Reinforced modified PET composite material and preparation method thereof

Abstract

The invention relates to the field of high polymer materials, and discloses a reinforced modified PET composite material and a preparation method thereof.The composite material comprises modified PET, modified montmorillonite, an epoxy chain amplification agent and the like, the modified PET is prepared from terephthalic acid, ethylene glycol and a flame-retardant modifier through copolymerization, and the flame-retardant modifier is prepared from DOPO and 4, 4 '-dihydroxy-9-oxa-10-phosphaphenanthrene-10-oxide. Reacting with 4, 4 '-dihydroxybenzophenone, and then carrying out nucleophilic ring-opening reaction with ethylene carbonate. The modified montmorillonite is prepared by performing montmorillonite double-bond functionalization treatment on the modified montmorillonite through a silane coupling agent and then compounding with ZIF-8 particles of which the surfaces are grafted with the modified silane coupling agent; the modified silane coupling agent is prepared by simultaneously reacting an antibacterial monomer, 3-(methacryloyloxy) propyl trimethoxy silane and phenyl tri (dimethyl siloxane) silane, wherein the antibacterial monomer and the 3-(methacryloyloxy) propyl trimethoxy silane are generated by reacting 2-(2-thiobenzothiazole) ethanol with isocyano ethyl methacrylate; the reinforced modified PET composite material prepared by the invention has excellent mechanical property, flame retardant property, heat resistance and antibacterial property.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer materials, and particularly relates to a reinforced modified PET composite material and a preparation method thereof. Background Art

[0002] PET (polyethylene terephthalate) is a polymer made from the polycondensation of ethylene glycol and terephthalic acid. As an important thermoplastic material, PET is widely used in plastics, films, and fibers due to its excellent physical and chemical properties, including high strength, fatigue resistance, aging resistance, and corrosion resistance. However, PET has a low limiting oxygen index and is easily flammable. Furthermore, combustion produces a large amount of molten droplets, which can spread and cause fires.

[0003] Common methods for flame-retardant modification of PET in the prior art include blending and copolymerization. Blending modification is simple to operate, but has the disadvantage of poor compatibility between the flame retardant and the polyester matrix, and the flame retardant effect is not long-lasting. Copolymerization modification improves the flame retardant properties of the polyester by changing its structure. The modified copolyester has long-lasting flame retardancy. However, the phosphorus element in the existing copolymerized modified polyester structure is located on the main chain of the PET molecule. When the polyester is burned at high temperature, the phosphoric acid produced by the shedding of the phosphorus element and its polymer cover the polyester surface to form a dense carbon layer, which can isolate the combustible material from contact with oxygen, thereby hindering the combustion of the polyester. However, the shedding of the phosphorus element on the main chain can cause the PET molecular chain to be destroyed, causing serious melting droplets, and there is a hidden danger of causing secondary fires. In addition, existing PET composite materials have defects such as insufficient antibacterial properties and poor mechanical properties, and need to be modified to enhance their required properties. Summary of the Invention

[0004] In order to solve the deficiencies mentioned in the above background technology, the purpose of the present invention is to provide a reinforced modified PET composite material and a preparation method thereof, wherein the prepared reinforced modified PET composite material has excellent mechanical properties, flame retardant properties, heat resistance and antibacterial properties.

[0005] The purpose of the present invention can be achieved through the following technical solutions:

[0006] A reinforced modified PET composite material comprises the following components in parts by weight: 100 parts of modified PET, 1 to 5 parts of modified montmorillonite, 0.5 to 1.5 parts of an epoxy chain extender, 0.1 to 0.5 parts of a lubricant, and 0.01 to 0.1 parts of an antioxidant;

[0007] The modified PET is prepared by copolymerization of terephthalic acid, ethylene glycol and a flame retardant modifier, wherein the flame retardant modifier is prepared by a nucleophilic ring-opening reaction between a DOPO derivative generated by the reaction of two DOPO molecules with the carbonyl group of 4,4'-dihydroxybenzophenone and ethylene carbonate;

[0008] The modified montmorillonite is prepared by subjecting the montmorillonite to double-bond functionalization treatment with 3-(methacryloyloxy)propyltrimethoxysilane, and then undergoing a hydrosilylation reaction with ZIF-8 particles with a surface-grafted modified silane coupling agent. The ZIF-8 is a metal-organic framework material formed by the coordination of zinc ions and 2-methylimidazole. The modified silane coupling agent is prepared by subjecting 2-(2-thiobenzothiazole)ethanol to a nucleophilic addition reaction with isocyanoethyl methacrylate to generate an antibacterial monomer, and then the antibacterial monomer and 3-(methacryloyloxy)propyltrimethoxysilane are simultaneously subjected to a hydrosilylation reaction with phenyltris(dimethylsiloxy)silane to prepare the modified silane coupling agent.

