Preparation method of wear-resistant modified nylon plastic

Abstract

The present invention relates to the technical field of nylon, and discloses a preparation method of wear-resistant modified nylon plastic. Acylated carbon nanotubes and diphenylsulfone-based nylon are reacted, and then melt-blended with nylon 6 resin in an extruder and extruded to obtain wear-resistant modified nylon plastic. During the reaction of the diphenylsulfone-based nylon of the present invention, its active imino group reacts with the acyl chloride groups on the surface of the carbon nanotubes, thereby introducing nylon 6 molecular chains on the surface of the carbon nanotubes, enabling the diphenylsulfone-based nylon to act as a compatibilizer, improving the compatibility between the carbon nanotubes and the nylon 6 resin. The carbon nanotubes are uniformly dispersed in the nylon 6 resin plastic, having a better reinforcing effect, significantly improving the tensile strength, elongation at break and flexural strength of the nylon plastic, and reducing the mass wear amount of the nylon plastic, improving the wear resistance. At the same time, the uniformly dispersed carbon nanotubes can improve the thermal stability of the nylon plastic.

Description

Technical Field

[0001] The present invention relates to the technical field of nylon, and specifically relates to a preparation method of wear-resistant modified nylon plastic. Background Art

[0002] Nylon 6 is a general engineering plastic with excellent properties and is widely used in fields such as automotive parts, electronic appliances, and precision equipment instruments. It is of great significance to improve the mechanical strength, wear resistance, heat resistance and other properties of nylon 6 materials. Filling and modifying nylon 6 with inorganic nano-fillers is a research hotspot. Among them, carbon nanotubes are a kind of one-dimensional quantum nano-materials with special structures, having high mechanical strength, strong high-temperature resistance, good wear resistance, and high thermal conductivity, and are widely used in materials such as nylon.

[0003] Ordinary carbon nanotubes have problems such as poor dispersibility and poor compatibility with nylon 6 resin. The patent with the publication number CN101746747B discloses that multi-walled carbon nanotubes, styrene and maleic anhydride are subjected to a free radical polymerization reaction to obtain styrene maleic anhydride grafted multi-walled carbon nanotubes, and then added to caprolactam monomers to obtain nylon 6 grafted modified carbon nanotubes, which improves the dispersibility of carbon nanotubes and at the same time improves the dispersibility of carbon nanotubes in various polyamides. However, this patent does not improve the wear resistance, heat resistance, mechanical strength and other properties of nylon 6 materials. Summary of the Invention

[0004] (1) The present invention solves the problems of poor wear resistance and low mechanical properties of nylon plastics.

[0005] (2) Technical solution: The preparation method of the wear-resistant modified nylon plastic is the following steps:

[0006] Step A: Press the cleaned nylon 6 resin into a film, add it to ethanol, then add an initiator and a graft monomer with the structural formula , heat to 70 - 80 °C, stir for grafting reaction for 1 - 2.5 h, carry out condensation reflux during the reaction, add acetone, filter and then wash with water, extract the product with acetone in a Soxhlet extractor, and dry to obtain diphenylsulfone-based nylon.

[0007] Step B: Add acyl chloride carbon nanotubes to toluene, stir and then add diphenylsulfone-based nylon and triethylamine, heat to 40 - 75 °C, stir and react for 12 - 24 h, carry out reduced pressure concentration, wash with water, and after drying, melt and blend the product with nylon 6 resin and an antioxidant in an extruder. The temperatures of the first to sixth sections are 230 °C, 240 °C, 260 °C, 270 °C, 270 °C, 265 °C, the screw speed is 100 - 200 r / min, extrude, cool and pelletize to obtain the wear-resistant modified nylon plastic.

[0008] Preferably, in step A, the mass concentration of the initiator in the solution is 150 - 300 g / L, and the concentration of the graft monomer is 0.4 - 1.2 g / L. The initiator is benzoyl peroxide or azobisisobutyronitrile.

[0009] Preferably, in step B, the masses of the carbon nanotube acyl chloride, diphenylsulfone-based nylon, and triethylamine are 0.5 - 6%, 5 - 30%, and 0.02 - 0.3% of the mass of the nylon 6 resin, respectively.

