WO2020211311A1 - 具有三维导电网络的橡胶/低熔点合金/纳米碳复合材料及其制备方法 - Google Patents

具有三维导电网络的橡胶/低熔点合金/纳米碳复合材料及其制备方法 Download PDF

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WO2020211311A1
WO2020211311A1 PCT/CN2019/111526 CN2019111526W WO2020211311A1 WO 2020211311 A1 WO2020211311 A1 WO 2020211311A1 CN 2019111526 W CN2019111526 W CN 2019111526W WO 2020211311 A1 WO2020211311 A1 WO 2020211311A1
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rubber
melting point
low melting
nano
point alloy
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郭建华
熊俊彬
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华南理工大学
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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K3/00—Use of inorganic substances as compounding ingredients
    • C08K3/02—Elements
    • C08K3/04—Carbon
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K3/00—Use of inorganic substances as compounding ingredients
    • C08K3/02—Elements
    • C08K3/04—Carbon
    • C08K3/041—Carbon nanotubes
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K3/00—Use of inorganic substances as compounding ingredients
    • C08K3/02—Elements
    • C08K3/04—Carbon
    • C08K3/042—Graphene or derivatives, e.g. graphene oxides
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K3/00—Use of inorganic substances as compounding ingredients
    • C08K3/02—Elements
    • C08K3/04—Carbon
    • C08K3/045—Fullerenes
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K3/00—Use of inorganic substances as compounding ingredients
    • C08K3/02—Elements
    • C08K3/08—Metals
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K3/00—Use of inorganic substances as compounding ingredients
    • C08K3/34—Silicon-containing compounds
    • C08K3/36—Silica
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K5/00—Use of organic ingredients
    • C08K5/04—Oxygen-containing compounds
    • C08K5/14—Peroxides
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K3/00—Use of inorganic substances as compounding ingredients
    • C08K3/02—Elements
    • C08K3/08—Metals
    • C08K2003/0837—Bismuth
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K2201/00—Specific properties of additives
    • C08K2201/001—Conductive additives
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K2201/00—Specific properties of additives
    • C08K2201/011—Nanostructured additives

Definitions

  • the invention relates to a rubber composite material, and more particularly to a rubber/low melting point alloy/nano carbon composite material with a three-dimensional conductive network and a preparation method thereof.
  • the main method to improve the conductivity of rubber is to add various conductive fillers to the rubber matrix, such as conductive carbon black, carbon fiber, carbon nanotube, and various metal powders (such as silver powder, copper powder), etc.
  • the main method of addition is The rubber is mixed with the conductive filler through an open mill or an internal mixer. This simple blending process often leads to random dispersion of the filler in the matrix, and the dispersion is very uneven, and the agglomeration is relatively serious, resulting in a larger amount of conductive filler to reach the critical threshold of conductivity. Therefore, how to improve the dispersion of conductive fillers in the matrix, build an optimized three-dimensional conductive network, and reduce the critical threshold of conductivity has become a research goal pursued by many researchers.
  • Chinese invention patent application 201710723740.1 discloses a silicone rubber composite material with enhanced electrical conductivity caused by high-temperature cyclic tensile force and a preparation method thereof.
  • its raw material composition is: silicone rubber raw rubber 40 to 90%, reinforcing agent 5 to 40%, structure control agent 1 to 5%, low melting point alloy 0.5 to 10%, surface modifier 0.5 to 5%, crosslinking agent 1 to 4%.
  • low melting point alloy is blended with raw silicone rubber, reinforcing agent, structure control agent, crosslinking agent, and vulcanized to obtain silicone rubber composite material; the silicone rubber composite material is cyclically stretched at high temperature, The temperature is 100-250°C, the elongation is 100-300%, the stretching rate is 50-200mm ⁇ min -1 , and the number of stretching is 10-1000 times.
  • the invention does not need to increase the amount of conductive filler, and can adjust the conductive performance of the reinforced silicone rubber composite material in a larger range only by high-temperature cyclic stretching, and has little effect on its mechanical properties and transparency.
  • this technology achieves the orientation of low melting point alloys, it can only be oriented along the stretching direction and cannot be formed perpendicular to the stretching direction. Therefore, a three-dimensional conductive path cannot be formed in the rubber matrix and a lower resistivity cannot be achieved. .
  • the conductive performance of the composite material can be adjusted in a wide range.
  • the synergistic effect of carbon nanotubes and low melting point alloys can be fully utilized to significantly improve the conductive performance of the composite material.
  • the rubber/low melting point alloy/nano-carbon composite material with three-dimensional conductive network in terms of mass percentage, its raw material composition is: rubber 60-85%, reinforcing agent 5-15%, vulcanizing agent 0.5-5%, nano-carbon Material 1 ⁇ 5%, low melting point alloy 5 ⁇ 20%;
  • the low melting point alloy is composed of two or more elements of tin, bismuth, indium, gallium, antimony, cadmium and lead; the melting point of the low melting point alloy is 60-150°C, and the particle size is 30-300 ⁇ m ;
  • the rubber is one or more of fluororubber, natural rubber, chloroprene rubber, ethylene propylene rubber, silicone rubber and hydrogenated nitrile rubber.
  • the nano-carbon material is one or more of carbon nanotubes, graphene, carbon nanoribbons and fullerenes,
  • the vulcanizing agent is bis-2,4-dichlorobenzoyl peroxide, dibenzoyl peroxide, dicumyl peroxide and 2,5-dimethyl-2,5-bis( One or more of tert-butyl peroxide) hexane.
  • the reinforcing agent is one or two of precipitated white carbon black and gas phase white carbon black.
  • the metal template is iron plate, steel plate or aluminum alloy plate.
  • the method for preparing the rubber/low melting point alloy/nano-carbon composite material with a three-dimensional conductive network includes the following steps:
  • the rubber/low melting point alloy/nanocarbon blend with a thickness of 1 ⁇ 5mm is placed between two metal templates with smooth and flat surfaces, and then pressed by a plate vulcanizer to form a circle with a thickness of 0.05 ⁇ 0.20mm Thin film, the blend is squeezed and heated from the metal template.
  • the low melting point alloy changes from a spherical shape to a slender fiber shape.
  • the slender fiber shape is oriented along the radius of the circular sheet.
  • the pressing temperature of the plate vulcanizing machine is 70-160°C, the pressing pressure is 5-15 MPa, and the pressing time is 10-30s; and the pressing temperature of the plate vulcanizing machine is higher than that of the low melting point alloy.
  • the melting point is 5 ⁇ 10°C higher; the pressing time of the plate vulcanizer is 60 ⁇ 120s shorter than the scorching time of rubber.
  • the mixing time in step 1) is 10-30 min; the thickness of the sheet is 1-3 mm; and the time for the blend to be parked is 12-24 h.
  • the temperature of the low-pressure vulcanization in step 3) is 60-150°C
  • the pressure is 0.5-2.0 MPa
  • the time is 10-60 min.
  • the present invention has the following two advantages:
  • the three-dimensional conductive network of the rubber composite material can be designed, and the compression will promote the fiberization of the alloy and the tensile orientation.
  • the re-stacking method can realize the spatial connection of the nano-carbon material and the low melting point alloy, and can adjust the density of the conductive network
  • the electrical conductivity of the composite material can be adjusted in a large range, and the volume resistivity change range is (10 2 ⁇ 10 7 ) ⁇ cm.
