CN118063882A - Conductive polypropylene product and its preparation method and application - Google Patents

Abstract

The invention relates to the field of polymer materials, and discloses a conductive polypropylene product, a preparation method and application thereof, wherein the conductive polypropylene product comprises a continuous phase and a disperse phase, the continuous phase is at least one oriented polypropylene, and the disperse phase is a conductive filler and optionally a dispersing auxiliary; the conductive fillers are distributed in parallel along the orientation direction of the polypropylene; based on the total weight of the conductive polypropylene product, the oriented polypropylene is used in an amount of 50-99 parts, the conductive filler is used in an amount of 1-50 parts, and the dispersing auxiliary is used in an amount of 0-30 parts; the conductivity of the conductive polypropylene product is more than or equal to 10 ^‑9 s/m. The polypropylene product prepared by the invention not only has good tensile strength and flexural modulus, but also has excellent conductivity, and can be used in fields with high requirements on mechanical properties and conductivity, such as electronics, medical treatment and the like.

Description

Conductive polypropylene product and its preparation method and application

Technical Field

The invention relates to the field of polymer materials, and in particular to a conductive polypropylene product and a preparation method and application thereof.

Background technique

Conductive products are functional products that have been widely used in many fields of the national economy. With the continuous advancement of science and technology, conductive composite materials have gradually expanded to high-tech fields such as aerospace and military industry. As these fields have increasingly higher requirements for the conductive properties of composite materials, researchers at home and abroad have tried to use different methods to prepare composite materials with higher conductive properties and stable mechanical properties to meet the requirements of use in high-conductivity fields.

CN107418045A discloses a modified polypropylene, which uses graphene to increase the conductivity of the composite material, uses glass fiber to improve the strength of the material, and uses a melt blending method to prepare a polypropylene material with conductivity and certain strength, with a maximum tensile strength of 110 MPa and a maximum impact strength of 18 kJ/m ² .

CN103304887A discloses a modified polypropylene. In this technology, a single-layer graphene is first pretreated and then melt-blended with polypropylene to obtain a polypropylene composite material with certain strength and conductivity.

In the current market, polypropylene products cannot have high strength, toughness and conductivity at the same time, which limits the application of polypropylene products in electronics, medical and other fields.

Summary of the invention

The purpose of the present invention is to overcome the problem that existing polypropylene products cannot have both high mechanical properties and electrical conductivity, and to provide a polypropylene product and a preparation method and application thereof. The conductive polypropylene product comprises oriented polypropylene and conductive fillers distributed in parallel along the orientation direction of the polypropylene. During the stretching process, the polypropylene molecular chains and lamellae are oriented, and the conductive fillers are oriented accordingly to form a conductive network, so that the polypropylene product has high mechanical properties and high electrical conductivity, and can be used in fields such as electronics and medical treatment that have high requirements for mechanical properties and electrical conductivity.

In order to achieve the above object, the first aspect of the present invention provides a conductive polypropylene product, characterized in that the conductive polypropylene product comprises a continuous phase and a dispersed phase, the continuous phase is at least one oriented polypropylene, the dispersed phase is a conductive filler and optionally a dispersing aid; the conductive filler is distributed in parallel along the orientation direction of the polypropylene;

Based on 100 parts by weight of the conductive polypropylene product, the amount of the oriented polypropylene is 50-99 parts, the amount of the conductive filler is 1-50 parts, and the amount of the dispersing aid is 0-30 parts;

The conductivity of the conductive polypropylene product is greater than or equal to 10 ^-9 S/m.

A second aspect of the present invention provides a method for preparing a conductive polypropylene product, characterized in that the method comprises the following steps:

(1) blending, extruding, granulating and molding polypropylene, a conductive filler and an optional dispersing aid to obtain a polypropylene blank;

(2) subjecting the above-mentioned polypropylene blank to die stretching to obtain a conductive polypropylene product;

Based on 100 parts by weight of the conductive polypropylene product, the amount of the oriented polypropylene is 50-99 parts, the amount of the conductive filler is 1-50 parts, and the amount of the dispersing aid is 0-30 parts.

The third aspect of the present invention provides a conductive polypropylene product produced by the above method.

A fourth aspect of the present invention provides a use of the conductive polypropylene product in the electronic and/or medical fields.

Through the above technical solution, the conductive polypropylene product provided by the present invention and its preparation method and application achieve the following beneficial effects:

In the present invention, the conductive polypropylene product contains at least one oriented polypropylene as a continuous phase and a conductive filler as a dispersed phase. The conductive filler is distributed in parallel along the orientation direction of the polypropylene to form a conductive network in the polypropylene product, and has good conductive properties.

In the present invention, the polypropylene molecular chains and lamellae in the polypropylene blank are oriented by adopting the die stretching method. During the orientation process, the conductive filler is further dispersed in the polypropylene as a dispersed phase, and a conductive network is generated as the molecular chains and lamellae are oriented, so that the prepared polypropylene product has not only good tensile strength and bending modulus, but also excellent conductivity, and can be used in fields such as electronics and medical treatment that have high requirements for mechanical properties and conductive properties.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a scanning electron microscope secondary electron photograph of a cross section of a conductive polypropylene product of Example 2;

FIG2 is a scanning electron microscope backscattered electron photograph of a cross section of the conductive polypropylene product of Example 3;

3 is a secondary electron photograph of a cross section of a conductive polypropylene product of Example 3 taken by a scanning electron microscope.

