CN112625803B - A kind of preparation method of environment-friendly bio-based lubricating grease - Google Patents

Abstract

The invention discloses a preparation method of an environment-friendly bio-based grease. The environment-friendly bio-based grease, in parts by weight, comprises: 60-100 parts of a base grease, 20-40 parts of a thickener, and an antioxidant. 5-15 parts, 1-5 parts of extreme pressure agent and 1-5 parts of rust inhibitor, the base grease is a higher fatty acid ester prepared from kitchen waste oil, and the method for preparing higher fatty acid ester by using kitchen waste oil , including: purification of kitchen waste oil, catalytic hydrolysis, separation, two-stage distillation and esterification steps, wherein, in the catalytic hydrolysis step, a complex ionic liquid catalyst is used, and the mass fraction ratio of the catalyst to the kitchen waste oil is 1: (30‑50).

Description

A kind of preparation method of environment-friendly bio-based lubricating grease

technical field

The invention belongs to the technical field of fatty acid ester preparation, and in particular relates to a method for preparing higher fatty acid esters from kitchen waste oil and an environment-friendly bio-based lubricating grease containing the fatty acid esters.

Background technique

Kitchen waste oil generally refers to all kinds of inferior oils in life, which mainly come from greasy floating objects in sewers, garbage discharged from hotels and catering industries, waste oil from animal processing, and leftover oil after repeatedly frying food. The output of kitchen waste oil in my country is very large, and its direct discharge not only causes a huge waste of resources, but also has a huge impact on people's living environment. Therefore, how to fully tap and utilize the abundant kitchen waste oil resources and turn waste into treasure is an urgent problem that needs to be solved.

Grease is a grease-like semi-solid composed of base oil and thickener, which mainly plays the role of lubricating, protecting and sealing when mechanical parts are rubbed. Grease can be divided into vegetable oil, mineral oil and synthetic oil according to the base oil, and can be divided into lithium-based, calcium-based, sodium-based, composite-based and bentonite grease according to the thickener. Among them, biodegradable environment-friendly lubricating greases are based on rapidly biodegradable lubricating greases, which have a high biodegradation rate and are gradually attracting widespread attention.

CN1206332C discloses a kind of biodegradable lubricating grease, which comprises 70-94% vegetable oil, thickener bentonite and amine antioxidant or phenol and amine mixed antioxidant; CN100510031C discloses a kind of biodegradable lubricating grease, It includes vegetable oil, fatty acid lithium-calcium mixed soap, antioxidant and metal rust inhibitor, etc. CN111560278A discloses an environment-friendly composite aluminum-based lubricating ester and a preparation method thereof, which is obtained by hydrolysis and esterification of vegetable oil. Alcohol ester is used as base oil; CN105505546 discloses a preparation method of lubricating grease containing nano-rare earth oxide, wherein rapeseed oil or waste vegetable oil is used as base oil; CN102199471B discloses an environment-friendly lubricating grease composition, which comprises base oil Oil and lithium complex soap thickener, wherein the base oil is a mixed oil of modified vegetable oil and polyalphaolefin oil. Among the many studies on environmentally friendly greases, vegetable oils are basically the main ones, and there are fewer studies on the mixture of animal fat and vegetable oil as the base oil, especially the kitchen waste oil as the base oil for lubricating grease.

Therefore, using kitchen waste oil as the base oil component of lubricating grease, developing and researching environment-friendly lubricating grease is of great significance to make full use of kitchen waste oil resources and reduce environmental pollution.

SUMMARY OF THE INVENTION

One object of the present invention is to provide a method for preparing higher fatty acid esters from kitchen waste oil, which achieves substantially higher fatty acid ester products through the combination of ionic liquid catalysis and two-stage distillation, while avoiding strong acids or strong The erosion of the reaction vessel by the alkali solvent and the environmental pollution caused by the discharge of strong acid or strong alkali solution realize the full development and reuse of kitchen waste oil resources.

