Polyurea-imide prepolymer and peek / ptfe self-lubricating fiber fabric composites, and preparation and application thereof
By introducing a microphase separation structure of urea groups and alkyl chains into the polymer, the problem of poor adhesion of fluorinated polyimide resin was solved, and a polyurea-imide prepolymer with excellent adhesion and high temperature resistance under normal pressure was prepared. This prepolymer was then applied to self-lubricating fiber fabric composites, improving the stability and lifespan of components such as bearings.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- LANZHOU INSTITUTE OF CHEMICAL PHYSICS CHINESE ACADEMY OF SCIENCES
- Filing Date
- 2024-09-18
- Publication Date
- 2026-07-21
AI Technical Summary
Existing fluorinated polyimide resins are prone to breakage during imidization, resulting in poor adhesion and inability to be effectively bonded to the bearing wall. Furthermore, the adhesion performance of fluorinated polyimide cured under normal pressure is not ideal, making it difficult to meet the requirements of high-speed self-lubricating gaskets.
By using the polymerization reaction of diamine and fluorine-containing elements in dianhydride, urea groups and alkyl chains are introduced to form a polyurea-imide prepolymer with a microphase separation structure. Through the biomimetic dragonfly wing structure design, the adhesive properties and high temperature resistance of the resin are improved, and green organic solvents are used to reduce environmental impact.
A polyurea-imide prepolymer with excellent adhesion and high-temperature resistance under normal pressure was prepared, which improved the mechanical and tribological properties of PEEK/PTFE self-lubricating fiber fabric composites and extended the service stability and service life of moving parts.
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Figure CN119320496B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of lubrication materials technology, and in particular to polyurea-imide prepolymers and PEEK / PTFE self-lubricating fiber fabric composites, their preparation and application. Background Technology
[0002] Bearings are crucial basic components in mechanical equipment, primarily serving to support transmission and reduce frictional resistance during relative motion of contacting moving parts. With the rapid development of high-tech equipment, the service environment and operating conditions of bearings are becoming increasingly demanding. Fiber-reinforced polymer matrix composites, possessing unique advantages such as low thickness, excellent dimensional stability, strong load-bearing capacity, and high designability, have been widely used as lubricating layers in bearings in fields such as aviation, aerospace, and shipbuilding.
[0003] In recent years, the demand for high-speed self-lubricating gaskets has been increasing. Under high-speed operating conditions, gasket materials must be able to withstand higher frictional heat and stress concentration, requiring materials with better thermal stability and wear resistance. Furthermore, bearings are often three-dimensional curved surfaces, therefore self-lubricating fabric gaskets are mostly manufactured using hand lay-up processes and cured under normal or low pressure. To meet the performance requirements of gasket materials, the selection of the polymer matrix for fiber-woven composites is crucial. Polyimide resins have advantages such as high temperature resistance and strong mechanical properties, with fluorinated polyimides exhibiting superior high-temperature resistance. However, excessively high fluorine content in the molecular chain leads to high electronegativity in the polymer molecules, causing them to break during imidization and exhibiting no adhesion, making it impossible to bond the fabric to the bearing wall for friction reduction and lubrication. Even with low fluorine content, the adhesion performance of fluorinated polyimides cured under normal pressure is not ideal. Summary of the Invention
[0004] In view of this, the object of the present invention is to provide a polyurea-imide prepolymer and a PEEK / PTFE self-lubricating fiber fabric composite material, as well as the preparation and application thereof. The polyurea-imide prepolymer prepared by the present invention has both excellent adhesive properties and high-temperature resistance, enabling the PEEK / PTFE self-lubricating fiber fabric to possess excellent adhesive tensile properties and tribological properties.
[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution:
[0006] This invention provides a method for preparing a polyurea-imide prepolymer, comprising the following steps:
[0007] A polymerization reaction was carried out by mixing diamine, diisocyanate and organic solvent to obtain a small molecule with diamine-terminated urea group;
[0008] The diamine-terminated urea-containing small molecules are mixed with dianhydride and subjected to a polycondensation reaction to obtain the polyurea-imide prepolymer; at least one of the diamine and dianhydride contains fluorine, and the diisocyanate contains an alkyl chain.
[0009] Preferably, the diamine comprises one or more of 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane, 2,2'-bis(trifluoromethyl)diaminobiphenyl, 2,2-bis(4-aminophenyl)hexafluoropropane, 2,2-bis(3-(3-aminobenzoylamino)-4-hydroxyphenyl)hexafluoropropane, 2-(4-aminophenyl)-5-aminobenzimidazole, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfone, and biphenyl diamine.
[0010] Preferably, the diisocyanate includes one or more of hexamethylene diisocyanate, isophorone diisocyanate, trans-1,4-cyclohexyl diisocyanate and lysine diisocyanate; the molar ratio of the diisocyanate to the diamine is (0.1-1.0):1.0.
[0011] Preferably, the dianhydride comprises one or more of pyromellitic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 3,3',4,4'-benzophenone tetracarboxylic dianhydride, 3,3',4,4'-diphenyl ether tetracarboxylic dianhydride, and hexafluoroisopropylphthalic anhydride; the molar ratio of the dianhydride to the diamine is (0.1-1.0):1.0.
[0012] Preferably, the organic solvent includes one or more of N,N-dimethylacetamide, N,N-dimethylformamide, dimethyl sulfoxide, N-methylpyrrolidone, dihydro-L-glucosinolate, isosorbide dimethyl ether, soybean oil fatty acid methyl ester, lactate, and D-limonene.
