A biocompatible and biodegradable emulsion gel lubricant and preparation and application thereof

Abstract

The present application belongs to the field of lubricating emulsion gel, and relates to a biocompatible and biodegradable emulsion gel lubricant and preparation and application thereof.Chitin is dissolved in acetic acid aqueous solution to obtain a chitin solution, a synthetic lubricating ester is added, the emulsion is homogenized to obtain a chitin emulsion, and then an alkali solution is used to control the pH value, so that the emulsion gel lubricant is obtained.The present application controls the electrostatic and hydrogen bond interaction forces between chitin molecules in the emulsion, realizes the gelation of chitin molecules, adds the synthetic ester to improve the lubricating performance and high load capacity of the emulsion gel, and the emulsion gel not only has excellent lubricating performance, but also has good biocompatibility and biodegradability.

Description

Technical Field

[0001] This invention belongs to the field of lubricating emulsion gels, and specifically relates to a biocompatible and biodegradable emulsion gel lubricant and its preparation and application. Background Technology

[0002] Lubricants play a vital supporting role in the development of the national economy, national defense, and related high-tech industries. They reduce friction and wear between two relatively moving contact surfaces and are indispensable for the operation of any machinery.

[0003] Currently, lubricants can be classified into four main categories based on their state of existence: gaseous lubricants, liquid lubricants, semi-solid lubricants, and solid lubricants. Liquid lubricants are the most widely used type, with mineral oil-based lubricants being the most common. However, mineral oil-based lubricants are prone to leakage, creep, and evaporation losses during friction and wear, which not only cause environmental pollution and waste but also lead to lubrication failure.

[0004] Green lubrication technology is a lubrication technology that reduces wear, saves energy, is recyclable, and does not harm the environment. To prevent the production of lubricating oil from negatively impacting the environment and generating biotoxic substances, researchers have been continuously working to research and develop environmentally friendly lubricants. Vegetable oil-based lubricants, prepared from vegetable oils, have excellent lubrication properties and can be rapidly decomposed into CO2 and H2O by microorganisms, making them non-toxic and biodegradable green lubricants. However, vegetable oil-based lubricants have poor anti-wear properties, load-bearing capacity, and oxidation resistance, limiting their application in industrial production. With the rapid development of modern industry and the increasing prominence of environmental issues, synthetic ester lubricants are attracting more and more attention, especially those with excellent lubricity, thermal stability, anti-wear and friction-reducing properties, high load-bearing capacity, high biodegradability, and low toxicity, which have become excellent candidate materials for the preparation of green lubricants. For example, CN107722952A discloses a synthetic ester lubricant for water-based drilling fluids and a water-based drilling fluid, wherein the lubricant contains a synthetic ester and an organosilicon; the synthetic ester is a product obtained by esterification of a C10-C18 single organic acid with an alcohol. However, due to the good fluidity of liquid lubricants, lubrication failure is easily caused during friction.

[0005] Chitosan is a product of the natural polysaccharide chitin, which has undergone partial acetyl group removal. It possesses multiple functions including biodegradability, biocompatibility, non-toxicity, and antibacterial properties, and is widely used in food additives, textiles, agriculture, environmental protection, and beauty and health care. There are also numerous reports on its use as an additive in lubricants. For example, CN109810750A uses chitosan phosphate esters and amine salt compounds as a lubricant composition, combined with isopropyl myristate, oleyl alcohol, fatty alcohol polyoxyethylene ether, and organomolybdenum to prepare an environmentally friendly micro-lubricant. CN103725392A and CN108504430A use hydroxymethyl chitosan as a component in the preparation of environmentally friendly emulsified cutting fluids. CN108048168A uses chitosan polyethylene glycol fatty acid esters as a component in an environmentally friendly biodegradable micro-cutting fluid, meeting the requirements for lubrication and cooling, extreme pressure anti-wear, and rust prevention in metal processing. CN108559591A uses chitosan as a component in the preparation of lubricant compositions. However, some of the aforementioned lubricant technologies containing chitosan components are still in a liquid state, which has the drawbacks of liquid lubricants; others have too many components and are too complex in composition.