[0010] Preferably, the preparation method of the graft monomer is as follows:

[0011] Step (1): Add 4-bromomethylbenzyl alcohol, acrylic acid, 4-dimethylaminopyridine, and N,N'-dicyclohexylcarbodiimide with a molar ratio of 1:(1 - 1.1):(0.16 - 0.22):(1.1 - 1.2) to dichloromethane, and stir and react at 20 - 30°C for 4 - 7 h. Concentrate under reduced pressure and separate by silica gel column chromatography. The eluent is an ethyl acetate and petroleum ether solution to obtain an intermediate.

[0012] Step (2): Add the intermediate, 4-(phenylsulfonyl)aniline, and 2,6-dimethylpyridine with a molar ratio of 1:(1.2 - 1.3):(1 - 1.2) to N,N-dimethylacetamide. Under a nitrogen atmosphere, stir and react at 50 - 60°C for 12 - 18 h. Concentrate under reduced pressure and separate by silica gel column chromatography. The eluent is an ethyl acetate and petroleum ether solution to obtain the graft monomer.

[0013] Preferably, the preparation method of the carbon nanotube acyl chloride is: Immerse the carbon nanotubes in concentrated sulfuric acid and concentrated nitric acid for acidification to obtain acidified carbon nanotubes; then add them to thionyl chloride and N,N-dimethylformamide for acyl chloride reaction to obtain carbon nanotube acyl chloride.

[0014] (III) Technical effects of the present invention: The present invention uses 4-bromomethylbenzyl alcohol, acrylic acid, and 4-(phenylsulfonyl)aniline as reactants to prepare a graft monomer containing an acrylate structure. Under the action of azobisisobutyronitrile or benzoyl peroxide, graft polymerization is carried out on the nylon 6 resin, thereby introducing a diphenylsulfone polymer containing an active imino group into the nylon 6 material.

[0015] The present invention uses carbon nanotube acyl chloride and diphenylsulfone-based nylon as fillers and blends them with the nylon 6 resin. The diphenylsulfone-based nylon has good compatibility with the nylon 6 resin, and a diphenylsulfone polymer is side-chain grafted. It contains a heat-resistant benzene ring and diphenylsulfone structure. When added to the nylon 6 resin, it can improve the thermal stability of the resin plastic and increase the thermal decomposition temperature.

[0016] During the reaction of the diphenylsulfonyl nylon of the present invention, its active imino group reacts with the acyl chloride groups on the surface of the carbon nanotubes, thereby introducing nylon 6 molecular chains on the surface of the carbon nanotubes, enabling the diphenylsulfonyl nylon to act as a compatibilizer, improving the compatibility between the carbon nanotubes and the nylon 6 resin. The carbon nanotubes are uniformly dispersed in the nylon 6 resin plastic, overcoming the agglomeration problem, having a better reinforcing effect, significantly improving the tensile strength, elongation at break and flexural strength of the nylon plastic, and reducing the mass wear of the nylon plastic, improving the wear resistance. At the same time, the uniformly dispersed carbon nanotubes can improve the thermal stability of the nylon plastic, making the nylon plastic have a higher initial thermal decomposition temperature. Detailed Embodiments

[0017] The following provides a detailed description of the specific embodiments of the present invention. It should be understood that the specific embodiments described herein are only for the purpose of illustrating and explaining the present invention, and are not intended to limit the present invention.

[0018] Nylon 6 resin, Dongguan Kaiwan Engineering Plastic Raw Material Co., Ltd. Carbon nanotubes, Advanced Institute (Shenzhen) Technology Co., Ltd.

[0019] Example 1:

[0020] (1): Add 2 g of carbon nanotubes into 180 mL of concentrated sulfuric acid (mass fraction 98%) and 60 mL of concentrated nitric acid (mass fraction 68%), heat to 60 °C, stir for acidification for 4 h, filter, wash with water, and dry to obtain acidified carbon nanotubes; then add them into 300 mL of thionyl chloride, add 3 mL of N,N-dimethylformamide, heat to 70 °C, stir and react for 24 h, filter, wash with dichloromethane, and dry to obtain acyl chloride-functionalized carbon nanotubes.