[0013] Preferably, the polymerization reaction is carried out at a temperature of 50–60°C for 5–9 hours; the polycondensation reaction is carried out at a temperature of 0–5°C for 10–14 hours; both the polymerization and polycondensation reactions are carried out under a protective atmosphere.
[0014] The present invention provides a polyurea-imide prepolymer prepared by the preparation method described in the above technical solution.
[0015] This invention provides a PEEK / PTFE self-lubricating fiber fabric composite material, comprising a PEEK / PTFE self-lubricating fiber fabric and a polyurea-imide resin composited on the PEEK / PTFE self-lubricating fiber fabric, wherein the polyurea-imide resin is cured from the polyurea-imide prepolymer described in the above technical solution.
[0016] This invention provides a method for preparing the PEEK / PTFE self-lubricating fiber fabric composite material described in the above technical solution, comprising the following steps:
[0017] PEEK / PTFE self-lubricating fiber fabric is impregnated in the polyurea-imide prepolymer to obtain PEEK / PTFE self-lubricating fiber fabric prepreg.
[0018] The PEEK / PTFE self-lubricating fiber fabric prepreg is bonded to the surface of the substrate and cured to obtain the PEEK / PTFE self-lubricating fiber fabric composite material.
[0019] This invention provides the application of the PEEK / PTFE self-lubricating fiber fabric composite material described in the above technical solutions or the PEEK / PTFE self-lubricating fiber fabric composite material prepared by the above technical solutions in the field of lubrication.
[0020] This invention provides a method for preparing a polyurea-imide prepolymer, comprising the following steps: mixing a diamine, a diisocyanate, and an organic solvent for polymerization to obtain a diamine-terminated urea-containing small molecule; mixing the diamine-terminated urea-containing small molecule with a dianhydride for polycondensation to obtain the polyurea-imide prepolymer; wherein at least one of the diamine and the dianhydride contains fluorine, and the diisocyanate contains an alkyl chain. This invention utilizes a biomimetic dragonfly wing structure to design the resin's hard and soft segments. By introducing urea groups into the molecular chain of the fluorinated polyimide through the addition of diisocyanate, the adhesive properties of the resin are improved. Furthermore, in the polyimide, the diamine and dianhydride constitute the hard segments of the molecular chain, while the alkane-containing diisocyanate constitutes the soft segments. This design enables microphase separation, and the microphase separation structure significantly improves the mechanical properties and thermal stability of the material. The polyurea-imide prepolymer prepared by this invention is prepared and cured under normal pressure, and has both excellent adhesion and high temperature resistance, which can significantly improve the mechanical and tribological properties of self-lubricating fiber fabric composites.
[0021] Furthermore, without affecting the properties of the generated resin, this invention achieves the replacement of highly toxic solvents with bio-based green organic solvents (dihydro-L-glucanone, isosorbide dimethyl ether, soybean oil fatty acid methyl ester, lactate, and D-limonene), which can reduce adverse effects on the environment and human health, and realize the green preparation of polyurea-imide resin.
[0022] This invention provides a PEEK / PTFE self-lubricating fiber fabric composite material, comprising a PEEK / PTFE self-lubricating fiber fabric and a polyurea-imide resin laminated on the PEEK / PTFE self-lubricating fiber fabric. The polyurea-imide resin is cured from the polyurea-imide prepolymer described in the above technical solution. The PEEK / PTFE self-lubricating fiber fabric composite material provided by this invention exhibits excellent mechanical and tribological properties, demonstrating superior friction and wear resistance under light load and high speed conditions. As a lubricating layer, it can extend the stability and service life of moving parts. Attached Figure Description
[0023] Figure 1 ATR-FTIR spectra of the PURI-DMI precursor and PURI-DMI resin obtained in Example 1, and the PURI-DMAc precursor and PURI-DMAc resin obtained in Example 2.
[0024] Figure 2 Viscosity-temperature curves of the PURI-DMI precursor obtained in Example 1 and the PURI-DMAcprecursor obtained in Example 2 are shown.
[0025] Figure 3 The tensile strengths of PURI-DMI obtained in Example 1 and PURI-DMAc obtained in Example 2;
[0026] Figure 4 The bond strength of PURI-DMI obtained in Example 1 and PURI-DMAc obtained in Example 2;
[0027] Figure 5 The average coefficient of friction is the PURI-DMI obtained in Example 1 and the PURI-DMAc obtained in Example 2, which were tested for friction and wear performance at different rotational speeds.
[0028] Figure 6 The average wear rate (load 12.48 MPa) of the PURI-DMI obtained in Example 1 and the PURI-DMAc obtained in Example 2 under different rotation speeds was tested.
[0029] Figure 7 SEM images of the wear surfaces of different samples (scale bar is 500 μm). Figure 7In the image, (a) is a photograph of the wear surface of PURI-DMAc at 360 r / min, (b) is a photograph of the wear surface of PURI-DMI at 360 r / min, (c) is a photograph of the wear surface of PURI-DMAc at 600 r / min, (d) is a photograph of the wear surface of PURI-DMI at 600 r / min, (e) is a photograph of the wear surface of PURI-DMAc at 800 r / min, and (f) is a photograph of the wear surface of PURI-DMI at 800 r / min.
