Attapulgite-based flame retardant, preparation method thereof, and flame-retardant PET composite material and preparation method thereof

Abstract

The application provides a palygorskite-based flame retardant and a preparation method thereof, and a flame-retardant PET composite material and a preparation method thereof, and relates to the technical field of flame-retardant materials.The palygorskite-based flame retardant provided by the application is a core-shell structure microsphere, and the core-shell structure microsphere comprises palygorskite nanoparticles and chitosan coated on the surface of the palygorskite nanoparticles.The palygorskite-based flame retardant provided by the application is used for flame-retardant modification of PET material, and can effectively improve the mechanical properties of the PET material while significantly enhancing the flame-retardant properties of the PET material.

Description

Technical Field

[0001] This invention relates to the field of flame retardant materials technology, and in particular to an attapulgite-based flame retardant and its preparation method, and a flame retardant PET composite material and its preparation method. Background Technology

[0002] Polyethylene terephthalate (PET) is a semi-crystalline thermoplastic with excellent comprehensive properties, including heat resistance, electrical insulation, abrasion resistance, creep resistance, and chemical resistance. PET synthesis utilizes abundant and inexpensive raw materials, and its synthesis consumption is the lowest among the five major engineering plastics. Therefore, PET engineering plastics have a significant price advantage compared to other engineering plastics, possessing great market potential and the ability to partially replace engineering plastics such as PBT and PA. However, PET has unstable mechanical properties, poor high-temperature resistance, and is flammable with severe dripping during combustion, which greatly limits its application in engineering fields. Therefore, flame-retardant modification of PET is essential. Current technology commonly uses flame retardants to modify PET materials, such as bromotriazine, decabromodiphenyl ether, or phosphorus-based organic flame retardants. These types of flame retardants produce corrosive gases and dense smoke during action and decompose to produce extractable organic compounds that are difficult to degrade and cause persistent environmental damage. Metal hydroxide inorganic flame retardants, such as aluminum hydroxide and magnesium hydroxide, decompose upon heating to release water vapor without producing toxic gases. However, metal hydroxides are generally added in high amounts, which often leads to a significant reduction in the mechanical properties of the matrix material. Summary of the Invention

[0003] In view of this, the present invention aims to provide an attapulgite-based flame retardant and its preparation method, as well as a flame-retardant PET composite material and its preparation method. The attapulgite-based flame retardant provided by the present invention can significantly enhance the flame-retardant properties of PET materials while effectively improving their mechanical properties.

[0004] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0005] This invention provides an attapulgite-based flame retardant, wherein the attapulgite-based flame retardant is a core-shell structured microsphere, and the core-shell structured microsphere comprises attapulgite nanoparticles and chitosan coated on the surface of the attapulgite nanoparticles.

[0006] Preferably, the mass ratio of the attapulgite nanoparticles to chitosan is (20-30):(5-10).

[0007] This invention provides a method for preparing the attapulgite-based flame retardant described above, comprising the following steps:

[0008] An acetic acid solution of chitosan was mixed with attapulgite nanoparticles to obtain an aqueous phase.

[0009] Toluene is mixed with an emulsifier to obtain an oil phase;

[0010] The aqueous phase is added to the oil phase for emulsification to obtain an emulsion;

[0011] The emulsion is mixed with formaldehyde, and the pH of the resulting mixture is adjusted to 9-10 to carry out an aldehyde-amine condensation reaction. The resulting reaction solution is then subjected to solid-liquid separation to obtain the attapulgite-based flame retardant.

[0012] Preferably, the degree of deacetylation of the chitosan is 50-70%; the mass ratio of the attapulgite nanoparticles to the chitosan is (20-30):(5-10); and the mass content of chitosan in the acetic acid solution is 3-5%.

[0013] Preferably, the emulsifier includes Span-80 and / or Tween; the mass fraction of the emulsifier in the oil phase is 3-5%.

