Superfine modified coal series kaolinite-DMSO-CTAC intercalation compound as well as preparation method and application thereof

Abstract

The invention discloses a superfine modified coal series kaolinite-DMSO-CTAC intercalation compound as well as a preparation method and application thereof, and belongs to the technical field of high-resistance lubricating grease. Coal series kaolinite, dimethyl sulfoxide and cetyltrimethylammonium chloride are adopted as raw materials, the novel lubricating grease material is finally prepared by performing ultrasonic crushing on the coal series kaolinite, performing ultrasonic intercalation on superfine coal series kaolinite and performing plasma ball-milling stripping on superfine modified coal series kaolinite, and polytetrafluoroethylene is combined. After the compound is modified, the interlayer spacing is obviously increased, so that more lubricant molecules can enter the interlayer, and the lubricating property is improved; the surface property is improved, the hydrophilicity in the lubricating grease can be weakened, the lipophilicity in the lubricating grease can be enhanced, and the prepared novel lubricating grease material can keep complete and effectively prevent direct contact of friction surfaces under extreme conditions, so that friction, abrasion and damage are reduced, and stable lubricating performance is kept.

Description

Technical Field

[0001] The invention relates to the technical field of high-resistance grease preparation, and in particular to an ultrafine modified coal-based kaolinite-DMSO-CTAC intercalation compound and a preparation method and application thereof. Background Art

[0002] my country has rich coal resources, and coal gangue, as a byproduct mineral of coal mining, is produced in large quantities every year. Coal-series kaolin is a type of kaolinite gangue, which has the characteristics of low mining cost and excellent performance. Its structure is a layered silicate structure with weak interlayer force, so it has good friction reduction, physical and chemical properties and insulation properties. Intercalation-modified kaolin can increase the interlayer spacing and specific surface area, improve its surface properties, and thus significantly improve its lubrication performance.

[0003] With the improvement of my country's industrial capacity, the market has put forward higher requirements for the performance of lubricants. Different from ordinary low-grade lubricants, lubricants with higher anti-wear, high friction reduction, high insulation and other properties are the current development trend, in order to adapt to various extreme conditions such as heavy load, high temperature, high pressure or impact load, and still be able to remain intact and effectively prevent direct contact between friction surfaces, thereby reducing friction, wear and damage, and maintaining stable lubrication performance. Therefore, seeking higher performance and lower cost lubricants is a research hotspot in the current industry. In order to improve the anti-wear and friction reduction properties of grease, as well as its stability under extreme pressure conditions, the research work on applying ultrafine coal-based kaolinite-DMSO-CTAC intercalation compounds to grease has not been reported in the literature in China. Summary of the invention

[0004] The purpose of the present invention is to provide an ultrafine modified coal-based kaolinite-DMSO-CTAC intercalation compound and a preparation method and application thereof to solve the above-mentioned problems. The present invention combines the lubricity of potassium acetate with the layered structure advantages of kaolin, can form a stable lubricating film on the friction surface, reduce friction and wear, improve the load-bearing capacity and extreme pressure resistance of the grease, and help improve the fluidity and pumping performance of the grease, forming an additive with unique lubricating properties, and expanding the application range of the grease material.

[0005] To achieve the above object, the present invention discloses a method for preparing an ultrafine modified coal-based kaolinite-DMSO-CTAC intercalation compound, comprising the following steps:

[0006] S1. Prepare a mixed material: add 10-30 ml of deionized water to 10 g of coal-based kaolin raw material, stir thoroughly, and evenly disperse the coal-based kaolin in the deionized water to prepare a mixed material;

[0007] S2. Ultrasonic crushing of coal-based kaolin: put the mixed material prepared in S1 into an ultrasonic cell disruptor, extend the ultrasonic probe below the liquid surface, 10-15 mm from the bottom of the cup, use an ultrasonic power of 600-1000 W, an ultrasonic time of 1-3 h, and an ultrasonic frequency of 10-30 kHz to complete the ultrasonic crushing of coal-based kaolin;

[0008] S3, preparation of ultrafine coal-based kaolinite / DMSO intercalation complex: dissolving the ultrafine coal-based kaolinite prepared in S2 in deionized water from which CO2 has been removed to prepare a mixed solution;

[0009] S4, adding dimethyl sulfoxide to the mixed solution prepared in S3 to prepare an ultrafine coal-based kaolinite / DMSO suspension, wherein the mass volume ratio of the mixed solution to dimethyl sulfoxide is 1 g: (7-10) ml;

[0010] S5. Place the small beaker containing the ultrafine coal-based kaolinite / DMSO suspension into an ultrasonic cell disruptor to intercalate the ultrafine coal-based kaolinite. Extend the ultrasonic probe below the liquid surface, 10 to 15 mm from the bottom of the cup. The ultrasonic power is 150 w to 250 w, the ultrasonic time is 3 to 5 h, and the ultrasonic frequency is 8 to 12 kHz.

