Zero-discharge concentrated solution for hydraulic support

Abstract

The invention belongs to the technical field of transmission medium hydraulic fluid, and particularly relates to a zero-discharge concentrated solution for a hydraulic support. The bio-based lubricating oil comprises the following raw materials in parts by weight: 65-80 parts of base oil, 2-5 parts of an emulsifier, 1-2 parts of a bio-based antioxidant, 5-12 parts of a bio-based thickener, 0.01-0.02 part of a foam inhibitor and 4-6 parts of a nano lubricant. The multi-level synergistic effect of the plant-based oil, the bio-based thickener and the nano lubricant enables the concentrate to maintain stable rheological properties and provide lasting lubrication in high temperature, high pressure and even harsh environments. A network and a film layer with multiple protection functions are formed on the lubricating surface and in an oil product, so that abrasion is greatly reduced, the oxidation resistance is improved, and the service life of equipment is prolonged. Meanwhile, the bio-based materials and the environment-friendly additives also ensure that negative effects of oil products on the environment are minimized in the using and discharging process, and efficient operation and environment friendliness of a hydraulic system are achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of transmission medium hydraulic fluid, and in particular relates to a concentrated fluid for a zero-emission hydraulic support. Background Art

[0002] Concentrated oil for hydraulic supports is a component of a high-water hydraulic fluid designed specifically for underground hydraulic support systems in coal mines. Unlike emulsified oil, concentrated oil is usually not used directly, but is diluted in a certain proportion to become hydraulic fluid, which is widely used in equipment such as hydraulic supports and external injection single hydraulic props. This hydraulic fluid plays a vital role in the application of fully-mechanized coal mine working faces. It is not only the "blood" of the hydraulic system, but also crucial to the support, lifting, movement, push and slide, and overload protection of hydraulic supports. Concentrated liquid for zero-emission hydraulic supports is an environmentally friendly working medium designed specifically for the electro-hydraulic control system of coal mine hydraulic supports. After preparation, this concentrated liquid can be used as a transmission medium in the hydraulic system to support the support, lifting and movement of hydraulic supports. Compared with traditional emulsions, concentrated liquid for zero-emission hydraulic supports has higher stability, cleanliness and excellent biodegradability, which can effectively reduce the impact on the environment and help achieve the "zero emission" goal in the coal mine production process. Due to the characteristics of the composition, traditional emulsions are prone to oil and soap separation during use, which will not only block the system, but also cause leakage, thereby causing groundwater pollution. The new environmentally friendly concentrated fluid has made effective improvements to these problems, which can not only ensure the normal operation of the hydraulic system, but also significantly reduce or even avoid the negative impact on the environment. In order to meet the increasingly stringent environmental protection requirements, especially in areas facing serious environmental pollution challenges, it is particularly important to develop and apply this environmentally friendly zero-emission hydraulic support concentrated fluid. By using this environmentally friendly hydraulic fluid, it can not only ensure the efficient operation of the hydraulic support system, but also significantly reduce the negative impact on the environment during the coal mine production process, and promote the sustainable development of the coal mining industry. Therefore, it is extremely necessary to develop and apply an environmentally friendly zero-emission hydraulic support concentrated fluid. Summary of the invention

[0003] In view of the defects of the prior art, the object of the present invention is to provide a concentrated liquid for a zero-emission hydraulic support.

[0004] The technical effect described in the present invention is achieved through the following technical scheme: a concentrated liquid for a zero-emission hydraulic support, which comprises the following raw materials in parts by weight: 65 to 80 parts of base oil, 2 to 5 parts of emulsifier, 1 to 2 parts of bio-based antioxidant, 5 to 12 parts of bio-based thickener, 0.01 to 0.02 parts of antifoaming agent and 4 to 6 parts of nano-lubricant.

[0005] Preferably, the base oil comprises the following components in parts by weight: 30 to 35 parts of linseed oil, 30 to 35 parts of rapeseed oil and 5 to 10 parts of polycaprolactone.

[0006] Preferably, the emulsifier is any one of monolaurin, triglyceride, monolaurin and glyceryl palmitate.

[0007] Preferably, the foam suppressor is polydimethylsiloxane.

[0008] Preferably, the bio-based antioxidant is composed of the following raw materials in parts by weight: 0.3-0.5 parts of rosemary extract, 0.4-0.8 parts of tea polyphenols, 0.2-0.4 parts of alginic acid and 0.1-0.3 parts of citric acid.

