Preparation method and application of carbon nanotube conductive master batch

Abstract

The invention relates to a preparation method and application of a carbon nanotube conductive master batch, and belongs to the technical field of carbon nanotube conductive master batches. The preparation method of the carbon nanotube conductive master batch comprises the following steps: stirring and mixing a silane coupling agent, a solvent and an organic tin catalyst, spraying the mixture on the surface of a carbon nanotube, carrying out heat preservation treatment, purifying and drying, placing the carbon nanotube in absolute ethyl alcohol for ultrasonic treatment, adding a reaction monomer and an initiator, heating and stirring, purifying and drying to obtain a modified carbon nanotube; the preparation method comprises the following steps: stirring and mixing an antioxidant and an alkaline solution in a nitrogen atmosphere, slowly adding a nitrate solution, adjusting the pH value, standing, purifying, freeze-drying, and spraying a coupling agent solution for drying to obtain an antioxidant filler; pP, the modified carbon nanotubes, the antioxidant filler and the lubricant are subjected to mixing, melt extrusion and granulation, and the polypropylene composite material is obtained. The filler is used for modification, so that the compatibility, dispersity and binding force of the conductive master batch in a PP system are improved, and the conductive function and mechanical strength of the conductive master batch are improved.

Description

Technical Field

[0001] The invention belongs to the technical field of carbon nanotube conductive masterbatch, and relates to a preparation method and application of the carbon nanotube conductive masterbatch. Background Art

[0002] Conductive materials play a vital role in modern science and technology and industrial production. Polypropylene (PP), as a widely used plastic material, is also widely used in the field of conductive materials due to its excellent chemical stability and good mechanical properties. PP materials can be given conductive properties by adding conductive fillers such as carbon nanotubes, carbon fibers or metal powders.

[0003] Carbon nanotubes are one-dimensional carbon nanomaterials, that is, small tubes with nanometer diameters. They have good electrical conductivity, high thermal conductivity, chemical stability and thermal stability. Due to their low density and large aspect ratio, carbon nanotubes have become a good conductive filler for polymer composite materials.

[0004] Among them, PP itself is relatively brittle, and the bonding ability between carbon nanotubes and PP is poor. Direct mixing will lead to uneven dispersion and affect the conductive properties of the material. Therefore, a specific preparation method is needed to solve this problem in order to improve the dispersion and interfacial bonding of carbon nanotubes in the PP matrix. Summary of the invention

[0005] The purpose of the present invention is to provide a preparation method and application of a carbon nanotube conductive masterbatch. The present invention introduces carbon-carbon double bonds through carbon nanotube modification, participates in the polymerization reaction of styrene and magnolia aldehyde B, combines on the surface of an antioxidant to in-situ generate zinc / aluminum hydrotalcite, and introduces amino groups through a coupling agent so that they can form covalent bonds with active aldehyde groups on the modified carbon nanotubes, thereby increasing the compatibility, dispersibility and bonding force of the filler in a PP system, thereby significantly improving the conductive function and mechanical strength of the conductive masterbatch.

[0006] The purpose of the present invention can be achieved through the following technical solutions:

[0007] A method for preparing a carbon nanotube conductive masterbatch comprises the following steps:

[0008] S1, stirring and mixing a silane coupling agent, a solvent and an organic tin catalyst, spraying the obtained mixed solution on the surface of the carbon nanotubes and then heat-insulating the mixture, filtering out solids, washing with alcohol, and drying in an oven to obtain pretreated carbon nanotubes;

[0009] S2, placing the pretreated carbon nanotubes in anhydrous ethanol for ultrasonic treatment, adding reaction monomers and initiators, heating and stirring, filtering out solids, washing with alcohol, and drying to obtain modified carbon nanotubes;

[0010] S3. In a nitrogen atmosphere, the antioxidant and the alkaline solution are stirred and mixed, and then the nitrate solution is slowly added, and the pH value is adjusted. After standing, the solid is filtered out, washed, freeze-dried, sprayed with a coupling agent solution, and dried to obtain an antioxidant filler;

[0011] S4, mixing PP, modified carbon nanotubes, antioxidant filler and lubricant in an internal mixer, placing them in a twin-screw extruder for melt extrusion, and granulating to obtain the product.