[0030] Figure 8 The friction coefficient and wear rate of the PURICOOH-DMAc composite material obtained in Comparative Example 1 under different working conditions are shown. Detailed Implementation
[0031] This invention provides a method for preparing a polyurea-imide prepolymer, comprising the following steps:
[0032] A polymerization reaction was carried out by mixing diamine, diisocyanate and organic solvent to obtain a small molecule with diamine-terminated urea group;
[0033] The diamine-terminated urea-containing small molecules are mixed with dianhydride and subjected to a polycondensation reaction to obtain the polyurea-imide prepolymer; at least one of the diamine and dianhydride contains fluorine, and the diisocyanate contains an alkyl chain.
[0034] Unless otherwise specified, all raw materials involved in this invention are commercially available products well known in the art.
[0035] This invention involves mixing diamine, diisocyanate, and organic solvent to perform a polymerization reaction, thereby obtaining a diamine-terminated urea-containing small molecule.
[0036] In this invention, at least one of the diamine and the subsequent dianhydride contains fluorine, preferably trifluoromethyl. In this invention, the diamine preferably comprises one or more of 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane, 2,2'-bis(trifluoromethyl)diaminobiphenyl, 2,2-bis(4-aminophenyl)hexafluoropropane, 2,2-bis(3-(3-aminobenzoylamino)-4-hydroxyphenyl)hexafluoropropane, 2-(4-aminophenyl)-5-aminobenzimidazole, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfone, and biphenyl diamine. In this invention, the diisocyanate contains an alkyl chain, which serves to provide soft segments for the molecular chain and increase the distance between the fluorinated groups. In this invention, the diisocyanate preferably includes one or more of hexamethylene diisocyanate, isophorone diisocyanate, trans-1,4-cyclohexyl diisocyanate, and lysine diisocyanate. In this invention, the molar ratio of the diisocyanate to the diamine is preferably (0.1–1.0):1.0, more preferably 0.5:1.0.
[0037] In this invention, the organic solvent preferably includes one or more of N,N-dimethylacetamide (DMAc), N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), N-methylpyrrolidone (NMP), dihydro-L-glucanone (Cyrene), isosorbide dimethyl ether (DMI), soybean oil fatty acid methyl ester, lactate, and D-limonene. N,N-dimethylacetamide, N,N-dimethylformamide, dimethyl sulfoxide, and N-methylpyrrolidone are low-toxicity organic solvents, while dihydro-L-glucanone, isosorbide dimethyl ether, soybean oil fatty acid methyl ester, lactate, and D-limonene are green, bio-based organic solvents. This invention focuses on the possibility of replacing standard highly toxic solvents with bio-based solvents without affecting the properties of the resulting resin. Currently, the use of environmentally friendly solvents is a desirable goal to reduce environmental impact and the adverse effects of classic solvents on human health; in particular, the use of green solvents can reduce safety hazards of fire and explosion, health hazards of acute and chronic toxicity, and environmental risks of air and water pollution. Furthermore, the use of bio-based solvents produced from renewable resources avoids the exploitation of fossil resources, thereby limiting carbon dioxide emissions into the environment. This invention does not have specific requirements regarding the amount of the organic solvent used, as long as it ensures the smooth dissolution of the raw materials and the successful progress of the reaction. In the embodiments of this invention, the preferred mass of the organic solvent is 2.5 to 4 times the total mass of the diamine and dianhydride.
[0038] In this invention, the polymerization reaction temperature is preferably 50-60°C, more preferably 55-60°C, and the time is preferably 5-9 hours, more preferably 6-8 hours; the polymerization reaction is preferably carried out under a protective atmosphere, preferably nitrogen.
[0039] In this invention, the preferred specific operation of the polymerization reaction is as follows:
[0040] The diamine is added to the organic solvent and stirred to dissolve, thus obtaining a diamine solution;
[0041] The diamine solution is heated to 50-60°C, and a protective atmosphere is introduced into the reaction vessel. Then, diisocyanate is slowly added dropwise to the diamine solution to carry out the polymerization reaction.
[0042] In this invention, the preferred dropping rate of the diisocyanate is 1 drop / min. When the diisocyanate is solid, it is preferable to dissolve it in a solvent before adding it dropwise. The polymerization reaction time is calculated from the point when the diisocyanate is completely added. In this invention, the slow dropping of the diisocyanate is used to avoid self-polymerization of the isocyanate. After the polymerization reaction is completed, a diamine-terminated urea-containing small molecule is obtained, which requires no post-treatment and can be directly proceeded to the next reaction.
[0043] After obtaining the diamine-terminated urea-containing small molecule, the present invention mixes the diamine-terminated urea-containing small molecule with dianhydride and carries out a polycondensation reaction to obtain the polyurea-imide prepolymer.
[0044] In this invention, the dianhydride preferably includes one or more of pyromellitic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 3,3',4,4'-benzophenone tetracarboxylic dianhydride, 3,3',4,4'-diphenyl ether tetracarboxylic dianhydride, and hexafluoroisopropylphthalic anhydride; the molar ratio of the dianhydride to the diamine is preferably (0.1-1.0):1.0, more preferably 0.5:1.0. In this invention, the diisocyanate provides the soft segment of the molecular chain, and the diamine and dianhydride provide the hard segment.
[0045] In this invention, the temperature of the polycondensation reaction is preferably 0-5°C, and the time is preferably 10-14 hours, more preferably 12-13 hours; the polycondensation reaction is preferably carried out under a protective atmosphere, preferably nitrogen.