[0009] Preferably, the epoxy chain extender is one or more combinations of ADR-4380, ADR-4400, ADR-4468, and epoxy-2021P; the lubricant is one or more combinations of stearic acid, polyethylene wax, oxidized polyethylene wax, and paraffin; and the antioxidant is one of antioxidant 1010, antioxidant 168, and antioxidant 1076.

[0010] Preferably, the preparation method of the modified PET comprises the following steps:

[0011] A. DOPO and 4,4'-dihydroxybenzophenone are placed in a reactor, heated to 180-190°C and stirred for reaction for 2.5-3 hours, then cooled to 100-110°C, and toluene solvent is added dropwise while stirring. After the addition is complete, the mixture is quickly filtered and washed. The crude product is then dissolved in boiling N,N-dimethylacetamide under a nitrogen atmosphere, and the hot solution is filtered, precipitated with tetrahydrofuran and diethyl ether, filtered, recrystallized, and dried to prepare a DOPO derivative.

[0012] B. Place a DOPO derivative, ethylene carbonate, and potassium iodide catalyst in a reactor, add N,N-dimethylacetamide solvent, and heat to 155-170° C. under a nitrogen atmosphere while stirring. Continue the reaction for 7-9 hours. After the reaction is complete, cool to room temperature, filter, wash, and dry to obtain a flame retardant modifier.

[0013] C. Terephthalic acid, ethylene glycol, antimony trioxide catalyst, anhydrous sodium acetate and flame retardant modifier are added to a polymerization reactor to carry out esterification and polycondensation reactions. After the reaction is completed, a small amount of nitrogen is introduced to extrude the product during the discharge, and the modified PET is prepared by water cooling, pelletizing and drying.

[0014] Preferably, the molar ratio of DOPO to 4,4'-dihydroxybenzophenone in step A is 2-2.05:1; and the molar ratio of DOPO derivative to ethylene carbonate in step B is 2.95-3.1:1.

[0015] Preferably, the mass fraction of the flame retardant modifier in step C is 3 to 5.5%.

[0016] Preferably, the specific operating steps of the esterification stage in step C are: after filling the kettle with nitrogen and exhausting, maintain the pressure in the kettle at 0.2 MPa, set the stirring speed to 35 r / min, maintain the temperature in the kettle at 220-230° C., and react in the esterification stage for 2.5-3.5 hours. When the pressure in the kettle and the temperature at the top of the distillation column rise, release the pressure through the esterification valve and collect the esterified water. When the temperature at the top of the distillation column rises as the reaction proceeds and then drops below 100° C., and the esterified water output reaches more than 90% of the theoretical value, the esterification stage ends.

[0017] Preferably, the specific operating steps of the polycondensation stage in step C are: maintaining the temperature in the kettle at 265-275°C, setting the stirring speed to 60r / min, turning on the vacuum pump, and adjusting the valve so that the vacuum degree in the kettle slowly drops to below 100Pa within 30min, and the polycondensation stage reacts for 3-4h.

[0018] Preferably, the preparation method of the modified montmorillonite comprises the following steps:

[0019] (1) 2-(2-benzothiazole sulfide)ethanol, isocyanoethyl methacrylate, and dibutyltin dilaurate are placed in a reactor, dichloromethane is added, and the mixture is stirred at 35-45° C. for 10-12 hours. After the reaction is completed, the solvent is removed by rotary evaporation, and the unreacted product is removed by washing with ether. Finally, the mixture is vacuum dried to prepare an antibacterial monomer.

[0020] (2) Phenyl tris(dimethylsiloxy)silane, antibacterial monomer and 3-(methacryloyloxy)propyltrimethoxysilane are placed in a reactor, toluene solvent is added, the temperature is raised to 80-90° C. under a nitrogen atmosphere, Custer catalyst is added and stirred for reaction for 5-8 hours, and after the reaction is completed, the solvent is removed by rotary evaporation to prepare a modified silane coupling agent;

[0021] (3) 2-Methylimidazole was dissolved in methanol, a modified silane coupling agent was added, and the mixture was stirred at 50-60° C. for 2-3 h. Zinc nitrate hexahydrate was then dissolved in methanol and added to the reaction system. The mixture was stirred at 35-40° C. for 2-3 h. After the reaction was completed, the mixture was centrifuged, washed, and dried to prepare a modified metal-organic framework material.

