Wear-resistant PEEK composite material and application of wear-resistant PEEK composite material in reversing valve for air bag pump

Abstract

The invention provides a wear-resistant PEEK composite material and application of the wear-resistant PEEK composite material in a reversing valve for an air bag pump, and relates to the technical field of air bag pumps. The wear-resistant PEEK composite material comprises the following raw materials in parts by weight: 100 parts of PEEK, 2-5 parts of aramid fibers and 5-10 parts of siloxane modified carbon fibers. The wear-resistant PEEK composite material takes PEEK as a base material, the aramid fibers and the siloxane modified carbon fibers are added, and all the components are matched with one another, so that the obtained wear-resistant PEEK composite material has excellent impact resistance, wear resistance and heat resistance, is simple in processing technology and is suitable for large-scale popularization.

Description

Technical Field

[0001] The present invention relates to the technical field of bellows pumps, and in particular to a wear-resistant PEEK composite material and an application thereof in a reversing valve for a bellows pump. Background Art

[0002] A bellows pump uses a variable-volume bellows to alternately increase and decrease the working volume within the pump cylinder to transport special liquids. It is particularly widely used in the semiconductor and electronics industries, often transporting highly corrosive special liquids such as strong acids and alkalis. The reversing valve is a key component of the bellows pump, primarily used to connect, disconnect, and reverse the flow of hydraulic oil. The reversing valve relies primarily on the relative motion between the valve core and valve body for control. Frequent friction and prolonged use of the valve core can lead to severe wear, and frequent replacement increases production costs. This requires the valve core structure to possess high wear resistance and mechanical strength to increase service life, reduce replacement frequency, and lower costs.

[0003] Polyetheretherketone (PEEK) is a semicrystalline, aromatic thermoplastic specialty engineering plastic with advantages such as high temperature resistance, high elasticity, high modulus, excellent dimensional stability, corrosion resistance, and good wear resistance. Currently, pure PEEK is used in valve bodies, valve cores, and valve sleeves of directional control valves. Despite its excellent wear resistance, PEEK also suffers from significant wear losses due to friction. Furthermore, its impact strength needs to be improved, making it incapable of withstanding the prolonged operation of bladder pump directional control valves. Adding a certain amount of reinforcing materials such as glass fiber, carbon fiber, graphene, and carbon nanotubes is an important method for improving the material's frictional properties. However, conventional reinforcing materials have poor compatibility with PEEK, affecting the overall performance of the composite. While surface-treated reinforcing materials improve compatibility with PEEK, they do not simultaneously improve the wear and impact resistance of PEEK. Therefore, there is a need for a material with good wear resistance that can withstand the operating pressures of bladder pumps for a long time. Summary of the Invention

[0004] The purpose of the present invention is to address the deficiencies of the prior art and provide a wear-resistant PEEK composite material and its application in a reversing valve for a bellows pump.

[0005] To achieve the above object, the technical solution adopted by the present invention is as follows: In one aspect, a wear-resistant PEEK composite material comprises the following raw materials in parts by weight: 100 parts of PEEK, 2 to 5 parts of aramid fiber, and 5 to 10 parts of siloxane-modified carbon fiber.

[0006] Preferably, the wear-resistant PEEK composite material comprises the following raw materials in parts by weight: 100 parts of PEEK, 3 parts of aramid fiber, and 7 parts of silicone-modified carbon fiber.

[0007] Furthermore, the diameter of the siloxane-modified carbon fiber is 1 to 5 μm, and the length is 0.5 to 5 mm.

[0008] Furthermore, the siloxane-modified carbon fiber is obtained by impregnating and modifying carbon fiber with amino-terminated polydimethylsiloxane.

[0009] Furthermore, the amino-terminated polydimethylsiloxane has a weight average molecular weight of 5,000 to 20,000 and an amino group content of 0.1 to 0.5 mmol / g.

[0010] Specifically, the siloxane-modified carbon fiber is prepared by the following method: (1) Treating carbon fibers with an oxidant at 100-120°C for 4-6 hours to obtain surface-oxidized carbon fibers; the oxidant is selected from nitric acid, acidic potassium dichromate, sodium hypochlorite, hydrogen peroxide or potassium persulfate. The surface oxidation process is to place the carbon fibers in an aqueous solution of the oxidant for a period of time, then take them out and wash away the residual oxidant on the surface with water. The mass fraction of the aqueous solution is generally greater than 10%, such as a 30% nitric acid solution. (2) Adding amino-terminated polydimethylsiloxane to acetone and adding surface oxidized carbon fibers, the mass ratio of amino-terminated polydimethylsiloxane to surface oxidized carbon fibers is (2-3):10, preferably 2.4:10; immersing treatment is performed at room temperature for 6-8 hours, and washing and drying are performed after treatment to obtain the product.

