A PET environmentally friendly material and its preparation method

Abstract

This invention relates to an environmentally friendly PET material and its preparation method, belonging to the field of recycled environmentally friendly materials technology. The PET environmentally friendly material comprises: 12-16 wt% reinforcing filler, 4.2-5.8 wt% toughening agent, 8.2-10.5 wt% flame retardant regenerator, 2.4-3 wt% lubricant, and 0.13-0.17 wt% antioxidant, with the balance being recycled PET. The flame retardant regenerator is modified by replacing butyl glycolate and 7-octenyltrichlorosilane to form a modified carrier with a branched ester structure and alkenyl groups, followed by double bond addition with DOPO to introduce a functional flame-retardant structure. The introduction of the flame retardant regenerator achieves a balance between high-efficiency flame retardancy and toughening of recycled PET. Its environmental friendliness, performance advantages, and low processing cost align with the trends of circular economy and green manufacturing.

Description

Technical Field

[0001] This invention belongs to the field of recycled and environmentally friendly materials technology, specifically relating to a PET environmentally friendly material and its preparation method. Background Technology

[0002] Polyethylene terephthalate (PET) is a high-performance engineering plastic with excellent mechanical strength, heat resistance, and chemical stability, and is widely used in packaging, fibers, electronic devices, and automotive parts. While inherently a recyclable and environmentally friendly material, its actual recycling rate is low, primarily due to the high costs of existing chemical and biological recycling methods. Currently, PET is mainly recycled through physical methods.

[0003] Physical recycling refers to the process of converting waste PET into recycled granules through crushing, washing, and melt granulation. These granules are then modified through blending to acquire different properties to meet application requirements. Flame retardant modification, for example, is applied to engineering materials such as electronic and automotive parts, effectively consuming waste PET, achieving efficient PET recycling, and reducing environmental pollution. However, current flame retardant modification technology for recycled PET faces a core challenge: DOPO (9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide) is a commonly used and highly effective flame retardant in PET. However, DOPO has low polarity and insufficient interfacial compatibility with PET. Furthermore, the large amount of impurities remaining in recycled PET increases the difficulty of dispersing DOPO. In actual use, the proportion of flame retardant used does not match the actual flame retardant effect. Moreover, the molecular chains in recycled PET are broken, crystallinity decreases, and mechanical properties have already deteriorated. The introduction of DOPO further exacerbates the deterioration of the material's mechanical properties, making it difficult for traditional blending processes to balance flame retardancy and mechanical properties. Summary of the Invention

[0004] In order to solve the technical problems mentioned in the background art, the purpose of this invention is to provide a PET environmentally friendly material and its preparation method.

[0005] The objective of this invention can be achieved through the following technical solutions:

[0006] A type of environmentally friendly PET material, specifically composed of: 12-16wt% reinforcing filler, 4.2-5.8wt% toughening agent, 8.2-10.5wt% flame retardant recycler, 2.4-3wt% lubricant, and 0.13-0.17wt% antioxidant, with the balance being recycled PET.

[0007] The flame retardant recycling agent is made by the following method:

[0008] Step A1: Mix butyl glycolate and anhydrous tetrahydrofuran, purge the air in the reaction system with dry nitrogen, control the temperature in an ice-water bath at 0-5℃, slowly add 7-octenyltrichlorosilane while stirring, and react for 1.5-2h. After returning to room temperature, add triethylamine and continue the reaction for 0.5-0.8h. After filtration, remove tetrahydrofuran by rotary evaporation to obtain the modified support.

[0009] Furthermore, the ratio of 7-octenyltrichlorosilane, butyl glycolate, triethylamine, and anhydrous tetrahydrofuran is 10 mmol: 30 mmol: 4.2-5.5 mL: 30-35 mL. The active chlorosilane substitution reaction of butyl glycolate with 7-octenyltrichlorosilane follows the specific reaction route as follows:

[0010]

[0011] Step A2: Mix DOPO and dioxane, then add the modified carrier and mix. Heat to 45-60℃, slowly add boron trifluoride ether and stir for 2.8-3.5h. Then heat to reflux for 1-1.3h, add water to wash, and vacuum dry the precipitate to obtain the flame retardant regenerator.

