A polyphenylene sulfide wave-absorbing pyramid, a preparation method and application thereof

Abstract

This invention discloses a polyphenylene sulfide (PPS) microwave absorbing cone, its preparation method, and its application. The method includes processing raw materials, including dehydration, primary reaction (to obtain branched oligomers), chain extension reaction (to obtain PPS polymers), end-capping, slurry filtration, and washing to obtain a PPS powder product. Then, PPS resin raw materials are premixed, melt-granulated, extruded into foamed sheets, and the cone is prepared to obtain the microwave absorbing cone product. After obtaining the PPS material, a co-rotating twin-screw extruder is used to blend and modify the PPS to obtain a functional masterbatch. A supercritical carbon dioxide extrusion method is used to obtain foamed microwave absorbing sheet material, which is then cut, bonded, and assembled into a microwave absorbing cone. This material has an oxygen index of 40%–47%, can withstand a 5kW emission power, and exhibits high oxygen index and high power resistance.

Description

Technical Field

[0001] This invention relates to a microwave absorbing cone and its preparation method, and more particularly to a polyphenylene sulfide microwave absorbing cone, its preparation method, and its application. Background Technology

[0002] The origins of microwave absorbing materials for anechoic chambers can be traced back to the 1930s. In the 1950s, polyurethane foam was widely used in microwave anechoic chambers. It is mainly made of polyurethane as raw material, which is used to prepare loose, porous polyurethane foam. It is then cut into solid carriers according to different design requirements (size, shape), impregnated in a solution mixed with conductive absorbers, combustion aids, antioxidants and other materials, and dried to obtain a broadband microwave absorbing material with good absorption. The preparation cost of this material is low.

[0003] However, existing anechoic chamber absorbing materials have the following drawbacks:

[0004] 1. The processing technology involves many human factors, making it difficult to guarantee product consistency. 2. The product is prone to moisture absorption and is not water-resistant. 3. The service life is relatively short. During service, gravity causes bending, detachment, and powder shedding, which deteriorates the absorption performance. It needs to be replaced every ten years or less, failing to achieve the same lifespan as a microwave anechoic chamber. 4. The material has a low oxygen index. Polyurethane itself has an oxygen index of 17%-18%, classifying it as flammable. After adding combustion accelerants, the final oxygen index of the absorbing material is 26%, classifying it as a B2-level material. 5. The power resistance characteristics are poor. The power resistance of polyurethane absorbing material is less than 1 kW / m², failing to meet the requirements of high-power emission source testing.

[0005] Fire resistance performance is primarily considered from the perspective of flame retardancy. In my country, building materials are classified into four fire resistance levels from highest to lowest: Class A (non-combustible), B1 (flame-retardant), B2 (combustible), and B3 (flammable). Most users require microwave absorbing materials to meet at least Class B2 fire resistance, with some requiring Class B1. The flame retardancy requirements for microwave absorbing materials are mainly based on the oxygen index (GB / T 2406-93 "Test Method for Burning Performance of Plastics—Oxygen Index Method") and the US Navy's three standards (NRL REPORT 8093-Test1, Test2, Test3), with the oxygen index being the primary criterion for flame retardancy.

[0006] Expanded polypropylene (EPP) is a novel microwave absorbing material developed in recent years. High melt strength polypropylene is blended with a conductive absorber to obtain a uniformly dispersed masterbatch. Intermittent foaming technology is used to obtain expanded polypropylene microspheres. Finally, in a molding machine mold, steam heating is used to fuse the microspheres together, and after cooling, the microwave absorbing material product is obtained. This material is clean, has high performance, good water resistance, high pressure and impact strength, and good toughness. Disadvantages include a low oxygen index and a power resistance characteristic of less than 1 kW / m², which does not meet the requirements for high-power emission source testing. Summary of the Invention

[0007] The purpose of this invention is to provide a polyphenylene sulfide absorbing cone, its preparation method and application. The technical problem to be solved is to improve the characteristics of existing anechoic chamber absorbing materials, such as low oxygen index and poor power resistance, and to overcome the shortcomings of the existing technology.

[0008] This invention provides the following solution:

[0009] A method for preparing polyphenylene sulfide, specifically comprising:

[0010] The raw materials are dehydrated to obtain the dehydrated product;

[0011] The dehydrated product was subjected to a primary reaction in a reactor to obtain polyphenylene sulfide oligomers with multiple branches.

[0012] A chain extension reaction was carried out in a reactor to obtain polyphenylene sulfide polymer;

[0013] End-capping treatment is performed on polyphenylene sulfide polymers to remove the chlorine-containing groups from the end groups of the polyphenylene sulfide polymers.

[0014] Furthermore, according to parts by weight, the raw materials include: 100 parts potassium carbonate, 100 parts lithium hydroxide, and 250 parts N-methyl,2-pyrrolidone;

[0015] The raw materials are added to the reaction vessel, stirred, and heated to 190℃-210℃ to perform azeotropic dehydration treatment on the raw materials, thereby obtaining the dehydrated product.