[0006] Emulsion gel lubricants, as a type of semi-solid lubricant, possess characteristics such as low leakage and good sealing properties. They can solve problems such as leakage, creep, and localized failure caused by flow during friction and wear processes associated with liquid lubricants. Furthermore, emulsion gel lubricants offer advantages such as ease of storage and handling. Therefore, designing and preparing emulsion gel lubricants that combine biocompatibility, biodegradability, and excellent lubrication performance is of great significance for the development of green lubrication technology.

[0007] Currently, there are no reports on the preparation of biocompatible, degradable, and simple emulsion gel lubricants by combining chitosan and synthetic esters. Therefore, this invention is proposed. Summary of the Invention

[0008] In view of the aforementioned state of the prior art, the inventors of this invention conducted in-depth and extensive research in the field of emulsion gel lubricants, discovering that when chitosan and synthetic esters are combined, the electrostatic interactions between chitosan molecules reach equilibrium and the intermolecular hydrogen bonding is enhanced at a pH of 6-7, thereby forming cross-links. This allows for the formation of a stable emulsion gel with the synthetic ester, which not only possesses biocompatibility, biodegradability, and excellent lubricating properties, but also exhibits good leakage resistance and sealing performance. It can solve problems such as leakage, creep, and localized failure caused by flow during the friction and wear process of liquid lubricants, and also has advantages such as ease of storage and handling. This invention is based on the above discoveries.

[0009] Therefore, one object of the present invention is to provide an emulsion gel lubricant that not only has good biocompatibility and biodegradability, but also good lubrication performance. This lubricant is a semi-solid lubricant, characterized by its resistance to leakage and good sealing properties, which can solve problems such as leakage, creep, and localized failure caused by flow during the friction and wear process of liquid lubricants, and is also easy to store and handle.

[0010] A second objective of this invention is to provide a method for preparing the aforementioned emulsion gel lubricant. Utilizing the characteristic that the electrostatic interactions between chitosan molecules reach equilibrium and intermolecular hydrogen bonding is enhanced at a pH of 6-7, thereby forming cross-links, a stable emulsion gel is formed with the synthetic ester. This method is not only simple in composition but also convenient to prepare.

[0011] A third object of the present invention is to provide the use of the above-mentioned chitosan synthetic ester emulsion gel as a lubricant.

[0012] The technical solution for achieving the above-mentioned objectives can be summarized as follows:

[0013] Emulsion gel lubricant, which is an emulsion gel formed from chitosan solution and synthetic ester, pH=6-7.

[0014] According to the present invention, preferably, the oil-water volume ratio of the emulsion gel is 0.4:1 to 1.4:1, and most preferably 1:1.

[0015] According to the present invention, preferably, the concentration of chitosan in the emulsion gel is 0.05 wt% to 4 wt%.

[0016] According to the present invention, preferably, the volume fraction of the synthetic ester in the emulsion gel is 40% to 60%.

[0017] According to the present invention, preferably, the synthetic ester is one of pentaerythritol oleate and trimethylolpropane oleate.

[0018] According to the present invention, preferably, a multifunctional friction and wear testing machine is used to test the tribological properties of the lubricant, in a ball-disc point contact reciprocating mode, a steel ball with a diameter of 10 mm is selected for the friction pair, the load used is 15 N, the test frequency is 20 Hz, and the coefficient of friction of the lubricant is 0.04 to 0.05.

[0019] According to the present invention, preferably, the experimental system is prepared using fermented organic fertilizer and chitosan emulsion gel as raw materials, and the biodegradation rate is determined according to GB / T 19277.1-2011. The biodegradation rate of the lubricant after 45 days is more than 80%.

[0020] According to the present invention, the preparation method of the above-mentioned emulsion gel lubricant includes the following steps:

[0021] Chitosan is dissolved in an aqueous solution of acid to obtain a chitosan solution; the chitosan solution is added to a synthetic ester and emulsified and homogenized, and then the pH is adjusted to 6-7 to obtain a chitosan emulsion gel lubricant.

[0022] According to the present invention, preferably, the aqueous solution of the acid is an aqueous solution of acetic acid; preferably, the concentration of the aqueous solution of acetic acid is 1-3 vol%.

[0023] According to the present invention, preferably, the dissolution temperature of chitosan is 20–60°C.

