A PEEK foam insulation high temperature stable phase radio frequency cable and its preparation process

Abstract

The present invention discloses a PEEK foamed insulated high-temperature phase-stable radio frequency cable and its preparation process, which relates to the technical field of wires and cables, and solves the problem that the cable is easily damaged during use because the insulation layer is easily aged and broken down when operating under frequent overload. A PEEK foamed insulated high-temperature phase-stable radio frequency cable comprises an inner conductor layer, an insulating layer, a shielding layer, an outer conductor layer and a sheath layer, and the insulating layer comprises the following components in parts by weight: 65 to 75 parts of polyetheretherketone; 5 to 10 parts of polyphenylene sulfide; 8 to 16 parts of alkyd resin; 3 to 5 parts of compatibilizer; 4 to 6 parts of physical foaming agent; 3 to 6 parts of titanium dioxide. The insulating layer in the PEEK foamed insulated high-temperature phase-stable radio frequency cable of the present invention is not easy to age or be broken down when operating under frequent overload, so that the PEEK foamed insulated high-temperature phase-stable radio frequency cable is not easy to be damaged during use, and the overall stability can be maintained.

Description

Technical Field

[0001] The present invention relates to the technical field of electric wires and cables, and more specifically, to a PEEK foamed insulation high-temperature stable-phase radio frequency cable and a preparation process thereof. Background Art

[0002] RF cable is a cable that transmits electromagnetic energy within the radio frequency range. RF cable is an indispensable component in various radio communication systems and electronic equipment. It is widely used in wireless communication and broadcasting, television, radar, navigation, computers and instrumentation.

[0003] A Chinese invention patent with publication number CN104575854A discloses a high mechanical strength radio frequency coaxial cable, which includes an inner conductor, an insulating layer, a shielding layer and an outer skin from the inside to the outside. The insulating layer is a foamed insulating layer, which includes the following components in weight percentage: 40-50% polyetheretherketone, 30-35% glass fiber, 4-6% compatibilizer, 10-15% nucleating agent and 3-6% physical foaming agent.

[0004] In the above patent, the mechanical strength of the RF coaxial cable, especially the tensile strength and traction strength of the insulation layer, is effectively improved by improving the structure, composition and process of the RF coaxial cable. However, some cables are inevitably frequently overloaded during use, which will increase the temperature of the cable and cause large temperature changes, which can easily cause aging of the insulation layer and breakdown of the insulation layer, causing damage to the cable. Therefore, a new solution is needed to solve the above problem. Summary of the invention

[0005] In view of the problem in the prior art that the insulation layer is prone to aging and breakdown when operating under frequent overloads, which causes the cable to be easily damaged during use, the first object of the present invention is to provide a PEEK foamed insulated high-temperature phase-stable radio frequency cable, which solves the above-mentioned technical problem by adding polyphenylene sulfide and alkyd resin and making them have a good composite synergistic effect with each other. The cable is not easy to be damaged during use, and the internal insulation layer is not easy to age and be broken down.

[0006] To achieve the above objective 1, the present invention provides the following technical solution:

[0007] A PEEK foam insulated high temperature phase-stable radio frequency cable, comprising an inner conductor layer, an insulating layer, a shielding layer, an outer conductor layer and a sheath layer, characterized in that the insulating layer comprises the following components in parts by weight:

[0008] 65-75 parts of polyetheretherketone;

[0009] Polyphenylene sulfide 5-10 parts;

[0010] 8-16 parts of alkyd resin;

[0011] 3-5 parts of compatibilizer;

[0012] 4-6 parts of physical foaming agent;

[0013] 3 to 6 parts of titanium dioxide.

[0014] By adopting the above technical solution, polyetheretherketone (PEEK) has physical and chemical properties such as high temperature resistance and chemical corrosion resistance, and can be used as high temperature resistant structural materials and electrical insulation materials. When polyetheretherketone is used as the main material, the insulation layer as a whole can have good mechanical strength, high temperature resistance, impact resistance, flame retardancy, acid and alkali resistance, hydrolysis resistance, wear resistance, fatigue resistance, radiation resistance and good electrical properties. Titanium dioxide is a good inorganic filler, which has a good ultraviolet shielding effect, and has good dispersibility and filling properties in other component raw materials. It also uses its own good high temperature resistance to greatly improve the stability of PEEK foam insulation high temperature stable phase radio frequency cable during overload operation. The compatibilizer can greatly improve the bonding between the component raw materials, thereby making the obtained insulation layer have higher quality.

