A conductive low-exudation polyamide composition, its preparation method and application

Abstract

This invention relates to a conductive low-exudation polyamide composition, its preparation method, and its application. The conductive low-exudation polyamide composition is prepared from the following components in parts by weight: 35-65 parts polyamide resin, 20-50 parts carbon nanotube masterbatch, 1-20 parts toughening agent, and 0.1-2 parts antioxidant. The carbon nanotube masterbatch is prepared by coating carbon nanotubes with polyether block amide as a carrier. This invention adds carbon nanotube masterbatch coated with polyether block amide as a carrier to pre-disperse the carbon nanotubes. On the one hand, polyether block amide has excellent compatibility with long-chain polyamides, allowing the carbon nanotubes to be well dispersed in the matrix phase. On the other hand, polyether block amide itself has good antistatic properties, and it can have a good conductive synergistic effect with carbon nanotubes, ensuring that the conductivity of the polyamide composition does not change over time or with environmental factors, maintaining good conductivity over a long period.

Description

Technical Field

[0001] This invention relates to the field of polymer composite materials technology, and in particular to a conductive low-exudation polyamide composite, its preparation method, and its application. Background Technology

[0002] Polyamide resin, commonly known as nylon (PA), has excellent comprehensive properties such as good mechanical properties, good barrier properties, high heat resistance, high wear resistance, and high chemical corrosion resistance. It is widely used in machinery manufacturing, power tools, electronics and electrical appliances, and transportation.

[0003] PA12 and PA11 are widely used in the manufacture of automotive fuel lines due to their excellent properties such as high strength, low water absorption, good low-temperature toughness, and resistance to fuel, acids, and alkalis. However, since PA12 and PA11 are typically produced through the ring-opening polymerization of lactams, a large amount of monomer residue remains after polymerization. When used in fuel lines, this residual monomer gradually precipitates under the influence of fuel, potentially clogging fuel injectors. Furthermore, to reduce the risk of static electricity generated by friction between the fuel line and connectors, and between the fuel line and fuel during vehicle operation, the fuel line material needs to possess antistatic properties.

[0004] Currently, the most common method to improve the antistatic properties of polyamide materials is to add conductive fillers such as metal fibers, carbon fibers, carbon black, and carbon nanotubes. However, the application of metal fibers and carbon fibers is limited by their high addition amount, high price, and large fluctuations in surface resistivity. Carbon black, due to its low conductivity, requires large additions and can easily lead to a decrease in the physical and mechanical properties and flow properties of nylon resin. Carbon nanotubes, on the other hand, are one-dimensional nanomaterials with excellent mechanical properties and conductivity. They are currently mainly used to replace carbon black to improve the antistatic properties of polyamides. They have advantages such as low addition amount, acceptable cost, minimal impact on the physical and mechanical properties of polyamides, and even slight enhancement within a certain range. Moreover, their surface resistivity is relatively more stable. However, due to their large specific surface area, carbon nanotubes are very difficult to disperse when used for polyamide modification, reducing their effectiveness as conductive fillers and antistatic agents. Therefore, improving the compatibility between carbon nanotubes and polyamides is key to further improving the performance of conductive composite materials. Summary of the Invention

[0005] Based on this, and addressing the technical problem that carbon nanotubes, due to their large specific surface area, are very difficult to disperse when used for polyamide modification, thus reducing the effectiveness of carbon nanotubes as conductive fillers and antistatic agents, the purpose of this invention is to provide a conductive low-precipitation polyamide composition, its preparation method, and its application. This conductive low-precipitation polyamide composition has the characteristics of low precipitation and long-term maintenance of conductivity.

[0006] To achieve the above objectives, the present invention adopts the following technical solution.

[0007] This invention provides a conductive low-exudation polyamide polymer, which is prepared from the following components in parts by weight: 35-65 parts polyamide resin, 20-50 parts carbon nanotube masterbatch, 1-20 parts toughening agent, and 0.1-2 parts antioxidant; wherein the carbon nanotube masterbatch is a masterbatch obtained by loading carbon nanotubes onto a polyether block amide as a carrier.