Another object of the present invention is to provide an environment-friendly bio-based lubricating grease, which uses kitchen waste oil as a basic raw material, realizes the maximum utilization of kitchen waste oil resources, has low manufacturing cost, simple method and easy mass production ; The compound of sulfurized fatty acid ester and inorganic borate is used as extreme pressure agent, and through the synergistic effect with antioxidant, thickener and rust inhibitor, the prepared grease has good wear resistance and extreme pressure. Capacitive and green effect.

The object of the present invention is achieved through the following technical solutions:

A method for preparing saturated higher fatty acid ester from kitchen waste oil, is characterized in that, comprises the steps:

A. Catalytic hydrolysis: place the pretreated kitchen waste oil in a reaction vessel, add water and an ionic liquid catalyst, heat and stir, and react for 3-4 hours;

b. Separation: cooling the kitchen waste oil after the catalytic hydrolysis to room temperature, leaving it to stand for layering to remove the lower mixed liquid, and obtaining the crude fatty acid in the upper layer;

c. The first distillation: under vacuum, the crude fatty acid is distilled in the temperature range of 210-230 ℃ to separate out the low-carbon fatty acid;

D. Second distillation: under vacuum, the remaining crude fatty acid after the first distillation is distilled again in the temperature range of 270-290 ° C, and the fractions are collected;

E. Esterification: The collected fractions are reacted with methanol or ethanol to generate fatty acid esters.

Wherein, the ionic liquid catalyst is a composite ionic liquid catalyst, and the mass ratio of the catalyst to the kitchen waste oil is 1:(30-50). Preferably, the mass ratio of the catalyst to the kitchen waste oil is 1:(35-45); more preferably, the mass ratio of the catalyst to the kitchen waste oil is 1:40.

Wherein, the complex ionic liquid catalyst is composed of a carboxyl-functionalized ionic liquid and a sulfonic acid-functionalized ionic liquid, preferably, the carboxyl-functionalized ionic liquid is selected from 1-carboxyethyl-3-methylimidazole nitrate , 1-carboxymethyl-3-methylimidazole nitrate, 1-carboxyethyl-3-methylimidazole chloride and 1-carboxymethyl-3-methylimidazole bis(trifluoromethanesulfonyl)imide one or more of the salts; and the sulfonic acid functionalized ionic liquid is selected from the group consisting of N-sulfonic acid butylpyridine p-toluenesulfonate, sulfonic acid butyl pyridine lactone, sulfonic acid propyl pyridine lactone, 1 - One or more of butylsulfonic acid-3-methylimidazole hydrogen sulfate and 1-butylsulfonic acid-3-methylimidazole trifluoroacetate.

Wherein, the mass fraction ratio of the carboxyl functionalized ionic liquid to the sulfonic acid functionalized ionic liquid is (1-3):1.

Preferably, the mass fraction ratio of the carboxyl-functional ionic liquid to the sulfonic acid-functional ionic liquid is (1.5-2.5): 1. More preferably, the ratio of the carboxyl-functional ionic liquid to the sulfonic acid-functional ionic liquid is (1.5-2.5): 1. The mass ratio is 2:1.

Wherein, under vacuum conditions, the first distillation is carried out in the temperature range of 210-230 ° C to separate low-carbon fatty acids; First distillation; more preferably, at 210°C, 212°C, 214°C, 216°C, 218°C, 220°C, 222°C, 224°C, 226°C, 228°C and 230°C or any range in between The first distillation is carried out at any value of temperature.

Wherein, under vacuum conditions, the second distillation is carried out in the temperature range of 270-290 ° C to separate most of the stearic acid; The second distillation is carried out at a temperature in the temperature range of 285°C; The second distillation is carried out at a temperature of °C or any value in any range therebetween.

Wherein, in this article, low-carbon fatty acids refer to fatty acids with carbon atoms ranging from 1 to 12; preferably, low-carbon fatty acids are carbon atoms ranging from 1 to 12, 2-11, 3-10, or 4-8 fatty acids within.

Herein, higher fatty acids refer to fatty acids having a carbon number in the range of 13 to 18.

