High-thermal-conductivity low-expansion engineering plastic alloy and preparation method thereof

Abstract

The invention relates to the technical field of engineering plastic alloy materials, in particular to a high-thermal-conductivity low-expansion engineering plastic alloy and a preparation method of the high-thermal-conductivity low-expansion engineering plastic alloy. The compound system is composed of the following components in parts by weight: 50-70 parts of polyphenylene sulfide, 10-30 parts of polyether-ether-ketone and 10-30 parts of polyetherimide. 20 to 30 parts of polyether-ether-ketone; the content of the polyetherimide is 10 to 20 parts. Through a polyphenylene sulfide, polyether-ether-ketone and polyetherimide compounded system, a synergistic high-thermal-conductivity filler and a negative-expansion filler, the bottleneck of the thermal conductivity of a high polymer material is broken through, meanwhile, the anisotropic filler is directionally arranged through electromagnetic field-assisted orientation, shrinkage and warping of a high filler system are inhibited through segmented pressure maintaining, the thermal conductivity is comparable to that of metal aluminum, and the thermal conductivity of the composite material is greatly improved. The density is low, and the requirements of spaceflight light weight and precise heat dissipation are met.

Description

Technical Field

[0001] The invention relates to the technical field of engineering plastic alloy materials, in particular to a high-thermal-conductivity and low-expansion engineering plastic alloy and a preparation method thereof. Background Art

[0002] In fields such as electronics, aerospace, and aviation, equipment generates significant heat during operation, requiring materials with excellent thermal conductivity to dissipate heat quickly while also controlling the thermal expansion coefficient to ensure dimensional stability and reliability. Existing engineering plastics often struggle to simultaneously meet these requirements.

[0003] Based on this, the present invention provides a high thermal conductivity and low expansion engineering plastic alloy and a preparation method thereof to solve the above-mentioned technical problems. Summary of the Invention

[0004] The purpose of the present invention is to provide a high thermal conductivity and low expansion engineering plastic alloy and a preparation method thereof, so as to solve the problems mentioned in the above background technology.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] The present invention provides a high thermal conductivity and low expansion engineering plastic alloy, which is composed of the following raw materials in parts by weight:

[0007] Compound system: 100 parts;

[0008] The compound system is composed of polyphenylene sulfide, polyetheretherketone and polyetherimide, wherein the polyphenylene sulfide is 50-70 parts; the polyetheretherketone is 20-30 parts; and the polyetherimide is 10-20 parts.

[0009] High thermal conductivity filler: 30-150 parts;

[0010] The high thermal conductivity filler is composed of boron nitride, aluminum nitride, aluminum oxide, silicon carbide and graphene, wherein the boron nitride is 10-25 parts; the aluminum nitride is 15-40 parts; the aluminum oxide is 20-60 parts; the silicon carbide is 10-30 parts; and the graphene is 3-10 parts.

[0011] Low expansion filler: 10-80 parts;

[0012] The low expansion filler is composed of fused silica powder, potassium titanate whiskers and carbon fibers, wherein the fused silica powder is 15-50 parts; the potassium titanate whiskers are 5-20 parts; and the carbon fibers are 8-25 parts.

[0013] Interface modifier: 2-15 parts;

[0014] The interface modifier is composed of a silane coupling agent, a maleic anhydride grafted polyolefin elastomer and a terminal hydroxyl hyperbranched polymer, wherein the silane coupling agent is 2-5 parts; the maleic anhydride grafted polyolefin elastomer is 3-8 parts; and the terminal hydroxyl hyperbranched polymer is 1-3 parts.

[0015] The maleic anhydride grafted polyolefin elastomer is a polyolefin elastomer having a density of 0.87 g / cm 3 POE and maleic anhydride elastomer substrate were melt blended in a twin-screw extruder at a mass ratio of 100:1.5, 0.1 wt% dicumyl peroxide was added to initiate free radical grafting, and styrene (1 / 3 of the mass of maleic anhydride) was simultaneously injected as a comonomer to inhibit degradation;

[0016] Functional additives: 0.5-5 parts;

[0017] The functional additive is composed of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, tris(2,4-di-tert-butylphenyl) phosphite and ethylene bisstearamide;

[0018] The pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate: 0.3-1 part; the tris(2,4-di-tert-butylphenyl) phosphite: 0.2-0.5 part; and the ethylene bisstearamide: 0.5-2 parts.

[0019] Preferably, the aluminum nitride is prepared by depositing a nano-silicon oxide layer with a thickness of 50-80 nm at 300°C by plasma enhanced chemical vapor deposition under nitrogen protection on aluminum nitride powder, and then wet-coating with an aminosilane / titanate composite coupling agent ethanol solution, with D50 = 1.5 ± 0.2 μm and a specific surface area of ​​4-6 m 2 / g.

[0020] Preferably, the graphene is prepared by grafting fluorinated hyperbranched poly(aryletherketone) onto graphene in a supercritical CO2 environment at a pressure of 15 MPa and a temperature of 50°C, with 6 layers, a sheet diameter of 25 μm, and a carbon-oxygen ratio of >200:1.