[0012] Furthermore, the ratio of modified support, DOPO, boron trifluoride diethyl ether, and dioxane was 10 mmol: 10 mmol: 0.1-0.12 mL: 40-50 mL. DOPO underwent an addition reaction with the unsaturated double bonds in the modified support, and the specific reaction route is as follows:

[0013]

[0014] Preferably, the reinforcing filler is silane-modified silica.

[0015] Preferably, the toughening agent is POE-g-MAH.

[0016] Preferably, the lubricant is a compound of silicone powder and ethylene bis-stearamide.

[0017] A method for preparing PET environmentally friendly material specifically involves: mixing toughening agent, flame retardant recycler, lubricant, antioxidant and recycled PET, feeding the mixture from the main feed port of an extruder, feeding reinforcing filler from the side feed port, and extruding and pelletizing the mixture after plasticizing and mixing to obtain PET environmentally friendly material.

[0018] Preferably, the temperatures of each extrusion section during the plasticizing and mixing process are set as follows: feeding section: 250-260℃, compression section: 260-270℃, homogenization section: 270-285℃, and die section: 260-270℃.

[0019] The beneficial effects of this invention are:

[0020] This invention is based on environmentally friendly recycled PET material. By introducing a specially developed flame-retardant recycling agent for blending modification, high-performance reuse of recycled PET is achieved. This flame-retardant recycling agent is modified by replacing butyl glycolate and 7-octenyltrichlorosilane to form a modified carrier with a branched ester structure and alkenyl groups. Subsequently, DOPO is added to its double bonds to introduce a functional flame-retardant structure. Compared with existing recycled flame-retardant PET materials, the flame-retardant recycling agent of this invention contains a branched butyl ester structure modification, which matches the polarity of PET, exhibiting good compatibility. It can be effectively dispersed during the melting and mixing process and effectively dispersed during molding and cooling. During the process, the branched butyl ester structure can entangle with the PET molecular chains, reducing the thermal migration of the DOPO functional structure. This allows for stable dispersion in recycled PET, rapidly forming a continuous and dense protective layer during material combustion. This effectively isolates heat and oxygen, significantly improving the limiting oxygen index of the material. The continuous and uniform protective layer inhibits the generation of molten droplets, thus achieving excellent flame retardant effects. In addition, the uniformly dispersed DOPO has little impact on the mechanical properties of the substrate. The branched butyl ester short chains, acting as flexible spacer segments, reduce stress concentration and form a uniform toughening effect, significantly improving the strength and toughness of the material. Detailed Implementation

[0021] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0022] Example 1: Preparation of environmentally friendly PET materials, as detailed below:

[0023] (1) Preparation of flame retardant recycling agent

[0024] Step A1: Butyl glycolate and anhydrous tetrahydrofuran were mixed, and the air in the reaction system was replaced by dry nitrogen. The temperature was controlled at 0°C in an ice-water bath. 7-Octenyltrichlorosilane was slowly added under stirring and reacted for 2 hours. After returning to room temperature, triethylamine was added and the reaction continued for 0.8 hours. The ratio of 7-octenyltrichlorosilane, butyl glycolate, triethylamine and anhydrous tetrahydrofuran was 10 mmol: 30 mmol: 4.2 mL: 30 mL. After filtration, tetrahydrofuran was removed by rotary evaporation to obtain the modified support.

[0025] Step A2: Mix DOPO and dioxane, then add the modified support and mix. Heat to 45°C, slowly add boron trifluoride ether and stir for 3.5 h. Then reflux for 1.3 h. The ratio of modified support, DOPO, boron trifluoride ether and dioxane is 10 mmol: 10 mmol: 0.1 mL: 40 mL. Wash with water and vacuum dry the precipitate to obtain the flame retardant regenerator.

[0026] (2) Preparation of PET environmentally friendly materials

[0027] Ingredients: 12wt% reinforcing filler, selected from XD-S10H5 type silane-modified silica; 5.8wt% toughening agent, selected from CMG5805 type POE-g-MAH (maleic anhydride grafted POE); 8.2wt% flame retardant regenerator, prepared in this embodiment; 2.4wt% lubricant, selected from KJ-B01 type silicone powder and industrial grade ethylene bis-stearamide in equal weight ratio; 0.13wt% antioxidant, selected from antioxidant 1010 and antioxidant 168 in equal weight ratio; the balance is recycled PET, selected from GL-018085 type granules.

