Conductive PE material with good shock resistance and low resistance and preparation method thereof

Abstract

The application relates to the technical field of polyethylene, and discloses a conductive PE material with good shock resistance and low resistance and a preparation method thereof; the conductive PE material comprises 100 parts by weight of polyethylene resin, 10-35 parts by weight of SBS elastomer, 1.2-5 parts by weight of triethanolamine quaternary ammonium salt styrene grafted polyethylene and 1-6 parts by weight of carboxylated carbon nanotubes; the triethanolamine quaternary ammonium salt styrene grafted polyethylene plays a role of a compatibilizer, improves the compatibility among the carboxylated carbon nanotubes, the SBS elastomer and the polyethylene resin, and is favorable for improving the toughness, impact resistance, bending resistance, shock resistance and mechanical properties of the polyethylene resin; the carbon nanotubes are uniformly dispersed in the material matrix to form a continuous conductive network, which is favorable for reducing the resistance and the conductive property of the PE material, and improving the conductive property and the antistatic property.

Description

Technical Field

[0001] This invention relates to the field of polyethylene technology, specifically to a conductive PE material with good shock resistance and low resistance, and its preparation method. Background Technology

[0002] Polyethylene resin is odorless, non-toxic, has good low-temperature resistance, and is low in cost. It is widely used in films, packaging, containers, pipes, wires and cables, etc. Improving the impact resistance, bending resistance, shock resistance, conductivity, and antistatic properties of polyethylene materials is of great significance. SBS elastomer, a triblock copolymer composed of styrene and butadiene, is a high-performance thermoplastic elastomer that can improve the mechanical properties of polymer materials such as polyethylene, asphalt, epoxy resin, and polyurethane.

[0003] Adding inorganic nanomaterials such as carbon nanotubes, nano-silica, and nano-zinc oxide to polyethylene can improve its mechanical strength and antistatic properties. Chinese patent CN114213744B discloses an antistatic packaging material using polyvinyl alcohol-modified multi-walled carbon nanotubes as an antistatic agent, which exhibits good compatibility with linear low-density polyethylene, thus enhancing the mechanical and antistatic properties of the packaging material. Compared to the invention patent, this invention not only reduces the surface resistance of polyethylene material and improves its antistatic / conductive properties, but also utilizes SBS elastomers to improve the flexural strength and impact resistance of polyethylene resin. Summary of the Invention

[0004] This invention solves the problems of poor impact resistance, electrical conductivity, and antistatic properties of polyethylene materials.

[0005] The technical solution adopted in this invention is: a conductive PE material with good shock resistance and low resistance, comprising 100 parts by weight of polyethylene resin, 10-35 parts by weight of SBS elastomer, 1.2-5 parts by weight of triethanolamine quaternary ammonium salt styrene-grafted polyethylene, 1-6 parts by weight of carboxylated carbon nanotubes, and 0.3-0.5 parts by weight of antioxidant.

[0006] Furthermore, the preparation method of the conductive PE material with good shock resistance and low resistance is as follows: polyethylene resin, SBS elastomer, triethanolamine quaternary ammonium salt styrene-grafted polyethylene, carboxylated carbon nanotubes, and antioxidant are mixed in a mixer, and then melt-mixed, extruded, and pelletized in a twin-screw extruder to obtain the conductive PE material with good shock resistance and low resistance.

[0007] Furthermore, the mixing temperature of the mixer is 60-70℃ and the mixing time is 20-40 min; the melt blending temperature of the twin-screw extruder is 180-190℃ and the screw speed is 60-100 r / min.

[0008] Furthermore, the preparation method of triethanolamine quaternary ammonium salt styrene-grafted polyethylene is as follows: polyethylene resin, 4-vinylbenzyltriethanolamine quaternary ammonium salt, and dicumyl peroxide in a mass ratio of 100:(4-15):(0.2-0.8) are added to a twin-screw extruder, and the mixture is melt-grafted at 175-185℃ for 4-8 min. The product is discharged, and the product is added to xylene, heated to 140℃ and refluxed, and stirred for 4-6 h until dissolved. Then, acetone is added for precipitation. The precipitate is extracted with acetone in a Soxhlet extractor and dried to obtain triethanolamine quaternary ammonium salt styrene-grafted polyethylene.

