Polyether-ether-ketone resin with microporous structure and preparation method thereof

Abstract

The invention discloses polyether-ether-ketone resin with a microporous structure and a preparation method thereof, and relates to the technical field of high polymer materials. The foaming agent is added in the polymerization reaction process of the polyether-ether-ketone resin, a chemical foaming method and a physical foaming method are combined, and the polyether-ether-ketone resin is foamed through a two-step method, so that the cell density and the foaming ratio of the polyether-ether-ketone resin with a microporous structure are improved; the material density of the polyether-ether-ketone resin with the microporous structure is reduced. According to the invention, a polymerization process and a foaming process of the polyether-ether-ketone resin are combined, and compared with direct foaming of a polyether-ether-ketone material, the prepared polyether-ether-ketone resin with the microporous structure has the advantages of higher cell density, higher foaming ratio and lower material density.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, and in particular to a polyetheretherketone resin with a microporous structure and its preparation method. Background Technology

[0002] Polyetheretherketone (PEEK) is a polymer composed of repeating units containing one ketone bond and two ether bonds in its main chain structure, belonging to the category of special polymer materials. It possesses physicochemical properties such as high temperature resistance and chemical corrosion resistance. As a semi-crystalline polymer, it can be used as a high-temperature structural material and an electrical insulator, and can be composited with glass fiber or carbon fiber to prepare reinforcing materials. This material has extensive applications in aerospace, medical devices (as artificial bone to repair bone defects), and industrial fields. To further broaden the application areas of PEEK materials and fully utilize its advantages as a special engineering plastic, the development of lightweight PEEK is of great significance.

[0003] Polymer foam materials, also known as foamed plastics, possess many excellent properties due to their unique porous structure, such as low density, good impact resistance, high specific strength, excellent thermal insulation, and good sound insulation. Therefore, they are widely used in packaging, insulation, sound insulation, transportation, construction, and medical fields, and have become an indispensable material. With the development of high technology, fields such as national defense, military industry, and aerospace, which operate in harsh environments, require foam materials with properties such as high temperature resistance, corrosion resistance, and high mechanical strength. Therefore, the development of high-performance foam materials has become an important research direction. Research on polyetheretherketone (PEEK) foam materials not only broadens the application fields of PEEK but also has significant implications for lightweighting, low-carbon energy saving, and other aspects of special engineering plastics.

[0004] There are two main methods for preparing polymer foam materials: chemical foaming and physical foaming. Chemical foaming involves adding a chemical foaming agent to the polymer, causing it to decompose and produce gas during processing, or a chemical reaction between raw material components to generate gas, filling the pores of the plastic melt. Physical foaming involves injecting a saturated inert gas at a certain pressure into the polymer, allowing it to fully dissolve, and then rapidly heating or depressurizing the system to achieve a supersaturated state, causing the gas to escape and foam. In addition, there is the phase inversion method for preparing foam materials, but this method is only suitable for soluble polymers and easily leads to solvent residues inside the foam material. As early as the early 1980s, Professor NPSuh proposed the concept of microporous foam plastics and applied supercritical technology to the microporous foaming process. In the early 21st century, supercritical foaming technology for preparing microporous foam plastics has been successfully commercialized.

[0005] In the preparation of foamed materials, critical or supercritical CO2 fluids are difficult to apply in industrial polymerization processes. They can only be used for secondary processing of already molded products to obtain foamed materials. A common method is to place polyetheretherketone (PEEK) or its composite material sheets in a near-critical or supercritical CO2 fluid, and allow them to swell and permeate at a saturation temperature of 320-360℃ and a saturation pressure of 5-30MPa. Then, the pressure is rapidly released to atmospheric pressure and cooled to room temperature. This process is repeated 1-3 times, followed by annealing. The disadvantages of this method are very obvious. First, there are safety hazards caused by high temperature and high pressure. Second, polyetheretherketone (PEEK) materials have extremely high strength, making gas permeation difficult and resulting in low permeability. Furthermore, gas diffusion within the resin is even more challenging. This leads to more permeation near the outer layer of the board and less permeation in the center, resulting in very uneven pore size and severe inconsistencies in the overall performance of the board. To achieve a high foaming ratio, multiple operations are required, making the process very cumbersome and ineffective. Finally, the growth and morphology of the cells are limited by the crystalline regions, limiting the thickness of the pre-foamed board to less than 15mm. Any thicker, and the gas cannot continue to penetrate inwards.

[0006] Chinese patent CN102924743A discloses a method for preparing crystalline polyetheretherketone (PEEK) foam material. This method primarily involves the physical foaming of PEEK beads using a supercritical CO2 process. The resulting foam beads have a uniform cell size and a maximum expansion ratio of 16 times. Furthermore, these foam beads require bonding and molding under high-temperature steam. Due to the narrow temperature difference between the two melting peaks of the foam beads, subsequent steam molding is difficult to control. Therefore, this preparation method involves complex equipment, difficult operation, and high technical requirements, making it unsuitable for industrial application.

[0007] Chinese patent CN102924743A uses crystalline polyetheretherketone (PEEK) as the matrix resin and critical carbon dioxide to prepare crystalline PEEK foam using a rapid depressurization method. To reduce the impact of crystallization on the foaming results, PEEK is heated (330-345℃) to a molten state for foaming, resulting in PEEK foam particles with uniform cell size and a foaming ratio of 6-17 times. Because the foaming process requires the polymer to be in a molten state to increase CO2 solubility while retaining a certain amount of crystals to ensure sufficient melt strength, the foaming window is relatively narrow and difficult to control. Although linear amorphous PEEK has a wider foaming window, it still suffers from low melt strength and low foaming ratio. Furthermore, excessive crystallization not only reduces the solubility of CO2 gas in the PEEK matrix, thus affecting the nucleation density, but also restricts cell growth. Irregular crystal distribution makes it difficult to control the morphology of the PEEK foam.

[0008] Chinese patent CN105367994A discloses a lightweight, wear-resistant microfoamed polyether ether ketone composite material, its preparation method, and its application. The microfoamed polyether ether ketone material is prepared using a high-temperature foaming agent, but the resulting material has a very low foaming ratio, with an apparent density of only 1.35 g / cm³. 3 above.