[0015] Polyphenylene sulfide is a new type of high-performance thermoplastic resin with the advantages of high mechanical strength, high temperature resistance, chemical resistance, flame retardancy, good thermal stability, and excellent electrical properties, which makes the insulation layer have good high temperature resistance. After the alkyd resin is cured into a film, it has gloss and toughness, strong adhesion, and good wear resistance, weather resistance, and insulation, etc., which can make the insulation layer fit tightly to the outside of the inner conductor layer and not easy to age. At the same time, when polyphenylene sulfide and alkyd resin are mixed, they can play a good compounding and synergistic role, which can not only improve the bonding and fluidity of each raw material in the molten state, but also make the formed insulation layer have high aging resistance, which is conducive to making the PEEK foamed insulated high-temperature stable phase RF cable maintain good stability and not easy to be damaged when operating under frequent overloads.

[0016] More preferably, the insulating layer further comprises 8 to 12 parts by weight of a functional filler, wherein the functional filler is mainly composed of glass powder, ceramic powder and mica powder in any weight ratio.

[0017] By adopting the above technical scheme, glass powder is made of raw materials such as high-temperature and high-purity silicon oxide and aluminum oxide, and then undergoes an ultra-clean production process to form a disordered glass transparent powder with stable chemical properties. It is also a super weather-resistant powder material with acid and alkali resistance, chemical inertness, and low expansion coefficient; ceramic powder is mainly a ceramic material with aluminum oxide as the main body, which has high heat resistance, low density, low ignition loss, good light scattering, and good insulation; mica powder has good insulation, high temperature resistance and acid and alkali corrosion resistance, strong overall adhesion, and excellent ability to shield ultraviolet rays and infrared rays; and the addition of functional fillers composed of glass powder, ceramic powder and mica powder can improve the overall high temperature resistance of the insulation layer, making it less likely to age during use, and the functional fillers can also play a certain heat dissipation effect, thereby enabling the PEEK foamed insulation high-temperature stable phase radio frequency cable to maintain good stability during operation.

[0018] Further preferably, 3 to 8 parts by weight of a heat-stable filler are added to the components of the insulating layer, and the heat-stable filler mainly includes carbon fiber and graphene, and the weight ratio of carbon fiber to graphene is 1:(0.9 to 1.3).

[0019] By adopting the above technical solutions, carbon fiber has excellent mechanical properties, high specific modulus and specific strength, high temperature resistance, abrasion resistance, corrosion resistance, fatigue resistance, low density, low thermal expansion coefficient, easy textile processing, high electromagnetic shielding, high thermal conductivity and electrical conductivity, etc. Graphene is known as the thinnest, strongest and most conductive material in the world so far. It also has the advantages of ultra-high thermal conductivity, good lubricity, large specific surface area and good flame retardancy. The addition of heat-stable fillers composed of carbon fiber and graphene has good filling and dispersibility between the raw materials of each component, and makes the insulation layer have good fluidity and easy processing performance in the molten state. In addition, the cooperation between carbon fiber and graphene can greatly improve the overall temperature resistance and anti-aging performance of the insulation layer.

[0020] More preferably, the inner conductor layer is made of silver-plated soft round copper wire.

[0021] More preferably, the shielding layer is formed by wrapping a silver-plated copper flat tape.

[0022] More preferably, the outer conductor layer is woven from silver-plated copper wires.

[0023] More preferably, the sheath layer is made of PEEK.

[0024] More preferably, the compatibilizer is maleic anhydride grafted EBA compatibilizer.

[0025] By adopting the above technical scheme, the main component of the maleic anhydride grafted EBA compatibilizer is ethylene butyl acrylate copolymer, which introduces strong polar reactive groups to make the material have high polarity and reactivity. It is a polymer interface coupling agent, compatibilizer, and dispersion promoter, which can greatly improve the compatibility of benzene sulfide, alkyd resin and polyetheretherketone, thereby making the PEEK foamed insulation high-temperature stable phase radio frequency cable have higher quality as a whole.

[0026] More preferably, the physical foaming agent is any one of n-hexane, petroleum ether and dichlorotetrafluoroethane.

[0027] By adopting the above technical scheme, n-hexane, petroleum ether and dichlorotetrafluoroethane are all good physical foaming agents, which have high foaming multiples, good foam stability, and good compatibility with other component raw materials.

