Full-bio-based lubricating grease and preparation method thereof

Abstract

The invention discloses full-bio-based lubricating grease and a preparation method thereof, and the full-bio-based lubricating grease comprises the following components in parts by weight: 70-80 parts of base oil, 20-30 parts of a thickening agent and 0.1-1 part of an additive. The base oil is natural vegetable oil of different types, the thickening agent is prepared by taking biomass waste as a raw material, cellulose in the biomass waste is firstly extracted, then the extracted cellulose is subjected to isocyanate esterification modification, and finally the obtained modified fiber is the thickening agent. The full-bio-based lubricating grease prepared by the invention can effectively utilize biomass wastes in nature, and has the advantages of high biodegradability, environment friendliness, wide raw material source and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of lubricating materials, and in particular to a fully bio-based lubricating grease and a preparation method thereof. Background Art

[0002] Grease, as an important lubricant product, is mainly composed of base oil, thickener and additives. Traditional grease usually uses mineral oil or synthetic oil as base oil, most of which come from non-renewable petrochemical resources and will generate certain environmental loads during production and use. In addition, the currently used metal soap or polymer thickeners also have problems such as being difficult to degrade and harmful to the environment.

[0003] Therefore, the industry is in urgent need of a new technology for a fully bio-based grease and its preparation method. Summary of the invention

[0004] Based on this, the present invention proposes a fully bio-based grease, which uses vegetable oil as the base oil and cellulose extracted from biomass waste as the thickener. Compared with traditional grease, the fully bio-based grease has the advantages of being renewable, degradable, and having low carbon emissions, which meets the current social demand for green and environmentally friendly products.

[0005] To achieve the above object, the present invention provides a fully bio-based grease, which comprises the following raw materials in parts by mass: 70-80 parts of vegetable oil, 20-30 parts of thickener, and 0.1-1 part of additive; The thickener is made from biomass waste as raw material. The cellulose in the biomass waste is firstly extracted, and then the extracted cellulose is modified by isocyanate. The modified fiber finally obtained is the thickener.

[0006] Furthermore, the vegetable oil includes any one of soybean oil, castor oil, palm oil, coconut oil or rapeseed oil, or a combination of at least two of them.

[0007] Furthermore, the additive includes any one of an antioxidant, an extreme pressure agent and a rust remover, or a combination of at least two of them.

[0008] Further, the antioxidant includes any one or a combination of at least two of octylbutyldiphenylamine, diisooctyldiphenylamine, thiophenol antioxidants, p-methylphenol or tocopherol; The extreme pressure agent includes any one or a combination of at least two of calcium stearate, molybdenum di-n-butyl dithiocarbamate, zinc dialkylthiophosphate, borate or nano-grade zinc oxide; The rust remover comprises any one of medium-base calcium sulfonate, barium sulfonate or sodium sebacate, or a combination of at least two of them.

[0009] Furthermore, the thickener comprises the following preparation steps: S1. First pretreatment: Take an appropriate amount of biomass waste and add it to a mixed solution of toluene and ethanol, stir it at 80-120 °C for 4-8 h, cool it to room temperature, filter it and wash it with ethanol, and then dry it at 60-80 °C; S2. Second pretreatment: add the pretreated product in S1 to a 0.1-0.2 mol / L HCl solution, stir at 60-90 °C for 1-3 h, cool to room temperature, filter and wash with deionized water until neutral, and then dry at 60-80 °C; S3. Extraction of cellulose: The pretreated material in S2 was added to a mixture of 5-8% NaOH solution and 0.5-0.8% H2O2 solution by mass, stirred at 60-80°C for 2-3 h, cooled to room temperature, filtered, washed with deionized water until neutral, and then dried in a freeze dryer; S4. Modification of cellulose: Add the above cellulose, isocyanate and triethylamine to a toluene solution respectively, and react with stirring at room temperature for 24-48 h under a nitrogen atmosphere. After the reaction is completed, filter and wash with toluene for 3-5 times, and then dry at 60-80°C for 24 h to obtain a thickener.