[0046] In this invention, the preferred specific operation of the polycondensation reaction is as follows:
[0047] The dianhydride is dissolved in a solvent to obtain a dianhydride solution; the solvent is the same as the organic solvent described in the above technical solution.
[0048] The diamine-terminated urea-containing small molecule is cooled to 0-5°C, and the dianhydride solution is added dropwise under stirring and a protective atmosphere to carry out a polycondensation reaction.
[0049] In this invention, the dropping rate of the dianhydride solution is preferably 1 mL·min. -1 The time for the polycondensation reaction is calculated from the point when the dianhydride solution is completely added. After the polycondensation reaction, no post-processing is required to obtain the polyurea-imide prepolymer.
[0050] Polyimide resins possess advantages such as high temperature resistance and strong mechanical properties, but their adhesive properties are inferior to those of polyurethane and phenolic resins. While polyurethane has excellent adhesive properties, its high temperature resistance is poor. Inspired by the distribution of soft and hard segments in dragonfly wings, this invention provides a method for synthesizing polyurea-imide prepolymers. This method introduces diisocyanate as the soft segment into the resin, while fluorinated diamines and dianhydrides act as hard segments. This not only avoids the weak or non-existent adhesive properties caused by fluorine but also constructs a microphase separation structure, thereby enhancing the resin's mechanical properties, thermal stability, and electrical conductivity. This invention enables the preparation of fluorinated, high-temperature resistant polyurea-imide prepolymers with excellent adhesive properties under normal pressure.
[0051] This invention provides a polyurea-imide prepolymer prepared by the method described above. In this invention, the polyurea-imide prepolymer contains urea groups and amide bonds. The polyurea-imide prepolymer provided by this invention exhibits both excellent adhesion and high-temperature resistance.
[0052] This invention provides a PEEK / PTFE self-lubricating fiber fabric composite material, comprising a PEEK / PTFE self-lubricating fiber fabric and a polyurea-imide resin composited on the PEEK / PTFE self-lubricating fiber fabric, wherein the polyurea-imide resin is cured from the polyurea-imide prepolymer described in the above technical solution.
[0053] This invention does not impose any special requirements on the PEEK / PTFE self-lubricating fiber fabric; it can be prepared using commercially available products or methods well-known to those skilled in the art. In this embodiment, the PEEK / PTFE self-lubricating fiber fabric is woven in a twill weave, wherein the areal density ratio of PTFE fibers to PEEK fibers is 2:1.
[0054] This invention provides a method for preparing the PEEK / PTFE self-lubricating fiber fabric composite material described in the above technical solution, comprising the following steps:
[0055] PEEK / PTFE self-lubricating fiber fabric is impregnated in the polyurea-imide prepolymer to obtain PEEK / PTFE self-lubricating fiber fabric prepreg.
[0056] The PEEK / PTFE self-lubricating fiber fabric prepreg is bonded to the surface of the substrate and cured to obtain the PEEK / PTFE self-lubricating fiber fabric composite material.
[0057] This invention involves impregnating a PEEK / PTFE self-lubricating fiber fabric in a polyurea-imide prepolymer to obtain a PEEK / PTFE self-lubricating fiber fabric prepreg. In this invention, the viscosity of the polyurea-imide prepolymer is preferably 0.2–0.8 Pa·s. When the viscosity of the polyurea-imide prepolymer is high, it is preferable to dilute the polyurea-imide prepolymer with a solvent to a viscosity of 0.2–0.8 Pa·s before impregnation; the solvent is preferably the same as the organic solvent described in the above technical solution. In this invention, the impregnation is preferably repeated. After each impregnation, the impregnated fabric is preferably dried in an oven at 60–70°C (preferably 65–70°C) before the next impregnation. The number of impregnations is based on the PEEK / PTFE self-lubricating fiber fabric comprising 65–70% of the mass of the PEEK / PTFE self-lubricating fiber fabric in the prepreg.
[0058] After obtaining the PEEK / PTFE self-lubricating fiber fabric prepreg, the present invention adheres the PEEK / PTFE self-lubricating fiber fabric prepreg to the surface of a substrate and cures it to obtain the PEEK / PTFE self-lubricating fiber fabric composite material. In this invention, the adhesive used for bonding is the polyurea-imide prepolymer (without additional dilution), that is, the substrate and the self-lubricating fiber fabric composite material are chemically bonded through the polyurea-imide prepolymer (as an adhesive). In this invention, the substrate preferably includes a steel substrate or a titanium alloy substrate, and the steel substrate preferably includes a bearing steel substrate.
[0059] In this invention, the curing process preferably includes: heating from room temperature to 80°C at a heating rate of 3–5°C / min and holding for 2 hours; then heating to 100°C at a heating rate of 3–5°C / min and holding for 1 hour; then heating to 150°C at a heating rate of 3–5°C / min and holding for 1 hour; then heating to 180°C at a heating rate of 2–5°C / min and holding for 1 hour, and finally naturally cooling to room temperature; the curing is carried out under normal pressure. This invention employs gradient temperature curing to ensure that the material can fully react and cure at different temperature ranges, while avoiding internal stress and defects caused by excessively rapid heating, ultimately obtaining a polyimide material with stable performance. This invention controls the curing temperature of the final stage at 180°C, which can avoid molecular chain breakage (if the temperature is too high, the urea groups will break and recombine), while satisfying the imidization of polyimide. Furthermore, while existing fluorinated polyimide resins can provide high-temperature resistance, their molding process requires hot pressing, which is not suitable for the molding process of existing self-lubricating fabric curved parts for bearings. In contrast, the curing described in this invention can be carried out under normal pressure.