[0021] (2): Add 20 mmol of 4-bromomethylbenzyl alcohol, 20 mmol of acrylic acid, 3.6 mmol of 4-dimethylaminopyridine, and 24 mmol of N,N'-dicyclohexylcarbodiimide to 40 mL of dichloromethane, stir and react at 25 °C for 7 h, concentrate under reduced pressure, and separate by silica gel column chromatography. The eluent is an ethyl acetate and petroleum ether solution to obtain an intermediate. The reaction formula is as follows:

[0022] .

[0023] (3): Add 20 mmol of the intermediate, 24 mmol of 4-(phenylsulfonyl)aniline, and 22 mmol of the catalyst 2,6-dimethylpyridine to 40 mL of N,N-dimethylacetamide. Under a nitrogen atmosphere, heat to 60 °C, stir and react for 12 h, concentrate under reduced pressure, and separate by silica gel column chromatography. The eluent is an ethyl acetate and petroleum ether solution to obtain a graft monomer. The reaction formula is:

[0024] 。

[0025] (4): Press the cleaned nylon 6 resin into a film, add it to 100 mL of ethanol, then add 0.04 g of initiator benzoyl peroxide and 15 g of graft monomer, heat to 75 °C, stir for grafting reaction for 1 h, carry out condensation reflux during the reaction, add acetone, wash with water after filtration, extract the product with acetone in a Soxhlet extractor, and dry to obtain diphenylsulfonyl nylon.

[0026] (5): Add 5 g of acyl chloride carbon nanotubes to 150 mL of toluene, stir and then add 50 g of diphenylsulfonyl nylon and 0.2 g of triethylamine, heat to 60 °C, stir and react for 12 h, concentrate under reduced pressure, wash with water, and after drying, melt-blend the product with 1 kg of nylon 6 resin and 4 g of antioxidant 1010 in an extruder. The temperatures of the first to sixth sections are 230 °C, 240 °C, 260 °C, 270 °C, 270 °C, and 265 °C, the screw speed is 200 r / min, extrude, cool, and pelletize to obtain wear-resistant modified nylon plastic.

[0027] Example 2:

[0028] (1): Add 20 mmol of 4-bromomethylbenzyl alcohol, 22 mmol of acrylic acid, 4.4 mmol of 4-dimethylaminopyridine, and 24 mmol of N,N'-dicyclohexylcarbodiimide to 50 mL of dichloromethane, stir and react at 30 °C for 4 h, concentrate under reduced pressure, and separate by silica gel column chromatography. The eluent is an ethyl acetate and petroleum ether solution to obtain an intermediate.

[0029] (2): Add 20 mmol of the intermediate, 26 mmol of 4-(phenylsulfonyl)aniline, and 24 mmol of catalyst 2,6-dimethylpyridine to 50 mL of N,N-dimethylacetamide. Under a nitrogen atmosphere, heat to 60 °C, stir and react for 12 h, concentrate under reduced pressure, and separate by silica gel column chromatography. The eluent is an ethyl acetate and petroleum ether solution to obtain a graft monomer.

[0030] (3): Press the cleaned nylon 6 resin into a film, add it to 100 mL of ethanol, then add 0.08 g of initiator benzoyl peroxide and 22 g of graft monomer, heat to 70 °C, stir for grafting reaction for 2.5 h, carry out condensation reflux during the reaction, add acetone, wash with water after filtration, extract the product with acetone in a Soxhlet extractor, and dry to obtain diphenylsulfonyl nylon.

[0031] (4): Add 30 g of acyl chloride carbon nanotubes (prepared in the same way as in Example 1) to 1200 mL of toluene. After stirring, add 200 g of diphenylsulfonyl nylon and 1.5 g of triethylamine. Heat to 40 °C and stir for 24 h. Concentrate under reduced pressure, wash with water, and after drying, melt-blend the product with 1 kg of nylon 6 resin and 4 g of antioxidant 1010 in an extruder. The temperatures of the first to sixth sections are 230 °C, 240 °C, 260 °C, 270 °C, 270 °C, and 265 °C, the screw speed is 100 r / min, extrude, cool, and pelletize to obtain wear-resistant modified nylon plastic.

