Damp-heat-resistant high-flexibility flame-retardant polyether-ether-ketone modified material and preparation method thereof

Abstract

The invention relates to the field of polyether-ether-ketone, in particular to a damp-heat-resistant high-flexibility flame-retardant polyether-ether-ketone modified material and a preparation method thereof. According to the damp-heat-resistant high-flexibility flame-retardant polyether-ether-ketone modified material, the main chain of polyether-ether-ketone contains a siloxane monomer, and the siloxane monomer comprises double-amino-terminated polydimethylsiloxane. According to the invention, amino-terminated polydimethylsiloxane is introduced into a traditional PEEK main chain as a comonomer. According to the technical scheme of chemical bonding and embedding of siloxane chain segments into a main chain instead of traditional physical blending, the phase separation problem of physical blending is avoided, the siloxane chain segments are uniformly dispersed in the main chain, and the long-term stability of the material is remarkably improved. According to the present invention, the bond energy of the Si-O bond of the amino-terminated polydimethylsiloxane is low, the flexibility of the molecular chain segment is high, such that the glass transition temperature of the PEEK can be significantly reduced so as to further improve the elongation at break, and the hydrophobic methyl group of the amino-terminated polydimethylsiloxane can reduce the water absorption rate of the material so as to avoid the hydrolysis aging of the material in the hot and humid environment.

Description

Technical Field

[0001] This application relates to the field of polyetheretherketone, and in particular to a moisture and heat resistant, highly flexible and flame retardant polyetheretherketone modified material and its preparation method. Background Art

[0002] Polyetheretherketone (PEEK) is a semi-crystalline special engineering plastic. Due to the rigid aromatic ring structure, ether bonds and ketone groups in its main chain, it has excellent high temperature resistance, mechanical strength and chemical stability, and is widely used in aerospace, electronic packaging, medical devices and other fields. However, traditional PEEK materials are prone to hydrolysis aging in a humid and hot environment, resulting in a significant decline in mechanical properties. At the same time, its molecular chain has strong rigidity, and the elongation at break is usually less than 50%, making it difficult to meet the dual requirements of high flexibility and moisture and heat resistance of materials in emerging fields such as flexible electronic devices, wearable devices and bio-implants. In addition, the flame retardant performance of PEEK also has limitations, its limiting oxygen index is not good, and it is easy to melt and drip in a high temperature or open fire environment.

[0003] To improve the moisture and heat resistance, flexibility and flame retardancy of PEEK, existing technologies mainly adopt physical blending or chemical copolymerization modification strategies. The flexibility is improved by introducing silicone elastomers or inorganic fillers. However, physical blending has a risk of phase separation, and the fillers are likely to migrate and precipitate after long-term use, resulting in performance attenuation. Or functional monomers are introduced into the PEEK main chain through copolymerization reaction, but its cost is high and it may reduce the processability of the material.

[0004] In view of the above existing technologies, the inventor found that existing solutions mostly focus on improving a single performance, lacking the synergistic optimization of moisture and heat resistance, flexibility and flame retardancy. For example, although introducing PDMS can toughen the material, its non-reactive blending leads to insufficient interfacial bonding force, and the performance deteriorates significantly in a humid and hot environment. At the same time, traditional thermal polymerization requires a long-time high-temperature reaction, which is easy to cause molecular chain degradation, resulting in a wide molecular weight distribution and unstable mechanical properties. Although there are attempts with microwave processes, the problem of efficient bonding of functional monomers has not been solved. Summary of the Invention

[0005] In order to solve the above technical problems, this application provides a moisture and heat resistant, highly flexible and flame retardant polyetheretherketone modified material and its preparation method.

[0006] In the first aspect, this application provides a moisture and heat resistant, highly flexible and flame retardant polyetheretherketone modified material, adopting the following technical solution: A moisture and heat resistant, highly flexible and flame retardant polyetheretherketone modified material, wherein the polyetheretherketone main chain contains a silicone monomer, and the silicone monomer includes bis(amino) terminated polydimethylsiloxane.