[0009] Preferably, the composition of the bio-based thickener includes hydroxypropyl guar gum, hydroxypropyl methylcellulose, chitosan and sodium alginate, and the specific preparation steps are as follows: A1: Add hydroxypropyl guar gum, hydroxypropyl methylcellulose and sodium alginate into deionized water respectively, heat to 50-60°C, stir and dissolve evenly to obtain 0.5-1.5wt% hydroxypropyl guar gum solution, 0.5-1wt% hydroxypropyl methylcellulose solution and 0.2-0.5wt% sodium alginate solution; add chitosan into deionized water, stir and mix evenly, adjust pH to 3.5-4, and obtain 0.5-1wt% chitosan solution; A2: The hydroxypropyl guar gum solution, hydroxypropyl methylcellulose solution, chitosan solution and sodium alginate solution prepared in step A1 are added in sequence and stirred and mixed evenly, and after ultrasonic treatment at 60W for 20-30min, 1M CaCl2 solution is slowly added dropwise, the pH is adjusted to 4-5, stirred, and allowed to react for 6-12h, and vacuum dried at 50-60°C for 12-24h to obtain a bio-based thickener; Preferably, in step A2, the volume ratio of the hydroxypropyl guar gum solution, the hydroxypropyl methylcellulose solution, the chitosan solution and the sodium alginate solution is 1:1:1:1; and the amount of the CaCl2 solution is 1 to 1.5% of the volume of the substrate mixed solution.

[0010] Preferably, the nano-lubricant is graphene@SiO2-Al2O3 nanoparticles, and the specific preparation steps are as follows: B1: Add graphene to deionized water, perform ultrasonic treatment at 60-80W for 30-60min, disperse evenly, and obtain a 0.05-0.1wt% graphene dispersion; add ethyl silicate to anhydrous ethanol, stir and mix evenly, and obtain a silicon solution; B2: Slowly add the silicon solution prepared in step B1 into deionized water, then add hydrochloric acid to adjust the pH to 3.5-4, stir and react for 1-2 hours to obtain silica sol; add aluminum isopropanol into anhydrous ethanol, adjust the pH to 4-6, stir and mix evenly to obtain aluminum sol; mix the silica sol and aluminum sol evenly to obtain a mixed sol; B3: Mix the graphene dispersion prepared in step B1 with the mixed sol prepared in step B2, perform ultrasonic treatment at 60-80W for 20-30min, disperse evenly, control the temperature at 40-60°C, stir and react for 2-4h, cool to room temperature, centrifuge, filter, and heat treat at 150-200°C for 2-4h to obtain graphene@SiO2-Al2O3 nanoparticles; Preferably, in step B1, the volume ratio of ethyl silicate to anhydrous ethanol is 1:4-6; Preferably, in step B2, the volume ratio of the silicon solution to deionized water is 1 to 1.5:1; the volume ratio of aluminum isopropanol to anhydrous ethanol is 1 g:10 to 12 mL; the volume ratio of the silica sol to the aluminum sol is 2 to 3:1; Preferably, in step B3, the volume ratio of the graphene dispersion and the mixed sol is 1:5.

[0011] Furthermore, the preparation method of the concentrated liquid for zero-emission hydraulic support described in the present invention comprises the following steps: S1: Mix linseed oil and rapeseed oil in the base oil evenly, then add polycaprolactone, increase the temperature to 60-70° C., stir and mix thoroughly, then add bio-based antioxidant and emulsifier, stir at 300-500 rpm for 5-10 minutes, and obtain an oil phase; S2: adding the bio-based thickener to deionized water, raising the temperature to 40-60° C., stirring and dispersing uniformly, and obtaining a 5-10 wt% bio-based thickening solution; slowly adding the bio-based thickener to the oil phase prepared in step S1, raising the temperature to 50-60° C., stirring at 300-500 rpm for 15-30 min, and then raising the speed to 2000-3000 rpm, stirring for 5-10 min, and obtaining an emulsified system; S3: Disperse the graphene@SiO2-Al2O3 nanoparticles in deionized water, disperse them evenly by ultrasonic treatment, and obtain a 0.1-0.5wt% dispersion; add the dispersion and the antifoaming agent to the emulsified system prepared in step S2, heat to 40-60°C, stir and mix evenly, then cool to room temperature, let stand for 30-60min, vacuum dry at 50-60°C for 8-12h, adjust the pH to 8-9, and obtain a concentrated solution.

