Preparation method of nano organic carboxylic acid soap with super large specific surface area and product thereof

Abstract

This invention relates to the field of organic carboxylic acid soap technology, and specifically provides a method for preparing nano-organic carboxylic acid soap with an ultra-large specific surface area and the resulting product. The invention uses water as a carrier, alkylphenol polyoxyethylene ether as a template agent, a freshly prepared suspension dispersion of amorphous organic carboxylic acid soap containing the template agent as a precursor, and an excess of water-soluble alkaline solution as a cation source. An open-boiling reflux process is employed to synthesize an organic carboxylic acid soap with a nanofiber structure in one step. Subsequently, the product is obtained by centrifugal dehydration, washing to remove impurities, and vacuum spray drying to produce a dry soap powder. The prepared soap powder has an ultra-large specific surface area of ​​220–280 m² / g. 2 / g; nanofiber structure, approximately 5–20 nm in diameter and 20–200 μm in length. The produced soap powder can be directly thickened with base oil at room temperature to create soap-based grease. The production process requires no high-temperature refining step, making it safe, energy-saving, emission-reducing, and environmentally friendly. The resulting soap-based grease is white, transparent, and odorless.

Description

Technical Field

[0001] This invention relates to the field of organic carboxylic acid soap technology, and in particular provides a method for preparing nano-organic carboxylic acid soap with an ultra-large specific surface area and the product thereof. Background Technology

[0002] Grease is a type of semi-solid lubricant made by thickening base oil with a thickener. Grease has become one of the essential raw materials in modern basic industries and modern technological products.

[0003] According to statistics, the annual output of lubricating greases (soap-based greases) using organic carboxylic acid soaps as thickeners is currently about 900,000 tons, accounting for about 75% of the total output. With the continuous changes in the application scenarios of lubricating greases, higher requirements are being placed on the preparation of lubricating greases (soap-based greases).

[0004] Based on recently published literature, it can be seen that most existing soap-based grease production processes require high-temperature refining / expansion steps. These processes have the following shortcomings: (1) Due to the long-term high-temperature refining process, the energy consumption is huge: based on a production volume of 1 ton, it usually takes 8 to 10 hours to heat up from room temperature to 180 to 220°C, and the larger the production volume, the longer the heating time; in addition, the high-temperature stage also requires 30 to 60 minutes of heat preservation. The electricity consumption is about 600 kWh / ton (see Chinese patents 96120874.0, 201410806828.6, 201510993426.6, 202411174967.1).

[0005] (2) Base oil and thickener are prone to performance degradation and oxidation when exposed to high temperature production environment for a long time, resulting in grease oxidation, darkening and yellowing of color, producing obvious odor, and significantly increasing toxic VOCs (see Chinese Patent 201911300036.0).

[0006] (3) Some additives required in the production formula (functional materials with relatively active reactivity) are easily oxidized and deteriorated at high temperatures. They need to be added at a certain time after being cooled to a certain temperature (such as 90°C and below) in the production process, which increases the workload. In addition, the production equipment used in the early stage needs to be cleaned in time to avoid the residual additives from oxidizing and deteriorating due to the high temperature refining process when the production equipment is reused, producing an odor and other side effects (see Chinese Patents 202311680251.4, 202311384813.0, 202411011661.4).

[0007] (4) The production process of pre-made soap is subject to solvent pollution; the risk is even greater when it is mass-produced. In addition to more solvent emissions polluting the environment, there is also the safety risk of the solvent being flammable and explosive (see Chinese patents 200510004958.9, 201911300036.0, 202010795350.7, 202110007890.9). Summary of the Invention

[0008] To address the shortcomings of the prior art, this invention provides a method for preparing nano-organic carboxylic acid soap with an ultra-large specific surface area and its product (soap-based grease).

[0009] This invention first simplifies the production process of soap-based greases, eliminating the high-temperature refining / expansion process and the use of pre-made soap. Instead, it first invents a method for preparing nano-carboxylic acid soaps with ultra-large specific surface area that does not use organic solvents in the production process and can be mass-produced. Then, the prepared soap powder is used to directly thicken the base oil at room temperature to obtain a high-performance soap-based lubricating grease.