Detailed ways

The endpoints and any values of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoint values of each range, the endpoint values of each range and the individual point values, and the individual point values can be combined with each other to obtain one or more new numerical ranges, which should be regarded as specifically disclosed in this article.

Herein, the "die stretching" refers to stretching the polypropylene blank through a die of a fixed shape.

In this article, the "parallel distribution" refers to the parallel distribution of the conductive filler along the orientation direction of the polypropylene, and the degree of orientation is determined by the die stretching method. Therefore, the "parallel distribution" described in the present invention also includes the situation where the conductive filler has a certain angle with the orientation direction of the polypropylene. Specifically, the angle between the longest diameter direction of the conductive filler and the orientation direction of the polypropylene is less than or equal to 45°, preferably less than or equal to 30°, and more preferably less than or equal to 10°.

The first aspect of the present invention provides a conductive polypropylene product, characterized in that the conductive polypropylene product comprises a continuous phase and a dispersed phase, the continuous phase is at least one oriented polypropylene, the dispersed phase is a conductive filler and optionally a dispersing aid; the conductive filler is distributed in parallel along the orientation direction of the polypropylene;

Based on 100 parts by weight of the conductive polypropylene product, the amount of the oriented polypropylene is 50-99 parts, the amount of the conductive filler is 1-50 parts, and the amount of the dispersing aid is 0-30 parts;

The conductivity of the conductive polypropylene product is greater than or equal to 10 ^-9 s/m.

In the present invention, the conductive polypropylene product contains at least one oriented polypropylene as a continuous phase and a conductive filler as a dispersed phase, wherein the conductive filler is distributed in parallel along the orientation direction of the polypropylene, thereby forming a conductive path in the polypropylene, so that the polypropylene product can have excellent mechanical properties and greatly improve the conductive performance.

In the present invention, when the amounts of oriented polypropylene, conductive filler and dispersing aid meet the above ranges, the conductive filler as a dispersed phase and optionally the dispersing aid can be uniformly dispersed in the oriented polypropylene as a continuous phase, which is conducive to the conductive filler distributed in parallel along the orientation direction of the polypropylene to form a conductive path, and is not easy to form large agglomerates. Therefore, the polypropylene product not only has excellent mechanical properties, but also has higher conductivity.

Furthermore, based on 100 parts by weight of the conductive polypropylene product, the amount of the oriented polypropylene is 60-95 parts, the amount of the conductive filler is 5-40 parts, and the amount of the dispersing aid is 0.5-20 parts.

Furthermore, based on 100 parts by weight of the conductive polypropylene product, the amount of the oriented polypropylene is 60-90 parts, the amount of the conductive filler is 10-40 parts, and the amount of the dispersing aid is 1-10 parts.

Furthermore, the conductivity of the conductive polypropylene product is greater than or equal to 10 ^-8 s/m.

Furthermore, the conductivity of the conductive polypropylene product is preferably greater than or equal to 10 ^-7 s/m.

According to the present invention, the tensile strength of the conductive polypropylene product is greater than or equal to 100 MPa, preferably greater than or equal to 130 MPa.

According to the present invention, the flexural modulus of the conductive polypropylene product is greater than or equal to 3 GPa, preferably greater than or equal to 4 GPa.

According to the present invention, the conductivity of the conductive filler is 1-10 ⁹ S/m, preferably 5-10 ⁷ S/m.

In the present invention, the electrical conductivity of the conductive filler refers to the electrical conductivity of the filler measured before the filler is stretched through a die.

According to the present invention, the conductive filler is selected from at least one of a flake conductive filler, a fibrous conductive filler and a rectangular block conductive filler, and optionally a spherical conductive filler.

In the present invention, the morphology of the conductive filler refers to the morphology of the conductive filler in the conductive polypropylene product after being stretched.

In the present invention, when the conductive filler in the polypropylene product has the above-mentioned morphology, the conductive filler can be distributed in the polypropylene in parallel along the orientation direction of the polypropylene, and the prepared polypropylene product not only has good strength, but also has high conductivity.

According to the present invention, the aspect ratios of the flake-shaped conductive filler, the fibrous conductive filler and the rectangular block-shaped conductive filler are independently 2-100,000:1.

In the present invention, the aspect ratio of the conductive filler refers to the ratio of the longest diameter to the shortest diameter of the filler in the SEM photo. Specifically, for a sheet filler, the longest diameter is the sheet diameter of the sheet filler, and the shortest diameter is the thickness of the sheet filler; for a fibrous filler, the longest diameter is the length of the fibrous filler, and the shortest diameter is the diameter of the fibrous filler; for a rectangular block filler, the longest diameter is the longest side length of the rectangular block filler, and the shortest diameter is the shortest side length of the rectangular block filler.

In the present invention, when the size of the conductive filler satisfies the above-mentioned aspect ratio range, the conductive filler can be oriented with the molecular chains and crystals in the polypropylene, thereby improving the mechanical properties of the polypropylene product; further, the conductive filler is distributed in the polypropylene in parallel along the stretching direction, which is more conducive to forming a conductive network, thereby improving the conductivity of the polypropylene product with the stretching orientation; under the combined effect of these two aspects, the polypropylene product has the effects of high strength and high conductivity.

