Special engineering plastic polyether sulfone microporous foaming material and preparation method thereof

Abstract

This invention relates to a special engineering plastic polyethersulfone microporous foam material and its preparation method, belonging to the field of polymer foaming technology. It solves the problem in existing technologies where high foaming ratio, microporous structure, and excellent mechanical properties cannot be simultaneously achieved when using injection molding technology for macromolecular polyethersulfone materials. The method of this invention includes the following steps: Step 1: Raw material pretreatment; Step 2: Melt blending: Mixing PES substrate, second component, functional filler, crosslinking agent, and cell stabilizer, followed by melt blending, granulation, and drying to obtain granules; Step 3: Injection molding: Injecting the granules into an injection molding machine, adding a composite foaming agent to the injection molding machine, mixing, and injection molding to obtain an injection-molded foam material; Step 4: Curing: Irradiating the injection-molded foam material with X-rays to obtain the special engineering plastic PES microporous foam material.

Description

[0001] This invention relates to the field of polymer foaming technology, and in particular to a special engineering plastic polyethersulfone microporous foaming material and its preparation method. Background Technology

[0002] Microporous foam is a type of foam plastic with an average cell size of less than 10 μm. Its key characteristic is that the internal cells are almost completely closed, independent, and not interconnected. This structure effectively blocks the penetration of water, gas, and heat, while giving the material high compressive strength and low water absorption, making it widely used in the automotive, construction, electronics, and new energy industries. For example, in thermal insulation, microporous foam materials effectively block heat transfer and are commonly used in insulation materials for buildings, automobiles, and aircraft. Polyethersulfone (PES) microporous foam is particularly prominent due to its unique performance advantages. However, with continuous technological advancements, the performance requirements for materials are becoming increasingly stringent. The high density, processing difficulties, and high cost of PES have limited its application in emerging fields. Introducing a cell structure into PES can reduce the material's density / hardness while simultaneously driving its development towards higher performance and multifunctionality, such as thermal insulation and sound insulation. Furthermore, the development of PES foam materials has effectively reduced plastic consumption and increased the cost-effectiveness of products.

[0003] Currently, common PES foaming methods mainly include compression molding chemical foaming and autoclaving physical foaming. However, chemical foaming agents such as azodicarbonamide (AC) generate harmful gases during the foaming process, polluting the environment and making the process more complex and costly. Physical foaming usually requires equipment such as autoclaves, resulting in lower production efficiency and making it difficult to meet the needs of large-scale continuous production.

[0004] Injection foaming technology has attracted widespread attention as an effective means to improve material properties. By introducing nano / micro-scale pore structures, it can significantly reduce material density and improve functionality, thus expanding its application range.

[0005] However, the high viscosity and high processing temperature of PES make foaming difficult. While injection molding technology can reduce PES viscosity by increasing the processing temperature (above 300℃) to achieve foamability, the resulting samples have a very low expansion ratio, only 1-2 times, at such high temperatures. Achieving high expansion ratio (above 3 times), microporous structure (average cell size below 10 micrometers), and excellent mechanical properties (compressive strength ≥ 5.5 MPa) simultaneously during PES foam preparation via injection molding remains a major technical challenge. Summary of the Invention

[0006] Based on the above analysis, the present invention aims to provide a special engineering plastic polyethersulfone microporous foam material and its preparation method, in order to solve the problem that high foaming ratio, microporous structure and excellent mechanical properties cannot be simultaneously achieved when using injection foaming technology for macromolecular polyethersulfone materials.

[0007] The objective of this invention is mainly achieved through the following technical solutions:

[0008] In a first aspect, the present invention provides a special engineering plastic PES microporous foam material, comprising the following components in weight percentage:

[0009]

[0010] The sum of the mass percentages of all components is 100%;

[0011] The second component includes one or more of bis(4-maleimide phenyl) sulfone, 4,4'-di(allyloxy)diphenyl sulfone, bis(4-vinylphenyl) sulfone, and hexafluoroisopropane-containing polyarylether sulfone.

[0012] Optionally, the functional filler includes one or more of cellulose nanofibers, wood fibers, carbon fibers, and polyester fibers.

[0013] Optionally, the crosslinking agent includes one or more of iodonium salts, thionium salts, and ferrocene salts.