[0012] As a preferred technical solution of the present invention, in step S1, the stirring and mixing time is 10-15 minutes; the heat preservation treatment is heat preservation at 50-60°C for 4-5 hours; and the alcohol washing is washing with anhydrous ethanol for 3 times.

[0013] As a preferred technical solution of the present invention, in step S1, the mass ratio of the silane coupling agent, the solvent, the organic tin catalyst and the carbon nanotubes is 10-12:60-70:0.08-0.10:30-36.

[0014] As a preferred technical solution of the present invention, in step S1, the silane coupling agent is one or both of vinyltrimethoxysilane and vinyltriethoxysilane; the organic tin catalyst is dibutyltin dilaurate; and the solvent is one or more of ethanol, ethyl acetate and butyl acetate.

[0015] As a preferred technical solution of the present invention, in step S2, the ultrasonic treatment is ultrasonic treatment at a power of 300-400W for 8-10min; the heating and stirring is stirring at a temperature of 60-70°C for 6-7h; the alcohol washing is washing with anhydrous ethanol for 4 times; and the drying is drying to constant weight.

[0016] As a preferred technical solution of the present invention, in step S2, the mass ratio of the pretreated carbon nanotubes, anhydrous ethanol, reaction monomer and initiator is 8-10:25-30:1.2-1.4:0.04-0.05; the reaction monomer is a mixture of styrene and magnolia aldehyde B in a mass ratio of 3:1.6-1.8.

[0017] As a preferred technical solution of the present invention, in step S3, the stirring and mixing is stirring at a speed of 120-160r / min for 15-20min; the pH value is adjusted to 9-10; the standing time is 1.5-2.0h; and the washing is washing with deionized water until the solid surface is neutral.

[0018] As a preferred technical solution of the present invention, in step S3, the mass ratio of the antioxidant, alkaline solution, nitrate solution and coupling agent solution is 8.0-8.3:150-160:120-130:9-10; the nitrate solution is formed by mixing zinc nitrate, aluminum nitrate and deionized water in a mass ratio of 10-12:7.8-8.2:100-110; the alkaline solution is formed by mixing sodium hydroxide and deionized water in a dosage ratio of 1g:20mL.

[0019] As a preferred technical solution of the present invention, in step S3, the antioxidant is one or more of antioxidant 168, antioxidant 1010, antioxidant 1076 and antioxidant 1310; the coupling agent solution is formed by mixing silane coupling agent KH550 and anhydrous ethanol in a mass ratio of 1:3.

[0020] As a preferred technical solution of the present invention, in step S4, the mixing is performed for 10-15 minutes; and the temperature of the melt extrusion is 240-250°C.

[0021] As a preferred technical solution of the present invention, in step S4, the mass ratio of the PP, modified carbon nanotubes, antioxidant filler and lubricant is 75-80:11-13:6-7:1.0-1.2; and the lubricant is pentaerythritol stearate.

[0022] The invention discloses application of carbon nanotube conductive masterbatch prepared by the preparation method in conductive PP material.

[0023] Beneficial effects of the present invention:

[0024] The present invention modifies carbon nanotubes by vinyl trimethoxysilane so that the carbon nanotubes can react with styrene and magnolia aldehyde B in a polymerization reaction. The carbon nanotubes are modified by organic copolymerization to introduce a double benzene ring structure and an active group, thereby increasing the interface bonding strength between the carbon nanotubes and PP and improving the dispersibility thereof. At the same time, zinc / aluminum hydrotalcite is in situ generated on the surface of an antioxidant. The zinc / aluminum hydrotalcite is modified by an antioxidant to increase its compatibility in a PP system. An amino group is introduced by a coupling agent so that the amino group can form a covalent bond with an active aldehyde group on the modified carbon nanotube. The organic polymer on the surface of the carbon nanotube has a volume-increasing effect, further improving the dispersibility and bonding strength of the filler in the PP system, thereby significantly improving the conductive function and mechanical strength of the conductive masterbatch. DETAILED DESCRIPTION

[0025] In order to further illustrate the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the specific implementation methods, structures, features and effects of the present invention are described in detail below in combination with the embodiments.