[0022] (4) The montmorillonite was ultrasonically dispersed in deionized water and anhydrous ethanol, and the pH value of the system was adjusted to 3-4 using hydrochloric acid. The temperature was then raised to 75-90°C, 3-(methacryloyloxy)propyltrimethoxysilane was added, and the mixture was stirred for 3-6 hours. After the reaction was completed, the mixture was filtered, washed, and dried to prepare the double-bonded montmorillonite.

[0023] (5) The double-bonded montmorillonite and the modified metal-organic framework material were ultrasonically dispersed in xylene, and the temperature was raised to 95-110°C under a nitrogen atmosphere. Then, the Custer catalyst was added and stirred for 6-8 hours. After the reaction was completed, the modified montmorillonite was prepared by filtration, washing, and drying.

[0024] Preferably, in step (2), the molar ratio of phenyltris(dimethylsiloxy)silane, antibacterial monomer and 3-(methacryloyloxy)propyltrimethoxysilane is 1:1-1.2:1-1.2.

[0025] A method for preparing a reinforced modified PET composite material comprises the following steps: weighing raw materials in parts by weight, uniformly mixing modified montmorillonite, an epoxy chain extender, a lubricant, an antioxidant and the dried modified PET in a high-speed mixer, then melt-extruding the mixture at 180-240° C. using a twin-screw extruder, followed by water cooling and granulation to obtain the reinforced modified PET composite material.

[0026] Beneficial effects of the present invention:

[0027] The present invention utilizes modified PET, modified montmorillonite, epoxy chain extenders and additives as raw materials. The epoxy chain extenders react with some end groups and degradation chain scission sites of PET during melt blending to avoid excessive molecular weight loss. The addition of modified PET and modified montmorillonite gives the material excellent mechanical properties, flame retardant properties, heat resistance and antibacterial properties. The present invention utilizes two DOPO molecules and the carbonyl group in 4,4'-dihydroxybenzophenone to sequentially undergo nucleophilic addition and nucleophilic substitution reactions to prepare a flame retardant DOPO derivative containing double DOPO. Then, the DOPO derivative and ethylene carbonate are used as raw materials to prepare a flame retardant modifier containing a phosphorus element grafted on the side chain. The phenolic hydroxyl group in the DOPO derivative structure reacts with the ethylene carbonate to form an alcoholic hydroxyl group. Terephthalic acid, ethylene glycol, and the flame retardant modifier are used as raw materials to prepare a modified PET having a side chain containing a phosphorus element and having both good heat resistance and flame retardancy through copolymerization. The side chain phosphorus element is prevented from falling off during combustion of the polyester, thereby preventing the regularity of the PET main chain structure from being affected. The flame retardancy of the PET is improved while molten dripping is reduced, thereby imparting excellent flame retardancy and a UL-94 rating to the PET.

[0028] The present invention utilizes the hydroxyl group in 2-(2-benzothiazole sulfide) ethanol and the isocyanate group in isocyanoethyl methacrylate to undergo a nucleophilic addition reaction to prepare an antibacterial monomer containing benzothiazole, then utilizes the double bond introduced in the antibacterial monomer and 3-(methacryloyloxy)propyltrimethoxysilane to simultaneously undergo a silylation reaction with phenyltris(dimethylsiloxy)silane to prepare a modified silane coupling agent with one remaining silylation bond, then utilizes the silanol group in the modified silane coupling agent to undergo a condensation reaction with the formed ZIF-8 to prepare a modified metal-organic framework material, thereby bonding the antibacterial monomer to the surface of ZIF-8 through a strong chemical bond, thereby imparting long-lasting antibacterial properties to the material, and finally utilizes the montmorillonite double-bond modified by 3-(methacryloyloxy)propyltrimethoxysilane to react with the modified metal-organic framework. The remaining ungrafted silicon-hydrogen bonds in the material undergo a silicon-hydrogen addition reaction to prepare modified montmorillonite, thereby loading ZIF-8 between the montmorillonite layers, increasing the interlayer spacing of the montmorillonite, and making the modified montmorillonite relatively evenly dispersed in the matrix material, which is beneficial to the full development of its mechanical properties, and is beneficial to the layered structure of montmorillonite and ZIF-8 to synergistically extend the thermal decomposition path, thereby improving the heat resistance of the material. At the same time, the multiple silicon-oxygen bonds introduced into the modified montmorillonite structure also improve the heat resistance of the material to a certain extent. In addition, montmorillonite and ZIF-8 can not only provide surface active sites to promote the movement of PET molecular chains, but also have certain nucleation and reinforcement effects, thereby simultaneously improving the melt fluidity and mechanical strength of the product in a reactive extrusion environment of 180-240°C, and are suitable for various molding processes such as injection molding, extrusion and blow molding.