[0011] Furthermore, the aramid fiber has a diameter of 5 to 12 μm and a length of 5 to 10 mm.

[0012] In a further embodiment, the aramid fiber is plasma-treated aramid fiber. During the plasma treatment, the treatment medium is air, oxygen, nitrogen or argon, the gas flow rate is 10 cm / min to 3100 cm / min, the plasma generating power is 50W to 300W, and the treatment time is 50s to 300s.

[0013] Furthermore, the PEEK contains 20-30% carboxylated PEEK, that is, the mass ratio of PEEK to carboxylated PEEK is (70-80):(20-30), preferably 26% carboxylated PEEK; the degree of carboxylation of the carboxylated PEEK is 18-25%, preferably 20%; the carboxylated PEEK is prepared by the following method: Mix 4,4-difluorobenzophenone, hydroquinone, 3,5-dihydroxybenzoic acid, alkali metal carbonate and toluene, carry out polymerization reaction under nitrogen protection, pour into water after the reaction, add hydrochloric acid to acidify, wash and dry to obtain the product.

[0014] The present application prepares carboxylated PEEK by reacting three monomers, 4,4-difluorobenzophenone, hydroquinone, and dihydroxybenzoic acid. By controlling the molar ratio of dihydroxybenzoic acid in the three monomers to 18-25%, a PEEK with a carboxylation degree of 18-25% is obtained, which has excellent heat resistance. When combined with PEEK as a base material for wear-resistant materials, and in combination with other components, the wear-resistant materials can be given good heat resistance, wear resistance, and impact resistance. In the above-mentioned carboxylated PEEK preparation process, in addition to the molar ratio of dihydroxybenzoic acid needing to be controlled in the range of 18-25%, the molar ratios of 4,4-difluorobenzophenone and hydroquinone are preferably 50-70% and 12-25%, respectively; the alkali metal carbonate is preferably potassium carbonate and / or sodium carbonate, and its amount is generally not less than 20% of the total mass of the three monomers, preferably 20-30%; the amount of solvent toluene is adjusted according to the amount of traditional Chinese medicine, and it is sufficient to dissolve the monomers, and excess toluene is usually used. The polymerization reaction is carried out at a temperature of 200-250° C., preferably prepolymerization is carried out at 200-210° C. for 1-2 hours, and then the temperature is raised to 240-250° C. for polymerization for 1-2 hours. The amount of hydrochloric acid and the acidification time are adjusted according to the required degree of carboxylation during the acidification process. The temperature is raised to 150-160° C. and kept warm for 1-2 hours, then raised to 200-210° C. for prepolymerization for 1-1.5 hours, while the remaining toluene is evaporated, and then the temperature is raised to 240-250° C. and kept warm for 1-2 hours for polymerization. After the reaction is completed, the mixture is poured into water, hydrochloric acid is added and acidified for 6 hours, and the mixture is washed with ethanol and water respectively, and dried to obtain the product.

[0015] On the other hand, the preparation method of the above-mentioned wear-resistant PEEK composite material comprises the following steps: After PEEK, aramid fiber and silicone modified carbon fiber are fully mixed, they are placed in a mold for hot pressing at a temperature of 390-400°C and a pressure of 10-15 MPa; and then annealing is performed to obtain the product.

[0016] Furthermore, the annealing treatment temperature is 250-260° C., and the time is 1-2 hours.

[0017] On the other hand, the wear-resistant PEEK composite material is used in the preparation of a reversing valve for a bellows pump.

[0018] Furthermore, the application includes using the wear-resistant PEEK composite material to prepare at least one of a valve body, a valve sleeve, and a valve core in a reversing valve for a bellows pump.

[0019] Compared with the prior art, this application has the following beneficial effects: 1. Aramid fiber and amino-terminated polydimethylsiloxane-modified carbon fiber are added to the wear-resistant PEEK composite material of the present application and compounded with PEEK, thereby improving the impact resistance and wear resistance of the PEEK material. The processing technology is simple and suitable for large-scale promotion.