[0032] Example 3:

[0033] (1): Add 20 mmol of 4-bromomethylbenzyl alcohol, 20 mmol of acrylic acid, 3.2 mmol of 4-dimethylaminopyridine, and 22 mmol of N,N'-dicyclohexylcarbodiimide to 40 mL of dichloromethane. Stir and react at 20 °C for 7 h. Concentrate under reduced pressure and separate by silica gel column chromatography. The eluent is an ethyl acetate and petroleum ether solution to obtain an intermediate.

[0034] (2): Add 20 mmol of the intermediate, 24 mmol of 4-(phenylsulfonyl)aniline, and 20 mmol of the catalyst 2,6-dimethylpyridine to 40 mL of N,N-dimethylacetamide. Under a nitrogen atmosphere, heat to 50 °C and stir for 18 h. Concentrate under reduced pressure and separate by silica gel column chromatography. The eluent is an ethyl acetate and petroleum ether solution to obtain a graft monomer.

[0035] (3): Mold the cleaned nylon 6 resin into a film, add it to 100 mL of ethanol, then add 0.12 g of the initiator azobisisobutyronitrile and 30 g of the graft monomer. Heat to 80 °C and stir for 2 h for the graft reaction. Condense and reflux during the reaction, add acetone, filter and wash with water. Extract the product with acetone in a Soxhlet extractor and dry to obtain diphenylsulfonyl nylon.

[0036] (4): Add 60 g of acyl chloride carbon nanotubes (prepared in the same way as in Example 1) to 2000 mL of toluene. After stirring, add 300 g of diphenylsulfonyl nylon and 3 g of triethylamine. Heat to 75 °C and stir for 12 h. Concentrate under reduced pressure, wash with water, and after drying, melt-blend the product with 1 kg of nylon 6 resin and 4 g of antioxidant 1010 in an extruder. The temperatures of the first to sixth sections are 230 °C, 240 °C, 260 °C, 270 °C, 270 °C, and 265 °C, the screw speed is 100 r / min, extrude, cool, and pelletize to obtain wear-resistant modified nylon plastic.

[0037] Comparative Example 1:

[0038] (1): 1 kg of nylon 6 resin and 4 g of antioxidant 1010 were melt-blended in an extruder. The temperatures of the first to sixth zones were 230 °C, 240 °C, 260 °C, 270 °C, 270 °C, and 265 °C, respectively. The screw speed was 100 r / min. After extrusion, cooling, and pelletizing, nylon plastic was obtained.

[0039] Comparative Example 2:

[0040] (1): 5 g of acyl chloride-functionalized carbon nanotubes (prepared in the same way as in Example 1), 1 kg of nylon 6 resin, and 4 g of antioxidant 1010 were melt-blended in an extruder. The temperatures of the first to sixth zones were 230 °C, 240 °C, 260 °C, 270 °C, 270 °C, and 265 °C, respectively. The screw speed was 200 r / min. After extrusion, cooling, and pelletizing, wear-resistant modified nylon plastic was obtained.

[0041] Comparative Example 3:

[0042] (1): 50 g of diphenylsulfone-based nylon (prepared in the same way as in Example 1), 1 kg of nylon 6 resin, and 4 g of antioxidant 1010 were melt-blended in an extruder. The temperatures of the first to sixth zones were 230 °C, 240 °C, 260 °C, 270 °C, 270 °C, and 265 °C, respectively. The screw speed was 200 r / min. After extrusion, cooling, and pelletizing, wear-resistant modified nylon plastic was obtained.

[0043] Comparative Example 4:

[0044] (1): 5 g of carbon nanotubes were added to 150 mL of toluene. After stirring, 50 g of diphenylsulfone-based nylon (prepared in the same way as in Example 1) and 0.2 g of triethylamine were added. The mixture was heated to 60 °C and stirred for 12 h. After concentration under reduced pressure, washing with water, and drying, the product was melt-blended with 1 kg of nylon 6 resin and 4 g of antioxidant 1010 in an extruder. The temperatures of the first to sixth zones were 230 °C, 240 °C, 260 °C, 270 °C, 270 °C, and 265 °C, respectively. The screw speed was 200 r / min. After extrusion, cooling, and pelletizing, wear-resistant modified nylon plastic was obtained.