[0010] Further, in step S1, the biomass waste includes any one or a combination of at least two of cotton stalks, corn stalks, wheat stalks, bean stalks, rice husks, peanut shells, coconut shells, sunflower husks, rice straw and sugarcane bagasse; In step S4, the isocyanate includes any one or a combination of at least two of diphenylmethane diisocyanate, toluene diisocyanate, dicyclohexylmethane diisocyanate, hexamethylene diisocyanate and isophorone diisocyanate.

[0011] Furthermore, in step S1, the ratio of toluene, ethanol and biomass waste is 50-80 mL: 20-40 mL: 5-15 g.

[0012] Furthermore, in step S2, the ratio of HCl solution to biomass waste is 100-200 mL: 5-15 g; and in step S3, the ratio of NaOH solution, H2O2 solution and biomass waste is 100 mL: 100 mL: 5-15 g.

[0013] Furthermore, in step S4, the ratio of toluene, cellulose, isocyanate and triethylamine is 100-200 mL: 10 g: 5-10 g: 0.5-1 g.

[0014] The present invention also provides a method for preparing the above-mentioned all-biobased grease, comprising the following steps: stirring a thickener and vegetable oil at 60-80°C to obtain a uniform mixture, then heating to 120-150°C for high-temperature expansion for 8-30 minutes, and finally adding additives and grinding using a three-roll grinder to obtain the all-biobased grease.

[0015] The present invention has the following beneficial effects: 1. The present invention provides a fully bio-based grease, which comprises the following raw materials in parts by weight: 70-80 parts of vegetable oil, 20-30 parts of thickener, and 0.1-1 part of additive; wherein the thickener is made from biomass waste, cellulose is first extracted from the biomass waste, and the extracted cellulose is then modified by isocyanate, and the modified fiber finally obtained is the thickener.

[0016] Biomass waste, such as agricultural and forestry waste and food processing waste, usually contains a large amount of cellulose. Cellulose, as a high-quality bio-based raw material, has good physical and chemical properties. Extracting cellulose from these biomass wastes can achieve resource recycling and reduce the load on the environment. However, cellulose is a polyhydroxy compound formed by glucose units connected by glycosidic bonds. The polyhydroxy characteristics in the structure give it a strong polarity, which leads to poor compatibility between cellulose and non-polar vegetable oils. It is difficult to obtain a stable grease gel by directly dispersing cellulose in vegetable oil as a thickener. The present invention is to modify the cellulose extracted from biomass waste by isocyanate, and the hydroxyl groups on the cellulose surface can react with the isocyanate groups to generate carbamates, thereby introducing hydrophobic organic components on the cellulose surface, enhancing the interaction between cellulose and base oil molecules, and achieving a thickening effect, so that the grease can effectively prevent the loss of vegetable oil during operation, thereby having better lubrication performance.

[0017] The additives in the present invention are used to give the grease special properties, such as corrosion resistance, high temperature resistance, extreme pressure performance, etc. The vegetable oil, thickener and additives together constitute the grease. The vegetable oil mainly plays a lubricating role. During operation, the vegetable oil (base oil) will precipitate from the grease to form an oil film on the friction surface, thereby reducing friction and wear. The thickener mainly thickens the vegetable oil (base oil) to form a semi-solid grease.

[0018] 2. The fully bio-based grease provided by the present invention not only reduces the dependence on limited petrochemical resources, but also promotes the resource utilization of agricultural waste, which is in line with the concept of environmental protection and sustainable development. Compared with traditional petroleum-based grease, fully bio-based grease can be decomposed more quickly by microorganisms in the natural environment, reducing long-term pollution to the environment. At the same time, it has the advantages of being renewable, degradable, low-carbon emission, environmentally friendly, and having a wide range of raw material sources.