Wherein, before the catalytic hydrolysis step, a purification step is also included. Wherein, the purification step includes: weighing the kitchen waste oil, centrifuging to remove suspended solids, adding an appropriate amount of water to remove colloidal substances, drying and dehydrating, adding activated clay with a mass of 1-5% of the kitchen waste oil, heating to 90- 120 ℃, stir evenly, keep the temperature for 1.5-2.0 hours, and decolorize the pretreated kitchen waste oil.

Wherein, in the catalytic hydrolysis step, the reaction is carried out at a reaction temperature of 90-150° C. for 3-4 hours.

Use of the saturated higher fatty acid ester prepared according to the above method in the preparation of industrial lubricating grease.

A preparation method of an environment-friendly bio-based lubricating grease, which comprises the saturated higher fatty acid ester prepared according to the above method.

Specifically, a method for preparing an environment-friendly bio-based grease, the environment-friendly bio-based grease, in parts by weight of the grease, comprises: 60-100 parts of a base grease, 20-40 parts of a thickener, 5-40 parts of an antioxidant 15 parts, 1-5 parts extreme pressure agent and 1-5 parts rust inhibitor.

Wherein, the base fat is the higher fatty acid ester prepared by the above method.

Wherein, the thickener is selected from one or more of random polypropylene, amorphous α-olefin copolymer, polymethacrylate bentonite, polyurethane and bentonite.

Wherein, the antioxidant is selected from p-,p-diisopropyldiphenylamine, N,N-diarylbutyl-p-phenylenediamine, bis-octyldiphenylamine, N-alkyl-α-naphthylamine, poly- One or more of trimethyldihydroquinoline and octylated diphenylamine.

Wherein, the extreme pressure agent is a composite of sulfurized fatty acid ester and inorganic borate nanoparticles. Wherein, the sulfurized fatty acid ester is selected from one or more of dimethyl dithiocarboxylate, distearyl thiodipropionate, sulfurized fatty acid methyl ester and thioethanol stearate ; The inorganic borate nanoparticles are selected from one or more of calcium borate nanoparticles, molybdenum borate nanoparticles, potassium borate nanoparticles and magnesium borate nanoparticles.

Wherein, the inorganic borate nanoparticles are chemically modified borate nanoparticles. Specifically, the inorganic borate nanoparticles are oleic acid or stearic acid modified borate nanoparticles.

Wherein, the chemical modification includes the following steps: dissolving inorganic borate in water, heating to 50-80° C., stirring for 30-50 minutes, adding solvent xylene and modifier oleic acid or stearic acid, heating to 80-110°C, fully stirring for 2-4 hours, stop the reaction, stand for stratification, and spray dry the organic layer at 100-120°C to obtain oleic acid or stearic acid-modified borate nanoparticles.

Wherein, the particle size of the nanoparticles is 50-500 nm, preferably, the particle size of the nanoparticles is 50, 100, 150, 200, 250, 300, 350, 400, 450, 500 nm or their Any value in any range in between.

Wherein, by weight, the mass fraction ratio of the sulfurized fatty acid ester and the inorganic borate is (1-3): 1, preferably, the mass fraction of the sulfurized fatty acid ester and the borate nanoparticles The ratio is (1-2):1; more preferably, the mass fraction ratio of the sulfurized fatty acid ester and the borate nanoparticles is 1.5:1.

Wherein, in parts by weight, the environment-friendly bio-based grease includes 60, 65, 70, 75, 80, 85, 90, 95, 100 parts of base grease or any value within any range therebetween.

Wherein, the kinematic viscosity of the base grease at 40° C. is 70-140 mm ² /s.

Wherein, in parts by weight, the grease includes 20, 22, 24, 26, 28, 30, 32, 34, 36, 38, 40 parts of the thickener or any value within any range therebetween.

Wherein, in parts by weight, the grease includes 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 parts of antioxidants or any value within any range therebetween.

Wherein, in parts by weight, the grease includes 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0 parts of extreme pressure agent or any value within any range therebetween.