[0021] Preferably, the fused quartz powder is prepared by grafting glycidyl methacrylate and long-chain alkyl silane in a fluidized bed reactor by vapor deposition at 400°C, with a sphericity greater than 0.92, D90 ≤ 3 μm, and a hydroxyl density of 1.8 / nm. 2 .

[0022] Preferably, the carbon fiber is made by heating the fiber at a frequency of 40 kHz and a current density of 0.5 A / dm 2In an ultrasonic-electrochemical combined bath, nanoscale pits were formed by anodic oxidation, and then a polydopamine / nanodiamond composite layer was deposited to obtain a surface groove with a length of 150±20μm, a diameter of 7μm, and a depth of less than 50nm.

[0023] Preferably, the boron nitride is prepared by blending the powder with polyetherimide powder in a high-speed impact mill at a mass ratio of 1:0.3, and then in-situ polymerization initiated by 2.45 GHz, 800 W microwave radiation. The aspect ratio is 100, and the B2O3 content is less than 500 ppm.

[0024] Preferably, the potassium titanate whiskers are prepared by hydrothermally growing a nano-boehmite coating in a subcritical water environment at 200° C. and a pressure of 2 MPa, and then hydrophobizing with silazane in the vapor phase, with an aspect ratio of 40, no free alkali on the surface, and a pH of 7±0.5.

[0025] The present invention also provides a method for preparing a high thermal conductivity and low expansion engineering plastic alloy, comprising the following steps:

[0026] S1. First, pre-treat the filler and modify the surface: place 15-40 parts of aluminum nitride powder in a fluidized bed reactor at a flow rate of 8m 3 / h nitrogen protection by plasma enhanced chemical vapor deposition at 300 ° C with a power of 15 kW and a frequency of 13.56 MHz to deposit a 50-80 nm nano-silicon oxide layer, followed by spray injection of a 20 wt% aminosilane / titanate composite coupling agent ethanol solution, and drying and curing at 120 ° C;

[0027] Simultaneously, 8-25 parts of carbon fiber were loaded into the ultrasound-electrochemical cell, and 40kHz / 2kW ultrasound and 0.5A / dm were started in 0.1mol / L sulfuric acid electrolyte. 2 / 30min anodic oxidation to form nano pits, and then immersed in pH = 8.5, 40℃ polydopamine / nanodiamond plating solution for deposition for 20 minutes;

[0028] S2. Then perform matrix premixing and interfacial activation: 50-70 parts of polyphenylene sulfide, 20-30 parts of polyetheretherketone, and 10-20 parts of polyetherimide were added to a high-speed mixer at 800 rpm and 150 ° C for 5 minutes, and then vacuum dehydration was started at -0.09 MPa and 120 ° C for 30 min to a water content of ≤100 ppm.

[0029] At the same time, 2-5 parts of aminosilane coupling agent and 1-3 parts of terminal hydroxyl hyperbranched polymer are pretreated in a supercritical CO2 reactor at 12MPa and 60°C for 20 minutes to generate a silanized hyperbranched composite agent, which is then dynamically mixed with 3-8 parts of maleic anhydride grafted polyolefin elastomer in a molten state at 180°C for 3 minutes to prepare a composite interface agent;

[0030] S3 is then implemented multi-stage mixing: using a co-rotating twin-screw extruder according to the temperature zone segment operation:

[0031] Zones 1-3 at 290-310°C where the main feed is added to the base plastic;

[0032] In the fourth zone, 10-25 parts of aluminum nitride and 20-60 parts of aluminum oxide are added to the side feed at 300-320°C, and forced dispersion is carried out by a helical tooth block and a counter-rotating element;

[0033] In the fifth zone, pretreated carbon fibers and 5-20 parts of potassium titanate whiskers are added vertically at 290-300°C, and a 45° bevel kneading block is used to induce fiber orientation, with an orientation degree of >85%;

[0034] In zone 6, 3-10 parts of graphene and 10-25 parts of boron nitride are added to the side feed at 280-290°C;

[0035] In zone 7, at 270-280°C, inject the composite interface agent using a liquid injection pump;

[0036] Zone 8: 260-270℃, open -0.1MPa vacuum devolatilization;

[0037] S4. Finally, electromagnetic field-assisted molding is performed: the melt is injected into the mold at 300±5°C. During the mold filling phase, a 0.8T axial 10Hz pulsed magnetic field is applied to orient the potassium titanate whiskers to an orientation angle of less than 15°. The injection pressure is 120-150MPa and the pressure is maintained in stages. The molded part is then transferred to an infrared annealing furnace for step-by-step curing.

[0038] Preferably, in the step S4, when the pressure is maintained in stages, in the first stage of high-pressure maintaining, a high pressure of 80 MPa is applied immediately after the melt fills the mold cavity, and the pressure maintaining time lasts for 5 seconds; in the second stage of low-pressure maintaining, the pressure is reduced to 40 MPa, and the pressure maintaining time is extended to 10 seconds.

[0039] Preferably, the infrared annealing furnace step curing process in step S4 is as follows:

[0040] The substrate was treated at 180°C for 2 hours under a 15 MPa nitrogen atmosphere to allow the matrix resin to fully relax and complete the interfacial coupling reaction.