[0026] Example 1

[0027] A method for preparing a carbon nanotube conductive masterbatch comprises the following steps:

[0028] S1. Stir vinyl trimethoxysilane, ethanol and dibutyltin dilaurate for 10 minutes, spray the obtained mixed solution on the surface of carbon nanotubes, and keep it at 50°C for 4 hours, filter out solids, wash them with anhydrous ethanol for 3 times, and dry them in an oven to constant weight to obtain pretreated carbon nanotubes; the mass ratio of the silane coupling agent, solvent, dibutyltin dilaurate and carbon nanotubes is 10:60:0.08:30;

[0029] S2, placing the pretreated carbon nanotubes in anhydrous ethanol and ultrasonically treating at 300W for 8 minutes, adding the reaction monomer and the initiator and stirring at 60°C for 6 hours, filtering the solid, washing it with anhydrous ethanol for 4 times, and drying it to constant weight to obtain modified carbon nanotubes; the mass ratio of the pretreated carbon nanotubes, anhydrous ethanol, the reaction monomer and the initiator is 8:25:1.2:0.04; the reaction monomer is a mixture of styrene and magnolia aldehyde B in a mass ratio of 3:1.6; the initiator is initiator AIBN;

[0030] S3. Under a nitrogen atmosphere, the antioxidant and alkaline solution were stirred at a speed of 120 r / min for 15 min, and then the nitrate solution was slowly added, and the pH value was adjusted to 9. After standing for 1.5 h, the solid was filtered out and washed with deionized water until the solid surface was neutral, freeze-dried, sprayed with coupling agent solution, and then dried at 80°C to constant weight for 40 min to obtain an antioxidant filler; the mass ratio of the antioxidant, alkaline solution, nitrate solution and coupling agent solution was 8.0:150:120:9; the nitrate solution was prepared by mixing zinc nitrate, aluminum nitrate and deionized water in a mass ratio of 10:7.8:100; the alkaline solution was prepared by mixing sodium hydroxide and deionized water in a dosage ratio of 1 g:20 mL; the antioxidant was antioxidant 1010; the coupling agent solution was prepared by mixing silane coupling agent KH550 and anhydrous ethanol in a mass ratio of 1:3;

[0031] S4. Place PP, modified carbon nanotubes, antioxidant filler and lubricant in an internal mixer and mix for 10 minutes, place in a twin-screw extruder and melt-extrude at 240°C, and granulate to obtain; the mass ratio of the PP, modified carbon nanotubes, antioxidant filler and lubricant is 75:11:6:1.0; the lubricant is pentaerythritol stearate.

[0032] Example 2

[0033] A method for preparing a carbon nanotube conductive masterbatch comprises the following steps:

[0034] S1. Stir vinyl trimethoxysilane, ethanol and dibutyltin dilaurate for 12 minutes, spray the obtained mixed solution on the surface of carbon nanotubes, and keep the mixture at 55°C for 4.5 hours, filter out solids, wash them with anhydrous ethanol for 3 times, and dry them in an oven to constant weight to obtain pretreated carbon nanotubes; the mass ratio of the silane coupling agent, solvent, dibutyltin dilaurate and carbon nanotubes is 11:65:0.09:33;

[0035] S2, placing the pretreated carbon nanotubes in anhydrous ethanol and ultrasonically treating at 350W for 9 minutes, adding the reaction monomer and the initiator and stirring at 65°C for 6.5 hours, filtering the solid, washing it with anhydrous ethanol for 4 times, and drying it to constant weight to obtain modified carbon nanotubes; the mass ratio of the pretreated carbon nanotubes, anhydrous ethanol, the reaction monomer and the initiator is 9:28:1.3:0.045; the reaction monomer is a mixture of styrene and magnolia aldehyde B in a mass ratio of 3:1.7; the initiator is initiator AIBN;