[0009] Furthermore, the preparation method of 4-vinylbenzyltriethanolamine quaternary ammonium salt is as follows: 4-chloromethylstyrene and triethanolamine are added to acetonitrile in a molar ratio of 1:(1-1.05). The mixture is heated to 40-55℃ under a nitrogen atmosphere and reacted for 18-30 h. The mixture is then concentrated under reduced pressure, and the product is recrystallized from a mixed solution of ethanol and ethyl acetate to obtain 4-vinylbenzyltriethanolamine quaternary ammonium salt. The reaction formula is:

[0010]

[0011] Furthermore, the preparation method of carboxylated carbon nanotubes is as follows: carbon nanotubes are added to a nitric acid solution with a mass fraction of 60-68%, ultrasonically dispersed, heated to 50-60℃, reacted for 1-2 hours, cooled and filtered, the product is added to a sodium hydroxide solution, stirred and filtered, washed with water and dried to obtain carboxylated carbon nanotubes.

[0012] The technical effects of this invention are as follows: 4-Ethylbenzyltriethanolamine quaternary ammonium salt is used to melt-graft modify polyethylene resin, resulting in quaternary ammonium salt styrene-grafted polyethylene. This polyethylene is then melt-extruded with polyethylene resin and SBS elastomer to obtain a conductive PE material with good shock resistance and low electrical resistance. The quaternary ammonium salt styrene-grafted polyethylene contains a polyethylene backbone with side-linked polystyrene molecular chains. Its polyethylene backbone has excellent compatibility with polyethylene resin, and the polystyrene molecular chains also have similar polarity to the styrene block molecular chains in the SBS elastomer. This allows the quaternary ammonium salt styrene-grafted polyethylene to act as a compatibilizer, further improving the compatibility between the SBS elastomer and polyethylene resin. This results in a good toughening effect from the SBS elastomer, which is beneficial for improving the toughness and mechanical properties of the polyethylene resin.

[0013] The quaternary ammonium salt styrene-grafted polyethylene of the present invention contains quaternary ammonium salt cationic groups, which can interact with the sodium carboxylate anions on the surface of carboxylated carbon nanotubes through anionic-cationic bond interactions. This allows the quaternary ammonium salt styrene-grafted polyethylene to modify the surface of carbon nanotubes, improving the dispersibility of carbon nanotubes, enhancing the compatibility between carbon nanotubes and SBS elastomers and polyethylene resins, enabling carbon nanotubes to play a good reinforcing role, and further improving the flexural strength and impact strength of PE materials.

[0014] The carboxylated carbon nanotubes of this invention, modified by quaternary ammonium salt styrene-grafted polyethylene, are uniformly dispersed in the material matrix to form a continuous conductive network. This is beneficial for reducing the resistance and conductivity of the PE material. At the same time, the quaternary ammonium salt styrene-grafted polyethylene contains quaternary ammonium salt and polyhydroxy hydrophilic groups, which improves the surface hydrophilicity of the PE material. It can absorb moisture from the air and form a conductive layer, which is beneficial for reducing surface resistance and preventing static electricity accumulation, thereby improving conductivity and antistatic properties. Detailed Implementation

[0015] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the embodiments of this application. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0016] The polyethylene resin used in the specific embodiments and examples is DMDA-8920, manufactured by Shanghai Handar New Materials Co., Ltd. The SBS elastomer is YH-1401, manufactured by Dongguan Lingxing Plastic Raw Materials Co., Ltd. The carbon nanotubes, with a length specification of 0.5-2µm, are from Zhongke Leiming (Beijing) Technology Co., Ltd.

[0017] Example 1:

[0018] (1) Add 0.5g of carbon nanotubes to 250mL of 68% nitric acid solution, disperse by ultrasonication, heat to 50℃, react for 2h, cool and filter, add the product to 10% sodium hydroxide solution, stir for 30min and filter, wash with water and dry to obtain carboxylated carbon nanotubes.

[0019] (2) Add 20 mmol of 4-chloromethylstyrene and 20 mmol of triethanolamine to 20 mL of acetonitrile, heat to 40 °C in a nitrogen atmosphere, react for 30 h, concentrate under reduced pressure, and recrystallize the product in a mixed solution of ethanol and ethyl acetate to obtain 4-vinylbenzyltriethanolamine quaternary ammonium salt.

