Polytetrafluoroethylene insulated cable and preparation process thereof

Abstract

The invention relates to the technical field of cables, in particular to a polytetrafluoroethylene insulated cable and a preparation process thereof. The preparation method comprises the following steps: irradiating a polytetrafluoroethylene film with a cobalt source, and grafting glycidyl methacrylate on the surface of the polytetrafluoroethylene film; the preparation method comprises the following steps: by taking allylamine and 1, 1, 3, 3-tetramethyldisiloxane as raw materials, carrying out hydrosilylation reaction to obtain amino-terminated tetramethyldisiloxane, reacting the product with biphenyltetracarboxylic dianhydride, and then adding trimellitic anhydride for blocking to obtain carboxyl-terminated silicon-containing polyimide; mixing carboxyl-terminated silicon-containing polyimide, epoxy resin, a curing agent, nano silicon carbide, a silane coupling agent and an antioxidant to obtain an epoxy resin glue solution; coating a polytetrafluoroethylene film on the surface of the silver-plated copper conductor wire core, coating an epoxy resin glue solution, and curing to obtain an insulating layer; attaching a silver film on the surface of the insulating layer to form a shielding layer; and coating a PFA sheath on the surface of the shielding layer to obtain the product. The polytetrafluoroethylene insulated cable prepared by the invention has good waterproof, wear-resistant and corrosion-resistant properties.

Description

Technical Field

[0001] The invention relates to the technical field of cables, in particular to a polytetrafluoroethylene insulated cable and a preparation process thereof. Background Art

[0002] Cable is a medium for transmitting electric energy and information. It has a wide range of applications in the fields of electrical communications, transportation, industrial production, etc. With the rapid development of technology, the demand for cable materials in various industries is increasing day by day, and the requirements for cable materials are also getting higher and higher.

[0003] In order to avoid cable equipment failure and eliminate potential safety hazards, it is usually necessary to set up a waterproof layer to prevent moisture from penetrating into the interior, so as to achieve waterproof and moisture-proof effects and extend the service life of the cable. Polytetrafluoroethylene is a high molecular polymer made by polymerizing tetrafluoroethylene as a monomer. It has good hydrophobicity and water resistance. In addition, it also has outstanding heat resistance, cold resistance, acid and alkali resistance, so it is called the "King of Plastics". However, polytetrafluoroethylene has problems such as low strength and poor wear resistance, which limits its application in cables. Summary of the invention

[0004] The object of the present invention is to provide a polytetrafluoroethylene insulated cable and a preparation process thereof to solve the problems raised in the above background technology.

[0005] In order to solve the above technical problems, the present invention provides the following technical solutions: a polytetrafluoroethylene insulated cable and a preparation process thereof, comprising the following steps: The surface of the silver-plated copper conductor core is coated with a polytetrafluoroethylene film and an epoxy resin glue with a coating thickness of 50-80 μm, and cured at 100-120° C. to obtain an insulating layer; a silver film is attached to the surface of the insulating layer to form a shielding layer; and a PFA sheath is coated on the surface of the shielding layer to obtain the product.

[0006] Furthermore, the method for preparing the polytetrafluoroethylene membrane comprises the following steps: S1: Mix polytetrafluoroethylene resin and auxiliary oil, and then prepare blanks after standing and aging; extrude the blanks into strips, and then shape them after calendering and stretching to obtain a polytetrafluoroethylene film with a thickness of 0.2-0.3 mm; S2: Place the polytetrafluoroethylene membrane in the presence of oxygen 60 Pre-irradiate in a Co cobalt source and take it out after reaching an absorbed dose of 8~15kGy; prepare a 35~40% mass concentration of glycidyl methacrylate / chlorobenzene solution, pass nitrogen for 30 minutes, use benzoyl peroxide as an initiator, soak the polytetrafluoroethylene membrane in the glycidyl methacrylate / chlorobenzene solution, raise the temperature to 80~90℃ and react for 4~6h; wash with acetone and dry.