[0010] To achieve the above-mentioned technical objectives, the present invention provides a method for preparing a nano-organic carboxylic acid soap with an ultra-large specific surface area, comprising the following steps: Step 1, Material Preparation: The materials include organic carboxylic acid, lithium hydroxide monohydrate, water-soluble alkali, template agent, and water; wherein the molar ratio of organic carboxylic acid, lithium hydroxide monohydrate, and water-soluble alkali is 1:1:(0.1~0.2). Step 2: Prepare a water-soluble alkali aqueous solution: Mix water-soluble alkali with water at a weight ratio of 1:(2-5) and stir at room temperature for 10-20 minutes until the water-soluble alkali is completely dissolved to obtain a water-soluble alkali aqueous solution for later use. Step 3: Prepare lithium hydroxide aqueous solution: Add lithium hydroxide monohydrate and water in a weight ratio of 1:(3-5) into the material heating tank at one time, heat to 85-100℃, stir for 10-20 minutes until the lithium hydroxide monohydrate is completely dissolved, and prepare lithium hydroxide aqueous solution for later use. Step 4: Preparation of suspension dispersion precursor: Add organic carboxylic acid, template agent and water in a weight ratio of 1:(0.1~0.2):(2~5) into an open reactor at once, heat to 80~90℃, stir vigorously, and then slowly add the lithium hydroxide aqueous solution prepared in step 3. After completion, continue to keep the reaction at the temperature for 60~90 minutes to obtain a suspension dispersion precursor of amorphous organic carboxylic acid soap containing template agent, for later use; Step 5: Preparation of nano-organic carboxylic acid soap: The water-soluble alkaline solution obtained in step 2 is slowly added to the open reactor of the suspension dispersion precursor obtained in step 4. After completion, stirring is continued for 30 minutes. Then, the temperature is raised to 95-105°C and then kept at the open for boiling and reflux reaction for 120-150 minutes to obtain organic carboxylic acid soap wet cake. Step 6, centrifugal dehydration: Discharge the material and centrifuge it in a bag centrifuge for 30-60 minutes until completely dehydrated; Step 7, Washing to remove impurities: Wash with filtered pure water to remove impurities, and then centrifuge again to completely dehydrate; Step 8, Reduced pressure spray drying: Mix the cleaned organic carboxylic acid soap wet cake with water in a 1:1 ratio to form a slurry, and then perform reduced pressure spray drying at a temperature of 100-120℃ and a pressure of -0.01MPa to obtain dry soap powder.

[0011] The organic carboxylic acid can be one or more of the following: lauric acid, palmitic acid, oleic acid, stearic acid, 12-hydroxystearic acid (monocarboxylic acids); sebacic acid, azelaic acid, dodecanoic acid (dicarboxylic acids); and triazine polycarboxylic acids (tricarboxylic acids), preferably 12-hydroxystearic acid.

[0012] The template agent used is alkylphenol polyoxyethylene ether (APEO), an important polyoxyethylene nonionic surfactant characterized by stability, acid and alkali resistance, and low cost. Based on the alkyl structure, it is further classified into nonylphenol polyoxyethylene ether (NPEO), octylphenol polyoxyethylene ether (OPEO), and dodecyl polyoxyethylene ether (DPEO). The number of polyoxyethylene ethers in the molecular structure varies from 1 to 40; however, the number of polyoxyethylene ethers directly affects the water and oil solubility properties of APEO. Here, the preferred number of polyoxyethylene ethers is 4 to 8.

[0013] The water-soluble alkali is one or more of lithium hydroxide monohydrate, sodium hydroxide, potassium hydroxide, and barium hydroxide.

[0014] In the process for preparing nano-organic carboxylic acid soaps according to this invention, steps 4 and 5 are key steps. Using the above preparation method, pure nano-organic carboxylic acid soaps with ultra-large specific surface areas can be directly obtained in one step: all possessing ultra-large specific surface areas of 220–280 m². 2 / g; nanofiber structure, with a diameter of about 5-20 nm and a length of about 20-200 μm. Based on the nano-organic carboxylic acid soap produced in this invention, soap-based ester products can be further produced using a simple room temperature thickening method.