[0020] (3) Add 50g of polyethylene resin, 2g of 4-vinylbenzyltriethanolamine quaternary ammonium salt and 0.1g of dicumyl peroxide to a twin-screw extruder, melt-graft at 180℃ for 4min, discharge the product, add the product to xylene, heat to 140℃ and reflux, stir for 4h until dissolved, then add acetone to precipitate, extract the precipitate with acetone in a Soxhlet extractor, dry it to obtain triethanolamine quaternary ammonium salt styrene-grafted polyethylene.

[0021] (4) Mix 1 kg of polyethylene resin, 100 g of SBS elastomer, 12 g of triethanolamine quaternary ammonium salt styrene-grafted polyethylene, 10 g of carboxylated carbon nanotubes and 3 g of antioxidant 1010 in a mixer at 60 °C for 40 min. Then melt mix in a twin-screw extruder at a controlled temperature of 180 °C and a screw speed of 100 r / min. Extrude and pelletize to obtain a conductive PE material with good shock resistance and low resistance.

[0022] Comparative Example 1:

[0023] (1) Mix 1 kg of polyethylene resin, 100 g of SBS elastomer and 3 g of antioxidant 1010 in a mixer at 60°C for 40 min, then melt mix in a twin-screw extruder at a controlled temperature of 180°C and a screw speed of 100 r / min, extrude and pelletize to obtain PE material.

[0024] Comparative Example 2:

[0025] (1) 1 kg of polyethylene resin, 100 g of SBS elastomer, 12 g of triethanolamine quaternary ammonium salt styrene-grafted polyethylene (prepared according to the method of Example 1) and 3 g of antioxidant 1010 were mixed in a mixer at 60°C for 40 min. Then, they were melt-mixed in a twin-screw extruder at a controlled temperature of 180°C and a screw speed of 100 r / min. The mixture was then extruded and pelletized to obtain PE material.

[0026] Comparative Example 3:

[0027] (1) 1 kg of polyethylene resin, 100 g of SBS elastomer, 10 g of carboxylated carbon nanotubes (prepared according to the method of Example 1) and 3 g of antioxidant 1010 were mixed in a mixer at 60°C for 40 min. Then, they were melt-mixed in a twin-screw extruder at a controlled temperature of 180°C and a screw speed of 100 r / min. The mixture was then extruded and pelletized to obtain a conductive PE material with good shock resistance and low resistance.

[0028] Comparative Example 4:

[0029] (1) Add 50g polyethylene resin, 2g styrene and 0.1g dicumyl peroxide to a twin-screw extruder, melt graft at 180℃ for 4min, discharge the product, add the product to xylene, heat to 140℃ and reflux, stir for 4h until dissolved, then add acetone to precipitate, extract the precipitate with acetone in a Soxhlet extractor, dry to obtain styrene-grafted polyethylene.

[0030] (2) 1 kg of polyethylene resin, 100 g of SBS elastomer, 12 g of styrene-grafted polyethylene, 10 g of carboxylated carbon nanotubes (prepared according to the method of Example 1) and 3 g of antioxidant 1010 were mixed in a mixer at 60°C for 40 min. Then, the mixture was melt-mixed in a twin-screw extruder at a controlled temperature of 180°C and a screw speed of 100 r / min. The mixture was then extruded and pelletized to obtain a conductive PE material with good shock resistance and low resistance.

[0031] Comparative Example 5:

[0032] (1) 1 kg of polyethylene resin, 100 g of SBS elastomer, 12 g of triethanolamine quaternary ammonium salt styrene-grafted polyethylene (prepared according to the method of Example 1), 10 g of carbon nanotubes, and 3 g of antioxidant 1010 were mixed in a mixer at 60°C for 40 min. Then, the mixture was melt-mixed in a twin-screw extruder at a controlled temperature of 180°C and a screw speed of 100 r / min. The mixture was then extruded and pelletized to obtain a conductive PE material with good shock resistance and low resistance.

