A kind of high temperature resistant flame retardant PET plastic particles and preparation method thereof

Abstract

The invention discloses a kind of high temperature resistant flame retardant PET plastic granules and preparation method thereof, belong to the technical field of polymer materials, including the following raw materials: 90-100 parts by weight of PET resin, 8-13 parts by weight of modified flame retardant, 0.3-0.6 parts by weight of defoamer, 0.2-0.8 parts by weight of plasticizer, 1-2 parts by weight of antioxidant. The present invention takes PET resin as base material, improves the flame retardant performance of PET plastic granules by the introduction of modified flame retardant, and the modified flame retardant is substituted by the hydroxyl in the chitosan segment coated with the chlorine atom on the polyphosphazene microsphere and the modified carbon nano surface, not only can effectively avoid the degradation of PET resin in the processing process, improve the tensile strength of PET plastic granules, also be conducive to removing the chlorine atom in the polyphosphazene microsphere structure, avoid producing halogen-containing harmful gases in the processing process and the flame retardant process, reduce the toxicity of the modified flame retardant.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer materials, and in particular relates to high temperature resistant and flame retardant PET plastic particles and a preparation method thereof. Background Art

[0002] Polyethylene terephthalate, abbreviated as PET, is a thermoplastic polyester. Due to its excellent physical, mechanical and chemical properties, it is widely used in synthetic fibers, plastic packaging and engineering plastics. However, PET has a low limiting oxygen index and is a flammable material. When it burns, it produces a large amount of black smoke accompanied by severe dripping, posing a huge threat to people's lives and property safety.

[0003] In the prior art, chitosan is added to improve the flame retardant properties of PET plastic when preparing PET plastic particles. Chitosan, as a natural high molecular sugar, can be used in intumescent flame retardants and has good flame retardant properties. However, there are a large number of hydroxyl groups in the chitosan molecule, which will dehydrate during the processing with the polymer. PET will degrade when it encounters water under high temperature conditions, resulting in reduced mechanical properties of PET plastic, which limits the application of chitosan in the flame retardant properties of PET plastic particles. Therefore, how to improve the flame retardant properties of PET plastic particles is a technical problem that needs to be solved at present. Summary of the invention

[0004] The object of the present invention is to provide a high temperature resistant flame retardant PET plastic particle and a preparation method thereof, so as to solve the problems in the background technology.

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

[0006] A high temperature resistant flame retardant PET plastic granule, comprising the following raw materials:

[0007] 90-100 parts by weight of PET resin, 8-13 parts by weight of modified flame retardant, 0.3-0.6 parts by weight of defoamer, 0.2-0.8 parts by weight of plasticizer, 1-2 parts by weight of antioxidant;

[0008] The modified flame retardant is prepared by the following steps:

[0009] A1. Add chitosan to an acetic acid solution, stir to dissolve, add a carbon nanotube dispersion, reflux at 90-95° C. for 5-6 h, then drop ammonia water, stir to mix, cool to 50-60° C., add glutaraldehyde, stir to react for 2-3 h, cool, centrifuge, wash with an acetic acid solution, and dry to obtain modified carbon nanotubes; use ammonia water as a catalyst and pentanediol as a cross-linking agent, and adopt a chemical deposition method to coat the double helical chitosan on the surface of the carbon nanotubes through the electrostatic adsorption between the amino groups on the chitosan and the carbonyl groups on the carbon nanotubes;

[0010] A2. Add polyphosphazene microspheres to N,N-dimethylformamide, stir to dissolve, add modified carbon nanotubes and pyridine, stir to react in an ice-water bath for 16-18 hours, and then filter, wash and dry to obtain a modified flame retardant; use ether as solvent and pyridine as acid binding agent to obtain a modified flame retardant with carbon nanotubes as core material and chitosan loaded with polyphosphazene microspheres as coating layer through substitution reaction between chloride ions on the polyphosphazene microspheres and hydroxyl groups on the surface of the modified carbon nanotubes.