[0015] A certain proportion of additives and base oil, together with the dry soap powder obtained in step 8, can be added to the mixing tank used for the production of soap-based grease. The mixture is stirred evenly at room temperature and then ground three times on a three-roll mill to obtain soap-based lubricating grease.

[0016] The base oil may be one or a combination of polyalphaolefin (PAO), mineral oil, alkylnaphthalene, alkylbenzene, synthetic ester, polyether, polysiloxane, perfluoropropyl polysiloxane, and perfluoropolyether, with a viscosity range (V40℃) of 20 to 2000 cSt.

[0017] The additives may be one or a combination of antioxidants, rust inhibitors, anti-wear extreme pressure agents, pigments, thickeners, etc., and the amount added is not limited, but the amount of a single agent is usually 0.1% to 10.0%. The technical solution of this invention has the following advantages: ① The reaction system uses only water as a solvent carrier, which is green, environmentally friendly, and pollution-free; ② An open-type reaction vessel device is used, which is not limited by scale-up; ③ The raw materials are all mass-produced industrial products, which are readily available; ④ The soap powder produced has an ultra-large specific surface area and a nano-long fiber structure, which can directly thicken the base oil at room temperature to produce a white, transparent, and odorless soap-based grease; ⑤ The grease-making process directly eliminates the high-temperature refining step, which meets the current technical requirements of energy conservation, emission reduction, and green environmental protection. Attached Figure Description

[0018] Figures 1-4 This is a microscopic photograph of the product of Example 1 in this invention.

[0019] Figures 5-10 This is a microscopic photograph of the product of Example 2 in this invention.

[0020] Figures 10-12 This is a microscopic photograph of the product of Example 3 in this invention. Detailed Implementation

[0021] The following detailed description of the preparation method of a nano-organic carboxylic acid soap with an ultra-large specific surface area according to the present invention is provided in conjunction with embodiments.

[0022] To obtain the technical solution of this invention, the inventors conducted a large number of basic experiments using orthogonal experimental methods and mutual comparison methods, especially in terms of material composition, material formulation, proportion and production process. Finally, the material formulation and process parameters were determined. Among them, the material formulations that have been verified and qualified are shown in Table 1, and the process steps and parameters that have been verified and qualified are shown in Table 2.

[0023] Table 1

[0024] Table 2

[0025] Based on the aforementioned scientific verification, a method for preparing a nano-organic carboxylic acid soap with an ultra-large specific surface area according to the present invention is derived, comprising the following steps: 1) Material preparation: The materials include organic carboxylic acid, lithium hydroxide monohydrate, water-soluble alkali, template agent and water; wherein the molar ratio of organic carboxylic acid, lithium hydroxide monohydrate and water-soluble alkali is 1:1:(0.1~0.2); 2) Prepare a water-soluble alkali aqueous solution: Mix water-soluble alkali with water at a weight ratio of 1:(2~5) directly, stir at room temperature for 10~20 minutes until the water-soluble alkali is completely dissolved, and prepare a water-soluble alkali aqueous solution for later use; 3) Preparation of lithium hydroxide aqueous solution: Add lithium hydroxide monohydrate and water in a weight ratio of 1:(3~5) into the material heating tank at one time, heat to 85~100℃, stir for 10~20 minutes until the lithium hydroxide monohydrate is completely dissolved, and prepare lithium hydroxide aqueous solution for later use. 4) Preparation of suspension dispersion precursor: Organic carboxylic acid, template agent and water in a weight ratio of 1:(0.1~0.2):(2~5) are added into an open reactor at once, heated to 80~90℃, stirred vigorously, and then the lithium hydroxide aqueous solution prepared in step (3) is slowly added. After completion, the reaction is continued for 60~90 minutes to obtain a suspension dispersion precursor of amorphous organic carboxylic acid soap containing template agent, for later use; 5) Preparation of nano-organic carboxylic acid soap: The water-soluble alkaline solution obtained in step (2) is slowly added to the open reactor of the suspension dispersion precursor obtained in step (4). After completion, stirring is continued for 30 minutes. Then, the temperature is raised to 95-105°C and then kept warm in an open boiling reflux reaction for 120-150 minutes to obtain organic carboxylic acid soap wet cake. 6) Centrifugal dehydration: Discharge the material and centrifuge it in a bag-type high-speed centrifuge for 30-60 minutes until it is completely dehydrated; 7) Washing to remove impurities: Wash with filtered pure water to remove impurities, and then centrifuge again to completely dehydrate; 8) Reduced pressure spray drying: Mix the cleaned organic carboxylic acid soap wet cake with water in a 1:1 ratio to form a water slurry, and then perform reduced pressure spray drying at a temperature of 100-120℃ and a pressure of -0.01MPa to obtain dry soap powder. In the following examples, Example 1 is the best example (including specific experimental parameters), and Examples 2 and 3 are comparative examples under different conditions. Specifically, Example 2 verified the effects of template agent and excess alkaline solution on the synthesis of nano-organic carboxylic acid soap. The results showed that both are indispensable, which is also the key to the success of this invention. Example 3 verified the attempt to use a combination of commercially available lithium soap powder (lithium 12-hydroxystearate) + template agent + water to replace the freshly prepared amorphous 12-hydroxystearate suspension containing the template agent. However, the experimental results showed that commercially available lithium soap powder could not replace the freshly prepared precursor. Example

