Preparation method of polytetrafluoroethylene / polystyrene composite microspheres used as solid lubricant

Abstract

The invention discloses a preparation method of polytetrafluoroethylene / polystyrene composite microspheres used as a solid lubricant, belonging to the technical field of water-based lubricating additives. In the invention, an oil-phase solution obtained by mixing styrene monomer, a cross-linking agent and an initiator is mixed with an aqueous-phase solution obtained by mixing polytetrafluoroethylene and a dispersant solution, and is stirred and reacted at a certain temperature, washed and dried to obtain the polytetrafluoroethylene / polystyrene composite microspheres. Polytetrafluoroethylene itself has good self-lubricating performance. The composite microspheres can convert sliding friction into rolling friction, and the polytetrafluoroethylene / polystyrene composite microspheres can form a protective transfer film on the friction surface. Therefore, the polytetrafluoroethylene / polystyrene composite microspheres prepared by the invention have excellent friction reduction and wear resistance effects as water-based solid lubricants.

Description

Technical Field

[0001] The present invention belongs to the technical field of water-based lubricating additives, and particularly relates to a preparation method of polytetrafluoroethylene / polystyrene composite microspheres used as solid lubricants. Background Art

[0002] With the development of modern industry, friction and wear are involved in all aspects of industrial society, such as machinery, chemical engineering, oil drilling, etc. In the oil drilling industry, as the drilling depth becomes deeper and deeper, the difficulty also becomes greater, and it is very easy to occur stuck pipe accidents during the drilling process. In order to reduce the damage of the friction surface during relative movement, it is necessary to use powdery or film-like solids on the surface, which are called solid lubricants. Currently, common solid lubricants in the oil drilling industry include graphite, molybdenum disulfide, hollow microspheres, and polystyrene microspheres, etc. Graphite and molybdenum disulfide have low density and are easy to float on the water surface, with low utilization rate; hollow microspheres have low bearing capacity and are easy to break.

[0003] Polystyrene microspheres are an efficient solid lubricant for drilling fluids, with characteristics such as non-fluorescent, non-toxic, and not reacting chemically with any components in the drilling fluid. However, pure polystyrene microsphere materials do not have self-lubricating properties, thus affecting their lubrication effect. Summary of the Invention

[0004] Aiming at the deficiencies of the above-mentioned prior art, the present invention provides a preparation method of polytetrafluoroethylene / polystyrene composite microspheres used as solid lubricants. Using styrene as the raw material and polytetrafluoroethylene with excellent self-lubricating performance as the additive, the lubrication effect is improved by the composite method of the two.

[0005] To achieve the above object, the present invention proposes the following technical solutions:

[0006] A preparation method of polytetrafluoroethylene / polystyrene composite microspheres, comprising the following steps:

[0007] Mix styrene, cross-linking agent and initiator to obtain an oil-phase solution;

[0008] Mix polytetrafluoroethylene and dispersant solution to obtain an aqueous-phase solution;

[0009] Mix the obtained oil-phase solution and aqueous-phase solution for reaction, and filter, wash and dry the obtained product to obtain polytetrafluoroethylene / polystyrene composite microspheres.

[0010] Furthermore, the mass ratio of the styrene, cross-linking agent, initiator and polytetrafluoroethylene is (10 - 30):(1 - 5):(0.2 - 1.2):(0.1 - 1).

[0011] Further, the cross-linking agent is one or more of divinylbenzene, diisocyanate, N,N-methylenebisacrylamide, and acrylic acid; the initiator is one or more of benzoyl peroxide, azobisisobutyronitrile, and acetyl peroxide; the polytetrafluoroethylene is a polytetrafluoroethylene dispersion with a solid content of 60%.

[0012] Further, the dispersant solution is an aqueous dispersant solution, and the mass ratio of the dispersant to water is 1:(40 - 200).

[0013] Further, the dispersant is one or more of polyvinyl alcohol, polyvinylpyrrolidone, sodium polymethacrylate, and hydroxypropyl cellulose.

[0014] Further, the volume ratio of the oil phase solution to the water phase solution during mixing is 1:(3 - 5).

[0015] Further, the reaction temperature is 60 - 90°C, the reaction time is 7 - 10 h, and the stirring speed is 300 - 500 rpm.

[0016] Further, during the washing process, the solvents used are deionized water and absolute ethanol.

[0017] The present invention also provides a polytetrafluoroethylene / polystyrene composite microsphere prepared by using the above preparation method, and the particle size of the polytetrafluoroethylene / polystyrene composite microsphere is 20 - 200 μm.