[0014] Optionally, the foam stabilizer includes a composite foaming agent comprising a mixture of supercritical nitrogen and supercritical carbon dioxide.

[0015] The foaming material of this invention has an expansion ratio of 3-4.5 times, a closed-cell rate of 90%-96%, an average cell size of 4.3-9.8μm, and a compressive strength of 5.7-8.2MPa.

[0016] Secondly, the present invention provides a method for preparing a special engineering plastic polyethersulfone microporous foam material, which is used to prepare the above-mentioned foam material, comprising the following steps:

[0017] Step 1: Select PES substrate, second component, functional filler, crosslinking agent and cell stabilizer as raw materials according to mass percentage, and pretreat the raw materials;

[0018] Step 2: Melt blending: Mix the pretreated raw materials, melt blend them, then granulate and dry them to obtain granules;

[0019] Step 3: Injection foaming: Inject the granules into the injection molding machine, add the composite foaming agent to the injection molding machine, mix, and inject foaming to obtain the injection molded foam material;

[0020] Step 4: Curing: The injection-molded foam material is irradiated with X-rays to obtain a special engineering plastic PES microporous foam material;

[0021] In step 1, the mass percentage of each component is as follows:

[0022]

[0023] The sum of the mass percentages of all components is 100%;

[0024] The second component includes one or more of bis(4-maleimide phenyl) sulfone, 4,4'-di(allyloxy)diphenyl sulfone, bis(4-vinylphenyl) sulfone, and hexafluoroisopropane-containing polyarylether sulfone.

[0025] Optionally, in step 3, during the injection foaming process, the processing temperature of the injection molding machine is set in zones, wherein the temperature of zone 1 is 190-255℃, the temperature of zone 2 is 200-265℃, and the temperature of zone 3 is 210-285℃.

[0026] Optionally, in step 3, the mixing time is 0.1-5 hours.

[0027] Optionally, in step 4, the radiation used is X-ray, gamma ray, or ultraviolet radiation.

[0028] Optionally, in step 1, the raw material pretreatment includes the following steps: drying and mixing the PES substrate, the second component, the functional filler, the cell stabilizer, and the crosslinking agent.

[0029] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0030] (1) The method of the present invention significantly reduces the high melt viscosity of PES by introducing a specific second component into the PES substrate, thereby improving its processing performance and increasing the foaming ratio. At the same time, it forms good compatibility with the PES matrix resin, providing a good foundation for high-ratio foaming and further improving the foaming ratio. In addition, the aforementioned specific second component can also play a role in radiation crosslinking in the subsequent radiation post-curing process, significantly improving the mechanical properties of PES foam.

[0031] (2) By adding a cell stabilizer, the present invention plays a supporting role in the foaming process, promotes the formation of a uniform microporous structure and improves the closed-cell rate.

[0032] (3) Generally speaking, a high expansion ratio of foam materials will reduce the mechanical properties of the foam materials. In the preparation method of the present invention, by using a radiation curing process after injection foaming, and by selecting a specific second component in the raw materials, the curing process plays a role in radiation crosslinking. Therefore, the mechanical properties of the foam materials will not be significantly reduced at a high expansion ratio, thereby effectively maintaining the compressive strength of the foam materials.

[0033] (4) The functional filler in this invention supports the cell structure and improves the compressive strength of the foamed material; on the other hand, it acts as a cell heterogeneous nucleating agent, increases the cell density, reduces the cell size, and facilitates the formation of a microporous structure.

[0034] (5) The foaming agent of the present invention is a composite foaming agent, wherein the nitrogen has a high nucleation efficiency and a large pore density in the foam, which is beneficial to the formation of microporous foam.

[0035] (6) The specific second component and specific curing process in this invention work synergistically to achieve precise control of the cell structure of the foam material and enhance its multifunctionality, resulting in a foam material with excellent comprehensive performance. Specifically, the foam material of this invention has a high foaming ratio of more than 3 times (e.g., 3-4.5 times), a closed-cell rate of >90% (e.g., 90%-96%), uniform cell size, and an average cell size of <10μm (e.g., 4.3-9.8μm), a compressive strength of ≥5.5MPa (e.g., 5.7-8.2MPa), and a crosslinking degree of ≤10% (e.g., 5%-10%). The special engineering plastic PES microporous high-ratio foam material of this invention has a high foaming ratio, uniform microporous structure, and excellent mechanical properties, while maintaining the inherent chemical corrosion resistance and mechanical strength of the PES matrix resin, thus broadening the application of PES foam materials in cutting-edge fields such as aerospace and transportation.