[0028] The second object of the present invention is to provide a preparation process of a PEEK foamed insulation high-temperature stable-phase radio frequency cable. The PEEK foamed insulation high-temperature stable-phase radio frequency cable prepared by this process is not easily damaged during use, and its internal insulation layer is not easily aged and broken down.

[0029] To achieve the above-mentioned second objective, the present invention provides the following technical solution, comprising the following steps:

[0030] Step 1, adding corresponding weight portions of polyetheretherketone, polyphenylene sulfide, alkyd resin, compatibilizer and titanium dioxide into a twin-screw extruder, stirring and melting them, and controlling the barrel temperature at 250-270° C.;

[0031] Step 2, injecting a physical foaming agent into the barrel at an injection pressure of 30 to 40 MPa, stirring thoroughly for 15 to 20 minutes to obtain a mixed raw material;

[0032] Step 3: preheat the inner conductor layer at 85-90°C, then extrude the mixed raw materials in the barrel through an extruder and coat the inner conductor at a temperature of 340-450°C.

[0033] Step 4: Cool the inner conductor layer coated with the mixed raw material in cold water at 5 to 10° C. for 3 to 5 minutes, and then cool it at room temperature for 8 to 10 minutes, so that the mixed raw material forms a stable insulating layer on the outside of the inner conductor layer;

[0034] Step five: first wrap a silver-plated copper flat tape around the outside of the insulation layer to form a shielding layer, then weave a silver-plated copper wire around the outside of the shielding layer to form an outer conductor layer, and finally wrap a sheath layer made of PEEK around the outside of the outer conductor layer to obtain a PEEK foamed insulation high-temperature phase-stable RF cable.

[0035] By adopting the above technical solution, the inner conductor layer is first preheated, and then the mixed raw materials in the barrel are extruded through an extruder and coated on the outer periphery of the inner conductor, which is conducive to avoiding the reduction of the overall quality of the PEEK foam insulation high-temperature stable phase RF cable due to the large temperature difference between the conductor layer and the mixed raw materials. The inner conductor layer coated with the mixed raw materials is first cooled in cold water and then cooled at room temperature, which is conducive to the mixed raw materials forming a stable and good insulation layer on the outside of the inner conductor layer. At the same time, the process is simple to operate, has high production efficiency, and will not cause significant pollution to the environment, and has good applicability in actual use.

[0036] In summary, compared with the prior art, the present invention has the following beneficial effects:

[0037] (1) Adding polyphenylene sulfide and alkyd resin is conducive to making the insulation layer have good high temperature resistance, and when they are mixed, they can play a good compounding and synergistic role, which can not only improve the bonding and fluidity of each raw material in the molten state, but also make the formed insulation layer have high aging resistance, which is conducive to making the PEEK foam insulation high temperature stable phase radio frequency cable maintain good stability and not easy to be damaged when operating under frequent overload;

[0038] (2) Adding functional fillers composed of glass powder, ceramic powder and mica powder can improve the overall high temperature resistance of the insulation layer, making it less prone to aging during use, and the functional fillers can also play a certain heat dissipation effect, thereby enabling the PEEK foam insulation high temperature stable phase RF cable to maintain good stability during operation;

[0039] (3) The addition of heat-stable fillers composed of carbon fiber and graphene makes the insulation layer have good fluidity and easy processing performance in the molten state. The carbon fiber and graphene cooperate with each other to greatly improve the overall temperature resistance and anti-aging performance of the insulation layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 The present invention is a process flow chart for preparing the PEEK foam insulation high temperature stable phase radio frequency cable. DETAILED DESCRIPTION

[0041] The present invention is described in detail below in conjunction with the accompanying drawings and embodiments.

[0042] Example 1: A PEEK foam insulated high temperature phase-stable radio frequency cable, which comprises an inner conductor layer, an insulating layer, a shielding layer, an outer conductor layer and a sheath layer from the inside to the outside, and the components in the insulating layer and their corresponding weight fractions are shown in Table 1, and is prepared by the following steps:

[0043] Step 1: Add corresponding weight portions of polyetheretherketone, polyphenylene sulfide, alkyd resin, compatibilizer and titanium dioxide into a twin-screw extruder, stir and melt them thoroughly, control the barrel temperature at 270° C., stir at 300 rpm, and stir and melt for 40 min;

[0044] Step 2, injecting n-hexane into the barrel at an injection pressure of 40 MPa, stirring thoroughly for 20 min at a stirring speed of 500 rpm to obtain a mixed raw material;

[0045] Step 3: preheat the inner conductor layer at 90°C, then extrude the mixed raw materials in the barrel through an extruder and coat the outer periphery of the inner conductor at a temperature of 400°C;