[0014] Preferably, the mass ratio of the aqueous phase to the oil phase is 1:7 to 10.

[0015] Preferably, the formaldehyde content is 5-8% of the chitosan content; the aldehyde-amine condensation reaction is carried out at a temperature of 40-70°C for 1-3 hours.

[0016] This invention provides a flame-retardant PET composite material, comprising the following raw materials in parts by weight:

[0017]

[0018] The flame retardant is the attapulgite-based flame retardant described in the above technical solution or the attapulgite-based flame retardant prepared by the preparation method described in the above technical solution.

[0019] This invention provides a method for preparing the flame-retardant PET composite material described above, comprising the following steps:

[0020] The flame-retardant PET composite material is obtained by mixing PET resin, flame retardant, lubricant, antioxidant, coupling agent and nucleating agent and then performing twin-screw melt extrusion.

[0021] Preferably, the twin-screw melt extrusion has 10 temperature control zones. Starting from the melting section, the temperatures of the 10 temperature control zones are sequentially 220–230°C, 220–230°C, 220–240°C, 220–240°C, 240–250°C, 240–250°C, 240–250°C, 240–250°C, 220–250°C, and 220–250°C. The screw speed of the twin-screw melt extrusion is 150–300 rpm.

[0022] This invention provides an attapulgite-based flame retardant, wherein the attapulgite-based flame retardant is a core-shell structured microsphere, and the core-shell structured microsphere comprises attapulgite nanoparticles and chitosan coated on the surface of the attapulgite nanoparticles. This invention utilizes the negatively charged nature of attapulgite and the positively charged chitosan to form a stable core-shell structure with attapulgite as the hard core and chitosan as the soft shell through electrostatic attraction. The chitosan surface has numerous hydroxyl groups that react with the PET resin matrix to form a stable bond, resulting in good compatibility between the core-shell structure and the PET resin matrix, effectively transferring forces and significantly improving the impact strength of the PET resin. In the core-shell structure, the attapulgite contains a large amount of water of crystallization. During thermal decomposition, this water of crystallization forms water vapor, isolating oxygen and carrying away a significant amount of heat. Simultaneously, it forms a dense oxide isolation layer mainly composed of MgO and Al2O3 with a stable structure, achieving a flame-retardant effect. Furthermore, the formed water vapor acts as a foaming agent during the chitosan carbonization process, helping to form a porous carbon layer that effectively isolates heat and oxygen transfer, improving flame-retardant efficiency. Therefore, using the attapulgite-based flame retardant provided by this invention for the flame-retardant modification of PET materials can significantly enhance the flame-retardant properties of PET materials while effectively improving their mechanical properties.

[0023] This invention provides a method for preparing the attapulgite-based flame retardant described in the above technical solution. This invention utilizes electrostatics to uniformly disperse attapulgite nanoparticles in an acetic acid solution of chitosan, thus solving the problem of easy agglomeration of nanoparticles. Then, a core-shell structured microsphere with attapulgite as the hard core and chitosan as the soft shell is prepared by emulsification. Detailed Implementation

[0024] This invention provides an attapulgite-based flame retardant, wherein the attapulgite-based flame retardant is a core-shell structured microsphere, the core-shell structured microsphere comprising attapulgite nanoparticles and chitosan coating the surface of the attapulgite nanoparticles. In this invention, the preferred mass ratio of the attapulgite nanoparticles to chitosan is (20-30):(5-10), more preferably (20-30):10.