[0036] (7) The preparation method of this invention is green and efficient, simple to operate, and easy to industrialize. The PES microporous foam material obtained by melt blending and granulation by twin-screw extruder, injection molding and radiation curing not only maintains the advantages of excellent mechanical properties and good processability, but also adopts a composite physical foaming agent, which meets the current social demand for green and low-carbon economy development, reduces the cost of PES foaming, is conducive to the development of special engineering plastic PES microporous foam, broadens its application range, and meets the current social demand for high-performance materials.

[0037] In this invention, the above-described technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of this invention will be set forth in the following description, and some advantages will become apparent from the description or may be learned by practicing the invention. Detailed Implementation

[0038] In a first aspect, the present invention provides a special engineering plastic PES microporous foam material, comprising the following components in weight percentage:

[0039]

[0040]

[0041] The sum of the mass percentages of all components is 100%.

[0042] It should be noted that existing plasticizers cannot play a role in radiation crosslinking in the subsequent post-curing process and cannot form a crosslinked network structure, thus resulting in low mechanical properties of the material.

[0043] The second component in this invention has three main functions: first, it increases the plasticity of PES, improves its processing performance, and increases the foaming ratio; second, it plays a role in radiation crosslinking in the subsequent radiation post-curing process, significantly improving the mechanical properties of PES foam; and third, it forms good compatibility with the PES matrix resin, providing a basic condition for high-ratio foaming and further improving the foaming ratio.

[0044] Specifically, the second component of the present invention includes one or more of bis(4-maleimide phenyl) sulfone, 4,4'-di(allyloxy)diphenyl sulfone, bis(4-vinylphenyl) sulfone, and polyarylether sulfone containing hexafluoroisopropane.

[0045] The second component in this invention has a mass percentage content of 5.0%-40.0% in the raw materials for preparing the foam material, for example, 5.0%, 6.0%, 10.0%, 12.0%, 15.0%, 20.0%, 24.0%, 26.0%, 28.0%, 30.0%, 32.0%, 35.0%, and 40.0%.

[0046] This invention, by selecting a specific second component, can significantly reduce the high melt viscosity of PES, improve its processing performance, and increase the foaming ratio; it also achieves good compatibility with the PES substrate, providing a favorable foundation for high-ratio foaming and further increasing the foaming ratio. Furthermore, this specific second component can also play a role in radiation crosslinking during the subsequent X-ray post-curing process, significantly improving the mechanical properties of the PES foam material.

[0047] The PES substrate in this invention is polyethersulfone with a density of 1.2–1.51 g / cm³. 3 The melt flow index is 8-60 g / 10 min (380℃, 2.16 kg). The addition amount is 49.0%-91.0%, for example, 49%, 53%, 59%, 75%, 80%, 89%, 91%.

[0048] Specifically, the functional filler in this invention includes one or more of cellulose nanofibers (CNF), lignocellulose, carbon fiber, and polyester fiber. These fillers support the cell structure, improving the compressive strength of the foamed material. Furthermore, they act as heterogeneous nucleating agents, increasing cell density and reducing cell size, thus facilitating the formation of a microporous structure. The amount of functional filler added in this invention is 3.0%-8.0%, for example, 3%, 4%, 5%, 6%, 7%, or 8%. The diameter of the functional filler is 5-10 nm, and its length is 0.5-1 μm.

[0049] The crosslinking agent in this invention is one or more of iodonium salts, thiodonium salts, and ferrocene salts. The amount of crosslinking agent added is 0.2%-1.0%, for example, 0.2%, 0.4%, 5%, 0.6%, 0.7%, 0.8%, and 1.0%. The main function of the crosslinking agent is to crosslink PES and the second component, thereby increasing its gel content and improving its mechanical properties.

[0050] Examples of iodonium salts include: 4,4'-dimethyl iodohexafluorophosphate, diphenyl iodonium hexafluoroantimonate, and hydroxyphenyl iodonium salt.