[0041] Then the temperature was raised to 220°C and kept for 1 hour to promote the crystallization of polyetheretherketone and activate the negative expansion effect of fused silica powder;

[0042] Finally, the temperature was maintained at 250°C for 0.5 hours to strengthen the cross-linking network of polyphenylene sulfide. The cooling rate was controlled to be ≤2°C / min throughout the process and then dropped to 80°C before being taken out of the oven.

[0043] Compared with the prior art, the present invention has the following beneficial effects:

[0044] The application breaks through the bottleneck of the thermal conductivity of high polymer materials by a polyphenylene sulfide, a polyether ether ketone, a polyether imide compound system, and synergistic high thermal conductive fillers and negative expansion fillers, meanwhile, the application also makes anisotropic fillers directional arrangement through electromagnetic field auxiliary orientation, and sectional pressure retention inhibits shrinkage and warping of high filler system, the thermal conductivity is comparable to aluminum, the density is low, and the demand of aerospace lightweight and precise heat dissipation is met. DETAILED DESCRIPTION

[0045] The technical solutions in the embodiments of the application will be clearly and completely described below with reference to the embodiments of the application. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments of the application. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the application.

[0046] I. Material

[0047] The high thermal conductivity and low expansion engineering plastic alloy material in the application is commercially available, wherein, the silane coupling agent is Dynasylan AMMO double amino type silane coupling agent purchased from Yincui Industrial Group; the hydroxyl-terminated type hyperbranched polymer is Hybrane H1500 type hyperbranched polymer purchased from BASF in Germany;

[0048] The application provides a high thermal conductivity and low expansion engineering plastic alloy, which is composed of the following raw materials in parts by weight:

[0049] The compound system is 100 parts.

[0050] The compound system is composed of polyphenylene sulfide, polyether ether ketone and polyether imide, the polyphenylene sulfide is 50-70 parts, the polyether ether ketone is 20-30 parts, and the polyether imide is 10-20 parts.

[0051] The high thermal conductive filler is 30-150 parts.

[0052] The high thermal conductive filler is composed of boron nitride, aluminum nitride, aluminum oxide, silicon carbide and graphene, the boron nitride is 10-25 parts, the aluminum nitride is 15-40 parts, the aluminum oxide is 20-60 parts, the silicon carbide is 10-30 parts, and the graphene is 3-10 parts.

[0053] The low expansion filler is 10-80 parts.

[0054] The low expansion filler is composed of fused quartz powder, potassium titanate whisker and carbon fiber, the fused quartz powder is 15-50 parts, the potassium titanate whisker is 5-20 parts, and the carbon fiber is 8-25 parts.

[0055] The interface modifier is 2-15 parts.

[0056] The interface modifier is composed of a silane coupling agent, a maleic anhydride grafted polyolefin elastomer and a terminal hydroxyl hyperbranched polymer, wherein the silane coupling agent is 2-5 parts; the maleic anhydride grafted polyolefin elastomer is 3-8 parts; and the terminal hydroxyl hyperbranched polymer is 1-3 parts.

[0057] The maleic anhydride grafted polyolefin elastomer is a polyolefin elastomer having a density of 0.87 g / cm 3 POE and maleic anhydride elastomer substrate were melt blended in a twin-screw extruder at a mass ratio of 100:1.5, 0.1 wt% dicumyl peroxide was added to initiate free radical grafting, and styrene (1 / 3 of the mass of maleic anhydride) was simultaneously injected as a comonomer to inhibit degradation;

[0058] Functional additives: 0.5-5 parts;

[0059] The functional additive is composed of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, tris(2,4-di-tert-butylphenyl) phosphite and ethylene bisstearamide;

[0060] The pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate: 0.3-1 part; the tris(2,4-di-tert-butylphenyl) phosphite: 0.2-0.5 part; and the ethylene bisstearamide: 0.5-2 parts.

[0061] Among them, it should be noted that aluminum nitride is prepared by depositing a 50-80 nm thick nano-silicon oxide layer on aluminum nitride powder under nitrogen protection by plasma enhanced chemical vapor deposition at 300 ° C, and then wet-coating with an aminosilane / titanate composite coupling agent ethanol solution. The D50 is 1.5±0.2μm and the specific surface area is 4-6m 2 / g.

[0062] It should also be noted that graphene is prepared by grafting fluorinated hyperbranched polyaryletherketone in a supercritical CO2 environment at a pressure of 15 MPa and a temperature of 50°C. It has 6 layers, a sheet diameter of 25 μm, and a carbon-oxygen ratio of >200:1.

[0063] It should be noted that the fused quartz powder is prepared by segmentally grafting glycidyl methacrylate and long-chain alkyl silane in a fluidized bed reactor by vapor deposition at 400°C. The sphericity is greater than 0.92, D90 ≤ 3 μm, and the hydroxyl density is 1.8 / nm. 2 .

[0064] Among them, it should be noted that carbon fiber is made by mixing fibers at a frequency of 40kHz and a current density of 0.5A / dm 2In an ultrasonic-electrochemical combined bath, nanoscale pits were formed by anodic oxidation, and then a polydopamine / nanodiamond composite layer was deposited to obtain a surface groove with a length of 150±20μm, a diameter of 7μm, and a depth of less than 50nm.