[0045] Comparative Example 5:

[0046] (1): 5 g of acyl chloride-functionalized carbon nanotubes (prepared in the same way as in Example 1) were added to 150 mL of toluene. After stirring, 50 g of nylon 6 resin and 0.2 g of triethylamine were added. The mixture was heated to 60 °C and stirred for 12 h. After concentration under reduced pressure, washing with water, and drying, the product was melt-blended with 1 kg of nylon 6 resin and 4 g of antioxidant 1010 in an extruder. The temperatures of the first to sixth zones were 230 °C, 240 °C, 260 °C, 270 °C, 270 °C, and 265 °C, respectively. The screw speed was 200 r / min. After extrusion, cooling, and pelletizing, wear-resistant modified nylon plastic was obtained.

[0047] The wear-resistant modified nylon plastic is injection-molded into standard splines by an injection molding machine, and the temperatures of each section of the injection molding machine are 230 °C, 245 °C, and 240 °C.

[0048] The wear resistance is tested according to the standard of GB / T 3960-2016. The counter ring is a 45# steel ring, the rotation speed is 200 r / min, and the load is 200 N.

[0049] The tensile property is tested according to the standard of GB / T 1040.1-2018. The flexural property is tested according to the standard of GB / T 9341-2000.

[0050] The thermal stability is tested by a thermogravimetric analyzer. The test atmosphere is nitrogen, the test temperature is 25 - 700 °C, and the heating rate is 10 °C / min.

[0051] Table 1

[0052]

[0053] Compared with Comparative Example 1, in the nylon plastics of Examples 1 - 3, acyl chloride carbon nanotubes and diphenylsulfone-based nylon are added. The diphenylsulfone-based nylon contains a nylon 6 main chain and has good compatibility with nylon 6 resin. And the side chain is grafted with a diphenylsulfone polymer, which contains heat-resistant benzene rings and diphenylsulfone structures. When added to nylon 6 resin, it can improve the thermal stability of the resin plastic and increase the thermal decomposition temperature. At the same time, during the reaction process, the active imino group of diphenylsulfone-based nylon reacts with the acyl chloride groups on the surface of the carbon nanotubes, thereby introducing nylon 6 molecular chains on the surface of the carbon nanotubes. This enables the diphenylsulfone-based nylon to act as a compatibilizer, improving the compatibility between the carbon nanotubes and nylon 6 resin. The carbon nanotubes are uniformly dispersed in the nylon 6 resin plastic, overcoming the agglomeration problem, having a better reinforcing effect, significantly increasing the tensile strength, elongation at break, and flexural strength of the nylon plastic, and reducing the mass wear of the nylon plastic, improving the wear resistance. At the same time, the uniformly dispersed carbon nanotubes can improve the thermal stability of the nylon plastic, making the nylon plastic have a higher initial (5% mass loss) thermal decomposition temperature.

[0054] In Comparative Example 2, only acyl chloride carbon nanotubes are added. It is difficult for them to react with nylon 6 resin, and the compatibility with nylon 6 resin is poor. The dispersion of the carbon nanotubes is relatively poor, and the reinforcing effect is low. It is difficult to effectively improve the tensile strength, flexural strength, and wear resistance of the nylon plastic, and the elongation at break of the nylon plastic shows a downward trend.

[0055] Comparative Example 3 added diphenylsulfonyl nylon, which has good compatibility with the nylon 6 resin matrix and has little effect on the mechanical properties of nylon plastics. The mass wear amount, tensile strength, elongation at break, and flexural strength are very similar to those of Comparative Example 1. However, the side chain of diphenylsulfonyl nylon is grafted with a heat-resistant diphenylsulfone polymer, and when added to nylon 6 resin, it can increase the initial thermal decomposition temperature and heat resistance of the plastic.

