable oil has the advantages of wide sources, renewable and strong biodegradability. In addition, vegetable oil contains more polar groups, which can provide good lubricity and anti-wear properties, but bio-based emulsified oil is easily contaminated by microorganisms, and the by-products generated by microbial decomposition may further aggravate metal corrosion. Therefore, the development of a degradable natural plant extract emulsified oil for hydraulic supports with good lubricity and corrosion resistance has a good application prospect. Summary of the invention

[0003] In view of the shortcomings of the prior art, the present invention aims to provide a degradable natural plant-extracted emulsified oil for hydraulic support and a preparation method thereof. Palm oil is subjected to epoxidation, boronization, phosphating and block copolymerization to prepare polyester block castor oil with excellent lubrication performance 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. Carboxymethyl chitosan is compounded with sodium lignosulfonate, and the synergistic effect of the two is utilized to enhance the emulsification 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 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 for reaction, cooling to room temperature after the reaction to obtain boronized palm oil, then mixing the boronized palm oil, triethyl phosphate and p-toluenesulfonic acid, heating to a third temperature for reaction to obtain phosphated palm oil, then mixing phosphated castor oil, caprolactone and tetrabutyl titanate, heating to a fourth temperature under a nitrogen atmosphere for reaction to obtain, and rotary evaporating to obtain polyester block castor oil after the reaction;

[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 under a water bath condition and stirring to react, filtering, washing, and vacuum drying after the reaction to obtain carboxymethyl chitosan, and then uniformly mixing sodium lignosulfonate and carboxymethyl chitosan to obtain a composite emulsifier;

[0008] Step S3, dissolving the compound emulsifier in deionized water, adding polyester block castor oil after stirring and dissolving, 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, stirring evenly to obtain a biodegradable natural plant extract emulsified oil for hydraulic support.

[0009] Hydrogen peroxide generates highly active formic acid peroxide under the catalytic action of formic acid. Formic acid peroxide, as an electrophilic reagent, can react with the double bonds of the fatty acid chain in palm oil to generate three-membered cyclic epoxy groups. Unsaturated double bonds are chemically more active groups in fatty acid molecules, which are easily attacked by oxidation, free radicals or degradation reactions, generating corrosive substances such as peroxides, aldehydes and acids. Epoxidation converts double bonds into chemically inert epoxy groups to reduce the generation of corrosive products. The increase in molecular polarity after epoxidation makes the oil film formed on the metal surface more compact, which helps to isolate the corrosion of water, oxygen and corrosive ions on the metal. At the same time, the epoxy group is a highly polar functional group, and its oxygen atom has a strong negative charge, which can be adsorbed to the polar sites (metal oxide layer) on the metal surface through intermolecular forces. This adsorption enables the modified palm oil molecules to be more stably attached to the metal surface, forming a uniform lubricating film, which can reduce direct contact between the metal surface and thus reduce the friction coefficient. In addition, epoxidation increases the interaction between molecules, improves the cohesion between lubricant molecules and the stability of the lubricating film, makes it less likely to break under high pressure or high shear conditions, and can continuously provide boundary lubrication, reducing frictional heat and wear.

