Glass fiber modified PET flame-retardant composite material and preparation method thereof
By preparing a mixture of fluorinated DOPO polyester, glass fiber, and polytetrafluoroethylene, a glass fiber modified PET flame-retardant composite material is formed, which solves the problems of poor flame retardancy and insufficient mechanical strength of PET material, and achieves high-efficiency flame retardancy and improved mechanical properties.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- ZHEJIANG LIDE NEW ENVIRONMENTAL PROTECTION MATERIAL CO LTD
- Filing Date
- 2026-03-18
- Publication Date
- 2026-05-12
AI Technical Summary
PET materials have poor flame retardancy, exhibit dripping during combustion, which affects mechanical strength, and adding polytetrafluoroethylene alone is unlikely to effectively improve flame retardancy.
Fluorinated DOPO polyester was prepared, mixed with glass fiber and polytetrafluoroethylene, and extruded and granulated using a twin-screw extruder to form a glass fiber modified PET flame-retardant composite material. The compatibility of the fluorinated DOPO polyester and the flame-retardant groups of phosphate esters were used to improve the flame-retardant properties and mechanical strength of PET.
It achieves excellent flame retardant properties and good mechanical strength in PET materials, improves the limiting oxygen index, reaches UL-94 V-1 to V-0 level, and maintains good tensile strength.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of PET technology, specifically to a glass fiber modified PET flame-retardant composite material and its preparation method. Background Technology
[0002] Polyethylene terephthalate (PET) is a high-performance resin with high mechanical strength, high modulus, good high-temperature resistance, and biodegradability, and is widely used in fiber, packaging, electronics, and automotive manufacturing. However, PET has poor flame retardancy and exhibits severe dripping during combustion, which can cause burns and secondary disasters. Therefore, flame retardant modification of PET is a key research focus.
[0003] Flame retardants for PET mainly include inorganic flame retardants such as antimony trioxide, and organic flame retardants such as phosphorus-based and nitrogen-based flame retardants. Polytetrafluoroethylene (PTFE) has strong high-temperature resistance and preferentially depolymerizes into smaller molecules during high temperatures or combustion, without forming molten droplets. It is a common anti-dripping agent and has important applications in flame retardant materials. However, PTFE has poor compatibility with PET, which affects the mechanical strength of PET. Furthermore, adding PTFE alone is insufficient to effectively improve the flame retardant properties of PET. Summary of the Invention
[0004] This invention solves the problem of low flame retardancy of PET materials while maintaining good mechanical strength.
[0005] The technical solution of this invention is: a method for preparing glass fiber modified PET flame-retardant composite material: (1) Thionyl chloride and 2,2-bis(4-carboxyphenyl)hexafluoropropane were added to the reaction vessel, the mixture was stirred, concentrated under reduced pressure, and the product was recrystallized in n-hexane to obtain 2,2-bis(4-formylchlorophenyl)hexafluoropropane. The reaction formula is: .
[0006] (2) Nitrogen gas was introduced into the reaction flask, followed by the addition of solvent, acid-binding agent, and 10-(2,5-dihydroxyphenyl)-9,10-dihydro-9-oxa-10-phosphenanthroline-10-oxide. After stirring, 2,2-bis(4-formylchlorophenyl)hexafluoropropane was added in an ice bath, and the reaction was stirred. Water was added for dilution, and the product was filtered, washed with water and ethanol, and dried to obtain fluorinated DOPO polyester. The reaction formula is: .
[0007] (3) Polyethylene terephthalate, glass fiber, polytetrafluoroethylene and fluorinated DOPO polyester are mixed and then extruded through a twin-screw extruder and granulated to obtain glass fiber modified PET flame retardant composite material.
[0008] Furthermore, in (1), the ratio of thionyl chloride to 2,2-bis(4-carboxyphenyl)hexafluoropropane is 1L:(300-360)g.
[0009] Furthermore, in (1), the temperature during the stirring reaction is 75-80℃, and the reaction time is 12-18h.
[0010] Furthermore, in (2), the solvent is N-methylpyrrolidone or N,N-dimethylformamide.
[0011] Furthermore, in (2), the ratio of acid-binding agent, 10-(2,5-dihydroxyphenyl)-9,10-dihydro-9-oxa-10-phosphenanthrene-10-oxide, and 2,2-bis(4-formylchlorophenyl)hexafluoropropane is (2-2.4) mol: (1.02-1.06) mol: 1 mol.
[0012] Furthermore, in (2), the acid-binding agent is triethylamine or pyridine.
[0013] Furthermore, in (2), the temperature during the stirring reaction is 70-90℃ and the reaction time is 6-10h.