[0036] S3. Under a nitrogen atmosphere, the antioxidant and alkaline solution were stirred at a speed of 140 r / min for 18 min, and then the nitrate solution was slowly added, and the pH value was adjusted to 9.5. After standing for 1.8 h, the solid was filtered out and washed with deionized water until the solid surface was neutral, freeze-dried, sprayed with coupling agent solution, and allowed to stand for 40 min. After that, it was dried at 80°C to constant weight to obtain an antioxidant filler; the mass ratio of the antioxidant, alkaline solution, nitrate solution and coupling agent solution was 8.2:155:125:9.5; the nitrate solution was prepared by mixing zinc nitrate, aluminum nitrate and deionized water in a mass ratio of 11:8:105; the alkaline solution was prepared by mixing sodium hydroxide and deionized water in a dosage ratio of 1 g:20 mL; the antioxidant was antioxidant 1010; the coupling agent solution was prepared by mixing silane coupling agent KH550 and anhydrous ethanol in a mass ratio of 1:3;

[0037] S4. Place PP, modified carbon nanotubes, antioxidant filler and lubricant in an internal mixer and mix for 12 minutes, place in a twin-screw extruder and melt-extrude at 245°C, and granulate to obtain the product; the mass ratio of the PP, modified carbon nanotubes, antioxidant filler and lubricant is 78:12:6.5:1.1; the lubricant is pentaerythritol stearate.

[0038] Example 3

[0039] A method for preparing a carbon nanotube conductive masterbatch comprises the following steps:

[0040] S1. Stir vinyl trimethoxysilane, ethanol and dibutyltin dilaurate for 15 minutes, spray the obtained mixed solution on the surface of carbon nanotubes, and keep the mixture at 60°C for 5 hours, filter out the solid, wash it with anhydrous ethanol for 3 times, and dry it in an oven to constant weight to obtain pretreated carbon nanotubes; the mass ratio of the silane coupling agent, solvent, dibutyltin dilaurate and carbon nanotubes is 12:70:0.10:36;

[0041] S2, placing the pretreated carbon nanotubes in anhydrous ethanol and ultrasonically treating at 400W for 10 minutes, adding the reaction monomer and the initiator and stirring at 70°C for 7 hours, filtering the solid, washing it with anhydrous ethanol for 4 times, and drying it to constant weight to obtain modified carbon nanotubes; the mass ratio of the pretreated carbon nanotubes, anhydrous ethanol, the reaction monomer and the initiator is 10:30:1.4:0.05; the reaction monomer is a mixture of styrene and magnolia aldehyde B in a mass ratio of 3:1.8; the initiator is initiator AIBN;

[0042] S3. Under a nitrogen atmosphere, the antioxidant and alkaline solution are stirred at a speed of 160r / min for 20min, and then the nitrate solution is slowly added, and the pH value is adjusted to 10. After standing for 2.0h, the solid is filtered and washed with deionized water until the solid surface is neutral, freeze-dried, sprayed with coupling agent solution, and allowed to stand for 40min, and then dried at 80°C to constant weight to obtain an antioxidant filler; the mass ratio of the antioxidant, alkaline solution, nitrate solution and coupling agent solution is 8.3:160:130:10; the nitrate solution is a mixture of zinc nitrate, aluminum nitrate and deionized water in a mass ratio of 12:8.2:110; the alkaline solution is a mixture of sodium hydroxide and deionized water in a dosage ratio of 1g:20mL; the antioxidant is antioxidant 1010; the coupling agent solution is a mixture of silane coupling agent KH550 and anhydrous ethanol in a mass ratio of 1:3;

[0043] S4. Place PP, modified carbon nanotubes, antioxidant filler and lubricant in an internal mixer and mix them for 15 minutes. Place them in a twin-screw extruder and melt-extrude them at 250°C, and then granulate them to obtain the product. The mass ratio of the PP, modified carbon nanotubes, antioxidant filler and lubricant is 80:13:7:1.2. The lubricant is pentaerythritol stearate.

