Antistatic nylon masterbatch, its preparation method and application

Abstract

This invention discloses a method for preparing antistatic nylon masterbatch. Carbon quantum dots are directly prepared by first reacting citric acid and urea in a solid-solid mixture. These carbon quantum dots are then directly polymerized with nylon monomers under specific conditions, achieving an organic combination of nylon molecular chains and carbon dots. Simultaneously, a large number of carbon quantum dots are uniformly dispersed in the nylon, solving the problem of poor compatibility and difficulty in dispersing carbon particles in nylon. By uniformly dispersing carbon quantum dots in the nylon masterbatch and then blending it with nylon resin, the difficulty of directly synthesizing antistatic nylon resin is significantly reduced. No compatibilizer is needed; direct melt blending is possible. The carbon quantum dots act as physical crosslinking points, achieving in-situ nano-reinforcement. This results in excellent mechanical and antistatic properties and is easily mass-produced industrially.

Description

Technical Field

[0001] This invention relates to the field of polyamide composite material preparation technology, specifically to an antistatic nylon masterbatch, its preparation method, and its application. Background Technology

[0002] Nylon (polyamide) is a polymer material containing amide bonds in its molecular chain. Due to its good crystallinity and strong hydrogen bonding, it exhibits excellent mechanical strength, thermal stability, wear resistance, and corrosion resistance, making it widely used in electronics, automotive parts, industrial components, and textiles. However, because of its high electrical resistance, it is prone to static electricity buildup, which can easily lead to accidents in certain specialized fields, such as insulation materials. Therefore, it is necessary to modify its antistatic properties.

[0003] Currently, relatively mature antistatic modification technologies for polyamides mainly include blending with inorganic conductive particles, surface coating or oiling, and in-situ preparation of antistatic polymers. Among these, blending with antistatic agents is the most widely used method in the field of engineering plastics. For example, Chinese patent document CN115637044A discloses a halogen-free flame-retardant permanent antistatic polyamide composition, in which a compatibilizer, a composite permanent antistatic masterbatch, a halogen-free flame retardant, a synergistic flame retardant, an antioxidant, and a lubricant are added to polyamide resin according to a weight ratio, and then blended and extruded to obtain the corresponding antistatic nylon composition. Chinese patent document CN115216142B discloses an antistatic halogen-free flame-retardant reinforced nylon composite material, which is prepared by uniformly mixing conductive microencapsulated hypophosphite flame retardant, antioxidant, glass fiber, and nylon resin according to the required weight parts, then adding the mixture to a twin-screw extruder for melt blending, extrusion granulation, and finally obtaining the antistatic halogen-free flame-retardant reinforced nylon composite material. Chinese patent document CN115612290A discloses a low-temperature wear-resistant and antistatic polyamide composite material for ski board soles. First, wear-resistant fillers and elastomers are kneaded, extruded, and pelletized to prepare a wear-resistant modified elastomer. Then, inorganic nanofillers, conductive fillers, and antioxidants are added to a high-speed mixer for mixing. Next, polyamide matrix resin, wear-resistant modified elastomer, compatibilizer, and wear-resistant polymer are added and mixed evenly to obtain a mixture. Finally, the mixture and inorganic fibers are added to a twin-screw extruder for melt blending, extrusion, cooling, air drying, pelletizing, and drying to prepare the low-temperature wear-resistant and antistatic polyamide composite material.

[0004] However, antistatic agents have poor compatibility with polyamide resin matrices, and excessive introduction can lead to a decline in the mechanical properties of the material. Surface coating technology is mostly used in the fields of fibers and fabrics, but its disadvantage is that it is not wear-resistant. In-situ preparation affects the molecular weight of the product and it is difficult to achieve high molecular weights. Moreover, the amount of antistatic agent added is difficult to exceed 10%, because high contents result in poor melt flowability, inability to discharge, and difficulty in stirring. Therefore, in-situ preparation technology is difficult to achieve industrialization at present.

[0005] Therefore, how to improve the antistatic properties of polyamide materials while maintaining excellent mechanical properties and making them easy to mass-produce is a technical challenge in the field of polyamide insulation materials. Summary of the Invention

[0006] In view of this, the present invention provides a method for preparing antistatic nylon masterbatch, which introduces carbon quantum dots into the preparation technology to obtain antistatic nylon masterbatch. The antistatic nylon masterbatch obtained by this method has good compatibility with nylon resin, can significantly improve the antistatic properties of polyamide materials, has excellent mechanical properties, and is easy to mass-produce.

[0007] To achieve the above objectives, the present invention provides a method for preparing antistatic nylon masterbatch, comprising the following steps:

[0008] (1) After mixing urea and citric acid solid-solid evenly, react at 120-250℃ for 15-60 min in a nitrogen atmosphere, then cool to room temperature, add deionized water and mix well to obtain a suspension of carbon quantum dots.

[0009] (2) In an inert gas atmosphere, an aqueous solution of diamine, diacid, catalyst, lubricant and antioxidant is reacted with a suspension of carbon quantum dots at pH 7.0-7.5 and 80-100°C for 0.5-2 hours, and then the temperature is raised to 170-220°C and reacted for 1-3 hours to obtain a carbon quantum dot / polyamide composite prepolymer.

[0010] (3) The carbon quantum dot / polyamide composite prepolymer is cooled to normal pressure and heated to 230-280°C. Then, it is evacuated to a vacuum state under constant temperature (the vacuum degree recommended by this invention is -0.086 to -0.092 MPa). The reaction continues until the viscosity of the system reaches 2.2-2.6. After cooling and pelletizing, the antistatic nylon masterbatch is obtained.

[0011] The catalyst is a mixture of iron(III) oxide and disodium hydrogen phosphate.

[0012] Optionally, in the preparation method of the antistatic nylon masterbatch provided by the present invention, by weight, the urea is 10-20 parts, the citric acid is 10-20 parts, the diamine is 100 parts, the diacid is 90-200 parts, the lubricant is 2-5 parts, the catalyst is 0.5-1 parts, and the antioxidant is 0.5-1 parts.

[0013] Optionally, in the method for preparing antistatic nylon masterbatch provided by the present invention, the mass ratio of ferric oxide to disodium hydrogen phosphate is 1:1 to 1:3.

[0014] Optionally, in step (3) of the method for preparing antistatic nylon masterbatch provided by the present invention, the reaction continues for 5 to 20 minutes until the set system viscosity is reached.

[0015] Optionally, in step (2) of the method for preparing antistatic nylon masterbatch provided by the present invention, the pH is adjusted by using the diamine or the dicarboxylic acid.

[0016] Optionally, in step (3) of the method for preparing antistatic nylon masterbatch provided by the present invention, the carbon quantum dot / polyamide composite prepolymer is cooled to atmospheric pressure and heated to 230-280°C within 30-120 minutes;

[0017] In step (3), the vacuuming rate is (0.01~0.03) MPa / 10min.