[0007] Furthermore, in S1, 100 parts of polytetrafluoroethylene resin and 15 to 20 parts of auxiliary oil are mixed by weight.

[0008] Furthermore, in S2, the aging time is 24-30 hours; the billet forming pressure is 2-3 MPa; and the shaping temperature is 300-400°C.

[0009] Further, in S2, the polytetrafluoroethylene membrane is immersed in a glycidyl methacrylate / chlorobenzene solution at a bath ratio of 1:(10-15).

[0010] Furthermore, the preparation method of the epoxy resin adhesive is as follows: by weight percentage, 10-18% of terminal carboxyl silicon-containing polyimide and 82-90% of epoxy resin are mixed to obtain a modified epoxy resin; by weight percentage, 100 parts of modified epoxy resin, 46-57 parts of curing agent, 18-25 parts of nano-silicon carbide, 10-12 parts of silane coupling agent, and 3-5 parts of antioxidant are mixed to obtain an epoxy resin adhesive.

[0011] Furthermore, the preparation method of the carboxyl-terminated silicon-containing polyimide comprises the following steps: a. Allylamine is dispersed in tetrahydrofuran, and 1,1,3,3-tetramethyldisiloxane is added under nitrogen atmosphere with isopropanol solution of chloroplatinic acid as catalyst, and the temperature is raised to 60-70°C for reaction for 5-8h; after the solvent is evaporated under reduced pressure, the mixture is washed with methanol and dried to obtain amino-terminated tetramethyldisiloxane; b. Disperse terminal aminotetramethyldisiloxane and biphenyltetracarboxylic acid dianhydride in N-methylpyrrolidone, react for 6-8 hours under nitrogen environment, heat to 70-80°C, add trimellitic anhydride for end-capping reaction for 2-3 hours, and obtain terminal carboxyl silicon-containing polyimide.

[0012] Furthermore, in step a, the molar ratio of allyl group to 1,1,3,3-tetramethyldisiloxane is 1:1.

[0013] Furthermore, in step b, amino-terminated tetramethyl disiloxane and biphenyltetracarboxylic acid dianhydride are dispersed in N-methylpyrrolidone at a molar ratio of (1.2-1.5):1.

[0014] Compared with the prior art, the beneficial effects achieved by the present invention are as follows: the present invention provides a polytetrafluoroethylene insulated cable. Polytetrafluoroethylene has good corrosion resistance and hydrophobicity. When used as an insulating material to coat the cable, the service life and safety of the cable can be effectively improved.

[0015] In order to prevent the polytetrafluoroethylene on the surface of the cable from being scratched and damaged by external forces during use, the present invention coats the surface of the polytetrafluoroethylene insulated cable with epoxy resin glue for protection. Epoxy resin itself has good wear resistance, and the present invention also adds nano silicon carbide to further improve the wear resistance of the epoxy resin coating. Since the molecular chain of polytetrafluoroethylene is composed of carbon (C) and fluorine (F) atoms, each carbon atom is connected to two fluorine atoms, and the surface of polytetrafluoroethylene is almost completely covered by fluorine atoms. The electronegativity of fluorine atoms is very strong, so it forms a very stable chemical barrier, so its surface shows extremely strong non-stickiness. To this end, the present invention uses a cobalt source to irradiate the polytetrafluoroethylene film, and uses glycidyl methacrylate to graft and modify the irradiated polytetrafluoroethylene, and introduces epoxy groups on its surface. Epoxy-modified polytetrafluoroethylene can form stable chemical bonds through reaction during the curing process of epoxy resin, and the binding force between the two is improved, avoiding the wear of the polytetrafluoroethylene surface caused by sliding friction due to poor adhesion during the friction process, thereby protecting the cable.