[0046] Step 4: Cool the inner conductor layer coated with the mixed raw material in cold water at 10° C. for 5 minutes, and then cool it at room temperature for 9 minutes, so that the mixed raw material forms a stable insulating layer outside the inner conductor layer;

[0047] Step five: first wrap a silver-plated copper flat tape around the outside of the insulation layer to form a shielding layer, then weave a silver-plated copper wire around the outside of the shielding layer to form an outer conductor layer, and finally wrap a sheath layer made of PEEK around the outside of the outer conductor layer to obtain a PEEK foamed insulation high-temperature phase-stable RF cable.

[0048] Note: In the above steps, the inner conductor layer is made of silver-plated soft round copper wire; the shielding layer is wrapped with silver-plated copper flat tape; the outer conductor layer is woven with silver-plated copper wire; the sheath layer is made of PEEK; and the compatibilizer is maleic anhydride grafted EBA compatibilizer.

[0049] Example 2-8: A PEEK foam insulated high-temperature phase-stable radio frequency cable, which is different from Example 1 in that the components in the insulation layer and their corresponding weight fractions are as shown in Table 1.

[0050] Table 1 Components and their weight fractions in Examples 1-8

[0051]

[0052] Example 9: A PEEK foam insulated high-temperature phase-stable radio frequency cable. The difference from Example 1 is that step two is specifically set to inject petroleum ether into the barrel with an injection pressure of 40 MPa, fully stir for 20 minutes and a stirring speed of 500 rpm to obtain a mixed raw material.

[0053] Example 10: A PEEK foam insulated high-temperature phase-stable radio frequency cable. The difference from Example 1 is that step two is specifically set to inject dichlorotetrafluoroethane into the barrel with an injection pressure of 40 MPa, fully stir for 20 minutes, and stir at a speed of 500 rpm to obtain a mixed raw material.

[0054] Example 11: A PEEK foam insulated high-temperature phase-stable radio frequency cable, which is different from Example 1 in that step one is specifically configured as follows: 65 parts by weight of polyetheretherketone, 10 parts of polyphenylene sulfide, 8 parts of alkyd resin, 5 parts of compatibilizer and 4.5 parts of titanium dioxide are added to a twin-screw extruder, stirred and melted, the barrel temperature is controlled at 270°C, the stirring speed is 300rpm, the stirring and melting time is 40min, and then 8 parts by weight of functional filler are added, and stirring is continued for 15min, and the functional filler is composed of glass powder, ceramic powder and mica powder in a weight ratio of 1:3:1.

[0055] Example 12: A PEEK foam insulated high-temperature phase-stable radio frequency cable, which is different from Example 1 in that step one is specifically configured as follows: 65 parts by weight of polyetheretherketone, 10 parts of polyphenylene sulfide, 8 parts of alkyd resin, 5 parts of compatibilizer and 4.5 parts of titanium dioxide are added to a twin-screw extruder, stirred and melted, the barrel temperature is controlled at 270°C, the stirring speed is 300rpm, the stirring and melting time is 40min, and then 10 parts by weight of functional filler is added, and stirring is continued for 15min, and the functional filler is composed of glass powder, ceramic powder and mica powder in a weight ratio of 2:1:3.

[0056] Example 13: A PEEK foam insulated high-temperature phase-stable radio frequency cable, which is different from Example 1 in that step one is specifically configured as follows: 65 parts by weight of polyetheretherketone, 10 parts of polyphenylene sulfide, 8 parts of alkyd resin, 5 parts of compatibilizer and 4.5 parts of titanium dioxide are added to a twin-screw extruder, and the mixture is fully stirred and melted. The barrel temperature is controlled at 270°C, the stirring speed is 300rpm, the stirring and melting time is 40min, and then 12 parts by weight of a functional filler is added, and stirring is continued for 15min. The functional filler is composed of glass powder, ceramic powder and mica powder in a weight ratio of 4:7:3.

[0057] Example 14: A PEEK foam insulated high-temperature phase-stable radio frequency cable, which is different from Example 1 in that step one is specifically configured as follows: 65 parts by weight of polyetheretherketone, 10 parts of polyphenylene sulfide, 8 parts of alkyd resin, 5 parts of compatibilizer and 4.5 parts of titanium dioxide are added to a twin-screw extruder, and the mixture is fully stirred and melted. The barrel temperature is controlled at 270°C, the stirring speed is 300rpm, the stirring and melting time is 40min, and then 3 parts by weight of a heat-stable filler is added, and stirring is continued for 15min, wherein the heat-stable filler is composed of carbon fiber and graphene in a weight ratio of 1:1.1.