[0018] Optionally, in the method for preparing antistatic nylon masterbatch provided by the present invention, the diamine is selected from any one of pentanediamine, hexanediamine, nonanediamine, decanediamine and dodecanediamine;

[0019] The dicarboxylic acid is selected from any one of succinic acid, adipic acid, sebacic acid, and dodecanoic acid;

[0020] The antioxidant is selected from one or more of antioxidant 1010, antioxidant H3322, antioxidant H3332, antioxidant 168, and antioxidant SEED;

[0021] The lubricant is selected from silicone oil and / or stearic acid.

[0022] The method for preparing the antistatic nylon masterbatch provided by the present invention can be designed and adjusted according to the needs of subsequent applications (such as the thermal properties of the nylon resin to be modified), so as to control the length of the structural units of the antistatic nylon masterbatch and control its melting point to be lower than that of the nylon resin to be modified, so as to adapt to the antistatic processing modification of various nylons.

[0023] The present invention also provides an antistatic nylon masterbatch, which is prepared by the above-described method for preparing antistatic nylon masterbatch.

[0024] This invention also provides an antistatic nylon composite material, comprising an antistatic nylon masterbatch prepared by the above-described method and nylon resin, wherein the melting point of the antistatic nylon masterbatch is lower than that of the nylon resin; preferably, the nylon resin is selected from any one of nylon 56, nylon 66, nylon 12, and nylon 6. Additives can be added later according to different requirements.

[0025] Optionally, in the antistatic nylon composite material provided by the present invention, the antistatic nylon masterbatch comprises 10 to 40 parts by weight, and the nylon resin comprises 60 to 90 parts by weight.

[0026] The present invention also provides a method for preparing the above-mentioned antistatic nylon composite material, comprising the following steps: mixing the antistatic nylon masterbatch with the nylon resin, and then performing melt blending extrusion using a screw extruder, wherein the screw temperature is 170-280℃ and the rotation speed is 40-60 r / min.

[0027] Compared with the prior art, the present invention has at least the following beneficial effects:

[0028] The method for preparing antistatic nylon masterbatch provided by this invention involves first preparing carbon quantum dots through a solid-solid mixing reaction of citric acid and urea, and controlling the type and quantity of surface groups on the carbon dots by utilizing the raw materials and reaction temperature. Then, the carbon quantum dots are directly polymerized in situ with nylon monomers under specific conditions to achieve the organic combination of nylon molecular chains and carbon dots, while uniformly dispersing a large number of carbon quantum dots in nylon, thus perfectly solving the problem of poor compatibility and difficulty in dispersion of carbon dot particles in nylon.

[0029] By uniformly dispersing carbon quantum dots in nylon masterbatch and then blending them with nylon resin, the difficulty of directly synthesizing antistatic nylon resin is significantly reduced. Furthermore, because the antistatic nylon masterbatch and nylon resin have similar matrix structures, no compatibilizer is needed; they can be directly melt-blended, and the masterbatch promotes nylon crystallization and forms hydrogen bonds with the resin. The antistatic nylon composite material obtained by mixing the antistatic nylon masterbatch and nylon resin prepared using the method provided by this invention utilizes carbon quantum dots as physical crosslinking points, achieving in-situ nano-reinforcement. This composite material exhibits excellent mechanical and antistatic properties and is easily mass-produced industrially. Detailed Implementation

[0030] The present invention will now be described in detail through embodiments. It should be noted that the following embodiments are only for further illustration of the present invention and should not be construed as limiting the scope of protection of the present invention. Those skilled in the art can make some non-essential improvements and adjustments to the present invention based on the above description.

[0031] Unless otherwise specified, all raw materials and reagents involved in this invention are commercially available, and all commercially available raw materials and reagents can meet the requirements for implementing the technical solution of this invention.

[0032] Example 1

[0033] This embodiment provides an antistatic nylon composite material, the preparation method of which includes the following steps:

[0034] Antistatic nylon masterbatch:

[0035] (1) Grind 20 parts by weight of urea and 20 parts by weight of citric acid thoroughly to make their particle size similar and evenly dispersed. Then add them to the reaction vessel, replace the air in the vessel with nitrogen, and quickly raise the temperature to 200°C. Keep the temperature constant for 60 min, then slowly lower it to room temperature. Add 40 parts by weight of deionized water, turn on the stirrer and set the speed to 200 r / min. Disperse the generated carbon quantum dots evenly in the water to obtain a suspension of carbon quantum dots.

[0036] (2) Dissolve 135.87 parts by weight of adipic acid and 100 parts by weight of pentanediamine in 100 parts of deionized water, then add 2 parts by weight of silicone oil, 0.5 parts by weight of catalyst (the mass ratio of iron oxide and disodium hydrogen phosphate is 1:1, and they are ground and mixed) and 0.5 parts by weight of antioxidant (antioxidant H3322). After mixing evenly, add it to the reaction vessel containing the suspension of carbon quantum dots. Adjust the pH of the system to 7.2 using pentanediamine. After replacing the air in the vessel with nitrogen, start stirring, set the speed to 80 r / min, slowly raise the temperature to 80℃ and keep it at a constant temperature for 1 h, then raise the temperature to 210℃ and keep it at a constant temperature for 3 h.

[0037] (3) Open the vent valve to release water vapor and unreacted monomers or byproducts (takes 60 min), and control the temperature to slowly rise to 260℃ while restoring the system to normal pressure;

[0038] (4) After the system is restored to normal pressure, vacuum is drawn at a constant temperature of 260℃. The vacuum degree increases by 0.020MPa every 10min until it reaches -0.090MPa. Under this condition, the reaction continues for 5min until the system viscosity reaches 2.2. Then, nitrogen is introduced to restore normal pressure, and the material is discharged, cast into a strip, cooled, and pelletized to obtain antistatic nylon masterbatch.

[0039] Antistatic nylon composite material:

[0040] After drying the above antistatic nylon masterbatch in a vacuum oven at 90°C for 6 hours, 25 parts by weight and 75 parts by weight of nylon 56 were weighed and mixed evenly. The mixture was then melt-blended in a twin-screw extruder at temperatures of 265°C, 270°C, and 260°C and a rotation speed of 45 r / min. After extrusion and pelletizing, the antistatic nylon 56 composite material was obtained.

[0041] Example 2

[0042] This embodiment provides an antistatic nylon composite material, the preparation method of which includes the following steps:

[0043] Antistatic nylon masterbatch:

[0044] (1) Grind 20 parts by weight of urea and 20 parts by weight of citric acid thoroughly to make their particle size similar and evenly dispersed. Then add them to the reaction vessel, replace the air in the vessel with nitrogen, and quickly raise the temperature to 200°C. Keep the temperature constant for 60 min, then slowly lower it to room temperature. Add 40 parts by weight of deionized water, turn on the stirrer and set the speed to 200 r / min. Disperse the generated carbon quantum dots evenly in the water to obtain a suspension of carbon quantum dots.