[0044] Comparative Example 1

[0045] Compared with Example 3, Comparative Example 1 is different in that vinyltrimethoxysilane is not used, and the other components, preparation steps and parameters are the same.

[0046] Comparative Example 2

[0047] Compared with Example 3, the difference in Comparative Example 2 is that styrene is used instead of magnolia aldehyde B, and the other components, preparation steps and parameters are the same.

[0048] Comparative Example 3

[0049] Compared with Example 3, the difference in Comparative Example 3 is that magnolol is used instead of magnolaldehyde B, and the other components, preparation steps and parameters are the same.

[0050] Comparative Example 4

[0051] Compared with Example 3, Comparative Example 4 is different in that step S3;

[0052] Step S3: Under a nitrogen atmosphere, the alkaline solution was stirred at a speed of 160 r / min for 20 min, and then the nitrate solution was slowly added, and the pH value was adjusted to 10. After standing for 2.0 h, the solid was filtered out, washed with deionized water until the solid surface was neutral, an antioxidant was added and mixed, and then freeze-dried, sprayed with a coupling agent solution, and then stood for 40 min and dried at 80° C. to constant weight to obtain an antioxidant filler;

[0053] The remaining components, preparation steps and parameters were the same.

[0054] Comparative Example 5

[0055] Compared with Example 3, the difference in Comparative Example 5 is that no coupling agent is used in step S3, and the other components, preparation steps and parameters are the same.

[0056] The conductive masterbatches prepared in Examples 1-3 and Comparative Examples 1-5 were tested for the following properties, respectively. The test results are shown in Table 1.

[0057] Surface resistance test: according to GB / T1410-2006;

[0058] Tensile performance test: according to GB / T1040.1-2018;

[0059] Table 1

[0060] Surface resistance (Ω*cm) Tensile strength(MPa) Example 1 <![CDATA[3.3*10 4 ]]> 32.4 Example 2 <![CDATA[3.5*10 4 ]]> 32.8 Example 3 <![CDATA[3.2*10 4 ]]> 32.2 Comparative Example 1 <![CDATA[5.6*10 6 ]]> 22.2 Comparative Example 2 <![CDATA[8.2*10 5 ]]> 24.4 Comparative Example 3 <![CDATA[4.4*10 5 ]]> 25.6 Comparative Example 4 <![CDATA[6.3*10 7 ]]> 21.4 Comparative Example 5 <![CDATA[5.4*10 5 ]]> 24.8

[0061] From the test results in Table 1, it can be seen that compared with Comparative Examples 1-5, the conductive masterbatch prepared in Examples 1-3 has excellent conductive function and mechanical strength.

[0062] The present invention modifies carbon nanotubes by vinyl trimethoxysilane so that the carbon nanotubes can react with styrene and magnolia aldehyde B in a polymerization reaction. The carbon nanotubes are modified by organic copolymerization to introduce a double benzene ring structure and an active group, thereby increasing the interface bonding strength between the carbon nanotubes and PP and improving the dispersibility thereof. At the same time, zinc / aluminum hydrotalcite is in situ generated on the surface of an antioxidant. The zinc / aluminum hydrotalcite is modified by an antioxidant to increase its compatibility in a PP system. An amino group is introduced by a coupling agent so that the amino group can form a covalent bond with an active aldehyde group on the modified carbon nanotube. The organic polymer on the surface of the carbon nanotube has a volume-increasing effect, further improving the dispersibility and bonding strength of the filler in the PP system, thereby significantly improving the conductive function and mechanical strength of the conductive masterbatch.