Furthermore, the aspect ratios of the flake-shaped conductive filler, the fibrous conductive filler and the rectangular block-shaped conductive filler are independently 3-50,000:1.

Furthermore, the aspect ratios of the flake-shaped conductive filler, the fibrous conductive filler and the rectangular block-shaped conductive filler are independently 3-40,000:1.

In the present invention, there is no particular limitation on the specific type of fibrous conductive filler, as long as the aspect ratio of the fibrous conductive filler meets the requirements of the present invention. For example, the fibrous conductive filler may include carbon nanotubes, carbon fibers, single-component metal fibers, and metal alloy fibers.

In the present invention, there is no particular limitation on the specific type of the flaky conductive filler, as long as the aspect ratio of the flaky conductive filler meets the requirements of the present invention. For example, the flaky conductive filler may be flaky graphite, graphene, or the like.

In the present invention, there is no particular limitation on the specific type of the rectangular block conductive filler, as long as the aspect ratio of the rectangular block conductive filler meets the requirements of the present invention. For example, the rectangular block conductive filler may be block graphite.

In the present invention, there is no particular limitation on the specific type of the spherical conductive filler, which may be a conventional spherical conductive filler in the art, such as conductive carbon black, single-component metal particles, and metal alloy particles.

According to the present invention, the conductive filler is a flake conductive filler, and the average diameter of the conductive filler is 10 nm-500 μm.

In the present invention, the average diameter of the flake-like conductive filler refers to the average diameter of the flake-like filler in the SEM photograph.

In the present invention, when the average diameter of the above-mentioned flaky conductive filler is too low, the flaky conductive fillers dispersed in the oriented polypropylene matrix are not easy to overlap with each other and are not easy to form a conductive network; when the average diameter of the flaky fillers is too high, the difficulty of uniformly dispersing the conductive fillers in the polypropylene increases, defects are easily formed during the orientation process, and the subsequent processing and the performance of the polypropylene products are affected.

Furthermore, the conductive filler is a flake conductive filler, and the average diameter of the conductive filler is 100 nm-400 μm.

Furthermore, the conductive filler is a flake conductive filler, and the average diameter of the conductive filler is 1 μm-200 μm.

According to the present invention, the conductive filler is a fibrous filler, and the cross-sectional diameter of the conductive filler is 1 nm-50 μm.

In the present invention, the cross-sectional diameter of the fibrous conductive filler refers to the average cross-sectional diameter of the fibrous conductive filler in the SEM photograph.

Furthermore, the conductive filler is a fibrous filler, and the cross-sectional diameter of the conductive filler is 5 nm-20 μm.

Furthermore, the conductive filler is a fibrous filler, and the cross-sectional diameter of the conductive filler is 7nm-15μm.

In a specific embodiment of the present invention, the aspect ratio of the flake filler is 10-50,000:1, preferably 15-40,000:1; the average diameter of the flake filler is 1-500 μm, preferably 5-300 μm.

In a specific embodiment of the present invention, the aspect ratio of the fibrous filler is 2-5,000:1, preferably 2-4,000:1; the cross-sectional diameter of the fibrous filler is 2nm-20μm, preferably 5nm-15μm.

In a specific embodiment of the present invention, the conductive filler comprises flaky conductive filler and/or fibrous conductive filler and optionally rectangular block conductive filler, wherein the amount of the flaky conductive filler and/or fibrous conductive filler is 0.1-10 parts relative to 100 parts by weight of the conductive filler.

In a specific embodiment of the present invention, the conductive filler is selected from fibrous conductive filler and/or flake conductive filler, wherein the mass ratio of the fibrous conductive filler to the flake conductive filler is 1:0.1-5.

In a specific embodiment of the present invention, the conductive filler includes a fibrous conductive filler and a spherical conductive filler, wherein the mass ratio of the fibrous conductive filler to the spherical conductive filler is 10-20:1.

According to the present invention, the polypropylene is selected from homopolypropylene and/or copolymer polypropylene.

Preferably, the melt index of the polypropylene at 230° C. and a load of 2.16 kg is 0.1-200 g/10 min, preferably 0.1-150 g/10 min.

In the present invention, the copolymerized polypropylene is a copolymer of propylene and at least one comonomer selected from ethylene, butene and hexene. There is no particular limitation on the content of the structural unit derived from the comonomer in the copolymerized polypropylene, which may be a conventional content in the art.

According to the present invention, the dispersing aid is selected from surfactants and/or polymer compatibilizers.

In the present invention, the surfactant includes but is not limited to isocyanate, silane coupling agent, polyvinyl pyrrolidone, sodium dodecylbenzene sulfonate, sodium lignin sulfonate, polyvinyl alcohol, polyethylene oxide, polyacrylic acid, polymethacrylic acid and polyacrylamide.

In the present invention, the polymer compatibilizer includes but is not limited to maleic anhydride copolymer and its derivatives, butyl methacrylate copolymer and its derivatives, acrylic acid copolymer and its derivatives, glycidyl methacrylate copolymer and its derivatives. The derivative refers to a substance obtained by modifying the acid, anhydride, ester and other groups in the copolymer by chemical methods.

According to the present invention, the conductive polypropylene product further comprises a release agent, and the amount of the release agent is 0-20 parts based on 100 parts by weight of the conductive polypropylene product.