[0045] (2) Dissolve 197.93 parts by weight of sebacic acid and 100 parts by weight of pentanediamine in 120 parts of deionized water, then add 5 parts by weight of silicone oil, 0.5 parts by weight of catalyst (the mass ratio of iron oxide and disodium hydrogen phosphate is 1:1, and they are ground and mixed) and 0.5 parts by weight of antioxidant (antioxidant H3322). After mixing evenly, add it to a reaction vessel containing a suspension of carbon quantum dots. Adjust the pH of the system to 7.5 using pentanediamine. After replacing the air in the vessel with nitrogen, start stirring, set the speed to 80 r / min, slowly raise the temperature to 80℃ and keep it at a constant temperature for 1 h, then raise the temperature to 190℃ and keep it at a constant temperature for 2.5 h.

[0046] (3) Open the vent valve to release water vapor and unreacted monomers or byproducts (takes 35 minutes), and control the temperature to rise slowly to 230°C and restore the system to normal pressure;

[0047] (4) After the system is restored to normal pressure, vacuum is drawn at a constant temperature of 230℃. The vacuum degree increases by 0.020MPa every 10min until it reaches -0.090MPa. Under this condition, the reaction continues for 10min until the system viscosity reaches 2.6. Nitrogen is then introduced to restore normal pressure. The material is discharged, cast into a strip, cooled, and pelletized to obtain antistatic nylon masterbatch.

[0048] Antistatic nylon composite material:

[0049] After drying the above-mentioned antistatic nylon masterbatch in a vacuum oven at 90°C for 6 hours, 25 parts by weight and 75 parts by weight of nylon 56 were weighed and mixed evenly. The mixture was then melt-blended in a twin-screw extruder at temperatures of 260°C, 265°C, and 255°C and a rotation speed of 45 r / min. After extrusion and pelletizing, the antistatic nylon 56 composite material was obtained.

[0050] Example 3

[0051] This embodiment provides an antistatic nylon composite material, the preparation method of which includes the following steps:

[0052] Antistatic nylon masterbatch:

[0053] (1) Grind 20 parts by weight of urea and 20 parts by weight of citric acid thoroughly to make their particle size similar and evenly dispersed. Then add them to the reaction vessel, replace the air in the vessel with nitrogen, and quickly raise the temperature to 200°C. Keep the temperature constant for 60 min, then slowly lower it to room temperature. Add 40 parts by weight of deionized water, turn on the stirrer and set the speed to 200 r / min. Disperse the generated carbon quantum dots evenly in the water to obtain a suspension of carbon quantum dots.

[0054] (2) Dissolve 117.44 parts by weight of sebacic acid and 100 parts by weight of decanediamine in 100 parts of deionized water, then add 5 parts by weight of silicone oil, 0.5 parts by weight of catalyst (the mass ratio of iron oxide and disodium hydrogen phosphate is 1:1, and they are ground and mixed) and 0.5 parts by weight of antioxidant (antioxidant H3322). After mixing evenly, add it to the reaction vessel containing the suspension of carbon quantum dots. Adjust the pH of the system to 7.2 using decanediamine. After replacing the air in the vessel with nitrogen, start stirring, set the speed to 80 r / min, slowly raise the temperature to 100℃ and keep it at a constant temperature for 1 h, then raise the temperature to 170℃ and keep it at a constant temperature for 2 h.

[0055] (3) Open the vent valve to release water vapor and unreacted monomers or byproducts (takes 80 min), and control the temperature to slowly rise to 280℃ and restore the system to normal pressure;

[0056] (4) After the system is restored to normal pressure, vacuum is drawn at a constant temperature of 280℃. The vacuum degree increases by 0.020MPa every 10min until it reaches -0.086MPa. Under this condition, the reaction continues for 10min until the system viscosity reaches 2.3. Then, nitrogen is introduced to restore normal pressure, and the material is discharged, cast into a strip, cooled, and pelletized to obtain antistatic nylon masterbatch.

[0057] Antistatic nylon composite material:

[0058] After drying the above-mentioned antistatic nylon masterbatch in a vacuum oven at 90°C for 6 hours, 25 parts by weight and 75 parts by weight of nylon 56 were weighed and mixed evenly. The mixture was then melt-blended in a twin-screw extruder at temperatures of 260°C, 265°C, and 255°C and a rotation speed of 45 r / min. After extrusion and pelletizing, the antistatic nylon 56 composite material was obtained.

[0059] Example 4

[0060] This embodiment provides an antistatic nylon composite material, the preparation method of which includes the following steps:

[0061] Antistatic nylon masterbatch:

[0062] (1) Grind 10 parts by weight of urea and 10 parts by weight of citric acid thoroughly to make their particle size similar and evenly dispersed. Then add them to the reaction vessel, replace the air in the vessel with nitrogen, and quickly raise the temperature to 200°C. Keep the temperature constant for 60 min, then slowly lower it to room temperature. Add 40 parts by weight of deionized water, turn on the stirrer and set the speed to 200 r / min. Disperse the generated carbon quantum dots evenly in the water to obtain a suspension of carbon quantum dots.

[0063] (2) Dissolve 90 parts by weight of succinic acid and 100 parts by weight of hexamethylenediamine in 100 parts of deionized water, then add 3 parts by weight of silicone oil, 1 part by weight of catalyst (the mass ratio of iron oxide and disodium hydrogen phosphate is 1:1, and they are ground and mixed) and 1 part by weight of antioxidant (antioxidant H3322). After mixing evenly, add it to a reaction vessel containing a suspension of carbon quantum dots. Adjust the pH of the system to 7.5 with adipic acid. After replacing the air in the vessel with nitrogen, start stirring, set the speed to 80 r / min, slowly raise the temperature to 80℃ and keep it at a constant temperature for 0.5 h, then raise the temperature to 190℃ and keep it at a constant temperature for 2.5 h.

[0064] (3) Open the vent valve to release water vapor and unreacted monomers or byproducts (takes 100 min), and control the temperature to slowly rise to 240℃ and restore the system to normal pressure;

[0065] (4) After the system is restored to normal pressure, vacuum is drawn at a constant temperature of 240℃. The vacuum degree increases by 0.020MPa every 10min until it reaches -0.088MPa. Under this condition, the reaction continues for 5min until the system viscosity reaches 2.3. Then, nitrogen is introduced to restore normal pressure, and the material is discharged, cast into a strip, cooled, and pelletized to obtain antistatic nylon masterbatch.

[0066] Antistatic nylon composite material:

[0067] After drying the above-mentioned antistatic nylon masterbatch in a vacuum oven at 90°C for 6 hours, 15 parts by weight were weighed and mixed evenly with 85 parts by weight of nylon 66. The mixture was then melt-blended in a twin-screw extruder at temperatures of 270°C, 275°C, and 265°C and a rotation speed of 55 r / min. After extrusion and pelletizing, the antistatic nylon 66 composite material was obtained.

[0068] Example 5

[0069] This embodiment provides an antistatic nylon composite material, the preparation method of which includes the following steps:

[0070] Antistatic nylon masterbatch:

[0071] (1) Grind 10 parts by weight of urea and 20 parts by weight of citric acid thoroughly to make their particle size similar and evenly dispersed. Then add them to the reaction vessel, replace the air in the vessel with nitrogen, and quickly raise the temperature to 200°C. Keep the temperature constant for 60 min, then slowly lower it to room temperature. Add 40 parts by weight of deionized water, turn on the stirrer and set the speed to 200 r / min. Disperse the generated carbon quantum dots evenly in the water to obtain a suspension of carbon quantum dots.