  • the surface resistivity and volume resistivity tests are carried out in accordance with the GB/T1692-2008 standard, the temperature is (25 ⁇ 5)°C, the humidity is (56 ⁇ 5)%, and the test voltage is 1000V ,
  • the sample size is 100mm (length) ⁇ 100mm (width) ⁇ 1mm (thickness)
  • R s and R v are surface resistance and volume resistance, respectively, according to formula 1 and formula 2 to calculate the surface resistivity ( ⁇ s ) and volume resistance Rate ( ⁇ v ).
  • R s and R v are the surface resistance and volume resistance respectively; the surface resistivity and volume resistivity tests are carried out in accordance with the GB/T 15662-1995 standard, and the temperature is (25 ⁇ 2)°C , Humidity (50 ⁇ 5)%, test voltage is 10V, sample size is 100mm (length) ⁇ 10mm (width) ⁇ 3mm (thickness), calculate surface resistivity ( ⁇ s ) and volume resistance according to formula 3 and formula 4 Rate ( ⁇ v ).
  • the raw material composition of the rubber/low melting point alloy/nano-carbon composite material with a three-dimensional conductive network is: fluorine rubber 77%, dicumyl peroxide 2%, carbon nanotubes 1%, tin-bismuth alloy ( Sn45Bi55, melting point 150°C) 20%;
  • the preparation method of rubber/low melting point alloy/nano-carbon composite material with three-dimensional conductive network includes the following steps:
  • fluororubber/tin-bismuth alloy/carbon nanotube blend with a thickness of 1mm and place it between the two smooth and flat templates of the plate vulcanizing machine, and then press it with the plate vulcanizing machine at a temperature of 160°C.
  • the bonding pressure is 15MPa, and the bonding time is 10s.
  • a fluororubber circular thin film with a thickness of about 0.05mm is prepared, in which the tin-bismuth alloy slender fibers are oriented along the radius of the circular sheet.
  • the thin film is cut into a square along the orientation direction of the alloy fibers into a square with a size of 50 ⁇ 50 mm 2 , and 40 small sheets cut out are stacked up and down, wherein the orientation directions of the alloy fibers in two adjacent sheets cross at 90°.
  • the vulcanization temperature is 150° C.
  • the vulcanization pressure is 2 MPa
  • the vulcanization time is 30 minutes to prepare a fluororubber/tin-bismuth alloy/carbon nanotube composite material with a three-dimensional conductive network.
  • the volume resistivity and surface resistivity of the composite material obtained in this example are shown in Table 1.
  • the raw material composition of the rubber/low melting point alloy/nano-carbon composite material with a three-dimensional conductive network is: 85% fluorine rubber, 2% bis 2,4-dichlorobenzoyl peroxide, and precipitated silica 7%, carbon nanotubes 1%, tin-bismuth-cadmium alloy (Sn26Bi54Cd20, melting point 100°C) 5%.
  • the stacked blocks are put into a flat vulcanizer for compression vulcanization, the vulcanization temperature is 100°C, the vulcanization pressure is 2MPa, and the vulcanization time is 30min, to prepare a fluororubber/tin-bismuth-cadmium alloy/carbon nanotube composite material with a three-dimensional conductive network.
  • the volume resistivity, surface resistivity and tensile strength of this composite material are shown in Table 1.
  • the raw material composition of the rubber/low melting point alloy/nano-carbon composite material with a three-dimensional conductive network is: fluoroelastomer 60%, precipitated silica 13%, dicumyl peroxide 2%, fullerene 5%, tin-bismuth alloy (Sn45Bi55, melting point 150°C) 20%.
  • the preparation method of rubber/low melting point alloy/nano-carbon composite material with three-dimensional conductive network includes the following steps: adding fluorine rubber on an open mill, then adding precipitated silica, fullerene and tin-bismuth alloy (Sn45Bi55), and finally Add dicumyl peroxide, mix for 30 minutes, control the roll temperature to 30°C, take out the sheet with a thickness of 4mm, and leave it for 24 hours to obtain a fluororubber/tin-bismuth alloy/fullerene blend.
  • the thin film was cut into a square along the orientation direction of the alloy fibers, with a size of 300 ⁇ 300 mm 2 , and the cut out 60 small sheets were stacked up and down, wherein the orientation directions of the alloy fibers in the adjacent two sheets crossed at 135°.
  • the vulcanization temperature is 150° C.
  • the vulcanization pressure is 2 MPa
  • the vulcanization time is 30 minutes to prepare a fluororubber/tin-bismuth alloy/fullerene composite material with a three-dimensional conductive network.
  • the volume resistivity and surface resistivity of the composite material obtained in this example are shown in Table 1.
  • the raw material composition of the rubber/low melting point alloy/nano-carbon composite material with a three-dimensional conductive network is: natural rubber 82.5%, dicumyl peroxide 0.5%, carbon nanotubes 2%, tin-bismuth alloy ( Sn45Bi55, melting point 150°C) 15%.
  • the preparation method of the rubber/low melting point alloy/nano-carbon composite material with three-dimensional conductive network includes the following steps: adding natural rubber on an open mill, then adding carbon nanotubes and tin-bismuth alloy (Sn45Bi55), and finally adding diisoperoxide Propylene benzene was mixed for 10 minutes, the roller temperature was controlled to 30°C, the sheet was discharged with a thickness of 3mm, and it was parked for 24 hours to obtain a natural rubber/tin-bismuth alloy/carbon nanotube blend.
  • the thin film is cut into a circle with a diameter of 200 mm along the orientation direction of the alloy fibers, and 20 pieces of cut out are stacked up and down, wherein the orientation directions of the alloy fibers in two adjacent pieces cross at 45°.
  • the stacked blocks are put into a flat vulcanizer for compression vulcanization, the vulcanization temperature is 150° C., the vulcanization pressure is 0.5 MPa, and the vulcanization time is 60 minutes, to prepare a natural rubber/tin-bismuth alloy/carbon nanotube composite material with a three-dimensional conductive network.
  • Table 1 shows the volume resistivity and surface resistivity of the composite material obtained in this example.
  • the raw material composition of the rubber/low melting point alloy/nano-carbon composite material with a three-dimensional conductive network is: ethylene propylene rubber 70%, precipitated silica 11%, dicumyl peroxide 2%, graphene 2%, tin-bismuth alloy (Sn45Bi55, melting point 150°C) 15%.
  • the preparation method of the rubber/low melting point alloy/nano-carbon composite material with three-dimensional conductive network includes the following steps: adding ethylene-propylene rubber on the open mill, then adding graphene and tin-bismuth alloy (Sn45Bi55), and finally adding diisoperoxide Acrylic benzene was mixed for 20 minutes, the temperature of the roll was controlled to 30°C, and the sheet was discharged with a thickness of 3 mm, and then left for 24 hours to obtain an ethylene propylene rubber/tin-bismuth alloy/graphene blend.
  • the stacked blocks are put into a flat vulcanizer for compression vulcanization, the vulcanization temperature is 150° C., the vulcanization pressure is 2 MPa, and the vulcanization time is 60 minutes to prepare an ethylene propylene rubber/tin-bismuth alloy/graphene composite material with a three-dimensional conductive network.
  • the volume resistivity and surface resistivity of the composite material obtained in this example are shown in Table 1.