[0026] Example 1 includes four different sub-examples (1A~1D, 4 examples). This example is the best example and also the mass production example. An open reactor apparatus is used, with a reactor volume of 1500L. A list of material formulations for the specific sub-examples is shown in Table 3 (unit of measurement is kg, including experimental test results). In this example, the corresponding materials are slightly different, specifically the template agent APEO and the water-soluble alkaline material have been adjusted; the production process is carried out according to the process flow in Table 2, and the specific process parameters for the four sub-examples are shown in Table 4.

[0027] Table 3

[0028] illustrate: *1. The smaller the cone penetration value, the thicker the grease, indicating that the soap thickener has a stronger thickening ability on the base oil and better performance.

[0029] *2. The lower the oil separation rate of the stencil, the better the colloidal stability of the grease, indicating a better bonding force between the soap thickener and the base oil.

[0030] *3. The smaller the four-ball wear scar value, the better the anti-wear performance and lubrication performance of the grease. The production process steps and parameters corresponding to Example 1 (1A~1D, 4 units) are shown in Table 4 (mass production). Table 4

[0031] The characteristics of the finished product corresponding to Example 1 (1A~1D, 4 pieces): 1A: The soap powder produced has a nanofiber structure with a diameter of approximately 5–20 nm and a length of approximately 20–200 μm; its specific surface area is 276 m². 2 / g; It can thicken base oil PAO-10 very well.

[0032] 1B: The soap powder produced has a nanofiber structure with a diameter of approximately 5–20 nm and a length of approximately 20–200 μm; its specific surface area is 267 m².2 / g; It can thicken base oil PAO-10 very well.

[0033] 1C: The soap powder produced has a nanofiber structure with a diameter of approximately 5–20 nm and a length of approximately 20–200 μm; its specific surface area is 235 m². 2 / g; It can thicken base oil PAO-10 very well.

[0034] 1D: The soap powder produced has a nanofiber structure with a diameter of approximately 5–20 nm and a length of approximately 20–200 μm; its specific surface area is 258 m². 2 / g; It can thicken base oil PAO-10 very well.

[0035] See the corresponding microscopic photographs Figures 1-4 Using Example 1, the inventors have successfully achieved stable batch production of organic carboxylic acid soaps in a 1500L open reactor. This soap has been applied to the company's independently developed soap-based grease products. After being put into the market, the feedback has been positive. The resulting soap-based grease products are white and translucent, odorless, and possess excellent lubricating properties. Example

[0036] Example 2 includes eight sub-examples (2A~2H, 8 in total), further divided into two groups. Group 1 (2A~2E) investigated the effects of template agents and excess alkali on the synthesis of nano-organic carboxylic acid soaps from freshly prepared amorphous organic carboxylic acid soap suspensions. Group 2 (2F, 2G, 2H) investigated the lipid-lowering effect of conventional methods. This example was conducted on a 2L open-top reactor. A list of specific material formulations is shown in Table 5 (unit of measurement is g, including experimental test results). Experiments were conducted to investigate the presence or absence of the template agent APEO, the presence and amount of water-soluble alkali, and different water-soluble alkalis. The production process followed the process flow in Table 2. The specific process parameters for the eight sub-examples are shown in Table 6.