In the present invention, the isolating agent can separate the conductive fillers in the polypropylene to prevent the fillers from agglomerating; especially for metal alloy conductive fillers, especially tin-bismuth alloy conductive fillers, the isolating agent can prevent the low-melting-point metal from overflowing during melting and stretching, thereby obtaining a polypropylene product with stable conductive properties.

Furthermore, the conductive polypropylene product further comprises a release agent, and the amount of the release agent is 1-10 parts based on 100 parts by weight of the conductive polypropylene product.

Furthermore, the release agent is selected from at least one of glass microspheres, nano barium sulfate, montmorillonite, nano silicon dioxide and nano powder rubber release agents with a cross-linked structure.

Furthermore, the shape of the separator is selected from fiber and/or sheet.

In a specific embodiment of the present invention, when the conductive filler comprises a metal alloy, preferably a tin-bismuth alloy, an isolating agent is preferably added to the polypropylene product to prevent the metal alloy from overflowing during the die stretching process.

In the present invention, in the polypropylene product, the total amount of polypropylene, conductive filler, dispersing aid and release agent is 100 parts.

In the present invention, the polypropylene product contains an antioxidant, and the antioxidant is dispersed in the oriented polypropylene as a dispersed phase. Preferably, based on 100 parts of the conductive polypropylene product, the amount of the antioxidant is 0-3 parts, preferably 0.01-2 parts, and more preferably 0.01-1 part.

In the present invention, the antioxidant may be a conventional antioxidant in the art, and the antioxidant is selected from at least one of hindered amines, hindered phenols, antioxidant 1010 and antioxidant 168.

In a specific embodiment of the present invention, the antioxidants are antioxidant 1010 and antioxidant 168; wherein the mass ratio of the antioxidant 1010 to the antioxidant 168 is 1:0.5-2.

According to the present invention, the cross-sectional shape of the conductive polypropylene product is at least one of circular, nearly circular, triangular, rectangular, rhombus, trapezoidal and polygonal.

According to the present invention, the cross-section of the conductive polypropylene product is rectangular, and the aspect ratio of the cross-section of the conductive polypropylene product is less than or equal to 500.

According to the present invention, the cross-section of the conductive polypropylene product is circular or nearly circular, and the diameter of the cross-section of the conductive polypropylene product is greater than or equal to 1 mm.

A second aspect of the present invention provides a method for preparing a conductive polypropylene product, characterized in that the method comprises the following steps:

(1) blending, extruding, granulating and molding polypropylene, a conductive filler and an optional dispersing aid to obtain a polypropylene blank;

(2) subjecting the above-mentioned polypropylene blank to die stretching to obtain a conductive polypropylene product;

Based on 100 parts by weight of the conductive polypropylene product, the amount of the oriented polypropylene is 50-99 parts, the amount of the conductive filler is 1-50 parts, and the amount of the dispersing aid is 0-30 parts.

The method of the present invention orients the polypropylene molecular chains and lamellae by performing die stretching, and the conductive filler as a dispersed phase can be oriented along with the changes of the polypropylene molecular chains and lamellae, so that the polypropylene product prepared thereby has high mechanical properties and high conductivity; further, during the die stretching process, the conductive filler is oriented and distributed in parallel along the orientation direction of the polypropylene, so that the conductive fillers overlap each other to form a conductive path. Therefore, when the addition amount of the conductive filler is low, the product prepared by the present invention also has high conductivity and high strength.

Preferably, step (1) further comprises: blending, extruding, granulating and molding polypropylene, conductive filler, optionally a dispersing aid, optionally an antioxidant and optionally a release agent to obtain a polypropylene blank.

In the preparation method of the conductive polypropylene product in the second aspect of the present invention, the composition and amount of polypropylene, conductive filler, dispersing aid, antioxidant and release agent are exactly the same as the composition and amount of polypropylene, conductive filler, dispersing aid, antioxidant and release agent in the conductive polypropylene product described in the first aspect of the present invention. In order to avoid repetition, the present invention will not be described in detail in the second aspect, and those skilled in the art should not understand it as a limitation of the present invention.

According to the present invention, the actual stretching ratio of the die stretching is 1.1-50, the stretching temperature of the die stretching is 90-155° C., and the stretching speed of the die stretching is 1-1000 mm/min.

In the present invention, by controlling the above-mentioned die stretching conditions, the conductivity of the polypropylene product in the stretching direction can be improved, which can not only ensure the stability of the product shape and performance, but also improve the production efficiency of the polypropylene product. Specifically, the die stretching ratio has a significant effect on the orientation degree of the molecular chain, crystal and conductive filler in the polypropylene product, thereby affecting the conductivity of the polypropylene product along the stretching direction; when the stretching temperature and stretching speed meet the above conditions, not only can the actual stretching ratio be better controlled, but also the production efficiency is higher.

In the present invention, the actual stretch ratio refers to the ratio of the cross-sectional area of the polypropylene blank to the cross-sectional area of the polypropylene product.

Furthermore, the actual stretching ratio of the die stretching is 2-40 times, the stretching temperature of the die stretching is 95-150° C., and the stretching speed of the die stretching is 1-500 mm/min.

Furthermore, the actual stretching ratio of the die stretching is 4-20 times, the stretching temperature of the die stretching is 100-150° C., and the stretching speed of the die stretching is 5-500 mm/min.

In the present invention, the die for die stretching is a heatable metal cavity with a certain inlet cross-sectional area and an outlet cross-sectional area.