[0016] Furthermore, the primary reaction is as follows: 2-4 dichlorobenzylthiophenol is added to the reaction vessel, and the mixture is heated and stirred to obtain pre-branched polyphenylene sulfide;

[0017] The chain extension reaction is as follows: 100-300 parts of dichlorobenzene, 50 parts of sodium sulfide, and 250 parts of N-methyl,2-pyrrolidone are added to the reaction vessel at one time, and then the temperature is raised to 260℃-280℃ and the reaction is carried out for 5-8 hours to obtain polyphenylene sulfide polymer.

[0018] Further, the end-capping treatment step specifically involves adding 5-10 parts of end-capping agent, wherein the end-capping agent is 4-hydroxythiophenol or thiophenol, the reaction time is 1-3 hours, and the temperature is lowered to room temperature.

[0019] Furthermore, the slurry obtained after end-capping is a mixed slurry containing PPS resin, oligomers, inorganic salts, and solvents. The mixed slurry is filtered and washed with water, and the filtration and washing process is repeated 3-5 times. The material is then placed in a drying equipment at 130℃ and dried for 3-5 hours to obtain a finished PPS powder product.

[0020] A method for preparing a polyphenylene sulfide (PPS) absorbing cone specifically includes:

[0021] Polyphenylene sulfide was synthesized using a polyphenylene sulfide preparation method;

[0022] Premixing: Mix 100 parts of resin raw material, 8-18 parts of absorbent, 0.5-1 part of antioxidant, 0.5-1 part of lubricant, and 10-20 parts of toughening agent evenly according to the mass ratio to obtain a mixture;

[0023] Melt granulation: The mixture is melt granulated to obtain a functional masterbatch in which the absorbent and toughening agent are uniformly dispersed;

[0024] Extruded foamed board: The functional masterbatch is formed using a supercritical carbon dioxide fluid extrusion foaming process;

[0025] Preparation of the pyramid: The shaped sheet material is cut, bonded and cured to obtain the wave-absorbing pyramid.

[0026] Furthermore, it also includes a performance testing step, which includes: microwave absorption performance testing, oxygen index testing, and power factor testing.

[0027] In the premixing step, the absorbent includes carbon nanotubes, graphene, carbon black, and C60;

[0028] In the premixing step, the antioxidants include: tris[2,4-di-tert-butylphenyl] phosphite, N,N'-bis-(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl)hexanediamine, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], and octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate;

[0029] Lubricants include: ethylene bis-stearamide, oxidized polyethylene wax, polypropylene wax, silicone, amide wax, and pentaerythritol stearate;

[0030] Toughening agents include: chopped glass fiber and chopped carbon fiber.

[0031] Furthermore, in the melt granulation step, the extruder temperature is set as follows: Feeding section: 200℃

[0032] ~230℃, other temperature range: 285℃~300℃, screw speed 150rpm-200rpm;

[0033] In the step of extruding foamed sheets, the equipment is heated to the set temperature, and all parts of the extrusion molding equipment are raised to 285℃-300℃. The equipment is preheated for 20min-40min.

[0034] Add the blended functional masterbatch to the hopper, and the single-screw extruder starts conveying the material. At the same time, the melt pump and the shaping machine are turned on.

[0035] When the pressure sensor detects the material, the supercritical carbon dioxide fluid device is turned on, the metering pump is adjusted to a certain value, and supercritical carbon dioxide fluid is input into the single screw extruder.

[0036] After the die is ejected, the speed of the forming machine and the width of the die are gradually adjusted according to the output and thickness of the sheet material.

[0037] A microwave absorbing cone, wherein the microwave absorbing cone is prepared by the aforementioned method for preparing a polyphenylene sulfide microwave absorbing cone.

[0038] Application of polyphenylene sulfide in the preparation method of microwave absorbing cones.

[0039] Compared with the prior art, the present invention has the following advantages:

[0040] This invention first prepares polyphenylene sulfide material, and the final polyphenylene sulfide resin has the following characteristics: weight average molecular weight: 35,000-45,000, molecular weight with bimodal distribution, glass transition temperature greater than 200 degrees Celsius, chlorine content less than 1,000 ppm, and melt strength greater than 0.2 N under the condition of traction speed of 200 mm / s.

[0041] After obtaining polyphenylene sulfide material, polyphenylene sulfide is blended and modified using a co-rotating twin-screw extruder to obtain a functional masterbatch. The foamed microwave absorbing plate material is obtained by supercritical carbon dioxide extrusion. Then, it is cut, bonded, and assembled into a microwave absorbing cone. The oxygen index of this material is 40% to 47%, and it can withstand a 5kW emission power, exhibiting the characteristics of high oxygen index and high power resistance. Attached Figure Description

[0042] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0043] Figure 1 This is a flowchart of the preparation method of polyphenylene sulfide absorbing cone.