[0016] Considering the poor toughness of epoxy resin, the coating may break due to bending by external force during the actual use of the cable. The present invention uses carboxyl-terminated silicon-containing polyimide to modify the epoxy resin. When preparing the silicon-containing polyimide, allylamine and 1,1,3,3-tetramethyldisiloxane are reacted to obtain amino-terminated tetramethyldisiloxane; amino-terminated tetramethyldisiloxane and biphenyltetracarboxylic acid dianhydride are then reacted, and trimellitic anhydride is used to cap the end to obtain carboxyl-terminated silicon-containing polyimide. The carboxyl group of the carboxyl-terminated silicon-containing polyimide can undergo an esterification reaction with the epoxy group on the epoxy resin, thereby introducing the silicon-containing polyimide molecular chain segment into the epoxy resin cross-linked network, thereby improving the toughness and hydrophobicity of the epoxy resin coating. It should be supplemented that when the amount of carboxyl-terminated silicon-containing polyimide is too high, its compatibility with the epoxy resin is reduced, and the modification effect will be greatly reduced. After repeated attempts, it was found that, by weight percentage, mixing 10-18% of terminal carboxyl silicon-containing polyimide and 82-90% of epoxy resin gave the best modified epoxy resin performance.

[0017] It should be noted that when conventional technologies in this field use polytetrafluoroethylene as an insulating layer, due to the strong non-stickiness of the polytetrafluoroethylene surface, it is impossible to effectively combine the shielding layer with the insulating layer by spraying or attaching. Therefore, most of them adopt the method of first making the silver wire into a silver wire woven mesh, and then using the silver wire woven mesh to cover the polytetrafluoroethylene insulating layer to form a silver shielding layer. However, due to the limitations of technology and operating processes, the thickness of the silver wire woven mesh is usually between 0.1 and 0.15 mm, and the present invention covers the surface of the polytetrafluoroethylene with an epoxy resin coating, so that the surface of the insulating layer can be coated with a silver shielding layer with a thickness of less than 10 μm by directly coating silver paste or adhering a silver film. The thickness of the silver shielding layer is only 10% of the prior art, and the weight is reduced to 1%, which is conducive to achieving lightweight cables. DETAILED DESCRIPTION

[0018] Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative work shall fall within the scope of protection of the present invention.

[0019] Materials and sources used in the present invention: silver film (10 μm) comes from Jiangsu Namida Optoelectronics Technology Co., Ltd.; polytetrafluoroethylene resin (model JF-4DE10) comes from Hangzhou Jufu New Material Technology Co., Ltd.; auxiliary oil is petroleum ether 60-90, which comes from Suzhou Jiading Chemical Technology Co., Ltd.; epoxy resin (E51) comes from Hebei Linyuan Fine Chemical Co., Ltd.; curing agent is triethylenetetramine; nano silicon carbide (particle size 40 nm) comes from Beijing Dekedaojin Technology Co., Ltd.; silane coupling agent is KH550; antioxidant is antioxidant 1076; PFA sheath material (model FC-103) comes from Hangzhou Jingfu Technology Co., Ltd.