[0010] When epoxidized palm oil reacts with boric acid, the epoxy group will undergo a ring-opening reaction to form a boron-oxygen bond or a boron ester structure with 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 increases 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 under high temperature and high pressure environments, providing a continuous lubrication effect. During friction, the boronized product exhibits certain lamellar friction interface characteristics. The boron-oxygen bonds and boron ester structures in the boronized product have high directionality and symmetry, and tend to form regular molecular arrangements on the friction interface. The boronized lubricant molecules form the first layer of adsorption film, which is close to the metal surface and provides chemical protection. The subsequent layers are attached to the first layer through weak intermolecular interactions, forming a multi-layer molecular structure. The binding force between these molecular layers is weak, so that the molecular layers can slide relative to each other, showing obvious lamellar characteristics. During friction, the molecular layers of the boronized product can achieve interlayer slip under the action of shear stress. Since this slip occurs between molecular layers rather than direct contact between metal surfaces, the interfacial friction coefficient is significantly reduced. When external forces destroy part of the molecular layers, the molecules of the boronized product can rearrange and fill the lost area through weak interactions. This dynamic reconstruction enables the lubricating film to continue to maintain its lamellar characteristics and provide a stable self-lubricating effect. The chemical stability of the boron-oxygen bonds and boron ester structures ensures that the molecular layers are not easily degraded or chemically decomposed under friction 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 borated adsorption film reduces the oxidation rate of the metal surface, thereby extending the service life of metal parts. At the same time, the boron element 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. Boration modification indirectly reduces the risk of metal corrosion 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 has high stability and can effectively prevent the invasion of corrosive ions. When boron modification and benzotriazole exist in the lubricating oil system at the same time, they show a synergistic effect on the metal surface, thereby significantly enhancing the anti-corrosion performance. The boronized 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 the bottom layer, providing chemical stability and physical barriers. 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 esterification or ring-opening reaction with hydroxyl or epoxy groups in boronated palm oil molecules to generate phosphate groups. This chemical modification not only changes the polarity and interfacial properties of the molecule, but also improves the lubrication, corrosion resistance and wear resistance of the lubricant. The phosphorus atom in triethyl phosphate is positively charged and can undergo nucleophilic substitution reaction with hydroxyl groups to generate phosphate bonds. The epoxy group easily undergoes nucleophilic ring-opening reaction with the phosphorus atom in triethyl phosphate to generate phosphorus-containing esterification products. The ring-opening of the epoxy group allows the phosphate group to form a stable covalent connection with 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 action or hydrogen bonding. The phosphate group enhances the interfacial interaction between the lubricating oil and the metal surface to form 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 the 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 show strong electrophilicity. Under the action of the metal surface, the phosphate group can be hydrolyzed to form phosphate ions or metaphosphates. These phosphoric acid derivatives can react with metal oxides to form a phosphate passivation layer. The passivation layer has high chemical stability and can adhere to the metal surface for a long time. It can effectively isolate the direct contact between the corrosive medium and 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 cyclic structure can undergo ring-opening polymerization to generate polyester segments. The polar groups (phosphate groups or hydroxyl groups) in phosphated palm oil can serve as the starting point of the ring-opening polymerization reaction and react with the caprolactone monomer to connect the caprolactone segments to the phosphated palm oil molecules through covalent bonds. The repeated ester bonds and methylene units in the polycaprolactone segments give the polyester segments flexibility, allowing the polyester segments to spread on the friction interface to form a continuous lubricating film. The polar groups in the phosphated palm oil can be firmly bonded to the metal surface through electrostatic action 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 to ensure that the lubricating film is more stably attached to the metal surface. The high molecular weight of the polyester chain segment makes the lubricating film thicker and more uniform, and enhances the shear resistance and durability of the lubricating film. The intermolecular force of the polymer chain further stabilizes the structure of the lubricating film and prevents it from breaking under high shear force. The flexibility of the polyester chain segment and the fluidity of the polymer chain enable the lubricating film to quickly re-spread when it is locally damaged, ensuring the integrity and lubrication effect of the lubricating film during long-term operation. In terms of wear resistance, the flexibility of the polyester chain segment enables the lubricating film to exhibit a certain elastic buffering effect on the friction interface. The flexible molecular chain can absorb and disperse the mechanical load, dispersing the concentrated stress to a larger surface area, thereby reducing the local stress concentration on the friction interface. The polar groups of the phosphated palm oil provide strong adsorption and initial lubrication guarantee, while the flexibility and dynamic fluidity of the polyester chain segment 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 molecules more polar and hydrophilic, and significantly improving the solubility and interfacial activity of chitosan. Polar groups (such as hydroxyl, carboxyl and amino) in carboxymethyl chitosan molecules can strongly adsorb to the oxide layer on the metal surface through electrostatic action, hydrogen bond or coordination bond. 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 be partially ionized to form carboxylate ions. Carboxyl is an anion with strong coordination ability and can form a coordination chemical bond 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 attack the metal ions in the metal oxide as ligands 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 in the molecule. The sulfonic acid groups can be strongly adsorbed on the surface of oil droplets, reducing the tendency of oil droplets to coalesce through electrostatic repulsion, and significantly reducing the surface tension of the oil-water interface. Metal surface oxides usually appear as positively charged metal cation points in aqueous media. Sulfonic acid groups have strong negative charges and can combine with the positive charges on the metal surface through electrostatic interactions; the oxygen atoms in the sulfonic acid groups have lone pairs of electrons, which can coordinate with the cations on the metal surface to form a stable metal-sulfonate bond, further enhancing the adhesion of sodium lignosulfonate on the metal surface and giving the adsorption layer a higher chemical stability; at the same time, in the presence of hydroxyl groups on the metal surface, the oxygen atoms in the sulfonic acid groups can also combine with the surface hydroxyl groups through hydrogen bonds. The formation of hydrogen bonds further enhances the adsorption stability of sodium lignosulfonate molecules on the metal surface. The multi-point adsorption characteristics of the sulfonic acid groups enable each sodium lignosulfonate molecule to combine with multiple metal cations or surface active points at the same time, thereby forming a uniform and dense adsorption layer on the metal surface, achieving the effect of isolating the corrosive medium.