[0072] (2) Dissolve 117.39 parts by weight of sebacic acid and 100 parts by weight of pentanediamine in 120 parts of deionized water, then add 5 parts by weight of silicone oil, 0.8 parts by weight of catalyst (the mass ratio of iron oxide to disodium hydrogen phosphate is 1:2, and they are ground and mixed) and 1.0 parts by weight of antioxidant (antioxidant 1010). After mixing evenly, add it to the reaction vessel containing the suspension of carbon quantum dots. Adjust the pH of the system to 7.5 using pentanediamine. After replacing the air in the vessel with nitrogen, start stirring, set the speed to 80 r / min, slowly raise the temperature to 90℃ and keep it at a constant temperature for 1.5 h, then raise the temperature to 190℃ and keep it at a constant temperature for 2.5 h.

[0073] (3) Open the vent valve to release water vapor and unreacted monomers or byproducts (takes 120 min), and control the temperature to rise slowly to 270°C and restore the system to normal pressure;

[0074] (4) After the system is restored to normal pressure, vacuum is drawn at a constant temperature of 270℃. The vacuum degree increases by 0.020MPa every 10min until it reaches -0.090MPa. Under this condition, the reaction continues for 15min until the system viscosity reaches 2.5. Then, nitrogen is introduced to restore normal pressure, and the material is discharged, cast into a strip, cooled, and pelletized to obtain antistatic nylon masterbatch.

[0075] Antistatic nylon composite material:

[0076] After drying the above-mentioned antistatic nylon masterbatch in a vacuum oven at 90°C for 6 hours, 30 parts by weight and 70 parts by weight of nylon 66 were weighed and mixed evenly. The mixture was then melt-blended in a twin-screw extruder at temperatures of 270°C, 275°C, and 265°C and a rotation speed of 55 r / min. After extrusion and pelletizing, the antistatic nylon 66 composite material was obtained.

[0077] Example 6

[0078] This embodiment provides an antistatic nylon composite material, the preparation method of which includes the following steps:

[0079] Antistatic nylon masterbatch:

[0080] (1) Grind 20 parts by weight of urea and 10 parts by weight of citric acid thoroughly to make their particle size similar and evenly dispersed. Then add them to the reaction vessel, replace the air in the vessel with nitrogen, and quickly raise the temperature to 200°C. Keep the temperature constant for 60 minutes, then slowly lower it to room temperature. Add 40 parts by weight of deionized water, turn on the stirrer and set the speed to 200 r / min to evenly disperse the generated carbon quantum dots in the water to obtain a suspension of carbon quantum dots.

[0081] (2) Dissolve 154.77 parts by weight of sebacic acid and 100 parts by weight of decanediamine in 100 parts of deionized water, then add 5 parts by weight of silicone oil lubricant, 0.5 parts by weight of catalyst (the mass ratio of iron oxide to disodium hydrogen phosphate is 1:3, and they are ground and mixed), and 0.5 parts by weight of antioxidant (the mass ratio of antioxidant H3322 to antioxidant H3332 is 1:1). After mixing evenly, add it to the reaction vessel containing the suspension of carbon quantum dots. Adjust the pH of the system to 7.2 using decanediamine. After replacing the air in the vessel with nitrogen, start stirring, set the speed to 80 r / min, slowly raise the temperature to 100℃ and keep it at a constant temperature for 1 h, then raise the temperature to 210℃ and keep it at a constant temperature for 1 h.

[0082] (3) Open the vent valve to release water vapor and unreacted monomers or byproducts (takes 90 min), and control the temperature to rise slowly to 230℃ while the system returns to normal pressure;

[0083] (4) After the system is restored to normal pressure, vacuum is drawn at a constant temperature of 230℃. The vacuum degree increases by 0.010MPa every 10min until it reaches -0.091MPa. Under this condition, the reaction continues for 10min until the system viscosity reaches 2.3. Then, nitrogen is introduced to restore normal pressure, and the material is discharged, cast into a strip, cooled, and pelletized to obtain antistatic nylon masterbatch.

[0084] Antistatic nylon composite material:

[0085] After drying the above-mentioned antistatic nylon masterbatch in a vacuum oven at 90°C for 6 hours, 40 parts by weight and 60 parts by weight of nylon 66 were weighed and mixed evenly. The mixture was then melt-blended in a twin-screw extruder at temperatures of 270°C, 275°C, and 265°C and a rotation speed of 55 r / min. After extrusion and pelletizing, the antistatic nylon 66 composite material was obtained.

[0086] Example 7

[0087] This embodiment provides an antistatic nylon composite material, the preparation method of which includes the following steps:

[0088] Antistatic nylon masterbatch:

[0089] (1) Grind 15 parts by weight of urea and 15 parts by weight of citric acid thoroughly to make their particle size similar and evenly dispersed. Then add them to the reaction vessel, replace the air in the vessel with nitrogen, and quickly raise the temperature to 200°C. Keep the temperature constant for 60 min, then slowly lower it to room temperature. Add 40 parts by weight of deionized water, turn on the stirrer and set the speed to 200 r / min. Disperse the generated carbon quantum dots evenly in the water to obtain a suspension of carbon quantum dots.

[0090] (2) Dissolve 177.93 parts by weight of sebacic acid and 100 parts by weight of pentanediamine in 120 parts of deionized water, then add 5 parts by weight of silicone oil, 0.5 parts by weight of catalyst (the mass ratio of iron oxide to disodium hydrogen phosphate is 1:1, and they are ground and mixed) and 0.5 parts by weight of antioxidant (the mass ratio of antioxidant 1010 to antioxidant 168 is 2:1). After mixing evenly, add it to a reactor containing a suspension of carbon quantum dots. Adjust the pH of the system to 7.5 using pentanediamine. After replacing the air in the reactor with nitrogen, start stirring, set the speed to 80 r / min, slowly raise the temperature to 85°C and keep it at a constant temperature for 2 hours, then raise the temperature to 190°C and keep it at a constant temperature for 2 hours.

[0091] (3) Open the vent valve to release water vapor and unreacted monomers or byproducts (takes 40 minutes), and control the temperature to rise slowly to 230°C and restore the system to normal pressure;

[0092] (4) After the system is restored to normal pressure, vacuum is drawn at a constant temperature of 230℃. The vacuum degree increases by 0.030MPa every 10min until it reaches -0.092MPa. Under this condition, the reaction continues for 10min until the system viscosity reaches 2.4. Nitrogen is then introduced to restore normal pressure. The material is discharged, cast into a strip, cooled, and pelletized to obtain antistatic nylon masterbatch.