[0044] Figure 2 It is a branched oligomer of polyphenylene sulfide obtained from the primary reaction.

[0045] Figure 3 It is a polyphenylene sulfide polymer obtained by chain extension reaction.

[0046] Figure 4 It is a capped polyphenylene sulfide polymer.

[0047] Figure 5 This is a schematic diagram of extrusion molding using an extruder.

[0048] Figure 6 This is one of the schematic diagrams of the splicing of the cones during the fabrication process of the microwave absorbing cone.

[0049] Figure 7 This is the second schematic diagram of the splicing of the cones during the fabrication of the microwave absorbing cone.

[0050] Figure 8 It is a row and column array formed by multiple absorbing cones.

[0051] Figure 9 This refers to the molecular weight distribution of polyphenylene sulfide resin.

[0052] Figure 10 This is a dimension diagram of the wave-absorbing cone.

[0053] Figure 11 This is one of the dimension drawings for the cut part of the wave-absorbing cone.

[0054] Figure 12 This is the second dimension drawing of the cut part of the wave-absorbing cone.

[0055] Figure 13 This is a coordinate graph of the microwave absorption performance of an absorbing cone with a height of 700mm.

[0056] Figure 14 It is a graph showing the changes in radiation power (5kW), test chamber temperature, and cone tip temperature over time.

[0057] Figure 15 This is a coordinate graph showing the molecular weight distribution of 100# polyphenylene sulfide in the comparative example. Detailed Implementation

[0058] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0059] Example 1:

[0060] This embodiment provides a hybrid PPS (polyphenylene sulfide) material using a two-step method. The first step generates branched PPS, followed by chain extension to increase the molecular weight, resulting in a PPS resin with foaming properties. Figure 1 As shown, the specific steps of the method include:

[0061] Step S1: Dehydrate the raw materials to obtain the dehydrated product;

[0062] Step S2: The dehydrated product is subjected to a primary reaction in a reactor to obtain polyphenylene sulfide oligomers with multiple branches.

[0063] Step S3: A chain extension reaction is carried out in a reactor to obtain polyphenylene sulfide polymer;

[0064] Step S4: End-capping treatment is performed on the polyphenylene sulfide polymer to remove the chlorine-containing groups from the end groups of the polyphenylene sulfide polymer.

[0065] The PPS obtained after steps S1 to S4 exhibits the following characteristics: weight-average molecular weight of 35,000-45,000, bimodal molecular distribution, glass transition temperature greater than 200 degrees Celsius, chlorine content less than 1000 ppm, and melt strength greater than 0.2 N at a traction speed of 200 mm / s, demonstrating high melt strength. The branched PPS processed using the above method can be extruded and foamed, while general-purpose PPS materials do not possess this structure and cannot be extruded and foamed.

[0066] Specifically, according to mass parts, the raw materials include: 100 parts potassium carbonate, 100 parts lithium hydroxide, and 250 parts N-methyl,2-pyrrolidone. This step is the primary reaction. The raw materials are added to the reaction vessel, stirred, and heated to 190℃-210℃ to perform azeotropic dehydration treatment, obtaining the dehydrated product. Azeotropic dehydration refers to the process where a substance forms an azeotropic system with water, and at the azeotropic point, the substance evaporates along with the water, and after condensation, it is immiscible with water and separates into layers. Examples include toluene, benzene, etc.

[0067] Specifically, such as Figure 2 As shown, the primary reaction is as follows: 2-4 dichlorobenzylthiophenol is added to the reaction vessel, and the mixture is heated and stirred to obtain pre-branched polyphenylene sulfide.

[0068] like Figure 3 As shown, the chain extension reaction is as follows: 100-300 parts by mass of dichlorobenzene (P-DCB), 50 parts by mass of sodium sulfide, and 250 parts by mass of N-methyl,2-pyrrolidone are added to the reactor in one step, and then the temperature is raised to 260℃-280℃, and the reaction is carried out for 5-8 hours. The chain extension reaction is essentially the extension of the polymer chain based on the product obtained from the primary reaction (reacting the dehydrated product in the reactor) to obtain a polyphenylene sulfide polymer. The molecular formula of the polymer obtained by the chain extension reaction is shown in the accompanying drawings of the specification.

[0069] Specifically, the end-capping process, according to the mass fractions, involves adding 5-10 parts of an end-capping agent, which is 4-hydroxythiophenol or thiophenol, reacting for 1-3 hours, and then cooling to room temperature.

[0070] like Figure 4 As shown, the end groups of PPS are mainly chlorine, and these groups have a significant impact on the melt strength of the material. The presence of these groups should be minimized during the synthesis process. End groups refer to the groups at the ends of polymer molecular chains; for example, the end groups of alkyd resins are hydroxyl or carboxyl groups, and the end groups of polyamides are amino or carboxyl groups. The end group composition of the synthesized polymer depends on the chain formation mode and termination mechanism during polymerization. Besides originating from the monomer itself, end groups are also formed by initiators, molecular weight regulators, chain terminators, or solvents. End groups are the head and tail of the polymer molecular chain; determining the structure and content of end groups allows for the determination of the polymer's average molecular weight, degree of branching, etc.