[0007] Through the above technical solution, a diamino-terminated polydimethylsiloxane is introduced as a comonomer into the traditional PEEK main chain. Through chemical bonding, the siloxane chain segments are embedded in the main chain, replacing the traditional physical blending technical solution, avoiding the phase separation problem of physical blending. The siloxane chain segments are uniformly dispersed in the main chain, and the long-term stability of the material is significantly improved. Due to the low bond energy of the Si-O bond in the diamino-terminated polydimethylsiloxane and the high flexibility of the molecular chain segments, the glass transition temperature of PEEK can be significantly reduced, further improving the elongation at break. At the same time, the hydrophobic methyl groups of the diamino-terminated polydimethylsiloxane reduce the water absorption rate of the material, improve the tensile strength retention rate, and avoid hydrolysis aging in a humid and hot environment.

[0008] Further, it is characterized in that the molecular formula of the diamino-terminated polydimethylsiloxane is NH2-(CH2)3-[Si(CH3)2O] 10 -(CH2)3-NH2.

[0009] Further, the PEEK main chain also includes a phosphazene monomer, and the phosphazene monomer includes a hexachlorocyclotriphosphazene derivative with a phenoxy substituent.

[0010] Through the above technical solution, the present application further introduces a hexachlorocyclotriphosphazene derivative with a phenoxy substituent as a comonomer to form a quaternary copolymer. Since the P-N bond in the phosphazene ring decomposes at high temperature to generate PO· free radicals, which capture the H· / OH· free radicals in the combustion chain reaction, the flame retardant performance can be further improved. At the same time, the rigid structure of the phosphazene ring is complementary to the flexible siloxane chain segments, improving the mechanical properties of the prepared PEEK composite material.

[0011] Further, the hexachlorocyclotriphosphazene derivative is hexaphenoxycyclotriphosphazene formed by the reaction of hexachlorocyclotriphosphazene with sodium phenoxide to replace the chlorine atoms.

[0012] Through the above technical solution, the present application defines the phosphazene monomer as hexaphenoxycyclotriphosphazene formed by the reaction of hexachlorocyclotriphosphazene with sodium phenoxide, clarifying the substituent type and synthesis method. Since the thermal decomposition temperature of the phosphazene ring is further increased after the chlorine atoms are replaced by phenoxy groups, thermal decomposition during the processing is avoided. At the same time, the nucleophilicity of sodium phenoxide is stronger than that of phenol, the reaction time is shortened, and the monomer yield is increased, avoiding side reactions in subsequent polymerization.

[0013] In the second aspect, the present application provides a method for preparing a moisture and heat resistant, highly flexible and flame retardant PEEK modified material, adopting the following technical solution: A method for preparing a moisture and heat resistant, highly flexible and flame retardant PEEK modified material includes the following preparation steps: 4,4'-Difluorobenzophenone, bisphenol A and potassium carbonate are stirred and mixed and placed in a reaction kettle. N-methylpyrrolidone is added and stirred and mixed. After heating and maintaining the temperature for reaction, a low molecular weight prepolymer is collected; The prepolymer is placed in a reaction device. A phosphazene monomer and a bis-terminal amino polydimethylsiloxane are added. After supplementing N-methylpyrrolidone, stirring and mixing are continued, and a mixed solution is collected; The mixed solution is taken and subjected to gradient microwave-assisted heating treatment. After cooling, deionized water is injected, precipitated and filtered. The filter cake is collected and dried, and then extruded and granulated to prepare the heat and humidity resistant, highly flexible and flame retardant polyether ether ketone modified material.

[0014] Through the above technical solution, the present application optimizes the preparation process. First, a low molecular weight PEEK prepolymer is synthesized, then copolymerized with phosphazene and siloxane monomers by microwave, and finally processed to obtain the final material. The low molecular weight PEEK prepolymer provides active end groups for subsequent copolymerization, and the mechanical properties are stable. Microwave radiation selectively heats polar monomers, the reaction time is further shortened, and the molecular chain breakage caused by high temperature is avoided.