[0019] In addition to the above-described purposes, features and advantages, the present invention has other purposes, features and advantages. The present invention will be further described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The drawings constituting a part of this application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings: Figure 1 IR images of cellulose extracted from corn stalks before and after isocyanate modification in Example 1; Figure 2 is a scanning electron microscope image of cellulose extracted from corn stalks in Example 1; Figure 3 This is a scanning electron micrograph of cellulose extracted from corn stalks in Example 1 after being modified with isocyanate. DETAILED DESCRIPTION

[0021] The embodiments of the present invention are described in detail below with reference to the accompanying drawings, but the present invention can be implemented in many different ways as defined and covered by the claims.

[0022] The experimental methods in the following examples are conventional methods unless otherwise specified. The raw materials involved in the following examples are common commercial products and can be purchased from the market unless otherwise specified; the detection methods are conventional detection methods unless otherwise specified.

[0023] Example 1 A method for preparing a fully bio-based grease comprises the following steps: S1. Rinse the corn stalks thoroughly with water to remove impurities and residues on the surface, drain and dry at 120 °C for 24 h. After drying, crush the corn stalks with a crusher and sieve them with a 200-mesh screen. Take 10 g of the above corn stalk powder and add it to a mixture of 60 mL toluene and 30 mL ethanol, stir at 100 °C for 6 h, cool to room temperature, filter and wash with ethanol 3 to 5 times, and then dry at 60 °C.

[0024] S2. Add the pretreated product in S1 into 150 mL of 0.1 mol / L HCl solution, stir at 85 °C for 2 h, cool to room temperature, filter and wash with deionized water until neutral, and then dry at 60 °C.

[0025] S3. Add the pretreated material in S2 into a mixture consisting of 100 mL of 6% NaOH solution and 100 mL of 0.7% H2O2 solution, stir at 80 °C for 2 h, cool to room temperature, filter and wash with deionized water until neutral, then put it into a freeze dryer to dry and obtain cellulose.

[0026] S4, add 10 g of cellulose extracted from S3, 5 g of diphenylmethane diisocyanate and 0.5 g of triethylamine to 150 mL of toluene solution, stir and react at room temperature for 24 h under nitrogen atmosphere, filter and wash with toluene 3 to 5 times after the reaction, then dry at 60 ° C for 24 h to obtain isocyanate cellulose, that is, the thickener.

[0027] S5, add 20 parts of S4 to 80 parts of soybean oil under stirring at 80 °C to obtain isocyanate cellulose and 0.5 parts of tocopherol. Then heat to 150 °C, high temperature puffing for 30 min, cool to room temperature, grind 2 to 3 times using a three-roll mill to obtain a fully bio-based grease.

[0028] Example 2 A method for preparing a fully bio-based grease comprises the following steps: S1. Rinse the bagasse thoroughly with water to remove impurities and residues on the surface, drain and dry at 120 °C for 24 h. After drying, crush the bagasse with a crusher and sieve it with a 200-mesh screen. Take 10 g of the above bagasse powder and add it to a mixture of 60 mL toluene and 30 mL ethanol, stir at 80 °C for 8 h, cool to room temperature, filter and wash with ethanol 3 to 5 times, and then dry at 60 °C.

[0029] S2. Add the pretreated product in S1 into 150 mL of 0.15 mol / L HCl solution, stir at 60 °C for 3 h, cool to room temperature, filter and wash with deionized water until neutral, and then dry at 80 °C.

[0030] S3. Add the pretreated material in S2 into a mixture consisting of 100 mL of 5% NaOH solution and 100 mL of 0.5% H2O2 solution, stir at 75 °C for 2.5 h, cool to room temperature, filter and wash with deionized water until neutral, then put it into a freeze dryer to dry and obtain cellulose.

[0031] S4, add 10 g of cellulose extracted from S3, 5 g of toluene diisocyanate and 0.5 g of triethylamine to 150 mL of toluene solution, stir and react at room temperature for 30 h under nitrogen atmosphere, filter and wash with toluene 3 to 5 times after the reaction, then dry at 60°C for 24 h to obtain isocyanate cellulose, that is, the thickener.