Wherein, the rust inhibitor is selected from one or more of sorbitan trioleate, sorbitan monooleate, zinc sulfonate, calcium sulfonate, sodium petroleum sulfonate and barium petroleum sulfonate .

Wherein, by weight, the lubricating grease also includes 5-15 parts of eel mucus. Preferably, the grease further comprises 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 parts of eel mucus or any value within any range therebetween.

Eel mucus is a kind of substance rich in mucin and polysaccharide, among which mucin is a kind of highly glycosylated high molecular weight substance with gel forming ability, which has strong adhesion and is easy to adsorb and fix on metal. The surface of the part is used to repair the uneven parts on the surface that are invisible to the naked eye, thereby forming a film structure that is resistant to acid, oxidation and water vapor.

Wherein, the extraction method of the eel mucus comprises: placing the eel in a filter screen of 80-100 meshes, so that it is short of water and keeps wriggling, crowding each other to generate a large amount of mucus, the mucus flows into a container with oil-water separation function, and the collection is obtained. Eel mucus.

A method for preparing an environment-friendly bio-based lubricating grease, comprising: adding a base grease and a thickener into a reaction vessel, heating up to 50-80°C, fully stirring for 20-40 minutes, continuing to heat up to 120-160°C, and maintaining the temperature 5-8 minutes, stop heating, add antioxidant, extreme pressure agent and rust inhibitor, stir well, cool to room temperature, grind, filter and package.

Specifically, a preparation method of an environmentally friendly bio-based grease, comprising the following steps:

a) Add 60-100 parts of base grease and 20-40 parts of thickener into a reactor equipped with a heating device and a stirring device, heat it to 50-80°C, and stir at 300-500 r/min for 20- 40 minutes, until fully mixed;

b) Continue to heat up to 120-160°C and keep the temperature for 5-8 minutes;

c) Stop heating, add 5-15 parts of antioxidant, 1-5 parts of extreme pressure agent and 1-5 parts of rust inhibitor, and stir well;

d) Cool to room temperature, grind, filter and package.

Optionally, in step c), add 5-15 parts of eel mucus, and stir well.

Specifically, a preparation method of an environmentally friendly bio-based grease, comprising the following steps:

1) Catalytic hydrolysis: put the pretreated kitchen waste oil in a reaction vessel, add water and an ionic liquid catalyst, heat and stir, and react for 3-4 hours;

2) Separation: the kitchen waste oil after catalytic hydrolysis is cooled to room temperature, left to stand for layering to remove the lower mixed liquid, and the crude fatty acid of the upper layer is obtained;

3) The first distillation: under vacuum, the crude fatty acid is distilled in the temperature range of 210-230℃ to separate out the low-carbon fatty acid;

4) The second distillation: under vacuum, the remaining crude fatty acid after the first distillation is distilled again at the temperature range of 270-290℃, and the fractions are collected;

5) Esterification reaction: react the collected fractions with methanol or ethylene glycol to generate fatty acid esters;

6) Add 60-100 parts of fatty acid ester and 20-40 parts of thickener prepared in step 5) into a reactor equipped with a heating device and a stirring device, heat to 50-80 ° C, and heat at 300-500 r/ 20-40 minutes of recited stirring for 20-40 minutes, until fully mixed;

7) Continue to heat up to 120-160°C and keep the temperature for 5-8 minutes;

8) Add 5-15 parts of antioxidant, 1-5 parts of extreme pressure agent and 1-5 parts of rust inhibitor, stir well;

9) Cool to room temperature, grind, filter and package.

In the method, the base fat includes higher fatty acid esters derived from kitchen waste oil; specifically, the base fat includes the waste kitchen oil after catalytic hydrolysis, two-stage distillation and esterification. Oil; more specifically, the base fat is a higher fatty acid ester obtained by catalytic hydrolysis, two-stage distillation and esterification of kitchen waste oil.