[0025] Attapulgite is a layered, chain-like magnesium- and aluminosilicate clay mineral with a rod-shaped crystal structure, ranging from 500 to 5000 nm in length and 20 to 40 nm in diameter. It is a natural one-dimensional nanomaterial. Attapulgite's unique one-dimensional structure can impart excellent reinforcing and strengthening properties to polymer materials. In addition, attapulgite contains a large amount of water of crystallization, hydroxyl structural water, and zeolite molecular water, which can generate water vapor at high temperatures and absorb heat, thus giving it certain flame-retardant properties. Furthermore, attapulgite can form an oxide isolation layer mainly composed of MgO and Al2O3 in high-temperature environments, exhibiting good thermal stability and flame-retardant effects. Chitosan is a natural, readily available, and inexpensive polysaccharide polymer that is biodegradable, biocompatible, environmentally friendly, and non-toxic. The chitosan molecular skeleton is rich in carbon and contains a certain number of side-chain hydroxyl and amino groups. During thermal decomposition, these groups can carbonize within the polymer, hindering combustion and releasing non-toxic, non-corrosive, and non-flammable gases such as CO2, NH3, and N2, thus providing flame retardancy. Furthermore, the amino and hydroxyl groups on the chitosan molecule give it good reactivity.

[0026] This invention utilizes the negatively charged properties of attapulgite clay and the positively charged chitosan to form a stable core-shell structure with attapulgite as the hard core and chitosan as the soft shell through electrostatic attraction. The chitosan surface has a large number of hydroxyl groups that can react with the PET resin matrix to form a stable bond, giving the core-shell structure good compatibility with the PET resin matrix and effectively transferring forces, greatly improving the impact strength of the PET resin. In the core-shell structure, attapulgite clay contains a large amount of water of crystallization. During the thermal decomposition process, the water of crystallization forms water vapor, which isolates oxygen and carries away a large amount of heat. At the same time, it forms a stable oxide isolation layer mainly composed of MgO and Al2O3, achieving a flame-retardant effect. In addition, the water vapor formed acts as a foaming agent during the carbonization process of chitosan, which helps to form a porous carbon layer, effectively isolating heat and oxygen transfer and improving the flame-retardant efficiency.

[0027] This invention provides a method for preparing the attapulgite-based flame retardant described above, comprising the following steps:

[0028] An acetic acid solution of chitosan was mixed with attapulgite nanoparticles to obtain an aqueous phase.

[0029] Toluene is mixed with an emulsifier to obtain an oil phase;

[0030] The aqueous phase is added to the oil phase for emulsification to obtain an emulsion;

[0031] The emulsion is mixed with formaldehyde, and the pH of the resulting mixture is adjusted to 9-10 to carry out an aldehyde-amine condensation reaction. The resulting reaction solution is then subjected to solid-liquid separation to obtain the attapulgite-based flame retardant.

[0032] Unless otherwise specified, all raw materials involved in this invention are commercially available products well known to those skilled in the art.

[0033] This invention involves mixing an acetic acid solution of chitosan with attapulgite nanoparticles to obtain an aqueous phase. In this invention, the degree of deacetylation of the chitosan is preferably 50-70%; the mass content of chitosan in the acetic acid solution is preferably 3-5%, more preferably 4%; the acetic acid solution is specifically obtained by dissolving chitosan in an acetic acid solution, which serves two purposes: dissolving the chitosan and adjusting the pH of the solution to acidity, under which the chitosan surface protonates and becomes positively charged. In this invention, the mass ratio of attapulgite powder to chitosan is preferably (20-30):(5-10), more preferably (20-30):10. In this invention, attapulgite nanoparticles are preferably added to the acetic acid solution of chitosan for mixing. The mixing is preferably ultrasonically dispersed, and the ultrasonic dispersion time is preferably 30 minutes. During the ultrasonic dispersion process, the attapulgite nanoparticles are uniformly dispersed in the acetic acid solution of chitosan by electrostatic action. The negatively charged surface of the attapulgite and the positively charged chitosan form an electrostatic attraction, so that the nano-attapulgite is uniformly adsorbed on the surface of chitosan.

[0034] This invention involves mixing toluene with an emulsifier to obtain an oil phase. In this invention, the emulsifier preferably includes Span-80 and / or Tween, more preferably Span-80; the mass fraction of the emulsifier in the oil phase is preferably 3-5%, more preferably 4%. This invention does not have particular requirements for the method of mixing the toluene and the emulsifier, as long as the mixing is uniform.