[0093] Antistatic nylon composite material:

[0094] After drying the above antistatic nylon masterbatch in a vacuum oven at 90°C for 6 hours, 15 parts by weight were weighed and mixed evenly with 85 parts by weight of nylon 6. The mixture was then melt-blended in a twin-screw extruder at temperatures of 230°C, 235°C, and 230°C, and a rotation speed of 55 r / min. After extrusion and pelletizing, the antistatic nylon 6 composite material was obtained.

[0095] Example 8

[0096] This embodiment provides an antistatic nylon composite material, the preparation method of which includes the following steps:

[0097] Antistatic nylon masterbatch:

[0098] (1) Grind 20 parts by weight of urea and 20 parts by weight of citric acid thoroughly to make their particle size similar and evenly dispersed. Then add them to the reaction vessel, replace the air in the vessel with nitrogen, and quickly raise the temperature to 200°C. Keep the temperature constant for 60 min, then slowly lower it to room temperature. Add 40 parts by weight of deionized water, turn on the stirrer and set the speed to 200 r / min. Disperse the generated carbon quantum dots evenly in the water to obtain a suspension of carbon quantum dots.

[0099] (2) Dissolve 117.44 parts by weight of sebacic acid and 100 parts by weight of decanediamine in 100 parts of deionized water, then add 5 parts by weight of silicone oil lubricant, 0.5 parts by weight of catalyst (the mass ratio of iron oxide and disodium hydrogen phosphate is 1:1, and they are ground and mixed) and 0.8 parts by weight of antioxidant (antioxidant H3332). After mixing evenly, add it to the reaction vessel containing the suspension of carbon quantum dots. Adjust the pH of the system to 7.2 using decanediamine. After replacing the air in the vessel with nitrogen, start stirring, set the speed to 80 r / min, slowly raise the temperature to 100℃ and keep it at a constant temperature for 1 h, then raise the temperature to 170℃ and keep it at a constant temperature for 2.5 h.

[0100] (3) Open the vent valve to release water vapor and unreacted monomers or byproducts (takes 40 minutes), and control the temperature to rise slowly to 230°C and restore the system to normal pressure;

[0101] (4) After the system is restored to normal pressure, vacuum is drawn at a constant temperature of 230℃. The vacuum degree increases by 0.020MPa every 10min until it reaches -0.090MPa. Under this condition, the reaction continues for 20min until the system viscosity reaches 2.3. Then, nitrogen is introduced to restore normal pressure, and the material is discharged, cast into a strip, cooled, and pelletized to obtain antistatic nylon masterbatch.

[0102] Antistatic nylon composite material:

[0103] After drying the above-mentioned antistatic nylon masterbatch in a vacuum oven at 90°C for 6 hours, 15 parts by weight were weighed and mixed evenly with 85 parts by weight of nylon 12. The mixture was then melt-blended in a twin-screw extruder at temperatures of 180°C, 195°C, and 185°C and a rotation speed of 55 r / min. After extrusion and pelletizing, the antistatic nylon 12 composite material was obtained.

[0104] Comparative Example 1

[0105] This comparative example is similar to Example 1, except that the reaction temperature in step (1) of preparing the antistatic nylon masterbatch is different. The specific process of step (1) of preparing the antistatic nylon masterbatch in this comparative example is as follows:

[0106] (1) Grind 20 parts by weight of urea and 20 parts by weight of citric acid thoroughly to make their particle size similar and evenly dispersed. Then add them to the reaction vessel, replace the air in the vessel with nitrogen, and quickly raise the temperature to 100°C. Keep the temperature constant for 60 minutes, then slowly lower it to room temperature. Add 40 parts by weight of deionized water, turn on the stirrer and set the speed to 200 r / min to evenly disperse the generated carbon quantum dots in the water to obtain a suspension of carbon quantum dots.

[0107] Comparative Example 2

[0108] This comparative example is similar to Example 1, except that the reaction temperature in step (1) of preparing the antistatic nylon masterbatch is different. The specific process of step (1) of preparing the antistatic nylon masterbatch in this comparative example is as follows:

[0109] (1) Grind 20 parts by weight of urea and 20 parts by weight of citric acid thoroughly to make their particle size similar and evenly dispersed. Then add them to the reaction vessel, replace the air in the vessel with nitrogen, and quickly raise the temperature to 300°C. Keep the temperature constant for 60 min, then slowly lower it to room temperature. Add 40 parts by weight of deionized water, turn on the stirrer and set the speed to 200 r / min. Disperse the generated carbon quantum dots evenly in the water to obtain a suspension of carbon quantum dots.

[0110] Comparative Example 3

[0111] This comparative example is similar to Example 1, except that the reaction time in step (1) of preparing the antistatic nylon masterbatch is different. The specific process of step (1) of preparing the antistatic nylon masterbatch in this comparative example is as follows:

[0112] (1) Grind 20 parts by weight of urea and 20 parts by weight of citric acid thoroughly to make their particle size similar and evenly dispersed. Then add them to the reaction vessel, replace the air in the vessel with nitrogen, and quickly raise the temperature to 200°C. Keep the temperature constant for 10 minutes, then slowly lower it to room temperature. Add 40 parts by weight of deionized water, turn on the stirrer and set the speed to 200 r / min to evenly disperse the generated carbon quantum dots in the water to obtain a suspension of carbon quantum dots.

[0113] Comparative Example 4

[0114] This comparative example is similar to Example 1, except that the reaction time in step (1) of preparing the antistatic nylon masterbatch is different. The specific process of step (1) of preparing the antistatic nylon masterbatch in this comparative example is as follows:

[0115] (1) Grind 20 parts by weight of urea and 20 parts by weight of citric acid thoroughly to make their particle size similar and evenly dispersed. Then add them to the reaction vessel, replace the air in the vessel with nitrogen, and quickly raise the temperature to 200°C. Keep the temperature constant for 80 minutes, then slowly lower it to room temperature. Add 40 parts by weight of deionized water, turn on the stirrer and set the speed to 200 r / min. Disperse the generated carbon quantum dots evenly in the water to obtain a suspension of carbon quantum dots.

[0116] Comparative Example 5

[0117] This comparative example is similar to Example 1, except that the pH adjustment step is omitted in step (2) of preparing the antistatic nylon masterbatch. The specific process of step (2) of preparing the antistatic nylon masterbatch in this comparative example is as follows:

[0118] Dissolve 135.87 parts by weight of adipic acid and 100 parts by weight of pentanediamine in 100 parts by weight of deionized water. Then add 2 parts by weight of silicone oil lubricant, 0.5 parts by weight of catalyst (ferric oxide and disodium hydrogen phosphate in a mass ratio of 1:1, ground and mixed), and 0.5 parts by weight of antioxidant (antioxidant H3322). After mixing evenly, add the mixture to a reactor containing a suspension of carbon quantum dots. Replace the air in the reactor with nitrogen, start stirring, set the speed to 80 r / min, slowly raise the temperature to 80℃ and keep it at a constant temperature for 1 hour, then raise the temperature to 210℃ and keep it at a constant temperature for 3 hours.