[0011] S6, adding anhydrous ethanol to the suspension prepared in S5 to wash the potassium acetate remaining on the surface of the kaolinite, and obtaining an ultrafine coal-based kaolinite / DMSO intercalation composite after separation and drying;

[0012] S7. Add hexadecyltrimethylammonium chloride to the methanol solution to obtain a CTAC methanol solution, add the ultrafine coal-based kaolinite / DMSO intercalation complex thereto and mix and stir, the concentration of hexadecyltrimethylammonium chloride in the CTAC methanol solution after mixing is 0.5-1 mol / L, and the solid-liquid ratio of the ultrafine coal-based kaolinite / DMSO intercalation complex to the CTAC methanol solution is 1 g:(2-4) ml.

[0013] S8. The slurry prepared in S7 is subjected to plasma ball milling treatment, the ball mill speed is 200-300 r / min, and the ball milling time is 1-3 h. After the treatment, the CTAC remaining on the surface is washed away with a methanol solution, and ultrafine modified coal-based kaolinite-DMSO-CTAC is obtained after separation and drying.

[0014] Preferably, in step S1, the solid-liquid ratio of coal-based kaolin and deionized water is 1 g:(2-3) ml, and in step S2, the ultrasonic power is 600-800 w, the ultrasonic time is 3 h, and the ultrasonic frequency is 20-30 kHz.

[0015] Preferably, in step S4, the mass volume ratio of the mixed solution to dimethyl sulfoxide is 1 g:1 ml, and in step S5, the ultrasonic power is 150w-250w, the ultrasonic time is 3-5h, and the ultrasonic frequency is 8-12kHz.

[0016] Preferably, in step S7, the concentration of hexadecyltrimethylammonium chloride in the CTAC methanol solution after mixing is 0.4 mol / L, and the solid-liquid ratio of the ultrafine coal-based kaolinite / DMSO intercalation complex to the CTAC methanol solution is 1 g:(2-4) ml.

[0017] Preferably, in step S8, the ball mill speed is 200 r / min, and the ball milling time is 1.5 h.

[0018] The present invention also provides an ultrafine modified coal-based kaolinite-DMSO-CTAC intercalation compound, which is prepared by the above-mentioned method for preparing the ultrafine modified coal-based kaolinite-DMSO-CTAC intercalation compound.

[0019] The ultrafine modified coal-based kaolinite-DMSO-CTAC intercalation compound provided by the invention is used as an additive in preparing lubricating grease.

[0020] Preferably, the specific preparation steps of the grease are as follows:

[0021] (1) Add microcrystalline wax as a dispersant to the base oil, heat to 100-110° C., stand for 30 minutes and then stir, add polytetrafluoroethylene powder and petroleum ether and stir, wherein the mass fraction of the base oil is 30-50%, the mass fraction of the microcrystalline wax is 3-5%, the mass fraction of the polytetrafluoroethylene powder is 30-40%, and the mass fraction of the petroleum ether is 1-2%.

[0022] (2) The mixture prepared in (1) is heated in an oil bath in a beaker until the petroleum ether is completely volatilized, and ultrafine modified coal-based kaolinite-DMSO-CTAC and transformer oil are added to the mixture and stirred evenly, wherein the mass fraction of the transformer oil is 15-20%.

[0023] (3) After the mixed solution obtained in (2) is cooled to room temperature, it is ground to obtain grease.

[0024] Preferably, the base oil is any one of No. 20 transformer oil, cycloparaffin oil and ester oil. The oil temperature is raised to 100-110° C., and the mixture is allowed to stand for 30 minutes and then stirred. In the mixture of step (1), the mass fraction of the base oil is 40%, the mass fraction of the microcrystalline wax is 5%, the mass fraction of the polytetrafluoroethylene powder is 35%, and the mass fraction of petroleum ether is 1%.