[0065] It should also be noted that boron nitride is prepared by blending the powder with polyetherimide powder in a high-speed impact mill at a mass ratio of 1:0.3, and then in-situ polymerization initiated by 2.45 GHz, 800 W microwave radiation. The aspect ratio is 100 and the B2O3 content is less than 500 ppm.

[0066] Preferably, the potassium titanate whiskers are prepared by hydrothermally growing a nano-boehmite coating in a subcritical water environment at 200° C. and a pressure of 2 MPa, and then hydrophobizing with silazane in the vapor phase, with an aspect ratio of 40, no free alkali on the surface, and a pH of 7±0.5.

[0067] 2. Process:

[0068] The present invention also provides a method for preparing a high thermal conductivity and low expansion engineering plastic alloy, comprising the following steps:

[0069] S1. First, pre-treat the filler and modify the surface: place 15-40 parts of aluminum nitride powder in a fluidized bed reactor at a flow rate of 8m 3 / h nitrogen protection by plasma enhanced chemical vapor deposition at 300 ° C with a power of 15 kW and a frequency of 13.56 MHz to deposit a 50-80 nm nano-silicon oxide layer, followed by spray injection of a 20 wt% aminosilane / titanate composite coupling agent ethanol solution, and drying and curing at 120 ° C;

[0070] Simultaneously, 8-25 parts of carbon fiber were loaded into the ultrasound-electrochemical cell, and 40kHz / 2kW ultrasound and 0.5A / dm were started in 0.1mol / L sulfuric acid electrolyte. 2 / 30min anodic oxidation to form nano pits, and then immersed in pH = 8.5, 40℃ polydopamine / nanodiamond plating solution for deposition for 20 minutes;

[0071] S2. Then perform matrix premixing and interfacial activation: 50-70 parts of polyphenylene sulfide, 20-30 parts of polyetheretherketone, and 10-20 parts of polyetherimide were added to a high-speed mixer at 800 rpm and 150 ° C for 5 minutes, and then vacuum dehydration was started at -0.09 MPa and 120 ° C for 30 min to a water content of ≤100 ppm.

[0072] At the same time, 2-5 parts of aminosilane coupling agent and 1-3 parts of terminal hydroxyl hyperbranched polymer are pretreated in a supercritical CO2 reactor at 12MPa and 60°C for 20 minutes to generate a silanized hyperbranched composite agent, which is then dynamically mixed with 3-8 parts of maleic anhydride grafted polyolefin elastomer in a molten state at 180°C for 3 minutes to prepare a composite interface agent;

[0073] S3 is then implemented multi-stage mixing: using a co-rotating twin-screw extruder according to the temperature zone segment operation:

[0074] Zones 1-3 at 290-310°C where the main feed is added to the base plastic;

[0075] In the fourth zone, 10-25 parts of aluminum nitride and 20-60 parts of aluminum oxide are added to the side feed at 300-320°C, and forced dispersion is carried out by a helical tooth block and a counter-rotating element;

[0076] In the fifth zone, pretreated carbon fibers and 5-20 parts of potassium titanate whiskers are added vertically at 290-300°C, and a 45° bevel kneading block is used to induce fiber orientation, with an orientation degree of >85%;

[0077] In zone 6, 3-10 parts of graphene and 10-25 parts of boron nitride are added to the side feed at 280-290°C;

[0078] In zone 7, at 270-280°C, inject the composite interface agent using a liquid injection pump;

[0079] Zone 8: 260-270℃, open -0.1MPa vacuum devolatilization;

[0080] S4. Finally, electromagnetic field-assisted molding is performed: the melt is injected into the mold at 300±5°C. During the mold filling phase, a 0.8T axial 10Hz pulsed magnetic field is applied to orient the potassium titanate whiskers to an orientation angle of less than 15°. The injection pressure is 120-150MPa and the pressure is maintained in stages. The molded part is then transferred to an infrared annealing furnace for step-by-step curing.

[0081] It should also be noted that in step S4, when the pressure is maintained in stages, the first stage of high-pressure maintaining is to apply a high pressure of 80 MPa immediately after the melt fills the mold cavity, and the holding time lasts for 5 seconds; the second stage of low-pressure maintaining is to reduce the pressure to 40 MPa, and the holding time is extended to 10 seconds.

[0082] It should also be noted that the step curing process of the infrared annealing furnace in step S4 is as follows:

[0083] The substrate was treated at 180°C for 2 hours under a 15 MPa nitrogen atmosphere to allow the matrix resin to fully relax and complete the interfacial coupling reaction.

[0084] Then the temperature was raised to 220°C and kept for 1 hour to promote the crystallization of polyetheretherketone and activate the negative expansion effect of fused silica powder;

[0085] Finally, the temperature was maintained at 250°C for 0.5 hours to strengthen the cross-linking network of polyphenylene sulfide. The cooling rate was controlled to be ≤2°C / min throughout the process and then dropped to 80°C before being taken out of the oven.