[0015] Further, the molar ratio of the addition amounts of 4,4'-difluorobenzophenone, bisphenol A, the phosphazene monomer and the bis-terminal amino polydimethylsiloxane is 1:(0.8 - 1.2):(0.1 - 0.3):(0.1 - 0.2).

[0016] Through the above technical solution, the present application limits the addition ratio of each component substance, so that the main chain ether bonds are fully formed, avoiding crosslinking caused by the residual fluorine end groups. At the same time, the phosphazene ratio is optimized to achieve the best balance between flame retardancy and flexibility.

[0017] Further, the gradient microwave-assisted heating treatment includes the following steps: First, preheat at 150 - 200W for 5 minutes, and then increase the power to 300 - 350W for heating treatment for 5 minutes to complete the gradient microwave-assisted heating treatment.

[0018] Through the above technical solution, the present application optimizes the microwave-assisted heating treatment plan. In the preheating stage, low-power preheating promotes the dissolution of monomers and the dispersion of prepolymers, avoiding the degradation of prepolymers caused by local overheating; then, high-power excitation selectively heats polar monomers, the reaction efficiency is improved, and the pulse microwave temperature control accuracy is excellent, avoiding thermal runaway.

[0019] Further, the temperature for heating and maintaining the temperature for reaction is 145 - 160 °C.

[0020] In summary, the present application has the following beneficial effects: First, the present application introduces bis(aminopropyl) polydimethylsiloxane as a comonomer into the traditional PEEK main chain. Through chemical bonding, the siloxane chain segments are embedded in the main chain, replacing the traditional physical blending technical solution, avoiding the phase separation problem of physical blending. The siloxane chain segments are uniformly dispersed in the main chain, and the long-term stability of the material is significantly improved. Due to the low bond energy of the Si-O bond in bis(aminopropyl) polydimethylsiloxane and the high flexibility of the molecular chain segments, the glass transition temperature of PEEK can be significantly reduced, further increasing the elongation at break. At the same time, the hydrophobic methyl groups of bis(aminopropyl) polydimethylsiloxane reduce the water absorption rate of the material, improve the tensile strength retention rate, and avoid hydrolysis aging in a humid and hot environment.

[0021] Second, the present application further introduces a phenoxy-substituted hexachlorocyclotriphosphazene derivative as a comonomer to form a quaternary copolymer. Since the P-N bond in the phosphazene ring decomposes at high temperature to generate PO· free radicals, which capture H· / OH· free radicals in the combustion chain reaction, the flame retardancy can be further improved. At the same time, the rigid structure of the phosphazene ring is complementary to the flexible siloxane chain segments, improving the mechanical properties of the prepared PEEK composite material.

[0022] Third, the present application optimizes the microwave-assisted heating treatment scheme. In the preheating stage, low-power preheating promotes the dissolution of monomers and the dispersion of prepolymers, avoiding the degradation of prepolymers caused by local overheating; then, high-power excitation is used for selective heating of polar monomers, improving the reaction efficiency, and the pulsed microwave temperature control has excellent accuracy, avoiding thermal runaway. Detailed implementation mode

[0023] The following further elaborates on the present application with reference to the examples.

[0024] Examples Example 1: Take 218.19 g of 4,4'-difluorobenzophenone, 182.62 g of bisphenol A, and 85.78 g of bis(aminopropyl) polydimethylsiloxane according to a molar ratio of 1:0.8:0.1. After mixing 4,4'-difluorobenzophenone and bisphenol A, add 303.60 g of potassium carbonate and 3157 g of N-methylpyrrolidone, stir and mix, and place them in a reaction kettle. Under a nitrogen atmosphere, heat to 150°C at a rate of 5°C / min, stir and react at 300 rpm for 3 h, and terminate the reaction after monitoring that the viscosity reaches 320 mPa·s to obtain a low-molecular-weight prepolymer; Then, place the low-molecular-weight prepolymer in a reaction device, first perform preheating treatment at 150 W for 5 min, then increase the power to 300 W and heat for 5 min. After cooling to 50°C, inject 5 L of deionized water, precipitate, wash successively with ethanol, 0.1 M HCl, and water, filter, collect the filter cake, and dry it in vacuo at 80°C for 24 h. Extrude and pelletize it with a twin-screw extruder at 300°C to prepare the heat and humidity resistant, highly flexible, flame retardant polyether ether ketone modified material.