[0025] Preferably, in step (2), the temperature of the oil bath heating is 80° C., the mass fraction of the ultrafine modified coal-based kaolinite-DMSO-CTAC is 1 to 2%, and the mass fraction of the transformer oil is 17 to 18%.

[0026] Therefore, the present invention has the following beneficial effects:

[0027] (1) The interlayer spacing of the novel grease additive prepared by the present invention through kaolinite modification will be significantly increased, so that more lubricant molecules can enter the interlayer, thereby improving the lubrication performance; and its surface properties are improved, which can reduce the hydrophilicity and enhance the lipophilicity inside the grease, which is conducive to better compatibility and mixing of other components in the lubricant.

[0028] (2) The grease material prepared by the present invention can remain intact and effectively prevent direct contact between friction surfaces under extreme conditions such as heavy load, high temperature, high pressure or impact load, thereby reducing friction, wear and damage and maintaining stable lubrication performance. This preparation method has advanced technology, detailed and accurate data, low energy consumption, and no pollution to the environment. It is an ideal method for preparing grease materials.

[0029] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 The XRD diagrams of the three stages in the preparation process of the ultrafine modified coal-based kaolinite-DMSO-CTAC intercalation compound in Example 1;

[0031] Figure 2 is a comparison of XRD patterns of ultrafine modified coal-based kaolinite-DMSO-CTAC intercalation compounds prepared under three different working conditions in Examples 1-3;

[0032] Figure 3 The figures are SEM images of kaolin powder before and after modification of the present invention; wherein, (a) is the SEM image of kaolin powder before modification, and (b) is the SEM image of kaolin powder after modification. DETAILED DESCRIPTION

[0033] The technical solution of the present invention is further described below through the accompanying drawings and embodiments.

[0034] Unless otherwise defined, technical or scientific terms used in the present invention shall have the common meanings understood by one having ordinary skills in the field to which the present invention belongs.

[0035] In addition, for the numerical range in the present invention, it is understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Each smaller range between the intermediate value in any stated value or stated range and any other stated value or intermediate value in the range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0036] In addition, it should be understood that although this specification is described according to the implementation modes, not every implementation mode includes only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation modes that can be understood by those skilled in the art. These other implementation modes are also covered within the protection scope of the present invention.

[0037] Example 1

[0038] This embodiment provides an ultrafine modified coal-based kaolinite-DMSO-CTAC intercalation compound and a grease prepared using the compound as an additive. The specific steps are as follows:

[0039] Deionized water was added to the kaolin raw material at a solid-liquid ratio of 1g:2ml and the mixture was fully stirred. The mixture was ultrasonically crushed at an ultrasonic power of 800w, an ultrasonic time of 2h and an ultrasonic frequency of 30kHz. After the crushing was completed, the intermediate product was obtained by drying. 10g of the intermediate product was weighed and dissolved in 10mL of a dimethyl sulfoxide mixed solution. The mixture was ultrasonically intercalated at an ultrasonic power of 150w, an ultrasonic time of 3h and an ultrasonic frequency of 8kHz. After the ultrasonication was completed, the mixture was centrifuged and dried to obtain an ultrafine coal-based kaolinite-DMSO intercalation complex, which was recorded as KA / DMSO.

[0040] Add hexadecyltrimethylammonium chloride C to the methanol solution 19 H 42 C l N, wherein the ratio of methanol to hexadecyltrimethylammonium chloride is 1 ml:9 g, to obtain a CTAC methanol solution, the molar concentration of which is 1 mol / L; taking a KA / DMSO intercalation complex and adding it to the CTAC methanol solution, wherein the solid-liquid ratio of the KA / DMSO intercalation complex to the CTAC methanol solution is 1 g:3 ml, after sufficient stirring, plasma ball milling is performed, the ball mill speed is 200 r / min, the ball milling time is 1.5 h, after the ball milling is completed, it is washed with a methanol solution and centrifuged and dried to obtain KA / DMSO-CTAC.