[0012] The beneficial effects of the present invention are as follows: The present invention uses linseed oil and rapeseed oil as plant-based base oils. These two oils have excellent natural lubricity, can effectively reduce the friction and wear of metal surfaces, and extend the service life of hydraulic supports; at the same time, the addition of polycaprolactone (PCL) further improves the viscosity index and thermal stability of the oil, especially under high temperature conditions, and significantly improves the performance of the hydraulic fluid. The present invention introduces a variety of bio-based thickeners into the base oil system to optimize the rheological properties and stability of the hydraulic fluid, including hydroxypropyl guar gum (HPG), hydroxypropyl methylcellulose (HPMC), chitosan, and sodium alginate. Among them, hydroxypropyl guar gum has good swelling and thickening properties, can be quickly dispersed in the liquid phase and form a stable three-dimensional network structure with other polymers; when used together with chitosan and sodium alginate and other polymers with positive and negative charges, a more dense thickening network can be constructed by means of charge interaction or hydrogen bonding, which significantly improves the viscosity and rheological stability of the hydraulic fluid. Hydroxypropyl methylcellulose, with its surface active characteristics, can play a stabilizing role at the oil / adjuvant interface, forming a complementary thickening effect with hydroxypropyl guar gum and chitosan, and maintaining excellent thickening performance in a wide pH range and temperature range, thereby significantly improving the rheological properties of hydraulic fluid under high temperature conditions. Chitosan can not only synergize with hydroxypropyl guar gum and hydroxypropyl methylcellulose polymers through ionic bonds, hydrogen bonds, etc. to enhance the firmness of the gel network, improve the shear stability and wear resistance of the hydraulic fluid, but also form a dense protective film on the metal surface, reduce direct contact between friction pairs, and significantly reduce the wear rate. Sodium alginate prevents stratification or precipitation of the liquid during storage and use by forming a stable gel network structure, ensuring long-term consistency of oil performance; the "chitosan-sodium alginate" gel system formed between it and chitosan can also significantly improve the viscoelasticity and adhesion of the solution, further enhancing rheological stability.

[0013] The present invention uses graphene, SiO2 and Al2O3 nanoparticles as nano-lubricants. Graphene, with its two-dimensional layered structure and high thermal conductivity, can form an ultra-thin lubricating film on the friction surface, significantly reduce the friction coefficient, reduce energy loss and improve the overall efficiency of the equipment; while SiO2 and Al2O3 nanoparticles fill the tiny defects on the metal surface to form a solid protective layer to prevent direct contact, greatly reduce wear and extend the service life of the equipment. The synergistic effect of graphene and SiO2-Al2O3 nanoparticles further enhances the stability of oil products in high temperature environments, avoiding oil product decomposition or failure; nanoparticles can also work with antioxidants such as tea polyphenols to effectively delay the oxidation process of oil products, reduce the deterioration rate, extend the service life, and thus reduce the replacement frequency and reduce resource consumption and environmental burden. In addition, under the stable support of the thickener network, the nanoparticles are not easy to aggregate or settle due to high temperature or shear force, and effectively play the role of friction reduction, anti-wear and anti-oxidation throughout the service life cycle.

[0014] In summary, the multi-level synergistic effect of plant-based oils, bio-based thickeners and nano-lubricants enables the concentrate of the present invention to maintain stable rheological properties and provide long-lasting lubrication in high temperature, high pressure and even harsh environments. By forming a network and film layer with multiple protective functions on the lubricating surface and inside the oil, wear is greatly reduced, antioxidant performance is improved and the service life of the equipment is extended. At the same time, these bio-based materials and environmentally friendly additives also ensure that the negative impact of the oil on the environment during use and discharge is minimized, achieving efficient operation and environmental friendliness of the hydraulic system. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings in the following description are only for the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0016] Figure 1 1 is a graph showing the friction performance test results of the concentrated liquids prepared in Example 2 of the present invention and Comparative Examples 1 to 3; Figure 2 It is a graph showing the accelerated aging performance test results of the concentrated solutions prepared in Example 2 of the present invention and Comparative Examples 1 to 3. DETAILED DESCRIPTION

[0017] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them; based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. It should be noted that, unless otherwise specified, the raw materials involved in the present invention are purchased through conventional commercial channels.

[0018] Example 1: A concentrate for a zero-emission hydraulic support, comprising the following raw materials in parts by weight: 65 parts of base oil, 2 parts of emulsifier, 1 part of bio-based antioxidant, 5 parts of bio-based thickener, 0.01 parts of antifoaming agent and 4 parts of nano-lubricant.

[0019] The composition of the base oil includes the following components in parts by weight: 30 parts of linseed oil, 30 parts of rapeseed oil and 5 parts of polycaprolactone.