[0028] Melting and granulation: Toughening agent, flame retardant regenerator, lubricant, antioxidant and recycled PET are mixed and fed into the main feed port of the extruder, and reinforcing filler is fed into the side feed port. The temperature of each section of the extruder is set as follows: feeding section (zone 1: 250℃), compression section (zone 2: 260℃, zone 3: 270℃), homogenization section (zone 4: 270℃, zone 5: 270℃), and die section (zone 6: 260℃). After plasticizing and mixing the components, they are extruded and granulated to obtain PET environmentally friendly material.

[0029] Example 2: Preparation of environmentally friendly PET materials, as detailed below:

[0030] (1) Preparation of flame retardant recycling agent

[0031] Step A1: Butyl glycolate and anhydrous tetrahydrofuran were mixed, and the air in the reaction system was replaced by dry nitrogen gas. The temperature was controlled at 5°C in an ice-water bath. 7-Octenyltrichlorosilane was slowly added under stirring and the reaction was carried out for 1.5 h. After returning to room temperature, triethylamine was added and the reaction was continued for 0.5 h. The ratio of 7-octenyltrichlorosilane, butyl glycolate, triethylamine and anhydrous tetrahydrofuran was 10 mmol: 30 mmol: 5.5 mL: 35 mL. After filtration, tetrahydrofuran was removed by rotary evaporation to obtain the modified support.

[0032] Step A2: Mix DOPO and dioxane, then add the modified carrier and mix. Heat to 60°C, slowly add boron trifluoride ether and stir for 2.8 h. Then reflux for 1 h. The ratio of modified carrier, DOPO, boron trifluoride ether and dioxane is 10 mmol: 10 mmol: 0.12 mL: 50 mL. Wash with water and vacuum dry the precipitate to obtain the flame retardant regenerator.

[0033] (2) Preparation of PET environmentally friendly materials

[0034] Ingredients: 16wt% reinforcing filler, selected from XD-S10H5 type silane-modified silica; 4.2wt% toughening agent, selected from CMG5805 type POE-g-MAH (maleic anhydride grafted POE); 10.5wt% flame retardant regenerator, prepared in this embodiment; 3wt% lubricant, selected from KJ-B01 type silicone powder and industrial grade ethylene bis-stearamide in equal weight ratio; 0.17wt% antioxidant, selected from antioxidant 1010 and antioxidant 168 in equal weight ratio; the balance is recycled PET, selected from GL-018085 type granules.

[0035] Melting and granulation: Toughening agent, flame retardant regenerator, lubricant, antioxidant and recycled PET are mixed and fed into the main feed port of the extruder, and reinforcing filler is fed into the side feed port. The temperature of each section of the extruder is set as follows: feeding section (zone 1: 260℃), compression section (zone 2: 270℃, zone 3: 270℃), homogenization section (zone 4: 280℃, zone 5: 285℃), and die section (zone 6: 270℃). After plasticizing and mixing the components, they are extruded and granulated to obtain PET environmentally friendly material.

[0036] Example 3: Preparation of environmentally friendly PET materials, as detailed below:

[0037] (1) Preparation of flame retardant recycling agent

[0038] Step A1: Butyl glycolate and anhydrous tetrahydrofuran were mixed, and the air in the reaction system was replaced by dry nitrogen. The temperature was controlled at 5°C in an ice-water bath. 7-Octenyltrichlorosilane was slowly added under stirring and the reaction was carried out for 1.8 h. After returning to room temperature, triethylamine was added and the reaction was continued for 0.6 h. The ratio of 7-octenyltrichlorosilane, butyl glycolate, triethylamine and anhydrous tetrahydrofuran was 10 mmol:30 mmol:4.8 mL:30 mL. After filtration, tetrahydrofuran was removed by rotary evaporation to obtain the modified support.

[0039] Step A2: Mix DOPO and dioxane, then add the modified carrier and mix. Heat to 55°C, slowly add boron trifluoride ether and stir for 3 hours. Then reflux for 1.1 hours. The ratio of modified carrier, DOPO, boron trifluoride ether and dioxane is 10 mmol: 10 mmol: 0.11 mL: 45 mL. Wash with water and vacuum dry the precipitate to obtain the flame retardant regenerator.