[0008] This invention adds carbon nanotube masterbatch coated with carbon nanotubes using polyether block amide as a carrier to pre-disperse the carbon nanotubes. On the one hand, polyether block amide has excellent compatibility with long-chain polyamides, allowing the carbon nanotubes to be well dispersed in the matrix phase. On the other hand, polyether block amide itself has good antistatic properties and can have a good conductive synergistic effect with carbon nanotubes, ensuring that the conductivity of the polyamide composition does not change over time or with the environment, and can maintain good conductivity for a long time. This solves the technical problem that carbon nanotubes are very difficult to disperse when used for polyamide modification due to their large specific surface area, which reduces the effectiveness of carbon nanotubes as conductive fillers and antistatic agents.

[0009] As a further improvement to the above scheme, the polyamide resin comprises, by weight, 30-60 parts of medium-viscosity long-chain polyamide resin and 5-30 parts of low-viscosity long-chain polyamide resin.

[0010] As a further improvement to the above scheme, the medium-viscosity long-chain polyamide resin is at least one of PA612 and PA1012, and its relative viscosity is 2.0-2.8.

[0011] As a further improvement to the above scheme, the low-viscosity long-chain polyamide resin is at least one of PA612 and PA1012, and its relative viscosity is 1.5-2.0 (excluding 2.0).

[0012] As a further improvement to the above scheme, the polyether block amide uses polyamide as the hard segment and polyether as the soft segment;

[0013] And / or, in the carbon nanotube masterbatch, the mass of the carbon nanotubes is 5%-15% of the total mass of the carbon nanotube masterbatch.

[0014] As a further improvement to the above scheme, the preparation process of the carbon nanotube masterbatch is as follows: polyamide and polyetheramine are mixed and polymerized to obtain medium-low viscosity polyether block amide; carbon nanotube particles are added to the medium-low viscosity polyether block amide and stirred and dispersed evenly, and then granulated underwater and dried to obtain the carbon nanotube masterbatch.

[0015] As a further improvement to the above scheme, the polyamide is a carboxyl-terminated polyamide prepolymer, and the polyetheramine is a polyethylene glycol etheramine; preferably, the carboxyl-terminated polyamide prepolymer is at least one of PA612 and PA1012.

[0016] And / or, the polymerization reaction process is as follows: polyamide and polyetheramine are added to the polymerization reactor and heated to 240°C. The reaction is first carried out under normal pressure and nitrogen purging for 3 hours, and then vacuumed under 500Pa pressure for 2 hours.

[0017] As a further improvement to the above solution, the polyethylene glycol etheramine (PEG-based polyetheramine) includes, but is not limited to, Huntsman Corporation of the United States. RE-2000 RE-900.

[0018] As a further improvement to the above scheme, the toughening agent is at least one of maleic anhydride-grafted ethylene-octene, maleic anhydride-grafted ethylene-butene copolymer elastomer POE-g-MA, maleic anhydride-grafted styrene-ethylene-butene-styrene block copolymer SEBS-g-MA, and maleic anhydride-grafted ethylene propylene diene monomer (EPDM) rubber-g-MA.

[0019] As a further improvement to the above scheme, the antioxidant is at least one of antioxidant 1098, antioxidant 245, and antioxidant 168.

[0020] The present invention also provides a method for preparing the conductive low-precipitation polyamide composition as described above, comprising the following steps: mixing polyamide resin, carbon nanotube masterbatch, toughening agent and antioxidant evenly, and granulating by a twin-screw extruder to obtain the conductive low-precipitation polyamide composition.

[0021] As a further improvement to the above scheme, the temperature of the twin-screw extruder is 10°C-30°C higher than the melting point of the polyamide resin.

[0022] As a further improvement to the above scheme, the temperature of each zone of the twin-screw extruder is set as follows: the temperature of zone one is 160℃-220℃, and the temperature of other zones and the die head is 220℃-260℃; the main rotation speed of the twin-screw extruder is 50-1500r / min.