In the described method, before the catalytic hydrolysis step, a purification step is also included. The purification step includes: weighing the kitchen waste oil, centrifuging to remove suspended solids, adding an appropriate amount of water to remove colloidal substances, drying and dehydrating, adding activated clay with a mass of 1-5% of the kitchen waste oil, and heating to 90-120° C. , stir evenly, keep the temperature for 1.5-2.0 hours, and decolorize the pretreated kitchen waste oil.

The environment-friendly bio-based lubricating grease of the present invention achieves the following technical effects:

(1) The preparation method for preparing higher fatty acid ester of the present invention has simple steps and convenient materials. Through the composite ionic liquid catalyst, two-stage distillation and esterification process, low-carbon fatty acid and higher fatty acid are successfully separated, and the traditional sulfuric acid catalyzed hydrolysis is reduced. Corrosion of the reaction vessel, and avoid the environmental pollution caused by the incomplete reaction of concentrated acid. At the same time, the inventor of the present invention unexpectedly found that the use of a complex ionic liquid catalyst composed of a carboxyl functionalized ionic liquid and a sulfonic acid functionalized ionic liquid can better match the molecular weight and structure of the waste kitchen oil. fatty acids for better overall separation.

(2) The environment-friendly bio-based lubricating grease of the present invention uses the kitchen waste oil that is ubiquitous in life as the main raw material, which provides a feasible way for the resource utilization of the kitchen waste oil and turning waste into treasure, thereby reducing Environmental pollution and human health problems caused by improper disposal of kitchen waste oil.

(3) The environment-friendly bio-based grease of the present invention uses biodegradable kitchen waste oil as the main raw material, and uses the higher fatty acid ester prepared from the kitchen waste oil and compound extreme pressure agent, antioxidant and rust inhibitor. combination to increase the synergistic effect between them. In addition, the present invention uses oleic acid or stearic acid-modified borate nanoparticles as thickening agent, which not only has good compatibility with the base grease to a certain extent, but also realizes the realization of the micro-sized nanoparticles in the base grease. Good dispersibility.

(4) The use of the sulfur-containing and boron-containing compound extreme pressure agent significantly improves the extreme pressure wear resistance of the grease of the present invention. It can act in the same way as metal elements on the surface of metal parts to generate sulfide metal film and boride metal film, which protect the workpiece from wear to a certain extent and improve the sealing between the two parts.

(5) In the grease of the present invention, the addition of eel mucilage makes a film with high viscosity and good waterproofness formed on the surface of the metal part, which not only improves the sealing and waterproofness of the grease, but also improves its performance. Pressure wear effect.

Detailed ways

The technical solutions of the present invention will be described in detail and completely below with reference to specific embodiments, however, those skilled in the art know that the described embodiments are only for the purpose of example, rather than the whole of the present invention. Based on the embodiments enumerated in the present invention, those of ordinary skill in the art will better understand and grasp the technical solutions claimed in the present invention and the technical effects achieved.

In this article, kitchen waste oil generally refers to all kinds of inferior oils in life, including oils from inferior meat processing and refining; residues and leftovers (commonly known as swill) from hotels, catering and other industries are simply processed and refined Oil produced; and edible oil from repeated frying, etc. Specifically, in this article, kitchen waste oil refers to waste oil with fatty acid glycerides as the main component, turbid and opaque appearance, wherein the moisture content of kitchen waste oil is higher than 1.0%, the acid value is higher than 5.0mgKOH/g, saponification Values above 250 mg/g and conductivity greater than 4 pS/m.

(1) Preparation of base esters

Preparation method 1: Preparation of base grease 1 of the present invention

(1) Purification: Weigh 1000 grams of kitchen waste oil, centrifuge to remove suspended solids, add an appropriate amount of water to remove colloidal substances, heat to about 200°C, stir, dry and dehydrate, cool, add about 40 grams of activated clay, heat to 110°C, stir evenly, keep warm for 2.0 hours, and decolorize;

(2) Catalytic hydrolysis: put the purified kitchen waste oil in a reaction vessel, add deionized water, stir, and then add 16 grams of 1-carboxyethyl-3-methylimidazole nitrate and 8 grams of 1- Butylsulfonic acid-3-methylimidazole hydrogen sulfate, slowly stirred, heated to a temperature of 125 ° C, and reacted for about 3 hours;