[0025] Example 2: Take 218.19 g of 4,4'-difluorobenzophenone, 228.28 g of bisphenol A, and 85.78 g of bis(aminopropyl)polydimethylsiloxane according to a molar ratio of 1:1:0.1. After mixing 4,4'-difluorobenzophenone and bisphenol A, add 303.60 g of potassium carbonate and 3.16 L of N-methylpyrrolidone, stir and mix them, and place them in a reaction kettle. Under a nitrogen atmosphere, heat up to 150 °C at a rate of 5 °C / min, stir and react at 300 rpm for 3 h. After monitoring that the viscosity reaches 320 mPa·s, terminate the reaction to obtain a low-molecular-weight prepolymer; Then place the low-molecular-weight prepolymer in a reaction device. First, preheat it at 175 W for 5 min, then increase the power to 325 W and heat-treat it for 5 min. After cooling to 50 °C, inject 5 L of deionized water, precipitate, and wash it successively with ethanol, 0.1 M HCl, and water, then filter. Collect the filter cake and dry it in vacuo at 80 °C for 24 h, and extrude and pelletize it with a twin-screw extruder at 320 °C to prepare the heat and humidity resistant, highly flexible, flame-retardant polyether ether ketone modified material.

[0026] Example 3: Take 218.19 g of 4,4'-difluorobenzophenone, 273.94 g of bisphenol A, and 171.56 g of bis(aminopropyl)polydimethylsiloxane according to a molar ratio of 1:1.2:0.2. After mixing 4,4'-difluorobenzophenone and bisphenol A, add 303.60 g of potassium carbonate and 2.5 L of N-methylpyrrolidone, stir and mix them, and place them in a reaction kettle. Under a nitrogen atmosphere, heat up to 150 °C at a rate of 5 °C / min, stir and react at 300 rpm for 3 h. After monitoring that the viscosity reaches 320 mPa·s, terminate the reaction to obtain a low-molecular-weight prepolymer; Then place the low-molecular-weight prepolymer in a reaction device. First, preheat it at 200 W for 5 min, then increase the power to 350 W and heat-treat it for 5 min. After cooling to 50 °C, inject 5 L of deionized water, precipitate, and wash it successively with ethanol, 0.1 M HCl, and water, then filter. Collect the filter cake and dry it in vacuo at 80 °C for 24 h, and extrude and pelletize it with a twin-screw extruder at 340 °C to prepare the heat and humidity resistant, highly flexible, flame-retardant polyether ether ketone modified material.

[0027] Example 4: Take 218.19 g of 4,4'-difluorobenzophenone, 228.28 g of bisphenol A, 75.60 g of phosphazene monomer, and 85.78 g of bis(aminopropyl)polydimethylsiloxane according to a molar ratio of 1:1:0.1:0.1. After mixing 4,4'-difluorobenzophenone and bisphenol A, add 303.60 g of potassium carbonate and 5 L of N-methylpyrrolidone, stir and mix them, and place them in a reaction kettle. Under a nitrogen atmosphere, heat up to 150 °C at a rate of 5 °C / min, stir and react at 300 rpm for 3 h. After monitoring that the viscosity reaches 320 mPa·s, terminate the reaction to obtain a low-molecular-weight prepolymer; Next, place the low-molecular-weight prepolymer in a reaction device, add phosphazene monomer and bis(amino-terminated) polydimethylsiloxane, and add NMP to a solid content of 15%. After preheating at 175 W for 5 min, increase the power to 325 W and heat-treat for 5 min. After cooling to 50 °C, inject 5 L of deionized water, precipitate, wash successively with ethanol, 0.1 M HCl, and water, then filter. Collect the filter cake and dry it under vacuum at 80 °C for 24 h, and then extrude and pelletize it with a twin-screw extruder at 320 °C to obtain the moisture and heat-resistant, highly flexible, flame-retardant polyether ether ketone modified material.