[0041] Microcrystalline wax (5wt%) is added as a dispersant to a base oil (40wt%); the oil temperature is increased to 100-110°C, and the mixture is stirred after standing for 30 minutes; polytetrafluoroethylene powder (35wt%) is added to the base oil and stirred evenly; the mixture is heated to 80°C in an oil bath in a beaker; after petroleum ether is completely volatilized, a KA / DMSO-CTAC additive (1wt%) and transformer oil (18wt%) are added to the mixture, and the temperature is maintained until the mixture is stirred evenly; the beaker is taken out of the oil bath, cooled to room temperature (24°C), and the mixture is ground three times with a three-roll mill to obtain a KA / DMSO-CTAC grease.

[0042] Example 2

[0043] This embodiment provides an ultrafine modified coal-based kaolinite-DMSO-CTAC intercalation compound and a grease prepared using the compound as an additive. The specific steps are as follows:

[0044] Deionized water was added to the kaolin raw material at a solid-liquid ratio of 1g:2ml and the material was fully stirred. The material was ultrasonically crushed at an ultrasonic power of 800w, an ultrasonic time of 2h and an ultrasonic frequency of 30kHz. After the crushing was completed, the intermediate product was obtained by drying. 10g of the intermediate product was weighed and dissolved in 10mL of a dimethyl sulfoxide mixed solution. The material was ultrasonically intercalated at an ultrasonic power of 200w, an ultrasonic time of 4h and an ultrasonic frequency of 10kHz. After the ultrasonic treatment was completed, the material was centrifuged and dried to obtain an ultrafine coal-based kaolinite-DMSO intercalation complex, which was recorded as KB / DMSO.

[0045] Add hexadecyltrimethylammonium chloride C to the methanol solution 19 H 42 C l N, wherein the ratio of methanol to hexadecyltrimethylammonium chloride is 1 ml:9 g, and a CTAC methanol solution is obtained, and the molar concentration of the solution is 1 mol / L; a certain amount of KB / DMSO intercalation complex is added to the CTAC methanol solution, wherein the solid-liquid ratio of KA / DMSO intercalation complex to CTAC methanol solution is 1 g:2 ml, and after sufficient stirring, plasma ball milling is performed, the ball mill speed is 250 r / min, and the ball milling time is 2 h. After the ball milling is completed, it is washed with a methanol solution and centrifuged and dried to obtain KB / DMSO-CTAC.

[0046] Microcrystalline wax (5wt%) is added as a dispersant to a base oil (40wt%); the oil temperature is increased to 100-110°C, and the mixture is stirred after standing for 30 minutes; polytetrafluoroethylene powder (35wt%) is added to the base oil and stirred evenly; the mixture is heated to 80°C in an oil bath in a beaker; after petroleum ether is completely volatilized, a KB / DMSO-CTAC additive (1wt%) and transformer oil (18wt%) are added to the mixture, and the temperature is maintained until the mixture is stirred evenly; the beaker is taken out of the oil bath, cooled to room temperature (24°C), and the mixture is ground three times with a three-roll mill to obtain a KB / DMSO-CTAC grease.

[0047] Example 3

[0048] This embodiment provides an ultrafine modified coal-based kaolinite-DMSO-CTAC intercalation compound and a grease prepared using the compound as an additive. The specific steps are as follows:

[0049] Deionized water was added to the kaolin raw material at a solid-liquid ratio of 1g:2ml and the mixture was fully stirred. The mixture was ultrasonically crushed at an ultrasonic power of 800w, an ultrasonic time of 2h and an ultrasonic frequency of 30kHz. After the crushing was completed, the intermediate product was obtained by drying. 10g of the intermediate product was weighed and dissolved in 10mL of a dimethyl sulfoxide mixed solution. The mixture was ultrasonically intercalated at an ultrasonic power of 250w, an ultrasonic time of 4h and an ultrasonic frequency of 12kHz. After the ultrasonication was completed, the mixture was centrifuged and dried to obtain an ultrafine coal-based kaolinite-DMSO intercalation complex, which was recorded as KC / DMSO.

[0050] Add hexadecyltrimethylammonium chloride C to the methanol solution 19 H 42 C l N, wherein the ratio of methanol to hexadecyltrimethylammonium chloride is 1 ml:9 g, and a CTAC methanol solution is obtained, and the molar concentration of the solution is 1 mol / L; a certain amount of KC / DMSO intercalation complex is added to the CTAC methanol solution, wherein the solid-liquid ratio of the KC / DMSO intercalation complex to the CTAC methanol solution is 1 g:2 ml (solid-liquid ratio is 1:2), and after sufficient stirring, plasma ball milling is performed, the ball mill speed is 300 r / min, and the ball milling time is 2 h. After the ball milling is completed, it is washed with a methanol solution and centrifuged and dried to obtain KC / DMSO-CTAC.