  • the raw material composition of the rubber/low melting point alloy/nano-carbon composite material with a three-dimensional conductive network is: 60% silicone rubber, 15% fumed silica, 2% dibenzoyl peroxide, carbon nanobelt 5%, tin-lead-bismuth-indium alloy (Sn12Pb18Bi49In21, melting point 60°C) 18%.
  • the preparation method of rubber/low melting point alloy/nano-carbon composite material with three-dimensional conductive network includes the following steps: adding silicon rubber on an open mill, and then adding fumed white carbon black, carbon nanobelt and tin-lead-bismuth-indium alloy (Sn12Pb18Bi49In21) Finally, add dibenzoyl peroxide, mix for 20 minutes, control the roll temperature to 30°C, and discharge the sheet with a thickness of 5mm, and leave it for 24 hours to obtain a silicone rubber/tin-lead-bismuth-indium alloy/carbon nanobelt mixture.
  • the vulcanization temperature is 60°C
  • the vulcanization pressure is 0.5MPa
  • the vulcanization time is 60min.
  • the silicon rubber/tin-lead-bismuth-indium alloy/carbon nanobelt composite with three-dimensional conductive network is prepared material.
  • the volume resistivity and surface resistivity of the composite material obtained in this example are shown in Table 1.
  • the raw material composition of the rubber/low melting point alloy/nano-carbon composite material with a three-dimensional conductive network is: silicone rubber 77%, fumed silica 10%, 2,5-dimethyl-2,5- Bis (tert-butyl peroxide) hexane 2%, graphene 1%, tin-bismuth alloy (Sn45Bi55, melting point 150°C) 10%.
  • the preparation method of rubber/low melting point alloy/nano-carbon composite material with three-dimensional conductive network includes the following steps: adding silicon rubber on an open mill, then adding fumed white carbon black, graphene and tin-bismuth alloy (Sn45Bi55), and finally adding 2,5-Dimethyl-2,5-bis(tert-butylperoxy)hexane, mixed for 30min, controlled roll temperature at 30°C, ejected at a thickness of 2mm, left for 24h to obtain silicone rubber/tin-bismuth alloy /Graphene blend.
  • a round silicone rubber thin film with a thickness of about 0.05 mm is prepared, in which the tin-bismuth alloy slender fibers are oriented along the radius of the round sheet.
  • the thin film is cut into a square along the orientation direction of the alloy fibers, with a size of 200 ⁇ 200mm 2 , and 100 pieces of cut out are stacked up and down, wherein the orientation directions of the alloy fibers in the adjacent two sheets cross at 90°.
  • the stacked blocks are put into a flat vulcanizer for compression vulcanization, the vulcanization temperature is 150° C., the vulcanization pressure is 0.5 MPa, and the vulcanization time is 30 minutes to prepare a silicone rubber/tin-bismuth alloy/graphene composite material with a three-dimensional conductive network.
  • the volume resistivity and surface resistivity of the composite material obtained in this example are shown in Table 1.
  • the raw material composition of the rubber/low melting point alloy/nano-carbon composite material with a three-dimensional conductive network is: neoprene 85%, 2,5-dimethyl-2,5-bis(tert-butyl peroxide) Base) hexane 2%, graphene 1%, tin-bismuth alloy (Sn45Bi55, melting point 150°C) 12%.
  • the preparation method of the rubber/low melting point alloy/nano-carbon composite material with three-dimensional conductive network includes the following steps: adding neoprene on the open mill, then adding graphene and tin-bismuth alloy (Sn45Bi55), and finally adding 2,5- Dimethyl-2,5-bis(tert-butylperoxy)hexane, mixed for 20min, controlled roll temperature at 30°C, ejected at 4mm thickness, parked for 24h, obtained neoprene/tin-bismuth alloy/graphene Blend.
  • neoprene/tin-bismuth alloy/graphene blend Take a 4mm thick neoprene/tin-bismuth alloy/graphene blend and place it between the two smooth and flat templates of the plate vulcanizing machine, and then press it with a plate vulcanizing machine at a temperature of 150°C.
  • the bonding pressure is 10 MPa, and the bonding time is 20 s.
  • a circular neoprene rubber sheet with a thickness of about 0.1 mm is prepared, in which the elongated tin-bismuth alloy fibers are oriented along the radius of the circular sheet.
  • the thin film is cut into a square along the orientation direction of the alloy fibers, with a size of 300 ⁇ 300 mm 2 , and 30 small sheets cut out are stacked up and down, wherein the orientation directions of the alloy fibers in the adjacent two sheets cross at 90°.
  • the vulcanization temperature is 150° C.
  • the vulcanization pressure is 2 MPa
  • the vulcanization time is 50 min, to prepare a neoprene rubber/tin-bismuth alloy/graphene composite material with a three-dimensional conductive network.
  • the volume resistivity and surface resistivity of the composite material obtained in this example are shown in Table 1.
  • the raw material composition of the rubber/low melting point alloy/nano-carbon composite material with a three-dimensional conductive network is: hydrogenated nitrile rubber 80%, precipitated silica 10%, 2,5-dimethyl-2, 5-bis(tert-butylperoxy)hexane 2%, carbon nanotubes 5%, tin-bismuth alloy (Sn45Bi55, melting point 150°C) 3%.
  • the preparation method of rubber/low melting point alloy/nano-carbon composite material with three-dimensional conductive network includes the following steps: adding hydrogenated nitrile rubber on an open mill, and then adding precipitated silica, carbon nanotubes and tin-bismuth alloy (Sn45Bi55) , Finally add 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, mix for 30min, control the roll temperature to 30°C, discharge the sheet with a thickness of 5mm, and park for 24h to obtain hydrogenated butyronitrile Rubber/tin-bismuth alloy/carbon nanotube blend.
  • the pressing pressure is 15MPa
  • the pressing time is 20s
  • a circular thin film with a thickness of about 0.1mm is prepared, in which the tin-bismuth alloy thin fibers are oriented along the radius of the circular sheet.
  • the thin film is cut into a square along the orientation direction of the alloy fibers, with a size of 400 ⁇ 400 mm 2 , and 40 small sheets cut out are stacked on top of each other, wherein the orientation directions of the alloy fibers of two adjacent sheets cross at 90°.
  • the vulcanization temperature is 150°C
  • the vulcanization pressure is 2MPa
  • the vulcanization time is 30min.
  • the hydrogenated nitrile rubber/tin-bismuth alloy/carbon nanotube composite material with three-dimensional conductive network is prepared. .
  • the volume resistivity and surface resistivity of the composite material obtained in this example are shown in Table 1.
  • the raw material composition of fluorine rubber/low melting point alloy/nanocarbon composite material is: fluorine rubber 77%, dicumyl peroxide 2%, carbon nanotubes 1%, tin-bismuth alloy (Sn45Bi55, melting point 150 °C) 20%.
  • Example 1 Compared with Comparative Example, when the nano-carbon material and the same amount of low-melting alloy, in Example 1, the volume resistivity and surface resistivity of the composite material decreased, as compared with Comparative Example, from 1010 ⁇ cm is reduced to 10 6 ⁇ cm, indicating that the use of compression and thinning to promote the tensile orientation of low melting point alloys and the design of stacking methods can effectively form a three-dimensional conductive network of low melting point alloys and nano-carbon materials in the rubber matrix. , Thereby greatly reducing the resistivity of the composite material by 4 orders of magnitude.