[0051] Examples of thionium salts include: triphenylthionium trifluoromethanesulfonate, triphenylthionium perfluorobutylsulfonate, and triphenylthionium hexafluorophosphate.

[0052] Examples of ferroaluminates include: cyclopentadienyl iron biphenyl salt, cyclopentadienyl iron toluene salt, and cyclopentadienyl iron naphthalene salt.

[0053] The cell stabilizer in this invention is one or a mixture of several of the following: polyether type, siloxane type, fatty acid ester, polyarylether sulfone-polyethylene glycol copolymer, and polytetrafluoroethylene-grafted acrylic acid copolymer. The function of the cell stabilizer is to increase the strength of the cell walls, prevent cell wall rupture, and thus stabilize the cell structure. Its addition amount is 0.3%-1.0%, for example, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, and 1.0%.

[0054] Siloxane-based cell stabilizers include polydimethylsiloxane-ethylene oxide block copolymers, polyether-epoxy co-modified silicone oils, and polyether-polysiloxane copolymers.

[0055] Fatty acid ester cell stabilizers include polyoxyethylene sorbitan stearate, polyoxypropylene styrene phenyl ether stearate, sodium dodecylbenzene sulfonate polyoxyethylene ether laurate, etc.

[0056] The composite foaming agent in this invention comprises a mixture of supercritical nitrogen and supercritical carbon dioxide. The amount of the composite foaming agent added is 0.5%-1.0%, for example, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, or 1.0%.

[0057] Specifically, the volume ratio of supercritical nitrogen to supercritical carbon dioxide in the composite foaming agent is (1-10):1, for example, 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1.

[0058] Secondly, the present invention also provides a method for preparing a special engineering plastic PES microporous foam material, comprising the following steps:

[0059] Step 1: Raw material pretreatment;

[0060] Step 2: Melt blending: Mix the PES base material, the second component, the functional filler, the crosslinking agent, and the cell stabilizer, then place them in an extruder for melt blending, followed by granulation and drying to obtain granules;

[0061] Step 3: Injection foaming: Inject the granules into the injection molding machine, add the composite foaming agent to the injection molding machine, mix, and inject foaming to obtain the injection-molded foam material;

[0062] Step 4: Curing: The injection-molded foam material is irradiated with X-rays to obtain PES microporous foam material, a special engineering plastic.

[0063] In step 1, the raw material pretreatment includes the following steps: drying and mixing the PES substrate, the second component, the functional filler, the cell stabilizer, and the crosslinking agent.

[0064] The drying process includes vacuum drying at 60℃-100℃ for 4-8 hours. Mixing involves adding the components to a high-speed mixer and mixing for 10-20 minutes to ensure thorough and uniform mixing. The high-speed mixer operates at speeds of 60-300 r / min, for example, 60 r / min, 100 r / min, 150 r / min, 200 r / min, 250 r / min, and 300 r / min.

[0065] In step 2, the extruder is a twin-screw extruder. Nitrogen gas is introduced as a protective gas during the extrusion process. The temperature of each section of the extruder is 150-320℃, for example, 150℃, 170℃, 200℃, 230℃, 250℃, 270℃, 290℃, 300℃, 310℃, and 320℃. The screw speed is 50-400 r / min, for example, 50 r / min, 100 r / min, 150 r / min, 200 r / min, 250 r / min, 300 r / min, 350 r / min, and 400 r / min. The blending time is 5-20 min, for example, 5 min, 6 min, 8 min, 10 min, 13 min, 15 min, 17 min, and 20 min.

[0066] In step 2, the drying temperature is 60-90℃, for example, 60℃, 70℃, 80℃, or 90℃. The drying time is 3-8 hours, for example, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, or 8 hours. The particle size of the granules is 0.1-5mm, for example, 0.1mm, 0.3mm, 0.5mm, 0.7mm, 1mm, 2mm, 3mm, 4mm, or 5mm.