[0020] 2. The wear-resistant PEEK composite material of the present application adds terminal amino-modified polydimethylsiloxane modified carbon fiber. Compared with carbon fiber, the carbon fiber modified by terminal amino-modified polydimethylsiloxane can better achieve dispersion and bonding in PEEK material, improve interface compatibility, reduce the generation of interface defects, improve friction resistance, relieve interface stress concentration under external force, and improve impact resistance; in addition, the terminal amino-modified polydimethylsiloxane structure can also play a certain protective role for PEEK at high temperature, thereby improving high temperature resistance.

[0021] 3. Aramid fiber is added to the wear-resistant PEEK composite material of the present application. Aramid fiber has high tensile strength, good impact performance, high elastic modulus, and good thermal stability. Adding a certain amount of aramid fiber helps to improve the impact resistance and wear resistance of the material; however, the surface inertness of aramid fiber is strong, its compatibility with PEEK is poor, and it is easy to agglomerate in PEEK material. The present application introduces active groups by plasma treatment on the aramid surface, thereby enhancing the interface bonding with PEEK, thereby better improving the impact resistance and wear resistance of the material.

[0022] 4. The PEEK in this application contains a certain amount of carboxylated PEEK. The presence of carboxylated PEEK can react with aramid fibers and carbon fibers to form a stable chemical connection, thereby enhancing the interfacial bonding strength between the individual components, while retaining the high temperature resistance, corrosion resistance and other properties of the PEEK material.

[0023] 5. The wear-resistant PEEK composite material of this application has achieved effective improvement in wear resistance and impact resistance through the combined effect of the above aspects, with the friction coefficient reduced to below 0.1 and the impact strength reaching up to 40kJ / m 2 above. DETAILED DESCRIPTION

[0024] The following non-limiting examples are provided to enable those skilled in the art to more fully understand the present invention, but are not intended to limit the present invention in any way. The following is merely an illustrative description of the scope of the present invention, and those skilled in the art may make various changes and modifications to the present invention based on the disclosed content, which should also fall within the scope of the present invention.

[0025] Unless otherwise specified, the various chemical reagents used in the embodiments of the present invention are obtained through conventional commercial channels. Among them, amino-terminated polydimethylsiloxane can be purchased directly or prepared by a preparation method disclosed in the prior art, without special restrictions, as long as its molecular weight and amino content are met. In the following specific embodiments, PEEK, 3,5-dihydroxybenzoic acid, and 4,4-difluorobenzophenone are all purchased from Hubei Jusheng Technology Co., Ltd. The present invention is further described below in the form of specific examples.

[0026] Example 1 A wear-resistant PEEK composite material comprises the following raw materials in parts by weight: 100 parts of PEEK, 2 parts of aramid fiber, and 10 parts of silicone-modified carbon fiber; wherein, Siloxane-modified carbon fibers were prepared by the following method: At 100°C, the carbon fiber was treated with a 30% nitric acid solution for 4 hours to obtain surface oxidized carbon fiber; terminal amino polydimethylsiloxane (weight-average molecular weight of 5000, amino content of 0.1 mmol / g) was added to sufficient acetone, and the surface oxidized carbon fiber was added, the mass ratio of terminal amino polydimethylsiloxane to surface oxidized carbon fiber was 2:10, and the carbon fiber was immersed at room temperature for 6 hours. After treatment, it was washed and dried to obtain a carbon fiber with a diameter of 1 μm and a length of 0.5 mm.

[0027] The aramid fiber has a diameter of 5 μm and a length of 5 mm.

[0028] The wear-resistant PEEK composite material is prepared by the following method: After PEEK, aramid fiber, and silicone modified carbon fiber are fully mixed, they are placed in a mold for hot pressing at a temperature of 390°C and a pressure of 10 MPa; they are then annealed at a temperature of 250°C and a time of 1 hour.

[0029] Example 2 A wear-resistant PEEK composite material comprises the following raw materials in parts by weight: 100 parts of PEEK, 3 parts of aramid fiber, and 7 parts of silicone-modified carbon fiber; wherein, Siloxane-modified carbon fibers were prepared by the following method: At 100°C, the carbon fiber was treated with a 30% nitric acid solution for 6 hours to obtain surface oxidized carbon fiber; terminal amino polydimethylsiloxane (weight-average molecular weight of 20,000, amino content of 0.5 mmol / g) was added to sufficient acetone, and the surface oxidized carbon fiber was added, the mass ratio of terminal amino polydimethylsiloxane to surface oxidized carbon fiber was 2.4:10, and the carbon fiber was immersed at room temperature for 8 hours. After treatment, it was washed and dried to obtain a carbon fiber with a diameter of 1 μm and a length of 0.5 mm.