[0020] Embodiment 1: A polytetrafluoroethylene insulated cable and a preparation process thereof, comprising the following steps: Step 1: Preparation of polytetrafluoroethylene membrane: S11: 100 g of polytetrafluoroethylene resin and 18 g of auxiliary oil were mixed, left to stand for aging for 24 h, and blanked at 2 MPa; the blank was extruded into strips, and after calendering and stretching, it was shaped at 300° C. to obtain a polytetrafluoroethylene film with a thickness of 0.3 mm; S12: Place the polytetrafluoroethylene membrane in an aerobic environment. 60 Pre-irradiate in a Co cobalt source and take it out after reaching an absorbed dose of 8 kGy; prepare a 35% mass concentration of glycidyl methacrylate / chlorobenzene solution, pass nitrogen for 30 minutes, use benzoyl peroxide as an initiator, soak the polytetrafluoroethylene membrane in the glycidyl methacrylate / chlorobenzene solution at a bath ratio of 1:10, heat to 80°C and react for 4 hours; wash with acetone and dry; Step 2: S21: Allylamine is dispersed in tetrahydrofuran, and 1,1,3,3-tetramethyldisiloxane is added in a nitrogen environment using an isopropanol solution of chloroplatinic acid as a catalyst, and the temperature is raised to 60°C for reaction for 5 hours; after the solvent is evaporated under reduced pressure, the terminal aminotetramethyldisiloxane is obtained by washing with methanol and drying; the molar ratio of allyl group to 1,1,3,3-tetramethyldisiloxane is 1:1; S22: dispersing terminal aminotetramethyldisiloxane and biphenyltetracarboxylic acid dianhydride in N-methylpyrrolidone in a molar ratio of 1.2:1, reacting for 6 hours under a nitrogen environment, heating to 70° C., adding trimellitic anhydride for end-capping and reacting for 2 hours to obtain a carboxyl-terminated silicon-containing polyimide; S23: By weight percentage, 10% of carboxyl-terminated silicon-containing polyimide and 90% of epoxy resin are mixed to obtain a modified epoxy resin; 100 g of the modified epoxy resin, 53 g of a curing agent, 25 g of nano-silicon carbide, 11 g of a silane coupling agent, and 3.8 g of an antioxidant are mixed to obtain an epoxy resin glue; Step 3: The surface of the silver-plated copper conductor core is coated with a polytetrafluoroethylene film in S12 and an epoxy resin glue with a coating thickness of 80 μm, and cured at 100° C. to obtain an insulating layer; a silver film is attached to the surface of the insulating layer to form a shielding layer; and a PFA sheath is coated on the surface of the shielding layer to obtain a product.

[0021] Embodiment 2: A polytetrafluoroethylene insulated cable and a preparation process thereof, comprising the following steps: Step 1: Preparation of polytetrafluoroethylene membrane: S11: 100 g of polytetrafluoroethylene resin and 18 g of auxiliary oil were mixed, left to stand for aging for 27 h, and blanked at 2.5 MPa; the blank was extruded into strips, and after calendering and stretching, it was shaped at 350° C. to obtain a polytetrafluoroethylene film with a thickness of 0.3 mm; S12: Place the polytetrafluoroethylene membrane in an aerobic environment. 60 Pre-irradiate in a Co cobalt source and take it out after reaching an absorbed dose of 12 kGy; prepare a 35% mass concentration of glycidyl methacrylate / chlorobenzene solution, introduce nitrogen for 30 minutes, use benzoyl peroxide as an initiator, soak the polytetrafluoroethylene membrane in the glycidyl methacrylate / chlorobenzene solution at a bath ratio of 1:12, heat to 85°C and react for 5 hours; wash with acetone and dry; Step 2: S21: Allylamine is dispersed in tetrahydrofuran, and 1,1,3,3-tetramethyldisiloxane is added under nitrogen atmosphere using an isopropanol solution of chloroplatinic acid as a catalyst, and the temperature is raised to 65°C for reaction for 6 hours; after the solvent is evaporated under reduced pressure, the mixture is washed with methanol and dried to obtain amino-terminated tetramethyldisiloxane; the molar ratio of allyl group to 1,1,3,3-tetramethyldisiloxane is 1:1; S22: dispersing terminal aminotetramethyldisiloxane and biphenyltetracarboxylic acid dianhydride in N-methylpyrrolidone in a molar ratio of 1.2:1, reacting for 7 hours under a nitrogen environment, heating to 75° C., adding trimellitic anhydride for end-capping and reacting for 2.5 hours to obtain a carboxyl-terminated silicon-containing polyimide; S23: by weight percentage, 15% of carboxyl-terminated silicon-containing polyimide and 85% of epoxy resin were mixed to obtain a modified epoxy resin; 100 g of the modified epoxy resin, 53 g of a curing agent, 25 g of nano-silicon carbide, 11 g of a silane coupling agent, and 3.8 g of an antioxidant were mixed to obtain an epoxy resin glue; Step 3: The surface of the silver-plated copper conductor core is coated with a polytetrafluoroethylene film in S12 and an epoxy resin glue with a coating thickness of 80 μm, and cured at 100° C. to obtain an insulating layer; a silver film is attached to the surface of the insulating layer to form a shielding layer; and a PFA sheath is coated on the surface of the shielding layer to obtain a product.