[0020] The bio-based antioxidant is composed of the following raw materials in parts by weight: 0.3 parts of rosemary extract, 0.4 parts of tea polyphenols, 0.2 parts of alginic acid and 0.1 parts of citric acid.

[0021] The composition of the bio-based thickener includes hydroxypropyl guar gum, hydroxypropyl methylcellulose, chitosan and sodium alginate. The specific preparation steps are as follows: A1: Add hydroxypropyl guar gum, hydroxypropyl methylcellulose and sodium alginate into deionized water respectively, heat to 50°C, stir and dissolve evenly to obtain 0.5wt% hydroxypropyl guar gum solution, 0.5wt% hydroxypropyl methylcellulose solution and 0.2wt% sodium alginate solution; add chitosan into deionized water, stir and mix evenly, adjust the pH to 3.5, and obtain 0.5wt% chitosan solution; A2: 200 mL of hydroxypropyl guar gum solution, 200 mL of hydroxypropyl methylcellulose solution, 200 mL of chitosan solution and 200 mL of sodium alginate solution prepared in step A1 were added in sequence and stirred and mixed evenly. After ultrasonic treatment at 60 W for 20 min, 8 mL of 1 M CaCl2 solution was slowly added dropwise, the pH was adjusted to 4, stirred, allowed to react for 6 h, and vacuum dried at 50 ° C for 24 h to obtain a bio-based thickener; The nanolubricant is graphene@SiO2-Al2O3 nanoparticles, and the specific preparation steps are as follows: B1: 0.05 g of graphene was added to 100 mL of deionized water, and ultrasonic treatment was performed at 60 W for 60 min to disperse the graphene uniformly to obtain a 0.05 wt% graphene dispersion; 20 mL of ethyl silicate was added to 80 mL of anhydrous ethanol, and the mixture was stirred to obtain a silicon solution; B2: Slowly add 100 mL of the silicon solution prepared in step B1 into 100 mL of deionized water, then add hydrochloric acid to adjust the pH to 3.5, stir and react for 1 hour to obtain silica sol; add 10 g of aluminum isopropanol to 100 mL of anhydrous ethanol, adjust the pH to 4, stir and mix evenly to obtain aluminum sol; mix 200 mL of silica sol and 100 mL of aluminum sol evenly to obtain a mixed sol; B3: 60 mL of the graphene dispersion prepared in step B1 was mixed with 300 mL of the mixed sol prepared in step B2, and the mixture was subjected to 60 W ultrasonic treatment for 30 min to disperse the mixture evenly. The mixture was stirred at 40 ° C for 4 h, cooled to room temperature, centrifuged, filtered, and heat treated at 150 ° C for 4 h to obtain graphene@SiO2-Al2O3 nanoparticles. The preparation steps of concentrated liquid for zero-emission hydraulic support are as follows: S1: Mix linseed oil and rapeseed oil in the base oil evenly, then add polycaprolactone, raise the temperature to 60°C, stir and mix thoroughly, then add bio-based antioxidant and monolaurin, stir at 300 rpm for 10 minutes, and obtain an oil phase; S2: adding the bio-based thickener to deionized water, raising the temperature to 40°C, stirring and dispersing uniformly, and obtaining a 5wt% bio-based thickening solution; slowly adding the bio-based thickener to the oil phase prepared in step S1, raising the temperature to 50°C, stirring at 300 rpm for 30 minutes, and then raising the speed to 2000 rpm, stirring for 10 minutes, and obtaining an emulsified system; S3: Disperse the graphene@SiO2-Al2O3 nanoparticles in deionized water, disperse them evenly by ultrasonic treatment, and obtain a 0.1wt% dispersion; add the dispersion and polydimethylsiloxane to the emulsified system prepared in step S2, heat to 40°C, stir and mix evenly, then cool to room temperature, let stand for 30 minutes, vacuum dry at 50°C for 12 hours, adjust the pH to 8, and obtain a concentrated solution.

[0022] Example 2: A concentrate for a zero-emission hydraulic support, comprising the following raw materials in parts by weight: 75 parts of base oil, 4 parts of emulsifier, 1.5 parts of bio-based antioxidant, 10 parts of bio-based thickener, 0.015 parts of antifoaming agent and 5 parts of nano-lubricant.

[0023] The composition of the base oil includes the following components in parts by weight: 34 parts of linseed oil, 33 parts of rapeseed oil and 8 parts of polycaprolactone.