[0030] The aramid fiber is a plasma-treated aramid fiber with a diameter of 12 μm and a length of 10 mm. The plasma treatment medium is argon gas, the gas flow rate is 10 cm / min, the plasma generation power is 50 W, and the treatment time is 50 s.

[0031] The wear-resistant PEEK composite material is prepared by the following method: After PEEK, aramid fiber, and silicone modified carbon fiber are fully mixed, they are placed in a mold for hot pressing at a temperature of 390°C and a pressure of 10 MPa; they are then annealed at a temperature of 250°C and a time of 1 hour.

[0032] Example 3 A wear-resistant PEEK composite material comprises the following raw materials in parts by weight: 70 parts of PEEK, 30 parts of carboxylated PEEK, 5 parts of aramid fiber, and 5 parts of silicone-modified carbon fiber; wherein, Siloxane-modified carbon fibers were prepared by the following method: At 100°C, the carbon fiber was treated with a 30% nitric acid solution for 6 hours to obtain surface oxidized carbon fiber; terminal amino polydimethylsiloxane (weight-average molecular weight of 20,000, amino content of 0.5 mmol / g) was added to sufficient acetone, and the surface oxidized carbon fiber was added. The mass ratio of terminal amino polydimethylsiloxane to surface oxidized carbon fiber was 3:10. The carbon fiber was immersed at room temperature for 8 hours. After treatment, it was washed and dried to obtain a carbon fiber with a diameter of 1 μm and a length of 0.5 mm.

[0033] The aramid fiber is a plasma-treated aramid fiber with a diameter of 12 μm and a length of 10 mm. The plasma treatment medium is argon gas, the gas flow rate is 10 cm / min, the plasma generation power is 50 W, and the treatment time is 50 s.

[0034] The carboxymethylation degree of carboxylated PEEK is 18%, and the preparation method is as follows: Mix 4,4-difluorobenzophenone, hydroquinone, 3,5-dihydroxybenzoic acid, alkali metal carbonate and sufficient toluene, wherein the molar ratio of 4,4-difluorobenzophenone, hydroquinone and 3,5-dihydroxybenzoic acid is 70:18:12, and the amount of potassium carbonate and sodium carbonate is 10% of the total mass of the three monomers respectively. Prepolymerize at 200°C under nitrogen protection for 1 hour, then heat to 240°C and polymerize for 1 hour. After the reaction, pour into water, add hydrochloric acid for acidification, wash and dry to obtain the product.

[0035] The wear-resistant PEEK composite material is prepared by the following method: After PEEK, aramid fiber, and silicone modified carbon fiber are fully mixed, they are placed in a mold for hot pressing at a temperature of 390°C and a pressure of 10 MPa; they are then annealed at a temperature of 250°C and a time of 1 hour.

[0036] Example 4 The difference from Example 3 is that the amount of PEEK added is 74 parts, the amount of carboxylated PEEK is 26 parts, and the degree of carboxymethylation of the carboxylated PEEK is 20%. PEEK with a carboxymethylation degree of 20% can be obtained by adjusting the amount of monomers used, which will not be repeated here.

[0037] Example 5 The difference from Example 3 is that the added amount of PEEK is 80 parts, the added amount of carboxylated PEEK is 20 parts, and the degree of carboxymethylation of the carboxylated PEEK is 25%.

[0038] Example 6 The difference from Example 3 is that during the preparation of the siloxane-modified carbon fibers, the mass ratio of amino-terminated polydimethylsiloxane to surface-oxidized carbon fibers is 4:10.

[0039] Example 7 The difference from Example 3 is that the added amount of PEEK is 60 parts and the added amount of carboxylated PEEK is 40 parts.

[0040] Example 8 The difference from Example 3 is that the carboxylation degree of the carboxylated PEEK is 30%.

[0041] Comparative Example 1 The difference from Example 3 is that during the preparation of the siloxane-modified carbon fiber, the amino-terminated polydimethylsiloxane is replaced by an equal amount of γ-aminopropyltriethoxysilane.

[0042] Comparative Example 2 The difference from Example 3 is that the siloxane-modified carbon fibers are replaced by untreated carbon fibers.