[0056] The carbon nanotubes added in Comparative Example 4 do not contain acyl chloride groups and cannot react with diphenylsulfonyl nylon. Diphenylsulfonyl nylon cannot act as a compatibilizer, and the compatibility between carbon nanotubes and nylon 6 resin is not improved. The reinforcing effect of carbon nanotubes is poor, the mass wear amount is large, and the tensile strength, elongation at break, and flexural strength are low.

[0057] The nylon 6 resin added in Comparative Example 5 does not contain active imino groups and cannot react with acyl chloride-functionalized carbon nanotubes. The compatibility between carbon nanotubes and nylon 6 resin is not improved. The reinforcing effect of carbon nanotubes is poor, the mass wear amount is large, and the tensile strength, elongation at break, and flexural strength are low.

[0058] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, including any other suitable combination of each technical feature. These simple modifications and combinations should also be regarded as the content disclosed by the present invention and fall within the protection scope of the present invention.

Claims

1. A method for preparing wear-resistant modified nylon plastic, characterized in that: The preparation method of the wear-resistant modified nylon plastic comprises the following steps: Step A: The cleaned nylon 6 resin is molded into a film, added to ethanol, and then an initiator and a structure of The grafting monomer is stirred to carry out grafting reaction, condensed and refluxed during the reaction, acetone is added after the reaction, filtered and washed, extracted in a Soxhlet extractor, and dried to obtain diphenyl sulfone nylon; Step B: Add acyl chloride carbon nanotubes to toluene, add diphenylsulfone nylon and triethylamine after stirring, concentrate under reduced pressure after stirring for reaction, wash, dry, melt blend the product with nylon 6 resin and antioxidant in an extruder, extrude, cool and pelletize to obtain wear-resistant modified nylon plastic.

2. The method for preparing the wear-resistant modified nylon plastic according to claim 1, characterized in that: The initiator is dibenzoyl peroxide or azobisisobutyronitrile.

3. The method for preparing the wear-resistant modified nylon plastic according to claim 1, characterized in that: In the step A, the temperature during the grafting reaction is 70-80° C., and the reaction time is 1-2.5 hours.

4. The method for preparing the wear-resistant modified nylon plastic according to claim 1, characterized in that: In the step B, the masses of the chlorinated carbon nanotubes, diphenylsulfone nylon, and triethylamine are 0.5-6%, 5-30%, and 0.02-0.3% of the mass of nylon 6 resin, respectively.

5. The method for preparing the wear-resistant modified nylon plastic according to claim 1, characterized in that: In the step B, the reaction temperature is 40-75° C. and the reaction time is 12-24 h.

6. The method for preparing the wear-resistant modified nylon plastic according to claim 1, characterized in that: In the step B, the temperatures of the extruder sections 1 to 6 are 230° C., 240° C., 260° C., 270° C., 270° C., and 265° C., and the screw speed is 100-200 r / min.

7. The method for preparing the wear-resistant modified nylon plastic according to claim 1, characterized in that: The preparation method of the grafted monomer comprises the following steps: Step (1), adding 4-bromomethylbenzyl alcohol, acrylic acid, 4-dimethylaminopyridine and N,N'-dicyclohexylcarbodiimide in a molar ratio of 1:(1-1.1):(0.16-0.22):(1.1-1.2) to dichloromethane, stirring at 20-30° C. for 4-7 hours, concentrating under reduced pressure, and separating by silica gel column chromatography to obtain an intermediate; Step (2), adding the intermediate, 4-(phenylsulfonyl)aniline and 2,6-lutidine in a molar ratio of 1:(1.2-1.3):(1-1.2) to N,N-dimethylacetamide, stirring the mixture at 50-60° C. for 12-18 hours in a nitrogen atmosphere, and concentrating under reduced pressure to obtain a grafted monomer.

8. The method for preparing the wear-resistant modified nylon plastic according to claim 1, characterized in that: The preparation method of the chlorinated carbon nanotubes comprises: placing the carbon nanotubes in concentrated sulfuric acid and concentrated nitric acid for acidification to obtain acidified carbon nanotubes; and then adding the carbon nanotubes into thionyl chloride and N,N-dimethylformamide for chlorination reaction to obtain chlorinated carbon nanotubes.

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