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

[0018] In some optional examples, the mass of formic acid is 5-7% of the mass of 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 the numerical range are also applicable.

[0019] In some optional instances, 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 instances, 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 the numerical range are also applicable.

[0022] In some optional instances, 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 the 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 the numerical range are also applicable.

[0026] In some optional instances, 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 the 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 the numerical range are also applicable.

[0030] In some optional instances, 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, 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 50wt.%.

[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 chitosan to 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 castor oil is 1:5.

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

[0043] In some optional examples, the first stirring speed is 1500-2000rpm, for example, it can be 1500rpm, 1550rpm, 1600rpm, 1650rpm, 1700rpm, 1750rpm, 1800rpm, 1850rpm, 1900rpm, 1950rpm or 2000rpm, 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 the 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 castor 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 33wt.%;

[0047] In some optional examples, the mass of the benzotriazole ethanol solution is 0.1-0.2% of the mass of the polyester block castor 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.

[0048] In some optional examples, the mass of the nonylphenol polyoxyethylene ether is 0.5-1% of the mass of the polyester block castor 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 the numerical range are also applicable.

[0049] In a second aspect, a degradable natural plant-extracted emulsified oil for 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 causing persistent pollution. The selection of emulsifiers is also based on natural renewable resources, such as 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, which reduce the contact with corrosive media and improve the wear resistance and lubrication effect. 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 and prevent 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 it is 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 effects, hydrogen bonds or coordination bonds. 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, and 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 carboxymethylated chitosan prepared in Example 1 of the present invention (scale: 50 nm);

[0055] Figure 2 TEM image of 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 solution of the present invention is described in detail below in conjunction with specific embodiments and their accompanying drawings. The embodiments recorded herein are specific embodiments of the present invention, which are used to illustrate the concept of the present invention; these descriptions are explanatory and exemplary and should not be construed as limitations on the embodiments of the present invention and the scope of protection of the present invention. In addition to the embodiments recorded 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 recorded herein.

[0060] The chemical reagents used in the examples and comparative examples of the present invention are all commercially available products without any further purification treatment.