[0009] In summary, existing methods for preparing polyetheretherketone (PEEK) porous foam materials either have limited expansion ratios or are complex processes. Therefore, to address the shortcomings of existing technologies, this invention provides a PEEK resin with a microporous structure and its preparation method. This overcomes the drawbacks of long gas saturation time, low solubility, and limitations on cell growth and morphology due to crystalline regions in the preparation of high-performance crystalline PEEK foam materials, and has excellent research and development prospects. Summary of the Invention

[0010] The purpose of this invention is to provide a polyetheretherketone (PEEK) resin with a microporous structure and its preparation method. By controlling process parameters, a high-performance foam material with uniform cell morphology and a large foaming ratio is obtained, filling the gap in domestic high-performance crystalline PEEK foaming technology. This invention combines the polymerization process of PEEK resin with the foaming process. Compared with directly foaming PEEK material, the PEEK resin with a microporous structure prepared by this invention has a higher cell density and a higher foaming ratio.

[0011] To achieve the above-mentioned objectives, the technical solution of this invention is as follows:

[0012] In a first aspect, the present invention provides a method for preparing a polyether ether ketone resin with a microporous structure, comprising the following steps: during the polymerization reaction of the polyether ether ketone resin, a chemical foaming agent and a physical foaming agent are used sequentially for foaming.

[0013] In the polymerization process described above, the gas produced by the decomposition of the chemical foaming agent is relatively small in quantity and remains in the material system within the reactor. Its main function is similar to a "gas nucleating agent." At this stage, the material system is in a low-viscosity state. Under stirring, this small amount of gas can be uniformly dispersed and distributed throughout the material system. When the physical foaming agent is introduced into the polymerization reaction, the inert gas uses these previously retained bubbles as nucleation sites for foaming. The inert gas preferentially diffuses into the aforementioned "gas nucleating agent," causing the bubbles to expand and form a cell structure. This foaming method has two significant advantages: First, it results in rapid foaming. In the later stages of the polymerization reaction, the material system in the reactor is in a high-viscosity state. Without these nucleation sites, the gas diffuses through the material solely by pressure, which is slow. Second, it results in uniform foaming. Without these nucleation sites, the foaming efficiency near and away from the liquid surface would differ significantly, leading to a highly uneven gas distribution within the material system.

[0014] Furthermore, the preparation method specifically includes the following steps:

[0015] S1. Under the condition of continuous nitrogen gas introduction, add diphenyl sulfone, hydroquinone, 4,4-difluorobenzophenone, sodium carbonate, potassium carbonate and chemical foaming agent to the high-pressure reactor.

[0016] S2. After heating to the point of melting, start stirring and continue heating to 180°C. Maintain the temperature at 180°C for 1 hour to allow the salt formation reaction to occur.

[0017] S3. Continue heating to the decomposition temperature of the chemical foaming agent, close the valve connecting the high-pressure reactor to the outside, and keep the high-pressure reactor in a sealed state. At this time, the rotation speed is 80-150 r / min, and the constant temperature duration is 20-60 min.

[0018] S4. Continue heating to 310℃. While the temperature reaches 310℃, add a physical foaming agent until the gas pressure inside the reactor reaches 2-50MPa. Maintain the temperature at 310℃ for 1-2 hours, and then depressurize using a pressure reducing device for 1-20 seconds.

[0019] More preferably, the chemical foaming agent is selected from at least one of azodicarbonamide, diisopropyl azodicarbonate, barium azodicarbonate, N,N-dinitrospentamethylenetetramine, p-toluenesulfonamide, 4,4'-oxobis(benzenesulfonamide), and trihydrazine.

[0020] More preferably, the chemical foaming agent is selected from at least one of barium azodicarbonate, p-toluenesulfonamide, 4,4'-oxobis(benzenesulfonamide), and trihydrazine.

[0021] More preferably, the physical foaming agent is selected from at least one of carbon dioxide, helium, neon, and argon.

[0022] More preferably, the physical foaming agent is argon.

[0023] More preferably, the molar ratio of 4,4-difluorobenzophenone to the chemical foaming agent is 100:0.1-12.

[0024] More preferably, after the pressure relief is completed, the process further includes a step of quickly pouring the mixture in the high-pressure reactor onto a smooth stainless steel plate for cooling, wherein the discharge time is controlled within 20-40 seconds.

[0025] The above method requires depressurization and material discharge within a very short time after foaming to allow the material system in the polymerization reactor to be depressurized, discharged, and solidified quickly, which helps to retain the gas content and cell structure in the material to the greatest extent.

[0026] On the other hand, the present invention provides a polyetheretherketone resin with a microporous structure, which is prepared according to the above preparation method.

[0027] The innovation of this invention compared with the prior art lies in:

[0028] I. Foaming during polymerization. First, the key word in foaming during polymerization is "polymerization process." During this period, the monomers in the system transform into polymers, the molecular weight of the polymer increases, and the degree of polymerization increases. The participation of "diphenyl sulfone solvent" is extremely important throughout the entire polymerization process; it needs to be present in the system from beginning to end. When polyetheretherketone (PEEK) is in diphenyl sulfone solvent, the molecular chains are in an extended state, with large intermolecular gaps, which is conducive to gas incorporation. It is precisely because of the presence of diphenyl sulfone solvent that, at high temperatures, diphenyl sulfone forms a homogeneous mixed solution with PEEK, allowing bubbles to disperse, distribute, move, and increase in size, forming a uniform gas-liquid system. The biggest innovation of this invention is foaming during polymerization, thus distinguishing it from foaming in polymer products. Second, foaming occurs during polymerization without removing the diphenyl sulfone solvent throughout the entire polymerization process. After the material system is released from the polymerization reactor, cooled, solidified, and pulverized, it is washed with acetone to remove the diphenyl sulfone solvent. At this point, the internal pores of PEEK have already formed, and the acetone washing process does not affect the shape, size, or number of pores.

[0029] 2. Combine chemical foaming method with physical foaming method and use two-step foaming method.

[0030] The beneficial effects of this invention are as follows:

[0031] (1) This invention discloses a method for preparing polyether ether ketone resin with a microporous structure, which combines the polymerization process of polyether ether ketone resin with the foaming process (foaming directly during the polymerization process). Compared with directly foaming polyether ether ketone material, the polyether ether ketone resin with a microporous structure prepared by this invention has a larger pore density and a larger foaming ratio.