[0060] This invention provides the application of the PEEK / PTFE self-lubricating fiber fabric composite material described in the above technical solutions or the PEEK / PTFE self-lubricating fiber fabric composite material prepared by the above preparation methods in the field of lubrication. The PEEK / PTFE self-lubricating fiber fabric composite material provided by this invention possesses excellent adhesive tensile and tribological properties, exhibiting superior friction and wear performance under light load and high speed conditions. It can extend the stability and service life of moving parts (such as bearings) when the fiber fabric self-lubricating composite material is used as a lubrication layer.
[0061] To further illustrate the present invention, the following detailed description, in conjunction with examples, of the polyurea-imide prepolymer and the PEEK / PTFE self-lubricating fiber fabric composite material provided by the present invention, as well as their preparation and application, should not be construed as limiting the scope of protection of the present invention.
[0062] In all embodiments and comparative examples, the PEEK / PTFE self-lubricating fiber fabric is woven in a twill weave, wherein the areal density ratio of PTFE fiber to PEEK fiber is 2:1.
[0063] Example 1
[0064] First, 5.5474 g (0.0107 mol, 2 equivalents) of 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane (HFBAPP) was dissolved in 20 mL of isosorbide dimethyl ether (DMI) under stirring. The mixture was heated to 60 °C in a water bath, and high-purity nitrogen was introduced into the reaction vessel. Then, 0.8999 g (0.00535 mol, 1 equivalent) of hexamethylene diisocyanate was added dropwise to the reaction vessel. After reacting for 8 hours, the reaction vessel containing the reactants was transferred to an ice-water bath at 0–5 °C, again under a high-purity nitrogen atmosphere. Next, 1.7239 g (0.00535 mol, 1 equivalent) of 3,3',4,4'-benzophenone tetracarboxylic dianhydride (BTDA) was dissolved in 15 mL of DMI and reacted at a rate of 1 mL·min⁻¹. -1 The polymer was added dropwise to the above reactants at a rate of [missing information]. After reacting for 12 hours, a polyurea-imide prepolymer (PURI-DMI precursor) was obtained.
[0065] The PURI-DMI precursor was diluted with DMI to a viscosity of 0.5 Pa·s. The PEEK / PFTE blended fabric was then repeatedly impregnated in the diluted PURI-DMI precursor solution, and after each impregnation, it was dried in an oven at 65°C before the next impregnation. This process continued until the PEEK / PFTE blended fabric comprised 65–70% of the total mass, yielding the PEEK / PTFE prepreg.
[0066] PEEK / PTFE prepreg was bonded to the surface of 45# steel using PURI-DMI precursor. The sample was then placed in a muffle furnace for curing. The curing procedure was as follows: heat to 80°C in 20 minutes and hold for 2 hours; then heat to 100°C in 5 minutes and hold for 1 hour; subsequently heat to 150°C and 180°C in 15 minutes, holding for 1 hour at each temperature; finally, the sample was allowed to cool naturally to room temperature in the muffle furnace to obtain a PEEK / PTFE self-lubricating fiber fabric composite material, denoted as PURI-DMI. PURI-DMI precursor was then drop-coated onto a glass slide and cured at the same curing temperature. The film was then separated from the glass slide to obtain polyurea-imide resin, denoted as PURI-DMI resin.
[0067] Example 2
[0068] First, 5.5474 g (0.0107 mol, 2 equivalents) of 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane (HFBAPP) was dissolved in 20 mL of N,N-dimethylacetamide (DMAc) under stirring. The mixture was heated to 60 °C in a water bath, and high-purity nitrogen was introduced into the reaction vessel. Then, 0.8999 g (0.00535 mol, 1 equivalent) of hexamethylene diisocyanate was added dropwise to the reaction vessel. After reacting for 8 hours, the reaction vessel containing the reactants was transferred to an ice-water bath at 0–5 °C, again under a high-purity nitrogen atmosphere. Next, 1.7239 g (0.00535 mol, 1 equivalent) of BTDA was dissolved in 15 mL of DMAc and reacted at a rate of 1 mL·min⁻¹. -1 The polymer was added dropwise to the above reactants at a rate of [missing information]. After reacting for 12 hours, a polyurea-imide prepolymer (PURI-DMAcprecursor) was obtained.
[0069] The PEEK / PFTE blended fabric is repeatedly impregnated with PURI-DMAc precursor, and after each impregnation, it is dried in an oven at 65°C before the next impregnation. This process is repeated until the PEEK / PFTE blended fabric accounts for 65-70% of the total mass, thus obtaining the PEEK / PTFE prepreg.
[0070] PEEK / PTFE prepreg was adhered to the surface of 45# steel, and the sample was placed in a muffle furnace for curing. The curing procedure was as follows: heat to 80℃ in 20 minutes and hold for 2 hours; then heat to 100℃ in 5 minutes and hold for 1 hour; subsequently heat to 150℃ and 180℃ in 15 minutes, holding for 1 hour at each temperature; finally, the sample was allowed to cool naturally to room temperature in the muffle furnace to obtain a PEEK / PTFE self-lubricating fiber fabric composite material, denoted as PURI-DMAc. The PURI-DMAc precursor was drop-coated onto a glass slide and cured at the same curing temperature as described above. The film was then separated from the glass slide to obtain polyurea-imide resin, denoted as PURI-DMAc resin.