[0119] Comparative Example 6

[0120] This comparative example is similar to Example 1, except that the amount of adipic acid used in step (2) of preparing the antistatic nylon masterbatch is different, and the pH adjustment step is omitted. The specific process of step (2) of the antistatic nylon masterbatch in this comparative example is as follows:

[0121] Dissolve 114.42 parts by weight of adipic acid and 100 parts by weight of pentanediamine in 100 parts by weight of deionized water. Then add 2 parts by weight of silicone oil lubricant, 0.5 parts by weight of catalyst (ferric oxide and disodium hydrogen phosphate in a mass ratio of 1:1, ground and mixed), and 0.5 parts by weight of antioxidant (antioxidant H3322). After mixing evenly, add the mixture to a reactor containing a suspension of carbon quantum dots. Replace the air in the reactor with nitrogen, start stirring, set the speed to 80 r / min, slowly raise the temperature to 80℃ and keep it at a constant temperature for 1 hour, then raise the temperature to 210℃ and keep it at a constant temperature for 3 hours.

[0122] Comparative Example 7

[0123] This comparative example is similar to Example 1, except that the catalyst used in step (2) of preparing the antistatic nylon masterbatch is different. In this comparative example, 0.5 parts by weight of iron(III) oxide is used instead of 0.5 parts by weight of the mixture of iron(III) oxide and disodium hydrogen phosphate in a mass ratio of 1:1 in Example 1.

[0124] Comparative Example 8

[0125] This comparative example is similar to Example 1, except that the catalyst used in step (2) of preparing the antistatic nylon masterbatch is different. In this comparative example, 0.5 parts by weight of disodium hydrogen phosphate is used instead of 0.5 parts by weight of the mixture of iron(III) oxide and disodium hydrogen phosphate in a mass ratio of 1:1 in Example 1.

[0126] Comparative Example 9

[0127] This comparative example provides an antistatic nylon composite material, the preparation method of which includes the following steps:

[0128] Antistatic nylon masterbatch: Same as in Example 1.

[0129] Antistatic nylon composite material: After drying the above-mentioned antistatic nylon masterbatch in a vacuum oven at 90°C for 6 hours, weigh 25 parts by weight and mix them evenly with 75 parts by weight of nylon 6. Melt-blend in a twin-screw extruder with twin-screw temperatures of 230°C, 235°C, and 230°C and a rotation speed of 50 r / min. After extrusion and pelletizing, antistatic nylon 6 composite material is obtained.

[0130] Comparative Example 10

[0131] This comparative example provides an antistatic nylon composite material, the preparation method of which includes the following steps:

[0132] Antistatic nylon masterbatch: Same as in Example 1.

[0133] Antistatic nylon composite material:

[0134] After drying the above-mentioned antistatic nylon masterbatch in a vacuum oven at 90°C for 6 hours, 25 parts by weight and 75 parts by weight of nylon 12 were weighed and mixed evenly. The mixture was then melt-blended in a twin-screw extruder at temperatures of 180°C, 195°C, and 185°C and a rotation speed of 50 r / min. After extrusion and pelletizing, the antistatic nylon 12 composite material was obtained.

[0135] Comparative Example 11

[0136] This comparative example provides an antistatic nylon composite material, the preparation method of which includes the following steps:

[0137] (1) Grind 20 parts by weight of urea and 20 parts by weight of citric acid thoroughly to make their particle size similar and evenly dispersed. Add them to the reaction vessel, replace the air in the vessel with nitrogen, and then rapidly heat to 200°C. React at a constant temperature for 60 minutes, and then slowly cool down to room temperature. Grind the obtained carbon quantum dots to obtain uniform inorganic nanoparticles.

[0138] (2) 90 parts by weight of nylon 56 and 10 parts by weight of the above carbon quantum dots (inorganic nanoparticles) were mixed at high speed and then melt-blended in a twin-screw extruder. The twin-screw temperatures were 265℃, 270℃ and 260℃, and the rotation speed was 50 r / min. After extrusion and pelletizing, antistatic nylon 56 composite material was prepared.

[0139] Comparative Example 12

[0140] This comparative example provides an antistatic nylon composite material, the preparation method of which includes the following steps:

[0141] Antistatic nylon masterbatch:

[0142] (1) Grind 20 parts by weight of polyethylene glycol and 20 parts by weight of citric acid thoroughly to make their particle size similar and evenly dispersed. Then add them to the reaction vessel, replace the air in the vessel with nitrogen, and then rapidly heat to 200°C. Keep the temperature constant for 60 min, then slowly cool to room temperature, add 40 parts by weight of deionized water, turn on the stirrer and set the speed to 200 r / min to evenly disperse the generated carbon quantum dots in the water to obtain a suspension of carbon quantum dots.

[0143] Steps (2), (3), and (4) and the preparation steps of the antistatic nylon composite material are the same as those in Example 1, except that the above-mentioned antistatic nylon masterbatch is used in this comparative example.

[0144] Comparative Example 13

[0145] This comparative example is similar to Example 1, except that the method for preparing the antistatic nylon masterbatch is different. The preparation method of the antistatic nylon masterbatch in this comparative example includes the following steps:

[0146] (1) Grind 20 parts by weight of urea and 20 parts by weight of citric acid thoroughly to make their particle size similar and evenly dispersed. Then add them to the reaction vessel, replace the air in the vessel with nitrogen, and quickly raise the temperature to 200°C. Keep the temperature constant for 60 min, then slowly lower it to room temperature. Add 40 parts by weight of deionized water, turn on the stirrer and set the speed to 200 r / min. Disperse the generated carbon quantum dots evenly in the water to obtain a suspension of carbon quantum dots.

[0147] (2) Dissolve 135.87 parts by weight of adipic acid and 100 parts by weight of pentanediamine in 100 parts of deionized water, then add 2 parts by weight of silicone oil, 0.5 parts by weight of catalyst (the mass ratio of iron oxide and disodium hydrogen phosphate is 1:1, and they are ground and mixed) and 0.5 parts by weight of antioxidant (antioxidant H3322). After mixing evenly, add it to the reaction vessel containing the suspension of carbon quantum dots. Adjust the pH of the system to 7.2 using pentanediamine. After replacing the air in the vessel with nitrogen, start stirring, set the speed to 80 r / min, and slowly raise the temperature to 210℃ and react at a constant temperature for 3 hours.

[0148] (3) Open the vent valve to release water vapor and unreacted monomers or byproducts (takes 60 min), and control the temperature to slowly rise to 260℃ while restoring the system to normal pressure;

[0149] (4) After the system is restored to normal pressure, vacuum is drawn at a constant temperature of 260℃. The vacuum degree increases by 0.020MPa every 10min until it reaches -0.090MPa. Under this condition, the reaction continues for 5min until the system viscosity reaches 2.2. Then, nitrogen is introduced to restore normal pressure, and the material is discharged, cast into a strip, cooled, and pelletized to obtain antistatic nylon masterbatch.