[0014] Furthermore, by weight, the amount of polyethylene terephthalate is 100 parts, glass fiber is 30-42 parts, polytetrafluoroethylene is 8-14 parts, and fluorinated DOPO polyester is 2-7 parts.
[0015] Furthermore, in (3), the temperature of each section of the twin-screw extruder is 170-260℃, and the screw speed is 40-100r / min.
[0016] The beneficial technical effects of this invention are as follows: A fluorinated DOPO polyester is obtained by polymerizing 10-(2,5-dihydroxyphenyl)-9,10-dihydro-9-oxa-10-phosphenanthrene-10-oxide and 2,2-bis(4-formylchlorophenyl)hexafluoropropane. This fluorinated DOPO polyester is then mixed with reinforcing agents such as glass fiber, polytetrafluoroethylene (PTFE) anti-drip agent, and polyethylene terephthalate (PET) to obtain a glass fiber-modified PET flame-retardant composite material. The fluorinated DOPO polyester contains polyester molecular chains similar to PET, and also contains multiple fluorinated groups. Its polarity is similar to that of PTFE, which can compatibilize PET and PTFE, improving the compatibility between PTFE and PET, reducing the influence of PTFE on the mechanical properties of PET, and maintaining good tensile strength in the composite material.
[0017] The fluorinated DOPO polyester of the present invention contains phosphate ester flame retardant groups, which have condensed phase flame retardant properties. It works synergistically with polytetrafluoroethylene anti-dripping agent to retard flame, increasing the limiting oxygen index of the material and achieving UL-94 ratings from V-1 to V-0, demonstrating excellent flame retardant performance. Detailed Implementation
[0018] The technical solutions in the embodiments of the present invention will be clearly and completely described below. 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 skilled in the art without creative effort are within the scope of protection of the present invention.
[0019] Example 1: (1) Add 50 mL of thionyl chloride and 15 g of 2,2-bis(4-carboxyphenyl)hexafluoropropane to the reaction vessel, heat to 80 °C, stir and reflux for 12 h, concentrate under reduced pressure, and recrystallize the product in n-hexane to obtain 2,2-bis(4-formylchlorophenyl)hexafluoropropane.
[0020] (2) Nitrogen gas was introduced into the reaction flask, and 600 mL of N,N-dimethylformamide, 200 mmol of triethylamine and 102 mmol of 10-(2,5-dihydroxyphenyl)-9,10-dihydro-9-oxa-10-phosphenanthrene-10-oxide were added. After stirring, 100 mmol of 2,2-bis(4-formylchlorophenyl)hexafluoropropane was added in an ice bath, heated to 80 °C, and stirred for 6 h. Water was added to dilute the product, and after filtration, the product was washed with water and ethanol and dried to obtain fluorinated DOPO polyester.
[0021] (3) Mix 2kg polyethylene terephthalate, 600g glass fiber, 280g polytetrafluoroethylene and 40g fluorinated DOPO polyester, and then extrude them through a twin-screw extruder. The temperatures of each section are 170℃, 235℃, 255℃, 260℃ and 255℃, and the screw speed is 60r / min. Granulate to obtain glass fiber modified PET flame retardant composite material.
[0022] Example 2: (1) Add 50 mL of thionyl chloride and 18 g of 2,2-bis(4-carboxyphenyl)hexafluoropropane to the reaction vessel, heat to 75 °C, stir and reflux for 12 h, concentrate under reduced pressure, and recrystallize the product in n-hexane to obtain 2,2-bis(4-formylchlorophenyl)hexafluoropropane.
[0023] (2) Nitrogen gas was introduced into the reaction flask, and 700 mL of N-methylpyrrolidone, 220 mmol of pyridine, and 106 mmol of 10-(2,5-dihydroxyphenyl)-9,10-dihydro-9-oxa-10-phosphenanthrene-10-oxide were added. After stirring, 100 mmol of 2,2-bis(4-formylchlorophenyl)hexafluoropropane was added in an ice bath. The mixture was heated to 70 °C and stirred for 10 h. Water was added to dilute the mixture, and the product was washed with water and ethanol after filtration and dried to obtain fluorinated DOPO polyester.
[0024] (3) Mix 2kg polyethylene terephthalate, 680g glass fiber, 240g polytetrafluoroethylene and 70g fluorinated DOPO polyester, and then extrude them through a twin-screw extruder. The temperatures of each section are 170℃, 235℃, 255℃, 260℃ and 255℃, and the screw speed is 40r / min. Granulate to obtain glass fiber modified PET flame retardant composite material.
[0025] Example 3: (1) 2,2-bis(4-formylchlorophenyl)hexafluoropropane was prepared according to the method of Example 1.