[0058] Example 15: A PEEK foam insulated high-temperature phase-stable radio frequency cable, which is different from Example 1 in that step one is specifically configured as follows: 65 parts by weight of polyetheretherketone, 10 parts of polyphenylene sulfide, 8 parts of alkyd resin, 5 parts of compatibilizer and 4.5 parts of titanium dioxide are added to a twin-screw extruder, stirred and melted, the barrel temperature is controlled at 270°C, the stirring speed is 300rpm, the stirring and melting time is 40min, and then 8 parts by weight of a heat-stable filler is added, and stirring is continued for 15min, and the heat-stable filler is composed of carbon fiber and graphene in a weight ratio of 1:1.3.

[0059] Example 16: A PEEK foam insulated high-temperature phase-stable radio frequency cable, which is different from Example 1 in that step one is specifically configured as follows: 65 parts by weight of polyetheretherketone, 10 parts of polyphenylene sulfide, 8 parts of alkyd resin, 5 parts of compatibilizer and 4.5 parts of titanium dioxide are added to a twin-screw extruder, and the mixture is fully stirred and melted. The barrel temperature is controlled at 270°C, the stirring speed is 300rpm, the stirring and melting time is 40min, and then 5.5 parts by weight of a heat-stable filler is added, and stirring is continued for 15min. The heat-stable filler is composed of carbon fiber and graphene in a weight ratio of 1:0.9.

[0060] Comparative Example 1: A PEEK foam insulated high-temperature phase-stable radio frequency cable, which is different from Example 1 in that step one is specifically configured as follows: 65 parts by weight of polyetheretherketone, 10 parts of polyphenylene sulfide, 5 parts of a compatibilizer and 4.5 parts of titanium dioxide are added to a twin-screw extruder, and the mixture is fully stirred and melted. The barrel temperature is controlled at 270°C, the stirring speed is 300rpm, and the stirring and melting time is 40min.

[0061] Comparative Example 2: A PEEK foam insulated high-temperature phase-stable radio frequency cable, which is different from Example 1 in that step one is specifically configured as follows: 65 parts by weight of polyetheretherketone, 8 parts of alkyd resin, 5 parts of compatibilizer and 4.5 parts of titanium dioxide are added to a twin-screw extruder, and the mixture is fully stirred and melted. The barrel temperature is controlled at 270°C, the stirring speed is 300rpm, and the stirring and melting time is 40min.

[0062] Comparative Example 3: A PEEK foam insulated high-temperature phase-stable radio frequency cable, which is different from Example 1 in that step one is specifically configured as follows: 65 parts by weight of polyetheretherketone, 5 parts of a compatibilizer and 4.5 parts of titanium dioxide are added to a twin-screw extruder, and the mixture is fully stirred and melted. The barrel temperature is controlled at 270°C, the stirring speed is 300rpm, and the stirring and melting time is 40min.

[0063] Performance test samples: The PEEK foamed insulated high temperature stable phase radio frequency cable obtained in Example 1-16 was used as test sample 1-16, and the PEEK foamed insulated high temperature stable phase radio frequency cable obtained in Comparative Example 1-3 was used as control sample 1-3.

[0064] Test method: Take test samples 1-16 and control samples 1-3 of the same length as test samples, then apply corresponding voltage to both ends of the test samples, slowly increase the voltage from zero to the rated value within 50 seconds, keep it for 10 minutes, then let the test sample be overloaded by 15% for 10 minutes, and finally reduce the voltage to zero within 65 seconds, which is one cycle of the test sample. Repeat the above test until the insulation layer of the test sample is broken down during the test, and record the cycle of the repeated test at this time.