[0067] In step 3, during the injection foaming process, the injection molding machine's processing temperature is set in zones. Zone 1 has a temperature range of 190-255℃, for example, 190℃, 200℃, 210℃, 220℃, 230℃, 240℃, 250℃, 255℃. Zone 2 has a temperature range of 200-265℃, for example, 200℃, 210℃, 220℃, 230℃, 240℃, 250℃, 255℃, 260℃, 265℃. Zone 3 has a temperature range of 210-285℃, for example, 210℃, 220℃, 230℃, 240℃, 250℃, 255℃, 260℃, 265℃, 275℃, 280℃, 285℃. Furthermore, the temperature in Zone 3 > Zone 2 > Zone 1. The die head temperature is 210-285℃, for example, 210℃, 220℃, 230℃, 240℃, 250℃, 255℃, 260℃, 265℃, 275℃, 280℃, 285℃.

[0068] In step 3, the mixing time is 0.1-5h, for example, 0.1h, 0.3h, 0.5h, 0.8h, 1h, 1.2h, 1.4h, 1.6h, 2h, 2.5h, 3h, 3.5h, 4h, 4.5h, 5h.

[0069] In step 4, X-rays, gamma rays, or ultraviolet rays are used, with a radiation dose of 20–250 kGy, for example, 20 kGy, 30 kGy, 50 kGy, 80 kGy, 100 kGy, 120 kGy, 140 kGy, 160 kGy, 180 kGy, 200 kGy, 220 kGy, and 250 kGy. The irradiation time is 0.1–3 hours, for example, 0.1 hours, 0.3 hours, 0.5 hours, 1 hour, 1.2 hours, 1.4 hours, 1.8 hours, 2 hours, 2.3 hours, 2.5 hours, and 3 hours. Radiation curing enables the molecular chains of the foam material to form a cross-linked network, further improving the mechanical strength of the PES microporous foam material.

[0070] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the preferred embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the invention.

[0071] In this invention, unless otherwise specified, all methods are conventional methods, and all experimental instruments and reagents are commercially available products that can be purchased through commercial channels.

[0072] Examples 1-5 of the present invention provide a special engineering plastic PES microporous foam material and its preparation method. The raw material composition of the foam materials in Examples 1-5 and Comparative Examples 1-7 is shown in Table 1. The PES substrate was purchased from Fuhai (Dongying) New Material Technology Co., Ltd., model T600.

[0073] Example 1

[0074] Step 1: Raw material pretreatment: Prepare the corresponding mass of PES substrate, second component (bis(4-maleimide phenyl) sulfone), functional filler (carbon fiber), crosslinking agent (4,4'-xylyl iodide hexafluorophosphate), and cell stabilizer (polydimethylsiloxane ethylene oxide block copolymer) according to the proportions in Table 1. Then, place them in a vacuum dryer at 80℃ for 6 hours, and then add them to a high-speed mixer and mix for 15 minutes to ensure that all components are fully mixed and homogeneous, thus obtaining the mixed raw material.

[0075] Step 2: Melt blending: Add the mixed raw materials to the extruder. The temperatures of each section of the extruder are 170℃, 190℃, 210℃, 230℃, 250℃, 260℃, 265℃, and 265℃. The screw speed is 200 r / min, and the blending time is 10 min. After being cut and granulated by a granulator, the mixture is dried (80℃, 4 h) to obtain granules.

[0076] Step 3: Injection foaming: Inject the obtained granules into an injection molding machine (zone 1 temperature is 200℃, zone 2 temperature is 220℃, and zone 3 temperature is 240℃). Add the composite foaming agent (supercritical nitrogen and supercritical carbon dioxide volume ratio is 2:1) into the barrel of the injection molding machine. After thorough mixing (mixing time is 2 hours), injection foaming is performed to obtain the injection-molded foam material.

[0077] Step 4: Curing: The foam material is injection molded using X-ray irradiation (150kGy, 1h) to obtain PES microporous foam material, a special engineering plastic.

[0078] Example 2

[0079] Step 1: Raw material pretreatment: Prepare the corresponding mass of PES substrate, second component (4,4'-di(allyloxy)diphenyl sulfone), functional filler (CNF), crosslinking agent (triphenyl thionium trifluoromethanesulfonate), and cell stabilizer (polyoxyethylene sorbitan stearate) according to the proportions in Table 1. Then, place them in a vacuum dryer at 60℃ for 8 hours, and then add them to a high-speed mixer and mix for 10 minutes to ensure that all components are fully mixed and homogeneous, thus obtaining the mixed raw material.