[0037] Table 5

[0038] Table 6

[0039] The verification results of different schemes in the aforementioned Example 2 are as follows: 2A: The combination of precursor, template agent, and excess alkali is necessary for effectiveness. The template agent forms the spatial structure, while the excess alkali leads to a dissolution-precipitation process, ultimately resulting in a specific microstructure and specific surface area.

[0040] 2B: It has a precursor, no template agent, excess alkali, a dissolution-precipitation process, no morphological structure, but cannot form a nanofiber structure.

[0041] 2C: It has a precursor, a template agent, no excess alkali, no dissolution-precipitation process, no morphological structure, and cannot form a nanofiber structure.

[0042] 2D: It contains precursors, template agents, and a small amount of excess alkali. The dissolution-precipitation process is not obvious. It has amorphous and short fibers and cannot form a nanofiber structure.

[0043] 2E: It contains precursors, template agents, and excessive alkali. The dissolution-precipitation process is quite obvious. It has amorphous and coarse fibers and cannot form a nanofiber structure.

[0044] 2F: Cannot form lipids at room temperature.

[0045] 2G: It can only be thickened into grease under a high-temperature refining process of 220℃. The product turns yellow and has a distinct oxidized odor, resulting in unsatisfactory results.

[0046] 2H: It can only be thickened into fat under a high-temperature refining process of 220℃, but the product turns yellow and has a distinct oxidized odor, resulting in an unsatisfactory outcome.

[0047] Conclusion: Example 2 verified the effects of template agent and excess alkaline solution on the synthesis of nano-organic carboxylic acid soap. The results showed that both are indispensable and are the key to the success of this invention.

[0048] See the corresponding microscopic photographs Figures 5-9 . Example

[0049] Example 3 includes ten different sub-examples (3A~3J, 10 in total), which are further divided into three groups. Group 1 (3A~3E) explored the phase inversion effect of template agent and excess alkali on commercially available lithium soap powder; Group 2 (3F, 3G) explored the fat-reducing effect of commercially available lithium soap powder; and Group 3 (3H, 3I, 3J) explored the phase inversion effect of different water-soluble alkalis on commercially available lithium soap powder. All experiments in Example 3 were conducted on a 2L open-top reactor. A list of material formulations for the specific sub-examples is shown in Table 7 (unit of measurement is g, including experimental results). The materials differed, specifically regarding the presence or absence of template agent APEO, the presence and amount of water-soluble alkali, and the use of different water-soluble alkalis. The production process followed the process flow and parameters of sub-example 2A in Example 2.

[0050] Table 7

[0051] In this study, commercially available lithium soap powder was used as the initial precursor material. Example 3 verified an experimental scheme that attempted to replace the freshly prepared amorphous 12-hydroxystearate suspension dispersion containing the template agent with a composition of commercially available lithium soap powder (lithium 12-hydroxystearate) + template agent + water. The study examined the microstructure, specific surface area, and lipid formation of the soap powder after phase inversion. The results showed that commercially available lithium soap powder cannot replace the freshly prepared precursor.