[0071] Specifically, the slurry obtained after end-capping is a mixed slurry containing PPS resin, oligomers, inorganic salts, and solvents. The mixed slurry is filtered and washed with water, and the process of filtering and washing with water is repeated 3-5 times. Finally, the material is placed in a drying equipment at 130℃ and dried for 3-5 hours to obtain a finished PPS powder product.

[0072] The PPS obtained by the preparation method in this embodiment has the following characteristics: weight-average molecular weight: 35,000-45,000, bimodal molecular distribution, glass transition temperature greater than 200 degrees Celsius, chlorine content less than 1,000 ppm, and melt strength greater than 0.2 N under a traction speed of 200 mm / s, exhibiting high melt strength.

[0073] Example 2:

[0074] This embodiment provides a method for preparing a polyphenylene sulfide (PPS) absorbing cone based on Embodiment 1, specifically including:

[0075] Polyphenylene sulfide was synthesized using the polyphenylene sulfide preparation method described in Example 1.

[0076] Premixing: Mix 100 parts of resin raw material, 8-18 parts of absorbent, 0.5-1 part of antioxidant, 0.5-1 part of lubricant, and 10-20 parts of toughening agent evenly in a high-speed mixer to obtain a mixture;

[0077] Specifically, in the premixing step, the antioxidants include: tris[2,4-di-tert-butylphenyl] phosphite (168), N,N'-bis-(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl)hexamethylenediamine (1098), pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (1010), and octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (1076);

[0078] Lubricants include: ethylene bis-stearamide, oxidized polyethylene wax, polypropylene wax, silicone, amide wax, and pentaerythritol stearate.

[0079] Toughening agents include: chopped glass fiber and chopped carbon fiber.

[0080] The purpose of the premixing step is to mix the various raw materials evenly in advance, in preparation for the subsequent process.

[0081] Melt granulation: The mixture obtained in the premixing step is melt granulated to obtain a functional masterbatch in which the absorbent and toughening agent are uniformly dispersed. In this embodiment, a co-rotating parallel twin-screw extruder is used to melt granulate the mixture obtained in the premixing step. For example, the extruder temperature settings are: feeding section: 200℃~230℃, other temperature sections: 285℃~300℃. Screw speed: 150rpm-200rpm.

[0082] Co-rotating parallel twin-screw extruders are commonly used plastic mixing and dispersing equipment. Their main function is to mix and disperse raw materials evenly. The specific process is as follows: the equipment is heated to 0℃~30℃ above the resin melting point. The resin melts in the melting section. In the mixing section, the other components in the resin are mixed and dispersed evenly through the meshing and shearing of the screw elements, and finally, a composite functional masterbatch is obtained.

[0083] like Figure 5 As shown, the extruded foamed board is formed by using a supercritical carbon dioxide fluid extrusion foaming process to mold the functional masterbatch.

[0084] Specifically, in the step of extruding foamed sheets, the equipment is heated to the set temperature, and all parts of the extrusion molding equipment are raised to 285℃-300℃, and the equipment is preheated for 20min to 40min.

[0085] Add the blended functional masterbatch to the hopper, and the single-screw extruder starts conveying the material. At the same time, the melt pump and the shaping machine are turned on.

[0086] When the pressure sensor detects the material, the supercritical carbon dioxide fluid device is turned on, the metering pump is adjusted to a certain value, and supercritical carbon dioxide fluid is input into the single screw extruder.

[0087] After the die is ejected, the speed of the forming machine and the width of the die are gradually adjusted according to the output and thickness of the sheet material.

[0088] like Figures 6 to 8 The preparation of the cone shown is as follows: the shaped plate is cut, bonded and cured to obtain the wave-absorbing cone.

[0089] Performance testing included microwave absorption performance testing, oxygen index testing, and power factor testing. In the premixing step, the absorbents included carbon nanotubes, graphene, carbon black, and C60, among which:

[0090] Radar absorption performance test: The test method adopts the bow method specified in the Radar Radar Absorbing Material Reflectivity Test Method (GJB 2038A-2011), using a standard pyramidal horn antenna, with the test incident angle being vertical, and the test frequency being 2-18GHz.

[0091] The basis for oxygen index testing: The flame retardant requirements of microwave absorbing materials are mainly based on the oxygen index (GB / T 2406-93 "Test Methods for Burning Performance of Plastics - Oxygen Index Method").

[0092] Power withstand test: The power withstand characteristics of the absorbing cone were tested using the CZWS-4 type microwave absorbing material power withstand test chamber.