[0080] Step 2: Melt blending: Add the mixed raw materials to the extruder. The temperatures of each section of the extruder are 150℃, 170℃, 190℃, 210℃, 230℃, 250℃, 260℃, and 260℃. The screw speed is 50 r / min, and the blending time is 20 min. After being cut and granulated by a granulator, the mixture is dried (60℃, 8 h) to obtain granules.

[0081] Step 3: Injection foaming: Inject the obtained granules into an injection molding machine (zone 1 temperature is 190℃, zone 2 temperature is 220℃, and zone 3 temperature is 240℃). Add the composite foaming agent (supercritical nitrogen and supercritical carbon dioxide in a volume ratio of 1:1) into the barrel of the injection molding machine. After thorough mixing (mixing time is 0.5h), injection foaming is performed to obtain the injection-molded foam material.

[0082] Step 4: Curing: The foam material is injection molded using X-ray irradiation (γ-ray, 20kGy, 3h) to obtain special engineering plastic PES microporous foam material.

[0083] Example 3

[0084] Step 1: Raw material pretreatment: Prepare the corresponding mass of PES substrate, second component (bis(4-vinylphenyl) sulfone), functional filler (wood fiber), crosslinking agent (cyclopentadienyl iron biphenyl salt), and cell stabilizer (polyarylene ether sulfone-polyethylene glycol copolymer) according to the proportions in Table 1. Then, place them in a vacuum dryer at 100℃ for 4 hours, and then add them to a high-speed mixer and mix for 20 minutes to ensure that all components are fully mixed and homogeneous, thus obtaining the mixed raw material.

[0085] Step 2: Melt blending: Add the mixed raw materials to the extruder. The temperatures of each section of the extruder are 250℃, 260℃, 270℃, 280℃, 290℃, 300℃, 310℃, and 320℃. The screw speed is 400 r / min, and the blending time is 5 min. After being cut and granulated by a granulator, it is dried (90℃, 3 h) to obtain granules.

[0086] Step 3: Injection foaming: Inject the obtained granules into an injection molding machine (zone 1 temperature is 245℃, zone 2 temperature is 265℃, and zone 3 temperature is 285℃). Add the composite foaming agent (supercritical nitrogen and supercritical carbon dioxide volume ratio of 3:1) into the barrel of the injection molding machine. After thorough mixing (mixing time is 0.5h), injection foaming is performed to obtain the injection-molded foam material.

[0087] Step 4: Curing: The foam material is injection molded by radiation irradiation (ultraviolet light, 250kGy, 0.1h) to obtain PES microporous foam material, a special engineering plastic.

[0088] Example 4

[0089] Step 1: Raw material pretreatment: Prepare the corresponding mass of PES substrate, second component (containing hexafluoroisopropane polyarylether sulfone), functional filler (polyester fiber), crosslinking agent (hydroxyphenyl iodonium salt), and cell stabilizer (polytetrafluoroethylene-grafted acrylic acid copolymer) according to the proportions in Table 1. Then, place them in a vacuum dryer at 80℃ for 6 hours, and then add them to a high-speed mixer and mix for 15 minutes to ensure that all components are fully mixed and uniform, thus obtaining the mixed raw material.

[0090] Step 2: Melt blending: Add the mixed raw materials to the extruder. The temperatures of each section of the extruder are 180℃, 200℃, 220℃, 240℃, 260℃, 270℃, 280℃, and 285℃. The screw speed is 200 r / min, and the blending time is 10 min. After being cut and granulated by the granulator, it is dried (70℃, 5 h) to obtain granules.

[0091] Step 3: Injection foaming: Inject the obtained granules into an injection molding machine (zone 1 temperature is 210℃, zone 2 temperature is 230℃, and zone 3 temperature is 250℃). Add the composite foaming agent (supercritical nitrogen and supercritical carbon dioxide volume ratio is 2:1) into the barrel of the injection molding machine. After thorough mixing (mixing time is 2 hours), injection foaming is performed to obtain the injection-molded foam material.

[0092] Step 4: Curing: The foam material is injection molded using X-ray irradiation (70kGy, 2h) to obtain PES microporous foam material, a special engineering plastic.