[0011] Furthermore, the usage ratio of the acetic acid solution, chitosan, carbon nanotube dispersion, ammonia water and glutaraldehyde is 100mL: 0.5-1g: 15-20mL: 1.5mL: 0.5-1mL; the concentration of the acetic acid solution is 5wt%; and the concentration of the ammonia water is 6wt%.

[0012] Furthermore, the ratio of carbon nanotubes to deionized water in the carbon nanotube dispersion is 1-2 g:50 mL.

[0013] Furthermore, the dosage ratio of the N,N-dimethylformamide, polyphosphazene microspheres, modified carbon nanotubes and pyridine is 60 mL: 8-13 g: 2-4 g: 0.4-0.6 mL.

[0014] Furthermore, the polyphosphazene microspheres are prepared by the following steps:

[0015] Hexachlorocyclotriphosphazene is added to acetonitrile, ultrasonically dispersed, an acetonitrile solution of 4,4'-dihydroxydiphenyl sulfone is added, stirred and mixed, and triethylamine is added dropwise, and the dropping time is controlled to be 5-10 minutes. After the dropping is completed, the reaction is continued for 3-4 hours, and then filtered, washed with deionized water and anhydrous ethanol, and dried to obtain polyphosphazene microspheres; acetonitrile is used as a solvent, hexachlorocyclotriphosphazene and 4,4'-dihydroxydiphenyl sulfone are reaction monomers, and triethylamine is used as a catalyst to obtain polyphosphazene microspheres copolymerized by the two.

[0016] Furthermore, the usage ratio of acetonitrile, hexachlorocyclotriphosphazene, acetonitrile solution of 4,4'-dihydroxydiphenyl sulfone and triethylamine is 100mL: 0.5-2g: 30-40mL: 3-5mL;

[0017] Furthermore, the acetonitrile solution of 4,4'-dihydroxydiphenyl sulfone is prepared by dissolving 2-3 g of 4,4'-dihydroxydiphenyl sulfone in 70 mL of acetonitrile solution.

[0018] A method for preparing high temperature resistant flame retardant PET plastic particles comprises the following steps:

[0019] S1, adding PET resin, modified flame retardant, defoamer, plasticizer and antioxidant into a mixer and mixing them evenly to obtain a mixture;

[0020] S2, adding the mixed material into a screw extruder for melt extrusion, and obtaining high temperature resistant and flame retardant PET plastic particles after cooling, pelletizing and drying.

[0021] Beneficial effects of the present invention:

[0022] The surface of the modified flame retardant of the invention contains polyphosphazene microspheres, which form microscopic nano-scale protrusions, improve the roughness of the surface of the modified flame retardant, and enhance the interface bonding force between the modified flame retardant and the PET resin when mixed with the PET resin. When the PET plastic encounters a heat source and burns, the polyphosphazene microspheres on the molecules of the modified flame retardant can decompose phosphorus-containing active groups, effectively quench active free radicals generated when the PET plastic burns, terminate the chain combustion reaction, and cross-link to form carbon on the surface of the PET plastic, thereby inhibiting the volatilization of combustible gas. At the same time, the polyphosphazene microspheres generate non-toxic nitrogen-containing carbon after being heated. The burning gas can dilute the oxygen concentration around the combustion point of PET, thus improving the flame retardant properties of PET. The rough surface of the modified flame retardant can hinder the free movement of the PET molecular chain, thus showing a thickening and anti-melting droplet effect. In addition, the chitosan coating layer in the modified flame retardant will dehydrate the sugar ring during combustion, thus reducing the temperature around the combustion zone, and form a denser carbon layer with the carbon nanotube core material under the synergistic effect of phosphorus, thus reducing the permeability of the carbon layer, effectively improving the heat insulation effect, and quickly extinguishing the burning flame, further improving the flame retardant properties of TPE plastic particles.

[0023] The invention uses PET resin as a base material and improves the flame retardant performance of PET plastic particles by introducing a modified flame retardant. The modified flame retardant performs a substitution reaction between chlorine atoms on polyphosphazene microspheres and hydroxyl groups in chitosan segments coated on the surface of modified carbon nanometers. On the one hand, dehydration of chitosan on the modified flame retardant during processing can be effectively avoided to cause degradation of the PET resin, thereby improving the tensile strength of the PET plastic particles. On the other hand, the invention is conducive to removing chlorine atoms in the structure of the polyphosphazene microspheres, thereby avoiding generation of halogen-containing harmful gases during processing and flame retardant processes, thereby reducing the toxicity of the modified flame retardant. DETAILED DESCRIPTION

[0024] 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 described embodiments 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 creative work are within the scope of protection of the present invention.