[0150] Comparative Example 14

[0151] This comparative example is similar to Example 1, except that step (1) in preparing the antistatic nylon masterbatch is different. The preparation method of the antistatic nylon masterbatch in this comparative example includes the following steps:

[0152] (1) Dissolve 20 parts by weight of urea and 20 parts by weight of citric acid in 40 parts by weight of deionized water, then add them to a hydrothermal reactor, rapidly heat to 200°C, and react at this temperature for 60 min, then slowly cool to room temperature to obtain a suspension of carbon quantum dots.

[0153] (2) Dissolve 135.87 parts by weight of adipic acid and 100 parts by weight of pentanediamine in 100 parts of deionized water, then add 2 parts by weight of silicone oil, 0.5 parts by weight of catalyst (the mass ratio of iron oxide and disodium hydrogen phosphate is 1:1, and they are ground and mixed) and 0.5 parts by weight of antioxidant (antioxidant H3322). After mixing evenly, add it to the reaction vessel containing the suspension of carbon quantum dots. Adjust the pH of the system to 7.2 using pentanediamine. After replacing the air in the vessel with nitrogen, start stirring, set the speed to 80 r / min, and slowly raise the temperature to 210℃ and react at a constant temperature for 3 hours.

[0154] (3) Open the vent valve to release water vapor and unreacted monomers or byproducts (takes 60 min), and control the temperature to slowly rise to 260℃ while restoring the system to normal pressure;

[0155] (4) After the system is restored to normal pressure, vacuum is drawn at a constant temperature of 260℃. The vacuum degree increases by 0.020MPa every 10min until it reaches -0.090MPa. Under this condition, the reaction continues for 5min until the system viscosity reaches 2.2. Then, nitrogen is introduced to restore normal pressure, and the material is discharged, cast into a strip, cooled, and pelletized to obtain antistatic nylon masterbatch.

[0156] The antistatic nylon masterbatch and antistatic nylon composite material prepared in the above embodiments and comparative examples were tested for performance according to the following methods, and the specific results are shown in the table below.

[0157] (1) Relative viscosity of antistatic nylon masterbatch: After drying the antistatic nylon masterbatch at 80℃ for 6 hours, it was dissolved in m-cresol to prepare a dilute solution of 0.01 g / mL. The relative viscosity of the antistatic nylon masterbatch was measured using an IVS400-2 automatic viscometer to characterize the molecular weight of the antistatic nylon masterbatch. The test temperature was 25℃. The capillary was washed twice with m-cresol, and the outflow time of the m-cresol and antistatic nylon masterbatch solutions was measured respectively. The average value of three measurements with an error of less than 0.02 s was taken to calculate the relative viscosity.

[0158] (2) The antistatic nylon composite material was dried in a vacuum oven at 100℃ for 6 hours, and then injection molded using a WZS10 micro injection molding machine. The injection temperature was the melting point of each antistatic nylon composite material +10℃, the mold temperature was 60℃, and the injection pressure was 0.7MPa. Tensile, bending, and impact specimens were injection molded according to GB / T 1040 and GB / T 1842, and then tensile, bending, and impact tests were performed. The tensile and bending properties were determined using an Instron 5567 universal testing machine, with a tensile rate of 5mm / min and a temperature of 25℃; the bending compression rate was 2mm / min, the span was 64, and the temperature was 25℃; the impact test was conducted using an HT50P impact testing machine, with the test mode being a cantilever beam.

[0159] (3) The granules of antistatic nylon composite material were dried in a vacuum oven at 100°C for 6 hours. Then, a WZS10 micro injection molding machine was used to inject circular strips with a diameter of 58 mm and a thickness of 3.5 mm under the processing conditions of barrel temperature +10°C of the melting point of each antistatic nylon composite material, mold temperature of 60°C and injection pressure of 0.7 MPa. The surface resistance was measured in accordance with GB / T 1410.

[0160] Table 1

[0161]

[0162]

[0163] As shown in the table above, this invention prepares carbon quantum dots in situ and controls the materials, reaction temperature, and reaction time to adjust the number of active functional groups on the carbon dot surface. Furthermore, in-situ polymerization of nylon on the carbon dot surface is achieved in a reactor via pH control, successfully preparing an antistatic nylon masterbatch. The degree of polymerization is characterized by the relative viscosity of the antistatic nylon masterbatch; the introduction of a large number of carbon quantum dots did not cause a decrease in relative viscosity. However, as the number of carbon atoms in the dicarboxylic acid increases, the relative viscosity decreases because the chain segment flexibility increases, while the number of hydrogen bonds decreases, resulting in weaker intermolecular interactions in the solution. Moreover, the antistatic nylon masterbatch can be melt-blended with different nylon resins to prepare antistatic nylon composite materials. This not only imparts good antistatic properties to the nylon resin but also solves the dispersibility problem of nano-antistatic agents. Furthermore, the nylon segments on the carbon dot surface, connected by chemical bonds, have good compatibility with other resin matrices, resulting in excellent mechanical properties. Selecting different antistatic nylon masterbatches according to different resins can achieve reinforcing and toughening effects.

[0164] Examples 1-3 show that antistatic nylon masterbatches with different chain lengths can be prepared using different diamines and diacids. As the number of carbon atoms in the monomer increases, the proportion of amide groups decreases, the flexibility of the antistatic nylon masterbatch molecular chain increases, and the intermolecular interaction force decreases. The antistatic nylon 56 composite material prepared by blending it with nylon 56 exhibits enhanced impact resistance, but slightly reduced tensile strength and flexural strength. Under the condition of consistent addition, the surface resistivity of nylon 56 resins prepared using different antistatic nylon masterbatches is almost identical, indicating that different antistatic nylon masterbatches only change the mechanical properties of the material and do not affect its antistatic properties. Analysis of Examples 4-8 shows that this antistatic nylon masterbatch has good application potential for different nylon resins and also exhibits the characteristic that the impact resistance increases with the increase of the nylon carbon chain length in the antistatic nylon masterbatch.

[0165] Compared with Comparative Examples 1-4 and 14, Example 1 revealed that reaction temperature, time, and reaction method are crucial for the preparation of activated carbon quantum dots. Incomplete carbon dot formation, resulting in a large number of unreacted monomers in the subsequent polymerization system, halts some nylon polymerization, leading to lower viscosity. This weakens the interaction between the antistatic nylon masterbatch and the nylon resin, reduces the number of conductive carbon dots, and decreases antistatic performance. Conversely, excessively high temperatures or long reaction times cause some carbon dots to completely carbonize and lose their reactivity, making them difficult to react with nylon and resulting in poor dispersibility. The deactivated carbon dots have a weaker impact on the nylon polymerization reaction, thus slightly decreasing viscosity. When using this nylon masterbatch, the introduction of uneven molecular chains and poorly dispersed carbon dots into the nylon system reduces mechanical properties and increases surface resistance due to the uneven carbon dot distribution.