(3) Separation: cooling the kitchen waste oil after catalytic hydrolysis to room temperature, and leaving it to stand for layering to remove the lower mixed liquid to obtain the crude fatty acid in the upper layer;

(4) The first distillation: under vacuum, the crude fatty acid is distilled at a temperature of about 220 ° C to separate and remove low-carbon fatty acids;

(5) Second distillation: under vacuum, re-distill the remaining crude fatty acid after the first distillation at a temperature range of 280°C, condense the vapor escaping at high temperature, and collect fractions;

(6) Esterification reaction: the collected fractions were reacted with methanol at 60°C for 2.5 hours, distilled under reduced pressure to remove excess methanol, and dried under reduced pressure to generate fatty acid methyl esters, namely base fat 1 of the present invention.

Preparation method 2: Preparation of base grease 2 of the present invention

Except replacing 1-carboxyethyl-3-methylimidazole nitrate with 1-carboxyethyl-3-methylimidazolium chloride in the catalytic hydrolysis step (2) of Preparation Method 1, and replacing 1-butyl Except that sulfonic acid-3-methylimidazole hydrogen sulfate is replaced with sulfonic acid propylpyridine lactone, the remaining components, contents and operations are the same as those of preparation method 1.

Preparation method 3: preparation of base fat 3 of the present invention

Except replacing 16 grams of 1-carboxyethyl-3-methylimidazole nitrate in the catalytic hydrolysis step (2) in Preparation Method 1 with 18 grams of 1-carboxymethyl-3-methylimidazole nitrate, And replacing 8 grams of 1-butylsulfonic acid-3-methylimidazole hydrogen sulfate with 6 grams of 1-butylsulfonic acid-3-methylimidazole trifluoroacetate, the remaining components and contents And operation is the same as preparation method 1.

Preparation method 4: Preparation of base fat 4 of the present invention

The temperature of the first distillation was replaced by 220°C with 210°C and the temperature of the second distillation was replaced by 280°C with 270°C.

Preparation method 5: Preparation of base fat 5 of the present invention

Except that the temperature of the first distillation was replaced by 220°C with 230°C and the temperature of the second distillation was replaced by 280°C with 290°C, the rest of the components, contents and operations were the same as in Preparation Method 1.

Preparation Method 6: Preparation of Base Fat 6 for Comparison

In the catalytic hydrolysis step (2) in the preparation method 1, only 24 grams of 1-carboxyethyl-3-methylimidazolium nitrate was added as the ionic liquid catalyst, and the remaining components, contents and operations were the same as those in the preparation method 1.

Preparation method 7: Preparation of base fat 7 for comparison

In the catalytic hydrolysis step (2) in the preparation method 1, only 24 grams of 1-butylsulfonic acid-3-methylimidazole hydrogensulfate was added as the ionic liquid catalyst, and the remaining components and contents, operations and preparation method 1 same.

Preparation Method 8: Preparation of Base Fat 8 for Comparison

Except that the temperature of the second distillation was replaced by 280°C with 260°C, the remaining components, contents and operations were the same as those in Preparation Method 1.

Preparation method 9: Preparation of base fat 9 for comparison

Except that the first distillation and the second distillation are combined into distillation at a temperature of 260° C., the remaining components, contents and operations are the same as those of Preparation Method 1.

(2) Preparation of grease

The greases of Examples 1-11 and Comparative Examples 1-7 were prepared according to the following specific steps 1 and 2. The specific components and contents (by weight) of each grease are shown in Table 1 below, wherein each lubricating grease The fat also contains 10 parts of antioxidant octylated diphenylamine and 2 parts of rust inhibitor sorbitan trioleate.

Step 1: Dissolve the inorganic borate in water, heat it to 65°C, stir for 35 minutes, add xylene and oleic acid, heat up to 105°C, stir well for 2.5 hours, stop the reaction, stand for stratification, put the organic layer in Spray drying at 110 °C to obtain oleic acid-modified borate nanoparticles (extreme pressure agent).