In the present invention, the die stretching equipment is composed of a traction device, a stretching die head, a heating cavity and a temperature control device.

In the present invention, the shape of the die for die stretching is selected from at least one of a circle, a triangle, a rectangle, a rhombus, a trapezoid and a polygon.

In the present invention, the preparation method of the polypropylene blank is a common plastic processing method, such as but not limited to injection molding, compression molding, extrusion molding and rotational molding.

The third aspect of the present invention provides a conductive polypropylene product produced by the above method.

A fourth aspect of the present invention provides an application of the conductive polypropylene product in the electronic and/or medical fields.

The experimental data in the embodiments are tested and calculated using the following method:

(1) The tensile strength shall be tested in accordance with GB/T1040-2006 “Determination of tensile properties of plastics”;

(2) The flexural modulus is tested in accordance with GB/T9341-2008 “Determination of flexural properties of plastics”;

(3) Conductivity of polypropylene products: Conductivity = 1/resistivity. When the conductivity of the product is less than 10 ^-4 S/m, follow GB/T15662-1995 "Test method for volume resistivity of conductive and antistatic plastics"; when the conductivity is greater than 10 ^-4 S/m, follow GB/T1410-2006 "Test method for volume resistivity and surface resistivity of solid insulating materials".

(4) Aspect ratio of the conductive filler: The longest diameter and the shortest diameter are obtained by scanning electron microscopy analysis;

(5) The morphology of polypropylene products was obtained by scanning electron microscopy observation and analysis;

The experimental data in the examples were tested using the following instruments:

(1) Tensile strength and flexural modulus: Instron universal testing machine, model 3366;

(2) Conductivity: High resistance meter, model CXT268, produced by Changzhou Xinyang Electronic Technology Co., Ltd.

(3) Electron microscope image: COXEM EM30 Plus scanning electron microscope, South Korea.

In the following embodiments,

The homopolymer polypropylene resin is a commercial product with the brand name PPH-T03 produced by Maoming Petrochemical; its melt index is 3g/10min, and the test conditions are 230°C and a load of 2.16kg;

The copolymerized polypropylene is a commercial product of the brand PPB-M30-V produced by Yangzi Petrochemical Company. Its melt index is 30 g/10 min. The test conditions are 230° C. and a load of 2.16 kg.

The random copolymer polypropylene is a commercial product of grade M60ET produced by Zhenhai Refining and Chemical Industry; its melt index is 60g/10min, and the test conditions are 230°C and a load of 2.16kg;

The impact copolymer polypropylene is a commercial product of grade K8303 produced by Yanshan Petrochemical; its melt index is 2g/10min, and the test conditions are 230°C and a load of 2.16kg;

Release agent A: Nano-silicon dioxide a, a commercial product of Shanghai Yaoyi Alloy Materials Co., Ltd., with an average particle size of 20 nm

Release agent B: ultrafine fully vulcanized carboxylated styrene butadiene nanopowder rubber, a commercial product of Beijing Institute of Chemical Industry, with an average particle size of 90 nm;

Polymer compatibilizer A: maleic anhydride/styrene random copolymer, commercially available from Crévaliere, France, with the brand name 2000-P;

Polymer compatibilizer B: Glycidyl methacrylate is a commercial product of Nanjing Xiangqian Chemical Co., Ltd.;

Surfactant: Silane coupling agent is a commercial product of Nanjing Xiangqian Chemical Co., Ltd., brand KH570;

The types, conductivity and sources of the conductive fillers in the embodiments and comparative examples are shown in Table 1.

Table 1

Conductive filler Conductivity (S/m) production company 1 Multi-walled carbon nanotubes 10 ⁴ Jiangsu Tiannai Technology Co., Ltd. 2 Tin-bismuth alloy powder 10 ⁵ Shanghai Alloy Welding Material Factory 3 Copper powder 10 ⁷ Nangong Ruiteng Alloy Materials Co., Ltd. 4 Flake graphite 10 Qingdao Dongkai Graphite Co., Ltd. 5 Few-layer graphene (1-3 layers) 10 ⁵ Xiamen Kaina Graphene Co., Ltd. 6 carbon fiber 10 Shenzhen Zhongsen Pilot Technology Co., Ltd. 7 Gold Nanoparticles 10 ⁷ Beijing High Entropy Alloy New Material Technology Co., Ltd.

Example 1

90 parts of homopolymer polypropylene resin PPH-T03, 9 parts of multi-walled carbon nanotubes, and 1 part of surfactant were selected. 0.15 parts of antioxidant 1010 and 0.15 parts of antioxidant 168 were added, and the mixture was extruded and granulated using a twin-screw extruder. Specifically, the blank was prepared by injection molding, and the cross-section of the blank was circular. Specifically, the conditions for the blending and extrusion were as follows: the temperatures of each section of the twin-screw extruder were 190°C, 200°C, 210°C, 210°C, 210°C, and the screw speed was 300rpm. In the injection molding, the screw temperature was 220°C, the injection speed was 10mm/s, the injection pressure was 600bar, the holding time was 60s, and the holding pressure was 600bar.

A circular die was selected, the blank was heated to 130°C, and the traction device pulled the blank through the stretching die head at a speed of 5 mm/min. The stretching temperature was 130°C, and then the blank was cooled and shaped, and the polypropylene product A1 was obtained by cutting. Its actual stretching ratio was 20.6, and the final cross-section was a circle with a diameter of 0.728 cm.