[0026] (2) Nitrogen gas was introduced into the reaction flask, and 600 mL of N,N-dimethylformamide, 240 mmol of pyridine and 104 mmol of 10-(2,5-dihydroxyphenyl)-9,10-dihydro-9-oxa-10-phosphenanthrene-10-oxide were added. After stirring, 100 mmol of 2,2-bis(4-formylchlorophenyl)hexafluoropropane was added in an ice bath, heated to 80 °C, and stirred for 9 h. Water was added to dilute the product, and after filtration, the product was washed with water and ethanol and dried to obtain fluorinated DOPO polyester.
[0027] (3) Mix 2kg polyethylene terephthalate, 760g glass fiber, 200g polytetrafluoroethylene and 100g fluorinated DOPO polyester, and then extrude them through a twin-screw extruder. The temperatures of each section are 170℃, 235℃, 255℃, 260℃ and 255℃, and the screw speed is 100r / min. Granulate to obtain glass fiber modified PET flame retardant composite material.
[0028] Example 4: (1) 2,2-bis(4-formylchlorophenyl)hexafluoropropane was prepared according to the method of Example 1.
[0029] (2) Nitrogen gas was introduced into the reaction flask, and 700 mL of N,N-dimethylformamide, 220 mmol of triethylamine, and 102 mmol of 10-(2,5-dihydroxyphenyl)-9,10-dihydro-9-oxa-10-phosphenanthrene-10-oxide were added. After stirring, 100 mmol of 2,2-bis(4-formylchlorophenyl)hexafluoropropane was added in an ice bath. The mixture was heated to 90 °C and stirred for 6 h. Water was added to dilute the mixture, and after filtration, the product was washed with water and ethanol and dried to obtain fluorinated DOPO polyester.
[0030] (3) Mix 2 kg of polyethylene terephthalate, 840 g of glass fiber, 160 g of polytetrafluoroethylene and 140 g of fluorinated DOPO polyester, and then extrude them through a twin-screw extruder. The temperatures of each section are 170℃, 235℃, 255℃, 260℃ and 255℃, and the screw speed is 100 r / min. Granulate the mixture to obtain glass fiber modified PET flame retardant composite material.
[0031] Comparative Example 1 differs from Example 1 in that it does not include fluorinated DOPO polyester.
[0032] (1) Mix 2kg polyethylene terephthalate, 600g glass fiber and 280g polytetrafluoroethylene, and then extrude them through a twin-screw extruder. The temperatures of each section are 170℃, 235℃, 255℃, 260℃ and 255℃, and the screw speed is 60r / min. Granulate to obtain glass fiber modified PET composite material.
[0033] Comparative Example 2 differs from Example 1 in that 10-(2,5-dihydroxyphenyl)-9,10-dihydro-9-oxa-10-phosphenanthrene-10-oxide is used instead of the fluorinated DOPO polyester mixture.
[0034] (1) Mix 2 kg of polyethylene terephthalate, 600 g of glass fiber, 280 g of polytetrafluoroethylene, and 40 g of 10-(2,5-dihydroxyphenyl)-9,10-dihydro-9-oxa-10-phosphenanthrene-10-oxide, and then extrude the mixture through a twin-screw extruder at temperatures of 170℃, 235℃, 255℃, 260℃, and 255℃, with a screw speed of 60 r / min, and granulate to obtain glass fiber modified PET composite material.
[0035] Comparative Example 3 differs from Example 1 in that hydroquinone is used instead of 10-(2,5-dihydroxyphenyl)-9,10-dihydro-9-oxa-10-phosphenanthrene-10-oxide.
[0036] (1) Nitrogen gas was introduced into the reaction flask, and 600 mL of N,N-dimethylformamide, 200 mmol of triethylamine and 102 mmol of hydroquinone were added. After stirring, 100 mmol of 2,2-bis(4-formylchlorophenyl)hexafluoropropane was added in an ice bath. The mixture was heated to 80 °C and stirred for 6 h. Water was added to dilute the mixture. After filtration, the product was washed with water and ethanol and dried to obtain fluorinated polyester.
[0037] (2) Mix 2kg polyethylene terephthalate, 600g glass fiber, 280g polytetrafluoroethylene and 40g fluorinated polyester, and then extrude them through a twin-screw extruder. The temperatures of each section are 170℃, 235℃, 255℃, 260℃ and 255℃, and the screw speed is 60r / min. Granulate to obtain glass fiber modified PET composite material.
[0038] Comparative Example 4 differs from Example 1 in that 2,2-bis(4-formylchlorophenyl)hexafluoropropane is replaced with 4,4'-biphenyldicarboxylic acid chloride (CAS No. 2351-37-3).