[0065] Table 2 Test results of test samples 1-16 and control samples 1-3

[0066] sample Cycle times Test sample 1 156 Test sample 2 159 Test sample 3 158 Test sample 4 161 Test sample 5 157 Test sample 6 158 Test sample 7 159 Test sample 8 157 Test sample 9 158 Test sample 10 157 Test sample 11 184 Test sample 12 183 Test sample 13 182 Test sample 14 192 Test sample 15 193 Test sample 16 191 Control sample 1 138 Control sample 2 136 Control sample 3 66

[0067] Test results: The test results of test samples 1-16 and control samples 1-3 are shown in Table 2. As shown in Table 2, by comparing the test results of test samples 1-8 and control samples 1-3, it can be seen that the addition of polyphenylene sulfide and alkyd resin can make the PEEK foam insulation high temperature stable phase radio frequency cable maintain good stability under frequent overloads, and when polyphenylene sulfide and alkyd resin are mixed, the overall stability of the PEEK foam insulation high temperature stable phase radio frequency cable can be greatly improved. By comparing the test results of test samples 1-8 and test samples 11-13, it can be seen that the addition of functional fillers composed of glass powder, ceramic powder and mica powder can make the insulation layer in the PEEK foam insulation high temperature stable phase radio frequency cable not easy to be broken down due to aging. By comparing the test results of test samples 1-8 and test samples 14-16, it can be seen that the addition of heat-stable fillers composed of carbon fiber and graphene makes the insulation layer in the PEEK foam insulation high temperature stable phase radio frequency cable not easy to be broken down under frequent overloads.

[0068] The above is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the present invention should also be regarded as the protection scope of the present invention.

Claims

1. A PEEK foam insulated high temperature phase-stable radio frequency cable, comprising an inner conductor layer, an insulating layer, a shielding layer, an outer conductor layer and a sheath layer, characterized in that: The insulating layer comprises the following components in parts by weight: 65-75 parts of polyetheretherketone; Polyphenylene sulfide 5-10 parts; 8-16 parts of alkyd resin; 3-5 parts of compatibilizer; 4-6 parts of physical foaming agent; 3 to 6 parts of titanium dioxide.

2. The PEEK foam insulated high temperature phase-stable radio frequency cable according to claim 1, characterized in that: The components of the insulating layer are further added with 8 to 12 parts by weight of functional filler, which is mainly composed of glass powder, ceramic powder and mica powder in any weight ratio.

3. The PEEK foam insulated high temperature phase-stable radio frequency cable according to claim 1, characterized in that: The components of the insulating layer are also added with 3 to 8 parts by weight of a heat-stable filler, which mainly includes carbon fiber and graphene, and the weight ratio of carbon fiber to graphene is 1:(0.9 to 1.3).

4. The PEEK foam insulated high temperature phase-stable radio frequency cable according to claim 1, characterized in that: The inner conductor layer is made of silver-plated soft round copper wire.

5. The PEEK foam insulated high temperature phase-stable radio frequency cable according to claim 1, characterized in that: The shielding layer is formed by wrapping a silver-plated copper flat tape.

6. The PEEK foam insulated high temperature phase-stable radio frequency cable according to claim 1, characterized in that: The outer conductor layer is braided with silver-plated copper wires.

7. The PEEK foam insulated high temperature phase-stable radio frequency cable according to claim 1, characterized in that: The sheath layer is made of PEEK.

8. The PEEK foam insulated high temperature phase-stable radio frequency cable according to claim 1, characterized in that: The compatibilizer is maleic anhydride grafted EBA compatibilizer.

9. The PEEK foam insulated high temperature phase-stable radio frequency cable according to claim 1, characterized in that: The physical foaming agent is any one of n-hexane, petroleum ether and dichlorotetrafluoroethane.

10. A process for preparing a PEEK foam insulated high temperature phase-stable radio frequency cable as claimed in claim 1, characterized in that: The following steps are involved: Step 1, adding corresponding weight portions of polyetheretherketone, polyphenylene sulfide, alkyd resin, compatibilizer and titanium dioxide into a twin-screw extruder, stirring and melting them, and controlling the barrel temperature at 250-270° C.; Step 2, injecting a physical foaming agent into the barrel at an injection pressure of 30 to 40 MPa, stirring thoroughly for 15 to 20 minutes to obtain a mixed raw material; Step 3: preheat the inner conductor layer at 85-90°C, then extrude the mixed raw materials in the barrel through an extruder and coat the inner conductor at a temperature of 340-450°C. Step 4: Cool the inner conductor layer coated with the mixed raw material in cold water at 5 to 10° C. for 3 to 5 minutes, and then cool it at room temperature for 8 to 10 minutes, so that the mixed raw material forms a stable insulating layer on the outside of the inner conductor layer; Step five: first wrap a silver-plated copper flat tape around the outside of the insulation layer to form a shielding layer, then weave a silver-plated copper wire around the outside of the shielding layer to form an outer conductor layer, and finally wrap a sheath layer made of PEEK around the outside of the outer conductor layer to obtain a PEEK foamed insulation high-temperature phase-stable RF cable.

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