[0032] (2) In this invention, a foaming agent is added during the polymerization reaction of polyether ether ketone resin, combining chemical foaming method with physical foaming method. The polyether ether ketone resin is foamed in two steps, which improves the pore density and foaming ratio of polyether ether ketone resin with microporous structure. Attached Figure Description

[0033] Figure 1 This is a scanning electron microscope image of the polyetheretherketone material with a microporous structure prepared in Example 1 of the present invention.

[0034] Figure 2The infrared transmission spectrum of the polyetheretherketone material with a microporous structure prepared in Example 1 of this invention is shown. Detailed Implementation

[0035] The following non-limiting embodiments are intended to enable those skilled in the art to gain a more comprehensive understanding of the present invention, but do not limit the invention in any way. The following description is merely an exemplary illustration of the scope of protection of the present invention, and those skilled in the art can make various changes and modifications to the invention based on the disclosed content, which should also fall within the scope of protection of the present invention.

[0036] The present invention will be further described below by way of specific embodiments. Unless otherwise specified, all chemical reagents used in the embodiments of the present invention were obtained through conventional commercial means. Unless otherwise specified, all contents mentioned below are mass contents. Unless otherwise specified, it is understood that the process was carried out at room temperature.

[0037] Example 1

[0038] Nitrogen gas was continuously introduced into a 16L sealed high-temperature and high-pressure reactor connected to a water separator, condenser, and stirrer. 6984.6g (32mol) of diphenyl sulfone, 880.8g (8.0mol) of hydroquinone, 1745.6g (8.0mol) of 4,4-difluorobenzophenone, 1017.6g (9.6mol) of sodium carbonate, 44.2g (0.32mol) of potassium carbonate, and 50.67g (0.20mol) of barium azodicarbonate were added. After heating to the point of melting, stirring was started at 80 r / min. The mixture was heated from room temperature until the reaction system stabilized at 180°C and maintained at 180°C for 1 hour. The generated water and gas were separated through a condenser and a separator. The temperature is increased from 180℃ to 245℃, at which point barium azodicarbonate begins to decompose. The valve connecting the reactor to the outside is closed to seal the reactor. The rotation speed is increased to 100 r / min, and the temperature is maintained at 245℃ for 20-30 minutes. Then, the temperature is increased from 245℃ to 310℃, and argon gas is introduced until the pressure inside the reactor reaches 5.0 MPa. The temperature is maintained at 310℃ for 1-2 hours to allow the bubbles to fully dissolve in the homogeneous mixture of diphenyl sulfone and polyether ether ketone, forming a uniform gas-liquid system. When the torque value of the stirrer's torque sensor reaches the target value N1, the valve is opened to quickly depressurize the mixture. The mixture inside the reactor is quickly poured onto a smooth stainless steel plate to cool. The depressurization time is controlled at 5-10 seconds, and the discharge time is controlled at 20-40 seconds. The cooled material is crushed, washed 5 times with acetone, and then washed 5 times with deionized water. It is then placed in a stainless steel tray and dried in an oven at 150℃ for 8 hours to obtain a foamed polyether ether ketone product with a microporous structure.

[0039] Example 2

[0040] Nitrogen gas was continuously introduced into a 16L sealed high-temperature and high-pressure reactor connected to a water separator, condenser, and stirrer. 6984.6g (32mol) of diphenyl sulfone, 880.8g (8.0mol) of hydroquinone, 1745.6g (8.0mol) of 4,4-difluorobenzophenone, 1017.6g (9.6mol) of sodium carbonate, 44.2g (0.32mol) of potassium carbonate, and 68.78g (0.30mol) of p-toluenesulfonamide were added. After heating to the point of melting, stirring was started at 80 r / min. The mixture was heated from room temperature until the reaction system stabilized at 180°C and maintained at 180°C for 1 hour. The generated water and gas were separated through a condenser and a separator. The temperature is raised from 180℃ to 220℃, at which point p-toluenesulfonylaminourea begins to decompose. The valve connecting the reactor to the outside is closed to seal the reactor. The rotation speed is increased to 100 r / min, and the temperature is maintained at 220℃ for 20-30 minutes. Then, the temperature is raised from 220℃ to 310℃ while argon gas is introduced until the pressure inside the reactor reaches 5.0 MPa. The temperature is maintained at 310℃ for 1-2 hours to allow the bubbles to fully dissolve in the homogeneous mixture of diphenyl sulfone and polyether ether ketone, forming a uniform gas-liquid system. When the torque sensor value of the stirrer reaches the target value N2, the valve is opened to quickly release the pressure, and the mixture in the reactor is quickly poured onto a smooth stainless steel plate to cool. The pressure release time is controlled at 5-10 seconds, and the discharge time is controlled at 20-40 seconds. The cooled material is pulverized, washed 5 times with acetone, and then washed 5 times with deionized water. It is then placed in a stainless steel tray and dried in an oven at 150℃ for 8 hours to obtain a foamed polyether ether ketone product with a microporous structure.

[0041] Example 3

[0042] Nitrogen gas was continuously introduced into a 16L sealed high-temperature and high-pressure reactor connected to a water separator, condenser, and stirrer. 6984.6g (32mol) of diphenyl sulfone, 880.8g (8.0mol) of hydroquinone, 1745.6g (8.0mol) of 4,4-difluorobenzophenone, 1017.6g (9.6mol) of sodium carbonate, 44.2g (0.32mol) of potassium carbonate, and 133.33g (0.30mol) of 4,4'-oxobis(benzenesulfonamide) were added. After the mixture was heated to the point of melting, stirring was started at 80 r / min. The mixture was heated from room temperature until the reaction system stabilized at 180°C and maintained at 180°C for 1 hour. The generated water and gas were separated through a condenser and a separator. The temperature is increased from 180℃ to 215℃, at which point 4,4'-oxobis(benzenesulfonamide) begins to decompose. The valve connecting the reactor to the outside is closed to seal the reactor. The rotation speed is increased to 120 r / min, and the temperature is maintained at 215℃ for 20-30 minutes. Then, the temperature is increased from 215℃ to 310℃ while argon gas is introduced until the pressure inside the reactor reaches 6.0 MPa. The temperature is maintained at 310℃ for 1-2 hours to allow the bubbles to fully dissolve in the homogeneous mixture of diphenyl sulfone and polyether ether ketone, forming a uniform gas-liquid system. When the torque value of the stirrer's torque sensor reaches the target value N3, the valve is opened to quickly depressurize the mixture and pour it out onto a smooth stainless steel plate to cool. The depressurization time is controlled at 5-10 seconds, and the discharge time is controlled at 20-40 seconds. The cooled material was crushed, washed 5 times with acetone and 5 times with deionized water, and then placed in a stainless steel tray and dried in an oven at 150°C for 8 hours to obtain a foamed polyether ether ketone product with a microporous structure.