[0028] Example 5: Take 218.19 g of 4,4'-difluorobenzophenone, 228.28 g of bisphenol A, 151.20 g of phosphazene monomer, and 85.78 g of bis(amino-terminated) polydimethylsiloxane according to a molar ratio of 1:1:0.2:0.1. After mixing 4,4'-difluorobenzophenone and bisphenol A, add 303.60 g of potassium carbonate and 5.3 L of N-methylpyrrolidone, stir and mix, and place it in a reaction kettle. Under a nitrogen atmosphere, heat it to 150 °C at a rate of 5 °C / min, stir and react at 300 rpm for 3 h, and terminate the reaction after monitoring that the viscosity reaches 320 mPa·s to obtain a low-molecular-weight prepolymer. Next, place the low-molecular-weight prepolymer in a reaction device, add phosphazene monomer and bis(amino-terminated) polydimethylsiloxane, and add NMP to a solid content of 15%. After preheating at 175 W for 5 min, increase the power to 325 W and heat-treat for 5 min. After cooling to 50 °C, inject 5 L of deionized water, precipitate, wash successively with ethanol, 0.1 M HCl, and water, then filter. Collect the filter cake and dry it under vacuum at 80 °C for 24 h, and then extrude and pelletize it with a twin-screw extruder at 320 °C to obtain the moisture and heat-resistant, highly flexible, flame-retardant polyether ether ketone modified material.

[0029] Example 6: Take 218.19 g of 4,4'-difluorobenzophenone, 228.28 g of bisphenol A, 226.80 g of phosphazene monomer, and 85.78 g of bis(amino-terminated) polydimethylsiloxane according to a molar ratio of 1:1:0.3:0.1. After mixing 4,4'-difluorobenzophenone and bisphenol A, add 303.60 g of potassium carbonate and 5.8 L of N-methylpyrrolidone, stir and mix, and place it in a reaction kettle. Under a nitrogen atmosphere, heat it to 150 °C at a rate of 5 °C / min, stir and react at 300 rpm for 3 h, and terminate the reaction after monitoring that the viscosity reaches 320 mPa·s to obtain a low-molecular-weight prepolymer. Then, place the low molecular weight prepolymer in a reaction device, add phosphazene monomer and amino-terminated polydimethylsiloxane. After adding NMP to make the solid content reach 15%, first preheat it at 175 W for 5 min, then increase the power to 325 W and heat-treat it for 5 min. After cooling to 50 °C, inject 5 L of deionized water, precipitate, wash successively with ethanol, 0.1 M HCl, and water, and then filter. Collect the filter cake and dry it in vacuum at 80 °C for 24 h, and then extrude and pelletize it with a twin-screw extruder at 320 °C to prepare the heat and humidity resistant, highly flexible and flame retardant polyether ether ketone modified material.

[0030] Comparative Example 1 Select traditional polyether ether ketone materials.

[0031] Performance testing Tensile strength: Test according to standard ASTM D638; Limiting oxygen index: Test according to ASTM D2863; Heat and humidity resistance: 1000 h in an environment of 85 °C / 85% RH, and test the tensile strength retention rate after testing.

[0032] The test results are shown in Table 1 below:

[0033] From the data of the examples, it can be found that in this application, by comparing the data of Examples 1-3 and Comparative Example 1, it shows that the technical solution of this application introduces amino-terminated polydimethylsiloxane as a comonomer into the main chain of traditional PEEK. Through chemical bonding, the siloxane chain segments are embedded in the main chain, replacing the traditional physical blending technical solution, avoiding the phase separation problem of physical blending. The siloxane chain segments are uniformly dispersed in the main chain, and the long-term stability of the material is significantly improved. Due to the low bond energy of the Si-O bond in amino-terminated polydimethylsiloxane and the high flexibility of the molecular chain segments, the glass transition temperature of PEEK can be significantly reduced, further improving the elongation at break. At the same time, the hydrophobic methyl groups of amino-terminated polydimethylsiloxane reduce the water absorption rate of the material, improve the tensile strength retention rate, and avoid hydrolysis aging in a humid and hot environment.