[0093] Example 5

[0094] Step 1: Raw material pretreatment: Prepare the corresponding mass of PES substrate, second component (bis(4-vinylphenyl)sulfone), functional filler (carbon fiber), crosslinking agent (triphenyl thionyl hexafluorophosphate), and cell stabilizer (polyoxypropylene styrene phenyl ether stearate) according to the proportions in Table 1. Then place them at 80°C and add them to a high-speed mixer and mix for 15 minutes to ensure that all components are fully mixed and homogeneous, thus obtaining the mixed raw material.

[0095] Step 2: Melt blending: Add the mixed raw materials to the extruder. The temperatures of each section of the extruder are 190℃, 210℃, 230℃, 250℃, 270℃, 290℃, 300℃, and 305℃. The screw speed is 300 r / min, and the blending time is 8 min. After being cut and granulated by a granulator, the mixture is dried (75℃, 4.5 h) to obtain granules.

[0096] Step 3: Injection foaming: Inject the obtained granules into an injection molding machine (zone 1 temperature is 220℃, zone 2 temperature is 240℃, and zone 3 temperature is 260℃). Add the composite foaming agent (supercritical nitrogen and supercritical carbon dioxide volume ratio of 2:1) into the barrel of the injection molding machine. After thorough mixing (mixing time is 2 hours), injection foaming is performed to obtain the injection-molded foam material.

[0097] Step 4: Curing: The foam material is injection molded by radiation irradiation (γ-ray, 200kGy, 0.8h) to obtain special engineering plastic PES microporous foam material.

[0098] Table 1 Chemical composition, wt%

[0099]

[0100]

[0101] The inventors conducted extensive experimental research during the research process, and some poorly performing solutions are now presented as comparative examples.

[0102] Comparative Example 1

[0103] This comparative example is basically the same as Example 1, except that no second component is added.

[0104] Comparative Example 2

[0105] This comparative example is basically the same as Example 1, except that the amount of functional filler added is too small, only 2%.

[0106] Comparative Example 2-1

[0107] This comparative example is basically the same as Example 1, except that the amount of functional filler added is too much, at 9%.

[0108] Comparative Example 3

[0109] This comparative example is basically the same as Example 1, except that it does not undergo radiation curing.

[0110] Comparative Example 4

[0111] This comparative example is basically the same as Example 1, except that the second component uses an existing plasticizer—perfluoropolyether (PFPE).

[0112] Comparative Example 5

[0113] This comparative example is basically the same as Example 1, except that the foaming agent is a single foaming agent: supercritical carbon dioxide.

[0114] Comparative Example 6

[0115] This comparative example is basically the same as Example 1, except that the mass percentage of the second component is 42%.

[0116] Comparative Example 7

[0117] This comparative example is basically the same as Example 1, except that the mass percentage of the second component is 3%.

[0118] Performance tests: The foam density was measured using a density balance; the uncrosslinked portions of the material were dissolved using a solvent via the Soxhlet reflux method, while the crosslinked portions, due to their chemical structural stability, remained undissolved. The degree of crosslinking was calculated by comparing the mass before and after dissolution. The mechanical properties of the foam were tested using a universal testing machine.

[0119] The main performance test results of the foam materials in the examples and comparative examples are shown in Table 2.

[0120] Table 2. Test results of the foamed products obtained in the examples and comparative examples.

[0121]

[0122] As shown in Table 2, the foam material of the present invention has an expansion ratio of 3-4.5 times, a closed-cell ratio of 90%-96%, an average cell size of 4.3-9.8 μm, a compressive strength of 5.7-8.2 MPa, and a degree of crosslinking of 5%-10%. The foam material of the present invention not only has a high expansion ratio but also excellent mechanical properties, making it a foam material with superior overall performance.

[0123] As can be seen from the data in Table 2 for Example 1 and Comparative Example 1, the foaming ratio of the foam material obtained without the addition of the second component is only 1.3 times, and the cells are irregular. However, the foaming ratio with the addition of the second component is as high as 3.6 times, indicating that the addition of the second component acts as a plasticizer, reducing the viscosity of the PES matrix and thus increasing the foaming ratio.

[0124] Table 2 also shows that when the amount of functional filler added is too small (Comparative Example 2), the average cell size is 11.2 μm, which is not micropores; when the amount added is too large (Comparative Example 2-1), the foaming ratio is too low, only 1.9 times.