[0043] Example 4

[0044] Nitrogen gas was continuously introduced into a 16L sealed high-temperature and high-pressure reactor connected to a water separator, condenser, and stirrer. 6984.6g (32mol) of diphenyl sulfone, 880.8g (8.0mol) of hydroquinone, 1745.6g (8.0mol) of 4,4-difluorobenzophenone, 1017.6g (9.6mol) of sodium carbonate, 44.2g (0.32mol) of potassium carbonate, and 85.58g (0.50mol) of trihydrazine were added. After heating to the point of melting, stirring was started at 80 r / min. The mixture was heated from room temperature until the reaction system stabilized at 180°C and maintained at 180°C for 1 hour. The generated water and gas were separated through a condenser and a separator. The temperature is increased from 180℃ to 265℃, at which point the trihydrazine begins to decompose. The valve connecting the reactor to the outside is closed, ensuring a sealed environment. The rotation speed is increased to 120 r / min, maintaining a constant temperature of 265℃ for 20-30 minutes. Then, the temperature is increased from 265℃ to 310℃ while simultaneously introducing argon gas until the internal pressure reaches 6.0 MPa. This temperature is maintained at 310℃ for 1-2 hours to allow the bubbles to fully dissolve in the homogeneous mixture of diphenyl sulfone and polyether ether ketone, forming a uniform gas-liquid system. When the torque sensor value of the stirrer reaches the target value N4, the valve is opened to quickly release the pressure. The mixture in the reactor is then rapidly poured onto a smooth stainless steel plate for cooling. The pressure release time is controlled within 5-10 seconds, and the discharge time within 20-40 seconds. The cooled material is then pulverized, washed 5 times with acetone and 5 times with deionized water, placed on a stainless steel tray, and dried in an oven at 150℃ for 8 hours to obtain a foamed polyether ether ketone product with a microporous structure.

[0045] Example 5

[0046] Nitrogen gas was continuously introduced into a 16L sealed high-temperature and high-pressure reactor connected to a water separator, condenser, and stirrer. 6984.6g (32mol) of diphenyl sulfone, 880.8g (8.0mol) of hydroquinone, 1745.6g (8.0mol) of 4,4-difluorobenzophenone, 1017.6g (9.6mol) of sodium carbonate, 44.2g (0.32mol) of potassium carbonate, and 101.34g (0.40mol) of barium azodicarbonate were added. After heating to the point of melting, stirring was started at 80 r / min. The mixture was heated from room temperature until the reaction system stabilized at 180°C and maintained at 180°C for 1 hour. The generated water and gas were separated through a condenser and a separator. The temperature is increased from 180℃ to 245℃, at which point the chemical foaming agent begins to decompose. The valve connecting the reactor to the outside is closed to seal the reactor. The rotation speed is increased to 120 r / min, and the temperature is maintained at 245℃ for 20-30 minutes. Then, the temperature is increased from 245℃ to 310℃ while argon gas is introduced until the pressure inside the reactor reaches 10.0 MPa. The temperature is maintained at 310℃ for 1-2 hours to allow the bubbles to fully dissolve in the homogeneous mixture of diphenyl sulfone and polyether ether ketone, forming a uniform gas-liquid system. When the torque sensor of the stirrer reaches the target value N5, the valve is opened to quickly release the pressure, and the mixture in the reactor is quickly poured onto a smooth stainless steel plate to cool. The pressure release time is controlled at 5-10 seconds, and the discharge time is controlled at 20-40 seconds. The cooled material is pulverized, washed 5 times with acetone, and then washed 5 times with deionized water. It is then placed in a stainless steel tray and dried in an oven at 150℃ for 8 hours to obtain a foamed polyether ether ketone product with a microporous structure.

[0047] Example 6

[0048] Nitrogen gas was continuously introduced into a 16L sealed high-temperature and high-pressure reactor connected to a water separator, condenser, and stirrer. 6984.6g (32mol) of diphenyl sulfone, 880.8g (8.0mol) of hydroquinone, 1745.6g (8.0mol) of 4,4-difluorobenzophenone, 1017.6g (9.6mol) of sodium carbonate, 44.2g (0.32mol) of potassium carbonate, and 136.93g (0.8mol) of trihydrazine were added. After heating to the point of melting, stirring was started at 80 r / min. The mixture was heated from room temperature until the reaction system stabilized at 180°C and maintained at 180°C for 1 hour. The generated water and gas were separated through a condenser and a separator. The temperature is raised from 180℃ to 265℃, at which point the chemical foaming agent begins to decompose. The valve connecting the reactor to the outside is closed, keeping the reactor sealed. This temperature is maintained at 265℃ for 20-30 minutes. Then, the temperature is raised from 265℃ to 310℃ while argon gas is introduced until the pressure inside the reactor reaches 6.0 MPa. This temperature is maintained at 310℃ for 1-2 hours to allow the bubbles to fully dissolve in the homogeneous mixture of diphenyl sulfone and polyether ether ketone, forming a uniform gas-liquid system. When the torque sensor of the stirrer reaches the target value N6, the valve is opened to quickly release the pressure. The mixture inside the reactor is then quickly poured onto a smooth stainless steel plate to cool. The pressure release time is controlled within 5-10 seconds, and the discharge time is controlled within 20-40 seconds. The cooled material is then pulverized, washed 5 times with acetone, and then 5 times with deionized water. It is then placed in a stainless steel tray and dried in an oven at 150℃ for 8 hours to obtain a foamed polyether ether ketone product with a microporous structure.