[0023] The present invention also proposes the application of the conductive low-exudation polyamide composition as described above in a conductive fuel line.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] 1. The carbon nanotube masterbatch of the present invention is a masterbatch obtained by loading carbon nanotubes onto polyether block amide as a carrier. The carbon nanotubes are pre-dispersed, and the polyether block amide coats the carbon nanotubes. The polyether block amide has excellent compatibility with long-chain polyamide, so that the loaded carbon nanotubes can be well dispersed in the matrix phase. When using twin-screw modified granulation, there is no need to select a special screw aspect ratio or a special dispersion process for dispersing carbon nanotubes, which greatly reduces the difficulty of using carbon nanotubes. At the same time, the polyether block amide itself has good antistatic properties, and the polyether block amide and carbon nanotubes have a good conductive synergistic effect, so that the conductivity of the polyamide composition product will not change with time and environment, and can maintain good conductivity for a long time.

[0026] 2. In the process of producing polyether block amide through the polymerization reaction of polyamide and polyetheramine, carbon nanotube particles are added. As the viscosity of the polyether block amide increases, the carbon nanotubes are dispersed at the molecular level. The carbon nanotubes can be uniformly dispersed in the polyether block amide to obtain carbon nanotube masterbatch. When the carbon nanotube masterbatch is used to modify and produce low-precipitation conductive polyamide compositions, the problem of difficult dispersion of carbon nanotubes is avoided, thereby improving the surface smoothness of the extruded pipes and other products, and thus improving the fluid flow rate of the pipeline.

[0027] 3. This invention uses polycondensation polyamide PA612 and PA1012 resins as base materials. PA612 and PA1012 resins have low monomer residue. Combined with carbon nanotubes with strong adsorption capacity, the risk of residual monomer precipitation is avoided. It is very suitable for applications such as conductive inner layer of multilayer fuel pipes and single-layer conductive fuel pipes.

[0028] 4. The present invention uses medium-viscosity polyamide PA612 and PA1012 resins as base materials, which ensures that the composition has high elongation at break and good impact performance.

[0029] 5. The present invention adds low-viscosity polyamide PA612 and PA1012 resins, which improves the flow properties of the composition and avoids the problem of the composition being too viscous and difficult to extrude.

[0030] 6. The surface resistivity of the conductive, low-deposition polyamide composition of the present invention is 10 Ω·cm. 2 -10 4 Ω has excellent electrical conductivity, and the material has an elongation at break of ≥40% and good toughness. Detailed Implementation

[0031] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] The specific information of the raw materials used in the following examples and comparative examples is as follows:

[0033] (1) Medium-viscosity long-chain carbon amide resin

[0034] Medium viscosity PA612, grade HB30, relative viscosity 2.8, manufactured by Huitong New Materials Co., Ltd.

[0035] Medium viscosity PA1012, grade PA1012-II, relative viscosity 2.0, manufactured by Shandong Dongchen Ruisen.

[0036] (2) Low-viscosity long-chain polyamide resin

[0037] Low viscosity PA612, grade HB10, relative viscosity 1.5, manufactured by Huitong New Materials Co., Ltd.

[0038] The low-viscosity PA1012, grade HD10, has a relative viscosity of 1.9 and is manufactured by Huitong New Materials Co., Ltd.

[0039] (3) Toughening agent

[0040] SEBS-g-MA, grade FG1924, is manufactured by Kraton.

[0041] EPDM-g-MA, grade VA1803, is manufactured by Exxon.

[0042] POE-g-MA, brand name KT-V25, is manufactured by Shenyang Ketong.

[0043] (4) Multi-walled carbon nanotubes

[0044] The multi-walled carbon nanotube LG LUCAN BT1001M is manufactured by LG Chem in South Korea.

[0045] GT-300 multi-walled carbon nanotubes are manufactured by Shandong Dazhan Nanomaterials Co., Ltd.

[0046] (5) Polyethylene glycol etheramine (PEG-based polyetheramine) RE-2000 The RE-900 is manufactured by Huntsman in the United States.

[0047] All other materials not shown are commercially available, commonly used products.

[0048] It is understood that the above-mentioned raw materials and reagents are merely examples of some specific embodiments of the present invention, making the technical solution of the present invention clearer, and do not mean that the present invention can only use the above-mentioned reagents. The specific scope shall be determined by the claims. In addition, unless otherwise specified, "parts" in the examples and comparative examples refer to parts by weight.

[0049] Any range described in this invention includes the endpoint, any value between the endpoints, and any subrange consisting of the endpoint or any value between the endpoints.

[0050] Example 1

[0051] This embodiment proposes a conductive low-exudation polyamide composition, the preparation method of which includes the following two steps.