[0093] Example 3: This example discloses a microwave absorbing cone. This example is based on and improved upon Examples 1 and 2. First, the raw materials are processed according to Example 1. After dehydration, primary reaction (to obtain branched oligomers), chain extension reaction (to obtain polyphenylene sulfide polymers), end-capping treatment, slurry filtration, and water washing, a PPS powder product is obtained. Then, the PPS resin raw materials are premixed, melt granulated, extruded into foamed boards, and the cone is prepared to obtain the microwave absorbing cone product.

[0094] Example 4: This example discloses the application of polyphenylene sulfide in the preparation method of microwave absorbing cones. In the process of preparing microwave absorbing cones, polyphenylene sulfide is used. Polyphenylene sulfide is blended and modified using a co-rotating twin-screw extruder to obtain a functional masterbatch. The foamed microwave absorbing plate material is obtained by supercritical carbon dioxide extrusion. Then, it is cut, bonded and assembled into a microwave absorbing cone. The oxygen index of this material is 40% to 47%, and it can withstand a 5kW emission power. It has the characteristics of high index and high power resistance.

[0095] Example 5: This example discloses an implementation of a polyphenylene ether preparation method in a specific application scenario:

[0096] As previously mentioned, the low oxygen index and poor power resistance of anechoic chamber absorbing materials are largely due to the low oxygen index and poor power resistance of the resin matrix (polyurethane, polypropylene). For example, polyurethane has an oxygen index of 18%, and polypropylene has an oxygen index of 17.5%, which does not provide combustion support. The table below shows the oxygen index data of existing common plastics. Among them, polyphenylene sulfide has excellent flame retardant properties and belongs to high flame retardant materials. It can achieve a very high flame retardant rating without the addition of combustion accelerants.

[0097] Oxygen Index of Several Typical High-Resolution Materials

[0098] Material Name Oxygen Index / % Polyethylene (PE) 17.5 Polypropylene (PP) 17.5 Polystyrene PS 18.2 Polyurethane (PU) 18 Nylon PA 24 Polyoxymethylene (POM) 15 Polyphenylene sulfide (PPS) 45

[0099] PPS is a thermoplastic crystalline special engineering plastic with a symmetrical molecular structure containing phenyl sulfide groups in its main chain. It has a glass transition temperature of 90℃, a melting point of 286℃, and a processing temperature of about 300℃. It has good melt flowability and low melt viscosity, and has a wide range of applications. It is currently the most widely used and consumed special engineering plastic.

[0100] The microwave absorbing materials used in the anechoic chamber all use foamed polymer materials as the matrix to obtain lightweight microwave absorbing materials. For example, polyurethane is chemically foamed, polypropylene is physically foamed, and in this embodiment, polyphenylene sulfide is a thermoplastic polymer material and is also foamed using a physical foaming method.

[0101] For polymer foaming, two main factors directly affect its foaming efficiency. First, melt strength. If the melt strength is too low, the resin melt cannot support cell formation during foaming, leading to cell rupture and merging, resulting in numerous structural defects. Ultimately, the melt strength of a polymer is determined by the molecular structure of the polymer resin, primarily influenced by molecular weight, molecular weight distribution, and the degree of branching (length and number of branches). Essentially, melt strength depends on the degree of entanglement of the polymer resin molecular chains. Second, the glass transition temperature. A low glass transition temperature is detrimental to polymerization and foaming. The lower the glass transition temperature, the easier it is for the material to crystallize during cooling. The crystalline phase, being the hard region in the polymer matrix, inhibits the solubility of gases in the matrix, hindering foaming. Currently available commercially available polyphenylene sulfide (PPS) materials have low melt strength and low glass transition temperature, making it impossible to prepare materials with high foaming ratios.

[0102] Melt strength is a crucial physical property parameter affecting the foamability of polymers, referring to the polymer's ability to support its own mass in the molten state. Polymer melt strength, sometimes also called melt elasticity, is an approximate measure of polymer elongation viscosity in engineering. It is related to the polymer's molecular weight (MW), molecular weight distribution (MWD), and the amount and length of branches. Ultimately, it depends on the degree of polymer chain entanglement at MelT in the molten state. Higher entanglement results in higher melt strength, so polymer melt strength can be improved through branching or cross-linking.

[0103] The length of polyphenylene sulfide (PPS) molecular chains exhibits polydispersity, and its molecular weight distribution curve follows a normal distribution. The molecular weight distribution (MWD) is typically represented by the ratio of weight-average molecular weight (Mw) to number-average molecular weight (Mn). Bimodal polyphenylene sulfide (PPS) products are characterized by the simultaneous presence of both long and short molecular chains. Their molecular weight distribution curve differs from the normal distribution of conventional PPS, exhibiting two peaks. Existing PPS materials have mature manufacturing processes, but their molecular structures are mostly linear or star-shaped, resulting in low melt strength, low glass transition temperature, and lack of extrusion foaming capabilities.