[0071] Comparative Example 1
[0072] First, 4.1606 g (0.008025 mol, 3 / 2 equivalent) of 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane (HFBAPP) was dissolved in 20 mL of N,N-dimethylacetamide (DMAc) under stirring. The mixture was heated to 60 °C in a water bath, and high-purity nitrogen was introduced into the reaction vessel. Then, 0.4070 g (0.002675 mol, 1 / 2 equivalent) of 3,5-diaminobenzoic acid (DABA) was added to the reaction vessel until the DABA was completely dissolved. Subsequently, 0.8999 g (0.00535 mol, 1 equivalent) of hexamethylene diisocyanate was added dropwise to the reaction vessel. After reacting for 8 hours, the reaction vessel containing the reactants was transferred to an ice-water bath at 0–5 °C, again under a high-purity nitrogen atmosphere. Then, 1.7239 g (0.00535 mol, 1 equivalent) of BTDA was dissolved in 15 mL of DMAc and discharged at a rate of 1 mL·min⁻¹. -1 The solution was added dropwise to the above reactants at a rate equal to [amount]. After reacting for 12 hours, a polyurea-imide prepolymer (PURICOOH-DMAcprecursor) was obtained.
[0073] The PEEK / PFTE blended fabric is repeatedly impregnated with PURICOOH-DMAc precursor, and after each impregnation, it is dried in an oven at 65°C before the next impregnation. This process is repeated until the PEEK / PFTE blended fabric accounts for 65-70% of the total mass, thus obtaining the PEEK / PTFE prepreg.
[0074] PEEK / PTFE prepreg was adhered to the surface of 45# steel, and the sample was placed in a muffle furnace for curing. The curing procedure was as follows: heat to 80℃ in 20 minutes and hold for 2 hours; then heat to 100℃ in 5 minutes and hold for 1 hour; subsequently heat to 150℃ and 180℃ in 15 minutes, holding for 1 hour at each temperature; finally, the sample was allowed to cool naturally to room temperature in the muffle furnace to obtain a PEEK / PTFE self-lubricating fiber fabric composite material, denoted as PURICOOH-DMAc. The PURICOOH-DMAc precursor was drop-coated onto a glass slide and cured at the same curing temperature as described above. The film was then separated from the glass slide to obtain polyurea-imide resin, denoted as PURICOOH-DMAc resin.
[0075] Example 3
[0076] First, 3.4265 g (0.0107 mol, 2 equivalents) of 2,2'-bis(trifluoromethyl)diaminobiphenyl was dissolved in 20 mL of dihydro-L-glucosamine (Cyrene) under stirring. The mixture was heated to 60 °C in a water bath, and high-purity nitrogen was introduced into the reaction vessel. Then, 0.8999 g (0.00535 mol, 1 equivalent) of hexamethylene diisocyanate was added dropwise to the reaction vessel. After reacting for 8 hours, the reaction vessel containing the reactants was transferred to an ice-water bath at 0–5 °C, again under a high-purity nitrogen atmosphere. Next, 1.7239 g (0.00535 mol, 1 equivalent) of BTDA was dissolved in 15 mL of Cyrene and reacted at a rate of 1 mL·min⁻¹. -1 The polymer was added dropwise to the above reactants at a rate of [missing information]. After reacting for 12 hours, a polyurea-imide prepolymer (PURI-Cyrene precursor) was obtained.
[0077] The PEEK / PFTE blended fabric is repeatedly impregnated in a PURI-Cyrene precursor. After each impregnation, it is dried in an oven at 65°C before the next impregnation. This process is repeated until the PEEK / PFTE blended fabric accounts for 65-70% of the total mass, thus obtaining the PEEK / PTFE prepreg.
[0078] PEEK / PTFE prepreg was adhered to the surface of 45# steel, and the sample was placed in a muffle furnace for curing. The curing procedure was as follows: heat to 80℃ in 20 minutes and hold for 2 hours; then heat to 100℃ in 5 minutes and hold for 1 hour; subsequently heat to 150℃ and 180℃ in 15 minutes, holding for 1 hour at each temperature; finally, the sample was allowed to cool naturally to room temperature in the muffle furnace to obtain a PEEK / PTFE self-lubricating fiber fabric composite material, denoted as PURI-Cyrene. PURI-Cyrene precursor was drop-coated onto a glass slide and cured at the same curing temperature as described above. The film was then separated from the glass slide to obtain polyurea-imide resin, denoted as PURI-Cyrene resin.
[0079] Example 4
[0080] First, 3.5766 g (0.0107 mol, 2 equivalents) of 2,2-bis(4-aminophenyl)hexafluoropropane was dissolved in 20 mL of isosorbide dimethyl ether (DMI) under stirring. The mixture was heated to 60 °C in a water bath, and high-purity nitrogen was introduced into the reaction vessel. Then, 0.8999 g (0.00535 mol, 1 equivalent) of hexamethylene diisocyanate was added dropwise to the reaction vessel. After reacting for 8 hours, the reaction vessel containing the reactants was transferred to an ice-water bath at 0–5 °C, again under a high-purity nitrogen atmosphere. Next, 1.7239 g (0.00535 mol, 1 equivalent) of BTDA was dissolved in 15 mL of DMI and reacted at a rate of 1 mL·min⁻¹. -1 The reagent was added dropwise to the above reactants at a rate of [missing information]. After reacting for 12 hours, a polyurea-imide prepolymer (PURI-DMI-1 precursor) was obtained.