[0024] According to the present invention, preferably, the concentration of the chitosan solution is 0.5 wt% to 6 wt%.

[0025] According to the present invention, preferably, after adding the chitosan solution to the synthetic ester, the volume fraction of the synthetic ester is 40% to 60%.

[0026] According to the present invention, preferably, the emulsification and homogenization process is carried out by magnetic stirring, with a stirring speed of 500-2000 rpm and a stirring time of 10-60 min.

[0027] According to the present invention, preferably, an alkaline solution is used to adjust the pH, and the preferred alkaline is one or two of sodium hydroxide, potassium hydroxide, and ammonia water, with a concentration of 1 to 20 mol / L.

[0028] According to the present invention, the above-described emulsion gel formed from chitosan solution and synthetic ester is used as a lubricant.

[0029] The beneficial effects of this invention are as follows:

[0030] 1. The emulsion gel lubricant of this invention is biocompatible and biodegradable, belonging to the category of environmentally friendly lubricants. An experimental system was prepared using fermented organic fertilizer and chitosan emulsion gel as raw materials. The biodegradation rate was determined according to GB / T 19277.1-2011, and the biodegradation rate of the lubricant reached over 80% after 45 days.

[0031] 2. The emulsion gel lubricant of the present invention has good lubrication performance. The tribological properties of the lubricant are tested using a multi-functional friction and wear testing machine in a ball-disc point contact reciprocating mode. The friction pair uses a steel ball with a diameter of 10 mm, the load is 15 N, the test frequency is 20 Hz, and the friction coefficient of the lubricant is 0.04 to 0.05.

[0032] 3. The emulsion gel lubricant of the present invention is a semi-solid lubricant with the characteristics of not being easy to lose and having good sealing properties. It can solve the problems of leakage, creep and local failure caused by flow of liquid lubricants in the process of friction and wear, and is easy to store and store.

[0033] 4. The emulsion gel lubricant of this invention utilizes the characteristic that the electrostatic interaction between chitosan molecules reaches equilibrium and the intermolecular hydrogen bonding is enhanced when the pH is between 6 and 7, thereby forming a cross-link, and forming a stable emulsion gel with the synthetic ester. It is not only simple in composition, non-toxic, and biodegradable, but also convenient to prepare. Attached Figure Description

[0034] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. Exemplary embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0035] Figure 1 (AC) are photographs of chitosan / pentaerythritol oleate emulsion gels of different concentrations in Examples 1-3 of the present invention, respectively;

[0036] Figure 2 The graphs show the coefficient of friction of chitosan / pentaerythritol oleate emulsion gels of different concentrations as a function of time in Examples 1-3.

[0037] Figure 3 This is Example 2 of the present invention, which describes the effect of chitosan / pentaerythritol oleate emulsion gels of different concentrations on the activity of mouse fibroblasts.

[0038] Figure 4 This is a graph showing the biodegradation rate of chitosan / pentaerythritol oleate emulsion gel over time in Example 2 of the present invention.

[0039] Figure 5 This is a photograph of the chitosan / trimethylolpropane oleate emulsion gel in Example 4 of the present invention. Detailed Implementation

[0040] This invention provides a biocompatible and biodegradable emulsion gel lubricant, its preparation method and application, wherein the emulsion gel lubricant comprises chitosan and synthetic esters.

[0041] Chitosan possesses biodegradability, biocompatibility, non-toxicity, and antibacterial properties. The main component of chitosan, the D-amino group, represents the hydrophilic portion, while the N-acetyl group represents the hydrophobic portion. This heterogeneity allows chitosan to adsorb at the oil-water interface, providing mechanical and electrostatic resistance. At low pH levels, due to the protonation of its amino groups, chitosan exhibits cationic properties, and the increased electrostatic repulsion between chitosan molecules prevents cross-linking. When pH 6 ≤ pH ≤ 7, the amino groups of chitosan become deprotonated, reducing surface charge. The electrostatic interactions between chitosan molecules reach equilibrium, and intermolecular hydrogen bonding strengthens, leading to cross-linking. At higher pH levels, chitosan molecules in solution form aggregates / precipitates.