[0166] As can be seen from the comparison between Example 1 and Comparative Examples 5-6, pH control during the polymerization of antistatic nylon masterbatch is crucial for preparing high-performance antistatic nylon masterbatch. When carbon quantum dots are prepared using citric acid, a certain amount of carboxyl groups are retained on the carbon dot surface. Introducing a large number of carbon quantum dots into the antistatic nylon masterbatch will increase the carboxyl content. Therefore, the amount of diacid should be appropriately adjusted to control the pH of the system. Furthermore, a single carbon dot surface contains multiple carboxyl groups. Insufficient diacid addition will cause the nylon molecular chains to crosslink on the carbon dot surface, affecting molecular weight growth and leading to a decrease in masterbatch viscosity. Excessive diacid addition (i.e., under acidic conditions with pH < 7) will cause an imbalance in the acid-amine ratio, resulting in a significant decrease in mechanical properties, but little impact on antistatic properties.

[0167] As can be seen from the comparison between Example 1 and Comparative Examples 7-8, the combined use of catalysts is key to the successful preparation of high-viscosity antistatic masterbatch. Ferric oxide (Fe3O4) possesses thermomagnetic properties and can rapidly transfer heat to the raw materials at high temperatures, promoting monomer carbonization. Without this catalyst, heat transfer is uneven, some monomers fail to carbonize in time, resulting in incomplete carbon dot formation and the involvement of other monomers in the system, affecting subsequent polymerization. Disodium hydrogen phosphate, on the other hand, is a catalyst that promotes proton exchange and dehydration, accelerating the amidation process and ensuring rapid polymerization even after the introduction of carbon dots, thus increasing viscosity.

[0168] As shown in Examples 1-3 and Comparative Examples 9-10, appropriate antistatic nylon masterbatches should be selected for antistatic modification of different nylon resins. Not only should the influence of the molecular chain length of the antistatic nylon masterbatch on mechanical properties be considered, but also the melting points of the antistatic nylon masterbatch and the nylon resin. In Examples 1-3, the melting point of the antistatic nylon masterbatch is less than or equal to that of nylon 56, which allows for uniform dispersion of the masterbatch in the resin. Due to their similar chemical structures, they have good compatibility and high mechanical properties. The carbon quantum dots act as crosslinking points, resulting in good reliability. However, in Comparative Examples 9-10, when the melting point of the antistatic nylon masterbatch is greater than that of the nylon resin, the masterbatch is difficult to disperse uniformly in the resin, leading to a decrease in strength and a weakening of the antistatic performance.

[0169] Compared with Comparative Example 11, the carbon quantum dots were directly mechanically blended with nylon. Due to the poor compatibility between carbon quantum dots and nylon resin, the dispersion was uneven, which reduced the mechanical properties and weakened the antistatic properties of the prepared nylon composite material.

[0170] Compared with Comparative Example 12, carbon quantum dots prepared using other raw materials have poor compatibility with nylon, resulting in uneven dispersion, which reduces the mechanical properties and weakens the antistatic properties of the prepared nylon composite material.

[0171] Compared with Comparative Example 13, if the temperature is directly raised to 210℃, the carbon quantum dots cannot fully react with nylon, the degree of cross-linking is reduced, and the mechanical properties will be affected. At the same time, the unreacted carbon quantum dots have poor compatibility with nylon resin, resulting in uneven dispersion and weakened antistatic properties.

[0172] In summary, this invention synthesizes carbon quantum dots containing active functional groups in situ and directly polymerizes nylon resin on the surface of carbon quantum dots to prepare antistatic nylon masterbatch, thus solving the problems of dispersion and compatibility of inorganic nanoparticles in nylon resin. Melt blending the antistatic nylon masterbatch with different nylon resins not only imparts good antistatic properties to the nylon resin but also improves its mechanical properties to a certain extent.

[0173] Of course, the present invention may have other embodiments and variations. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and variations according to the present invention, but these corresponding changes and variations should all fall within the protection scope of the claims of the present invention.

Claims

1. A method for preparing an antistatic nylon masterbatch, characterized in that, Includes the following steps: (1) After urea and citric acid are mixed evenly in a solid-solid manner, they are reacted at 200~250℃ for 15~60min in an inert gas atmosphere, then cooled to room temperature, deionized water is added and mixed evenly to obtain a suspension of carbon quantum dots. (2) In an inert gas atmosphere, an aqueous solution of diamine, diacid, catalyst, lubricant and antioxidant is reacted with a suspension of carbon quantum dots at pH 7.0~7.5 and 80~100℃ for 0.5~2h, and then the temperature is raised to 170~220℃ for 1~3h to obtain a carbon quantum dot / polyamide composite prepolymer. (3) The carbon quantum dot / polyamide composite prepolymer is cooled to normal pressure and heated to 230~280℃, then evacuated to vacuum under constant temperature, and the reaction continues until the relative viscosity of the system reaches 2.2~2.

6. After cooling and pelletizing, the antistatic nylon masterbatch is obtained. The catalyst is a mixture of iron(III) oxide and disodium hydrogen phosphate. The mass ratio of the iron(III) oxide to the disodium hydrogen phosphate is 1:1 to 1:

3.

2. The method for preparing antistatic nylon masterbatch as described in claim 1, characterized in that, By weight, the urea is 10-20 parts, the citric acid is 10-20 parts, the diamine is 100 parts, the diacid is 90-200 parts, the lubricant is 2-5 parts, the catalyst is 0.5-1 part, and the antioxidant is 0.5-1 part.

3. The method for preparing antistatic nylon masterbatch as described in claim 1, characterized in that, In step (2), the pH is adjusted using the diamine or the dicarboxylic acid.

4. The method for preparing antistatic nylon masterbatch as described in claim 1, characterized in that, In step (3), the carbon quantum dot / polyamide composite prepolymer is cooled to atmospheric pressure and heated to 230-280°C within 30-120 minutes; In step (3), the vacuuming rate is (0.01~0.03) MPa / 10min.

5. The method for preparing antistatic nylon masterbatch as described in claim 1, characterized in that, The diamine is selected from any one of pentanediamine, hexanediamine, nonanediamine, decanediamine, and dodecanediamine; The dicarboxylic acid is selected from any one of succinic acid, adipic acid, sebacic acid, and dodecanoic acid; The lubricant is selected from silicone oil and / or stearic acid.

6. An antistatic nylon masterbatch, characterized in that, It is prepared by the method of any one of claims 1-5 for preparing antistatic nylon masterbatch.

7. An antistatic nylon composite material, characterized in that, The method includes the antistatic nylon masterbatch and nylon resin prepared by the method of preparing antistatic nylon masterbatch according to any one of claims 1-5, wherein the melting point of the antistatic nylon masterbatch is lower than the melting point of the nylon resin.

8. The antistatic nylon composite material as described in claim 7, characterized in that, The nylon resin is selected from any one of nylon 56, nylon 66, nylon 12 and nylon 6.

9. The antistatic nylon composite material as described in claim 7, characterized in that, By weight, the antistatic nylon masterbatch comprises 10-40 parts and the nylon resin comprises 60-90 parts.

10. A method for preparing the antistatic nylon composite material according to any one of claims 7-9, characterized in that, The process includes the following steps: mixing the antistatic nylon masterbatch with the nylon resin, and then performing melt blending extrusion using a screw extruder, wherein the screw temperature is 170~280℃ and the rotation speed is 40~60 r / min.

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