[0018] The present invention also provides a solid lubricant prepared by using the polytetrafluoroethylene / polystyrene composite microspheres.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0020] The preparation method of the polytetrafluoroethylene / polystyrene composite microspheres provided by the present invention has good heat dissipation and a stable reaction throughout the process. The reaction process is safe and harmless, the operation is simple, and it is easier to achieve large-scale production compared with the existing technologies.

[0021] The polytetrafluoroethylene / polystyrene composite microspheres prepared by the present invention have the lubrication performance of polytetrafluoroethylene itself, can convert sliding friction into rolling friction, reduce the friction resistance, etc., and can form a protective lubricating transfer film on the friction surface, avoiding the direct contact of the friction pair, and playing a good role in reducing friction and wear. Therefore, it has excellent lubrication effects and broad industrial prospects. Description of the Drawings

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the accompanying drawings required in the embodiments. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can be obtained based on these drawings.

[0023] Figure 1 Scanning electron micrograph of the polytetrafluoroethylene / polystyrene composite microspheres prepared in Example 1;

[0024] Figure 2 Scanning electron micrograph of the polytetrafluoroethylene / polystyrene composite microspheres prepared in Example 2;

[0025] Figure 3 Scanning electron micrograph of the polytetrafluoroethylene / polystyrene composite microspheres prepared in Example 3;

[0026] Figure 4 Scanning electron micrograph of the polytetrafluoroethylene / polystyrene composite microspheres prepared in Example 4;

[0027] Figure 5 Coefficient of friction graph of the polytetrafluoroethylene / polystyrene composite microspheres and pure polystyrene microspheres prepared in Examples 1, 2, 3, and 4;

[0028] Figure 6 Wear volume graph of the polytetrafluoroethylene / polystyrene composite microspheres and pure polystyrene microspheres prepared in Examples 1, 2, 3, and 4. Detailed implementation manners

[0029] Now, various exemplary implementation manners of the present invention will be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, characteristics, and implementation schemes of the present invention.

[0030] It should be understood that the terms described in the present invention are only for describing specific implementation manners and are not used to limit the present invention. Additionally, for the numerical ranges in the present invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Each intermediate value within any stated value or stated range, as well as each smaller range between any other stated value or intermediate value within the stated range, is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded from the range.

[0031] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Although this invention only describes preferred methods and materials, any methods and materials similar or equivalent to those described herein can also be used in the implementation or testing of this invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the said documents. In case of conflict with any incorporated document, the content of this specification shall prevail.

[0032] Without departing from the scope or spirit of this invention, various improvements and changes can be made to the specific embodiments of the description of this invention, which are obvious to those skilled in the art. Other embodiments obtained from the description of this invention are obvious to those skilled in the art. The description and examples of this application are merely exemplary.

[0033] Regarding the use of "comprising", "including", "having", "containing", etc. in this article, they are all open-ended terms, meaning including but not limited to.

[0034] The "normal temperature" referred to in this invention is 25 °C.

[0035] The raw material styrene used in this invention is purchased from Tianjin Yongda Chemical Reagent, the crosslinking agent, initiator and dispersant are all purchased from Shanghai Macklin Biochemical Technology, and the polytetrafluoroethylene is purchased from Aladdin Biochemical Technology, all of which are commercially available.

[0036] Polytetrafluoroethylene is a high molecular polymer obtained by polymerizing tetrafluoroethylene as a monomer, and has the characteristic of high temperature resistance. Its friction coefficient is extremely low, so it can be used as an additive with excellent self-lubricating performance.

[0037] A method for preparing polytetrafluoroethylene / polystyrene composite microspheres, comprising the following steps:

[0038] Mix styrene, crosslinking agent and initiator to obtain an oil-phase solution;

[0039] Mix polytetrafluoroethylene and dispersant solution to obtain an aqueous-phase solution;

[0040] Mix the obtained oil-phase solution and aqueous-phase solution for reaction, and perform suction filtration, washing and drying on the obtained product to obtain polytetrafluoroethylene / polystyrene composite microspheres.

[0041] In some preferred embodiments, the mass ratio of the styrene, crosslinking agent, initiator and polytetrafluoroethylene is (10 - 30):(1 - 5):(0.2 - 1.2):(0.1 - 1); preferably 18:2:0.36:0.8.