[0061] Example 1

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

[0063] Step S1, 100g palm oil, 12g hydrogen peroxide with a mass fraction of 22wt.% and 5g formic acid are mixed, heated to 54°C and stirred for reaction for 4.2h, after the reaction is completed, the product is washed to obtain epoxidized palm oil, 100g epoxidized palm oil is mixed with 17g boric acid, the temperature is raised to 133°C, and the reaction is fully stirred for 2.8h, after the reaction is completed, it is cooled to room temperature to obtain boronized palm oil, and then 100g boronized palm oil, 12g triethyl phosphate and 0.6g p-toluenesulfonic acid are mixed, the temperature is raised to 76°C and the reaction is fully reacted for 2.6h to obtain phosphated palm oil, and then 100g phosphated castor oil, 22g caprolactone and 0.65g tetrabutyl titanate are mixed, the temperature is raised to 115°C under a nitrogen atmosphere and the reaction is fully reacted for 3.2h, and after the reaction is completed, the polyester block castor oil is obtained by rotary evaporation;

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

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

[0066] Figure 1 TEM image of carboxymethylated chitosan prepared in this example (scale 50 nm); Figure 2 TEM image of 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 surface of the droplet is smooth and has no obvious defects. No holes or cracks are observed. There is no crack or particle attachment, and the boundary is 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 hydraulic support, and the preparation method specifically comprises the following steps:

[0069] Step S1, 100g of palm oil, 10g of hydrogen peroxide with a mass fraction of 26wt.% and 6g of formic acid are mixed, heated to 50°C and stirred for reaction for 4.7h, after the reaction is completed, the product is washed to obtain epoxidized palm oil, 100g of epoxidized palm oil is mixed with 15g of boric acid, the temperature is raised to 130°C, and the reaction is fully stirred for 3.0h, after the reaction is completed, it is cooled to room temperature to obtain boronized palm oil, and then 100g of boronized palm oil, 10g of triethyl phosphate and 0.9g of p-toluenesulfonic acid are mixed, the temperature is raised to 71°C and the reaction is fully reacted for 2.1h to obtain phosphated palm oil, and then 100g of phosphated castor oil, 28g of caprolactone and 0.50g of tetrabutyl titanate are mixed, the temperature is raised to 108°C under a nitrogen atmosphere and the reaction is fully reacted for 3.7h, and after the reaction is completed, the polyester block castor oil is obtained by rotary evaporation;

[0070] Step S2, dispersing 6g of chitosan in 36g of ethanol aqueous solution, stirring for 30min to swell the chitosan, then adding 18g of NaOH solution with a mass fraction of 33wt.% to the swollen chitosan solution and standing for 30min to obtain an alkalized chitosan solution, adding 18g of chloroacetic acid solution to the alkalized chitosan solution, heating to 50°C under water bath conditions and stirring for reaction for 5.0h, filtering, washing, and vacuum drying after the reaction to obtain carboxymethyl chitosan, and then mixing 15g of sodium lignosulfonate with 5g of carboxymethyl chitosan to obtain a composite emulsifier;

[0071] Step S3, dissolving 30g of the composite emulsifier in 50g of deionized water, stirring and dissolving, adding 150g of polyester block castor 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, stirring evenly to obtain a biodegradable natural plant extract emulsified oil for hydraulic support.

[0072] Example 3

[0073] This embodiment provides a method for preparing a degradable natural plant-extracted emulsified oil for hydraulic support, and the preparation method specifically comprises the following steps:

[0074] Step S1, 100g of palm oil, 15g of hydrogen peroxide with a mass fraction of 20wt.% and 7g of formic acid are mixed, heated to 60°C and stirred for reaction for 4.0h, after the reaction is completed, the product is washed to obtain epoxidized palm oil, 100g of epoxidized palm oil is mixed with 18g of boric acid, the temperature is raised to 137°C, and the reaction is fully stirred for 2.4h, 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, the temperature is raised to 84°C and the reaction is fully reacted for 3.0h to obtain phosphated palm oil, and then 100g of phosphated castor oil, 30g of caprolactone and 1.0g of tetrabutyl titanate are mixed, the temperature is raised to 116°C under a nitrogen atmosphere and the reaction is fully reacted for 3.4h, and after the reaction is completed, the polyester block castor oil is obtained by rotary evaporation;