[0024] The bio-based antioxidant is composed of the following raw materials in parts by weight: 0.4 parts of rosemary extract, 0.6 parts of tea polyphenols, 0.3 parts of alginic acid and 0.2 parts of citric acid.

[0025] The composition of the bio-based thickener includes hydroxypropyl guar gum, hydroxypropyl methylcellulose, chitosan and sodium alginate. The specific preparation steps are as follows: A1: Add hydroxypropyl guar gum, hydroxypropyl methylcellulose and sodium alginate into deionized water respectively, heat to 55°C, stir and dissolve evenly to obtain 1wt% hydroxypropyl guar gum solution, 0.8wt% hydroxypropyl methylcellulose solution and 0.3wt% sodium alginate solution; add chitosan into deionized water, stir and mix evenly, adjust the pH to 3.8, and obtain 0.8wt% chitosan solution; A2: 200 mL of hydroxypropyl guar gum solution, 200 mL of hydroxypropyl methylcellulose solution, 200 mL of chitosan solution and 200 mL of sodium alginate solution prepared in step A1 were added in sequence and stirred and mixed evenly. After ultrasonic treatment at 60 W for 25 min, 10 mL of 1 M CaCl2 solution was slowly added dropwise, the pH was adjusted to 4.5, stirred, allowed to react for 10 h, and vacuum dried at 55 ° C for 18 h to obtain a bio-based thickener; The nanolubricant is graphene@SiO2-Al2O3 nanoparticles, and the specific preparation steps are as follows: B1: 0.08 g of graphene was added to 100 mL of deionized water, and ultrasonic treatment was performed at 70 W for 45 min to disperse the graphene uniformly to obtain a 0.08 wt% graphene dispersion; 30 mL of ethyl silicate was added to 150 mL of anhydrous ethanol, and the mixture was stirred to obtain a silicon solution; B2: Slowly add 150 mL of the silicon solution prepared in step B1 to 100 mL of deionized water, then add hydrochloric acid to adjust the pH to 3.8, and stir the reaction for 1.5 hours to obtain silica sol; add 10 g of aluminum isopropanol to 110 mL of anhydrous ethanol, adjust the pH to 5, and stir to mix evenly to obtain aluminum sol; mix 250 mL of silica sol and 100 mL of aluminum sol evenly to obtain a mixed sol; B3: 60 mL of the graphene dispersion prepared in step B1 was mixed with 300 mL of the mixed sol prepared in step B2, and the mixture was subjected to ultrasonic treatment at 70 W for 25 min to achieve uniform dispersion. The mixture was stirred at 50 ° C for 3 h, cooled to room temperature, centrifuged, filtered, and heat treated at 180 ° C for 3 h to obtain graphene@SiO2-Al2O3 nanoparticles. The preparation steps of concentrated liquid for zero-emission hydraulic support are as follows: S1: Mix linseed oil and rapeseed oil in the base oil evenly, then add polycaprolactone, raise the temperature to 65°C, stir and mix thoroughly, then add bio-based antioxidant and triglyceride, stir at 400 rpm for 8 minutes to obtain an oil phase; S2: adding the bio-based thickener to deionized water, raising the temperature to 50°C, stirring and dispersing uniformly, and obtaining an 8wt% bio-based thickening solution; slowly adding the bio-based thickener to the oil phase prepared in step S1, raising the temperature to 55°C, stirring at 400 rpm for 25 min, and then raising the speed to 2500 rpm, stirring for 8 min, and obtaining an emulsified system; S3: Disperse the graphene@SiO2-Al2O3 nanoparticles in deionized water, disperse them evenly by ultrasonic treatment, and obtain a 0.3wt% dispersion; add the dispersion and polydimethylsiloxane to the emulsified system prepared in step S2, heat to 50°C, stir and mix evenly, then cool to room temperature, let stand for 50 minutes, vacuum dry at 55°C for 10 hours, adjust the pH to 8.5, and obtain a concentrate.

[0026] Example 3: A concentrate for a zero-emission hydraulic support, comprising the following raw materials in parts by weight: 80 parts of base oil, 5 parts of emulsifier, 2 parts of bio-based antioxidant, 12 parts of bio-based thickener, 0.02 parts of antifoaming agent and 6 parts of nano-lubricant.

[0027] The composition of the base oil includes the following components by weight: 35 parts of linseed oil, 35 parts of rapeseed oil and 10 parts of polycaprolactone.

[0028] The bio-based antioxidant is composed of the following raw materials in parts by weight: 0.5 parts of rosemary extract, 0.8 parts of tea polyphenols, 0.4 parts of alginic acid and 0.3 parts of citric acid.