[0042] In some preferred embodiments, the crosslinking agent is one or more of divinylbenzene, diisocyanate, N,N-methylenebisacrylamide, and acrylic acid; preferably divinylbenzene.

[0043] The initiator is one or more of benzoyl peroxide, azobisisobutyronitrile, and acetyl peroxide; preferably benzoyl peroxide.

[0044] The polytetrafluoroethylene in the embodiments of the present invention is a polytetrafluoroethylene dispersion with a solid content of 60%.

[0045] In some preferred embodiments, the dispersant solution is an aqueous dispersant solution, and the mass ratio of the dispersant to water is 1:(40 - 200).

[0046] In some preferred embodiments, the dispersant is one or more of polyvinyl alcohol, polyvinylpyrrolidone, sodium polymethacrylate, and hydroxypropyl cellulose; preferably polyvinyl alcohol.

[0047] In some preferred embodiments, the volume ratio of the oil phase solution to the water phase solution is 1:(3 - 5); preferably 1:3.

[0048] In some preferred embodiments, the reaction temperature is 60 - 90 °C (preferably 80 °C), the reaction time is 7 - 10 h (preferably 8 h), and the stirring speed is 300 - 500 rpm (preferably 500 rpm).

[0049] In some preferred embodiments, during the washing process, the reaction product is suction filtered and washed with deionized water and absolute ethanol multiple times to remove unreacted impurities; then the washed product is vacuum dried to obtain polytetrafluoroethylene / polystyrene composite microspheres. The temperature of vacuum drying is 30 - 50 °C, and the time is 24 - 48 h.

[0050] The present invention also provides a polytetrafluoroethylene / polystyrene composite microsphere prepared by the above preparation method.

[0051] The present invention also provides a solid lubricant prepared by using the polytetrafluoroethylene / polystyrene composite microspheres.

[0052] Example 1

[0053] 1) Take 18 g of styrene, 2 g of divinylbenzene, and 0.36 g of benzoyl peroxide, and stir until completely dissolved as the oil phase;

[0054] 2) Preparation of dispersant solution: Slowly and gradually add 2 g of polyvinyl alcohol into a dissolution kettle filled with deionized water at room temperature, while stirring at a rate of 100 rpm. After stirring for 30 min, gradually heat up to 80 °C and maintain until the dispersant is completely dissolved; Take 80 mL of the prepared polyvinyl alcohol solution and dilute it to 100 mL with deionized water;

[0055] 3) Add 0.8 g of polytetrafluoroethylene dispersion into the diluted polyvinyl alcohol solution and mix evenly by ultrasonic as the aqueous phase;

[0056] 4) Mix the aqueous phase and the oil phase in a volume ratio of 3:1, stir at a speed of 500 rpm, and heat at a constant temperature of 80 °C for polymerization reaction.

[0057] 5) Take the product after 8 h of reaction, filter and wash it with deionized water and ethanol respectively, and vacuum dry the washed product to obtain polytetrafluoroethylene / polystyrene composite microspheres.

[0058] Figure 1 This is the scanning electron microscope image of the polytetrafluoroethylene / polystyrene composite microspheres prepared in this example. It can be seen that the prepared product is in good spherical shape.

[0059] Comparative Example 1

[0060] Pure polystyrene microspheres, namely PS microspheres, were prepared in the same way as in Example 1, except that in step 3), no polytetrafluoroethylene dispersion was added to the aqueous solution.

[0061] The friction and wear performance of the polytetrafluoroethylene / polystyrene composite microspheres and PS microspheres prepared in Example 1 were tested and compared.

[0062] The specific performance test method is as follows: The microspheres were evenly dispersed in deionized water by ultrasonic, and the mass ratio of microspheres to water was 4:100. The friction and wear performance was tested using a domestic HSR-2M reciprocating friction testing machine. The friction machine reciprocated in a ball-on-disk contact mode. The static upper specimen was a silicon nitride ball with a diameter of 4 mm, and the reciprocating sliding lower specimen was a polished 304 stainless steel sheet. The normal load for testing was 10 N, the reciprocating motion amplitude was 20 mm, the friction duration was 10 min, and each group of tests was repeated 3 times and the average value was taken. A P-6 step film thickness gauge was used to observe the wear marks left on the substrate after reciprocating friction in the friction experiment, and each group of specimens was tested 3 times and the average value was taken.