[0075] Step S2, dispersing 7g of chitosan in 42g of ethanol aqueous solution, stirring for 39min to swell the chitosan, then adding 21g of a 33wt.% NaOH solution to the swollen chitosan solution and standing for 39min to obtain an alkalized chitosan solution, adding 21g of a chloroacetic acid solution to the alkalized chitosan solution, heating to 57°C under a water bath condition and stirring for reaction for 4.3h, filtering, washing, and vacuum drying after the reaction to obtain carboxymethyl chitosan, then mixing 15g of sodium lignosulfonate with 5g of carboxymethyl chitosan to obtain a composite emulsifier;

[0076] Step S3, dissolving 30g of the composite emulsifier in 50g of deionized water, stirring and dissolving, adding 150g of polyester block castor oil, stirring at 2000rpm, and then adding 0.3g of 2,6-di-tert-butyl-p-cresol, 0.15g of benzotriazole ethanol solution and 1.5g of nonylphenol polyoxyethylene ether in sequence, stirring evenly to obtain a biodegradable natural plant extract emulsified oil for hydraulic support.

[0077] Example 4

[0078] This embodiment provides a method for preparing a degradable natural plant-extracted emulsified oil for hydraulic support, and the preparation method specifically comprises the following steps:

[0079] Step S1, 100g of palm oil, 14g of 30wt.% hydrogen peroxide and 5.5g of formic acid are mixed, heated to 57°C and stirred for reaction for 5.0h, after the reaction is completed, the product is washed to obtain epoxidized palm oil, 100g of epoxidized palm oil is mixed with 20g of boric acid, the temperature is raised to 140°C, and the reaction is fully stirred for 2.0h, after the reaction is completed, it is cooled to room temperature to obtain boronized palm oil, and then 100g of boronized palm oil, 15g of triethyl phosphate and 0.5g of p-toluenesulfonic acid are mixed, the temperature is raised to 90°C and the reaction is fully reacted for 2.4h to obtain phosphated palm oil, and then 100g of phosphated castor oil, 20g of caprolactone and 0.84g of tetrabutyl titanate are mixed, the temperature is raised to 120°C under a nitrogen atmosphere and the reaction is fully reacted for 4.0h, and after the reaction is completed, the polyester block castor oil is obtained by rotary evaporation;

[0080] Step S2, dispersing 5g of chitosan in 30g of ethanol aqueous solution, stirring for 36min to swell the chitosan, then adding 15g of NaOH solution with a mass fraction of 33wt.% to the swollen chitosan solution and letting it stand for 31min to obtain an alkalized chitosan solution, adding 15g of chloroacetic acid solution to the alkalized chitosan solution, heating to 60°C under water bath conditions and stirring for reaction for 4.0h, filtering, washing, and vacuum drying after the reaction to obtain carboxymethyl chitosan, and then mixing 15g of sodium lignosulfonate with 5g of carboxymethyl chitosan to obtain a composite emulsifier;

[0081] Step S3, dissolving 30g of the composite emulsifier in 50g of deionized water, stirring and dissolving, adding 150g of polyester block castor oil, stirring at 1900rpm, and then adding 0.25g of 2,6-di-tert-butyl-p-cresol, 0.25g of benzotriazole ethanol solution and 1.1g of nonylphenol polyoxyethylene ether in sequence, stirring evenly to obtain a biodegradable natural plant extract emulsified oil for hydraulic support.

[0082] Comparative Example 1

[0083] This comparative example provides a method for preparing a biodegradable natural plant-extracted emulsified oil for hydraulic supports. 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.

[0084] Comparative Example 2

[0085] This comparative example provides a method for preparing a biodegradable natural plant-extracted emulsified oil for hydraulic supports. 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.

[0086] Comparative Example 3

[0087] This comparative example provides a method for preparing a biodegradable natural plant-extracted emulsified oil for hydraulic supports. 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.

[0088] Comparative Example 4

[0089] This comparative example provides a method for preparing a biodegradable natural plant-extracted emulsified oil for hydraulic supports. 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.

[0090] 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.