[0051] Microcrystalline wax (5wt%) is added as a dispersant to a base oil (40wt%); the oil temperature is increased to 100-110°C, and the mixture is stirred after standing for 30 minutes; polytetrafluoroethylene powder (35wt%) is added to the base oil and stirred evenly; the mixture is heated to 80°C in an oil bath in a beaker; after petroleum ether is completely volatilized, a KC / DMSO-CTAC additive (1wt%) and transformer oil (18wt%) are added to the mixture, and the temperature is maintained until the mixture is stirred evenly; the beaker is taken out of the oil bath, cooled to room temperature (24°C), and the mixture is ground three times with a three-roll mill to obtain a KC / DMSO-CTAC grease.

[0052] 1% by mass of original ultrafine coal-based kaolin and modified kaolin obtained by this technical solution were added to polytetrafluoroethylene grease, and the modified greases were named KA grease, KA / DMSO-CTAC grease (i.e., grease prepared in Example 1), KB / DMSO-CTAC grease (i.e., grease prepared in Example 2) and KC / DMSO-CTAC grease (i.e., grease prepared in Example 3). Polytetrafluoroethylene grease without ultrafine modified coal-based kaolinite-DMSO-CTAC intercalation compound is called base grease. The physical and chemical properties of the above samples were tested, and the results are shown in Table 1:

[0053] Table 1 Physical and chemical properties of grease

[0054]

[0055]

[0056] Comparative Example 1

[0057] This comparative example provides an ultrafine modified coal-based kaolinite-DMSO-CTAC intercalation compound and a grease prepared using the same as an additive. The ultrafine modified coal-based kaolinite-DMSO-CTAC intercalation compound is the same as the KA / DMSO-CTAC prepared in Example 1, except that the mass fraction of the additive in the grease KA / DMSO-CTAC prepared using the same as an additive is 1.5%, and the remaining steps are the same as in Example 1.

[0058] Comparative Example 2

[0059] This comparative example provides an ultrafine modified coal-based kaolinite-DMSO-CTAC intercalation compound and a grease prepared using the same as an additive. The ultrafine modified coal-based kaolinite-DMSO-CTAC intercalation compound is the same as the KA / DMSO-CTAC prepared in Example 1, except that the mass fraction of the additive in the grease KA / DMSO-CTAC prepared using the same as an additive is 2%, and the remaining steps are the same as in Example 1.

[0060] Table 2 Comparison of physical and chemical properties of KA / DMSO-CTAC grease

[0061]

[0062]

[0063] Comparative Example 3

[0064] This comparative example provides an ultrafine modified coal-based kaolinite-DMSO-CTAC intercalation compound and a grease prepared using the same as an additive. The ultrafine modified coal-based kaolinite-DMSO-CTAC intercalation compound is the same as the KB / DMSO-CTAC prepared in Example 2, except that the mass fraction of the additive in the grease KB / DMSO-CTAC prepared using the same as an additive is 1.5%, and the remaining steps are the same as in Example 2.

[0065] Comparative Example 4

[0066] This comparative example provides an ultrafine modified coal-based kaolinite-DMSO-CTAC intercalation compound and a grease prepared using the same as an additive. The ultrafine modified coal-based kaolinite-DMSO-CTAC intercalation compound is the same as the KB / DMSO-CTAC prepared in Example 2, except that the mass fraction of the additive in the grease KB / DMSO-CTAC prepared using the same as an additive is 2%, and the remaining steps are the same as in Example 2.

[0067] Table 3 Comparison of physical and chemical properties of KB / DMSO-CTAC grease

[0068]

[0069] Comparative Example 5

[0070] This comparative example provides an ultrafine modified coal-based kaolinite-DMSO-CTAC intercalation compound and a grease prepared using the same as an additive. The ultrafine modified coal-based kaolinite-DMSO-CTAC intercalation compound is the same as the KB / DMSO-CTAC prepared in Example 3, except that the mass fraction of the additive in the grease KB / DMSO-CTAC prepared using the same as an additive is 1.5%, and the remaining steps are the same as in Example 3.