[0029] DETAILED DESCRIPTION

[0030] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0031] Example 1 A method for preparing modified PET comprises the following steps:

[0032] A. 21.6 g of DOPO and 10.7 g of 4,4'-dihydroxybenzophenone were placed in a reactor, heated to 190°C and stirred for reaction for 3 h, then cooled to 100°C, and 80 mL of toluene solvent was added dropwise while stirring. After the addition was complete, the mixture was quickly filtered and washed. The crude product was then dissolved in boiling N,N-dimethylacetamide under a nitrogen atmosphere. The hot solution was then filtered, precipitated with tetrahydrofuran and diethyl ether, filtered, recrystallized, and dried to prepare a DOPO derivative.

[0033] B. 31.4 g of a DOPO derivative (Mr = 628.56), 13.2 g of ethylene carbonate, and 0.2 g of a potassium iodide catalyst were placed in a reactor, 100 mL of N,N-dimethylacetamide solvent was added, and the mixture was heated to 160° C. under a nitrogen atmosphere while stirring. The reaction was continued for 8 h. After the reaction was completed, the mixture was cooled to room temperature, filtered, washed, and dried to prepare a flame retardant modifier.

[0034] C. Take 4 mol of terephthalic acid, 5.6 mol of ethylene glycol, 0.02% of antimony trioxide catalyst, 0.02% of anhydrous sodium acetate and 5% of flame retardant modifier and add them into the polymerization reactor. Fill the reactor with nitrogen and exhaust it to maintain the pressure in the reactor at 0.2 MPa. Set the stirring speed to 35 r / min and the temperature in the reactor at 220°C. The esterification stage reacts for 3 hours. When the pressure in the reactor and the temperature at the top of the fractionating column rise, release the pressure through the esterification valve and collect the esterified water. When the pressure in the reactor and the temperature at the top of the fractionating column rise, The temperature rises as the reaction proceeds and then drops to below 100°C, and when the esterification water output reaches more than 90% of the theoretical value, the esterification stage ends and enters the polycondensation stage. The temperature in the kettle is maintained at 270°C, the stirring speed is set to 60r / min, the vacuum pump is turned on, and the valve is adjusted so that the vacuum degree in the kettle slowly drops to below 100Pa within 30 minutes. The polycondensation stage reacts for 4 hours. After the reaction is completed, the material is ready for discharge. A small amount of nitrogen is introduced during discharge to extrude the product. The modified PET is prepared by water cooling, pelletizing, and drying.

[0035] Example 2 A method for preparing modified montmorillonite comprises the following steps:

[0036] (1) 10.5 g of 2-(2-benzothiazole sulfide)ethanol, 7.8 g of isocyanoethyl methacrylate, and two drops of dibutyltin dilaurate were placed in a reactor, 60 mL of dichloromethane was added, and the mixture was stirred at 40° C. for 12 h. After the reaction was completed, the solvent was removed by rotary evaporation, and the unreacted product was removed by washing with ether. Finally, the mixture was vacuum dried to prepare an antibacterial monomer.

[0037] (2) 6.6 g of phenyltris(dimethylsiloxy)silane, 7.3 g of antibacterial monomer (Mr=366.45) and 5 g of 3-(methacryloyloxy)propyltrimethoxysilane were placed in a reactor, 50 mL of toluene solvent was added, the temperature was raised to 90° C. under a nitrogen atmosphere, 0.2 g of Custer catalyst was added and stirred for 7 h, and after the reaction was completed, the solvent was removed by rotary evaporation to prepare a modified silane coupling agent;

[0038] (3) 4.8 g of 2-methylimidazole was dissolved in 100 mL of methanol, 3.2 g of modified silane coupling agent was added, and the mixture was stirred at 55 ° C for 3 h. Then, 2.8 g of zinc nitrate hexahydrate was dissolved in 30 mL of methanol and added to the reaction system, and the mixture was stirred at 40 ° C for 2 h. After the reaction was completed, the mixture was centrifuged, washed, and dried to prepare a modified metal-organic framework material;

[0039] (4) 5 g of montmorillonite was ultrasonically dispersed in 10 mL of deionized water and 90 mL of anhydrous ethanol. The pH value of the system was adjusted to 4 using hydrochloric acid. The temperature was then raised to 85°C, and 0.7 g of 3-(methacryloyloxy)propyltrimethoxysilane was added. The mixture was stirred for 5 h. After the reaction was completed, the mixture was filtered, washed, and dried to obtain double-bonded montmorillonite.