[0040] (2) Preparation of PET environmentally friendly materials

[0041] Ingredients: 14wt% reinforcing filler, selected from XD-S10H5 type silane-modified silica; 5wt% toughening agent, selected from CMG5805 type POE-g-MAH (maleic anhydride grafted POE); 9.4wt% flame retardant regenerator, prepared in this embodiment; 2.6wt% lubricant, selected from KJ-B01 type silicone powder and industrial grade ethylene bis-stearamide in equal weight ratio; 0.15wt% antioxidant, selected from antioxidant 1010 and antioxidant 168 in equal weight ratio; the balance is recycled PET, selected from GL-018085 type granules.

[0042] Melting and granulation: Toughening agent, flame retardant regenerator, lubricant, antioxidant and recycled PET are mixed and fed into the main feed port of the extruder, and reinforcing filler is fed into the side feed port. The temperature of each section of the extruder is set as follows: feeding section (zone 1: 255℃), compression section (zone 2: 260℃, zone 3: 270℃), homogenization section (zone 4: 270℃, zone 5: 280℃), and die section (zone 6: 265℃). After plasticizing and mixing the components, they are extruded and granulated to obtain PET environmentally friendly material.

[0043] Example 4: Preparation of environmentally friendly PET materials, as detailed below:

[0044] (1) Preparation of flame retardant recycling agent

[0045] Step A1: Butyl glycolate and anhydrous tetrahydrofuran were mixed, and the air in the reaction system was replaced by dry nitrogen gas. The temperature was controlled at 0°C in an ice-water bath. 7-Octenyltrichlorosilane was slowly added under stirring and reacted for 2 hours. After returning to room temperature, triethylamine was added and the reaction continued for 0.6 hours. The ratio of 7-octenyltrichlorosilane, butyl glycolate, triethylamine and anhydrous tetrahydrofuran was 10 mmol: 30 mmol: 4.5 mL: 35 mL. After filtration, tetrahydrofuran was removed by rotary evaporation to obtain the modified support.

[0046] Step A2: Mix DOPO and dioxane, then add the modified support and mix. Heat to 50°C, slowly add boron trifluoride ether and stir for 3.2 h. Then reflux for 1.2 h. The ratio of modified support, DOPO, boron trifluoride ether and dioxane is 10 mmol: 10 mmol: 0.1 mL: 50 mL. Wash with water and vacuum dry the precipitate to obtain the flame retardant regenerator.

[0047] (2) Preparation of PET environmentally friendly materials

[0048] Ingredients: 15wt% reinforcing filler, selected from XD-S10H5 type silane-modified silica; 5.3wt% toughening agent, selected from CMG5805 type POE-g-MAH (maleic anhydride grafted POE); 9.8wt% flame retardant regenerator, prepared in this embodiment; 2.7wt% lubricant, selected from KJ-B01 type silicone powder and industrial grade ethylene bis-stearamide in equal weight ratio; 0.15wt% antioxidant, selected from antioxidant 1010 and antioxidant 168 in equal weight ratio; the balance is recycled PET, selected from GL-018085 type granules.

[0049] Melting and granulation: Toughening agent, flame retardant regenerator, lubricant, antioxidant and recycled PET are mixed and fed into the main feed port of the extruder, and reinforcing filler is fed into the side feed port. The temperature of each section of the extruder is set as follows: feeding section (zone 1: 255℃), compression section (zone 2: 265℃, zone 3: 275℃), homogenization section (zone 4: 280℃, zone 5: 280℃), and die section (zone 6: 265℃). After plasticizing and mixing the components, they are extruded and granulated to obtain PET environmentally friendly material.

[0050] Comparative Example 1, referring to Example 4, the flame retardant recycling agent was replaced with DOPO in equal amounts according to the phosphorus content, and the remaining amount was supplemented by toughening agent to 100wt%.

[0051] Comparative Example 2, referring to Example 4, the flame retardant recycling agent was replaced with DOPO-ITA in equal amounts according to the phosphorus content, and the remainder was supplemented by toughening agent to 100wt%.