[0032] S5, add 20 parts of S4 to 80 parts of castor oil under stirring at 60°C to obtain isocyanate cellulose and 0.5 parts of tocopherol. Then heat to 130°C, expand at high temperature for 20 minutes, cool to room temperature, and grind 2 to 3 times using a three-roll mill to obtain a fully bio-based grease.

[0033] Example 3 A method for preparing a fully bio-based grease comprises the following steps: S1. Rinse the coconut shell thoroughly with water to remove impurities and residues on the surface, drain and dry at 120 °C for 24 hours. After drying, crush the coconut shell with a grinder and sieve it with a 200-mesh screen. Take 10 g of the above coconut shell powder and add it to a mixture of 60 mL toluene and 30 mL ethanol, stir at 120 °C for 4 hours, cool to room temperature, filter and wash with ethanol 3 to 5 times, and then dry at 80 °C.

[0034] S2. Add the pretreated product in S1 into 150 mL of 0.2 mol / L HCl solution, stir at 90°C for 1 h, cool to room temperature, filter and wash with deionized water until neutral, and then dry at 80°C.

[0035] S3. Add the pretreated material in S2 into a mixture of 100 mL of 8% NaOH solution and 100 mL of 0.8% H2O2 solution, stir at 75°C for 2.5 h, cool to room temperature, filter and wash with deionized water until neutral, then put it into a freeze dryer to dry and obtain cellulose.

[0036] S4, add 10 g of cellulose extracted from S3, 5 g of hexamethylene diisocyanate and 0.5 g of triethylamine to 150 mL of toluene solution, stir and react at room temperature for 48 h under nitrogen atmosphere, filter and wash with toluene 3 to 5 times after the reaction, then dry at 80°C for 24 h to obtain isocyanate cellulose, that is, the thickener.

[0037] S5, add 20 parts of S4 to 80 parts of rapeseed oil under stirring at 75°C to obtain isocyanate cellulose and 0.5 parts of tocopherol. Then heat to 120°C, expand at high temperature for 30 minutes, cool to room temperature, and grind 2 to 3 times using a three-roll mill to obtain a fully bio-based grease.

[0038] Comparative Example 1 (unmodified) Under stirring conditions at 80 °C, 20 parts of corn stalk powder and 0.5 parts of tocopherol were added to 80 parts of soybean oil as thickener and antioxidant additive, respectively. Then the temperature was raised to 150 °C, high-temperature puffing was performed for 30 min, and after cooling to room temperature, a three-roll mill was used to grind 2 to 3 times to obtain a fully bio-based grease.

[0039] Comparative Example 2 (too little isocyanate used during modification) The difference between Comparative Example 2 and Example 1 is that in step S4, the amount of diphenylmethane diisocyanate added is 4 g, and the other steps are the same as Example 1.

[0040] Comparative Example 3 (no triethylamine added during the modification process) The difference between Comparative Example 2 and Example 1 is that in step S4, no triethylamine is added, i.e., the amount used is 0, and the other steps are the same as in Example 1.

[0041] Comparative Example 4 (too much triethylamine was used during the modification process) The difference between Comparative Example 2 and Example 1 is that in step S4, the amount of triethylamine added is 1.2 g, and the other steps are the same as in Example 1.

[0042] Figure 1 The infrared images of cellulose extracted from corn stalks in Example 1 before and after isocyanate modification. Figure 1 It can be seen that the modified cellulose has a peak at 2280 cm -1 and 1540 cm -1 New characteristic peaks appeared nearby, corresponding to the unreacted isocyanate groups on the difunctional MDI and the NH on the newly generated carbamate, indicating that the cellulose had been successfully grafted with isocyanate. Figure 2 is a scanning electron microscope image of cellulose extracted from corn stalks in Example 1. Figure 2 It can be seen that the extracted cellulose is fibrous and has a smooth surface. Figure 3 This is a scanning electron micrograph of cellulose extracted from corn stalks after isocyanate modification in Example 1. Figure 3 It can be seen intuitively that after the cellulose was modified, the fiber surface was obviously covered with a layer of isocyanate, which once again indicated that the grafting was successful.