[0042] Synthetic esters possess excellent lubricity, anti-wear properties, and load-bearing capacity. They are non-toxic and have a high biodegradability rate. Therefore, the resulting emulsion gel lubricant exhibits biocompatibility, biodegradability, and excellent lubrication performance. The chitosan emulsion gel lubricant of this invention is characterized by its resistance to leakage and good sealing properties, which can solve problems such as leakage, creep, and localized failure caused by flow during the friction and wear process of liquid lubricants. Furthermore, it has advantages such as ease of storage and handling.

[0043] The present invention relates to an emulsion gel lubricant, which is an emulsion gel formed from chitosan solution and synthetic ester, with a pH of 6 to 7.

[0044] According to the present invention, when 6≤pH≤7, the amino groups of chitosan become deprotonated, the surface charge decreases, the electrostatic interaction between chitosan molecules reaches equilibrium and the intermolecular hydrogen bonding is enhanced, thereby forming crosslinks, and can also form a stable emulsion gel system with synthetic esters.

[0045] In one or more preferred embodiments, the oil-water volume ratio of the emulsion gel is from 0.4:1 to 1.4:1, for example: 0.6:1, 0.8:1, 1:1, 1.2:1, with 1:1 being the most preferred.

[0046] According to the present invention, increasing the concentration of chitosan in the emulsion gel can reduce the friction coefficient of the lubricant, but it should not be too high. When it exceeds 4 wt%, the viscosity increases rapidly with the increase of chitosan concentration, which makes it impossible to form a uniform and stable chitosan emulsion gel during the mixing process with the synthetic ester, thereby affecting its lubrication performance.

[0047] In one or more preferred embodiments, the concentration of chitosan in the emulsion gel is 0.05 wt% to 4 wt%.

[0048] According to the present invention, the synthetic esters exhibit excellent lubricity, anti-wear properties, and load-bearing capacity, are non-toxic, and have a high biodegradability. Any synthetic ester that meets the requirements of good lubricity, high load-bearing capacity, non-toxicity, and biodegradability can be used in the present invention. Preferably, the synthetic esters are non-toxic, biocompatible, and biodegradable, with a degradation rate of 80% or higher.

[0049] In one or more preferred embodiments, the synthetic ester is one of pentaerythritol oleate and trimethylolpropane oleate.

[0050] The volume fraction of synthetic esters has a significant impact on the stability of emulsion gels. When the volume fraction of synthetic esters is too high or too low, the stability of the prepared chitosan emulsion gel will decrease. Within a short period of time, the oil phase will precipitate from the emulsion gel, resulting in phase separation and making it impossible to maintain the gel state.

[0051] In one or more preferred embodiments, the volume fraction of the synthetic ester in the emulsion gel is 40% to 60%.

[0052] According to the present invention, a method for preparing an emulsion gel lubricant includes the following steps:

[0053] (1) Dissolve chitosan powder in an aqueous acetic acid solution to obtain a chitosan solution;

[0054] (2) The chitosan solution is added to the synthetic ester and the emulsion is homogenized under magnetic stirring to obtain a chitosan emulsion;

[0055] (3) The chitosan emulsion is acidified to pH 6-7 using an alkaline solution to obtain a chitosan emulsion gel with biocompatibility and biodegradability.

[0056] In this invention, the chitosan used is commercially available chitosan with a degree of deacetylation ≥80%; the acetic acid is analytical grade with a concentration ≥99.5%.

[0057] In one or more preferred embodiments, acetic acid is prepared into an aqueous solution with a concentration of 1-3 vol%, preferably 2 vol%. Chitosan powder is added to the 2 vol% aqueous solution of acetic acid and magnetically stirred at a temperature of 20-60°C at a stirring speed of 100-1000 rpm for 2-8 hours. The free amino groups on the chitosan molecular chain are protonated in the acidic medium, generating a strong electrostatic repulsion, thereby causing it to dissolve into a uniform and transparent chitosan solution with a concentration of 0.5-6 wt%, preferably 4 wt%.

[0058] In this invention, a synthetic ester is added to a chitosan solution, wherein the synthetic ester is one of pentaerythritol oleate and trimethylolpropane oleate.