[0034] Secondly, by comparing Examples 4-6 with Examples 1-3, this application further introduces a hexachlorocyclotriphosphazene derivative substituted with phenoxy groups as a comonomer to form a quaternary copolymer. Since the P-N bond in the phosphazene ring decomposes at high temperature to generate PO· free radicals, which capture the H· / OH· free radicals in the combustion chain reaction, the flame retardant performance can be further improved.

[0035] This specific embodiment is only an explanation of this application, and it is not a limitation of this application. Those skilled in the art can make modifications without creative contributions to this embodiment according to needs after reading this specification, but as long as they are within the scope of the claims of this application, they are protected by the patent law.

Claims

1. A moisture and heat resistant, highly flexible and flame retardant polyetheretherketone modified material, characterized in that, The polyether ether ketone main chain contains a siloxane monomer, and the siloxane monomer includes bis-terminal amino polydimethylsiloxane.

2. A heat and humidity resistant, highly flexible and flame retardant polyetheretherketone modified material according to claim 1, characterized in that, The molecular formula of the diamino-terminated polydimethylsiloxane is NH2-(CH2)3-[Si(CH3)2O] 10 -(CH2)3-NH2.

3. A moisture and heat resistant, highly flexible and flame retardant polyether ether ketone modified material according to claim 1, characterized in that, The polyether ether ketone main chain also includes a phosphazene monomer, and the phosphazene monomer includes a hexachlorocyclotriphosphazene derivative with a phenoxy substituent.

4. A heat and humidity resistant, highly flexible and flame retardant polyether ether ketone modified material according to claim 3, characterized in that, The hexachlorocyclotriphosphazene derivative is hexaphenoxycyclotriphosphazene formed by reacting hexachlorocyclotriphosphazene with sodium phenoxide to replace chlorine atoms.

5. The preparation method of a moisture and heat resistant, highly flexible and flame retardant polyetheretherketone modified material according to any one of claims 1-4, characterized in that, It includes the following preparation steps: Take 4,4'-difluorobenzophenone, bisphenol A and potassium carbonate, stir and mix them, place them in a reaction kettle, add N-methylpyrrolidone and stir and mix, heat up and keep the temperature for reaction, and collect the low molecular weight prepolymer; Place the prepolymer in a reaction device, add a phosphazene monomer and bis-terminal amino polydimethylsiloxane, supplement N-methylpyrrolidone and continue to stir and mix, and collect the mixed solution; Take the mixed solution and perform gradient microwave-assisted heating treatment, cool it, inject deionized water, precipitate and filter, collect the filter cake and dry it, and extrude and pelletize to prepare the heat and humidity resistant, highly flexible and flame retardant polyether ether ketone modified material.

6. The preparation method of a moisture and heat resistant, highly flexible and flame retardant polyether ether ketone modified material according to claim 5, characterized in that, The molar ratio of the addition amounts of 4,4'-difluorobenzophenone, bisphenol A, phosphazene monomer and bis-terminal amino polydimethylsiloxane is 1:(0.8 - 1.2):(0.1 - 0.3):(0.1 - 0.2).

7. The preparation method of a moisture and heat resistant, highly flexible and flame retardant polyether ether ketone modified material according to claim 5, characterized in that, The gradient microwave-assisted heating treatment includes the following steps: First, preheat at 150 - 200W for 5 minutes, and then increase the power to 300 - 350W for heating treatment for 5 minutes to complete the gradient microwave-assisted heating treatment.

8. The preparation method of a moisture and heat resistant, highly flexible and flame retardant polyether ether ketone modified material according to claim 5, characterized in that, The temperature for heating up and keeping the temperature for reaction is 145 - 160°C.

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