[0040] (5) Take 5 g of double-bonded montmorillonite and 5 g of modified metal-organic framework material and ultrasonically disperse them in 250 mL of xylene. Heat the mixture to 100 °C under a nitrogen atmosphere, then add 0.2 g of Castel catalyst and stir the reaction for 8 h. After the reaction is completed, filter, wash and dry to prepare modified montmorillonite.

[0041] Example 3 A reinforced modified PET composite material comprises the following components in parts by weight: 100 parts of the modified PET prepared in Example 1, 1.5 parts of the modified montmorillonite prepared in Example 2, 0.7 parts of an epoxy chain extender ADR-4380, 0.1 parts of a lubricant polyethylene wax, and 0.02 parts of an antioxidant 1010.

[0042] The preparation method of the above-mentioned enhanced modified PET composite material comprises the following steps:

[0043] The raw materials were weighed according to weight, and the modified montmorillonite, epoxy chain extender, lubricant, antioxidant and the dried modified PET were placed in a high-speed mixer and uniformly mixed. Then, the mixture was melt-extruded at 220°C using a twin-screw extruder, and then water-cooled and granulated to prepare a reinforced modified PET composite material.

[0044] Example 4 A reinforced modified PET composite material comprises the following components in parts by weight: 100 parts of the modified PET prepared in Example 1, 3 parts of the modified montmorillonite prepared in Example 2, 1.1 parts of an epoxy chain extender ADR-4380, 0.2 parts of a lubricant polyethylene wax, and 0.04 parts of an antioxidant 1010.

[0045] The preparation method of the reinforced modified PET composite material is the same as that in Example 3.

[0046] Example 5 A reinforced modified PET composite material comprises the following components in parts by weight: 100 parts of the modified PET prepared in Example 1, 4.6 parts of the modified montmorillonite prepared in Example 2, 1.3 parts of an epoxy chain extender ADR-4380, 0.4 parts of a lubricant polyethylene wax, and 0.08 parts of an antioxidant 1010.

[0047] The preparation method of the reinforced modified PET composite material is the same as that in Example 3.

[0048] Comparative Example 1 A method for preparing modified montmorillonite comprises the following steps:

[0049] (1) 6.6 g of phenyltris(dimethylsiloxy)silane and 5 g of 3-(methacryloyloxy)propyltrimethoxysilane were placed in a reactor, 50 mL of toluene solvent was added, the temperature was raised to 90° C. under a nitrogen atmosphere, 0.2 g of Custer catalyst was added, and the mixture was stirred and reacted for 7 h. After the reaction was completed, the solvent was removed by rotary evaporation to prepare a modified silane coupling agent;

[0050] (2) 4.8 g of 2-methylimidazole was dissolved in 100 mL of methanol, 3.2 g of a modified silane coupling agent was added, and the mixture was stirred at 55° C. for 3 h. Then, 2.8 g of zinc nitrate hexahydrate was dissolved in 30 mL of methanol and added to the reaction system, and the mixture was stirred at 40° C. for 2 h. After the reaction was completed, the mixture was centrifuged, washed, and dried to prepare a modified metal-organic framework material.

[0051] (3) 5 g of montmorillonite was ultrasonically dispersed in 10 mL of deionized water and 90 mL of anhydrous ethanol. The pH value of the system was adjusted to 4 using hydrochloric acid. The temperature was then raised to 85°C, and 0.7 g of 3-(methacryloyloxy)propyltrimethoxysilane was added. The mixture was stirred for 5 h. After the reaction was completed, the mixture was filtered, washed, and dried to obtain double-bonded montmorillonite.

[0052] (4) Take 5 g of double-bonded montmorillonite and 5 g of modified metal-organic framework material and ultrasonically disperse them in 250 mL of xylene. Heat the mixture to 100 °C under a nitrogen atmosphere, then add 0.2 g of Castel catalyst and stir the mixture for 8 h. After the reaction is completed, filter, wash and dry the mixture to obtain modified montmorillonite.

[0053] Comparative Example 2: A reinforced modified PET composite material, comprising the following components in parts by weight: 100 parts of commercially available PET (produced by Yizheng Xiangheng Polyester Technology Co., Ltd.), 4.6 parts of modified montmorillonite prepared in Example 2, 1.3 parts of epoxy chain extender ADR-4380, 0.4 parts of lubricant polyethylene wax, and 0.08 parts of antioxidant 1010.

[0054] The preparation method of the reinforced modified PET composite material is the same as that in Example 3.