[0025] Example 1

[0026] This embodiment provides a modified flame retardant, which is prepared by the following steps:

[0027] A1. Add 0.5 g of chitosan to 100 mL of 5 wt% acetic acid solution, stir to dissolve, add 15 mL of a dispersion prepared by 1 g of carbon nanotube dispersion in 50 mL of deionized water, reflux at 90 ° C for 5 h, then dropwise add 1.5 mL of 6 wt% ammonia water, stir to mix, cool to 50 ° C, add 0.5 mL of glutaraldehyde, stir to react for 2 h, cool, centrifuge, wash with 5 wt% acetic acid solution, and dry to obtain modified carbon nanotubes;

[0028] A2. Add 8 g of polyphosphazene microspheres to 60 mL of N,N-dimethylformamide, stir to dissolve, add 2 g of modified carbon nanotubes and 0.4 mL of pyridine, stir to react in an ice-water bath for 16 h, and then filter, wash and dry to obtain a modified flame retardant.

[0029] Example 2

[0030] This embodiment provides a modified flame retardant, which is prepared by the following steps:

[0031] A1. Add 0.7 g of chitosan to 100 mL of 5 wt% acetic acid solution, stir to dissolve, add 18 mL of a dispersion prepared by 1.5 g of carbon nanotube dispersion in 50 mL of deionized water, reflux at 93 ° C for 5.5 h, then dropwise add 1.5 mL of 6 wt% ammonia water, stir to mix, cool to 55 ° C, add 0.7 mL of glutaraldehyde, stir to react for 2.5 h, cool, centrifuge, wash with 5 wt% acetic acid solution, and dry to obtain modified carbon nanotubes;

[0032] A2. Add 10 g of polyphosphazene microspheres to 60 mL of N,N-dimethylformamide, stir to dissolve, add 2 g of modified carbon nanotubes and 0.5 mL of pyridine, stir to react in an ice-water bath for 17 h, and then filter, wash and dry to obtain a modified flame retardant.

[0033] Example 3

[0034] This embodiment provides a modified flame retardant, which is prepared by the following steps:

[0035] A1. Add 1 g of chitosan to 100 mL of 5 wt% acetic acid solution, stir to dissolve, add 20 mL of a dispersion prepared by 2 g of carbon nanotube dispersion in 50 mL of deionized water, reflux at 95 ° C for 6 h, then dropwise add 1.5 mL of 6 wt% ammonia water, stir to mix, cool to 60 ° C, add 1 mL of glutaraldehyde, stir to react for 3 h, cool, centrifuge, wash with 5 wt% acetic acid solution, and dry to obtain modified carbon nanotubes;

[0036] A2. Add 13 g of polyphosphazene microspheres to 60 mL of N,N-dimethylformamide, stir to dissolve, add 4 g of modified carbon nanotubes and 0.6 mL of pyridine, stir to react in an ice-water bath for 8 h, and then filter, wash and dry to obtain a modified flame retardant.

[0037] Example 4

[0038] This embodiment provides a polyphosphazene microsphere, which is prepared by the following steps:

[0039] B1. Add 2 g of 4,4'-dihydroxydiphenyl sulfone to 70 mL of acetonitrile and stir to dissolve to obtain an acetonitrile solution of 4,4'-dihydroxydiphenyl sulfone;

[0040] B2. Add 0.5 g of hexachlorocyclotriphosphazene to 100 mL of acetonitrile, disperse by ultrasonic, add 30 mL of 4,4'-dihydroxydiphenyl sulfone acetonitrile solution, stir to mix, and then drop 3 mL of triethylamine, control the dropping time to 5 min, and after the dropping is completed, continue the reaction for 3 h, and then filter, wash with deionized water and anhydrous ethanol, and dry to obtain polyphosphazene microspheres.