[0059] In one or more preferred embodiments, the synthetic ester accounts for 40-60% of the total solution volume fraction, preferably 50%. The chitosan concentration in the mixed solution is 0.05-4 wt%, preferably 1 wt%. The mixed solution is magnetically stirred at room temperature at a stirring speed of 500-2000 rpm, preferably 1500 rpm; the stirring time is 10-60 min, preferably 30 min, ultimately obtaining a uniform and white chitosan emulsion.

[0060] In this invention, an alkaline solution is used to adjust the pH value of the emulsion gel.

[0061] In one or more preferred embodiments, the alkaline solution is one or two of sodium hydroxide, potassium hydroxide, and ammonia water, and the concentration of the prepared alkaline solution is 1 to 20 mol / L, preferably 10 mol / L.

[0062] Under magnetic stirring, the prepared alkaline solution is added dropwise to the chitosan emulsion. The pH of the emulsion is tested with a pH meter during the addition until the pH reaches 6-7. At this point, the addition of the alkaline solution is stopped, and stirring continues for 5-30 minutes. The addition of the alkaline solution deprotonates the amino groups of the chitosan molecules, reducing their surface charge. This balances the electrostatic interactions between chitosan molecules and enhances intermolecular hydrogen bonding, leading to cross-linking and resulting in a uniform, stable, and white chitosan emulsion gel. When a small amount of alkaline solution is added, the pH of the chitosan emulsion is below 6. Due to the protonation of the amino groups in the chitosan molecules, they possess cationic properties, and the increased electrostatic repulsion between molecules prevents cross-linking, maintaining the emulsion state. When a large amount of alkaline solution is added, the pH of the chitosan emulsion is above 7. The increased electrostatic interactions between chitosan molecules easily lead to the formation of aggregates / precipitates, making it impossible to obtain a uniform and stable chitosan emulsion gel.

[0063] According to the present invention, the above-described emulsion gel formed from chitosan solution and synthetic ester is used as a lubricant.

[0064] The following detailed description of the preparation method of a biocompatible and biodegradable emulsion gel lubricant provided by the present invention, with reference to the embodiments, should not be construed as limiting the scope of protection of the present invention.

[0065] In the following examples, the storage modulus and loss modulus of the emulsion gel were measured using an MCR-302e rheometer (Anton Paar, Austria) at a constant strain of 0.1% within a frequency scanning range of 0.1-10 Hz.

[0066] The tribological properties of the prepared emulsion coagulation were characterized using a multifunctional triboelectric testing machine (UMT-TRIBOLAB, Brucker), employing a ball-disc point contact reciprocating mode. A 10 mm diameter steel ball was selected as the friction pair. The load used was 15 N, and the experimental frequency was 20 Hz. Before the experiment, the friction pair balls were ultrasonically cleaned for 10 min using ethanol and deionized water.

[0067] Cell cytotoxicity analysis of mouse fibroblasts was performed using the Cell Counting Kit-8 (CCK-8). Different concentrations of chitosan emulsion gel were added to the wells, with untreated cells serving as a control. 0.10 mL of CCK-8 diluted 10-fold with PBS was added to each well, and the cells were incubated at 37°C for 2 hours. The relative cell viability was calculated by measuring the absorbance at 450 nm using a microplate reader.

[0068] Biodegradation was determined according to GB / T 19277.1-2011. Chitosan emulsion gel was used as the experimental material. The culture soil (well-rotted organic fertilizer) and chitosan emulsion gel were mixed at a weight ratio of approximately 6:1 to prepare the sample experimental system. Chitosan emulsion gel was used as the organic carbon source, and the experimental mixture was aerated with carbon dioxide-free air at a controlled rate. The degradation rate was determined by measuring the amount of carbon dioxide produced.

[0069] Example 1

[0070] The preparation of emulsion gel lubricants includes the following steps:

[0071] (1) Use a pipette to measure 600 μL of acetic acid and add it to 28.2 g of ultrapure water. Stir magnetically to mix it evenly. Then weigh 1.2 g of chitosan powder and add it to the above solution. Stir magnetically for 5 h at 40°C and 500 rpm to form a uniform and transparent chitosan solution.

[0072] (2) Weigh 0.361g of the chitosan solution in (1) and add it to 2.315g of pentaerythritol oleate. Add 2.1g of ultrapure water to the above mixed solution. Stir magnetically at 1500rpm for 30min at room temperature to obtain a uniform and white chitosan / pentaerythritol oleate emulsion.