[0035] After obtaining the aqueous phase and the oil phase, the present invention adds the aqueous phase to the oil phase for emulsification to obtain an emulsion. In the present invention, the mass ratio of the aqueous phase to the oil phase is preferably 1:7 to 10, more preferably 1:7 to 8. In the present invention, the emulsification method is preferably stirring emulsification, the stirring speed of which is preferably 1000 to 1500 rpm, and the time is preferably 10 to 30 min. After emulsification, core-shell structured microspheres with attapulgite as the hard core and chitosan as the soft shell are formed.

[0036] After obtaining the emulsion, the present invention mixes the emulsion with formaldehyde, adjusts the pH of the resulting mixture to 9-10, and performs an aldehyde-amine condensation reaction. The resulting reaction solution is then subjected to solid-liquid separation to obtain the attapulgite-based flame retardant. In the present invention, the mass of the formaldehyde is preferably 5-8% of the mass of chitosan. In the present invention, the reagent used to adjust the pH is preferably a 1 mol / L sodium hydroxide solution. In the present invention, the temperature of the aldehyde-amine condensation reaction is preferably 40-70℃, more preferably 70℃, and the time is preferably 1-3 hours, more preferably 2 hours. During the aldehyde-amine condensation reaction, the aldehyde groups in the formaldehyde react with the amino groups in the chitosan to form a Schiff base structure. This reaction can relatively stably fix the helical configuration of the chitosan molecules, ordering the disordered chitosan molecular chains to form chitosan microspheres. In this invention, the solid-liquid separation method is preferably centrifugal filtration; after solid-liquid separation, the obtained precipitate is preferably washed and vacuum dried to obtain the attapulgite-based flame retardant; the washing preferably includes washing with deionized water and washing with anhydrous ethanol, and this invention preferably repeatedly washes with deionized water and anhydrous ethanol until the precipitate is washed to neutral; this invention does not have special requirements for the temperature and time of the vacuum drying, drying to constant weight is sufficient.

[0037] This invention provides a flame-retardant PET composite material, comprising the following raw materials in parts by weight:

[0038]

[0039] The flame retardant is the attapulgite-based flame retardant described in the above technical solution or the attapulgite-based flame retardant prepared by the preparation method described in the above technical solution.

[0040] The flame-retardant PET composite material provided by this invention comprises 60-80 parts by weight of PET resin, specifically 60, 70, or 80 parts. This invention does not have specific requirements regarding the source of the PET resin; any PET resin from a source well-known to those skilled in the art is acceptable. The PET resin can be virgin PET resin, recycled PET resin, or a mixture of virgin and recycled PET resin. In this invention, the intrinsic viscosity of the PET resin is preferably 0.45-1.1 dL / g, more preferably 0.6-0.8 dL / g.

[0041] Based on the mass fraction of the PET resin, the flame-retardant PET composite material provided by this invention comprises 20-40 parts of a flame retardant in its preparation raw materials. The flame retardant is the attapulgite-based flame retardant described in the above technical solutions or the attapulgite-based flame retardant prepared by the preparation method described in the above technical solutions. Using the attapulgite-based flame retardant for flame-retardant modification of PET materials can significantly enhance the flame-retardant properties of PET materials while effectively improving their mechanical properties.

[0042] Based on the mass fraction of the PET resin, the flame-retardant PET composite material provided by the present invention comprises 0.1 to 0.5 parts of lubricant, preferably 0.3 to 0.5 parts. In the present invention, the lubricant preferably comprises one or more of saturated hydrocarbon lubricants, metal soap lubricants, aliphatic phenolic lubricants, fatty acid lubricants, fatty alcohol lubricants, and silicone powder; more preferably, a mixture of silicone powder and fatty acid lubricants; and even more preferably, a mixture of silicone powder and pentaerythritol stearate, wherein the mass ratio of silicone powder to pentaerythritol stearate is preferably 2:3. In the present invention, the lubricant can increase the flowability of the PET composite material system.