[0041] Example 5

[0042] This embodiment provides a polyphosphazene microsphere, which is prepared by the following steps:

[0043] B1. Add 2.5 g of 4,4'-dihydroxydiphenyl sulfone to 70 mL of acetonitrile and stir to dissolve to obtain an acetonitrile solution of 4,4'-dihydroxydiphenyl sulfone;

[0044] B2. Add 1 g of hexachlorocyclotriphosphazene to 100 mL of acetonitrile, disperse by ultrasonication, add 35 mL of 4,4'-dihydroxydiphenyl sulfone acetonitrile solution, stir to mix, and then drop 4 mL of triethylamine, control the dropping time to 7 min, and after the dropping is completed, continue the reaction for 3.5 h, and then filter, wash with deionized water and anhydrous ethanol, and dry to obtain polyphosphazene microspheres.

[0045] Example 6

[0046] This embodiment provides a polyphosphazene microsphere, which is prepared by the following steps:

[0047] B1. Add 3 g of 4,4'-dihydroxydiphenyl sulfone to 70 mL of acetonitrile and stir to dissolve to obtain an acetonitrile solution of 4,4'-dihydroxydiphenyl sulfone;

[0048] B2. Add 2 g of hexachlorocyclotriphosphazene to 100 mL of acetonitrile, disperse by ultrasonication, add 40 mL of 4,4'-dihydroxydiphenyl sulfone acetonitrile solution, stir and mix, then drop 5 mL of triethylamine, control the dropping time to 10 min, after the dropping is completed, continue the reaction for 4 h, then filter, wash with deionized water and anhydrous ethanol, and dry to obtain polyphosphazene microspheres.

[0049] Example 7

[0050] This embodiment provides a method for preparing high temperature resistant flame retardant PET plastic particles, comprising the following steps:

[0051] S1, adding 90 parts by weight of PET resin, 8 parts by weight of modified flame retardant, 0.3 parts by weight of defoamer, 0.2 parts by weight of plasticizer, and 1 part by weight of antioxidant into a mixer and mixing well to obtain a mixture;

[0052] S2, adding the mixed material into a screw extruder for melt extrusion, and obtaining high temperature resistant and flame retardant PET plastic particles after cooling, pelletizing and drying.

[0053] Example 8

[0054] This embodiment provides a method for preparing high temperature resistant flame retardant PET plastic particles, comprising the following steps:

[0055] S1, adding 95 parts by weight of PET resin, 10 parts by weight of modified flame retardant, 0.4 parts by weight of defoamer, 0.6 parts by weight of plasticizer, and 1.5 parts by weight of antioxidant into a mixer and mixing well to obtain a mixture;

[0056] S2, adding the mixed material into a screw extruder for melt extrusion, and obtaining high temperature resistant and flame retardant PET plastic particles after cooling, pelletizing and drying.

[0057] Example 9

[0058] This embodiment provides a method for preparing high temperature resistant flame retardant PET plastic particles, comprising the following steps:

[0059] S1, adding 100 parts by weight of PET resin, 13 parts by weight of modified flame retardant, 0.6 parts by weight of defoamer, 0.8 parts by weight of plasticizer, and 2 parts by weight of antioxidant into a mixer and mixing well to obtain a mixture;

[0060] S2, adding the mixed material into a screw extruder for melt extrusion, and obtaining high temperature resistant and flame retardant PET plastic particles after cooling, pelletizing and drying.

[0061] Comparative Example 1: Compared with Example 7, the modified flame retardant was replaced with chitosan in equal amount, and the rest was the same.

[0062] Comparative Example 2: Compared with Example 7, no modified flame retardant was added, and the rest was the same.

[0063] Comparative Example 3: Compared with Example 7, the modified flame retardant was replaced by polyphosphazene in equal amount, and the rest was the same.