[0043] The tribological properties of Example 1 and Comparative Examples 1-4 were tested using a four-ball friction tester with a load of 40 kgf, a rotation speed of 1200 r / min, and a running time of 60 min. The wear spot diameter of the steel ball was observed using an optical microscope, and the relevant data are detailed in Table 1.

[0044] Table 1: , It can be seen from the test results in Table 1 that compared with the grease made by directly using corn stalk powder as a thickener in Comparative Example 1, the all-biobased grease in Example 1 has significantly reduced friction coefficient, friction force and wear spot diameter, showing excellent tribological properties. This is because compared with the grease made directly from biomass waste, the present invention is modified by isocyanate modification of cellulose extracted from biomass waste, and the hydroxyl groups on the cellulose surface can react with the isocyanate groups to generate carbamate, thereby introducing hydrophobic organic components on the cellulose surface, enhancing the interaction between cellulose and base oil molecules, and achieving a thickening effect, so that the grease can effectively prevent the loss of vegetable oil during operation, thereby having better lubrication performance. In Comparative Example 2, the amount of isocyanate added during the process is reduced, resulting in a decrease in the degree of grafting on the cellulose surface, so that the tribological properties are also reduced. The amount of catalyst triethylamine added also has a significant effect on the tribological properties of the grease, such as Comparative Examples 3 and 4. When no triethylamine was added in Comparative Example 3, the reaction between cellulose and isocyanate was difficult to proceed, so the base oil in the prepared grease had poor binding ability with cellulose, and the tribological performance was also worse than that of Example 1; while in Comparative Example 4, excessive triethylamine was added, which accelerated the reaction between cellulose and isocyanate, the degree of cellulose grafting was uneven, and the stability of the grease was reduced, which also led to a decrease in tribological performance. The all-biobased greases prepared in Examples 2 and 3 had similar properties to those prepared in Example 1, and will not be described in detail here.

[0045] In summary, the present invention provides a kind of all-bio-based grease, which is modified by isocyanate modification of cellulose extracted from biomass waste, and the hydroxyl groups on the surface of cellulose can react with isocyanate groups to generate carbamates by nucleophilic addition reaction, thereby introducing hydrophobic organic components on the surface of cellulose, enhancing the interaction between cellulose and base oil molecules, and achieving a thickening effect, so that the grease can effectively prevent the loss of vegetable oil during operation, thereby having better lubrication performance. At the same time, the role of the additives in the present invention is to give the grease special properties, such as corrosion resistance, high temperature resistance, extreme pressure performance, etc. Vegetable oil, thickener and additives together constitute the grease, and the vegetable oil mainly plays a lubricating role. During operation, the vegetable oil (base oil) will precipitate from the grease and form an oil film on the friction surface, thereby playing a role in reducing friction and wear, and the thickener mainly thickens the vegetable oil (base oil) to form a semi-solid grease.

[0046] The fully bio-based grease provided by the present invention not only reduces the dependence on limited petrochemical resources, but also promotes the resource utilization of agricultural waste, which is in line with the concept of environmental protection and sustainable development. Compared with traditional petroleum-based grease, the fully bio-based grease can be decomposed more quickly by microorganisms in the natural environment, reducing long-term pollution to the environment. At the same time, it has the advantages of being renewable, degradable, low-carbon emission, environmentally friendly, and having a wide range of raw material sources.