Example 2

80 parts of copolymerized polypropylene PPB-M30-V, 1 part of nano-gold particles, 17 parts of carbon fibers, 2 parts of polymer compatibilizer A, 0.15 parts of antioxidant 1010 and 0.15 parts of antioxidant 168 were added, and the mixture was blended and extruded into granules using a twin-screw extruder. A blank was prepared by injection molding. Specifically, the conditions for blending, extruding and granulating and the conditions for preparing the blank were the same as those in Example 1.

A circular die was selected, the blank was heated to 120°C, and the traction device pulled the blank through the stretching die head at a speed of 20 mm/min. The stretching temperature was 120°C, and then the blank was cooled and shaped, and the polypropylene product A2 was obtained by cutting. Its actual stretching ratio was 10.7, and the final cross-section was a circle with a diameter of 1.40 cm.

Example 3

60 parts of random copolymer polypropylene M60ET, 12.5 parts of tin-bismuth alloy powder, 20 parts of flake graphite, 2.5 parts of release agent B, 5 parts of silane coupling agent KH570, 0.15 parts of antioxidant 1010 and 0.15 parts of antioxidant 168 were added, and the mixture was blended and extruded into granules using a twin-screw extruder. The blank was prepared by injection molding. Specifically, the conditions for blending, extruding and granulating and the blank preparation conditions were the same as those in Example 1.

A circular die was selected, the blank was heated to 140°C, and the traction device pulled the blank through the stretching die head at a speed of 50 mm/min. The stretching temperature was 140°C, and then the blank was cooled and shaped, and the polypropylene product A3 was obtained by cutting. Its actual stretching ratio was 4.6, and the final cross-section was a circle with a diameter of 3.26 cm.

Example 4

70 parts of impact copolymer polypropylene K8303, 25 parts of few-layer graphene, 5 parts of polymer compatibilizer B, antioxidant 1010 and 0.15 parts of antioxidant 168 were selected and blended and extruded into granules using a twin-screw extruder. A blank was prepared by injection molding. Specifically, the conditions for blending, extruding and granulating and the blank preparation conditions were the same as those in Example 1.

A circular die was selected, the blank was heated to 145°C, and the traction device pulled the blank through the stretching die head at a speed of 30 mm/min. The stretching temperature was 145°C, and then the blank was cooled and shaped, and the polypropylene product A4 was cut to obtain the actual stretching ratio of 8.7, and the final cross-section was a circle with a diameter of 1.72 cm.

Example 5

70 parts of homopolymer polypropylene resin PPH-T03, 25 parts of flake graphite, and 5 parts of polymer compatibilizer A were selected. 0.15 parts of antioxidant 1010 and 0.15 parts of antioxidant 168 were added, and the mixture was blended and extruded into granules using a twin-screw extruder. A blank was prepared by injection molding. Specifically, the blending, extrusion and granulation conditions and the blank preparation conditions were the same as those in Example 1.

A circular die was selected, the blank was heated to 150°C, and the traction device pulled the blank through the stretching die head at a speed of 500 mm/min. The stretching temperature was 150°C, and then it was cooled and shaped, and the polypropylene product A5 was cut to obtain the actual stretching ratio of 10.7, and the final cross-section was a circle with a diameter of 1.40 cm.

Example 6

70 parts of homopolymer polypropylene resin PPH-T03, 20 parts of carbon fiber, 5 parts of few-layer graphene, and 5 parts of polymer compatibilizer A were selected. 0.15 parts of antioxidant 1010 and 0.15 parts of antioxidant 168 were added, and the mixture was blended and extruded into granules using a twin-screw extruder. A blank was prepared by injection molding. Specifically, the blending, extrusion and granulation conditions and the blank preparation conditions were the same as those in Example 1.

A circular die was selected, the blank was heated to 130°C, and the traction device pulled the blank through the stretching die at a speed of 100 mm/min. The stretching temperature was 130°C, and then the blank was cooled and shaped, and the polypropylene product A6 was obtained by cutting. Its actual stretching ratio was 10.7, and the final cross-section was a circle with a diameter of 1.40 cm.

Example 7

80 parts of copolymerized polypropylene PPB-M30-V, 1 part of nano-gold particles, 17 parts of multi-walled carbon nanotubes, 2 parts of polymer compatibilizer A, 0.15 parts of antioxidant 1010 and 0.15 parts of antioxidant 168 were added, and the mixture was blended and extruded into granules using a twin-screw extruder. A blank was prepared by injection molding. Specifically, the blending, extrusion and granulation conditions and the blank preparation conditions were the same as those in Example 1.

A circular die was selected, the blank was heated to 120°C, and the traction device pulled the blank through the stretching die at a speed of 20 mm/min. The stretching temperature was 120°C, and then the blank was cooled and shaped, and the polypropylene product A7 was obtained by cutting. Its actual stretching ratio was 10.7, and the final cross-section was a circle with a diameter of 1.40 cm.

Comparative Example 1

100 parts of homopolymer polypropylene resin PPH-T03, 0.15 parts of antioxidant 1010, and 0.15 parts of antioxidant 168 were selected and extruded and granulated using a twin-screw extruder. The above polypropylene raw materials were injected into mechanical test specimens D1 by injection molding. Among them, the conditions of blending extrusion granulation and the injection molding preparation conditions of the test samples were the same as those in Example 1.