[0043] Comparative Example 3 The difference from Example 3 is that no siloxane-modified carbon fibers are added.

[0044] Test example The wear-resistant PEEK composite materials prepared in the above examples and comparative examples were tested for impact strength, wear resistance, and heat resistance. Impact strength was tested according to ASTM D256-2010. Wear resistance was tested according to GB / T 3960-2016, with friction performance measured by wear rate. Heat resistance was tested according to ASTM D648, with heat deformation temperature at 1.86 MPa. The results are shown in Table 1 below.

[0045] Table 1

[0046] The results show that the impact strength of the PEEK composite material provided by the present invention is 38kJ / m 2 As mentioned above, the friction coefficient is ≤0.1 and the thermal deformation temperature is higher than 240°C, that is, the PEEK composite material of the present application has excellent impact resistance, friction performance and heat resistance, which makes up for the defects of the existing PEEK material.

[0047] Compared with Example 3, the impact resistance, wear resistance and heat resistance of the materials obtained in Comparative Examples 1-3 are all reduced, while in Example 6, the siloxane in the siloxane-modified carbon fiber is excessive, and its impact resistance and heat deformation temperature are reduced. It can be seen that the addition of siloxane-modified carbon fiber helps to improve the performance of the material, but the amount of siloxane in the carbon fiber needs to be controlled.

[0048] In summary, the PEEK composite material provided by the present invention has excellent impact resistance, wear resistance and heat resistance, which makes up for the defects of the existing PEEK material used in ball valves.

[0049] The above description of the embodiments is intended to facilitate understanding and application of the invention by those skilled in the art. It will be apparent that those skilled in the art can readily make various modifications to these embodiments and apply the general principles described herein to other embodiments without requiring inventive effort. Therefore, the present invention is not limited to the above-described embodiments. Improvements and modifications made by those skilled in the art based on the disclosure of the present invention, without departing from the scope of the present invention, should be within the scope of protection of the present invention.

Claims

1. A wear-resistant PEEK composite material, characterized in that: The invention comprises the following raw materials in parts by weight: 100 parts of PEEK, 2 to 5 parts of aramid fiber, and 5 to 10 parts of silicone-modified carbon fiber.

2. The wear-resistant PEEK composite material according to claim 1, characterized in that: The diameter of the siloxane-modified carbon fiber is 1 to 5 μm, and the length is 0.5 to 5 mm.

3. The wear-resistant PEEK composite material according to claim 1, characterized in that: The siloxane-modified carbon fiber is obtained by impregnating and modifying carbon fiber with amino-terminated polydimethylsiloxane.

4. The wear-resistant PEEK composite material according to claim 3, characterized in that: The amino-terminated polydimethylsiloxane has a weight average molecular weight of 5,000 to 20,000 and an amino group content of 0.1 to 0.5 mmol / g.

5. The wear-resistant PEEK composite material according to claim 3 or 4, characterized in that: The preparation method of the siloxane-modified carbon fiber comprises the following steps: (1) Treating carbon fibers with an oxidant at 100-120°C for 4-6 hours to obtain surface-oxidized carbon fibers; (2) Add amino-terminated polydimethylsiloxane to acetone, add surface oxidized carbon fiber, and immerse for 6 to 8 hours at room temperature. After treatment, wash and dry to obtain the product.

6. The wear-resistant PEEK composite material according to claim 5, characterized in that: The mass ratio of amino-terminated polydimethylsiloxane to surface oxidized carbon fiber is (2-3):

10.

7. The wear-resistant PEEK composite material according to claim 1, characterized in that: The aramid fiber has a diameter of 5 to 12 μm and a length of 5 to 10 mm.

8. The method for preparing the wear-resistant PEEK composite material according to any one of claims 1 to 7, characterized in that: The following steps are involved: After PEEK, aramid fiber and silicone modified carbon fiber are fully mixed, they are placed in a mold for hot pressing at a temperature of 390-400°C and a pressure of 10-15 MPa; and then annealing is performed to obtain the product.

9. Use of the wear-resistant PEEK composite material according to any one of claims 1 to 7 or the wear-resistant PEEK composite material prepared by the preparation method according to claim 8 in preparing a reversing valve for a bellows pump.

10. The use according to claim 9, characterized in that The application includes using the wear-resistant PEEK composite material to prepare at least one of a valve body, a valve sleeve, and a valve core in a reversing valve for a bellows pump.

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