[0052] Step 1: Preparation of carbon nanotube masterbatch: PA612 prepolymer and polyetheramine in a weight ratio of 2:3. RE-2000 was added to the polymerization reactor, heated to 240℃, and purged with nitrogen at normal pressure for 3 hours. Then, the reaction was carried out under vacuum for 2 hours at a pressure below 500Pa to obtain medium-low viscosity polyether amide. Then, 10% by weight of multi-walled carbon nanotubes LG LUCAN BT1001M was added to the polymerization reactor, stirred at a uniform speed for 1 hour, and then stretched, granulated, and dried by a melt pump to obtain carbon nanotube masterbatch a.

[0053] Step 2: Preparation of conductive low-exudation polyamide composition: 34.4 kg of medium-viscosity PA612 through HB30, 30 kg of low-viscosity PA612 through HB10, 30 kg of carbon nanotube masterbatch a prepared in Step 1, 5 kg of toughening agent SEBS-g-MA, 0.3 kg of antioxidant 1098, and 0.3 kg of antioxidant 168 are added to a high-speed mixer and mixed evenly. Then, the mixture is granulated using a twin-screw extruder to obtain polyamide composition A.

[0054] In step two, the temperatures of each zone of the twin-screw extruder are set as follows: Zone 1: 160-220℃; Zone 2: 220-260℃; Zone 3: 220-260℃; Zone 4: 220-260℃; Zone 5: 220-260℃; Zone 6: 220-260℃; Zone 7: 220-260℃; Zone 8: 220-260℃; Zone 9: 220-260℃; Zone 10: 220-260℃; the die head temperature of the twin-screw extruder is 220-260℃; and the main engine speed of the twin-screw extruder is 50-1500 r / min.

[0055] After drying, the polyamide composition A prepared in this embodiment was injection molded at 250°C to test its mechanical properties using GB / T1040-2018 type 1A tensile specimens and GB / T1043-2018 simply supported beam impact specimens; simultaneously, it was extruded to obtain... Observe the surface condition of the flexible tube (outer diameter 8mm, wall thickness 1mm), and test the surface resistance and precipitate content.

[0056] Example 2

[0057] This embodiment proposes a conductive low-exudation polyamide composition, the preparation method of which includes the following two steps.

[0058] Step 1: Preparation of carbon nanotube masterbatch: PA1012 prepolymer and polyetheramine in a weight ratio of 1:2 RE-900 was added to the polymerization reactor, heated to 240℃, and purged with nitrogen at normal pressure for 3 hours. Then, the reaction was carried out under vacuum for 2 hours at a pressure below 500Pa to obtain medium-low viscosity polyether amide. Then, 15% by weight of multi-walled carbon nanotubes LG LUCAN BT1001M was added to the polymerization reactor, stirred at a uniform speed for 1 hour, and then stretched, granulated, and dried by a melt pump to obtain carbon nanotube masterbatch b.

[0059] Step 2: Preparation of conductive low-exudation polyamide composition: 59.4 kg of medium-viscosity polyamide 612 through HB30, 15.5 kg of low-viscosity PA612 through HB10, 24 kg of carbon nanotube masterbatch b prepared in Step 1, 1 kg of toughening agent EPDM-g-MA, and 0.1 kg of antioxidant 1098 are put into a high-speed mixer and mixed evenly. Then, the mixture is granulated using a twin-screw extruder to obtain polyamide composition B.

[0060] In step two, the temperatures of each zone of the twin-screw extruder are set as follows: Zone 1: 160-220℃; Zone 2: 220-260℃; Zone 3: 220-260℃; Zone 4: 220-260℃; Zone 5: 220-260℃; Zone 6: 220-260℃; Zone 7: 220-260℃; Zone 8: 220-260℃; Zone 9: 220-260℃; Zone 10: 220-260℃; the die head temperature of the twin-screw extruder is 220-260℃; and the main engine speed of the twin-screw extruder is 50-1500 r / min.

[0061] After drying, the polyamide composition B prepared in this embodiment was injection molded at 250°C using GB / T1040-2018 type 1A tensile specimens and GB / T1043-2018 simply supported beam impact specimens to test its mechanical properties; simultaneously, it was extruded to obtain... Observe the surface condition of the flexible tube (outer diameter 8mm, wall thickness 1mm), and test the surface resistance and precipitate content.