[0125] As can be seen from the data in Table 2 for Example 1 and Comparative Example 3, the compressive strength of the foam material obtained without radiation curing is only 3.9 MPa, which is significantly lower than the compressive strength of the foam material obtained with radiation curing (5.9 MPa).

[0126] As can be seen from the data in Example 1 and Comparative Example 4 in Table 2, the foaming ratio using the existing plasticizer is low, only 2.2 times, and the cells are irregular. Furthermore, it cannot play a role in radiation crosslinking in the subsequent radiation post-curing process. Therefore, the compressive strength of the obtained foam material is only 3.5 MPa, and it cannot significantly improve the mechanical properties of the PES foam material.

[0127] As can be seen from the data of Example 1 and Comparative Example 5 in Table 2, when a single foaming agent is used, the average cell size of the foamed material is 12.3 μm, which is not micropores. This proves that using a composite foaming agent of supercritical nitrogen and supercritical carbon dioxide is beneficial to the formation of microporous structures.

[0128] As can be seen from the data in Table 2 of Example 1 and Comparative Example 6, the mass percentage of the added second component was too high, and the average cell size of the resulting foamed material was 14.2 μm, which is not micropores.

[0129] As can be seen from the data in Table 2 of Example 1 and Comparative Example 7, the mass percentage of the added second component is too low, the foaming ratio is only 1.9 times, and the foam cells are irregular.

[0130] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A special engineering plastic polyethersulfone microporous foam material, characterized in that, It contains the following components by mass percentage: PES substrate content: 49.0%-91.0%; The second component is 5.0%-40.0%; Functional fillers: 3.0%-8.0%; Crosslinking agent 0.2%-1.0%; Pore ​​stabilizer 0.3%-1.0%; Composite foaming agent 0.5%-1.0%; The sum of the mass percentages of all components is 100%. The second component includes one or more of bis(4-maleimide phenyl) sulfone, 4,4'-di(allyloxy)diphenyl sulfone, bis(4-vinylphenyl) sulfone, and hexafluoroisopropane-containing polyarylether sulfone; The cell stabilizer is one or a mixture of several of the following: polyether type, siloxane, fatty acid ester, polyarylether sulfone-polyethylene glycol copolymer, and polytetrafluoroethylene-grafted acrylic acid copolymer. The crosslinking agent includes one or more of iodonium salts, thionium salts, and ferrocene salts; The composite foaming agent comprises a mixture of supercritical nitrogen and supercritical carbon dioxide; The foaming material has an expansion ratio of 3-4.5 times, a closed-cell rate of 90%-96%, an average cell size of 4.3-9.8μm, and a compressive strength of 5.7-8.2MPa.

2. The foamed material according to claim 1, characterized in that, The functional filler includes one or more of cellulose nanofibers, wood fibers, carbon fibers, and polyester fibers.

3. A method for preparing a special engineering plastic polyethersulfone microporous foam material, used to prepare the foam material according to claim 1 or 2, characterized in that, Includes the following steps: Step 1: Select PES substrate, second component, functional filler, crosslinking agent and cell stabilizer as raw materials according to mass percentage, and pretreat the raw materials; Step 2: Melt blending: The pretreated raw materials are mixed, melt blended, then granulated and dried to obtain granules; Step 3: Injection foaming: Inject the granules into the injection molding machine, add the composite foaming agent to the injection molding machine, mix, and inject foaming to obtain the injection molded foam material; Step 4: Curing: The injection-molded foam material is subjected to X-ray irradiation to obtain a special engineering plastic PES microporous foam material.

4. The method according to claim 3, characterized in that, In step 3, during the injection... During the injection molding process, the processing temperature of the injection molding machine is set in zones: Zone 1 is 190-255℃, Zone 2 is 200-265℃, and Zone 3 is 210-285℃.

5. The method according to claim 4, characterized in that, In step 3, the mixing time The duration is 0.1-5 hours.

6. The method according to any one of claims 3-5, characterized in that, In step 4, The radiation used is X-ray, gamma ray, or ultraviolet radiation.

7. The method according to claim 6, characterized in that, In step 1, the raw material pretreatment includes the following steps: drying and mixing the PES substrate, the second component, the functional filler, the cell stabilizer, and the crosslinking agent.

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