[0043] Based on the mass fraction of the PET resin, the flame-retardant PET composite material provided by the present invention comprises 0.3 to 0.6 parts, preferably 0.4 to 0.5 parts, of antioxidants in its preparation raw materials. In the present invention, the antioxidants preferably include one or more of antioxidants 1010, 168, 126, 225, and 215, more preferably antioxidants 1010 and 168, and the mass ratio of antioxidant 1010 to antioxidant 168 is preferably 1:1. In the present invention, the antioxidants can reduce the degradation of molecular chains during the processing of PET resin.

[0044] Based on the mass fraction of the PET resin, the flame-retardant PET composite material provided by the present invention comprises 0.1 to 0.5 parts, preferably 0.3 to 0.5 parts, of a coupling agent. In the present invention, the coupling agent is preferably a silane coupling agent, the general formula of which is RSiX3, where R represents amino, mercapto, vinyl, epoxy, cyano, or methacryloxy, and X represents a hydrolyzable alkoxy group. In the embodiments of the present invention, the silane coupling agent is preferably γ-aminopropyltriethoxysilane (KH550). In the present invention, the coupling agent can increase the compatibility between systems.

[0045] Based on the mass fraction of the PET resin, the nucleating agent used in the preparation of the flame-retardant PET composite material provided by the present invention comprises 0.1 to 0.5 parts, preferably 0.3 to 0.5 parts. In the present invention, the nucleating agent is preferably sodium benzoate. In the present invention, the nucleating agent can accelerate the crystallization rate of PET, making the PET crystals more dense and helping to enhance its mechanical properties.

[0046] The flame-retardant PET composite material provided by this invention not only has excellent flame-retardant properties, but also good mechanical properties.

[0047] This invention provides a method for preparing the flame-retardant PET composite material described above, comprising the following steps:

[0048] The flame-retardant PET composite material is obtained by mixing PET resin, flame retardant, lubricant, antioxidant, coupling agent and nucleating agent and then performing twin-screw melt extrusion.

[0049] In this invention, the mixing of the PET resin, flame retardant, lubricant, antioxidant, coupling agent, and nucleating agent is preferably carried out in a high-speed mixer, and the mixing time is preferably 5 minutes. In this invention, the twin-screw melt extrusion is specifically carried out in a twin-screw extruder. This invention does not have special requirements for the twin-screw extruder; a twin-screw extruder well-known to those skilled in the art can be used. In this invention, the twin-screw melt extrusion preferably has 10 temperature control zones. Starting from the melting section, the temperatures of the 10 temperature control zones are preferably sequentially 220–230°C, 220–230°C, 220–240°C, 220–240°C, 240–250°C, 240–250°C, 240–250°C, 240–250°C, 220–250°C, and 220–250°C. The screw speed of the twin-screw melt extrusion is preferably 150–300 rpm, more preferably 200 rpm.

[0050] The following detailed description, in conjunction with embodiments, illustrates the attapulgite-based flame retardant and its preparation method, as well as the flame-retardant PET composite material and its preparation method provided by the present invention. However, these descriptions should not be construed as limiting the scope of protection of the present invention.

[0051] The raw materials used in each implementation case are as follows:

[0052] The PET resin used is recycled PET resin with an intrinsic viscosity of 0.75 dL / g, and is rPET-PCR78AP produced by Ningbo Jianfeng New Materials Co., Ltd.

[0053] The chitosan used is food-grade water-soluble chitosan produced by Shaanxi Chenming Biotechnology Co., Ltd., with a degree of deacetylation of 70%.

[0054] Antioxidants 1010 and 168, produced by BASF AG of Germany, are selected. The main antioxidant 1010 and the auxiliary antioxidant 168 work synergistically with a mass ratio of 1:1.