[0062] Example 3

[0063] This embodiment proposes a conductive low-exudation polyamide composition, the preparation method of which includes the following two steps.

[0064] Step 1: Preparation of carbon nanotube masterbatch: PA1012 prepolymer and polyetheramine in a weight ratio of 2:1 RE-2000 was added to the polymerization reactor, heated to 240℃, and purged with nitrogen at normal pressure for 3 hours. Then, the reaction was carried out under vacuum for 2 hours at a pressure below 500Pa to obtain medium-low viscosity polyether amide. Then, 5% by weight of multi-walled carbon nanotubes LG LUCAN BT1001M was added to the polymerization reactor, stirred at a uniform speed for 1 hour, and then stretched, granulated, and dried by a melt pump to obtain carbon nanotube masterbatch c.

[0065] Step 2: Preparation of conductive low-exudation polyamide composition: 43 kg of Dongchen medium viscosity PA1012-II, 10 kg of low viscosity PA1012 Huitong HD10, 40 kg of carbon nanotube masterbatch c prepared in Step 1, 5 kg of toughening agent EPDM-g-MA, 1.5 kg of antioxidant 245, and 0.5 kg of antioxidant 168 are added to a high-speed mixer and mixed evenly. Then, the mixture is granulated using a twin-screw extruder to obtain polyamide composition C.

[0066] In step two, the temperatures of each zone of the twin-screw extruder are set as follows: Zone 1: 160-220℃; Zone 2: 220-260℃; Zone 3: 220-260℃; Zone 4: 220-260℃; Zone 5: 220-260℃; Zone 6: 220-260℃; Zone 7: 220-260℃; Zone 8: 220-260℃; Zone 9: 220-260℃; Zone 10: 220-260℃; the die head temperature of the twin-screw extruder is 220-260℃; and the main engine speed of the twin-screw extruder is 50-1500 r / min.

[0067] After drying, the polyamide composition C prepared in this embodiment was injection molded at 250°C to test its mechanical properties using GB / T1040-2018 type 1A tensile specimens and GB / T1043-2018 simply supported beam impact specimens; simultaneously, it was extruded to obtain... Observe the surface condition of the flexible tube (outer diameter 8mm, wall thickness 1mm), and test the surface resistance and precipitate content.

[0068] Example 4

[0069] This embodiment proposes a conductive low-exudation polyamide composition, the preparation method of which includes the following two steps.

[0070] Step 1: Preparation of carbon nanotube masterbatch: PA612 prepolymer and polyetheramine in a weight ratio of 3:2 RE-900 was added to the polymerization reactor, heated to 240℃, and purged with nitrogen at normal pressure for 3 hours. Then, the reaction was carried out under vacuum for 2 hours at a pressure below 500Pa to obtain medium-low viscosity polyether amide. Then, 12% by weight of multi-walled carbon nanotubes LG LUCAN BT1001M was added to the polymerization reactor, stirred at a uniform speed for 1 hour, and then stretched, granulated, and dried by a melt pump to obtain carbon nanotube masterbatch d.

[0071] Step 2: Preparation of conductive low-exudation polyamide composition: 42.9 kg of medium-viscosity PA612 with HB30, 17 kg of low-viscosity PA1012 with HD10, 20 kg of carbon nanotube masterbatch d prepared in Step 1, 20 kg of toughening agent POE-g-MA, and 0.1 kg of antioxidant 168 are put into a high-speed mixer and mixed evenly. Then, the mixture is granulated using a twin-screw extruder to obtain polyamide composition D.

[0072] In step two, the temperatures of each zone of the twin-screw extruder are set as follows: Zone 1: 160-220℃; Zone 2: 220-260℃; Zone 3: 220-260℃; Zone 4: 220-260℃; Zone 5: 220-260℃; Zone 6: 220-260℃; Zone 7: 220-260℃; Zone 8: 220-260℃; Zone 9: 220-260℃; Zone 10: 220-260℃; the die head temperature of the twin-screw extruder is 220-260℃; and the main engine speed of the twin-screw extruder is 50-1500 r / min.