[0063] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technical personnel in this field can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any indirect modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A method for preparing carbon nanotube conductive masterbatch, characterized in that: The preparation method comprises the following steps: S1, stirring and mixing a silane coupling agent, a solvent and an organic tin catalyst, spraying the obtained mixed solution on the surface of the carbon nanotubes and then heat-insulating the mixture, filtering out solids, washing with alcohol, and drying in an oven to obtain pretreated carbon nanotubes; S2, placing the pretreated carbon nanotubes in anhydrous ethanol for ultrasonic treatment, adding reaction monomers and initiators, heating and stirring, filtering out solids, washing with alcohol, and drying to obtain modified carbon nanotubes; S3. In a nitrogen atmosphere, the antioxidant and the alkaline solution are stirred and mixed, and then the nitrate solution is slowly added, and the pH value is adjusted. After standing, the solid is filtered out, washed, freeze-dried, sprayed with a coupling agent solution, and dried to obtain an antioxidant filler; S4, mixing PP, modified carbon nanotubes, antioxidant filler and lubricant in an internal mixer, placing them in a twin-screw extruder for melt extrusion, and granulating to obtain the product.

2. The method for preparing a carbon nanotube conductive masterbatch according to claim 1, characterized in that: In step S1, the stirring and mixing time is 10-15 minutes; the heat preservation treatment is heat preservation at 50-60°C for 4-5 hours; and the alcohol washing is washing with anhydrous ethanol for 3 times.

3. The method for preparing a carbon nanotube conductive masterbatch according to claim 1, characterized in that: In step S1, the mass ratio of the silane coupling agent, the solvent, the organic tin catalyst and the carbon nanotubes is 10-12:60-70:0.08-0.10:30-36; the silane coupling agent is one or two of vinyl trimethoxy silane and vinyl triethoxy silane; the organic tin catalyst is dibutyl tin dilaurate; and the solvent is one or more of ethanol, ethyl acetate and butyl acetate.

4. The method for preparing a carbon nanotube conductive masterbatch according to claim 1, characterized in that: In step S2, the ultrasonic treatment is performed at a power of 300-400 W for 8-10 min; the heating and stirring is performed at a temperature of 60-70° C. for 6-7 h; the alcohol washing is performed 4 times with anhydrous ethanol; and the drying is performed to a constant weight.

5. The method for preparing a carbon nanotube conductive masterbatch according to claim 1, characterized in that: In step S2, the mass ratio of the pretreated carbon nanotubes, anhydrous ethanol, reaction monomer and initiator is 8-10:25-30:1.2-1.4:0.04-0.05; the reaction monomer is prepared by mixing styrene and magnolia aldehyde B in a mass ratio of 3:1.6-1.

8.

6. The method for preparing a carbon nanotube conductive masterbatch according to claim 1, characterized in that: In step S3, the stirring and mixing is stirring at a speed of 120-160 r / min for 15-20 min; the pH value is adjusted to 9-10; the standing time is 1.5-2.0 h; and the washing is washing with deionized water until the solid surface is neutral.

7. The method for preparing a carbon nanotube conductive masterbatch according to claim 1, characterized in that: In step S3, the mass ratio of the antioxidant, alkaline solution, nitrate solution and coupling agent solution is 8.0-8.3:150-160:120-130:9-10; the nitrate solution is formed by mixing zinc nitrate, aluminum nitrate and deionized water in a mass ratio of 10-12:7.8-8.2:100-110; the alkaline solution is formed by mixing sodium hydroxide and deionized water in a dosage ratio of 1g:20mL; the antioxidant is one or more of antioxidant 168, antioxidant 1010, antioxidant 1076 and antioxidant 1310; the coupling agent solution is formed by mixing silane coupling agent KH550 and anhydrous ethanol in a mass ratio of 1:

3.

8. The method for preparing a carbon nanotube conductive masterbatch according to claim 1, characterized in that: In step S4, the mixing is performed for 10-15 minutes; and the temperature of the melt extrusion is 240-250°C.

9. The method for preparing a carbon nanotube conductive masterbatch according to claim 1, characterized in that: In step S4, the mass ratio of the PP, modified carbon nanotubes, antioxidant filler and lubricant is 75-80:11-13:6-7:1.0-1.2; and the lubricant is pentaerythritol stearate.

10. Use of the carbon nanotube conductive masterbatch prepared by the preparation method according to any one of claims 1 to 9 in conductive PP materials.