[0104] The method for preparing the polyphenylene sulfide microwave absorbing cone in this embodiment is as follows:

[0105] Step 1, PPS synthesis:

[0106] 1. Raw material dehydration treatment: The raw materials are divided into the following parts by mass: 100 parts potassium carbonate, 100 parts lithium hydroxide, and 250 parts N-methyl,2-pyrrolidone. They are added to a 100L Hastelloy reactor (GSH-50-100L), stirred at 500 rpm, and heated to 200℃. The raw materials are subjected to azeotropic dehydration treatment for about 1 hour to obtain the dehydrated product.

[0107] 2. Reaction 1:

[0108] Primary reaction: Add 20 parts of 2,4-dichlorothiophenol to the reactor, heat the reactor to 210°C at a rate of 3°C / min, stir at 500 rpm for 1.5 hours to obtain pre-branched PPS, and then cool down to 110°C.

[0109] 3. Reaction 2:

[0110] Chain extension reaction: Add 150 parts of dichlorobenzene (P-DCB), 50 parts of sodium sulfide, and 250 parts of N-methyl,2-pyrrolidone to the reactor at one time, then heat to 270℃ and react for 7 hours.

[0111] 4. Reaction 3:

[0112] End-capping treatment: Add 8 parts by weight of end-capping agent, specifically 4-hydroxythiophenol or thiophenol, react for 2 hours, and then cool to room temperature.

[0113] 5. Post-processing:

[0114] The slurry obtained after the reaction contains PPS resin, oligomers, inorganic salts, solvents, etc. The post-treatment mainly involves filtering and washing the mixture with water, repeating this process 5 times. Finally, the material is placed in a drying equipment at 130℃ and dried for 4 hours to obtain PPS granular (<0.25mm) finished product.

[0115] like Figure 9 As shown, the final PPS characteristics are as follows: weight-average molecular weight: 40,000, molecular weight with bimodal distribution, glass transition temperature: 210 degrees Celsius, chlorine content: 900 ppm. The melt strength was tested using a Rhoeten melt strength tester at a traction speed of 200 mm / s, and the melt strength was 0.3 N.

[0116] Step 2, Premixing:

[0117] Specifically, 100 parts of the above-mentioned resin raw material, 10 parts of absorbent, 0.8 parts of antioxidant, 0.8 parts of lubricant, and 15 parts of toughening agent are mixed evenly in a high-speed mixer (SHR-20L) at a speed of 1000 rpm for 10 minutes.

[0118] Resin raw material: Polyphenylene sulfide synthesized in step one

[0119] Absorbent: Cabot ultra-high conductivity carbon black, BP2000

[0120] Antioxidant: N,N'-bis-(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl)hexamethylenediamine (Irganox1098)

[0121] BASF

[0122] Lubricant: Ethylene bis-stearamide (EBS)

[0123] Toughening agent: Short-cut carbon fiber, 2mm in length, Jiangsu Chuangyu Carbon Fiber Technology Co., Ltd.

[0124] Step 3: Melt Granulation

[0125] The mixture obtained in step 2 was melt-granulated using a co-rotating parallel twin-screw extruder (SHJ-36) to finally obtain a functional masterbatch in which the absorbent and toughening agent are uniformly dispersed.

[0126] The extruder temperature is set as follows: T1: 220℃, T2-T11: 290℃, T12: 300℃.

[0127] Screw speed: 150 rpm

[0128] Feeding rate: 40 kg / h

[0129] Particle size: Φ3mm×3mm

[0130] Step 4: Extruding foamed boards

[0131] The functional masterbatch in step three is foamed using supercritical carbon dioxide fluid extrusion foaming. Specific steps are as follows:

[0132] (1) Heat the equipment to the set temperature. The heating temperatures T1 to T7 are set to 220, 290, 290, 290, 290, 290, and 220, respectively. Preheat the equipment for 30 minutes.

[0133] (2) Add the blended masterbatch to the hopper;

[0134] (3) The single screw extruder starts conveying materials, and at the same time turns on the melt pump (10 rpm) and the shaping machine (10 mm / s);

[0135] (4) When the pressure sensor detects the material, turn on the supercritical carbon dioxide fluid device, adjust the injection pump to 3wt% (percentage of melt weight), and inject supercritical CO2 fluid into the melt.

[0136] (5) After the die is ejected, adjust the opening width of the die according to the thickness of the product (23mm±0.2mm). The density of the foam board is 100g / L.

[0137] Step 5, Prepare the pyramid:

[0138] (1) Cutting: Cutting the extruded sheet, such as Figure 10 As shown, cut according to the size requirements of the pyramid, as follows. Figure 11 and Figure 12 It is cut into multiple pieces as shown.

[0139] (2) Bonding the corner cone: Use high-temperature two-component epoxy resin to bond the cut materials.

[0140] (3) Curing: Place the bonded cones in an oven at 80℃~120℃ for 24 hours to cure. After the resin is completely cured, the wave-absorbing cones are obtained.