[0081] The PEEK / PFTE blended fabric is repeatedly impregnated in the PURI-DMI-1 precursor. After each impregnation, it is dried in an oven at 65°C before the next impregnation. This process continues until the PEEK / PFTE blended fabric accounts for 65-70% of the total mass, thus obtaining the PEEK / PTFE prepreg.
[0082] PEEK / PTFE prepreg was adhered to the surface of 45# steel, and the sample was placed in a muffle furnace for curing. The curing procedure was as follows: heat to 80℃ in 20 minutes and hold for 2 hours; then heat to 100℃ in 5 minutes and hold for 1 hour; then heat to 150℃ and 180℃ in 15 minutes, holding for 1 hour at each temperature; finally, the sample was allowed to cool naturally to room temperature in the muffle furnace to obtain a PEEK / PTFE self-lubricating fiber fabric composite material, denoted as PURI-DMI-1. PURI-DMI-1 precursor was drop-coated onto a glass slide and cured at the same curing temperature as described above. The film was then separated from the glass slide to obtain polyurea-imide resin, denoted as PURI-DMI-1 resin.
[0083] Performance testing and structural characterization
[0084] Figure 1 The ATR-FTIR spectra of the PURI-DMI precursor and PURI-DMI resin obtained in Example 1, and the PURI-DMAc precursor and PURI-DMAc resin obtained in Example 2, are shown at 3370 cm⁻¹. -1 The nearby peaks are caused by the -NH- vibration. The peak at 2930 cm⁻¹ is... -1 and 2850cm -1 The peak is due to the asymmetric and symmetric vibrations of CH in -CH2-. (1719 cm⁻¹)-1 and 1783cm -1 The peak at that point is due to the C=O vibration. Meanwhile, the vibration originating from the trifluoromethyl (-CF3) group in HFBAPP occurs between 1200 and 1324 cm⁻¹. -1 A peak appears at 3500–2730 cm⁻¹. Compared to PURI-DMI resin and PURI-DMAc resin, the spectra of PURI-DMI and PURI-DMAc precursors show peaks at 3500–2730 cm⁻¹. -1 There is a relatively broad scattering peak at this point, which is due to the OH group in the precursor. However, after thermal imidization, an imine ring is formed, the -OH group is removed, and the scattering peak disappears in PURI-DMIresin and PURI-DMAc resin.
[0085] The viscosity-temperature profiles of PURI-DMI precursor and PURI-DMAcprecursor were tested using an Anton Paar MCR 302 rheometer from Austria. For hand lay-up molding, the resin viscosity is generally best controlled between 0.2 Pa·s and 0.8 Pa·s. This viscosity range helps ensure sufficient resin wetting of the fibers while avoiding resin runoff caused by excessively low viscosity. Figure 2 The image shows the viscosity-temperature curves of the PURI-DMI precursor and the PURI-DMAc precursor. Figure 2 It can be seen that PURI-DMI precursor has a high viscosity, reaching 9.596 Pa·s at 25℃, which is far higher than the ideal viscosity. Therefore, it needs to be diluted with DMI solvent to bring its viscosity within the ideal range. In contrast, PURI-DMAc precursor has a viscosity of 0.39 Pa·s at 25℃, and can therefore be used directly.
[0086] The mechanical properties of PEEK / PTFE self-lubricating fiber fabric composites were evaluated using a general-purpose testing machine. Each sample measured 12cm × 2cm, and the testing machine performed tensile tests on the fabric composites at a speed of 20mm / min. Five measurements were taken for each specimen, and the average tensile strength was calculated from three intermediate values. The results are shown below. Figure 3The bond strength of the fabric composite was investigated using an electronic fabric strength tester (YG026D) at a crosshead speed of 20 mm / min. The impregnated fabric was cut to given dimensions (12 cm long, 2 cm wide). The test samples were then fixed onto AISI-1045 steel plates (60 mm long, 20 mm wide, with an adhesive length of 45 mm) using the corresponding prepolymer and cured. Five measurements were performed on each sample, and the average bond strength was calculated using three intermediate values. The results are shown below. Figure 4 As shown. Figure 3 and Figure 4 It can be seen that the tensile properties of PURI-DMI (188.20±3.57MPa) are slightly higher than those of PURI-DMAc (178.49±4.74MPa), while the peel strength of PURI-DMI (1.23±0.32N / mm) is significantly higher than that of PURI-DMAc (0.82±0.09N / mm). In summary, PURI-DMI possesses superior mechanical properties.
[0087] The tribological properties of PURI-DMAc or PURI-DMI composite materials were tested using the Xuanwu No. 3 tribological testing machine (contact method: pin-disc, rotation speeds: 360 r / min, 600 r / min, 800 r / min, load: 12.48 MPa, test time: 120 min). Figure 5 The average friction coefficient of the composite material is shown in Table 1. Figure 6 This is the average wear rate, and the corresponding data is shown in Table 2.
[0088] Table 1. Friction coefficients of PURI-DMAc and PURI-DMI composite materials.
[0089]
[0090] Table 2 Wear rates of PURI-DMAc and PURI-DMI composite materials
[0091]
[0092] Depend on Figures 5-6 As can be seen from Tables 1 and 2, under the experimental conditions, PURI-DMI exhibits a lower coefficient of friction and wear rate.