[0071] Comparative Example 6

[0072] This comparative example provides an ultrafine modified coal-based kaolinite-DMSO-CTAC intercalation compound and a grease prepared using the same as an additive. The ultrafine modified coal-based kaolinite-DMSO-CTAC intercalation compound is the same as the KC / DMSO-CTAC prepared in Example 3, except that the mass fraction of the additive in the grease KC / DMSO-CTAC prepared using the same as an additive is 2%, and the remaining steps are the same as in Example 3.

[0073] Table 4 Comparison of physical and chemical properties of KC / DMSO-CTAC grease

[0074]

[0075] It can be seen from Table 1 that after adding the silicate material of coal-based kaolinite, the cone penetration of all four types of polytetrafluoroethylene greases has decreased. In particular, the cone penetration of KB / DMSO-CTAC grease and KC / DMSO-CTAC grease has decreased more significantly. It can also be clearly seen that the cone penetration of the silicate grease modified by ultrasonic intercalation of this technology has decreased more than that of the unmodified silicate grease. This shows that the addition of silicate materials increases the viscosity of the grease, and the thickening effect of the silicate material modified by ultrasonic intercalation is better than that of the unmodified material. Further observation shows that the grease with the addition of KB / DMSO-CTAC performs well in the sintering load test, with a load value of up to 5000N, which is significantly higher than other types of grease. This result shows that the addition of coal-based kaolin modified by ultrasonic intercalation of this technology significantly improves the extreme pressure properties of polytetrafluoroethylene grease.

[0076] At the same time, Tables 2-4 studied the effect of the amount of ultrafine modified coal-based kaolinite-DMSO-CTAC intercalation compounds prepared in Examples 1-3 on the physical and chemical properties of greases when used as additives to prepare greases. The experimental results show that when KA / DMSO-CTAC, KB / DMSO-CTAC, and KC / DMSO-CTAC additives are added at mass fractions of 1%, 1.5%, and 2%, respectively, the dropping point temperatures of the three greases are increased compared with the base grease and KA grease, among which the dropping point temperature increase when the mass fraction of the additive is 1.5% is greater than that of the additives at mass fractions of 1% and 2%; similarly, the cone penetration of the three greases is decreased compared with the base grease and KA grease, among which 1.5% KA / DMSO-CTAC, 1.5% KB / DMSO-CTAC The decrease in grease cone penetration is greater than that of greases with mass fractions of 1% and 2%, while the effect of KC / DMSO-CTAC when added at mass fractions of 1% and 1.5% is equal, both higher than that of 2% grease; similarly, the sintering loads of the three greases are increased compared with the base grease and KA grease. When the additive is KA / DMSO-CTAC, the increase in the sintering loads of the three greases with different mass fractions is the same. When the additive is KB / DMSO-CTAC, the increase in the sintering load of the greases with mass fractions of 1% and 1.5% is greater than that of the grease with mass fraction of 2%. When the additive is KC / DMSO-CTAC, the effect is similar to that of the KB / DMSO-CTAC additive, and the increase in the sintering load of the greases with mass fractions of 1% and 1.5% is greater than that of the grease with mass fraction of 2%.

[0077] When KB / DMSO-CTAC is added at a mass fraction of 1.5%, the dropping point temperature of the prepared polytetrafluoroethylene grease is as high as 341°C, compared with 329°C of the base grease, and its high temperature resistance is improved; the 1 / 4 cone penetration of the 1.5% KB / DMSO-CTAC grease is 68.8 (0.1mm), compared with 74.5 (0.1mm) of the base grease, the cone penetration decreases, which means that the prepared 1.5% KB / DMSO-CTAC grease has higher plasticity and anti-extrusion ability than the base grease, and is more suitable for high temperature and high load scenarios; the sintering load of the 1.5% KB / DMSO-CTAC grease is 5000N, compared with 4000N of the base grease, which is a large increase, which means that the stability of the grease lubrication effect under extreme conditions such as high temperature and heavy load is greatly improved.

[0078] In summary, by adding intercalated modified kaolin additives prepared by this technology into polytetrafluoroethylene grease and improving production process parameters and other effective means, the extreme pressure properties of polytetrafluoroethylene grease can be significantly enhanced, making it exhibit more excellent lubrication effect and durability under extreme working conditions.