  • Example 2 reduces the amount of low melting point alloy from 20% to 5%, while the volume resistivity and surface resistivity are only increased by one order of magnitude, indicating that the percolation threshold of conductivity is significantly reduced.
  • Example 3 by increasing the amount of nano-carbon material and low melting point alloy, the three-dimensional conductive network formed in the composite material is denser, so the volume resistivity of the composite material reaches the lowest value, about 6.3 ⁇ 10 2 ⁇ cm.
  • Examples 4 to 8 selected natural rubber, ethylene propylene rubber, silicone rubber, chloroprene rubber and hydrogenated nitrile rubber, etc. It can be seen that the volume resistivity of the composite material is between 10 3 ⁇ 10 6 ⁇ cm, The electrical conductivity is significantly improved, indicating that the method of the present invention has a wider application range.
  • the tensile orientation of the low melting point alloy occurs during the high temperature stretching process of the vulcanized rubber. Due to the limited high temperature elongation of the rubber, the degree of fiberization of the alloy is not high, and the average length and diameter are relatively low ( ⁇ 10) Therefore, the conductivity is not significantly improved (the lowest volume resistivity is 10 6 ⁇ cm); the low melting point alloy orientation of the present invention occurs during the pressing process of unvulcanized rubber, because the film thickness is very thin (about 0.05mm) Therefore, the fiberization of the alloy is very significant, and the average long diameter is relatively large (>50), so the fiberized low-melting alloy is easier to form a conductive path.
  • the conductive filler is at a lower critical threshold to achieve low resistivity, and the amount of carbon nanofiller is not more than 5wt%, and the volume resistivity of rubber can be achieved as low as 10 2 ⁇ cm, which meets high conductivity.
  • carbon nanomaterials amount to more than 10wt%, in order to achieve the fluorine rubber volume resistivity of the order of 102.
  • the most notable feature of the present invention is to construct a three-dimensional conductive path.
  • the number of layers of the conductive diaphragm is designed to change, in a larger range (10 2 ⁇ 10 7 ⁇ cm ) Adjusting resistivity, this conductive composite material has excellent electrical properties and is expected to be used in wearable devices, electronic skins, flexible sensors and other fields.

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Abstract

具有三维导电网络的橡胶/低熔点合金/纳米碳复合材料及其制备方法。以质量百分比计，其原料组成为橡胶60～85％、补强剂5～15％、硫化剂0.5～5％、纳米碳材料1～5％、低熔点合金5～20％。制备时先将橡胶、补强剂、低熔点合金、纳米碳材料和硫化剂在橡胶开炼机中进行混合，在高于低熔点合金熔点的压合温度下压合，使低熔点合金纤维化并发生取向，将制得的薄胶片沿着合金纤维的取向方向裁剪，上下堆叠，低压硫化。无需大量添加导电填料的情况下，仅通过压合取向和重新堆叠构建橡胶/低熔点合金/纳米碳复合材料的三维导电网络，在较大范围内可调控复合材料的导电性能，大大降低了导电的逾渗阈值。

Description

具有三维导电网络的橡胶/低熔点合金/纳米碳复合材料及其制备方法 技术领域
本发明涉及一种橡胶复合材料，更具体地说是涉及一种具有三维导电网络的橡胶/低熔点合金/纳米碳复合材料及其制备方法。
背景技术