[0055] The lubricants selected are silicone powder F308 and pentaerythritol stearate F301 produced by Guangzhou Jufeng Chemical Technology Co., Ltd.

[0056] The coupling agent used is KH550, produced by Qingdao Hengda Zhongcheng Technology Co., Ltd., whose full name is γ-aminopropyltriethoxysilane.

[0057] Example 1

[0058] An attapulgite-based flame retardant, prepared by the following method:

[0059] (1) Weigh each component according to weight: 15 parts by weight of attapulgite nanopowder and 5 parts by weight of chitosan.

[0060] (2) Chitosan was dissolved in acetic acid solution, with a chitosan mass fraction of 4%. The resulting chitosan acetic acid solution was placed in a round-bottom flask, and the attapulgite powder from (1) was added. The mixture was ultrasonically dispersed for 30 min. The resulting mixed solution was added to 1000 parts by mass of toluene solution (containing 38.5 parts by mass of Span-80), and stirred thoroughly to obtain an emulsion. 0.25 parts by mass of formaldehyde was added to the emulsion, and the pH of the resulting condensation reaction solution was adjusted to 10 with 1 mol / L sodium hydroxide solution. The temperature was raised to 70°C, and the reaction was carried out for 2 h. After centrifugation and filtration, the precipitate was obtained. The precipitate was washed repeatedly with deionized water and anhydrous ethanol, and then dried under vacuum to obtain attapulgite / chitosan composite microspheres with a core-shell structure, i.e., attapulgite-based flame retardant.

[0061] A flame-retardant PET composite material, prepared by the following method:

[0062] Weigh the following components by weight: 80 parts by weight of PET resin, 20 parts by weight of the above-mentioned attapulgite-based flame retardant, 0.5 parts by weight of antioxidant, 0.5 parts by weight of lubricant, 0.5 parts by weight of coupling agent, and 0.5 parts by weight of nucleating agent. Mix them in a high-speed mixer for 5 minutes, and then feed them into a twin-screw extruder. The screw speed is controlled at 200 rpm. After melt extrusion and granulation, an attapulgite-reinforced flame-retardant PET composite material is obtained. The twin-screw extruder is equipped with 10 temperature control zones. The temperature of temperature control zones 1-2 is 220-230℃, the temperature of temperature control zones 3-4 is 220-240℃, the temperature of temperature control zones 5-6 is 240-250℃, the temperature of temperature control zones 7-8 is 240-250℃, and the temperature of temperature control zones 9-10 is 220-250℃. The twin-screw extruder has two vacuum ports, the first at the beginning of the melting section and the second at the metering section.

[0063] Example 2

[0064] An attapulgite-based flame retardant, prepared by the following method:

[0065] (1) Weigh each component according to weight: 20 parts by weight of attapulgite nanopowder and 10 parts by weight of chitosan.

[0066] (2) Chitosan was dissolved in acetic acid solution, with a chitosan mass fraction of 4%. The resulting chitosan acetic acid solution was placed in a round-bottom flask, and the attapulgite powder from (1) was added. The mixture was ultrasonically dispersed for 30 min. The mixed solution was added to 2000 parts by mass of toluene solution (containing 77 parts by mass of Span-80), and stirred thoroughly to obtain an emulsion. 0.5 parts by mass of formaldehyde was added to the emulsion, and the pH of the resulting condensation reaction solution was adjusted to 10 with 1 mol / L sodium hydroxide solution. The temperature was raised to 70°C, and the reaction was carried out for 2 h. After centrifugation and filtration, the precipitate was obtained. The precipitate was washed repeatedly with deionized water and anhydrous ethanol, and then dried under vacuum to obtain attapulgite / chitosan composite microspheres with a core-shell structure, i.e., attapulgite-based flame retardant.