[0029] The composition of the bio-based thickener includes hydroxypropyl guar gum, hydroxypropyl methylcellulose, chitosan and sodium alginate. The specific preparation steps are as follows: A1: Add hydroxypropyl guar gum, hydroxypropyl methylcellulose and sodium alginate into deionized water respectively, heat to 60°C, stir and dissolve evenly to obtain 1.5wt% hydroxypropyl guar gum solution, 1wt% hydroxypropyl methylcellulose solution and 0.5wt% sodium alginate solution; add chitosan into deionized water, stir and mix evenly, adjust the pH to 4, and obtain 1wt% chitosan solution; A2: 200 mL of hydroxypropyl guar gum solution, 200 mL of hydroxypropyl methylcellulose solution, 200 mL of chitosan solution and 200 mL of sodium alginate solution prepared in step A1 were added in sequence and stirred and mixed evenly. After 60 W ultrasonic treatment for 30 min, 12 mL of 1 M CaCl2 solution was slowly added dropwise, the pH was adjusted to 5, stirred, allowed to react for 12 h, and vacuum dried at 60 ° C for 12 h to obtain a bio-based thickener; The nanolubricant is graphene@SiO2-Al2O3 nanoparticles, and the specific preparation steps are as follows: B1: 0.1 g of graphene was added to 100 mL of deionized water, and ultrasonic treatment was performed at 80 W for 30 min to disperse the graphene uniformly to obtain a 0.1 wt% graphene dispersion; 30 mL of ethyl silicate was added to 180 mL of anhydrous ethanol, and the mixture was stirred to obtain a silicon solution; B2: Slowly add 200 mL of the silicon solution prepared in step B1 to 150 mL of deionized water, then add hydrochloric acid to adjust the pH to 4, and stir the reaction for 2 hours to obtain silica sol; add 10 g of aluminum isopropanol to 120 mL of anhydrous ethanol, adjust the pH to 6, and stir to mix uniformly to obtain aluminum sol; mix 300 mL of silica sol and 100 mL of aluminum sol uniformly to obtain a mixed sol; B3: 60 mL of the graphene dispersion prepared in step B1 was mixed with 300 mL of the mixed sol prepared in step B2, and the mixture was subjected to 80 W ultrasonic treatment for 20 min to disperse the mixture evenly. The mixture was stirred at 60 ° C for 2 h, cooled to room temperature, centrifuged, filtered, and heat treated at 200 ° C for 2 h to obtain graphene@SiO2-Al2O3 nanoparticles. The preparation steps of concentrated liquid for zero-emission hydraulic support are as follows: S1: Mix linseed oil and rapeseed oil in the base oil evenly, then add polycaprolactone, raise the temperature to 70°C, stir and mix thoroughly, then add bio-based antioxidant and monolaurin, stir at 500 rpm for 5 minutes, and obtain an oil phase; S2: adding the bio-based thickener to deionized water, raising the temperature to 60°C, stirring and dispersing uniformly, and obtaining a 10wt% bio-based thickening solution; slowly adding the bio-based thickener to the oil phase prepared in step S1, raising the temperature to 60°C, stirring at 500 rpm for 15 minutes, and then raising the speed to 3000 rpm, stirring for 5 minutes, and obtaining an emulsified system; S3: Disperse the graphene@SiO2-Al2O3 nanoparticles in deionized water, disperse them evenly by ultrasonic treatment, and obtain a 0.5wt% dispersion; add the dispersion and polydimethylsiloxane to the emulsified system prepared in step S2, heat to 60°C, stir and mix evenly, then cool to room temperature, let stand for 60 minutes, vacuum dry at 60°C for 8 hours, adjust the pH to 9, and obtain a concentrated solution.

[0030] Comparative Example 1: The operation of Comparative Example 1 is substantially the same as that of Example 2, except that no bio-based antioxidant is added in Comparative Example 1.

[0031] Comparative Example 2: The operation of Comparative Example 2 is basically the same as that of Example 2, except that no nano-lubricant is added in Comparative Example 2.

[0032] Comparative Example 3: The operation of Comparative Example 3 is substantially the same as that of Example 2, except that in Comparative Example 3, hydroxypropyl methylcellulose in the biological thickener is removed.