近年来，基于弹性体的可穿戴电子设备、电子皮肤、柔性传感器、超级电容器、电磁屏蔽材料发展迅猛，使导电橡胶复合材料逐渐成为国内外的研究热点。然而，大部分橡胶是绝缘材料，其体积电阻率通常大于10 12Ω·cm。因此，必须对橡胶进行配方设计和填充改性，才能够提高橡胶复合材料的导电性能。
目前，改善橡胶导电性的方法主要是往橡胶基体中添加各种导电填料，如导电炭黑、碳纤维、碳纳米管以及各种金属粉体(如银粉、铜粉)等，添加的方法主要是通过开炼机或密炼机使橡胶与导电填料混合。这种简单共混工艺常导致填料在基体中的无规分散，且分散很不均匀，团聚比较严重，造成导电填料需要较大用量才能达到导电的临界阈值。因此，如何提高导电填料在基体中的分散，构建优化的三维导电网络，降低导电的临界阈值，成为众多研究者不断追求的研究目标。
例如，中国发明专利申请201710723740.1公开了高温循环拉伸力致导电性能增强的硅橡胶复合材料及其制备方法，以质量百分比计，其原料组成为：硅橡胶生胶40～90％，补强剂5～40％，结构控制剂1～5％，低熔点合金0.5～10％，表面改性剂0.5～5％，交联剂1～4％。低熔点合金在进行表面改性后，与硅橡胶生胶、补强剂、结构控制剂、交联剂共混、硫化后，制得硅橡胶复合材料；对硅橡胶复合材料高温循环拉伸，温度100～250℃、伸长率100～300％、拉伸速率50～200mm·min -1、拉伸次数10～1000次。本发明无需增加导电填料的用量，仅仅通过高温循环拉伸的方式可在较大范围内调整增强硅橡胶复合材料的导电性能，对其力学性能和透明性影响很小。虽然该技术实现了低熔点合金的取向，但是由于只能沿着拉伸方向取向，而垂直于拉伸方向取向无法形成，因而在橡胶基体中无法构成三维导电通路，无法达到更低的电阻率。
发明内容
本发明的目的在于提供一种在橡胶基体中构成三维导电通路的橡胶/低熔点合金/纳米 碳复合材料及其制备方法，该方法在较大范围内可调控复合材料的导电性能，其体积电阻率范围为10 2～10 7Ω·cm。
本发明首先将橡胶与低熔点合金和纳米碳材料混合，制备橡胶/低熔点合金/纳米碳材料共混物，然后通过压合方式将复合材料压成圆形薄片，使低熔点合金沿着圆形薄片的半径方向发生取向，沿着低熔点合金的取向方向在圆形薄片上裁切出直径为50～500mm的圆形薄片或边长为50～500mm的正方形薄片，然后将薄片进行上下堆叠，使得相邻两片的取向方向按一定角度交叉排列，同时利用纳米碳材料在基体中的无规分散，实现纳米碳材料与取向的低熔点合金纤维的三维搭接，构建三维导电网络通路，根据导电网络的疏密程度，使复合材料的导电性能在较宽范围内可调，此外，可充分利用碳纳米管和低熔点合金的协同效应，明显改善复合材料的导电性能。
本发明上述目的通过以下技术方案实现：
的具有三维导电网络的橡胶/低熔点合金/纳米碳复合材料：以质量百分比计，其原料组成为：橡胶60～85％、补强剂5～15％、硫化剂0.5～5％、纳米碳材料1～5％、低熔点合金5～20％；
所述的低熔点合金由锡、铋、铟、镓、锑、镉和铅中的两种或多种元素组成；所述的低熔点合金的熔点为60～150℃，粒径为30～300μm；
制备时，先将橡胶与低熔点合金和纳米碳材料混合，制备橡胶/低熔点合金/纳米碳材料共混物，然后将橡胶/低熔点合金/纳米碳共混物置于两块表面光滑平整的金属模板之间，随后用平板硫化机进行压合，压成厚度为0.05～0.20mm的圆形薄胶片，使低熔点合金由球形变成细长纤维状，细长纤维状沿着圆形薄片半径方向取向；将制得的薄胶片沿着合金纤维的取向方向裁剪成直径为50～500mm的圆形薄片或边长为50～500mm的正方形薄片，上下堆叠一起，使得任何相邻两块的合金纤维取向方向交叉成45～135°角度，控制堆叠的片层数为5～100层；再低压硫化，制得具有三维导电网络的橡胶/低熔点合金/纳米碳复合材料。
为进一步实现本发明目的，优选地，所述的橡胶为氟橡胶、天然橡胶、氯丁橡胶、乙丙橡胶、硅橡胶和氢化丁腈橡胶中的一种或多种。
优选地，所述的纳米碳材料为碳纳米管、石墨烯、碳纳米带和富勒烯中的一种或多种，
优选地，所述的硫化剂为过氧化双2,4-二氯苯甲酰、过氧化二苯甲酰、过氧化二异丙苯和2,5-二甲基-2,5-双(过氧化叔丁基)己烷中的一种或多种。
优选地，所述的补强剂为沉淀白炭黑、气相白炭黑中的一种或两种。
优选地，所述的金属模板为铁板、钢板或铝合金板。
所述具有三维导电网络的橡胶/低熔点合金/纳米碳复合材料的制备方法，包括以下步骤：
1)橡胶/低熔点合金/纳米碳共混物的制备
在橡胶开炼机上加入橡胶，包辊，然后加入补强剂、低熔点合金和纳米碳材料，再加入硫化剂，混炼，出片，将共混物停放；得橡胶/低熔点合金/纳米碳共混物；
2)橡胶基体内三维导电网络的构建
将厚度为1～5mm的橡胶/低熔点合金/纳米碳共混物置于两块表面光滑平整的金属模板之间，随后用平板硫化机进行压合，压成厚度为0.05～0.20mm的圆形薄胶片，共混物受到来自金属模板的挤压和加热作用，低熔点合金由球形变成细长纤维状，细长纤维状沿着圆形薄片半径方向取向，将制得的薄胶片沿着合金纤维的取向方向裁剪成直径为50～500mm的圆形薄片或边长为50～500mm的正方形薄片，将薄片上下堆叠，使得任何相邻两块的合金纤维取向方向交叉成45～135°角度，堆叠的片层数为5～100层；
3)橡胶/低熔点合金/纳米碳复合材料的硫化
将堆叠好的多层胶片放入平板硫化机进行低压硫化，制得具有三维导电网络的橡胶/低熔点合金/纳米碳复合材料。
8、优选地，步骤2)中平板硫化机压合的温度为70～160℃，压合的压力5～15MPa，压合的时间10～30s；且平板硫化机压合的温度比低熔点合金的熔点高5～10℃；平板硫化机压合的时间比橡胶的焦烧时间短60～120s。
优选地，步骤1)所述的混炼的时间为10～30min；出片厚度为1～3mm；所述的共混物停放的时间为12～24h。
优选地，步骤3)中所述的低压硫化的温度为60～150℃，压力为0.5～2.0MPa，时间为10～60min。
本发明通过往橡胶中加入少量的低熔点合金和纳米碳材料形成共混物，然后用平板硫化机对共混物进行压合，形成具有规则取向结构的低熔点合金纤维，而纳米碳材料由于尺寸太小(纳米级)，无法通过压合取向，仍然保持无规分散状态。然后再将薄胶片沿着低熔点合金的取向方向进行裁切成圆形或正方形，然后将裁成的多块小薄片上下堆叠，使相邻两片之间合金纤维的取向方向互相交叉成45～135°角度。最后在平板硫化机上将堆叠块进行低压硫化，制得具有三维导电网络的橡胶/低熔点合金/纳米碳复合材料。
与现有技术相比，本发明具有以下两个方面的优点：
(1)橡胶复合材料的三维导电网络可以设计，压合促使合金纤维化，并发生拉伸取向，采用重新堆叠方式实现纳米碳材料和低熔点合金在空间连通，并能调整导电网络的疏密程度，实现复合材料的导电性能在较大范围内可以调控，其体积电阻率变化范围为(10 2～10 7) Ω·cm。
(2)利用低熔点合金和纳米碳材料的杂化作用，发挥低熔点合金和纳米碳材料的协同效应，明显降低导电填料的逾渗阈值，使复合材料在较低的导电填料用量时达到高电导率。而以往通过机械共混方法制备的橡胶/导电填料复合材料，由于导电填料在基体内的无规分布以及导电填料的严重团聚，导致复合材料的导电逾渗阈值很高。
具体实施方式