[0033] Comparative Example 6:

[0034] (1) Mix 50g of polyethylene resin and 2g of N-triethyl-(4-vinylbenzyl)ammonium chloride (CAS No. 14350-43-7, structural formula: 0.1 g of dicumyl peroxide was added to a twin-screw extruder and melt-grafted at 180°C for 4 min. The product was discharged and added to xylene, heated to 140°C and refluxed, and stirred for 4 h until dissolved. Then acetone was added to precipitate the product. The precipitate was extracted with acetone in a Soxhlet extractor and dried to obtain quaternary ammonium salt styrene-grafted polyethylene.

[0035] (2) 1 kg of polyethylene resin, 100 g of SBS elastomer, 12 g of quaternary ammonium salt styrene-grafted polyethylene, 10 g of carboxylated carbon nanotubes (prepared according to the method of Example 1) and 3 g of antioxidant 1010 were mixed in a mixer at 60°C for 40 min. Then, the mixture was melt-mixed in a twin-screw extruder at a controlled temperature of 180°C and a screw speed of 100 r / min. The mixture was then extruded and pelletized to obtain a conductive PE material with good shock resistance and low resistance.

[0036] Example 2:

[0037] (1) Add 0.5g of carbon nanotubes to 300mL of 60% nitric acid solution, disperse by ultrasonication, heat to 60℃, react for 1h, cool and filter, add the product to 10% sodium hydroxide solution, stir for 30min and filter, wash with water and dry to obtain carboxylated carbon nanotubes.

[0038] (2) Add 20 mmol of 4-chloromethylstyrene and 21 mmol of triethanolamine to 20 mL of acetonitrile, heat to 55 °C in a nitrogen atmosphere, react for 18 h, concentrate under reduced pressure, and recrystallize the product in a mixed solution of ethanol and ethyl acetate to obtain 4-vinylbenzyltriethanolamine quaternary ammonium salt.

[0039] (3) Add 50g of polyethylene resin, 4.8g of 4-vinylbenzyltriethanolamine quaternary ammonium salt and 0.25g of dicumyl peroxide to a twin-screw extruder, melt-graft at 175℃ for 8min, discharge the product, add the product to xylene, heat to 140℃ and reflux, stir for 6h until dissolved, then add acetone to precipitate, extract the precipitate with acetone in a Soxhlet extractor, dry it to obtain triethanolamine quaternary ammonium salt styrene-grafted polyethylene.

[0040] (4) Mix 1 kg of polyethylene resin, 220 g of SBS elastomer, 30 g of triethanolamine quaternary ammonium salt styrene-grafted polyethylene, 30 g of carboxylated carbon nanotubes and 5 g of antioxidant 1010 in a mixer at 70°C for 40 min. Then melt mix in a twin-screw extruder at a controlled temperature of 190°C and a screw speed of 100 r / min. Extrude and pelletize to obtain a conductive PE material with good shock resistance and low resistance.

[0041] Example 3:

[0042] (1) 50g of polyethylene resin, 7.5g of 4-vinylbenzyltriethanolamine quaternary ammonium salt (prepared according to the method of Example 1) and 0.4g of dicumyl peroxide were added to a twin-screw extruder and melt-grafted at 185°C for 5 min. The product was discharged and added to xylene, heated to 140°C and refluxed, and stirred for 4 h until dissolved. Then acetone was added for precipitation. The precipitate was extracted with acetone in a Soxhlet extractor and dried to obtain triethanolamine quaternary ammonium salt styrene-grafted polyethylene.

[0043] (2) 1 kg of polyethylene resin, 350 g of SBS elastomer, 50 g of triethanolamine quaternary ammonium salt styrene-grafted polyethylene, 60 g of carboxylated carbon nanotubes (prepared according to the method of Example 1) and 4 g of antioxidant 1010 were mixed in a mixer at 60°C for 40 min. Then, the mixture was melt-mixed in a twin-screw extruder at a controlled temperature of 185°C and a screw speed of 60 r / min. The mixture was then extruded and pelletized to obtain a conductive PE material with good shock resistance and low resistance.

[0044] PE material was injection molded into standard specimens using an injection molding machine. Bending performance was tested according to national standard GB / T 9341-2008. Impact performance was tested according to national standard GB / T 1043.1-2008.

[0045] The surface resistivity of PE material was tested according to GB / T 1410-2006. The test temperature was 25℃.