[0073] After drying, the polyamide composition D prepared in this embodiment was injection molded at 250°C using GB / T1040-2018 type 1A tensile specimens and GB / T1043-2018 simply supported beam impact specimens to test its mechanical properties; simultaneously, it was extruded to obtain... Observe the surface condition of the flexible tube (outer diameter 8mm, wall thickness 1mm), and test the surface resistance and precipitate content.

[0074] Example 5

[0075] This embodiment proposes a conductive low-exudation polyamide composition, the preparation method of which includes the following two steps.

[0076] Step 1: Preparation of nanotube masterbatch: PA1012 prepolymer and polyetheramine in a weight ratio of 1:2 RE-2000 was added to the polymerization reactor, heated to 240℃, and purged with nitrogen at normal pressure for 3 hours. Then, the reaction was carried out under vacuum for 2 hours at a pressure below 500Pa to obtain medium-low viscosity polyether amide. Then, 7% by weight of multi-walled carbon nanotubes GT-300 was added to the polymerization reactor, stirred at a uniform speed for 1 hour, and then stretched, granulated, and dried by a melt pump to obtain carbon nanotube masterbatch e.

[0077] Step 2: Preparation of conductive low-exudation polyamide composition: 30 kg of medium-viscosity PA612 through HB30, 5 kg of low-viscosity PA612 through HB10, 50 kg of nanotube masterbatch e prepared in Step 1, 14.4 kg of toughening agent SEBS-g-MA, 0.3 kg of antioxidant 1098, and 0.3 kg of antioxidant 168 are added to a high-speed mixer and mixed evenly. Then, the mixture is granulated using a twin-screw extruder to obtain polyamide composition E.

[0078] In step two, the temperatures of each zone of the twin-screw extruder are set as follows: Zone 1: 160-220℃; Zone 2: 220-260℃; Zone 3: 220-260℃; Zone 4: 220-260℃; Zone 5: 220-260℃; Zone 6: 220-260℃; Zone 7: 220-260℃; Zone 8: 220-260℃; Zone 9: 220-260℃; Zone 10: 220-260℃; the die head temperature of the twin-screw extruder is 220-260℃; and the main engine speed of the twin-screw extruder is 50-1500 r / min.

[0079] After drying, the polyamide composition E prepared in this embodiment was injection molded at 250°C using GB / T1040-2018 type 1A tensile specimens and GB / T1043-2018 simply supported beam impact specimens to test its mechanical properties; simultaneously, it was extruded to obtain... Observe the surface condition of the flexible tube (outer diameter 8mm, wall thickness 1mm), and test the surface resistance and precipitate content.

[0080] Comparative Example 1

[0081] This comparative example presents a polyamide composition, the preparation method of which includes the following steps: weighing 34.4 kg of medium-viscosity PA612 HB30, 30 kg of low-viscosity PA612 HB10, 3 kg of carbon nanotubes LG LUCAN BT1001M, 27 kg of polyether block amide MV2080 (manufactured by Arkema), 5 kg of toughening agent SEBS-g-MA, 0.3 kg of antioxidant 1098, and 0.3 kg of antioxidant 168 into a high-speed mixer and mixing them evenly, then granulating them using a twin-screw extruder to obtain polyamide composition F.

[0082] After drying, the polyamide composition F prepared using this comparative example was injection molded at 250°C using GB / T1040-2018 type 1A tensile specimens and GB / T1043-2018 simply supported beam impact specimens to test its mechanical properties; simultaneously, it was extruded to obtain... Observe the surface condition of the flexible tube (outer diameter 8mm, wall thickness 1mm), and test the surface resistance and precipitate content.

[0083] Comparative Example 2

[0084] This comparative example presents a polyamide composition, the preparation method of which includes the following steps: 64.4 kg of medium-viscosity PA612 and HB30, 30 kg of carbon nanotube masterbatch a prepared in Example 1, 5 kg of toughening agent SEBS-g-MA, 0.3 kg of antioxidant 1098, and 0.3 kg of antioxidant 168 are weighed and put into a high-speed mixer and mixed evenly. Then, the mixture is granulated using a twin-screw extruder to obtain polyamide composition G.

[0085] After drying, the polyamide composition G prepared using this comparative example was injection molded at 250°C using GB / T1040-2018 type 1A tensile specimens and GB / T1043-2018 simply supported beam impact specimens to test its mechanical properties; simultaneously, it was extruded to obtain... Observe the surface condition of the flexible tube (outer diameter 8mm, wall thickness 1mm), and test the surface resistance and precipitate content.