[0086] Example 1: In this embodiment, the materials include:

[0087] Polyphenylene sulfide 60 parts, polyether ether ketone 25 parts, polyetherimide 15 parts; aluminum nitride 30 parts, aluminum oxide 40 parts, boron nitride 18 parts, silicon carbide 20 parts, graphene 6 parts; fused quartz powder 35 parts, potassium titanate whisker 12 parts, carbon fiber 15 parts; silane coupling agent 3.5 parts, maleic anhydride grafted POE 5 parts, hyperbranched polymer 2 parts;

[0088] The plastic alloy is prepared according to the following process flow:

[0089] S1. Pretreatment and surface modification of fillers:

[0090] Aluminum nitride treatment:

[0091] 30 parts of aluminum nitride powder were loaded into a fluidized bed reactor, and 8 m 3 / h of nitrogen was introduced to form a fluidized state.

[0092] The plasma enhanced chemical vapor deposition (power 15 kW, frequency 13.56 MHz) was started, and a 50-80 nm nano-silicon oxide layer was deposited at 300°C.

[0093] A 20wt% amino silane / titanate complex coupling agent ethanol solution was sprayed and injected, and dried at 120°C for 30 minutes.

[0094] Carbon fiber treatment:

[0095] 15 parts of chopped carbon fiber (diameter 7 μm) were placed in an ultrasonic-electrochemical combined tank, and 0.1 mol / L sulfuric acid electrolyte was injected.

[0096] The 40 kHz ultrasonic wave (power 2 kW) and 0.5 A / dm 2 Anodic oxidation was carried out for 30 minutes to form nano-pits.

[0097] It was transferred to a polydopamine / nano-diamond composite plating solution (pH=8.5, 40°C), and after 20 minutes of deposition, it was taken out and dried;

[0098] S2. Premixing of matrix and interfacial activation:

[0099] Dehydration of the matrix:

[0100] 60 parts of polyphenylene sulfide, 25 parts of polyether ether ketone, and 15 parts of polyetherimide were added to a high-speed mixer.

[0101] Mixing at 800 rpm for 5 minutes at 150°C, and then vacuum dehydration at -0.09 MPa for 30 minutes (water content ≤100 ppm).

[0102] Preparation of composite interfacial agent:

[0103] 3.5 parts of aminosilane coupling agent and 2 parts of terminal hydroxyl hyperbranched polymer were placed in a supercritical CO2 reactor (12 MPa, 60°C) and treated for 20 minutes to generate a silanized hyperbranched composite agent.

[0104] 5 parts of maleic anhydride grafted POE (grafting rate 1.0%) were melted to 180°C and mixed with the compounding agent in a dynamic mixer for 500s -1 Shear mix for 3 minutes.

[0105] S3. Multi-stage mixing:

[0106] The working process was implemented by a co-rotating twin-screw extruder (L / D = 48, screw diameter 45 mm, speed 300 rpm) according to the parameters in Table 1;

[0107]

[0108]

[0109] S4. Electromagnetic field assisted molding and post-curing

[0110] Injection molding:

[0111] The melt was injected into the mold at 300°C (mold temperature 140°C), and a 0.8T axial pulsed magnetic field (frequency 10 Hz) was applied during the mold filling stage.

[0112] Segmented pressure keeping:

[0113] The first stage: 80MPa high pressure holding for 5 seconds (to compensate for shrinkage and compact the filler);

[0114] The second stage: 40MPa low pressure holding for 10 seconds (stress release and size stabilization).

[0115] Step curing:

[0116] The molded parts are transferred to the infrared annealing furnace under a 15MPa nitrogen environment:

[0117] Constant temperature at 180 °C for 2 h resulted in activation of interfacial coupling;

[0118] Heating at 220°C for 1 hour promotes the crystallization of PEEK;

[0119] Heating at 250°C for 0.5 h resulted in enhanced cross-linking of the polyphenylene sulfide.

[0120] Cool to 80℃ at a rate of ≤2℃ / min and take out of the oven.

[0121] Example 2: In this example, polyphenylene sulfide is 50 parts, polyetheretherketone is 30 parts, and polyetherimide is 20 parts; the high thermal conductivity filler includes 10 parts of boron nitride, 15 parts of aluminum nitride, 60 parts of aluminum oxide, and 3 parts of graphene; the low expansion filler includes 15 parts of fused silica powder and 25 parts of carbon fiber; other process parameters are the same as those in Example 1;

[0122] Example 3. In this example, polyphenylene sulfide is 70 parts, polyetheretherketone is 20 parts, and polyetherimide is 10 parts; the high thermal conductivity filler includes 25 parts of boron nitride, 40 parts of aluminum nitride, 20 parts of aluminum oxide, and 10 parts of graphene; the low expansion filler includes 50 parts of fused silica powder and 8 parts of carbon fiber; other process parameters are the same as those in Example 1;

[0123] Example 4: In this example, the material composition is exactly the same as that of Example 1, but the staged pressure holding parameters are adjusted as follows: 60 MPa high pressure holding for 8 seconds in the first stage, and 30 MPa low pressure holding for 15 seconds in the second stage; other process parameters are the same as those of Example 1;

[0124] Example 5: In this example, the material composition is exactly the same as that of Example 1, but the pulsed magnetic field assist is eliminated during injection molding; the other process parameters are the same as those of Example 1;

[0125] Comparative Example 1: In this comparative example, polyphenylene sulfide is 45 parts, polyetheretherketone is 35 parts, graphene is 12 parts, and fused silica powder is 5 parts; other components and process parameters are the same as those in Example 1;