[0033] Performance Testing: Ecotoxicity test: The test was carried out using earthworms, and the earthworm culture medium was used as a benchmark to prepare a control group (blank control) and a treatment group (50 mL / L of the concentrated solution prepared in Examples 1 to 3); the blank control was an earthworm culture medium without any treatment, and 120 earthworms were randomly assigned to the above four test groups, with 120 earthworms in each group. After culturing for 7 days at 20°C and pH 6.5, the earthworm mortality rate was calculated (mortality rate (%) = (initial number - number after the test) × 100%), and the weight changes of earthworms were measured on the 2nd, 4th and 7th days (20 earthworms were randomly selected from each group for weighing, and the average weight change of the whole group was estimated and recorded, and the weight change percentage was calculated = (average weight after the test - average weight before the test) / average weight before the test × 100%). The results are shown in Table 1 below.

[0034] Table 1. Ecotoxicity test results of concentrate

[0035] It can be seen from the results in Table 1 that the concentrated solution prepared by the present invention does not show obvious toxicity to earthworms, and Example 3 prepared with the maximum proportion of dosage also does not cause obvious harm to earthworms. The concentrated solution prepared by the present invention will not cause obvious impact on the ecological environment and can be effectively used for a long time.

[0036] Friction performance test: The friction performance of the concentrates prepared in Example 2 and Comparative Examples 1 to 3 was tested according to MT / T 76-2011 standard. The maximum no-seizure load test results are as follows: Figure 1 shown.

[0037] Depend on Figure 1 It can be seen from the results that the concentrate prepared by the present invention has an extremely high maximum no-seizure load value and exhibits excellent friction performance; from the results of Comparative Example 1 and Example 2, it can be seen that the lack of antioxidants makes the concentrate susceptible to oxidation, and the lubrication performance is affected to a certain extent during long-term use; from the results of Comparative Example 2 and Example 2, it can be seen that the lack of graphene @SiO2-Al2O3 nanoparticles significantly reduces the lubrication performance, resulting in a higher friction coefficient and wear rate; from the results of Comparative Example 3 and Example 2, it can be seen that hydroxypropyl methylcellulose, as a surfactant, stabilizes the oil / auxiliary agent interface and enhances the thickener network. After its absence, the viscosity and rheological properties of the hydraulic fluid decrease, resulting in an insufficiently dense thickening network, reduced protection of the metal surface, and further reduced wear resistance.

[0038] Thermal stability test: The thermal stability of the concentrates prepared in Example 2 and Comparative Examples 1 to 3 was tested according to MT / T 76-2011 standard. The results are shown in Table 2.

[0039] Table 2. Concentrate thermal stability test results

[0040] It can be seen from the results in Table 2 that the concentrate prepared by the present invention has no obvious changes in the thermal stability test and has excellent stability; it can be seen from the results of Comparative Example 1 and Example 2 that the lack of antioxidants causes oxidation and deterioration of the oil under high temperature conditions, resulting in darkening of the color and the generation of sticky precipitates; it can be seen from the results of Comparative Example 3 and Example 2 that the lack of a stable three-dimensional thickening network constructed by hydroxypropyl methylcellulose causes an incomplete system, and obvious stratification occurs when placed at high temperature for a long time.

[0041] Accelerated aging test: The concentrated solutions prepared in Example 2 and Comparative Examples 1 to 3 were placed in an environment of 60°C and 80% humidity for 28 days. The pH values ​​of the concentrated solutions were measured and recorded on the 3rd, 7th, 14th and 28th days. The results are as follows: Figure 2 shown.

[0042] Depend on Figure 2 The results show that the concentrated liquid prepared by the present invention can be stored stably for a long time and has excellent stability; from the results of Comparative Example 1 and Example 2, it can be seen that the lack of antioxidants makes the oil more easily oxidized, the acidic oxidation products accumulate faster, and the pH value decreases significantly; from the results of Comparative Example 3 and Example 2, it can be seen that the lack of hydroxypropyl methylcellulose makes the bio-based thickener system incomplete, the thermal stability and interfacial stability of the system are reduced, local hydrolysis and oxidation phenomena are obvious, and the pH value decreases significantly.

[0043] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A concentrated liquid for a zero-emission hydraulic support, characterized in that: The composition includes the following raw materials by weight: 65-80 parts of base oil, 2-5 parts of emulsifier, 1-2 parts of bio-based antioxidant, 5-12 parts of bio-based thickener, 0.01-0.02 parts of antifoaming agent and 4-6 parts of nano lubricant.

2. The concentrated liquid for zero-emission hydraulic support according to claim 1, characterized in that: The base oil comprises the following components in parts by weight: 30 to 35 parts of linseed oil, 30 to 35 parts of rapeseed oil and 5 to 10 parts of polycaprolactone.