[0055] Comparative Example 3 A reinforced modified PET composite material comprises the following components in parts by weight: 100 parts of the modified PET prepared in Example 1, 4.6 parts of the modified montmorillonite prepared in Comparative Example 1, 1.3 parts of an epoxy chain extender ADR-4380, 0.4 parts of a lubricant polyethylene wax, and 0.08 parts of an antioxidant 1010.

[0056] The preparation method of the reinforced modified PET composite material is the same as that in Example 3.

[0057] Comparative Example 4: A reinforced modified PET composite material comprises the following components in parts by weight: 100 parts of the modified PET prepared in Example 1, 2.3 parts of the modified metal-organic framework material prepared in Example 2, 2.3 parts of montmorillonite, 1.3 parts of an epoxy chain extender ADR-4380, 0.4 parts of a lubricant polyethylene wax, and 0.08 parts of an antioxidant 1010.

[0058] The preparation method of the reinforced modified PET composite material is the same as that in Example 3.

[0059] Comparative Example 5: A reinforced modified PET composite material comprising the following components in parts by weight: 100 parts of the modified PET prepared in Example 1, 2.3 parts of ZIF-8, 2.3 parts of montmorillonite, 1.3 parts of an epoxy chain extender ADR-4380, 0.4 parts of a lubricant polyethylene wax, and 0.08 parts of an antioxidant 1010;

[0060] The preparation method of ZIF-8 includes the following steps: dissolving 3 g of zinc nitrate hexahydrate and 6.6 g of 2-methylimidazole in 140 mL of anhydrous methanol respectively, adding the methanol solution of 2-methylimidazole dropwise to the methanol solution of zinc nitrate hexahydrate, stirring the mixture continuously under magnetic stirring for 24 hours and then centrifuging, washing the solid three times with 30 mL of methanol and then vacuum drying at 80°C for 24 hours to prepare ZIF-8.

[0061] The preparation method of the reinforced modified PET composite material is the same as that in Example 3.

[0062] Performance testing

[0063] The reinforced modified PET composite materials prepared in Examples 3-5 and Comparative Examples 2-5 were injection molded into standard test specimens and performance tests were performed:

[0064] (1) Mechanical properties test: The notched impact strength of simply supported beams was tested according to GB / T 1043.1-2008, with the dimensions of 80 mm × 10 mm × 4 mm and a V-notch depth of 2 mm. The tensile properties were tested according to GB / T 1040.1-2025, with the dumbbell-shaped specimens of 115 mm × 10 mm × 4 mm and a tensile speed of 20 mm / min. The bending properties were tested according to GB / T 1043.1-2008, with the dimensions of 80 mm × 10 mm × 4 mm and a bending speed of 5 mm / min. The data results are shown in Table 1.

[0065] (2) Flame retardant performance test: The limiting oxygen index (LOI) test was performed using an oxygen index analyzer in accordance with GB / T 2406.2-2009; the vertical combustion (UL-94) test was performed using a vertical combustion apparatus in accordance with GB / T 2408-2021. The data results are shown in Table 1.

[0066] (3) Heat resistance test: The samples were analyzed using a thermogravimetric analyzer (TGA). The test was carried out in a nitrogen environment with a nitrogen flow rate of 40 mL / min, a heating rate of 10 °C / min, and a heating range of 25 to 600 °C. The data results are shown in Table 1.

[0067] (4) Antibacterial performance test: The sample was injection molded into 60mm×60mm×4mm, and then cut into test pieces with a length and width of 50mm. The test pieces were placed in a culture dish. Each test piece was dripped with an equal amount of bacterial culture solution with the same experimental bacterial species concentration. It was covered with a polyethylene film with a length and width of 40mm to ensure that the bacterial culture solution was in close contact with the test piece. The culture dish was placed in an incubator for constant temperature culture. After 24 hours, it was taken out and placed in an equal amount of elution solution for full elution. Finally, the culture dishes were separated. A certain amount of eluate was added dropwise to a solid nutrient agar plate and evenly spread with a spreader. The coated culture dish was inverted in a constant temperature incubator and cultured at 37°C for 24 hours. The number of bacterial colonies on each culture dish was read with a colony counter. The antibacterial rate was calculated as follows: R = (Nc-Ns) / Nc×100%, where R is the antibacterial rate, %; Nc is the number of colonies recovered from the blank sample, cfu / plate; Ns is the number of colonies recovered from the antibacterial sample, cfu / plate. The data results are shown in Table 1.

