Polyaryletherketone alloy material and preparation method thereof

Abstract

According to the polyaryletherketone alloy material and the preparation method thereof, PEEK and PEK can be mixed through the method, and meanwhile, a PEK material microstructure is formed in the alloy, so that the fiber reinforcement effect is achieved to a certain extent. Compared with simple melt blending, the polyaryletherketone alloy material prepared by the scheme has higher mechanical properties and higher use temperature.

Description

Technical Field

[0001] The present invention belongs to the technical field of polymer materials, and particularly relates to a high-performance polyaryletherketone alloy material and a preparation method thereof. Background Art

[0002] As a semi-crystalline special engineering plastic, polyetheretherketone (PEEK) has been widely used in the high-end manufacturing field due to its excellent mechanical properties, chemical corrosion resistance and flame retardancy. However, its glass transition temperature (Tg = 143 °C) and melting point (Tm = 334 °C) limit its reliability for long-term use above 150 °C, and problems such as strength attenuation and dimensional instability are likely to occur in a high-temperature environment. In the prior art, fiber-reinforced modification is usually used to improve the heat resistance of PEEK, but the addition of fibers will greatly damage the original flexibility of the material, and at the same time, due to the poor interfacial compatibility between the fibers and the substrate PEEK, local structural defects of the material will also be generated, resulting in stress concentration.

[0003] Polyetherketone (PEK) is a high-performance semi-crystalline thermoplastic engineering plastic. The alternately arranged ether bonds and ketone groups in its molecular chain endow it with excellent high-temperature resistance, mechanical strength and chemical stability. Compared with PEEK, PEK has a lower ether-ketone ratio, so it has a higher Tg (153 °C) and Tm (370 °C), and can still maintain excellent dimensional stability and creep resistance in a high-temperature environment.

[0004] The preparation of polyaryletherketone alloy can be achieved by blending PEEK and PEK through a twin-screw extruder. However, due to the differences in their melting points and processing temperatures, as well as the requirements of the material's own thermal stability for processing conditions, the processing temperature and process cannot be simply made compatible with high temperatures. Summary of the Invention

[0005] In order to solve the above problems and improve the strength and service temperature of PEEK while maintaining the original elongation at break and flexibility of the material, the present application designs a polyaryletherketone alloy material and a preparation method thereof. Through this method, the microstructure of PEK material can be formed inside the alloy while PEEK and PEK are mixed, thus achieving a fiber-reinforcing effect to a certain extent. Compared with simple melt blending, the polyaryletherketone alloy material prepared by this solution has higher mechanical properties and a higher service temperature. The specific solutions include: Mix PEEK and PEK powder evenly in a certain proportion, and use a twin-screw extruder to granulate at 355 - 365 °C; bake the obtained polyaryletherketone alloy particles at 195 - 205 °C for 1 - 4 hours, and naturally cool to room temperature to obtain the product polyaryletherketone alloy particles; inject the above polyaryletherketone alloy particles at a certain temperature to obtain an injection molded part of polyaryletherketone alloy particles.

[0006] Preferably, the mass ratio of the above-mentioned PEEK to PEK powder is 95:5 to 65:35; Preferably, the injection molding temperature of the above-mentioned polyaryletherketone alloy particles is 380 - 385 °C.

[0007] Under the same conditions, use an injection molding machine to prepare standard specimens and test the tensile strength, flexural strength, and heat distortion temperature. Beneficial effects

[0008] Using PEK as a material to reinforce PEEK, the two have extremely similar molecular chain structures, which can avoid structural defects caused by the separation of the matrix and the filler during the molding process. Moreover, the cold crystallization peaks of both are between 180 - 190 °C, which can ensure that the annealing process of the injection-molded product has the same progress for both components, avoiding material defects caused by uneven stress release during the annealing process.

[0009] After pelletizing, drying the alloy particles at 195 - 205 °C for 1 - 4 hours can release the stress in the molecular chain, improve the crystallinity, reduce the water absorption rate, thoroughly dry the water vapor, and reduce defects such as microbubbles in the injection-molded parts.

[0010] At the pelletizing stage, pre-plasticize the matrix at 355 - 365 °C (higher than the melting point of PEEK but lower than the melting point of PEK). When injection molding, control the processing temperature at 380 - 385 °C (higher than the melting point of PEK) to promote partial melting of PEK, and form a fiber-like reinforcement structure under the push of the extruder screw. This "gradient activation" process not only avoids risks such as thermal decomposition and thermal crosslinking of the material, but also forms an interpenetrating network structure, making the polyaryletherketone alloy have better mechanical properties and a higher heat distortion temperature. Specific embodiments Example 1

[0011] Fully mix PEEK and PEK powder in a ratio of 70:30, and granulate using a twin-screw extruder at 360 °C; dry the obtained polyaryletherketone alloy particles at 200 °C for 3 hours, and naturally cool to room temperature to obtain the product polyaryletherketone alloy particles; injection mold the above polyaryletherketone alloy particles at 385 °C to obtain an injection-molded part of polyaryletherketone alloy particles.