Comparative Example 2

90 parts of homopolymer polypropylene resin PPH-T03, 9 parts of multi-walled carbon nanotubes, 1 part of release agent A, 0.15 parts of antioxidant 1010, and 0.15 parts of antioxidant 168 were selected, blended by a twin-screw extruder and then injection molded to prepare sample D2. The conditions of blending extrusion granulation and injection molding preparation conditions of the test sample were the same as those in Example 1.

Comparative Example 3

100 parts of homopolymer polypropylene resin PPH-T03, 0.15 parts of antioxidant 1010, and 0.15 parts of antioxidant 168 were selected and extruded and granulated by a twin-screw extruder. A blank was prepared by injection molding, and the cross section of the blank was circular. Specifically, the conditions for blending, extrusion and granulation and the conditions for preparing the blank were the same as those in Example 1.

A circular die was selected, the blank was heated to 130°C, and the traction device pulled the blank through the stretching die at a speed of 5 mm/min. After that, it was cooled and shaped, and cut to obtain the polypropylene product D3, whose actual stretching ratio was 20.6, and the final cross-section was a circle with a diameter of 0.728 cm.

Comparative Example 4

30 parts of homopolymer polypropylene resin PPH-T03, 10 parts of multi-walled carbon nanotubes, 60 parts of flake graphite, 0.15 parts of antioxidant 1010, and 0.15 parts of antioxidant 168 were selected, and the raw billet was prepared by blending with a twin-screw extruder and then injection molding. Specifically, the conditions for blending, extrusion granulation and raw billet preparation were the same as those in Example 1.

A circular die was selected, the blank was heated to 130°C, and the traction device attempted to stretch it at a speed of 10 mm/min. The stretching temperature was 130°C, but it broke during the stretching process. The overfilling caused the blank to be unable to be stretched.

Comparative Example 5

90 parts of homopolymer polypropylene resin PPH-T03, 9 parts of multi-walled carbon nanotubes, 1 part of spacer A, 0.15 parts of antioxidant 1010, and 0.15 parts of antioxidant 168 were selected, and extruded and granulated using a twin-screw extruder. A blank was prepared by injection molding. Specifically, the conditions for blending, extruding and granulating and the conditions for preparing the blank were the same as those in Example 1.

The blank was heated to 130°C, and stretched at a speed of 10 mm/min in a 130°C oven by a traction device without passing through a die. Free stretching occurred, and necking and breakage occurred, and no stretched oriented product was obtained.

Comparative Example 6

90 parts of homopolymer polypropylene resin PPH-T03, 9 parts of copper powder, 1 part of polymer compatibilizer A, 0.15 parts of antioxidant 1010, and 0.15 parts of antioxidant 168 were selected, and extruded and granulated using a twin-screw extruder. A blank was prepared by injection molding. Specifically, the conditions for blending, extruding and granulating and the conditions for preparing the blank were the same as those in Example 1.

The blank was heated to 130°C, and the traction device pulled the blank through the stretching die at a speed of 5 mm/min. The stretching temperature was 130°C, and then cooled and shaped. The polypropylene product D6 was cut to obtain a practical stretching ratio of 20.6, and the final cross-section was a circle with a diameter of 0.728 cm.

The morphology of the polypropylene products obtained in the examples and comparative examples was tested, and the morphology and size of the conductive fillers in the polypropylene products were observed. The results are shown in Table 2.

Table 2

The tensile strength, flexural modulus and electrical conductivity of the polypropylene products obtained in the embodiments and preparation examples were tested, and the results are shown in Table 3.

table 3

Figure 1 is a scanning electron microscope secondary electron photograph of the cross section of the conductive polypropylene product of Example 2. It can be seen that the carbon fibers are clearly oriented along the stretching direction. Specifically, the average angle between the length direction of the carbon fibers and the orientation direction of the polypropylene is less than or equal to 5°.

FIG2 is a scanning electron microscope backscattered electron photograph of the cross section of the conductive polypropylene product of Example 3, and FIG3 is a scanning electron microscope secondary electron photograph of the cross section of the conductive polypropylene product of Example 3. Compared with FIG3 , the white fibers in FIG2 are fibers formed of tin-bismuth alloy, and it can be seen that the tin-bismuth alloy fibers are obviously oriented along the stretching direction. Specifically, the average angle between the length direction of the tin-bismuth alloy fibers and the orientation direction of the polypropylene is less than or equal to 30°.

As shown in Table 3 above, the conductivity of the polypropylene product is significantly improved with the change of the stretching conditions and the amount of conductive filler added. It can be seen from Examples 1-7 that the conductive filler with a certain shape and aspect ratio will be oriented in the polypropylene matrix with the die stretching of the polypropylene. After the two are oriented at the same time, a polypropylene product with high tensile strength and high bending modulus is obtained, and at the same time, it has excellent conductive properties, and its conductivity is greater than ^10-9 S/m; it can be seen from Comparative Examples 1-5 that when the conductive filler content is too high and free stretching or no die stretching is performed, the prepared product does not have the effect of the present invention. The filler with a certain shape during the die stretching process can further improve the mechanical properties and conductivity; it can be seen from Comparative Example 6 that when a spherical conductive filler is used alone, the spherical conductive filler cannot be oriented with the polypropylene molecular chain during the die stretching process, and it is difficult to form a conductive network. Compared with Example 1, the polypropylene product prepared in Comparative Example 6 has lower tensile strength, bending modulus and conductivity, and cannot be used in fields with high requirements for conductive properties.