[0049] Example 7

[0050] Nitrogen gas was continuously introduced into a 16L sealed high-temperature and high-pressure reactor connected to a water separator, condenser, and stirrer. 6984.6g (32mol) of diphenyl sulfone, 880.8g (8.0mol) of hydroquinone, 1745.6g (8.0mol) of 4,4-difluorobenzophenone, 1017.6g (9.6mol) of sodium carbonate, 44.2g (0.32mol) of potassium carbonate, and 50.67g (0.20mol) of barium azodicarbonate were added. After heating to the point of melting, stirring was started at 80 r / min. The mixture was heated from room temperature until the reaction system stabilized at 180°C and maintained at 180°C for 1 hour. The generated water and gas were separated through a condenser and a separator. The temperature is increased from 180℃ to 245℃, at which point barium azodicarbonate begins to decompose. The valve connecting the reactor to the outside is closed to seal the reactor. The rotation speed is increased to 100 r / min, and the temperature is maintained at 245℃ for 20-30 minutes. Then, the temperature is increased from 245℃ to 310℃ while argon gas is introduced until the pressure inside the reactor reaches 2.5 MPa. The temperature is maintained at 310℃ for 1-2 hours to allow the bubbles to fully dissolve in the homogeneous mixture of diphenyl sulfone and polyether ether ketone, forming a uniform gas-liquid system. When the torque value of the stirrer's torque sensor reaches the target value N7, the valve is opened to quickly depressurize the mixture. The mixture inside the reactor is quickly poured onto a smooth stainless steel plate to cool. The depressurization time is controlled at 5-10 seconds, and the discharge time is controlled at 20-40 seconds. The cooled material is crushed, washed 5 times with acetone, and then washed 5 times with deionized water. It is then placed in a stainless steel tray and dried in an oven at 150℃ for 8 hours to obtain a foamed polyether ether ketone product with a microporous structure.

[0051] Example 8

[0052] Nitrogen gas was continuously introduced into a 16L sealed high-temperature and high-pressure reactor connected to a water separator, condenser, and stirrer. 6984.6g (32mol) of diphenyl sulfone, 880.8g (8.0mol) of hydroquinone, 1745.6g (8.0mol) of 4,4-difluorobenzophenone, 1017.6g (9.6mol) of sodium carbonate, 44.2g (0.32mol) of potassium carbonate, and 68.78g (0.30mol) of p-toluenesulfonamide were added. After heating to the point of melting, stirring was started at 80 r / min. The mixture was heated from room temperature until the reaction system stabilized at 180°C and maintained at 180°C for 1 hour. The generated water and gas were separated through a condenser and a separator. The temperature is raised from 180℃ to 220℃, at which point p-toluenesulfonamide begins to decompose. The valve connecting the reactor to the outside is closed to seal the reactor. The rotation speed is increased to 100 r / min, and the temperature is maintained at 220℃ for 20-30 minutes. Then, the temperature is raised from 220℃ to 310℃ while argon gas is introduced until the pressure inside the reactor reaches 2.5 MPa. The temperature is maintained at 310℃ for 1-2 hours to allow the bubbles to fully dissolve in the homogeneous mixture of diphenyl sulfone and polyether ether ketone, forming a uniform gas-liquid system. When the torque sensor of the stirrer reaches the target value N8, the valve is opened to quickly release the pressure, and the mixture in the reactor is quickly poured onto a smooth stainless steel plate to cool. The pressure release time is controlled at 5-10 seconds, and the discharge time is controlled at 20-40 seconds. The cooled material is pulverized, washed 5 times with acetone, and then washed 5 times with deionized water. It is then placed in a stainless steel tray and dried in an oven at 150℃ for 8 hours to obtain a foamed polyether ether ketone product with a microporous structure.

[0053] Example 9

[0054] Nitrogen gas was continuously introduced into a 16L sealed high-temperature and high-pressure reactor connected to a water separator, condenser, and stirrer. 6984.6g (32mol) of diphenyl sulfone, 880.8g (8.0mol) of hydroquinone, 1745.6g (8.0mol) of 4,4-difluorobenzophenone, 1017.6g (9.6mol) of sodium carbonate, 44.2g (0.32mol) of potassium carbonate, and 133.33g (0.30mol) of 4,4'-oxobis(benzenesulfonamide) were added. After the mixture was heated to the point of melting, stirring was started at 80 r / min. The mixture was heated from room temperature until the reaction system stabilized at 180°C and maintained at 180°C for 1 hour. The generated water and gas were separated through a condenser and a separator. The temperature is increased from 180℃ to 215℃, at which point 4,4'-oxobis(benzenesulfonamide) begins to decompose. The valve connecting the reactor to the outside is closed to seal the reactor. The rotation speed is increased to 120 r / min, and the temperature is maintained at 215℃ for 20-30 minutes. Then, the temperature is increased from 215℃ to 310℃, and argon gas is introduced until the pressure inside the reactor reaches 3.0 MPa. The temperature is maintained at 310℃ for 1-2 hours to allow the bubbles to fully dissolve in the homogeneous mixture of diphenyl sulfone and polyether ether ketone, forming a uniform gas-liquid system. When the torque value of the stirrer's torque sensor reaches the target value N9, the valve is opened to quickly depressurize the reactor. The mixture inside the reactor is quickly poured onto a smooth stainless steel plate to cool. The depressurization time is controlled at 5-10 seconds, and the discharge time is controlled at 20-40 seconds. The cooled material was crushed, washed 5 times with acetone and 5 times with deionized water, and then placed in a stainless steel tray and dried in an oven at 150°C for 8 hours to obtain a foamed polyether ether ketone product with a microporous structure.

[0055] Example 10

[0056] Nitrogen gas was continuously introduced into a 16L sealed high-temperature and high-pressure reactor connected to a water separator, condenser, and stirrer. 6984.6g (32mol) of diphenyl sulfone, 880.8g (8.0mol) of hydroquinone, 1745.6g (8.0mol) of 4,4-difluorobenzophenone, 1017.6g (9.6mol) of sodium carbonate, 44.2g (0.32mol) of potassium carbonate, and 85.58g (0.50mol) of trihydrazine were added. After heating to the point of melting, stirring was started at 80 r / min. The mixture was heated from room temperature until the reaction system stabilized at 180°C and maintained at 180°C for 1 hour. The generated water and gas were separated through a condenser and a separator. The temperature is increased from 180℃ to 265℃, at which point trihydrazine begins to decompose. The valve connecting the reactor to the outside is closed to seal the reactor. The rotation speed is increased to 120 r / min, and the temperature is maintained at 265℃ for 20-30 minutes. Then, the temperature is increased from 265℃ to 310℃ while argon gas is introduced until the pressure inside the reactor reaches 3.0 MPa. The temperature is maintained at 310℃ for 1-2 hours to allow the bubbles to fully dissolve in the homogeneous mixture of diphenyl sulfone and polyether ether ketone, forming a uniform gas-liquid system. When the torque sensor value of the stirrer reaches the target value N10, the valve is opened to quickly release the pressure, and the mixture in the reactor is quickly poured onto a smooth stainless steel plate to cool. The pressure release time is controlled at 5-10 seconds, and the discharge time is controlled at 20-40 seconds. The cooled material is pulverized, washed 5 times with acetone, and then washed 5 times with deionized water. It is then placed in a stainless steel tray and dried in an oven at 150℃ for 8 hours to obtain a foamed polyether ether ketone product with a microporous structure.