[0012] Under the same conditions, use an injection molding machine to prepare standard specimens and test the tensile strength, flexural strength, and heat distortion temperature. The experimental results are shown in Table 1. Example 2

[0013] Mix the PEEK and PEK powders evenly at a ratio of 95:5, and granulate them using a twin-screw extruder at 360 °C; dry the obtained polyaryletherketone alloy particles at 200 °C for 3 hours and cool them naturally to room temperature to obtain the polyaryletherketone alloy particle product; injection-mold the above polyaryletherketone alloy particles at 385 °C to obtain an injection-molded part of the polyaryletherketone alloy particles.

[0014] Under the same conditions, prepare standard specimens using an injection molding machine and test the tensile strength, flexural strength, and heat distortion temperature. The experimental results are shown in Table 1. Comparative Example 1

[0015] Mix the PEEK and PEK powders evenly at a ratio of 70:30, and granulate them using a twin-screw extruder at 360 °C; dry the obtained polyaryletherketone alloy particles at 200 °C for 3 hours and cool them naturally to room temperature to obtain the polyaryletherketone alloy particle product; injection-mold the above polyaryletherketone alloy particles at 360 °C to obtain an injection-molded part of the polyaryletherketone alloy particles.

[0016] Under the same conditions, prepare standard specimens using an injection molding machine and test the tensile strength, flexural strength, and heat distortion temperature. The experimental results are shown in Table 1.

[0017] In Comparative Example 1, both the granulation and injection molding temperatures were 360 °C, which is lower than the melting point of the PEK material. The tensile, flexural strengths, and heat distortion temperature of the material were all lower than the parameters of the alloy in Example 1. This is because the PEK did not form a microstructure in the alloy but remained in the form of the original powder particles. Comparative Example 2

[0018] Mix the PEEK and PEK powders evenly at a ratio of 70:30, and granulate them using a twin-screw extruder at 385 °C; dry the obtained polyaryletherketone alloy particles at 200 °C for 3 hours and cool them naturally to room temperature to obtain the polyaryletherketone alloy particle product; injection-mold the above polyaryletherketone alloy particles at 360 °C to obtain an injection-molded part of the polyaryletherketone alloy particles.

[0019] Under the same conditions, prepare standard specimens using an injection molding machine and test the tensile strength, flexural strength, and heat distortion temperature. The experimental results are shown in Table 1.

[0020] In Comparative Example 2, the granulation temperature was 385°C and the injection molding temperature was 360°C. Due to the superposition of temperature and screw shear in the granulation stage, the PEK material was extremely uniformly mixed in the PEEK matrix. And during the injection molding process, PEK was in a crystalline state, which led to the absence of fiber-like structures in the alloy to provide mechanical properties and possible microdefects such as agglomeration of PEK small particles. Therefore, the tensile strength of the material in Comparative Example 2 was even lower than that of the PEEK substrate (about 95 MPa), which was caused by structural defects. Comparative Example 3

[0021] The PEEK and PEK powder materials were fully and uniformly mixed at a ratio of 70:30, and granulation was carried out at 385°C using a twin-screw extruder; the obtained polyaryletherketone alloy particles were baked at 200°C for 3 hours and naturally cooled to room temperature to obtain the polyaryletherketone alloy particles; the above polyaryletherketone alloy particles were injection molded at 385°C to obtain an injection molded part of polyaryletherketone alloy particles.

[0022] Under the same conditions, standard specimens were prepared using an injection molding machine to test the tensile strength, flexural strength, and heat distortion temperature. The experimental results are shown in Table 1.

[0023] In Comparative Example 3, both the granulation temperature and the injection molding temperature were 385°C, which was higher than the melting point of the PEK material. Due to the superposition of temperature and screw shear in the granulation stage, the PEK material was extremely uniformly mixed in the PEEK matrix. Using 385°C in the injection molding stage did not cause obvious microstructural defects, but the strength decreased compared to the presence of PEK fiber-like structures in Example 1. This is also the most common processing state of most polymer alloy materials.

[0024] Table 1 Tensile strength, flexural strength, and heat distortion temperature values at different temperatures

[0025]

Claims

1. A preparation method of a polyaryletherketone alloy material, characterized in that, It includes the following steps: Fully mix PEEK and PEK powder evenly in a certain proportion, and granulate using a twin-screw extruder at 355 - 365 °C; bake the obtained polyaryletherketone alloy particles at 195 - 205 °C for 1 - 4 hours, and naturally cool to room temperature to obtain the product polyaryletherketone alloy particles; injection mold the above polyaryletherketone alloy particles at a certain temperature to obtain an injection molded part of polyaryletherketone alloy particles.

2. The preparation method of a polyaryletherketone alloy material according to claim 1, characterized in that, The mass ratio of the PEEK to the PEK powder is 95:5 - 65:

35.

3. The preparation method of a polyaryletherketone alloy material according to claim 1, characterized in that, The injection molding temperature of the polyaryletherketone alloy particles is 380 - 385 °C.

4. A method for preparing a polyaryletherketone alloy material according to claim 1, the polyaryletherketone alloy material prepared under the condition that the mass ratio of PEEK to PEK is 7:3, characterized in that, Its tensile strength ≥ 104 MPa; flexural strength ≥ 172 MPa; impact strength ≥ 2 kJ / m 2 ; heat distortion temperature ≥ 155 °C.

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