[0093] Figure 7 These are SEM images of the wear surfaces of different samples. Figure 7(a) shows the wear surface photograph of PURI-DMAc at 360 r / min, (b) shows the wear surface photograph of PURI-DMI at 360 r / min, (c) and (d) show the wear surface photographs of PURI-DMAc and PURI-DMI at 600 r / min, respectively, and (e) and (f) show the wear surface photographs of PURI-DMAc and PURI-DMI at 800 r / min, respectively. PURI-DMAc shows the most severe wear at 600 r / min, with a large number of fibers broken and pulled out. However, when the operating conditions become more severe, i.e., the speed is increased to 800 r / min, the wear of both PURI-DMAc and PURI-DMI is significantly reduced. This is because the frictional heat increases with the increase in speed. Polyurea-imide resin is a modified version of polyimide resin, and polyimide resin has better high-temperature tribological properties than room-temperature properties within a certain range. Therefore, the wear resistance of PURI-DMAc and PURI-DMI also improves with increasing speed. In other words, both PURI-DMAc and PURI-DMI exhibit ideal tribological properties at high speeds; while at medium or low speeds, PURI-DMI also exhibits ideal tribological properties (low friction and low wear), thus PURI-DMI has superior mechanical and tribological properties.
[0094] Figure 8 To illustrate the friction coefficient and wear rate of the PURICOOH-DMAc composite material prepared in Comparative Example 1 under different working conditions, the friction and wear properties of the PURICOOH-DMAc composite material were tested using the Xuanwu No. 3 tribometer (pin-disc contact method, rotation speeds of 360 r / min and 600 r / min, and test time of 120 min). The corresponding values are shown in Table 3.
[0095] Table 3 shows the friction coefficient and wear rate of the PURICOOH-DMAc composite material obtained in Comparative Example 1.
[0096]
[0097] The introduction of DABA in PURICOOH-DMAc resin reduces the content of -CF3 groups, and compared to HFBAPP, the DABA benzene ring content is lower, resulting in a lower hard segment content. Therefore, PURICOOH-DMAc lacks a microphase-separated structure. Compared to PURI-DMI and PURI-DMAc, which have microphase-separated structures, PURICOOH-DMAc exhibits a lower coefficient of friction but a higher wear rate at 12.48 MPa and 600 r / min. This is because the PTFE fibers within the fabric act as lubricants, leading to a lower coefficient of friction. PURICOOH-DMAc demonstrates poor tribological properties. Therefore, resins with a microphase-separated structure inspired by dragonfly wing designs can possess better tribological properties.
[0098] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.
Claims
1. A method for preparing a polyurea-imide prepolymer, characterized in that, Includes the following steps: A polymerization reaction was carried out by mixing diamine, diisocyanate and organic solvent to obtain a small molecule with diamine-terminated urea group; The diamine-terminated urea-containing small molecules are mixed with dianhydride and subjected to a polycondensation reaction to obtain the polyurea-imide prepolymer; at least one of the diamine and dianhydride contains fluorine, and the diisocyanate contains an alkyl chain; The diamine is one or more of 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane, 2,2'-bis(trifluoromethyl)diaminobiphenyl, 2,2-bis(4-aminophenyl)hexafluoropropane, 2,2-bis(3-(3-aminobenzoylamino)-4-hydroxyphenyl)hexafluoropropane, 2-(4-aminophenyl)-5-aminobenzimidazole, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfone, and biphenyl diamine. The diisocyanate is one or more selected from hexamethylene diisocyanate, isophorone diisocyanate, trans-1,4-cyclohexyl diisocyanate, and lysine diisocyanate; the molar ratio of the diisocyanate to the diamine is (0.1~1.0):1.0; The dianhydride is one or more selected from pyromellitic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 3,3',4,4'-benzophenone tetracarboxylic dianhydride, 3,3',4,4'-diphenyl ether tetracarboxylic dianhydride, and hexafluoroisopropylphthalic anhydride; the molar ratio of the dianhydride to the diamine is (0.1~1.0):1.0; The organic solvent is one or more of dihydro-L-glucanone, isosorbide dimethyl ether, soybean oil fatty acid methyl ester, lactate and D-limonene; The polymerization reaction is carried out at a temperature of 50-60°C for 5-9 hours; the polycondensation reaction is carried out at a temperature of 0-5°C for 10-14 hours; both the polymerization and polycondensation reactions are carried out under a protective atmosphere.
2. The polyurea-imide prepolymer prepared by the method of claim 1.
3. A PEEK / PTFE self-lubricating fiber fabric composite material, characterized in that, It includes a PEEK / PTFE self-lubricating fiber fabric and a polyurea-imide resin composited on the PEEK / PTFE self-lubricating fiber fabric, wherein the polyurea-imide resin is cured from the polyurea-imide prepolymer of claim 2.
4. The method for preparing the PEEK / PTFE self-lubricating fiber fabric composite material according to claim 3, characterized in that, Includes the following steps: PEEK / PTFE self-lubricating fiber fabric is impregnated in the polyurea-imide prepolymer to obtain PEEK / PTFE self-lubricating fiber fabric prepreg. The PEEK / PTFE self-lubricating fiber fabric prepreg is bonded to the surface of the substrate and cured to obtain the PEEK / PTFE self-lubricating fiber fabric composite material.
5. The application of the PEEK / PTFE self-lubricating fiber fabric composite material according to claim 3 or the PEEK / PTFE self-lubricating fiber fabric composite material prepared by the preparation method according to claim 4 in the field of lubrication.