[0086] Comparative Example 3

[0087] This comparative example presents a polyamide composition, the preparation method of which includes the following steps: weighing 64.4 kg of low-viscosity PA612 and HB10, 30 kg of carbon nanotube masterbatch a prepared in Example 1, 5 kg of toughening agent SEBS-g-MA, 0.3 kg of antioxidant 1098, and 0.3 kg of antioxidant 168 into a high-speed mixer and mixing them evenly, then granulating them using a twin-screw extruder to obtain polyamide composition H.

[0088] After drying, the polyamide composition H prepared using this comparative example was injection molded at 250°C using GB / T1040-2018 type 1A tensile specimens and GB / T1043-2018 simply supported beam impact specimens to test its mechanical properties; simultaneously, it was extruded to obtain... Observe the surface condition of the flexible tube (outer diameter 8mm, wall thickness 1mm), and test the surface resistance and precipitate content.

[0089] Comparative Example 4

[0090] This comparative example presents a polyamide composition, the preparation method of which includes the following steps: weighing 34.4 kg of medium-viscosity PA612 HB30, 30 kg of low-viscosity PA612 HB10, 30 kg of carbon nanotube masterbatch a prepared in Example 1, 0.3 kg of antioxidant 1098, and 0.3 kg of antioxidant 168 into a high-speed mixer and mixing them evenly, then granulating them using a twin-screw extruder to obtain polyamide composition I.

[0091] After drying, the polyamide composition I prepared using this comparative example was injection molded at 250°C using GB / T1040-2018 type 1A tensile specimens and GB / T1043-2018 simply supported beam impact specimens to test its mechanical properties; simultaneously, it was extruded to obtain... Observe the surface condition of the flexible tube (outer diameter 8mm, wall thickness 1mm), and test the surface resistance and precipitate content.

[0092] Test case

[0093] This test example involves drying and injection molding a sample of the above-mentioned polyamide composition AI and performing mechanical property tests. Simultaneously, pipes with an outer diameter of 8 mm and a wall thickness of 1 mm are extruded, and the surface condition and surface resistance of the pipes are examined. The content of precipitates in the pipes is detected using the following method: A 2 m long pipe is filled with FAM Test Fluid DIN 51604B (FAM B, manufactured by Mecadi GmbH-Chemicals, Germany) solution and placed at 60°C for 96 h. The solution is then poured out and allowed to stand at 24°C for 24 h. 0.45 μm filter paper and an evaporating dish are heated at 40°C for 24 h, and then weighed. Insoluble and soluble impurities in the solution are collected using filter paper and an evaporating dish. The filter paper is heated at 40°C for 24 h and then weighed. The evaporating dish is allowed to evaporate naturally at room temperature and then heated at 40°C for 1 h before being weighed. The test results are shown in Table 1.

[0094] Table 1

[0095]

[0096] The results in Table 1 show that:

[0097] 1. Compared with the polyamide composition A in Example 1, the polyamide composition F in Comparative Example 1 had poor carbon nanotube dispersion due to the direct addition of carbon nanotubes during preparation, resulting in a rough tube surface and a surface resistivity of 5 × 10⁻⁶ during extrusion. 5 Ω is significantly higher than 2×10 in Example 1. 3 Ω; simultaneously, the elongation at break of the specimen decreased from 56% to 33%, and the notched impact strength of the specimen decreased from 62 KJ / m. 2 Dropped to 34 KJ / m 2 The material's toughness is significantly reduced.

[0098] 2. In Comparative Example 2, the polyamide composition G, due to the absence of low-viscosity polyamide resin, resulted in a high viscosity of the modified composition under the action of carbon nanotubes, making it impossible to extrude into pipes.

[0099] 3. In Comparative Example 3, the polyamide composition H, due to the absence of medium-viscosity polyamide resin, showed a decrease in elongation at break of the specimen from 56% in Example 1 to 31%, and a decrease in notched impact strength from 62 KJ / m. 2 Decreased to 29 KJ / m 2 The material's toughness is significantly reduced.