为更好的理解本发明，下面结合实施例进一步说明本发明，但实施例不构成对本发明保护范围的限制。
下面实施例和对比例有关测试方法说明如下：
当复合材料的电阻高于10 6Ω时，表面电阻率和体积电阻率测试按照GB/T1692-2008标准进行，温度为(25±5)℃，湿度(56±5)％，测试电压为1000V，样品规格为100mm(长)×100mm(宽)×1mm(厚)，R s和R v分别为表面电阻和体积电阻，根据公式1和公式2分别计算表面电阻率(ρ s)和体积电阻率(ρ v)。
ρ s＝R s2π/(㏑D 2/D 1)＝80R s(Ω)   (1)
ρ v＝(R vπr 2)/d＝196.3R v(Ω·cm)   (2)
其中，r：测试电极的半径(2.5cm)，d：绝缘材料试样的厚度(1mm)，D 2：保护电极内径(5.4cm)，D 1：测试直径(5cm)。
当复合材料的电阻低于10 6Ω时，R s和R v分别为表面电阻和体积电阻；表面电阻率和体积电阻率测试按照GB/T 15662-1995标准进行，温度(25±2)℃，湿度(50±5)％，测试电压为10V，样品规格为100mm(长)×10mm(宽)×3mm(厚)，根据公式3和公式4分别计算表面电阻率(ρ s)和体积电阻率(ρ v)。
ρ s＝R sd/l   (3)
ρ v＝R vL/S   (4)
其中，d：平行电极间的距离，cm；l：平行电极的长度，cm；L：两电压电极间的距离，cm；S：垂直电流的试样截面积，cm 2。
实施例1
以质量百分比计，具有三维导电网络的橡胶/低熔点合金/纳米碳复合材料的原料组分组成为：氟橡胶77％、过氧化二异丙苯2％、碳纳米管1％、锡铋合金(Sn45Bi55，熔点150℃)20％；
具有三维导电网络的橡胶/低熔点合金/纳米碳复合材料的制备方法，包括以下步骤：
在开炼机上加入氟橡胶，然后加入碳纳米管以及锡铋合金(Sn45Bi55)，最后加入过氧化二异丙苯，混炼20min，控制辊温为30℃，以1mm厚度出片，停放24h，得氟橡胶/锡铋合金/碳纳米管共混物。
取厚度为1mm的氟橡胶/锡铋合金/碳纳米管共混物放置在平板硫化机的两块光滑平整的模板之间，随后用平板硫化机进行压合，压合温度为160℃，压合压力为15MPa，压合时间为10s，制得厚度约为0.05mm的氟橡胶圆形薄胶片，其中锡铋合金细长纤维沿圆形薄片的半径方向发生取向。将薄胶片沿合金纤维的取向方向进行裁剪成正方形，尺寸为50×50mm 2，并将裁出的40块小薄片进行上下堆叠，其中相邻两片中合金纤维的取向方向交叉成90°。
将堆叠块放入平板硫化机进行压合硫化，硫化温度为150℃，硫化压力2MPa，硫化时间为30min，制得具有三维导电网络的氟橡胶/锡铋合金/碳纳米管复合材料。本实施例所得复合材料的体积电阻率和表面电阻率如表1所示。
实施例2
以质量百分比计，具有三维导电网络的橡胶/低熔点合金/纳米碳复合材料的原料组分组成为：氟橡胶85％、过氧化双2,4-二氯苯甲酰2％、沉淀白炭黑7％、碳纳米管1％、锡铋镉合金(Sn26Bi54Cd20，熔点100℃)5％。
具有三维导电网络的橡胶/低熔点合金/纳米碳复合材料的制备方法，包括以下步骤：在开炼机上加入氟橡胶，然后加入沉淀白炭黑、碳纳米管以及锡铋镉合金(Sn26Bi54Cd20)，最后加入过氧化双2,4-二氯苯甲酰，混炼30min，控制辊温为30℃，以3mm厚度出片，停放12h，得氟橡胶/锡铋镉合金/碳纳米管共混物。
取厚度为3mm的氟橡胶/锡铋镉合金/碳纳米管共混物放置在平板硫化机的两块光滑平整的模板之间，随后用平板硫化机进行压合，压合温度为110℃，压合压力15MPa，压合时间为10s，制得厚度约为0.05mm的氟橡胶圆形薄胶片，其中锡铋镉合金细长纤维沿圆形薄片的半径方向发生取向。将薄胶片沿着合金纤维的取向方向裁剪成圆形，直径为100mm，并将裁出的30块小薄片上下堆叠，其中相邻两片中合金纤维的取向方向交叉成45°。
将堆叠块放入平板硫化机进行压合硫化，硫化温度为100℃，硫化压力为2MPa，硫化时间为30min，制得具有三维导电网络的氟橡胶/锡铋镉合金/碳纳米管复合材料。此复合材料的体积电阻率和表面电阻率和拉伸强度如表1所示。
实施例3
以质量百分比计，具有三维导电网络的橡胶/低熔点合金/纳米碳复合材料的原料组分组 成为：氟橡胶60％、沉淀白炭黑13％、过氧化二异丙苯2％、富勒烯5％、锡铋合金(Sn45Bi55，熔点150℃)20％。
具有三维导电网络的橡胶/低熔点合金/纳米碳复合材料的制备方法，包括以下步骤：在开炼机上加入氟橡胶，然后加入沉淀白炭黑、富勒烯以及锡铋合金(Sn45Bi55)，最后加入过氧化二异丙苯，混炼30min，控制辊温为30℃，以4mm厚度出片，停放24h，得氟橡胶/锡铋合金/富勒烯共混物。
取厚度4mm的氟橡胶/锡铋合金/富勒烯共混物放置在平板硫化机的两块光滑平整的模板之间，随后用平板硫化机进行压合，压合温度为160℃，压合压力为15MPa，压合时间为20s，制得厚度约为0.05mm的氟橡胶圆形薄胶片，其中锡铋合金细长纤维沿圆形薄片的半径方向发生取向。将薄胶片沿着合金纤维的取向方向裁剪成正方形，尺寸为300×300mm 2，并将裁出的60块小薄片上下堆叠，其中相邻两片中合金纤维的取向方向交叉成135°。
将堆叠块放入平板硫化机进行压合硫化，硫化温度为150℃，硫化压力为2MPa，硫化时间为30min，制得具有三维导电网络的氟橡胶/锡铋合金/富勒烯复合材料。本实施例所得复合材料的体积电阻率和表面电阻率如表1所示。
实施例4
以质量百分比计，具有三维导电网络的橡胶/低熔点合金/纳米碳复合材料的原料组分组成为：天然橡胶82.5％、过氧化二异丙苯0.5％、碳纳米管2％、锡铋合金(Sn45Bi55，熔点150℃)15％。
具有三维导电网络的橡胶/低熔点合金/纳米碳复合材料的制备方法，包括以下步骤：在开炼机上加入天然橡胶，然后加入碳纳米管以及锡铋合金(Sn45Bi55)，最后加入过氧化二异丙苯，混炼10min，控制辊温为30℃，以3mm厚度出片，停放24h，得天然橡胶/锡铋合金/碳纳米管共混物。
将厚度为3mm的天然橡胶/锡铋合金/碳纳米管共混物放置在平板硫化机的两块光滑平整的模板之间，随后用平板硫化机进行压合，压合温度为160℃，压合压力为15MPa，压合时间为10s，制得厚度约为0.10mm的氟橡胶圆形薄胶片，其中锡铋合金细长纤维沿圆形薄片的半径方向发生取向。
将薄胶片沿着合金纤维的取向方向裁剪成圆形，直径为200mm，并将裁出的20块小薄片上下堆叠，其中相邻两块中合金纤维的取向方向交叉成45°。将堆叠块放入平板硫化机进行压合硫化，硫化温度为150℃，硫化压力为0.5MPa，硫化时间为60min，制得具有三维导电网络的天然橡胶/锡铋合金/碳纳米管复合材料。本实施例所得复合材料的体积电阻率 和表面电阻率如表1所示。
实施例5
以质量百分比计，具有三维导电网络的橡胶/低熔点合金/纳米碳复合材料的原料组分组成为：乙丙橡胶70％、沉淀白炭黑11％、过氧化二异丙苯2％、石墨烯2％、锡铋合金(Sn45Bi55，熔点150℃)15％。