[0073] (3) Weigh 4g of sodium hydroxide and add it to 10mL of ultrapure water to prepare a sodium hydroxide aqueous solution with a concentration of 10mol / L;

[0074] Measure 10 μL of sodium hydroxide solution and add it dropwise to the chitosan / pentaerythritol oleate emulsion in step (2). Stir magnetically at 1500 rpm for 15 min at room temperature to obtain a uniform, white chitosan / pentaerythritol oleate emulsion gel with a chitosan concentration of 0.3 wt%, pH 6.4, and an oil-to-water volume ratio of 1:1. (Image of the emulsion gel is shown below.) Figure 1 As shown in Figure A.

[0075] Example 2

[0076] The preparation of emulsion gel lubricants includes the following steps:

[0077] (1) Use a pipette to measure 600 μL of acetic acid and add it to 28.2 g of ultrapure water. Stir magnetically to mix it evenly. Then weigh 1.2 g of chitosan powder and add it to the above solution. Stir magnetically for 5 h at 40°C and 500 rpm to form a uniform and transparent chitosan solution.

[0078] (2) Weigh 1.685g of the chitosan solution in (1) and add it to 3.241g of pentaerythritol oleate. Add 1.82g of ultrapure water to the above mixed solution. Stir magnetically at 1500rpm for 30min at room temperature to obtain a uniform and white chitosan / pentaerythritol oleate emulsion.

[0079] (3) Weigh 4g of sodium hydroxide and add it to 10mL of ultrapure water to prepare a sodium hydroxide aqueous solution with a concentration of 10mol / L;

[0080] 60 μL of sodium hydroxide solution was added dropwise to the chitosan / pentaerythritol oleate emulsion in step (2). The mixture was magnetically stirred at 1500 rpm for 15 min at room temperature to obtain a uniform, white chitosan / pentaerythritol oleate emulsion gel with a chitosan concentration of 1 wt%, a pH of 7, and an oil-to-water volume ratio of 1:1. A photograph of the emulsion gel is shown below. Figure 1 As shown in B.

[0081] Example 3

[0082] The preparation of emulsion gel lubricants includes the following steps:

[0083] (1) Use a pipette to measure 600 μL of acetic acid and add it to 28.2 g of ultrapure water. Stir magnetically to mix it evenly. Then weigh 1.2 g of chitosan powder and add it to the above solution. Stir magnetically for 5 h at 40°C and 500 rpm to form a uniform and transparent chitosan solution.

[0084] (2) Weigh 2.408g of the chitosan solution in (1) and add it to 2.315g of pentaerythritol oleate. Add 0.12g of ultrapure water to the above mixed solution. Stir magnetically at 1500rpm for 30min at room temperature to obtain a uniform and white chitosan / pentaerythritol oleate emulsion.

[0085] (3) Weigh 4g of sodium hydroxide and add it to 10mL of ultrapure water to prepare a sodium hydroxide aqueous solution with a concentration of 10mol / L;

[0086] 70 μL of sodium hydroxide solution was added dropwise to the chitosan / pentaerythritol oleate emulsion in step (2). The mixture was magnetically stirred at 1500 rpm for 15 min at room temperature to obtain a homogeneous, white chitosan / pentaerythritol oleate emulsion gel with a chitosan concentration of 2 wt%, a pH of 6.5, and an oil-to-water volume ratio of 1:1. A photograph of the emulsion gel is shown below. Figure 1 As shown in C.

[0087] Example 4

[0088] The preparation of emulsion gel lubricants includes the following steps:

[0089] (1) Use a pipette to measure 600 μL of acetic acid and add it to 28.2 g of ultrapure water. Stir magnetically to mix it evenly. Then weigh 1.2 g of chitosan powder and add it to the above solution. Stir magnetically for 5 h at 40°C and 500 rpm to form a uniform and transparent chitosan solution.

[0090] (2) Weigh 1.685g of the chitosan solution in (1) and add it to 3.15g of trimethylolpropane oleate. Add 1.82g of ultrapure water to the above mixed solution. Stir magnetically at 1500rpm for 30min at room temperature to obtain a uniform and white chitosan / trimethylolpropane oleate emulsion.