[0022] Embodiment 3: A polytetrafluoroethylene insulated cable and a preparation process thereof, comprising the following steps: Step 1: Preparation of polytetrafluoroethylene membrane: S11: 100 g of polytetrafluoroethylene resin and 18 g of auxiliary oil were mixed, left to stand for aging for 30 h, and blanked at 3 MPa; the blank was extruded into strips, and after calendering and stretching, it was shaped at 400° C. to obtain a polytetrafluoroethylene film with a thickness of 0.3 mm; S12: Place the polytetrafluoroethylene membrane in an aerobic environment. 60 Pre-irradiate in a Co cobalt source and take it out after reaching an absorbed dose of 15 kGy; prepare a 35% mass concentration of glycidyl methacrylate / chlorobenzene solution, pass nitrogen for 30 minutes, use benzoyl peroxide as an initiator, soak the polytetrafluoroethylene membrane in the glycidyl methacrylate / chlorobenzene solution at a bath ratio of 1:15, heat to 90°C and react for 6 hours; wash with acetone and dry; Step 2: S21: Allylamine is dispersed in tetrahydrofuran, and 1,1,3,3-tetramethyldisiloxane is added in a nitrogen environment using an isopropanol solution of chloroplatinic acid as a catalyst, and the temperature is raised to 70°C for reaction for 8 hours; after the solvent is evaporated under reduced pressure, the terminal aminotetramethyldisiloxane is obtained by washing with methanol and drying; the molar ratio of allyl group to 1,1,3,3-tetramethyldisiloxane is 1:1; S22: dispersing terminal aminotetramethyldisiloxane and biphenyltetracarboxylic acid dianhydride in N-methylpyrrolidone in a molar ratio of 1.2:1, reacting for 8 hours under a nitrogen environment, heating to 80° C., adding trimellitic anhydride for end-capping and reacting for 3 hours to obtain a carboxyl-terminated silicon-containing polyimide; S23: by weight percentage, 18% of carboxyl-terminated silicon-containing polyimide and 82% of epoxy resin are mixed to obtain a modified epoxy resin; 100 g of the modified epoxy resin, 53 g of a curing agent, 25 g of nano-silicon carbide, 11 g of a silane coupling agent, and 3.8 g of an antioxidant are mixed to obtain an epoxy resin glue; Step 3: The surface of the silver-plated copper conductor core is coated with a polytetrafluoroethylene film in S12 and an epoxy resin glue with a coating thickness of 80 μm, and cured at 100° C. to obtain an insulating layer; a silver film is attached to the surface of the insulating layer to form a shielding layer; and a PFA sheath is coated on the surface of the shielding layer to obtain a product.

[0023] Comparative Example 1: No epoxy group was grafted onto the polytetrafluoroethylene membrane, and other parameters were the same as those in Example 1.

[0024] Step 1: Preparation of polytetrafluoroethylene membrane: 100g of polytetrafluoroethylene resin and 18g of auxiliary oil were mixed, left to stand for aging for 24h, and then blanked at 2MPa; the blank was extruded into strips, and after calendering and stretching, it was shaped at 300°C to obtain a polytetrafluoroethylene film with a thickness of 0.3mm; Step 2: S21: Allylamine is dispersed in tetrahydrofuran, and 1,1,3,3-tetramethyldisiloxane is added in a nitrogen environment using an isopropanol solution of chloroplatinic acid as a catalyst, and the temperature is raised to 60°C for reaction for 5 hours; after the solvent is evaporated under reduced pressure, the terminal aminotetramethyldisiloxane is obtained by washing with methanol and drying; the molar ratio of allyl group to 1,1,3,3-tetramethyldisiloxane is 1:1; S22: dispersing terminal aminotetramethyldisiloxane and biphenyltetracarboxylic acid dianhydride in N-methylpyrrolidone in a molar ratio of 1.2:1, reacting for 6 hours under a nitrogen environment, heating to 70° C., adding trimellitic anhydride for end-capping and reacting for 2 hours to obtain a carboxyl-terminated silicon-containing polyimide; S23: By weight percentage, 10% of carboxyl-terminated silicon-containing polyimide and 90% of epoxy resin are mixed to obtain a modified epoxy resin; 100 g of the modified epoxy resin, 53 g of a curing agent, 25 g of nano-silicon carbide, 11 g of a silane coupling agent, and 3.8 g of an antioxidant are mixed to obtain an epoxy resin glue; Step 3: The surface of the silver-plated copper conductor core is coated with a polytetrafluoroethylene film in S12 and an epoxy resin glue with a coating thickness of 80 μm, and cured at 100° C. to obtain an insulating layer; a silver film is attached to the surface of the insulating layer to form a shielding layer; and a PFA sheath is coated on the surface of the shielding layer to obtain a product.