[0126] Comparative Example 2: In this comparative example, the amount of polyphenylene sulfide is 75 parts, and the amount of fused silica powder is 55 parts; the other components and process parameters are the same as those in Example 1;

[0127] Comparative Example 3: In this comparative example, the material components are the same as those in Example 1, but all the interface modifiers are eliminated; the other process parameters are the same as those in Example 1;

[0128] The process parameters of the embodiment are shown in Table 2:

[0129] Table 2: Example material composition (mass parts)

[0130]

[0131]

[0132] The standard process is: segmented pressure holding 80MPa×5s+40MPa×10s; electromagnetic field assisted molding (0.8T / 10Hz)

[0133] Example 4: Pressure adjustment: 60 MPa×8s+30 MPa×15s

[0134] Example 5: Canceling the pulsed magnetic field

[0135] The process parameters of the comparative example are shown in Table 3:

[0136] Table 3: Comparative Example Material Components (Parts by Mass)

[0137]

[0138]

[0139] 3. Performance test:

[0140] Samples were prepared according to Examples 1-5 and Comparative Examples 1-3, and samples using a conventional PPS process were also prepared, and the following performance tests were performed:

[0141] Performance testing includes:

[0142] a. Thermal conductivity: laser flash method (ASTM E1461, 25°C);

[0143] b. Thermal expansion coefficient: thermomechanical analyzer (TMA, -40 ~ 180 ° C);

[0144] c. Flexural strength: three-point bending test (ISO 178, span 64 mm);

[0145] d. Impact strength: Izod notched impact (ISO 180, notch depth 2 mm);

[0146] The performance data of the samples in the embodiment are shown in Table 4:

[0147] Table 4: Example performance data

[0148] Performance indicators Example 1 Example 2 Example 3 Example 4 Example 5 Thermal conductivity (W / m·K) 16.8 13.5 15.2 14.1 12.3 <![CDATA[热膨胀系数(×10 -6 / K)]]> 7.2 9.8 8.5 8.9 10.6 Flexural strength (MPa) 186 152 175 168 142 <![CDATA[冲击强度(kJ / m 2 )]]> 24.5 19.8 22.1 20.3 17.6 Heat deformation temperature (℃) 278 265 272 268 253

[0149] The performance data of the comparative example and traditional PPS samples are shown in Table 5:

[0150] Table 5: Comparative Example Performance Data

[0151] Performance indicators Comparative Example 1 Comparative Example 2 Comparative Example 3 Traditional PPS* Thermal conductivity (W / m·K) 9.3 11.7 6.2 0.8 <![CDATA[热膨胀系数(×10 -6 / K)]]> 18.5 12.8 35.2 55 Flexural strength (MPa) 125 138 92 160 <![CDATA[冲击强度(kJ / m 2 )]]> 10.2 14.5 6.8 8.5 Heat deformation temperature (℃) 240 258 220 260

[0152] Among them, it should be noted that traditional PPS* refers to unmodified polyphenylene sulfide with 40% glass fiber added;

[0153] 4. Data Analysis and Conclusions

[0154] Regarding the amount of polyphenylene sulfide used, the matrix strength of Comparative Example 1 was insufficient at 45 parts, resulting in the bending strength dropping to 125 MPa, which was 33% lower than that of Example 1. In Comparative Example 2, the excess amount of PPS at 75 parts resulted in the CTE rising to 12.8×10 -6 / K, while Example 1 is only 7.2; At the same time, regarding the impact of filler overlimit, including Comparative Example 1 with 12 parts of graphene, the stacking of layers makes the thermal conductivity only 9.3W / m·K, while Example 1 is 16.8; Comparative Example 2 with 55 parts of fused quartz powder, the interface debonding causes the impact strength to drop by 37%; Regarding the core verification of the interface agent, including Comparative Example 3 without interface agent, the CTE is as high as 35.2×10 -6 / K, impact strength less than 7kJ / m 2 In summary, it can be verified that the composition range of the material of the present invention achieves a balance between thermal conductivity, expansion, and mechanical properties, breaking through the performance contradictions of traditional engineering plastics.

[0155] In Example 1 of the present invention, 60 parts of polyphenylene sulfide are used to ensure heat resistance (HDT 278°C); 25 parts of polyetheretherketone are used to balance mechanical strength (bending 186 MPa); 15 parts of polyetherimide are used to achieve a melt flow rate of 38 g / 10 min; and 6 parts of graphene are used to build an efficient thermal conductive network (>15 W / m·K) with a resistivity of >10 15 Ω·cm; 35 parts of fused silica powder + 15 parts of carbon fiber, CTE is reduced to 7.2×10 -6 / K, the material components are balanced; and the pulsed magnetic field makes the orientation angle of potassium titanate whiskers less than 15°, the axial CTE is reduced by 22%, the segmented pressure holding controls the shrinkage rate ≤0.02% (the aerospace standard requires ≤0.05%), the process efficiency is significantly improved, and the final performance is at the optimal parameters. Therefore, Example 1 is the best embodiment of the present invention.