具有三维导电网络的橡胶/低熔点合金/纳米碳复合材料的制备方法，包括以下步骤：在开炼机上加入乙丙橡胶，然后加入石墨烯以及锡铋合金(Sn45Bi55)，最后加入过氧化二异丙苯，混炼20min，控制辊温为30℃，以3mm厚度出片，停放24h，得乙丙橡胶/锡铋合金/石墨烯共混物。
取厚度为3mm的乙丙橡胶/锡铋合金/石墨烯共混物放置在平板硫化机的两块光滑平整的模板之间，随后用平板硫化机进行压合，压合温度为150℃，压合压力为15MPa，压合时间为20s，制得厚度约为0.2mm的乙丙橡胶圆形薄胶片，其中锡铋合金细长纤维沿圆形薄片的半径方向发生取向。将薄胶片沿着合金纤维的取向方向裁剪成圆形，直径为200mm，并将裁出的5块小薄片上下堆叠，其中相邻两片中合金纤维的取向方向交叉成90°。
将堆叠块放入平板硫化机进行压合硫化，硫化温度为150℃，硫化压力为2MPa，硫化时间为60min，制得具有三维导电网络的乙丙橡胶/锡铋合金/石墨烯复合材料。本实施例所得复合材料的体积电阻率和表面电阻率如表1所示。
实施例6
以质量百分比计，具有三维导电网络的橡胶/低熔点合金/纳米碳复合材料的原料组分组成为：硅橡胶60％、气相白炭黑15％、过氧化二苯甲酰2％、碳纳米带5％、锡铅铋铟合金(Sn12Pb18Bi49In21，熔点60℃)18％。
具有三维导电网络的橡胶/低熔点合金/纳米碳复合材料的制备方法，包括以下步骤：在开炼机上加入硅橡胶，然后加入气相白炭黑、碳纳米带以及锡铅铋铟合金(Sn12Pb18Bi49In21)，最后加入过氧化二苯甲酰，混炼20min，控制辊温为30℃，以5mm厚度出片，停放24h，得硅橡胶/锡铅铋铟合金/碳纳米带混合物。
将厚度为5mm的硅橡胶/锡铅铋铟合金/碳纳米带混合物放置在平板硫化机的两块光滑平整的模板之间，随后用平板硫化机进行压合，压合温度为70℃，压合压力为15MPa，压合时间为10s，制得厚度约为0.05mm的硅橡胶圆形薄胶片，其中锡铅铋铟合金细长纤维沿圆形薄片的半径方向发生取向。将薄胶片沿着合金纤维的取向方向裁剪成圆形，直径为400mm，并将裁出的100块小薄片上下堆叠，其中相邻两片的合金纤维的取向方向交叉成 135°。
将堆叠块放入平板硫化机进行压合硫化，硫化温度为60℃，硫化压力为0.5MPa，硫化时间为60min，制得具有三维导电网络的硅橡胶/锡铅铋铟合金/碳纳米带复合材料。本实施例所得复合材料的体积电阻率和表面电阻率如表1所示。
实施例7
以质量百分比计，具有三维导电网络的橡胶/低熔点合金/纳米碳复合材料的原料组分组成为：硅橡胶77％、气相白炭黑10％、2,5-二甲基-2,5-双(过氧化叔丁基)己烷2％、石墨烯1％、锡铋合金(Sn45Bi55，熔点150℃)10％。
具有三维导电网络的橡胶/低熔点合金/纳米碳复合材料的制备方法，包括以下步骤：在开炼机上加入硅橡胶，然后加入气相白炭黑、石墨烯以及锡铋合金(Sn45Bi55)，最后加入2,5-二甲基-2,5-双(过氧化叔丁基)己烷，混炼30min，控制辊温为30℃，以2mm厚度出片，停放24h，得硅橡胶/锡铋合金/石墨烯共混物。
将厚度为2mm的硅橡胶/锡铋合金/石墨烯共混物放置在平板硫化机的两块光滑平整的模板之间，随后用平板硫化机进行压合，压合温度为160℃，压合压力为15MPa，压合时间为20s，制得厚度约为0.05mm的硅橡胶圆形薄胶片，其中锡铋合金细长纤维沿圆形薄片的半径方向发生取向。将薄胶片沿着合金纤维的取向方向裁剪成正方形，尺寸为200×200mm 2，并将裁出的100块小薄片上下堆叠，其中相邻两片中合金纤维的取向方向交叉成90°。
将堆叠块放入平板硫化机进行压合硫化，硫化温度为150℃，硫化压力为0.5MPa，硫化时间为30min，制得具有三维导电网络的硅橡胶/锡铋合金/石墨烯复合材料。本实施例所得复合材料的体积电阻率和表面电阻率如表1所示。
实施例8
以质量百分比计，具有三维导电网络的橡胶/低熔点合金/纳米碳复合材料的原料组分组成为：氯丁橡胶85％、2,5-二甲基-2,5-双(过氧化叔丁基)己烷2％、石墨烯1％、锡铋合金(Sn45Bi55，熔点150℃)12％。
具有三维导电网络的橡胶/低熔点合金/纳米碳复合材料的制备方法，包括以下步骤：在开炼机上加入氯丁橡胶，然后加入石墨烯以及锡铋合金(Sn45Bi55)，最后加入2,5-二甲基-2,5-双(过氧化叔丁基)己烷，混炼20min，控制辊温为30℃，以4mm厚度出片，停放24h，得氯丁橡胶/锡铋合金/石墨烯共混物。
取厚度为4mm的氯丁橡胶/锡铋合金/石墨烯共混物放置在平板硫化机的两块光滑平整 的模板之间，随后用平板硫化机进行压合，压合温度为150℃，压合压力为10MPa，压合时间为20s，制得厚度约为0.1mm的氯丁橡胶圆形薄胶片，其中锡铋合金细长纤维沿圆形薄片的半径方向发生取向。将薄胶片沿着合金纤维的取向方向裁剪成正方形，尺寸为300×300mm 2，并将裁出的30块小薄片上下堆叠，其中相邻两片中合金纤维的取向方向交叉成90°。
将堆叠块放入平板硫化机进行压合硫化，硫化温度为150℃，硫化压力为2MPa，硫化时间为50min，制得具有三维导电网络的氯丁橡胶/锡铋合金/石墨烯复合材料。本实施例所得复合材料的体积电阻率和表面电阻率如表1所示。
实施例9
以质量百分比计，具有三维导电网络的橡胶/低熔点合金/纳米碳复合材料的原料组分组成为：氢化丁腈橡胶80％、沉淀白炭黑10％、2,5-二甲基-2,5-双(过氧化叔丁基)己烷2％、碳纳米管5％、锡铋合金(Sn45Bi55，熔点150℃)3％。
具有三维导电网络的橡胶/低熔点合金/纳米碳复合材料的制备方法，包括以下步骤：在开炼机上加入氢化丁腈橡胶，然后加入沉淀白炭黑、碳纳米管以及锡铋合金(Sn45Bi55)，最后加入2,5-二甲基-2,5-双(过氧化叔丁基)己烷，混炼30min，控制辊温为30℃，以5mm厚度出片，停放24h，得氢化丁腈橡胶/锡铋合金/碳纳米管共混物。
将厚度为5mm的氢化丁腈橡胶/锡铋合金/碳纳米管共混物放置在平板硫化机的两块光滑平整的模板之间，随后用平板硫化机进行压合，压合温度为160℃，压合压力为15MPa，压合时间为20s，制得厚度约为0.1mm的圆形薄胶片，其中锡铋合金细长纤维沿圆形薄片的半径方向发生取向。将薄胶片沿着合金纤维的取向方向裁剪成正方形，尺寸为400×400mm 2，并将裁出的40块小薄片上下堆叠，其中相邻两片的合金纤维的取向方向交叉成90°。
将堆叠块放入平板硫化机进行压合硫化，硫化温度为150℃，硫化压力为2MPa，硫化时间为30min，制得具有三维导电网络的氢化丁腈橡胶/锡铋合金/碳纳米管复合材料。本实施例所得复合材料的体积电阻率和表面电阻率如表1所示。
对比例
以质量百分比计，氟橡胶/低熔点合金/纳米碳复合材料的原料组分组成为：氟橡胶77％，过氧化二异丙苯2％，碳纳米管1％，锡铋合金(Sn45Bi55，熔点150℃)20％。
在开炼机上加入氟橡胶，然后加入碳纳米管以及锡铋合金(Sn45Bi55)，最后加入过氧化二异丙苯，混炼20min，控制辊温为30℃，出片，停放24h。将共混物放入平板硫化机 中进行硫化，硫化温度为150℃，硫化压力为10MPa，硫化时间为20min，制得氟橡胶/锡铋合金/碳纳米管复合材料，厚度为1mm。本对比例所得复合材料的体积电阻率和表面电阻率如表1所示。