[0025] Comparative Example 2: No carboxyl-terminated silicon-containing polyimide was added, and the other parameters were the same as those in Example 2.

[0026] Step 1: Preparation of polytetrafluoroethylene membrane: S11: 100 g of polytetrafluoroethylene resin and 18 g of auxiliary oil were mixed, left to stand for aging for 27 h, and blanked at 2.5 MPa; the blank was extruded into strips, and after calendering and stretching, it was shaped at 350° C. to obtain a polytetrafluoroethylene film with a thickness of 0.3 mm; S12: Place the polytetrafluoroethylene membrane in an aerobic environment. 60 Pre-irradiate in a Co cobalt source and take it out after reaching an absorbed dose of 12 kGy; prepare a 35% mass concentration of glycidyl methacrylate / chlorobenzene solution, introduce nitrogen for 30 minutes, use benzoyl peroxide as an initiator, soak the polytetrafluoroethylene membrane in the glycidyl methacrylate / chlorobenzene solution at a bath ratio of 1:12, heat to 85°C and react for 5 hours; wash with acetone and dry; Step 2: 100 g of modified epoxy resin, 53 g of curing agent, 25 g of nano silicon carbide, 11 g of silane coupling agent, and 3.8 g of antioxidant were mixed to obtain epoxy resin glue; Step 3: The surface of the silver-plated copper conductor core is coated with a polytetrafluoroethylene film in S12 and an epoxy resin glue with a coating thickness of 80 μm, and cured at 100° C. to obtain an insulating layer; a silver film is attached to the surface of the insulating layer to form a shielding layer; and a PFA sheath is coated on the surface of the shielding layer to obtain a product.

[0027] Comparative Example 3: The amount of the terminal carboxyl silicon-containing polyimide in the modified epoxy resin was increased, and the other parameters were the same as those in Example 3.