[0141] Step 6, Performance Testing: Conduct microwave absorption performance, oxygen index, and power factor tests according to standards.

[0142] like Figure 13 As shown, the microwave absorption performance coordinate diagram of the absorbing cone with a height of 700mm is obtained.

[0143] and Figure 14 As shown, this is a graph showing the changes in the temperature of the test chamber and the temperature of the cone tip over time under a radiation power of 5 kW.

[0144] The oxygen index of the absorbing cone in this embodiment is 45%.

[0145] Comparative Example 1:

[0146] like Figure 15 As shown, in this comparative example, the polyphenylene sulfide resin used is commercially available polyphenylene sulfide resin, specifically manufactured and modeled by Tosoh Corporation of Japan, 100# resin. Subsequent steps 2 to 4 are the same as in Example 5. The final extruded foamed material has a density of 1200 g / L. The material has a low foaming rate and high density, making it unsuitable as a microwave absorbing cone material.

[0147] Test results for 100# polyphenylene sulfide: weight-average molecular weight Mw = 41000, glass transition temperature: 90 degrees Celsius, melt strength of 0.1 N under the conditions of a velocity of 200 mm / s.

[0148] In summary of the proportions and examples, the melt strength of 100# polyphenylene sulfide resin is too low. During the foaming process, the resin melt is difficult to support the formation of cells. In addition, the glass transition temperature of 100# polyphenylene sulfide resin is low, and the resin is prone to crystallization. Gas cannot diffuse in the crystal region, making its foaming process more complicated and the process parameters more difficult to control. As a result, the foaming ratio of the obtained foam material is lower.

[0149] It will be understood by those skilled in the art that, unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. It should also be understood that terms such as those defined in general dictionaries should be understood to have the meaning consistent with their meaning in the context of the prior art, and should not be interpreted in an idealized or overly formal sense unless specifically defined.

[0150] It should be noted that certain terms are used in this specification and claims to refer to specific elements. Those skilled in the art will understand that different manufacturers or producers may use different terms to refer to the same element. This specification and claims do not distinguish elements based on differences in terminology, but rather on differences in function.

[0151] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0152] Furthermore, those skilled in the art will understand that although some embodiments described herein include certain features but not others included in other embodiments, combinations of features from different embodiments are intended to be within the scope of the invention and form different embodiments. For example, any of the embodiments claimed in the claims can be used in any combination of embodiments of the invention.

[0153] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0154] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are feasible for those skilled in the art. If the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0155] All features disclosed in this specification, or steps in all disclosed methods or processes, may be combined in any way, except for mutually exclusive features and / or steps. Any feature disclosed in this specification, unless specifically stated otherwise, may be replaced by other equivalent or similar features. That is, unless specifically stated otherwise, each feature is merely one example of a series of equivalent or similar features. Throughout this specification, the same reference numerals indicate the same elements.

[0156] Those skilled in the art will understand that modules in the device of the embodiments can be adaptively changed and placed in one or more devices different from that embodiment. Modules, units, or components in the embodiments can be combined into a single module, unit, or component, and further, they can be divided into multiple sub-modules, sub-units, or sub-components. Except where at least some of such features and / or processes or units are mutually exclusive, any combination can be used to combine all features disclosed in this specification (including the corresponding claims, abstract, and drawings) and all processes or units of any method or device so disclosed. Unless expressly stated otherwise, each feature disclosed in this specification (including the corresponding claims, abstract, and drawings) may be replaced by an alternative feature that serves the same, equivalent, or similar purpose.

[0157] In this application, the term "exemplary" is used to mean "used as an example, illustration, or description." Any embodiment described as "exemplary" in this application is not necessarily to be construed as being more preferred or advantageous than other embodiments. The following description is provided to enable any person skilled in the art to make and use this application. Details are set forth in the following description for purposes of explanation. It should be understood that those skilled in the art will recognize that this application can be made without using these specific details. In other instances, well-known structures and processes are not described in detail to avoid obscuring the description of this application with unnecessary detail. Therefore, this application is not intended to be limited to the embodiments shown, but is consistent with the broadest scope of the principles and features disclosed in this application.