[0064] Performance tests were performed on Examples 7 to 9 and Comparative Examples 1 to 3. Flame retardant performance test: the samples were made into 130 mm × 6.5 mm × 3 mm strips, referring to GB / T 2406-93, and the limiting oxygen index value of the strips was tested. The higher the limiting oxygen index value, the better the flame retardant performance; mechanical performance test: the tensile strength before and after combustion was tested, and the tensile strength was referred to GB / T1040-1992; vertical burning test: refer to GB / T2408-2008, and the results are shown in Table 1:

[0065] Table 1

[0066]

[0067]

[0068] It can be seen from Table 1 that the limiting oxygen index values ​​of the PET plastic particles prepared by the modified flame retardant in Examples 7-9 are significantly higher than those in Comparative Examples 1-3, and have good flame retardant properties, and the tensile strength before and after combustion is greater than that in Comparative Examples 1-3, and have good mechanical properties; in addition, compared with Comparative Examples 1 and 3, the combustion level of the PET plastic particles prepared in Example 7 can reach V-0 level, and there is no droplet phenomenon, indicating that the PET plastic particles prepared by the modified flame retardant have better flame retardant properties.

[0069] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0070] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A high temperature resistant flame retardant PET plastic particle, characterized in that: Including the following ingredients: 90-100 parts by weight of PET resin, 8-13 parts by weight of modified flame retardant, 0.3-0.6 parts by weight of defoamer, 0.2-0.8 parts by weight of plasticizer, 1-2 parts by weight of antioxidant; The modified flame retardant is prepared by the following steps: A1. Add chitosan to the acetic acid solution, stir to dissolve, add the carbon nanotube dispersion, reflux at 90-95°C for 5-6h, then drop ammonia water, stir to mix, cool to 50-60°C, add glutaraldehyde, stir to react for 2-3h, cool, centrifuge, wash with acetic acid solution, and dry to obtain modified carbon nanotubes; A2, add polyphosphazene microspheres to N,N-dimethylformamide, stir to dissolve, add modified carbon nanotubes and pyridine, stir to react in an ice water bath for 16-18 hours, and then filter, wash and dry to obtain a modified flame retardant; The polyphosphazene microspheres are prepared by the following steps: Add hexachlorocyclotriphosphazene to acetonitrile, disperse by ultrasonic, add 4,4'-dihydroxydiphenyl sulfone acetonitrile solution, stir and mix, then dropwise add triethylamine, control the dropwise addition time to be 5-10min, continue the reaction for 3-4h after the dropwise addition is completed, then filter, wash with deionized water and anhydrous ethanol, and dry to obtain polyphosphazene microspheres; The dosage ratio of acetonitrile, hexachlorocyclotriphosphazene, acetonitrile solution of 4,4'-dihydroxydiphenyl sulfone and triethylamine is 100mL: 0.5-2g: 30-40mL: 3-5mL; the concentration of the acetonitrile solution of 4,4'-dihydroxydiphenyl sulfone is 28.6-42.9mg / mL.

2. The high temperature resistant flame retardant PET plastic particles according to claim 1, characterized in that: The usage ratio of the acetic acid solution, chitosan, carbon nanotube dispersion, ammonia water and glutaraldehyde is 100 mL: 0.5-1 g: 15-20 mL: 1.5 mL: 0.5-1 mL; the concentration of the acetic acid solution is 5 wt %; and the concentration of the ammonia water is 6 wt %.

3. The high temperature resistant and flame retardant PET plastic particles according to claim 1, characterized in that: The usage ratio of carbon nanotubes to deionized water in the carbon nanotube dispersion is 1-2 g:50 mL.

4. The high temperature resistant and flame retardant PET plastic particles according to claim 1, characterized in that: The dosage ratio of the N,N-dimethylformamide, the polyphosphazene microspheres, the modified carbon nanotubes and the pyridine is 60 mL: 8-13 g: 2-4 g: 0.4-0.6 mL.

5. The method for preparing high temperature resistant flame retardant PET plastic particles according to claim 1, characterized in that: The following steps are involved: S1, adding PET resin, modified flame retardant, defoamer, plasticizer and antioxidant into a mixer and mixing them evenly to obtain a mixture; S2, adding the mixed material into a screw extruder for melt extrusion, and obtaining high temperature resistant and flame retardant PET plastic particles after cooling, pelletizing and drying.

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