[0057] Example 11

[0058] Nitrogen gas was continuously introduced into a 16L sealed high-temperature and high-pressure reactor connected to a water separator, condenser, and stirrer. 6984.6g (32mol) of diphenyl sulfone, 880.8g (8.0mol) of hydroquinone, 1745.6g (8.0mol) of 4,4-difluorobenzophenone, 1017.6g (9.6mol) of sodium carbonate, 44.2g (0.32mol) of potassium carbonate, and 101.34g (0.40mol) of barium azodicarbonate were added. After heating to the point of melting, stirring was started at 80 r / min. The mixture was heated from room temperature until the reaction system stabilized at 180°C and maintained at 180°C for 1 hour. The generated water and gas were separated through a condenser and a separator. The temperature is increased from 180℃ to 245℃, at which point the chemical foaming agent begins to decompose. The valve connecting the reactor to the outside is closed to seal the reactor. The rotation speed is increased to 120 r / min, and the temperature is maintained at 245℃ for 20-30 minutes. Then, the temperature is increased from 245℃ to 310℃ while argon gas is introduced until the pressure inside the reactor reaches 5.0 MPa. The temperature is maintained at 310℃ for 1-2 hours to allow the bubbles to fully dissolve in the homogeneous mixture of diphenyl sulfone and polyether ether ketone, forming a uniform gas-liquid system. When the torque sensor of the stirrer reaches the target value N11, the valve is opened to quickly release the pressure, and the mixture in the reactor is quickly poured onto a smooth stainless steel plate to cool. The pressure release time is controlled at 5-10 seconds, and the discharge time is controlled at 20-40 seconds. The cooled material is pulverized, washed 5 times with acetone, and then washed 5 times with deionized water. It is then placed in a stainless steel tray and dried in an oven at 150℃ for 8 hours to obtain a foamed polyether ether ketone product with a microporous structure.

[0059] Comparative Example 1

[0060] The polyether ether ketone material undergoes only chemical foaming during polymerization.

[0061] Nitrogen gas was continuously introduced into a 16L sealed high-temperature and high-pressure reactor connected to a water separator, condenser, and stirrer. 6984.6g (32mol) of diphenyl sulfone, 880.8g (8.0mol) of hydroquinone, 1745.6g (8.0mol) of 4,4-difluorobenzophenone, 1017.6g (9.6mol) of sodium carbonate, 44.2g (0.32mol) of potassium carbonate, and 50.67g (0.20mol) of barium azodicarbonate were added. After heating to the point of melting, stirring was started at 80 r / min. The mixture was heated from room temperature until the reaction system stabilized at 180°C and maintained at 180°C for 1 hour. The generated water and gas were separated through a condenser and a separator. The temperature is increased from 180℃ to 245℃, at which point barium azodicarbonate begins to decompose. The valve connecting the reactor to the outside is closed to seal the reactor. The rotation speed is increased to 100 rpm, and the temperature is maintained at 245℃ for 20-30 minutes. Then, the temperature is increased from 245℃ to 310℃ and maintained at 310℃ for 1-2 hours. When the torque value of the stirrer's torque sensor reaches the target value N12, the valve is opened to quickly release the pressure. The mixture in the reactor is quickly poured onto a smooth stainless steel plate to cool. The pressure release time is controlled at 5-10 seconds, and the discharge time is controlled at 20-40 seconds. The cooled material is pulverized, washed 5 times with acetone, and then washed 5 times with deionized water. It is then placed in a stainless steel tray and dried in an oven at 150℃ for 8 hours to obtain a foamed polyetheretherketone product with a microporous structure.

[0062] Comparative Example 2

[0063] The polyether ether ketone material undergoes only physical foaming during polymerization.

[0064] Nitrogen gas was continuously introduced into a 15L sealed high-temperature and high-pressure reactor connected to a water separator, condenser, and stirrer. 6984.6g (32mol) diphenyl sulfone, 880.8g (8.0mol) hydroquinone, 1745.6g (8.0mol) 4,4-difluorobenzophenone, 1017.6g (9.6mol) sodium carbonate, and 44.2g (0.32mol) potassium carbonate were added. After heating to the point of melting, stirring was started at 80r / min. The reaction system was heated from room temperature until it stabilized at 180℃ and maintained at 180℃ for 1 hour. The generated water and gas were separated through a condenser and a separator. The temperature is increased from 180℃ to 310℃, and the rotation speed is increased to 100 r / min. When the temperature reaches 310℃, the valve connecting the reactor to the outside is closed to seal the reactor. Argon gas is introduced until the internal pressure reaches 5.0 MPa. The reactor is kept at 310℃ for 1-2 hours. When the torque value of the stirrer's torque sensor reaches the target value N13, the valve is opened to quickly release the pressure. The mixture in the reactor is quickly poured onto a smooth stainless steel plate to cool. The pressure release time is controlled at 5-10 seconds, and the discharge time is controlled at 20-40 seconds. The cooled material is pulverized, washed 5 times with acetone, and then washed 5 times with deionized water. It is then placed in a stainless steel tray and dried in an oven at 150℃ for 8 hours to obtain a foamed polyether ether ketone product with a microporous structure.

[0065] Comparative Example 3

[0066] No chemical or physical foaming agents are added during the polymerization reaction. The polyetheretherketone (PEEK) material obtained from polymerization is then foamed by adding both chemical and physical foaming agents.