表1橡胶/低熔点合金/纳米碳复合材料的体积电阻率和表面电阻率
Figure PCTCN2019111526-appb-000001
由表1可知，与对比例相比，当纳米碳材料和低熔点合金用量相同时，实施例1中，复合材料的体积电阻率和表面电阻率明显降低，与对比例相比，从10 10Ω·cm降低到10 6Ω·cm，表明采用压合减薄促使低熔点合金的拉伸取向以及设计堆叠方式等办法，能有效在橡胶基体中形成低熔点合金和纳米碳材料的三维导电网络，从而使复合材料的电阻率大幅度降低4个数量级。实施例2与实施例1相比，将低熔点合金的用量从20％降低至5％，而体积电阻率和表面电阻率只提高了1个数量级，表明导电的逾渗阈值明显降低。实施例3中，通过增加纳米碳材料和低熔点合金的用量，复合材料中形成的三维导电网络更加致密，因此复合材料的体积电阻率达到最低值，约为6.3×10 2Ω·cm。实施例4～8分别选用天然橡胶、乙丙橡胶、硅橡胶、氯丁橡胶和氢化丁腈橡胶等品种，可以看出复合材料的体积电阻率介于10 3～10 6Ω·cm之间，导电性能明显改善，表明本发明方法的应用范围较广。
在发明专利201710723740.1中，低熔点合金的拉伸取向发生在硫化橡胶的高温拉伸过程中，由于橡胶的高温伸长率有限，因而合金的纤维化程度不高，平均长径比较低(<10)，因而导电性能提高并不明显(最低体积电阻率为10 6Ω·cm)；而本发明的低熔点合金取向是发生在未硫化橡胶的压合过程中，由于胶片厚度很薄(约0.05mm)，因而合金的纤维化非 常显著，平均长径比较大(>50)，因而纤维化的低熔点合金也更加容易形成导电通路。因此，导电填料处于较低的临界阈值实现低电阻率，碳纳米填料用量不超过5wt％，即可实现橡胶的体积电阻率最低为10 2Ω·cm，满足高导电性，而通常碳纳米材料的用量要超过10wt％，才能使氟橡胶达到10 2数量级的体积电阻率。
本发明最显著的特点是构建三维空间的导电通路，通过发挥碳纳米材料和低熔点合金的协同效应，设计改变导电膜片的层数，在较大范围内(10 2～10 7Ω·cm)调节电阻率，这种导电复合材料的电性能优异，有望应用于可穿戴设备、电子皮肤、柔性传感器等领域。
本发明的上述实施例仅仅是为清楚地说明本发明所作的举例，而并非是对本发明的实施方式的限定。对于所属领域的技术人员来说，在任何未背离本发明的精神实质与原理下所作的改变、修饰、替代、组合、简化，均应为等效的置换方式，都包含在本发明的保护范围之内。

Claims (10)

  1. 具有三维导电网络的橡胶/低熔点合金/纳米碳复合材料，其特征在于，以质量百分比计，其原料组成为：橡胶60～85％、补强剂5～15％、硫化剂0.5～5％、纳米碳材料1～5％、低熔点合金5～20％；
    所述的低熔点合金由锡、铋、铟、镓、锑、镉和铅中的两种或多种元素组成；所述的低熔点合金的熔点为60～150℃，粒径为30～300μm；
    制备时，先将橡胶与低熔点合金和纳米碳材料混合，制备橡胶/低熔点合金/纳米碳材料共混物，然后将橡胶/低熔点合金/纳米碳共混物置于两块表面光滑平整的金属模板之间，随后用平板硫化机进行压合，压成厚度为0.05～0.20mm的圆形薄胶片，使低熔点合金由球形变成细长纤维状，细长纤维状沿着圆形薄片半径方向取向；将制得的薄胶片沿着合金纤维的取向方向裁剪成直径为50～500mm的圆形薄片或边长为50～500mm的正方形薄片，上下堆叠一起，使得任何相邻两块的合金纤维取向方向交叉成45～135°角度，控制堆叠的片层数为5～100层；再低压硫化，制得具有三维导电网络的橡胶/低熔点合金/纳米碳复合材料。
  2. 根据权利要求1所述的具有三维导电网络的橡胶/低熔点合金/纳米碳复合材料，其特征在于：所述的橡胶为氟橡胶、天然橡胶、氯丁橡胶、乙丙橡胶、硅橡胶和氢化丁腈橡胶中的一种或多种。
  3. 根据权利要求1所述的具有三维导电网络的橡胶/低熔点合金/纳米碳复合材料，其特征在于：所述的纳米碳材料为碳纳米管、石墨烯、碳纳米带和富勒烯中的一种或多种，
  4. 根据权利要求1所述的具有三维导电网络的橡胶/低熔点合金/纳米碳复合材料，其特征在于：所述的硫化剂为过氧化双2,4-二氯苯甲酰、过氧化二苯甲酰、过氧化二异丙苯和2,5-二甲基-2,5-双(过氧化叔丁基)己烷中的一种或多种。
  5. 根据权利要求1所述的具有三维导电网络的橡胶/低熔点合金/纳米碳复合材料，其特征在于，所述的补强剂为沉淀白炭黑、气相白炭黑中的一种或两种。
  6. 根据权利要求1所述的具有三维导电网络的橡胶/低熔点合金/纳米碳复合材料，其特征在于，所述的金属模板为铁板、钢板或铝合金板。
  7. 权利要求1-6任一项所述具有三维导电网络的橡胶/低熔点合金/纳米碳复合材料的制备方法，其特征在于包括以下步骤：
    1)橡胶/低熔点合金/纳米碳共混物的制备
    在橡胶开炼机上加入橡胶，包辊，然后加入补强剂、低熔点合金和纳米碳材料，再加入硫化剂，混炼，出片，将共混物停放；得橡胶/低熔点合金/纳米碳共混物；
    2)橡胶基体内三维导电网络的构建
    将厚度为1～5mm的橡胶/低熔点合金/纳米碳共混物置于两块表面光滑平整的金属模板之间，随后用平板硫化机进行压合，压成厚度为0.05～0.20mm的圆形薄胶片，共混物受到来自金属模板的挤压和加热作用，低熔点合金由球形变成细长纤维状，细长纤维状沿着圆形薄片半径方向取向，将制得的薄胶片沿着合金纤维的取向方向裁剪成直径为50～500mm的圆形薄片或边长为50～500mm的正方形薄片，将薄片上下堆叠，使得任何相邻两块的合金纤维取向方向交叉成45～135°角度，堆叠的片层数为5～100层；
    3)橡胶/低熔点合金/纳米碳复合材料的硫化
    将堆叠好的多层胶片放入平板硫化机进行低压硫化，制得具有三维导电网络的橡胶/低熔点合金/纳米碳复合材料。
  8. 根据权利要求7所述的具有三维导电网络的橡胶/低熔点合金/纳米碳复合材料的制备方法，其特征在于：步骤2)中平板硫化机压合的温度为70～160℃，压合的压力5～15MPa，压合的时间10～30s；且平板硫化机压合的温度比低熔点合金的熔点高5～10℃；平板硫化机压合的时间比橡胶的焦烧时间短60～120s。
  9. 根据权利要求7所述的具有三维导电网络的橡胶/低熔点合金/纳米碳复合材料的制备方法，其特征在于：步骤1)所述的混炼的时间为10～30min；出片厚度为1～3mm；所述的共混物停放的时间为12～24h。
  10. 根据权利要求7所述的具有三维导电网络的橡胶/低熔点合金/纳米碳复合材料的制备方法，其特征在于：步骤3)中所述的低压硫化的温度为60～150℃，压力为0.5～2.0MPa，时间为10～60min。
PCT/CN2019/111526 2019-04-15 2019-10-16 具有三维导电网络的橡胶/低熔点合金/纳米碳复合材料及其制备方法 WO2020211311A1 (zh)

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