[0046] Table 1

[0047]

[0048]

[0049] As shown in the table above, the PE material in Example 1 exhibits high flexural strength and impact strength, along with better toughness, impact resistance, and flexural and seismic performance. This is mainly due to the addition of SBS elastomer, quaternary ammonium styrene-grafted polyethylene, and carboxylated carbon nanotubes. The quaternary ammonium styrene-grafted polyethylene contains a polyethylene backbone with polystyrene molecular chains grafted onto its side links. The polyethylene backbone has excellent compatibility with polyethylene resin, while the polystyrene molecular chains share similar polarity with the styrene block molecular chains in the SBS elastomer. Consequently, the quaternary ammonium styrene-grafted polyethylene acts as a compatibilizer, further improving the compatibility between the SBS elastomer and the polyethylene resin. The compatibility between ethylene resins allows SBS elastomers to provide excellent toughening effects, which is beneficial for improving the toughness and mechanical properties of polyethylene resin. Furthermore, quaternary ammonium salt-grafted polyethylene contains quaternary ammonium salt cationic groups, which can interact with the sodium carboxylate anions on the surface of carboxylated carbon nanotubes through cation-anion bonding. This allows the quaternary ammonium salt-grafted polyethylene to modify the surface of carbon nanotubes, improving the dispersion of carbon nanotubes and enhancing the compatibility between carbon nanotubes and SBS elastomers and polyethylene resins. This allows the carbon nanotubes to play a significant reinforcing role, further improving the flexural strength and impact strength of PE materials. Moreover, the uniform dispersion of carbon nanotubes in the material matrix forms a continuous conductive network, which helps reduce the resistance and conductivity of PE materials. Simultaneously, the quaternary ammonium salt-grafted polyethylene contains quaternary ammonium salts and polyhydroxy hydrophilic groups, increasing the surface hydrophilicity of PE materials. This allows it to absorb moisture from the air, forming a conductive layer, which helps reduce surface resistance, prevents static electricity accumulation, and thus improves conductivity and antistatic properties.

[0050] Comparative Example 1 did not include quaternary ammonium salt styrene-grafted polyethylene and carboxylated carbon nanotubes, thus failing to improve the compatibility between polyethylene resin and SBS elastomer. Furthermore, the PE material exhibited high surface resistance and poor antistatic and electrical conductivity.

[0051] Comparative Example 2 incorporated triethanolamine quaternary ammonium salt styrene-grafted polyethylene, which improved the compatibility between polyethylene resin and SBS elastomer. The flexural strength and impact strength of the PE material were significantly improved, and the surface resistance decreased. This was mainly because the triethanolamine quaternary ammonium salt styrene-grafted polyethylene contains quaternary ammonium salt and polyhydroxy hydrophilic groups, which can improve the surface hydrophilicity of the PE material, absorb moisture from the air, and form a conductive layer, thus helping to reduce the surface resistance, which was lower than that of Comparative Example 1.

[0052] Comparative Example 3 did not add quaternary ammonium salt styrene-grafted polyethylene, which did not improve the compatibility between carboxylated carbon nanotubes, polyethylene resin and SBS elastomer. As a result, the PE material had lower flexural strength and impact strength, and its surface resistivity was higher than that of Example 1, and its antistatic and electrical properties were poor.

[0053] Comparative Example 4 utilizes styrene to melt-graft polyethylene, introducing polystyrene molecular chains into the side chains of polyethylene. This can act as a compatibilizer, improving the compatibility between SBS elastomer and polyethylene resin, which is beneficial for improving the mechanical properties of PE materials. However, styrene-grafted polyethylene does not contain quaternary ammonium salt cations and cannot interact with carboxylated carbon nanotubes. Therefore, it does not improve the compatibility between carbon nanotubes and SBS elastomer and polyethylene resin, resulting in a lower reinforcing effect of carbon nanotubes. The flexural strength and impact strength of the PE material are lower than those of Example 1. Furthermore, styrene-grafted polyethylene does not contain quaternary ammonium salts and polyhydroxy hydrophilic groups, and it does not effectively reduce the surface resistance of the material. The surface resistance is greater than that of Example 1.