[0068] Table 1 Test results of sample performance

[0069]

[0070]

[0071] It can be seen from the data in Table 1 that the reinforced modified PET composite materials prepared in Examples 3-5 of the present invention have excellent mechanical properties, flame retardant properties, heat resistance and antibacterial properties. Among them, commercially available PET is used in Comparative Example 2, and its measured limiting oxygen index and UL-94 grade are worse than those of Examples 3-5, indicating that the grafting of the flame retardant modifier improves the flame retardant properties of the material. The modified montmorillonite added in Comparative Example 3 is not grafted with an antibacterial monomer, and its measured antibacterial rate of Escherichia coli and antibacterial rate of Staphylococcus aureus are lower than those of Examples 3-5, indicating that the grafting of the antibacterial monomer is beneficial to improving the antibacterial properties of the material. In Comparative Example 4, the modified metal-organic framework material and montmorillonite are simply mixed, and its measured mechanical properties and initial thermal decomposition temperature are lower than those of Examples 3-5. The possible reason is that the agglomeration of nanoparticles leads to a decrease in mechanical properties and heat resistance. In Comparative Example 5, ZIF-8 and montmorillonite are simply mixed, and its measured mechanical properties, initial thermal decomposition temperature, antibacterial rate of Escherichia coli and antibacterial rate of Staphylococcus aureus are lower than those of Examples 3-5, indicating that the addition of modified montmorillonite is beneficial to improving the mechanical properties, heat resistance and antibacterial properties of the material.

[0072] Throughout this specification, references to terms such as "one embodiment," "example," or "specific example" indicate that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, schematic representations of these terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0073] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention, and such changes and modifications fall within the scope of the invention as claimed.

Claims

1. A reinforced modified PET composite material, characterized in that: The invention comprises the following components in parts by weight: 100 parts of modified PET, 1 to 5 parts of modified montmorillonite, 0.5 to 1.5 parts of epoxy chain extender, 0.1 to 0.5 parts of lubricant, and 0.01 to 0.1 parts of antioxidant; The modified PET is prepared by copolymerization of terephthalic acid, ethylene glycol and a flame retardant modifier, wherein the flame retardant modifier is prepared by a nucleophilic ring-opening reaction between a DOPO derivative generated by the reaction of two DOPO molecules with the carbonyl group of 4,4'-dihydroxybenzophenone and ethylene carbonate; The modified montmorillonite is prepared by subjecting the montmorillonite to double-bond functionalization treatment with 3-(methacryloyloxy)propyltrimethoxysilane, and then undergoing a hydrosilylation reaction with ZIF-8 particles with a surface-grafted modified silane coupling agent. The ZIF-8 is a metal-organic framework material formed by the coordination of zinc ions and 2-methylimidazole. The modified silane coupling agent is prepared by subjecting 2-(2-thiobenzothiazole)ethanol to a nucleophilic addition reaction with isocyanoethyl methacrylate to generate an antibacterial monomer, and then the antibacterial monomer and 3-(methacryloyloxy)propyltrimethoxysilane are simultaneously subjected to a hydrosilylation reaction with phenyltris(dimethylsiloxy)silane to prepare the modified silane coupling agent.

2. The reinforced modified PET composite material according to claim 1, characterized in that The epoxy chain extender is one or more combinations of ADR-4380, ADR-4400, ADR-4468, and epoxy-2021P; the lubricant is one or more combinations of stearic acid, polyethylene wax, oxidized polyethylene wax, and paraffin; and the antioxidant is one of antioxidant 1010, antioxidant 168, and antioxidant 1076.

3. The reinforced modified PET composite material according to claim 1, characterized in that The preparation method of the modified PET comprises the following steps: A. DOPO and 4,4'-dihydroxybenzophenone are placed in a reactor, heated to 180-190°C and stirred for reaction for 2.5-3 hours, then cooled to 100-110°C, and toluene solvent is added dropwise while stirring. After the addition is complete, the mixture is quickly filtered and washed. The crude product is then dissolved in boiling N,N-dimethylacetamide under a nitrogen atmosphere, and the hot solution is filtered, precipitated with tetrahydrofuran and diethyl ether, filtered, recrystallized, and dried to prepare a DOPO derivative. B. Place a DOPO derivative, ethylene carbonate, and potassium iodide catalyst in a reactor, add N,N-dimethylacetamide solvent, and heat to 155-170° C. under a nitrogen atmosphere while stirring. Continue the reaction for 7-9 hours. After the reaction is complete, cool to room temperature, filter, wash, and dry to obtain a flame retardant modifier. C. Terephthalic acid, ethylene glycol, antimony trioxide catalyst, anhydrous sodium acetate and flame retardant modifier are added to a polymerization reactor to carry out esterification and polycondensation reactions. After the reaction is completed, a small amount of nitrogen is introduced to extrude the product during the discharge, and the modified PET is prepared by water cooling, pelletizing and drying.