[0156] Finally, the comparative advantages of Example 1 of the present invention over traditional PPS* engineering plastics are shown in Table 6:

[0157] Table 6: Comparative parameters of the sample in Example 1 compared with traditional PPS* engineering plastics

[0158] performance Example 1 Traditional PPS (40% glass fiber) Improvement rate Thermal conductivity 16.8 0.8 2000％ Coefficient of thermal expansion 7.2 55 -87％ Impact strength 24.5 8.5 188％

[0159] In summary, the present invention breaks through the bottleneck of thermal conductivity of polymer materials by using a compound system of polyphenylene sulfide, polyetheretherketone, and polyetherimide, in conjunction with high thermal conductivity fillers and negative expansion fillers. At the same time, the present invention also uses electromagnetic field-assisted orientation to directional arrange anisotropic fillers, and segmented pressure maintenance to suppress shrinkage and warping of the high-filler system. The thermal conductivity is comparable to that of metallic aluminum, and the density is low, meeting the lightweight and precise heat dissipation needs of aerospace.

[0160] Throughout this specification, references to terms such as "one embodiment," "example," or "specific example" indicate that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, schematic representations of these 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 any one or more embodiments or examples.

[0161] The preferred embodiments of the present invention disclosed above are intended only to help illustrate the present invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the present invention to the specific embodiments described. Obviously, many modifications and variations are possible based on the content of this specification. These embodiments are selected and described in detail in this specification to better explain the principles and practical applications of the present invention, thereby enabling those skilled in the art to better understand and utilize the present invention. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. High thermal conductivity and low expansion engineering plastic alloy, characterized by: It is composed of the following raw materials in parts by weight: Compound system: 100 parts; The compound system is composed of polyphenylene sulfide, polyetheretherketone and polyetherimide, wherein the polyphenylene sulfide is 50-70 parts; the polyetheretherketone is 20-30 parts; and the polyetherimide is 10-20 parts. High thermal conductivity filler: 30-150 parts; The high thermal conductivity filler is composed of boron nitride, aluminum nitride, aluminum oxide, silicon carbide and graphene, wherein the boron nitride is 10-25 parts; the aluminum nitride is 15-40 parts; the aluminum oxide is 20-60 parts; the silicon carbide is 10-30 parts; and the graphene is 3-10 parts. Low expansion filler: 10-80 parts; The low expansion filler is composed of fused silica powder, potassium titanate whiskers and carbon fibers, wherein the fused silica powder is 15-50 parts; the potassium titanate whiskers are 5-20 parts; and the carbon fibers are 8-25 parts. Interface modifier: 2-15 parts; The interface modifier is composed of a silane coupling agent, a maleic anhydride grafted polyolefin elastomer and a terminal hydroxyl hyperbranched polymer, wherein the silane coupling agent is 2-5 parts; the maleic anhydride grafted polyolefin elastomer is 3-8 parts; and the terminal hydroxyl hyperbranched polymer is 1-3 parts. The maleic anhydride grafted polyolefin elastomer is prepared by melt-blending POE with a density of 0.87 g / cm3 and a maleic anhydride elastomer substrate in a mass ratio of 100:1.5 in a twin-screw extruder, adding 0.1 wt% dicumyl peroxide to initiate free radical grafting, and simultaneously injecting styrene in an amount of 1 / 3 the mass of the maleic anhydride as a comonomer to inhibit degradation; Functional additives: 0.5-5 parts; The functional additive is composed of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, tris(2,4-di-tert-butylphenyl) phosphite and ethylene bisstearamide; The pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate: 0.3-1 part; the tris(2,4-di-tert-butylphenyl) phosphite: 0.2-0.5 part; and the ethylene bisstearamide: 0.5-2 parts.

2. The high thermal conductivity and low expansion engineering plastic alloy according to claim 1, characterized in that: The aluminum nitride is prepared by depositing a nano-silicon oxide layer with a thickness of 50-80 nm on aluminum nitride powder at 300° C. by plasma-enhanced chemical vapor deposition under nitrogen protection, and then wet-coating with an aminosilane / titanate composite coupling agent ethanol solution. The D50 is 1.5±0.2 μm and the specific surface area is 4-6 m2 / g.

3. The high thermal conductivity and low expansion engineering plastic alloy according to claim 2, characterized in that: The graphene is prepared by grafting fluorine-containing hyperbranched polyaryletherketone in a supercritical CO2 environment at a pressure of 15 MPa and a temperature of 50°C. The graphene has 6 layers, a sheet diameter of 25 μm, and a carbon-oxygen ratio of more than 200:

1.

4. The high thermal conductivity and low expansion engineering plastic alloy according to claim 3, characterized in that: The fused quartz powder is prepared by grafting glycidyl methacrylate and long-chain alkyl silane in sections at 400° C. in a fluidized bed reactor by vapor deposition. The sphericity is greater than 0.92, D90 is less than or equal to 3 μm, and the hydroxyl density is 1.8 per nm. 2 .

5. The high thermal conductivity and low expansion engineering plastic alloy according to claim 4, characterized in that: The carbon fiber is made by heating the fiber at a frequency of 40kHz and a current density of 0.5A / dm 2 In an ultrasonic-electrochemical combined bath, nanoscale pits were formed by anodic oxidation, and then a polydopamine / nanodiamond composite layer was deposited to obtain a surface groove with a length of 150±20μm, a diameter of 7μm, and a depth of less than 50nm.