3. The concentrated liquid for zero-emission hydraulic support according to claim 2, characterized in that: The emulsifier is any one of monolaurin, triglyceride, monolaurin and glyceryl palmitate.

4. The concentrated liquid for zero-emission hydraulic support according to claim 3, characterized in that: The foam suppressor is polydimethylsiloxane.

5. The concentrated liquid for zero-emission hydraulic support according to claim 4, characterized in that: The bio-based antioxidant is composed of the following raw materials in parts by weight: 0.3-0.5 parts of rosemary extract, 0.4-0.8 parts of tea polyphenols, 0.2-0.4 parts of alginic acid and 0.1-0.3 parts of citric acid.

6. The concentrated liquid for zero-emission hydraulic support according to claim 5, characterized in that: The bio-based thickener comprises hydroxypropyl guar gum, hydroxypropyl methylcellulose, chitosan and sodium alginate, and the specific preparation steps are as follows: A1: Add hydroxypropyl guar gum, hydroxypropyl methylcellulose and sodium alginate into deionized water respectively, heat, stir and dissolve evenly to obtain hydroxypropyl guar gum solution, hydroxypropyl methylcellulose solution and sodium alginate solution; add chitosan into deionized water, stir and mix evenly, adjust pH to obtain chitosan solution; A2: The hydroxypropyl guar gum solution, hydroxypropyl methylcellulose solution, chitosan solution and sodium alginate solution prepared in step A1 are added in sequence and stirred to mix evenly, ultrasonically treated, and CaCl2 solution is slowly added dropwise, the pH is adjusted, stirred, allowed to react, and vacuum dried to obtain a bio-based thickener.

7. The concentrated liquid for zero-emission hydraulic support according to claim 6, characterized in that: In step A2, the volume ratio of the hydroxypropyl guar gum solution, hydroxypropyl methylcellulose solution, chitosan solution and sodium alginate solution is 1:1:1:1; the amount of the CaCl2 solution is 1 to 1.5% of the volume of the substrate mixed solution.

8. The concentrated liquid for zero-emission hydraulic support according to claim 7, characterized in that: The nano-lubricant is graphene@SiO2-Al2O3 nanoparticles, and the specific preparation steps are as follows: B1: adding graphene to deionized water, performing ultrasonic treatment, and dispersing the graphene uniformly to obtain a graphene dispersion; adding ethyl silicate to anhydrous ethanol, stirring and mixing the mixture uniformly to obtain a silicon solution; B2: Slowly add the silicon solution prepared in step B1 into deionized water, then add hydrochloric acid to adjust the pH, stir and react to obtain silica sol; Aluminum isopropanol is added to anhydrous ethanol, the pH value is adjusted, and the mixture is stirred to obtain aluminum sol; silica sol and aluminum sol are mixed to obtain a mixed sol; B3: Mix the graphene dispersion prepared in step B1 with the mixed sol prepared in step B2, perform ultrasonic treatment, disperse evenly, control the temperature, stir the reaction, cool to room temperature, centrifuge, filter, and heat treat to obtain graphene@SiO2-Al2O3 nanoparticles.

9. The concentrated liquid for zero-emission hydraulic support according to claim 8, characterized in that: In step B1, the volume ratio of the ethyl silicate to anhydrous ethanol is 1:4-6; in step B2, the volume ratio of the silicon solution to deionized water is 1-1.5:1; the volume ratio of aluminum isopropanol to anhydrous ethanol is 1g:10-12mL; the volume ratio of the silica sol to the aluminum sol is 2-3:1; in step B3, the volume ratio of the graphene dispersion to the mixed sol is 1:

5.

10. The concentrated liquid for zero-emission hydraulic support according to claim 9, characterized in that: The preparation method comprises the following steps: S1: Mix linseed oil and rapeseed oil in the base oil evenly, then add polycaprolactone, increase the temperature, stir and mix thoroughly, then add bio-based antioxidant and emulsifier, stir and obtain oil phase; S2: adding the bio-based thickener to deionized water, increasing the temperature, stirring and dispersing uniformly, and obtaining a bio-based thickening solution; slowly adding the bio-based thickener to the oil phase prepared in step S1, increasing the temperature, stirring, and then increasing the speed and stirring to obtain an emulsified system; S3: Disperse the graphene@SiO2-Al2O3 nanoparticles in deionized water, disperse them evenly by ultrasonic treatment, and obtain a dispersion; add the dispersion and the antifoaming agent to the emulsified system prepared in step S2, heat, stir and mix evenly, then cool to room temperature, let stand, vacuum dry, adjust the pH, and obtain a concentrated solution.

Images