4. The reinforced modified PET composite material according to claim 3, characterized in that The molar ratio of DOPO to 4,4'-dihydroxybenzophenone in step A is 2-2.05:1; and the molar ratio of DOPO derivative to ethylene carbonate in step B is 2.95-3.1:

1.

5. The reinforced modified PET composite material according to claim 3, characterized in that: The mass fraction of the flame retardant modifier in step C is 3 to 5.5%.

6. The reinforced modified PET composite material according to claim 3, characterized in that: The specific operating steps of the esterification stage in step C are as follows: nitrogen is charged into the kettle and then exhausted to maintain the pressure in the kettle at 0.2 MPa, the stirring speed is set to 35 r / min, the temperature in the kettle is maintained at 220-230° C., the esterification stage is reacted for 2.5-3.5 hours, when the pressure in the kettle and the temperature at the top of the distillation column rise, the pressure is released through the esterification valve and the esterified water is collected, and when the temperature at the top of the distillation column rises as the reaction proceeds and then drops below 100° C. and the esterified water output reaches more than 90% of the theoretical value, the esterification stage is terminated.

7. The reinforced modified PET composite material according to claim 3, characterized in that: The specific operating steps of the polycondensation stage in step C are as follows: maintaining the temperature in the kettle at 265-275° C., setting the stirring speed to 60 r / min, turning on the vacuum pump, and adjusting the valve so that the vacuum degree in the kettle slowly drops to below 100 Pa within 30 minutes, and reacting in the polycondensation stage for 3-4 hours.

8. The reinforced modified PET composite material according to claim 1, characterized in that: The preparation method of the modified montmorillonite comprises the following steps: (1) 2-(2-benzothiazole sulfide)ethanol, isocyanoethyl methacrylate, and dibutyltin dilaurate are placed in a reactor, dichloromethane is added, and the mixture is stirred at 35-45° C. for 10-12 hours. After the reaction is completed, the solvent is removed by rotary evaporation, and the unreacted product is removed by washing with ether. Finally, the mixture is vacuum dried to prepare an antibacterial monomer. (2) Phenyl tris(dimethylsiloxy)silane, antibacterial monomer and 3-(methacryloyloxy)propyltrimethoxysilane are placed in a reactor, toluene solvent is added, the temperature is raised to 80-90° C. under a nitrogen atmosphere, Custer catalyst is added and stirred for reaction for 5-8 hours, and after the reaction is completed, the solvent is removed by rotary evaporation to prepare a modified silane coupling agent; (3) 2-Methylimidazole was dissolved in methanol, a modified silane coupling agent was added, and the mixture was stirred at 50-60° C. for 2-3 h. Zinc nitrate hexahydrate was then dissolved in methanol and added to the reaction system. The mixture was stirred at 35-40° C. for 2-3 h. After the reaction was completed, the mixture was centrifuged, washed, and dried to prepare a modified metal-organic framework material. (4) The montmorillonite was ultrasonically dispersed in deionized water and anhydrous ethanol, and the pH value of the system was adjusted to 3-4 using hydrochloric acid. The temperature was then raised to 75-90°C, 3-(methacryloyloxy)propyltrimethoxysilane was added, and the mixture was stirred for 3-6 hours. After the reaction was completed, the mixture was filtered, washed, and dried to prepare the double-bonded montmorillonite. (5) The double-bonded montmorillonite and the modified metal-organic framework material were ultrasonically dispersed in xylene, and the temperature was raised to 95-110°C under a nitrogen atmosphere. Then, the Custer catalyst was added and stirred for 6-8 hours. After the reaction was completed, the modified montmorillonite was prepared by filtration, washing, and drying.

9. The reinforced modified PET composite material according to claim 8, characterized in that: In the step (2), the molar ratio of phenyltris(dimethylsiloxy)silane, antibacterial monomer and 3-(methacryloyloxy)propyltrimethoxysilane is 1:1-1.2:1-1.

2.

10. A method for preparing the reinforced modified PET composite material according to any one of claims 1 to 9, characterized in that: The method comprises the following steps: weighing raw materials in parts by weight, placing modified montmorillonite, epoxy chain extender, lubricant, antioxidant and dried modified PET in a high-speed mixer and uniformly mixing them, then using a twin-screw extruder to melt-extrude at 180-240° C., followed by water cooling and granulation to prepare a reinforced modified PET composite material.

Images