[0100] 4. In Comparative Example 4, the elongation at break of the polyamide composition I was reduced from 56% in Example 1 to 38% due to the absence of a toughening agent.

[0101] In Examples 1-5, by selecting low-exudation PA612 and PA1012 resins with a combination of medium and low viscosity, and adding carbon nanotube masterbatch, pipe materials with an exudate content of ≤0.5 g / m³ (insoluble impurities) were prepared. 2 Pipe precipitate content - soluble impurities ≤ 6g / m 2 It meets the requirements of the German Volkswagen VW TL52712 standard (a similar standard for low-emission fuel pipe efflorescence content is currently being developed in China); the surface resistivity of the pipe material is 10 Ω. 2 -10 4 Ω has excellent electrical conductivity; at the same time, the material has an elongation at break of ≥40% and good toughness; it is very suitable for producing conductive and low-emission products, such as fuel pipes.

[0102] It should be noted that when a component is said to be "installed on" another component, it can be directly on the other component or it may be in a component that is centered on it. When a component is said to be "set on" another component, it can be directly set on the other component or it may also be in a component that is centered on it. When a component is said to be "fixed to" another component, it can be directly fixed to the other component or it may also be in a component that is centered on it.

[0103] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "or / and" as used herein includes any and all combinations of one or more of the associated listed items.

[0104] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0105] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. An electrically conductive low-exudation polyamide composition characterized in that, It is prepared from the following components in parts by weight: 35 - 65 parts of polyamide resin, 20 - 50 parts of carbon nanotube masterbatch, 1 - 20 parts of toughening agent, 0.1 - 2 parts of antioxidant; wherein, the carbon nanotube masterbatch is a masterbatch prepared by coating carbon nanotubes with polyether block amide as the carrier; in the carbon nanotube masterbatch, the mass of the carbon nanotubes is 5% - 15% of the total mass of the carbon nanotube masterbatch; the polyamide resin includes: 30 - 60 parts of medium-viscosity long-chain polyamide resin, 5 - 30 parts of low-viscosity long-chain polyamide resin, the medium-viscosity long-chain polyamide resin is at least one of PA612 and PA1012, and its relative viscosity is 2.0 - 2.8; the low-viscosity long-chain polyamide resin is at least one of PA612 and PA1012, and its relative viscosity is 1.5 - 2.

0.

2. The conductive low outgassing polyamide composition of claim 1, wherein, The polyether block amide uses polyamide as the hard segment and polyether as the soft segment.

3. The conductive low outgassing polyamide composition of claim 1, wherein, The preparation process of the carbon nanotube masterbatch is: mixing polyamide and polyetheramine and then carrying out a polymerization reaction to obtain medium-low viscosity polyether amide; adding carbon nanotube particles to the medium-low viscosity polyether amide, stirring and dispersing evenly, and then carrying out underwater pelletizing and drying to obtain the carbon nanotube masterbatch.

4. The conductive low outgassing polyamide composition of claim 3, wherein, The polyamide is a carboxyl-terminated polyamide prepolymer, and the polyetheramine is polyethylene glycol etheramine; And / or, the process of the polymerization reaction is: adding polyamide and polyetheramine into a polymerization kettle and heating to 240°C, first reacting under normal pressure and nitrogen purging at this temperature for 3 hours, and then carrying out a vacuum reaction under a pressure of less than 500 Pa for 2 hours.

5. The conductive low outgassing polyamide composition of claim 1, wherein, The toughening agent is at least one of maleic anhydride grafted ethylene-octene, maleic anhydride grafted ethylene-butene copolymer elastomer, maleic anhydride grafted styrene-ethylene-butene-styrene block copolymer, and maleic anhydride grafted ethylene-propylene-diene monomer rubber; And / or, the antioxidant is at least one of antioxidant 1098, antioxidant 245, and antioxidant 168.

6. A process for the preparation of the conductive low-exudation polyamide composition according to any one of claims 1-5, characterized in that, It includes the following steps: mixing the polyamide resin, carbon nanotube masterbatch, toughening agent, and antioxidant evenly, and carrying out pelletizing through a twin-screw extruder to obtain the conductive low-precipitation polyamide composition.

7. Application of the conductive low-precipitation polyamide composition according to any one of claims 1 - 5 in a conductive fuel pipe.

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