[0054] The carbon nanotubes added in Comparative Example 5 do not contain sodium carboxylate anions on their surface, and therefore cannot interact with the quaternary ammonium salt cations of triethanolamine quaternary ammonium salt styrene-grafted polyethylene. This does not improve the compatibility between carbon nanotubes and SBS elastomer and polyethylene resin, resulting in a lower reinforcing effect of carbon nanotubes, and lower flexural strength and impact strength than in Example 1. Furthermore, the carbon nanotubes are poorly dispersed in the PE material matrix and do not form a good continuous conductive path, resulting in a higher surface resistance than in Example 1.

[0055] Comparative Example 6 uses N-triethyl-(4-vinylbenzyl)ammonium chloride to graft and modify polyethylene resin. Since it does not contain polyhydroxyl hydrophilic groups, the surface resistance of the PE material is slightly higher than that of Example 1.

Claims

1. A conductive PE material with good shock resistance and low electrical resistance, characterized in that, The conductive PE material comprises 100 parts by weight of polyethylene resin, 10-35 parts by weight of SBS elastomer, 1.2-5 parts by weight of triethanolamine quaternary ammonium salt styrene-grafted polyethylene, 1-6 parts by weight of carboxylated carbon nanotubes, and 0.3-0.5 parts by weight of antioxidant. The preparation method of the triethanolamine quaternary ammonium salt styrene-grafted polyethylene is as follows: polyethylene resin, 4-vinylbenzyltriethanolamine quaternary ammonium salt, and dicumyl peroxide are added to a twin-screw extruder for melt grafting, and the product is discharged. The product is added to xylene, heated to reflux, stirred and dissolved, and then acetone is added for precipitation. The precipitate is extracted with acetone in a Soxhlet extractor and dried to obtain triethanolamine quaternary ammonium salt styrene-grafted polyethylene.

2. The conductive PE material with good shock resistance and low resistance according to claim 1, characterized in that, The mass ratio of the polyethylene resin, styrene-triethanolamine quaternary ammonium salt, and dicumyl peroxide is 100:(4-15):(0.2-0.8).

3. The conductive PE material with good shock resistance and low resistance according to claim 1, characterized in that, The temperature for the fusion grafting is 175-185℃, and the time is 4-8 minutes.

4. The conductive PE material with good shock resistance and low resistance according to claim 1, characterized in that, The preparation method of the 4-vinylbenzyltriethanolamine quaternary ammonium salt is as follows: 4-chloromethylstyrene and triethanolamine are added to acetonitrile, heated to 40-55℃ in a nitrogen atmosphere, reacted for 18-30 h, concentrated under reduced pressure, and the product is recrystallized from a mixed solution of ethanol and ethyl acetate to obtain the 4-vinylbenzyltriethanolamine quaternary ammonium salt.

5. The conductive PE material with good shock resistance and low resistance according to claim 4, characterized in that, The molar ratio of 4-chloromethylstyrene to triethanolamine is 1:(1-1.05).

6. The conductive PE material with good shock resistance and low resistance according to claim 1, characterized in that, The method for preparing the carboxylated carbon nanotubes is as follows: carbon nanotubes are added to a nitric acid solution, ultrasonically dispersed, heated to 50-60℃, reacted for 1-2 hours, cooled and filtered, the product is added to a sodium hydroxide solution, stirred and filtered, washed with water and dried to obtain carboxylated carbon nanotubes.

7. The conductive PE material with good shock resistance and low resistance according to claim 6, characterized in that, The nitric acid solution has a mass fraction of 60-68%.

8. A method for preparing a conductive PE material with good shock resistance and low resistance as described in any one of claims 1-7, characterized in that, The preparation method is as follows: polyethylene resin, SBS elastomer, triethanolamine quaternary ammonium salt styrene-grafted polyethylene, carboxylated carbon nanotubes, and antioxidants are mixed in a mixer, and then melt-mixed, extruded, and pelletized in a twin-screw extruder to obtain a conductive PE material with good shock resistance and low resistance.

9. The method for preparing the shock-resistant, low-resistance conductive PE material according to claim 8, characterized in that, The mixing temperature in the mixer is 60-70℃ and the mixing time is 20-40 min; the melt mixing temperature of the twin-screw extruder is 180-190℃ and the screw speed is 60-100 r / min.

Images