[0052] See the corresponding microscopic photographs Figures 10-12 . The above description illustrates and describes the basic principles, main features, and advantages of the present invention. It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments mentioned herein should be considered exemplary and non-limiting. Those skilled in the art should consider the specification as a whole, and the technical solutions in the various embodiments can be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A process for the preparation of nano-organic carboxylic acid soaps of ultra-high specific surface area, characterized in that, Includes the following steps: 1) Material preparation: The materials include organic carboxylic acid, lithium hydroxide monohydrate, water-soluble alkali, template agent and water; wherein the molar ratio of organic carboxylic acid, lithium hydroxide monohydrate and water-soluble alkali is 1:1:(0.1~0.2); 2) Prepare a water-soluble alkali aqueous solution: Mix water-soluble alkali with water at a weight ratio of 1:(2~5) directly, stir at room temperature for 10~20 minutes until the water-soluble alkali is completely dissolved, and prepare a water-soluble alkali aqueous solution for later use; 3) Preparation of lithium hydroxide aqueous solution: Add lithium hydroxide monohydrate and water in a weight ratio of 1:(3~5) into the material heating tank at one time, heat to 85~100℃, stir for 10~20 minutes until the lithium hydroxide monohydrate is completely dissolved, and prepare lithium hydroxide aqueous solution for later use. 4) Preparation of suspension dispersion precursor: Organic carboxylic acid, template agent and water in a weight ratio of 1:(0.1~0.2):(2~5) are added into an open reactor at once, heated to 80~90℃, stirred vigorously, and then the lithium hydroxide aqueous solution prepared in step (3) is slowly added. After completion, the reaction is continued for 60~90 minutes to obtain a suspension dispersion precursor of amorphous organic carboxylic acid soap containing template agent, for later use; 5) Preparation of nano-organic carboxylic acid soap: The water-soluble alkaline solution obtained in step (2) is slowly added to the open reactor of the suspension dispersion precursor obtained in step (4). After completion, stirring is continued for 30 minutes. Then, the temperature is raised to 95-105°C and then kept warm in an open boiling reflux reaction for 120-150 minutes to obtain organic carboxylic acid soap wet cake. 6) Centrifugal dehydration: Discharge the material and centrifuge it in a bag-type high-speed centrifuge for 30-60 minutes until it is completely dehydrated; 7) Washing to remove impurities: Wash with filtered pure water to remove impurities, and then centrifuge again to completely dehydrate; 8) Reduced pressure spray drying: Mix the cleaned organic carboxylic acid soap wet cake with water in a 1:1 ratio to form a water slurry, and then perform reduced pressure spray drying at a temperature of 100-120℃ and a pressure of -0.01MPa to obtain dry soap powder.

2. The method of synthesis of claim 1, wherein, The organic carboxylic acid is one or more of the following: lauric acid, palmitic acid, oleic acid, stearic acid, and 12-hydroxystearic acid (monocarboxylic acids); sebacic acid, azelaic acid, and dodecanoic acid (dicarboxylic acids); and triazine polycarboxylic acids (tricarboxylic acids).

3. The method of synthesis of claim 2, wherein, The organic carboxylic acid is preferably 12-hydroxystearic acid.

4. The method of synthesis of claim 1, wherein, The template agent is alkylphenol polyoxyethylene ether.

5. The method of synthesis of claim 4, wherein, The alkylphenol polyoxyethylene ether is nonylphenol polyoxyethylene ether, octylphenol polyoxyethylene ether, or dodecyl polyoxyethylene ether; wherein the quantity of the polyoxyethylene ether is any value from 1 to 40.

6. The method of synthesis of claim 5, wherein, The preferred quantity of the polyoxyethylene ether is 4 to 8.

7. The method of synthesis of claim 1, wherein, The water-soluble alkali is one or a combination of lithium hydroxide monohydrate, sodium hydroxide, potassium hydroxide, and barium hydroxide.

8. A soap-based grease made using the dry soap powder of claim 1, characterized in that, The prepared dry soap powder is mixed with base oil and additives, stirred evenly at room temperature, and then ground on a three-roll mill.

9. The soap-based grease of claim 8, wherein, The base oil may be one or a combination of polyalphaolefin, mineral oil, alkylnaphthalene, alkylbenzene, synthetic ester, polyether, polysiloxane, perfluoropropyl polysiloxane, and perfluoropolyether, with a viscosity range of 20 to 2000 cSt; the additive may be one or a combination of antioxidant, rust inhibitor, anti-wear extreme pressure agent, pigment, and tackifier, with a single agent dosage of 0.1% to 10.0%.

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