[0067] Nitrogen gas was continuously introduced into a 16L sealed high-temperature and high-pressure reactor connected to a water separator, condenser, and stirrer. 6984.6g (32mol) diphenyl sulfone, 880.8g (8.0mol) hydroquinone, 1745.6g (8.0mol) 4,4-difluorobenzophenone, 1017.6g (9.6mol) sodium carbonate, and 44.2g (0.32mol) potassium carbonate were added. After the mixture was heated to the point of melting, the stirring was started at 80 r / min. The mixture was heated from room temperature until the reaction system stabilized at 180°C and maintained at 180°C for 1 hour. The generated water and gas were separated through a condenser and a separator. The temperature is increased from 180℃ to 310℃, and the rotation speed is increased to 100 r / min. The mixture is held at 310℃ for 1-2 hours. When the torque value of the stirrer's torque sensor reaches the target value N14, the valve is opened to quickly release the pressure. The mixture in the vessel is then quickly poured onto a smooth stainless steel plate to cool. The pressure release time is controlled at 5-10 seconds, and the discharge time is controlled at 20-40 seconds. The cooled material is then pulverized, washed 5 times with acetone, and then 5 times with deionized water. It is then placed in a stainless steel tray and dried in an oven at 150℃ for 8 hours to obtain the polyetheretherketone (PEEK) product.

[0068] The obtained polyetheretherketone product was put into a 16L sealed high-temperature and high-pressure reactor, and 50.67g (0.20mol) of barium azodicarbonate was added. The stirring was started at 30r / min, and the temperature was raised from room temperature to 245℃. At this time, the barium azodicarbonate began to decompose. The valve connecting the reactor to the outside was closed to keep the reactor sealed. The temperature was maintained at 245℃ for 20-30 minutes. Then the temperature was raised from 245℃ to 310℃. Argon gas was introduced at this time until the gas pressure in the reactor reached 5.0MPa. The temperature was maintained at 310℃ for 1-2 hours. The valve was opened to quickly depressurize, and the mixture in the reactor was poured out onto a smooth stainless steel plate to cool. The depressurization time was controlled at 5-10s, and the discharge time was controlled at 20-40s. The cooled material was crushed, washed three times with acetone and three times with deionized water to remove the decomposition products of barium azodicarbonate. The washed material was then placed in a stainless steel tray and dried in an oven at 150°C for 8 hours to obtain a foamed polyether ether ketone product with a microporous structure.

[0069] Comparative Example 4

[0070] No chemical or physical foaming agents are added during the polymerization reaction. The polyetheretherketone (PEEK) material obtained from polymerization is then foamed by adding a chemical foaming agent.

[0071] Nitrogen gas was continuously introduced into a 15L sealed high-temperature and high-pressure reactor connected to a water separator, condenser, and stirrer. 6984.6g (32mol) diphenyl sulfone, 880.8g (8.0mol) hydroquinone, 1745.6g (8.0mol) 4,4-difluorobenzophenone, 1017.6g (9.6mol) sodium carbonate, and 44.2g (0.32mol) potassium carbonate were added. After heating to the point of melting, stirring was started at 80r / min. The reaction system was heated from room temperature until it stabilized at 180℃ and maintained at 180℃ for 1 hour. The generated water and gas were separated through a condenser and a separator. The temperature is increased from 180℃ to 310℃, and the rotation speed is increased to 100 r / min. The mixture is held at 310℃ for 1-2 hours. When the torque value of the stirrer's torque sensor reaches the target value N15, the valve is opened to quickly release the pressure. The mixture in the vessel is poured onto a smooth stainless steel plate to cool. The pressure release time is controlled at 5-10 seconds, and the discharge time is controlled at 20-40 seconds. The cooled material is then pulverized, washed 5 times with acetone, and then 5 times with deionized water. It is then placed in a stainless steel tray and dried in an oven at 150℃ for 8 hours to obtain the polyetheretherketone (PEEK) product.

[0072] The obtained polyetheretherketone (PEEK) product was placed in a 16L sealed high-temperature and high-pressure reactor, along with 50.67g (0.20mol) of barium azodicarbonate. Stirring was started at 30 rpm, and the mixture was heated from room temperature to 245°C. At this point, the barium azodicarbonate began to decompose. The valve connecting the reactor to the outside was closed, keeping the reactor sealed. The temperature was maintained at 245°C for 20-30 minutes, then increased to 310°C and held at 310°C for 2 hours. The valve was then opened to quickly depressurize the reactor, and the mixture was poured onto a smooth stainless steel plate to cool. The depressurization time was controlled at 5-10 seconds, and the discharge time at 20-40 seconds. The cooled material was pulverized and washed three times with acetone and three times with deionized water to remove the decomposition products of barium azodicarbonate. The washed material was then placed in a stainless steel tray and dried in an oven at 150°C for 8 hours to obtain a foamed PEEK product with a microporous structure.

[0073] Comparative Example 5

[0074] No chemical or physical foaming agents are added during the polymerization process. The polyetheretherketone (PEEK) material obtained from polymerization is then foamed by adding a physical foaming agent.

[0075] Nitrogen gas was continuously introduced into a 16L sealed high-temperature and high-pressure reactor connected to a water separator, condenser, and stirrer. 6984.6g (32mol) diphenyl sulfone, 880.8g (8.0mol) hydroquinone, 1745.6g (8.0mol) 4,4-difluorobenzophenone, 1017.6g (9.6mol) sodium carbonate, and 44.2g (0.32mol) potassium carbonate were added. After the mixture was heated to the point of melting, the stirring was started at 80 r / min. The mixture was heated from room temperature until the reaction system stabilized at 180°C and maintained at 180°C for 1 hour. The generated water and gas were separated through a condenser and a separator. The temperature is increased from 180℃ to 310℃, and the rotation speed is increased to 100 r / min. The mixture is held at 310℃ for 1-2 hours. When the torque value of the stirrer's torque sensor reaches the target value N16, the valve is opened to quickly release the pressure. The mixture in the vessel is poured onto a smooth stainless steel plate to cool. The pressure release time is controlled at 5-10 seconds, and the discharge time is controlled at 20-40 seconds. The cooled material is then pulverized, washed 5 times with acetone, and then 5 times with deionized water. It is then placed on a stainless steel tray and dried in an oven at 150℃ for 8 hours to obtain the polyetheretherketone (PEEK) product.