[0091] (3) Weigh 4g of sodium hydroxide and add it to 10mL of ultrapure water to prepare a sodium hydroxide aqueous solution with a concentration of 10mol / L;

[0092] 58 μL of sodium hydroxide solution was added dropwise to the chitosan / trimethylolpropane oleate emulsion in step (2). The mixture was magnetically stirred at 1500 rpm for 15 min at room temperature to obtain a uniform, white chitosan / trimethylolpropane oleate emulsion gel with a chitosan concentration of 1 wt%, a pH of 7, and an oil-to-water volume ratio of 1:1. A photograph of the emulsion gel is shown below. Figure 5 As shown.

[0093] Experimental Example 1

[0094] The coefficient of friction of the emulsion gels prepared in Examples 1-3 was tested, such as... Figure 2 As shown. By Figure 2 It can be seen that the coefficient of friction of the emulsion gel prepared in Example 1 is 0.05; the coefficient of friction of the emulsion gel prepared in Example 2 is 0.045; and the coefficient of friction of the emulsion gel prepared in Example 3 is 0.04.

[0095] It can be seen that the emulsion gel lubricant of the present invention has good lubrication performance.

[0096] Experimental Example 2

[0097] The chitosan / pentaerythritol oleate emulsion gel prepared in Example 2 was formulated into different concentrations, and its toxicity to mouse fibroblasts was then tested. Figure 3 As shown.

[0098] Depend on Figure 3 It is known that the chitosan / pentaerythritol oleate emulsion gel of the present invention has almost zero toxicity to mouse fibroblasts, and the survival rate of mouse fibroblasts is close to 100%. This indicates that the emulsion gel lubricant of the present invention has good biocompatibility.

[0099] Experimental Example 3

[0100] The biodegradability of the chitosan / pentaerythritol oleate emulsion gel prepared in Example 2 was tested, such as... Figure 4 As shown.

[0101] Depend on Figure 4 It is known that the biodegradation rate of the chitosan / pentaerythritol oleate emulsion gel of the present invention can reach 83.7% after 45 days. This indicates that the emulsion gel lubricant of the present invention has good biodegradability.

[0102] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. An emulsion gel lubricant, characterized in that, The lubricant is an emulsion gel formed from chitosan solution and synthetic ester, with a pH of 6-7; the concentration of chitosan in the emulsion gel is 0.05 wt% to 4 wt%, and the volume fraction of synthetic ester in the emulsion gel is 40% to 60%, wherein the synthetic ester is one of pentaerythritol oleate and trimethylolpropane oleate; Chitosan is dissolved in an aqueous solution of acid to obtain a chitosan solution; the chitosan solution is added to a synthetic ester and emulsified and homogenized, and then the pH is adjusted to 6~7 to obtain a chitosan emulsion gel lubricant, wherein the oil-water volume ratio of the emulsion gel is 0.4:1 to 1.4:

1.

2. The method for preparing the emulsion gel lubricant according to claim 1, comprising the following steps: Chitosan is dissolved in an aqueous solution of acid to obtain a chitosan solution; the chitosan solution is added to a synthetic ester and emulsified and homogenized, and then the pH is adjusted to 6~7 to obtain a chitosan emulsion gel lubricant.

3. The method for preparing the emulsion gel lubricant according to claim 2, characterized in that, The aqueous solution of the acid is an acetic acid aqueous solution with a concentration of 1-3 vol.

4. The method for preparing the emulsion gel lubricant according to claim 2, characterized in that, The dissolution temperature of chitosan is 20~60 ℃, and the concentration of chitosan solution is 0.5wt%~6 wt%.

5. The method for preparing the emulsion gel lubricant according to claim 2, characterized in that, After adding the chitosan solution to the synthetic ester, the volume fraction of the synthetic ester is 40%~60%.

6. The method for preparing the emulsion gel lubricant according to claim 2, characterized in that, The pH is adjusted using an alkaline solution, wherein the alkaline solution is one or two of sodium hydroxide, potassium hydroxide, and ammonia water.

7. Use of the emulsion gel formed from chitosan solution and synthetic ester as described in claim 1 as a lubricant.

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