[0079] Figure 1 The XRD patterns of the three stages of the preparation process of the ultrafine modified coal-based kaolinite-DMSO-CTAC intercalation compound in Example 1 are the original pattern of coal-based kaolinite (KA), the XRD patterns of kaolinite subjected to ultrasonic assisted intercalation (KA / DMSO), and the XRD patterns of intercalation exfoliation (KA / DMSO-CTAC). Figure 1 As shown in the figure, under the assistance of ultrasound, the ultrafine coal-based kaolin was first intercalated with dimethyl sulfoxide (DMSO), and then hexadecyltrimethylammonium chloride (CTAC) was introduced into it for plasma ball milling and exfoliation. It can be seen that after the insertion of the precursor DMSO, the interlayer spacing increased, and then the plasma ball milling and exfoliation with CTAC methanol solution was further improved.

[0080] Figure 2 1 is a comparison of XRD patterns of ultrafine modified coal-based kaolinite-DMSO-CTAC intercalation compounds prepared under three different working conditions in Examples 1-3. Figure 2 It can be seen that the modified kaolinite under the KB / DMSO-CTAC working condition achieves the best intercalation rate, indicating that the effect of ultrasonic time on the intercalation rate is more significant. With the increase of ultrasonic-assisted intercalation time, the intercalation rate is significantly improved. Compared with other intercalation methods, ultrasonic-assisted intercalation can greatly improve the intercalation rate of kaolin in a short time and achieve rapid intercalation of kaolin.

[0081] Figure 3 The original image of coal-based kaolin and the SEM image of kaolin modified by ultrasonic intercalation in Example 2 are shown in FIG. Figure 3 It can be seen that Figure 3 (a) The crystal shape of raw kaolin is mainly irregular flaky, containing a small amount of tubular structure. Figure 3 (b) The lamellar structure of kaolin modified by ultrasonic intercalation is generally fragmented, with only a small number of large lamellar structures remaining, and the edges are fragmented. The overall fragmentation trend is also present, and the grain thickness is significantly reduced. Due to the fragmentation and edge fragmentation of the kaolin lamellar structure during the ultrasonic intercalation modification process, the specific surface area and pore size of the modified sample are greatly increased.

[0082] Therefore, the present invention provides an ultrafine modified coal-based kaolinite-DMSO-CTAC intercalation compound and a preparation method and application thereof. Coal-based kaolinite, dimethyl sulfoxide and hexadecyltrimethylammonium chloride are used as raw materials. A novel grease additive is prepared by ultrasonically crushing the coal-based kaolinite, configuring an intercalation agent in proportion, ultrasonically intercalating the ultrafine coal-based kaolinite, and plasma ball milling and peeling the ultrafine modified coal-based kaolinite. The interlayer spacing of the additive will be significantly increased, so that more lubricant molecules can enter the interlayer, thereby improving the lubrication performance; and its surface properties are improved, so that the hydrophilicity of the inside of a novel grease material made of polytetrafluoroethylene is weakened and the lipophilicity is enhanced, which is conducive to better compatibility and mixing of other components in the lubricant.

[0083] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing an ultrafine modified coal-based kaolinite-DMSO-CTAC intercalation compound, characterized in that: The following steps are involved: S1. preparing a mixed material: adding deionized water to the coal-based kaolin raw material, stirring sufficiently to make the coal-based kaolin evenly dispersed in the deionized water to prepare a mixed material; S2. Ultrasonic crushing of coal-based kaolin: Put the mixed material prepared in S1 into an ultrasonic cell disruptor to complete ultrasonic crushing of the coal-based kaolin, wash it with ethanol, and obtain ultrafine coal-based kaolin after centrifugal drying; S3, preparation of ultrafine coal-based kaolinite / DMSO intercalation complex: dissolving the ultrafine coal-based kaolinite prepared in S2 in deionized water from which CO2 has been removed to prepare a mixed solution; S4, adding dimethyl sulfoxide to the mixed solution prepared in S3 to prepare an ultrafine coal-based kaolinite / DMSO suspension; S5. Place the beaker containing the ultrafine coal-bearing kaolinite / DMSO suspension into an ultrasonic cell disruptor to intercalate the ultrafine coal-bearing kaolinite: extend the ultrasonic probe below the liquid surface, 10 to 15 mm from the bottom of the cup, to complete the ultrasonic intercalation of the coal-bearing kaolinite; S6, adding anhydrous ethanol to the suspension prepared in S5 to wash the dimethyl sulfoxide remaining on the surface of the kaolinite, and obtaining an ultrafine coal-based kaolinite / DMSO intercalation complex after separation and drying; S7, adding hexadecyltrimethylammonium chloride to the methanol solution to obtain a CTAC methanol solution, adding the ultrafine coal-based kaolinite / DMSO intercalation complex thereto, and blending and stirring; S8. The slurry prepared in S7 is subjected to plasma ball milling treatment. After the treatment, the CTAC remaining on the surface is washed off with a methanol solution, and ultrafine modified coal-based kaolinite-DMSO-CTAC is obtained by separation and drying.