Step 2: by weight, add the base grease and thickener into the reaction vessel, mix, heat up to 55°C, add an appropriate amount of acetone, stir well, then add antioxidants, sulfurized fatty acid esters and inorganic borate nanoparticles and Antirust agent, stirring and heating up to 100 ° C, constant temperature reaction for 6 hours, standing to cool, grinding to obtain lubricating grease.

Table 1

(2) Test indicators

GB/T3498 Grease Dropping Point Determination Method to determine the dropping point of lubricating grease; according to GB/T269-91 to determine the working penetration; according to GB/T12583-1998, to use the four-ball method to determine the maximum non-seizing load PB value (N); The wear scar diameters of the greases of the examples and comparative examples were tested using a four-ball friction and wear tester. The specific test results are shown in Table 2 below:

Table 2

From the measurement results in Table 2, it can be seen that the dropping point temperature of the grease is affected by factors such as thickeners and extreme pressure agents. The dropping point was the largest when the ratio of fatty acid sulfate and borate nanoparticles was 1.5:1; borate modification and application of fatty acid sulfate or borate alone had no significant effect on the dropping point. As the specific gravity of the thickener in the grease gradually increases, the dropping point temperature increases continuously. In addition, as shown in Comparative Examples 3-4, the one-time and low-temperature distillation increases the dropping point temperature of the grease, the reason may be that the lower temperature is not enough to separate C18 fatty acids such as stearic acid, oleic acid, carbon The drop in atomic number increases the dropping point temperature to some extent, and the wear scar diameter increases significantly.

Moreover, as shown in Comparative Examples 3-4, the reduction in distillation temperature and the reduction in the number of distillations significantly increased the working penetration of the grease. The reason may be that the lower temperature makes it difficult to separate long-chain higher fatty acids with more carbon atoms, The result of one distillation is that the separated fatty acids contain more low-carbon fatty acids, which make the grease produced softer and more penetrating. Extreme pressure agent type and modification affect penetration. In the grease, the relative increase of the thickener ratio reduces the penetration of the grease; and the addition of eel mucus reduces the penetration of the grease to a certain extent.

As shown in Examples 1, 6-7 and Comparative Examples 5-7, the compounding of extreme pressure agent makes the grease have a larger PB value, and the oleic acid modified borate makes the prepared grease have better performance Extreme pressure wear resistance and reduce wear of friction parts.

The performance of various indicators of the grease added with eel mucus is generally better than that of the grease without eel mucus. The reason may be that the eel mucus contains a large amount of mucin, which adheres to the surface of the part to form an adhesive layer with a certain viscosity and thickness And the O and S elements contained in it react with the metal bio-oxide or sulfide film, which can reduce the probability of the component being in contact with water vapor and oxygen in the air, thereby improving the wear-resistant extreme pressure performance of the grease.

As can be seen from Table 2 above, the comprehensive performance of the grease of the present invention is the result of the synergistic effect of base grease, thickener, extreme pressure agent and other additives.

The content of the present invention is not limited to the above-listed embodiments. Those skilled in the art should know that, without departing from the spirit and essence of the present invention, those skilled in the art can understand the technical characteristics of the present invention by reading the present invention. Various substitutions, modifications and combinations are made, and the technical solutions after the various modifications, substitutions and combinations are covered by the protection scope of the claims of the present invention.