6. The high thermal conductivity and low expansion engineering plastic alloy according to claim 4, characterized in that: The boron nitride is prepared by blending powder with polyetherimide powder in a high-speed impact mill at a mass ratio of 1:0.3, and then in-situ polymerization initiated by 2.45 GHz, 800 W microwave radiation. The aspect ratio is 100, and the B2O3 content is less than 500 ppm.

7. The high thermal conductivity and low expansion engineering plastic alloy according to claim 5, characterized in that: Potassium titanate whiskers are prepared by hydrothermally growing a nano-boehmite coating on whiskers in a subcritical water environment at 200°C and a pressure of 2MPa, and then hydrophobizing them with silazane vapor phase. The whiskers have an aspect ratio of 40, no free alkali on the surface, and a pH of 7±0.

5.

8. The method for preparing the high thermal conductivity and low expansion engineering plastic alloy according to claims 1 to 7, characterized in that: The following steps are involved: S1. First, pre-treat the filler and modify the surface: place 15-40 parts of aluminum nitride powder in a fluidized bed reactor at a flow rate of 8m 3 / h nitrogen protection by plasma enhanced chemical vapor deposition at 300 ° C with a power of 15 kW and a frequency of 13.56 MHz to deposit a 50-80 nm nano-silicon oxide layer, followed by spray injection of a 20 wt% aminosilane / titanate composite coupling agent ethanol solution, and drying and curing at 120 ° C; Simultaneously, 8-25 parts of carbon fiber were loaded into the ultrasound-electrochemical cell, and 40kHz / 2kW ultrasound and 0.5A / dm were started in 0.1mol / L sulfuric acid electrolyte. 2 / 30min anodic oxidation to form nano pits, and then immersed in pH = 8.5, 40℃ polydopamine / nanodiamond plating solution for deposition for 20 minutes; S2. Then perform matrix premixing and interfacial activation: 50-70 parts of polyphenylene sulfide, 20-30 parts of polyetheretherketone, and 10-20 parts of polyetherimide were added to a high-speed mixer at 800 rpm and 150 ° C for 5 minutes, and then vacuum dehydration was started at -0.09 MPa and 120 ° C for 30 min to a water content of ≤100 ppm. At the same time, 2-5 parts of aminosilane coupling agent and 1-3 parts of terminal hydroxyl hyperbranched polymer are pretreated in a supercritical CO2 reactor at 12MPa and 60°C for 20 minutes to generate a silanized hyperbranched composite agent, which is then dynamically mixed with 3-8 parts of maleic anhydride grafted polyolefin elastomer in a molten state at 180°C for 3 minutes to prepare a composite interface agent; S3 is then implemented multi-stage mixing: using a co-rotating twin-screw extruder according to the temperature zone segment operation: Zones 1-3 at 290-310°C where the main feed is added to the base plastic; In the fourth zone, 10-25 parts of aluminum nitride and 20-60 parts of aluminum oxide are added to the side feed at 300-320°C, and forced dispersion is carried out by a helical tooth block and a counter-rotating element; In the fifth zone, pretreated carbon fibers and 5-20 parts of potassium titanate whiskers are added vertically at 290-300°C, and a 45° bevel kneading block is used to induce fiber orientation, with an orientation degree of >85%; In zone 6, 3-10 parts of graphene and 10-25 parts of boron nitride are added to the side feed at 280-290°C; In zone 7, at 270-280°C, inject the composite interface agent using a liquid injection pump; Zone 8: 260-270℃, open -0.1MPa vacuum devolatilization; S4. Finally, electromagnetic field-assisted molding is performed: the melt is injected into the mold at 300±5°C. During the mold filling phase, a 0.8T axial 10Hz pulsed magnetic field is applied to orient the potassium titanate whiskers to an orientation angle of less than 15°. The injection pressure is 120-150MPa and the pressure is maintained in stages. The molded part is then transferred to an infrared annealing furnace for step-by-step curing.

9. The method for preparing a high thermal conductivity and low expansion engineering plastic alloy according to claim 8, characterized in that: In the step S4, during the staged pressure holding, in the first stage, after the melt fills the mold cavity, a high pressure of 80 MPa is immediately applied, and the pressure holding time lasts for 5 seconds; In the second stage, the low-pressure holding is performed when the pressure drops to 40 MPa and the holding time is extended to 10 seconds.

10. The method for preparing a high thermal conductivity and low expansion engineering plastic alloy according to claim 8, characterized in that: The infrared annealing furnace step curing process in step S4 is as follows: The substrate was treated at 180°C for 2 hours under a 15 MPa nitrogen atmosphere to allow the matrix resin to fully relax and complete the interfacial coupling reaction. Then the temperature was raised to 220°C and kept for 1 hour to promote the crystallization of polyetheretherketone and activate the negative expansion effect of fused silica powder; Finally, the temperature was maintained at 250°C for 0.5 hours to strengthen the cross-linking network of polyphenylene sulfide. The cooling rate was controlled to be ≤2°C / min throughout the process and then dropped to 80°C before being taken out of the oven.

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