[0067] A flame-retardant PET composite material, prepared by the following method:

[0068] Weigh the following components by weight: 70 parts by weight of PET resin, 30 parts by weight of the above-mentioned attapulgite-based flame retardant, 0.5 parts by weight of antioxidant, 0.5 parts by weight of lubricant, 0.5 parts by weight of coupling agent, and 0.5 parts by weight of nucleating agent. Mix them in a high-speed mixer for 5 minutes, then feed them into a twin-screw extruder with the screw speed controlled at 200 rpm. After melt extrusion and granulation, an attapulgite-reinforced flame-retardant PET composite material is obtained. The twin-screw extruder is equipped with 10 temperature control zones: temperature control zones 1-2 are 220-230℃, temperature control zones 3-4 are 220-240℃, temperature control zones 5-6 are 240-250℃, temperature control zones 7-8 are 240-250℃, and temperature control zones 9-10 are 220-250℃. The twin-screw extruder has two vacuum ports: the first is at the beginning of the melting section, and the second is at the metering section.

[0069] Example 3

[0070] An attapulgite-based flame retardant, prepared by the following method:

[0071] (1) Weigh each component according to weight: 30 parts by weight of attapulgite nanopowder and 10 parts by weight of chitosan.

[0072] (2) Chitosan was dissolved in acetic acid solution, with a chitosan mass fraction of 4%. The resulting chitosan acetic acid solution was placed in a round-bottom flask, and the attapulgite powder from (2) was added. The mixture was ultrasonically dispersed for 30 min. The resulting mixed solution was added to 2000 parts by mass of toluene solution (containing 77 parts by mass of Span-80), and stirred thoroughly to obtain an emulsion. 0.5 parts by mass of formaldehyde was added to the emulsion, and the pH of the resulting condensation reaction solution was adjusted to 10 with 1 mol / L sodium hydroxide solution. The temperature was raised to 70°C, and the reaction was carried out for 2 h. After centrifugation and filtration, the precipitate was obtained. The precipitate was repeatedly washed with deionized water and anhydrous ethanol, and then vacuum dried to obtain attapulgite / chitosan composite microspheres with a core-shell structure, i.e., attapulgite-based flame retardant.

[0073] A flame-retardant PET composite material, prepared by the following method:

[0074] Weigh the following components by weight: 60 parts by weight of PET resin, 40 parts by weight of the above-mentioned attapulgite-based flame retardant, 0.5 parts by weight of antioxidant, 0.5 parts by weight of lubricant, 0.5 parts by weight of coupling agent, and 0.5 parts by weight of nucleating agent. Mix them in a high-speed mixer for 5 minutes, then feed them into a twin-screw extruder with the screw speed controlled at 200 rpm. After melt extrusion and granulation, the attapulgite-reinforced flame-retardant PET composite material is obtained. The twin-screw extruder is equipped with 10 temperature control zones: temperature control zones 1-2 are 220-230℃, temperature control zones 3-4 are 220-240℃, temperature control zones 5-6 are 240-250℃, temperature control zones 7-8 are 240-250℃, and temperature control zones 9-10 are 220-250℃. The twin-screw extruder has two vacuum ports: the first is at the beginning of the melting section, and the second is at the metering section.

[0075] Comparative Example 1

[0076] A flame-retardant PET composite material, prepared by the following method:

[0077] (1) Weigh each component according to weight: 20 parts by weight of attapulgite nanopowder and 10 parts by weight of chitosan.

[0078] (2) Weigh the following components by weight: 70 parts by weight of PET resin, 20 parts by weight of (1) attapulgite powder, 10 parts by weight of chitosan, 0.5 parts by weight of antioxidant, 0.5 parts by weight of lubricant, 0.5 parts by weight of coupling agent, and 0.5 parts by weight of nucleating agent. Mix them in a high-speed mixer for 5 minutes, and then feed them into a twin-screw extruder. Control the screw speed at 200 rpm. After melt extrusion and granulation, obtain attapulgite-reinforced flame-retardant PET composite. Materials; the twin-screw extruder is equipped with 10 temperature control zones, with temperature control zones 1-2 at 220-230℃, temperature control zones 3-4 at 220-240℃, temperature control zones 5-6 at 240-250℃, temperature control zones 7-8 at 240-250℃, and temperature control zones 9-10 at 220-250℃; the twin-screw extruder has two vacuum ports, the first at the beginning of the melting section and the second at the metering section.