[0063] The friction test results are as Figure 5 shown, and the wear test results are as Figure 6As shown. It can be seen that due to the addition of polytetrafluoroethylene material with excellent self-lubricating performance, the lubricating performance of the polytetrafluoroethylene / polystyrene composite microspheres prepared in Example 1 of the present invention is better and more wear-resistant. The friction coefficient of the polytetrafluoroethylene / polystyrene composite microspheres prepared in Example 1 is 0.213, which is only 34% of that of the PS microspheres; the wear volume is 2.45×10 -4 mm 3 , which is 10% of that of the PS microspheres.

[0064] Example 2

[0065] As a comparative example of Example 1, the implementation steps are the same as those of Example 1, except that in step 3), 0.6 g of polytetrafluoroethylene dispersion is added to the diluted polyvinyl alcohol solution.

[0066] Figure 2 This is the scanning electron microscope image of the polytetrafluoroethylene / polystyrene composite microspheres prepared in this example. It can be seen that the prepared product is in good spherical shape.

[0067] The test method is the same as that of Example 1, and the results are as shown in Figure 5 and Figure 6 . The friction coefficient of the prepared polytetrafluoroethylene / polystyrene composite microspheres is 0.233, and the wear volume is 3.02×10 -4 mm 3 .

[0068] Example 3

[0069] As a comparative example of Example 1, the implementation steps are the same as those of Example 1, except that in step 2), 20 mL of the prepared polyvinyl alcohol solution is taken and diluted to 100 mL with deionized water.

[0070] Figure 3 This is the scanning electron microscope image of the polytetrafluoroethylene / polystyrene composite microspheres prepared in this example. It can be seen that the prepared product is in good spherical shape.

[0071] The test method is the same as that of Example 1, and the results are as shown in Figure 5 and Figure 6 . The friction coefficient of the prepared polytetrafluoroethylene / polystyrene composite microspheres is 0.258, and the wear volume is 3.5×10 -4 mm 3 .

[0072] Example 4

[0073] As a comparative example of Example 1, the implementation steps are the same as those of Example 1, except that in step 4), the stirring speed is 300 rpm.

[0074] Figure 4Scanning electron micrograph of the polytetrafluoroethylene / polystyrene composite microspheres prepared in this example. It can be seen that the prepared product is in good spherical shape.

[0075] The results are as Figure 5 and Figure 6 , the friction coefficient of the prepared polytetrafluoroethylene / polystyrene composite microspheres is 0.313, and the wear volume is 4.23×10 -4 mm 3 .

[0076] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for preparing polytetrafluoroethylene / polystyrene composite microspheres, characterized in that, It includes the following steps: Mix styrene, a crosslinking agent and an initiator to obtain an oil-phase solution; Mix polytetrafluoroethylene and a dispersant solution to obtain an aqueous-phase solution; Mix the obtained oil-phase solution and aqueous-phase solution for reaction, and perform suction filtration, washing and drying on the obtained product to obtain polytetrafluoroethylene / polystyrene composite microspheres; The mass ratio of the styrene, crosslinking agent, initiator and polytetrafluoroethylene is (10 - 30):(1 - 5):(0.2 - 1.2):(0.1 - 1); The dispersant solution is an aqueous dispersant solution, and the mass ratio of the dispersant to water is 1:(40 - 200); The volume ratio of the oil-phase solution to the aqueous-phase solution during mixing is 1:(3 - 5); The reaction temperature is 60 - 90°C, the reaction time is 7 - 10 h, and the stirring speed is 300 - 500 rpm.

2. The preparation method of the polytetrafluoroethylene / polystyrene composite microspheres according to claim 1, wherein, The crosslinking agent is one or more of divinylbenzene, diisocyanate and N,N-methylenebisacrylamide; the initiator is one or more of benzoyl peroxide, azobisisobutyronitrile and acetyl peroxide.

3. The preparation method of the polytetrafluoroethylene / polystyrene composite microspheres according to claim 1, characterized in that, The dispersant is one or more of polyvinyl alcohol, polyvinylpyrrolidone, sodium polymethacrylate and hydroxypropyl cellulose.

4. The preparation method of the polytetrafluoroethylene / polystyrene composite microspheres according to claim 1, characterized in that, During the washing process, the solvents used are deionized water and absolute ethanol.

5. Polytetrafluoroethylene / polystyrene composite microspheres prepared by the preparation method of the polytetrafluoroethylene / polystyrene composite microspheres according to any one of claims 1 - 4.

6. A solid lubricant, characterized in that, Prepared by using the polytetrafluoroethylene / polystyrene composite microspheres according to claim 5.

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