[0028] Step 1: Preparation of polytetrafluoroethylene membrane: S11: 100 g of polytetrafluoroethylene resin and 18 g of auxiliary oil were mixed, left to stand for aging for 30 h, and blanked at 3 MPa; the blank was extruded into strips, and after calendering and stretching, it was shaped at 400° C. to obtain a polytetrafluoroethylene film with a thickness of 0.3 mm; S12: Place the polytetrafluoroethylene membrane in an aerobic environment. 60 Pre-irradiate in a Co cobalt source and take it out after reaching an absorbed dose of 15 kGy; prepare a 35% mass concentration of glycidyl methacrylate / chlorobenzene solution, pass nitrogen for 30 minutes, use benzoyl peroxide as an initiator, soak the polytetrafluoroethylene membrane in the glycidyl methacrylate / chlorobenzene solution at a bath ratio of 1:15, heat to 90°C and react for 6 hours; wash with acetone and dry; Step 2: S21: Allylamine is dispersed in tetrahydrofuran, and 1,1,3,3-tetramethyldisiloxane is added in a nitrogen environment using an isopropanol solution of chloroplatinic acid as a catalyst, and the temperature is raised to 70°C for reaction for 8 hours; after the solvent is evaporated under reduced pressure, the terminal aminotetramethyldisiloxane is obtained by washing with methanol and drying; the molar ratio of allyl group to 1,1,3,3-tetramethyldisiloxane is 1:1; S22: dispersing terminal aminotetramethyldisiloxane and biphenyltetracarboxylic acid dianhydride in N-methylpyrrolidone in a molar ratio of 1.2:1, reacting for 8 hours under a nitrogen environment, heating to 80° C., adding trimellitic anhydride for end-capping and reacting for 3 hours to obtain a carboxyl-terminated silicon-containing polyimide; S23: By weight percentage, 30% of carboxyl-terminated silicon-containing polyimide and 70% of epoxy resin are mixed to obtain a modified epoxy resin; 100 g of the modified epoxy resin, 53 g of a curing agent, 25 g of nano-silicon carbide, 11 g of a silane coupling agent, and 3.8 g of an antioxidant are mixed to obtain an epoxy resin glue; Step 3: The surface of the silver-plated copper conductor core is coated with a polytetrafluoroethylene film in S12 and an epoxy resin glue with a coating thickness of 80 μm, and cured at 100° C. to obtain an insulating layer; a silver film is attached to the surface of the insulating layer to form a shielding layer; and a PFA sheath is coated on the surface of the shielding layer to obtain a product.

[0029] Experiment: The polytetrafluoroethylene insulation layers prepared in Examples 1 to 3 and Comparative Examples 1 to 3 were tested. The test method is as follows.

[0030] Bending test: Wrap the conductor covered with polytetrafluoroethylene insulation layer on a curved cylinder with a diameter of 13mm for 3 turns. After 1 minute, remove it from the curved cylinder, straighten it and observe whether the surface coating has cracks.

[0031] Salt resistance: The test temperature is 25℃. Put the conductor covered with polytetrafluoroethylene insulation layer into 4g / L sodium chloride solution and soak it for one month to observe whether the surface is bubbling or damaged.

[0032] Contact angle test: A contact angle meter was used for the test, distilled water was selected as the test liquid, and the droplet volume was set to 4 μL.

[0033] Wear-resistant experiment: A friction tester was used for friction testing. The material of the friction pair was 45# carbon steel (AISI 1045), the Rockwell hardness was 45, the surface roughness was 0.4, the outer diameter was 40×10mm, and the inner diameter was 16×10mm. Before the test, the friction pair was polished with 1000-mesh metallographic sandpaper and then cleaned with anhydrous alcohol. The friction load mass was 5kg, the friction speed was 100rpm / min, and the friction time was 10min. The weight loss before and after friction was calculated, which was the wear amount.

[0034] The experimental results are shown in Table 1 below.

[0035] Table 1. Test results of various properties of polytetrafluoroethylene insulation layer

[0036] Conclusion: The data of Examples 1 to 3 and Comparative Examples 1 to 3 show that the polytetrafluoroethylene insulated cables prepared by the present invention have good performance. The data of Example 1 and Comparative Example 1 show that the adhesion between the polytetrafluoroethylene film and the epoxy resin coating can be effectively improved by modifying the surface of the polytetrafluoroethylene film, and the bonding force between the two is better, and the film does not fall off or bubble after being soaked in salt water; under the action of external force, the sliding friction between the epoxy resin coating and the polytetrafluoroethylene film layer is relatively smaller, so the wear amount is low; the data of Example 2 and Comparative Example 2 show that after adding the carboxyl-terminated silicon-containing polyimide, the epoxy resin coating has better toughness, improved hydrophobicity, and improved tolerance to salt ions; the data of Example 3 and Comparative Example 3 show that when the content of the carboxyl-terminated silicon-containing polyimide is too high, its compatibility with the epoxy resin is reduced, and the performance of the polytetrafluoroethylene insulation layer is reduced.