The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims (11)

1. A conductive polypropylene product, characterized in that the conductive polypropylene product comprises a continuous phase and a dispersed phase, the continuous phase is at least one oriented polypropylene, the dispersed phase is a conductive filler and optionally a dispersing aid; the conductive filler is distributed in parallel along the orientation direction of the polypropylene; Based on 100 parts by weight of the conductive polypropylene product, the amount of the oriented polypropylene is 50-99 parts, the amount of the conductive filler is 1-50 parts, and the amount of the dispersing aid is 0-30 parts; The conductivity of the conductive polypropylene product is greater than or equal to 10 ^-9 S/m. 2. The conductive polypropylene product according to claim 1, wherein, based on 100 parts by weight of the conductive polypropylene product, the amount of the oriented polypropylene is 60-95 parts, preferably 60-90 parts, the amount of the conductive filler is 5-40 parts, preferably 10-40 parts, and the amount of the dispersing aid is 0.5-20 parts, preferably 1-10 parts; Preferably, the electrical conductivity of the conductive polypropylene product is greater than or equal to 10 ^-8 S/m, preferably greater than or equal to 10 ^-7 S/m. 3. The conductive polypropylene product according to claim 1 or 2, wherein the tensile strength of the conductive polypropylene product is greater than or equal to 100 MPa, preferably greater than or equal to 130 MPa; Preferably, the flexural modulus of the conductive polypropylene product is greater than or equal to 3 GPa, preferably greater than or equal to 4 GPa. 4. The conductive polypropylene product according to any one of claims 1 to 3, wherein the conductivity of the conductive filler is 1-10 ⁹ S/m, preferably 5-10 ⁷ S/m; Preferably, the conductive filler is selected from at least one of a flake conductive filler, a fibrous conductive filler and a rectangular block conductive filler and an optional spherical conductive filler; Preferably, the aspect ratio of the flake conductive filler, the fibrous conductive filler and the cuboid block conductive filler is independently 2-100,000:1, preferably 3-50,000:1, more preferably 3-40,000:1; Preferably, the conductive filler is a flake conductive filler, and the average diameter of the conductive filler is 10 nm-500 μm, preferably 100 nm-400 μm, and more preferably 1 μm-200 μm; Preferably, the conductive filler is a fibrous filler, and the cross-sectional diameter of the conductive filler is 1 nm-50 μm, preferably 5 nm-20 μm, and more preferably 7 nm-15 μm. 5. The conductive polypropylene product according to any one of claims 1 to 4, wherein the polypropylene is selected from homopolypropylene and/or copolymer polypropylene; Preferably, the melt index of the polypropylene at 230° C. and a load of 2.16 kg is 0.1-200 g/10 min, preferably 0.1-150 g/10 min. 6. The conductive polypropylene product according to any one of claims 1 to 5, wherein the dispersing aid is selected from a surfactant and/or a polymer compatibilizer; Preferably, the conductive polypropylene product further comprises a release agent, and the amount of the release agent is 0-20 parts, preferably 1-10 parts, based on 100 parts by weight of the conductive polypropylene product; Preferably, the release agent is selected from at least one of glass microspheres, nano barium sulfate, montmorillonite, nano silicon dioxide and nano powder rubber particles with a cross-linked structure; Preferably, the shape of the release agent is selected from fiber and/or sheet. 7. The conductive polypropylene product according to any one of claims 1 to 6, wherein the cross-sectional shape of the conductive polypropylene product is at least one of circular, nearly circular, triangular, rectangular, rhombus, trapezoidal and polygonal; Preferably, the cross-section of the conductive polypropylene product is rectangular, and the aspect ratio of the cross-section of the conductive polypropylene product is less than or equal to 500; Preferably, the cross-section of the conductive polypropylene product is circular or nearly circular, and the diameter of the cross-section of the conductive polypropylene product is greater than or equal to 1 mm. 8. A method for preparing a conductive polypropylene product, characterized in that the method comprises the following steps: (1) blending, extruding, granulating and molding polypropylene, a conductive filler and an optional dispersing aid to obtain a polypropylene blank; (2) subjecting the above-mentioned polypropylene blank to die stretching to obtain a conductive polypropylene product; Based on 100 parts by weight of the conductive polypropylene product, the amount of the oriented polypropylene is 50-99 parts, the amount of the conductive filler is 1-50 parts, and the amount of the dispersing aid is 0-30 parts. 9. The method according to claim 8, wherein the actual stretching ratio of the die stretching is 1.1-50 times, the stretching temperature of the die stretching is 90-155°C, and the stretching speed of the die stretching is 1-1000 mm/min; Preferably, the actual stretching ratio of the die stretching is 2-40 times, the stretching temperature of the die stretching is 95-150° C., and the stretching speed of the die stretching is 1-500 mm/min; More preferably, the actual stretching ratio of the die stretching is 4-20 times, the stretching temperature of the die stretching is 100-150° C., and the stretching speed of the die stretching is 5-500 mm/min. 10. A conductive polypropylene product obtained by the method according to claim 8 or 9. 11. Use of the conductive polypropylene product according to any one of claims 1 to 7 and 10 in the electronic and/or medical fields.