[0052] The PET environmentally friendly material prepared above was molded into sheet samples using a flat mold at 260℃ and 15MPa. Tensile properties were tested according to ASTM D638-2022 standard, with a test strip size of Type I and a tensile rate of 50mm / min. Impact properties were tested according to ASTM D256-1997 standard. Limiting oxygen index was tested according to ASTM D2863-2023 standard. A 1.6mm thick sample was tested using the vertical burning method according to UL94 standard, recording the burning time and dripping behavior to determine the flame retardancy rating. Specific test results are shown in Table 1.

[0053] Table 1

[0054] Tensile strength / MPa Limiting oxygen index / % <![CDATA[Impact strength kJ·m -2 > UL94 rating Example 1 42.5 31.9 8.9 V-0 Example 2 48.9 33.2 8.2 V-0 Example 3 44.1 32.4 9.1 V-0 Example 4 46.3 32.7 9.5 V-0 Comparative Example 1 37.3 27.9 4.9 V-2 Comparative Example 2 40.7 29.3 6.4 V-2

[0055] In the above tests, the tensile strength and impact strength of the sample from the example were higher than those of the comparative example, demonstrating excellent toughness. The limiting oxygen index of the example was above 31.9%, demonstrating high flame retardancy. In the sustained ignition test, the example reached the V-0 standard, while the comparative example showed obvious dripping, and its flame retardancy level could only meet the V-2 standard.

[0056] In the description of this specification, the references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above 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 one or more embodiments or examples.

[0057] The above description is merely an example and illustration of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described or use similar methods to replace them, as long as they do not deviate from the invention or exceed the scope defined in the claims, they should all fall within the protection scope of the present invention.

Claims

1. A PET environmentally friendly material, characterized in that, The specific composition is as follows: 12-16 wt% reinforcing filler, 4.2-5.8 wt% toughening agent, 8.2-10.5 wt% flame retardant recycling agent, 2.4-3 wt% lubricant, and 0.13-0.17 wt% antioxidant, with the balance being recycled PET; The flame-retardant regenerator is prepared by the following method: Step A1: Mix butyl glycolate and anhydrous tetrahydrofuran, purge the air from the reaction system with dry nitrogen, control the temperature in an ice-water bath at 0-5℃, slowly add 7-octenyltrichlorosilane while stirring, and react for 1.5-2 h. After returning to room temperature, add triethylamine and continue the reaction for 0.5-0.8 h. After filtration, remove tetrahydrofuran by rotary evaporation to obtain the modified support. The ratio of 7-octenyltrichlorosilane, butyl glycolate, triethylamine, and anhydrous tetrahydrofuran is 10 mmol: 30 mmol: 4.2-5.5 mL: 30-35 mL. Step A2: Mix DOPO and dioxane, then add the modified carrier and mix. Heat to 45-60℃, slowly add boron trifluoride ether and stir for 2.8-3.5h. Then reflux for 1-1.3h, wash with water, and vacuum dry the precipitate to obtain the flame retardant regenerator. The ratio of modified carrier, DOPO, boron trifluoride ether and dioxane is 10mmol:10mmol:0.1-0.12mL:40-50mL.

2. The PET environmentally friendly material according to claim 1, characterized in that, The reinforcing filler is silane-modified silica.

3. The PET environmentally friendly material according to claim 1, characterized in that, The toughening agent is POE-g-MAH.

4. The PET environmentally friendly material according to claim 1, characterized in that, The lubricant is a compound of silicone powder and ethylene bis-stearamide.

5. A method for preparing PET environmentally friendly material according to any one of claims 1-4, characterized in that, Specifically, toughening agent, flame retardant recycler, lubricant, antioxidant and recycled PET are mixed and fed into the main feed port of the extruder, and reinforcing filler is fed into the side feed port. After plasticizing and mixing, the mixture is extruded and pelletized to obtain environmentally friendly PET material.

6. The method for preparing a PET environmentally friendly material according to claim 5, characterized in that, The temperatures for each extrusion section during the plasticizing and mixing process are set as follows: feeding section: 250-260℃, compression section: 260-270℃, homogenization section: 270-285℃, and die section: 260-270℃.

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