[0037] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a polytetrafluoroethylene insulated cable, characterized in that: The following steps are involved: The surface of the silver-plated copper conductor core is coated with a polytetrafluoroethylene film and an epoxy resin glue with a coating thickness of 50-80 μm, and cured at 100-120° C. to obtain an insulating layer; a silver film is attached to the surface of the insulating layer to form a shielding layer; and a PFA sheath is coated on the surface of the shielding layer to obtain a product; The preparation method of the polytetrafluoroethylene film is: S1: Mix polytetrafluoroethylene resin and auxiliary oil, and then prepare blanks after standing and aging; extrude the blanks into strips, and then shape them after calendering and stretching to obtain a polytetrafluoroethylene film with a thickness of 0.2-0.3 mm; S2: Place the polytetrafluoroethylene membrane in an aerobic environment 60 Pre-irradiate in a Co cobalt source and take it out after reaching an absorbed dose of 8~15kGy; prepare a 35~40% mass concentration of glycidyl methacrylate / chlorobenzene solution, pass nitrogen for 30 minutes, use benzoyl peroxide as an initiator, soak the polytetrafluoroethylene membrane in the glycidyl methacrylate / chlorobenzene solution, raise the temperature to 80~90℃ and react for 4~6h; wash with acetone and dry.

2. The method for preparing a polytetrafluoroethylene insulated cable according to claim 1, characterized in that: In S1, 100 parts of polytetrafluoroethylene resin and 15 to 20 parts of auxiliary oil are mixed by weight.

3. The method for preparing a polytetrafluoroethylene insulated cable according to claim 1, characterized in that: In S1, the aging time is 24~30h; the billet pressure is 2~3Mpa; and the shaping temperature is 300~400℃.

4. The method for preparing a polytetrafluoroethylene insulated cable according to claim 1, characterized in that: In S2, the polytetrafluoroethylene membrane is immersed in a glycidyl methacrylate / chlorobenzene solution at a bath ratio of 1:(10-15).

5. The method for preparing a polytetrafluoroethylene insulated cable according to claim 1, characterized in that: The preparation method of epoxy resin glue is as follows: terminal carboxyl silicon-containing polyimide and epoxy resin are mixed to obtain modified epoxy resin; by weight, 100 parts of modified epoxy resin, 46-57 parts of curing agent, 18-25 parts of nano silicon carbide, 10-12 parts of silane coupling agent and 3-5 parts of antioxidant are mixed to obtain epoxy resin glue.

6. The method for preparing a polytetrafluoroethylene insulated cable according to claim 1, characterized in that: In the modified epoxy resin, by weight percentage, 10-18% of the carboxyl-terminated silicon-containing polyimide and 82-90% of the epoxy resin.

7. The method for preparing a polytetrafluoroethylene insulated cable according to claim 5, characterized in that: The preparation method of carboxyl-terminated silicon-containing polyimide comprises the following steps: a. Allylamine is dispersed in tetrahydrofuran, and 1,1,3,3-tetramethyldisiloxane is added under nitrogen atmosphere with isopropanol solution of chloroplatinic acid as catalyst, and the temperature is raised to 60-70°C for reaction for 5-8h; after the solvent is evaporated under reduced pressure, the mixture is washed with methanol and dried to obtain amino-terminated tetramethyldisiloxane; b. Disperse terminal aminotetramethyldisiloxane and biphenyltetracarboxylic acid dianhydride in N-methylpyrrolidone, react for 6-8 hours under nitrogen environment, heat to 70-80°C, add trimellitic anhydride for end-capping reaction for 2-3 hours, and obtain terminal carboxyl silicon-containing polyimide.

8. The method for preparing a polytetrafluoroethylene insulated cable according to claim 5, characterized in that: In step a, the molar ratio of allyl group to 1,1,3,3-tetramethyldisiloxane is 1:

1.

9. The method for preparing a polytetrafluoroethylene insulated cable according to claim 5, characterized in that: In step b, the molar ratio of amino-terminated tetramethyl disiloxane to biphenyltetracarboxylic dianhydride is (1.2-1.5):

1.

10. A polytetrafluoroethylene insulated cable prepared by the preparation method according to any one of claims 1 to 9.

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