Claims (12)

1. The preparation method of the environment-friendly bio-based lubricating grease comprises the following steps of: 60-100 parts of base grease, 20-40 parts of thickening agent, 5-15 parts of antioxidant, 1-5 parts of extreme pressure agent and 1-5 parts of antirust agent, wherein the base grease is higher fatty acid ester prepared from kitchen waste oil, and the method for preparing the higher fatty acid ester from the kitchen waste oil is characterized by comprising the following steps:

A. catalytic hydrolysis: placing the pretreated kitchen waste oil into a reaction vessel, adding water and an ionic liquid catalyst, heating and stirring, and reacting for 3-4 hours;

B. separation: cooling the kitchen waste oil subjected to catalytic hydrolysis to room temperature, standing for layering, and removing the lower mixed liquid to obtain an upper crude fatty acid layer;

C. first distillation: distilling the crude fatty acid at a temperature ranging from 210 ℃ to 230 ℃ under vacuum to separate a lower fatty acid;

D. and (3) second distillation: redistilling the remaining crude fatty acid after the first distillation at a temperature in the range of 270 ℃ and 290 ℃ under vacuum to separate most of the stearic acid;

E. esterification reaction: reacting the collected fraction with methanol or ethanol to produce fatty acid ester;

the ionic liquid catalyst is a compound of carboxyl functionalized ionic liquid and sulfonic acid functionalized ionic liquid, and the mass part ratio of the carboxyl functionalized ionic liquid to the sulfonic acid functionalized ionic liquid is (1-3): 1.

2. the preparation method of the environment-friendly bio-based lubricating grease as claimed in claim 1, wherein the mass part ratio of the catalyst to the kitchen waste oil is 1: (30-50).

3. The method for preparing environment-friendly bio-based grease according to claim 1, wherein the carboxyl-functionalized ionic liquid is selected from one or more of 1-carboxyethyl-3-methylimidazole nitrate, 1-carboxymethyl-3-methylimidazole nitrate, 1-carboxyethyl-3-methylimidazole chloride salt, and 1-carboxymethyl-3-methylimidazolium bis (trifluoromethanesulfonyl) imide salt; the sulfonic acid functionalized ionic liquid is selected from one or more of N-butyl pyridine sulfonate p-toluenesulfonate, butyl pyridine sultone, propyl pyridine sultone, 1-butyl sulfonic acid-3-methylimidazole bisulfate and 1-butyl sulfonic acid-3-methylimidazole trifluoroacetate.

4. The method for preparing the environment-friendly bio-based lubricating grease as claimed in claim 1, wherein the mass part ratio of the carboxyl functionalized ionic liquid to the sulfonic acid functionalized ionic liquid is (1.5-2.5): 1.

5. the method for preparing environment-friendly bio-based grease as claimed in claim 1, wherein the crude fatty acid is subjected to the first distillation at a temperature within the range of 215-225 ℃ under vacuum.

6. The method for preparing environment-friendly bio-based grease as claimed in claim 1, wherein the residual crude fatty acid after the first distillation is subjected to the second distillation at a temperature within the range of 275 ℃ and 285 ℃ under vacuum.

7. The method for preparing environment-friendly bio-based grease according to claim 1, further comprising a purification step before the catalytic hydrolysis step.

8. The method for preparing environment-friendly bio-based lubricating grease as claimed in claim 7, wherein the purification step comprises weighing kitchen waste oil, centrifuging to remove suspended matters, adding water to remove colloidal substances, drying, adding activated clay, heating to 90-120 ℃, stirring uniformly, keeping the temperature for 1.5-2.0 hours, and decolorizing to obtain the pretreated kitchen waste oil.

9. The method for preparing environment-friendly bio-based grease according to claim 1, wherein in the step of catalytic hydrolysis, the reaction is carried out at a reaction temperature of 90-150 ℃ for 3-4 hours.

10. The method for preparing environment-friendly bio-based grease according to claim 1, wherein the thickener is one or more selected from atactic polypropylene, amorphous alpha-olefin copolymer, polymethacrylate bentonite, polyurethane and bentonite.

11. The method for preparing environment-friendly bio-based grease according to claim 1, wherein the antioxidant is selected from one or more of p, p-diisopropyldiphenylamine, N-diarylbutylp-phenylenediamine, dioctyldiphenylamine, N-alkyl-alpha-naphthylamine, polytrimethyldihydroquinoline and octylated diphenylamine.

12. The method for preparing environment-friendly bio-based grease according to claim 1, wherein the extreme pressure agent is a composite of sulfurized fatty acid ester and inorganic borate nanoparticles.