2. The method for preparing an ultrafine modified coal-based kaolinite-DMSO-CTAC intercalation compound according to claim 1, characterized in that: In step S1, the solid-liquid ratio of coal-based kaolin and deionized water is 1g:(1-3)ml. In step S2, the ultrasonic power is 600-1000w, the ultrasonic time is 1-3h, and the ultrasonic frequency is 10-30kHz.

3. The method for preparing an ultrafine modified coal-based kaolinite-DMSO-CTAC intercalation compound according to claim 1, characterized in that: In step S4, the mass volume ratio of the mixed solution to dimethyl sulfoxide is 1g:(7-10)ml. In step S5, the ultrasonic power is 150w-250w, the ultrasonic time is 3-5h, and the ultrasonic frequency is 8-12kHz.

4. The method for preparing an ultrafine modified coal-based kaolinite-DMSO-CTAC intercalation compound according to claim 1, characterized in that: In step S7, the concentration of hexadecyltrimethylammonium chloride in the CTAC methanol solution after mixing is 0.5-1 mol / L, and the solid-liquid ratio of the ultrafine coal-based kaolinite / DMSO intercalation complex to the CTAC methanol solution is 1 g:(2-4) ml.

5. The method for preparing an ultrafine modified coal-based kaolinite-DMSO-CTAC intercalation compound according to claim 1, characterized in that: In step S8, the ball mill speed is 200-300 r / min, and the ball milling time is 1-3 h.

6. An ultrafine modified coal-based kaolinite-DMSO-CTAC intercalation compound, characterized in that: The ultrafine modified coal-based kaolinite-DMSO-CTAC intercalation compound is prepared by the preparation method of any one of claims 1 to 5.

7. An application of the ultrafine modified coal-based kaolinite-DMSO-CTAC intercalation compound as claimed in claim 6, characterized in that: Ultrafine modified coal-based kaolinite-DMSO-CTAC intercalation compounds are used as additives in the preparation of greases with high load-bearing capacity and extreme pressure resistance.

8. The use of an ultrafine modified coal-based kaolinite-DMSO-CTAC intercalation compound according to claim 7, characterized in that: The specific preparation steps of grease are as follows: (1) Add microcrystalline wax as a dispersant to the base oil, heat to 100-110° C., stand for 30 minutes and then stir, add polytetrafluoroethylene powder and petroleum ether and stir; (2) heating the mixture prepared in (1) in an oil bath in a beaker until the petroleum ether is completely volatilized, adding ultrafine modified coal-based kaolinite-DMSO-CTAC and a certain amount of transformer oil to the mixture and stirring evenly; (3) After the mixed solution obtained in (2) is cooled to room temperature, it is ground to obtain grease.

9. The use of an ultrafine modified coal-based kaolinite-DMSO-CTAC intercalation compound according to claim 8, characterized in that: The base oil is any one of No. 20 transformer oil, cycloparaffin oil and ester oil. The oil temperature is raised to 100-110° C., and the mixture is stirred after standing for 30 minutes. In the mixture of step (1), the mass fraction of the base oil is 40%, the mass fraction of the microcrystalline wax is 5%, the mass fraction of the polytetrafluoroethylene powder is 35%, and the mass fraction of petroleum ether is 2%.

10. The use of an ultrafine modified coal-based kaolinite-DMSO-CTAC intercalation compound according to claim 8, characterized in that: In step (2), the temperature of the oil bath heating is 80° C., the mass fraction of the ultrafine modified coal-based kaolinite-DMSO-CTAC is 1-2%, and the mass fraction of the transformer oil is 18%.

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