[0047] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A fully bio-based grease, characterized in that: The all-biobased grease comprises the following raw materials in parts by weight: 70-80 parts of vegetable oil, 20-30 parts of thickener, and 0.1-1 part of additive; The thickener is made from biomass waste as raw material. The cellulose in the biomass waste is firstly extracted, and then the extracted cellulose is modified by isocyanate. The modified fiber finally obtained is the thickener.

2. A fully bio-based grease according to claim 1, characterized in that: The vegetable oil includes any one of soybean oil, castor oil, palm oil, coconut oil or rapeseed oil, or a combination of at least two of them.

3. A fully bio-based grease according to claim 1, characterized in that: The additives include any one of an antioxidant, an extreme pressure agent and a rust remover, or a combination of at least two of them.

4. A fully bio-based grease according to claim 3, characterized in that: The antioxidant includes any one or a combination of at least two of octylbutyl diphenylamine, diisooctyl diphenylamine, thiophenol antioxidants, p-methylphenol or tocopherol; The extreme pressure agent includes any one or a combination of at least two of calcium stearate, molybdenum di-n-butyl dithiocarbamate, zinc dialkylthiophosphate, borate or nano-grade zinc oxide; The rust remover comprises any one of medium-base calcium sulfonate, barium sulfonate or sodium sebacate, or a combination of at least two of them.

5. A fully bio-based grease according to any one of claims 1 to 4, characterized in that: The thickener comprises the following preparation steps: S1. First pretreatment: Take an appropriate amount of biomass waste and add it to a mixed solution of toluene and ethanol, stir it at 80-120 °C for 4-8 h, cool it to room temperature, filter it and wash it with ethanol, and then dry it at 60-80 °C; S2. Second pretreatment: add the pretreated material in S1 to a 0.1-0.2 mol / L HCl solution, stir at 60-90°C for 1-3 h, cool to room temperature, filter and wash with deionized water until neutral, and then dry at 60-80°C; S3. Extraction of cellulose: The pretreated material in S2 was added to a mixture of 5-8% NaOH solution and 0.5-0.8% H2O2 solution by mass, stirred at 60-80°C for 2-3 h, cooled to room temperature, filtered, washed with deionized water until neutral, and then dried in a freeze dryer; S4. Modification of cellulose: Add the above cellulose, isocyanate and triethylamine to a toluene solution respectively, and react with stirring at room temperature for 24-48 h under a nitrogen atmosphere. After the reaction is completed, filter and wash with toluene for 3-5 times, and then dry at 60-80°C for 24 h to obtain a thickener.

6. A fully bio-based grease according to claim 5, characterized in that: In step S1, the biomass waste includes any one or a combination of at least two of cotton stalks, corn stalks, wheat stalks, bean stalks, rice husks, peanut shells, coconut shells, sunflower husks, rice straw and sugarcane bagasse; In step S4, the isocyanate includes any one or a combination of at least two of diphenylmethane diisocyanate, toluene diisocyanate, dicyclohexylmethane diisocyanate, hexamethylene diisocyanate and isophorone diisocyanate.

7. A fully bio-based grease according to claim 5, characterized in that: In step S1, the ratio of toluene, ethanol and biomass waste is 50-80 mL: 20-40 mL: 5-15 g.

8. The all-biobased grease according to claim 5, characterized in that: In step S2, the ratio of HCl solution to biomass waste is 100-200 mL: 5-15 g; in step S3, the ratio of NaOH solution, H2O2 solution and biomass waste is 100 mL: 100 mL: 5-15 g.

9. The all-biobased grease according to claim 5, characterized in that: In step S4, the ratio of toluene, cellulose, isocyanate and triethylamine is 100-200 mL: 10 g: 5-10 g: 0.5-1 g.

10. A method for preparing a fully bio-based grease according to any one of claims 1 to 9, characterized in that: The method comprises the following steps: stirring a thickener and vegetable oil at 60-80°C to obtain a uniform mixture, then heating to 120-150°C for high-temperature expansion for 8-30 minutes, and finally adding additives and grinding with a three-roll grinder to obtain the fully bio-based grease.

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