[0076] The prepared polyetheretherketone (PEEK) product was placed in a 16L sealed high-temperature and high-pressure reactor. Stirring was started at 30 rpm, and the reactor was heated from room temperature to 310°C. The valve connecting the reactor to the outside was closed, ensuring a sealed environment. Argon gas was then introduced until the internal pressure reached 5.0 MPa. The reactor was kept at 310°C for 2 hours. The valve was then opened to quickly depressurize the reactor, and the material was poured onto a smooth stainless steel plate to cool. The depressurization time was controlled at 5-10 seconds, and the discharge time at 20-40 seconds. The cooled material is the foamed PEEK product with a microporous structure.

[0077] The torque values ​​N1-N15 in Examples 1-11 and Comparative Examples 1-5 may be the same or different. Experimenters can make reasonable selections based on specific experimental equipment, test conditions, and conventional operating experience.

[0078] Detection methods

[0079] 1. Melt Flow Index

[0080] The test method is in accordance with the method in standard ISO 1133, with a test temperature of 380℃ and a load of 5kg.

[0081] 2. Crystallinity

[0082] The test method is based on standard ISO 11357, using the DSC method to test crystallinity, with a heating range of 40-400℃ and a heating rate of 10℃ / minute.

[0083] The heat of fusion (ΔH) is obtained by connecting two points on the endothermic peak of fusion that deviate from a relatively straight baseline. m The enthalpy (mJ) of the melt transition is obtained in the integral region as a function of time below the endothermic peak. The mass-normalized heat of fusion (J / g) is calculated by dividing the enthalpy by the sample mass. The crystallinity level (%) is determined by dividing the heat of fusion of the sample by the heat of fusion of the fully crystalline polymer (130 J / g for polyetheretherketone).

[0084] 3. Cell density

[0085] Scanning electron microscopy (SEM) was used to analyze cross-sections of the foamed polymer material to investigate its cell density. The instrument used was a JEOL JSM-6460LV SEM. Cell density is the number of cells per cubic centimeter of foamed sample. The cell density was determined using the Kumar method: the number of cells n (>100) was counted from the SEM images, and the image area A (cm²) was determined. 2 And the magnification factor M, the formula for calculating the cell density N is: f =(nM 2 / A) 3 / 2

[0086] 4. Foaming ratio

[0087] The foaming ratio is the ratio of the volume after foaming to the volume before foaming.

[0088] 5. Closed-pore ratio

[0089] The test method is in accordance with standard ISO4590-2016.

[0090] Table 1

[0091]

[0092] Note: The theoretical gas generation of barium azodicarbonate is calculated as 170 mL / g; the theoretical gas generation of 4,4'-oxobis(benzenesulfonamide) is calculated as 145 mL / g; the theoretical gas generation of trihydrazine is calculated as 247 mL / g; and the theoretical gas generation of p-toluenesulfonamide is calculated as 140 mL / g.

[0093] Table 2

[0094] Melt index (g / 10min) Crystallinity (%) Foaming ratio Closed-cell ratio (%) Example 1 10.8 26.8 8.2 92 Example 2 10.6 26.2 9.5 93 Example 3 18.7 28.9 8.6 95 Example 4 26.2 30.1 9.5 95 Example 5 11.7 27.4 7.6 91 Example 6 7.6 25.7 7.1 93 Example 7 11.2 26.7 5.6 92 Example 8 10.6 26.5 6.3 91 Example 9 10.5 26.6 5.7 92 Example 10 10.3 26.6 6.2 91 Example 11 10.5 26.5 5.1 90 Comparative Example 1 12.5 27.2 1.5 19 Comparative Example 2 22.0 29.5 2.1 31 Comparative Example 3 10.5 26.1 1.0 0 Comparative Example 4 10.2 26.0 1.0 0 Comparative Example 5 10.6 26.7 1.0 0

[0095] The above technical effects demonstrate that polyetheretherketone (PEEK) materials cannot be directly foamed below their melting point, as shown in Comparative Examples 3, 4, and 5. Combining the polymerization and foaming processes of PEEK resin yields PEEK resins with microporous structures exhibiting high pore density and high foaming ratio, as seen in Examples 1-11.

[0096] Compared with Comparative Examples 1 and 2, Examples 1-11 exhibited higher cell density and greater expansion ratio. These technical effects demonstrate that adding both chemical and physical foaming agents during the polymerization process of polyetheretherketone resin, and foaming the resin in a two-step process, improves the cell density and expansion ratio of polyetheretherketone resin with a microporous structure.

[0097] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a polyetheretherketone resin with a microporous structure, characterized in that, Includes the following steps: In the polymerization reaction of polyetheretherketone resin, chemical foaming agents and physical foaming agents are used sequentially for foaming.

2. The preparation method according to claim 1, characterized in that, Includes the following steps: S1. Under the condition of continuous nitrogen gas introduction, add diphenyl sulfone, hydroquinone, 4,4-difluorobenzophenone, sodium carbonate, potassium carbonate and chemical foaming agent to the high-pressure reactor. S2. After heating to the point of melting, start stirring and continue heating to 180°C. Maintain the temperature at 180°C for 1 hour to allow the salt formation reaction to occur. S3. Continue heating to the decomposition temperature of the chemical foaming agent, close the valve connecting the high-pressure reactor to the outside, and keep the high-pressure reactor in a sealed state. At this time, the rotation speed is 80-150 r / min, and the constant temperature duration is 20-60 min. S4. Continue heating to 310℃. While the temperature reaches 310℃, add a physical foaming agent until the gas pressure inside the reactor reaches 2-50MPa. Maintain the temperature at 310℃ for 1-2 hours, and then depressurize using a pressure reducing device for 1-20 seconds.

3. The preparation method according to claim 1 or 2, characterized in that, The chemical foaming agent is selected from at least one of azodicarbonamide, diisopropyl azodicarbonate, barium azodicarbonate, N,N-dinitrospentamethylenetetramine, p-toluenesulfonamide, 4,4'-oxobis(benzenesulfonamide), and trihydrazine.

4. The preparation method according to any one of claims 1-3, characterized in that, The physical foaming agent is selected from at least one of carbon dioxide, helium, neon, and argon.

5. The preparation method according to any one of claims 1-4, characterized in that, The molar ratio of 4,4-difluorobenzophenone to the chemical foaming agent is 100:0.1-12.

6. A polyetheretherketone resin having a microporous structure, characterized in that, The polyetheretherketone resin with a microporous structure is prepared according to the preparation method described in any one of claims 1-5.

Images