[0079] The performance of the flame-retardant PET composite materials prepared in Examples 1-3 and Comparative Example 1 was tested, and the test results are shown in Table 1:

[0080] Table 1. Performance test results of flame-retardant PET composite materials prepared in Examples 1-3 and Comparative Example 1.

[0081]

[0082] As can be seen from the above embodiments, the attapulgite-based flame retardant provided by the present invention is used for flame retardant modification of PET materials. The resulting flame retardant PET composite material not only has excellent flame retardant properties, but also good mechanical properties.

[0083] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A flame-retardant PET composite material, characterized in that, It is prepared from the following raw materials in parts by weight: 60-80 parts of PET resin 20-40 parts flame retardant Lubricant 0.1~0.5 parts, Antioxidant 0.3~0.6 parts, 0.1-0.5 parts of coupling agent, Nucleating agent 0.1~0.5 parts; The flame retardant is an attapulgite-based flame retardant, which is a core-shell structured microsphere. The core-shell structured microsphere is composed of attapulgite nanoparticles and chitosan coated on the surface of the attapulgite nanoparticles. The mass ratio of the attapulgite nanoparticles to chitosan is (20~30):(5~10). The preparation method of the attapulgite-based flame retardant includes the following steps: An acetic acid solution of chitosan was mixed with attapulgite nanoparticles to obtain an aqueous phase. Toluene is mixed with an emulsifier to obtain an oil phase; The aqueous phase is added to the oil phase for emulsification to obtain an emulsion; The emulsion is mixed with formaldehyde, and the pH of the resulting mixture is adjusted to 9-10 to carry out an aldehyde-amine condensation reaction. The resulting reaction solution is then subjected to solid-liquid separation to obtain the attapulgite-based flame retardant. The preparation method of the flame-retardant PET composite material includes the following steps: The flame-retardant PET composite material is obtained by mixing PET resin, flame retardant, lubricant, antioxidant, coupling agent and nucleating agent and then performing twin-screw melt extrusion.

2. The flame-retardant PET composite material according to claim 1, characterized in that, The degree of deacetylation of the chitosan is 50-70%; the mass ratio of the attapulgite nanoparticles to the chitosan is (20-30):(5-10); and the mass content of chitosan in the acetic acid solution is 3-5%.

3. The flame-retardant PET composite material according to claim 1, characterized in that, The emulsifier includes Span-80 and / or Tween; the mass fraction of the emulsifier in the oil phase is 3-5%.

4. The flame-retardant PET composite material according to claim 1, characterized in that, The mass ratio of the aqueous phase to the oil phase is 1:7~10.

5. The flame-retardant PET composite material according to claim 1, characterized in that, The formaldehyde content is 5-8% of the chitosan content; the aldehyde-amine condensation reaction is carried out at a temperature of 40-70°C for 1-3 hours.

6. A method for preparing the flame-retardant PET composite material according to any one of claims 1 to 5, characterized in that, Includes the following steps: The flame-retardant PET composite material is obtained by mixing PET resin, flame retardant, lubricant, antioxidant, coupling agent and nucleating agent and then performing twin-screw melt extrusion.

7. The preparation method according to claim 6, characterized in that, The twin-screw melt extruder has 10 temperature control zones. Starting from the melting section, the temperatures of the 10 temperature control zones are sequentially 220~230℃, 220~230℃, 220~240℃, 220~240℃, 240~250℃, 240~250℃, 240~250℃, 220~250℃, and 220~250℃. The screw speed of the twin-screw melt extruder is 150~300 rpm.

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