[0158] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a polyphenylene sulfide (PPS) absorbing cone, characterized in that, Specifically, it includes: The polyphenylene sulfide is used for synthesis; the specific preparation method of the polyphenylene sulfide includes: The raw materials are dehydrated to obtain the dehydrated product; The dehydrated product was subjected to a primary reaction in a reactor to obtain polyphenylene sulfide oligomers with multiple branches. A chain extension reaction was carried out in a reactor to obtain polyphenylene sulfide polymer; End-capping treatment is performed on polyphenylene sulfide polymers to remove the chlorine-containing groups from the end groups of the polyphenylene sulfide polymers; According to the mass fractions, the raw materials include: 100 parts potassium carbonate, 100 parts lithium hydroxide, and 250 parts N-methyl,2-pyrrolidone; The raw materials are added to the reaction vessel, stirred and heated to 190℃-210℃ to perform azeotropic dehydration treatment on the raw materials, and the dehydrated product is obtained. The preparation method of the polyphenylene sulfide absorbing cone includes: Premixing: Mix 100 parts of resin raw material, 8-18 parts of absorbent, 0.5-1 parts of antioxidant, 0.5-1 parts of lubricant, and 10-20 parts of toughening agent evenly according to the mass ratio to obtain a mixture; the weight average molecular weight of polyphenylene sulfide resin is 35,000-45,000, the molecular weight has a bimodal distribution, the glass transition temperature is greater than 200 degrees Celsius, and the melt strength is greater than 0.2N under the condition of traction speed of 200mm / s; Melt granulation: The mixture is melt granulated to obtain a functional masterbatch in which the absorbent and toughening agent are uniformly dispersed; Extruded foamed board: The functional masterbatch is formed using a supercritical carbon dioxide fluid extrusion foaming process; Preparation of the pyramid: The shaped sheet material is cut, bonded and cured to obtain the microwave absorbing pyramid; It also includes a performance testing step, which includes: microwave absorption performance testing, oxygen index testing, and power factor testing. In the premixing step, the absorbent includes carbon nanotubes, graphene, carbon black, and C60; In the premixing step, the antioxidants include: tris[2,4-di-tert-butylphenyl] phosphite, N,N'-bis-(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl)hexanediamine, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], and octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate; Lubricants include: ethylene bis-stearamide, oxidized polyethylene wax, polypropylene wax, silicone, amide wax, and pentaerythritol stearate; Toughening agents include: chopped glass fiber and chopped carbon fiber.

2. The method for preparing the polyphenylene sulfide absorbing cone according to claim 1, characterized in that, The primary reaction is as follows: 2,4-dichlorobenzylthiophenol is added to the reaction vessel, heated and stirred to obtain pre-branched polyphenylene sulfide; The chain extension reaction is as follows: 100-300 parts of dichlorobenzene, 50 parts of sodium sulfide, and 250 parts of N-methyl,2-pyrrolidone are added to the reaction vessel at one time, and then the temperature is raised to 260℃-280℃ and the reaction is carried out for 5-8 hours to obtain polyphenylene sulfide polymer.

3. The method for preparing the polyphenylene sulfide absorbing cone according to claim 1, characterized in that, The specific steps for end-capping treatment are as follows: add 5-10 parts of end-capping agent, wherein the end-capping agent is 4-hydroxythiophenol or thiophenol, react for 1-3 hours, and then cool to room temperature.

4. The method for preparing the polyphenylene sulfide absorbing cone according to claim 3, characterized in that, After end-capping, the resulting slurry is a mixture of PPS resin, oligomers, inorganic salts, and solvents. The mixture is then filtered and washed with water, and this process is repeated 3-5 times. The material is then placed in a 130℃ drying equipment and dried for 3-5 hours to obtain a PPS powder product.

5. The method for preparing the polyphenylene sulfide absorbing cone according to claim 2, characterized in that, The primary reaction is as follows: 20 parts of 2-4 dichlorothiophenol are added to the reaction vessel, the reaction vessel is heated to 210°C at a rate of 3°C / min, and stirred at 500 rpm for 1.5 hours to obtain pre-branched PPS, and then the temperature is lowered to 110°C. The chain extension reaction is specifically carried out by adding 150 parts of dichlorobenzene, 50 parts of sodium sulfide, and 250 parts of N-methyl,2-pyrrolidone to the reaction vessel at one time, and then heating to 270°C and reacting for 7 hours.

6. The method for preparing the polyphenylene sulfide absorbing cone according to claim 1, characterized in that, In the melt granulation step, the extruder temperature settings are as follows: feeding section: 200℃~230℃, other temperature sections: 285℃~300℃, screw speed 150 rpm-200 rpm; In the step of extruding foamed sheets, the equipment is heated to the set temperature, and all parts of the extrusion molding equipment are raised to 285℃-300℃. The equipment is preheated for 20min~40min. Add the blended functional masterbatch to the hopper, and the single-screw extruder starts conveying the material. At the same time, the melt pump and the shaping machine are turned on. When the pressure sensor detects the material, the supercritical carbon dioxide fluid device is turned on, the metering pump is adjusted to a certain value, and supercritical carbon dioxide fluid is input into the single screw extruder. After the die is ejected, the speed of the forming machine and the width of the die are gradually adjusted according to the output and thickness of the sheet material.

7. A wave-absorbing cone, characterized in that, The microwave absorbing cone is prepared using the method described in any one of claims 1 to 6 for preparing a polyphenylene sulfide microwave absorbing cone.

8. The use of a polyphenylene sulfide in the preparation method of the polyphenylene sulfide microwave absorbing cone according to any one of claims 1-6.

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