[0091] Table 1 Test results of degradable natural plant extract emulsified oil for hydraulic support prepared in Examples 1-4 and Comparative Examples 1-4

[0092]

[0093] As shown in Table 1, compared with Example 1, the anti-corrosion experiments of Comparative Example 1 all showed rust, and the lubricity, freeze-thaw resistance and stability were all reduced; the anti-corrosion experiments of Comparative Example 2 all showed rust, and the lubricity, freeze-thaw resistance and stability were all reduced. This is because there is too much boric acid in Comparative Example 1, and the boric acid that has not reacted with the epoxy group may precipitate in the emulsified oil or react with water to form a soluble borate, which destroys the stability of the emulsified oil and the lubricating film formed, and the anti-corrosion effect is reduced. At the same time, too much boric acid causes the degree of cross-linking between the emulsified oil molecules to be too high, reducing the flexibility of the molecular chain and its freeze-thaw resistance. In Comparative Example 2, the quality of boric acid is too low, the boration reaction is insufficient, the density and stability of the metal surface protective film are reduced, and the proportion of boric acid esters also decreases, making it difficult to form a stable lubricating film. At the same time, the amount of boric acid is reduced, the intermolecular force is reduced, and the freeze-thaw resistance and stability are reduced.

[0094] As shown in Table 1, compared with Example 1, the anti-corrosion experiments of Comparative Example 3 all showed rust, and the lubricity, freeze-thaw resistance and stability were all reduced; the anti-corrosion experiments of Comparative Example 4 all showed rust, and the lubricity, freeze-thaw resistance and stability were all reduced. Caprolactone combines with the hydroxyl group in the phosphated palm oil through a ring-opening polymerization reaction to form a polyester block structure, and the polyester block introduces polar ester groups and flexible chain links. 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 the protective film formed by the emulsified oil on the metal surface being not dense enough, the anti-corrosion property is reduced, the number of polar groups is insufficient, the adsorption capacity of the lubricating film under high load is reduced, the lubricity is reduced, and the polyester block chain formed is short, the intermolecular force of the emulsified oil is weakened, and the freeze-thaw resistance and stability are reduced. 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.

[0095] The above description is only a specific implementation mode 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 are 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 support, characterized in that: The preparation method is: Step S1, mixing palm oil, hydrogen peroxide and formic acid, heating reaction to obtain epoxidized palm oil, mixing epoxidized palm oil with boric acid, heating reaction to obtain boronized palm oil, then mixing boronized palm oil, triethyl phosphate and p-toluenesulfonic acid, heating reaction to obtain phosphated palm oil, then mixing phosphated castor oil, caprolactone and tetrabutyl titanate, heating reaction under nitrogen atmosphere to obtain polyester block castor 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 letting it 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 carboxymethyl chitosan to obtain a composite emulsifier; Step S3, dissolving the compound emulsifier in deionized water, adding polyester block castor 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 degradable natural plant extraction emulsified oil for hydraulic support.

2. The method for preparing a degradable natural plant-extracted emulsified oil for hydraulic support 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 support according to claim 1, characterized in that: In step S1, The mass of the boric acid is 15-20% of the mass of the epoxidized palm oil; 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 support according to claim 1, characterized in that: In step S1, The mass of the caprolactone is 20-30% of the mass of the phosphated palm oil; 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 support 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 support 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 33wt.%; The standing time is 30-40 minutes.

7. The method for preparing a degradable natural plant-extracted emulsified oil for hydraulic support according to claim 1, characterized in that: In step S2, The mass ratio of chitosan to 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 degradable natural plant-extracted emulsified oil for hydraulic support according to claim 1, characterized in that: In step S3, The mass ratio of the composite emulsifier to the polyester block castor oil is 1:5; The mass ratio of the deionized water to the polyester block castor oil is 1:3; The first stirring speed is 1500-2000rpm; 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 support 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 castor oil; The mass of the benzotriazole ethanol solution is 0.1-0.2% of the mass of the polyester block castor oil; The mass of the nonylphenol polyoxyethylene ether is 0.5-1% of the mass of the polyester block castor oil.

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

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