[0039] (1) Nitrogen gas was introduced into the reaction flask, and 600 mL of N,N-dimethylformamide, 200 mmol of triethylamine and 102 mmol of 10-(2,5-dihydroxyphenyl)-9,10-dihydro-9-oxa-10-phosphenanthrene-10-oxide were added. After stirring, 100 mmol of 4,4'-biphenyldicarboxylic acid chloride was added in an ice bath, heated to 80 °C, and stirred for 6 h. Water was added to dilute the product, and after filtration, the product was washed with water and ethanol and dried to obtain DOPO polyester.
[0040] (2) Mix 2kg polyethylene terephthalate, 600g glass fiber, 280g polytetrafluoroethylene and 40g DOPO polyester, and then extrude them through a twin-screw extruder. The temperatures of each section are 170℃, 235℃, 255℃, 260℃ and 255℃, and the screw speed is 60r / min. Granulate to obtain glass fiber modified PET composite material.
[0041] PET composite materials were injection molded into test strips. The oxygen index was tested according to GB / T 2406.1-2008, and the vertical burning performance was tested according to the UL-94 method. Tensile strength was tested according to GB / T 1040.1-2018.
[0042] Table 1 Properties of PET composite materials Comparative Example 1 involved blending and granulating polyethylene terephthalate (PET), anti-drip agent polytetrafluoroethylene (PTFE), and glass fiber reinforcement. The resulting glass fiber modified PET composite material exhibited low tensile strength, primarily due to the poor compatibility between PTFE and PET, which affected the mechanical strength of PET. Furthermore, the composite material had a low limiting oxygen index, with a UL-94 rating of only V-2, indicating poor flame retardancy.
[0043] The composite materials in Examples 1-4 incorporated fluorinated DOPO polyester, which contains polyester molecular chains similar to PET and multiple fluorinated groups. Its polarity is similar to that of polytetrafluoroethylene (PTFE), thus acting as a compatibilizer for both PET and PTFE. This improves the compatibility between PTFE and PET, reduces the impact of PTFE on the mechanical properties of PET, and maintains good tensile strength in the composite material. Furthermore, the fluorinated DOPO polyester contains phosphate ester flame-retardant groups, exhibiting condensed-phase flame-retardant properties. It synergistically enhances the flame-retardant effect with the PTFE anti-dripping agent, significantly improving the flame-retardant performance of the material. The limiting oxygen index increases, achieving UL-94 ratings from V-1 to V-0.
[0044] The 10-(2,5-dihydroxyphenyl)-9,10-dihydro-9-oxa-10-phosphenanthrene-10-oxide added in Comparative Example 2 has low compatibility with PET and cannot compatibilize PET and polytetrafluoroethylene, resulting in very low tensile strength of the PET composite material.
[0045] Comparative Example 3: Fluorinated polyester does not contain DOPO phosphate flame-retardant groups, and the PET composite material has a low limiting oxygen index and poor flame retardancy.
[0046] The DOPO polyester in Comparative Example 4 does not contain fluorine, and therefore cannot compatibilize PET and polytetrafluoroethylene, resulting in a significantly lower tensile strength of the PET composite material compared to Example 1.
[0047] The above description is merely an example and illustration of the concept 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 concept of 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 glass fiber modified PET flame-retardant composite material, characterized in that, By weight, the glass fiber modified PET flame retardant composite material comprises 100 parts polyethylene terephthalate, 30-42 parts glass fiber, 8-14 parts polytetrafluoroethylene, and 2-7 parts fluorinated DOPO polyester. The fluorinated DOPO polyester was prepared by the following method: nitrogen gas was introduced into a reaction flask, and solvent, acid-binding agent, and 10-(2,5-dihydroxyphenyl)-9,10-dihydro-9-oxa-10-phosphenanthrene-10-oxide were added. After stirring, 2,2-bis(4-formylchlorophenyl)hexafluoropropane was added in an ice bath, and the reaction was stirred. Water was added to dilute the product, and the product was washed after filtration and dried to obtain the fluorinated DOPO polyester.
2. The glass fiber modified PET flame-retardant composite material according to claim 1, characterized in that, The solvent is N-methylpyrrolidone or N,N-dimethylformamide.
3. The glass fiber modified PET flame-retardant composite material according to claim 1, characterized in that, The ratio of the acid-binding agent, 10-(2,5-dihydroxyphenyl)-9,10-dihydro-9-oxa-10-phosphenanthrene-10-oxide, and 2,2-bis(4-formylchlorophenyl)hexafluoropropane is (2-2.4) mol:(1.02-1.06) mol:1 mol.
4. The glass fiber modified PET flame-retardant composite material according to claim 3, characterized in that, The acid-binding agent is triethylamine or pyridine.
5. The glass fiber modified PET flame-retardant composite material according to claim 1, characterized in that, The temperature during the stirring reaction is 70-90℃, and the reaction time is 6-10h.
6. The glass fiber modified PET flame-retardant composite material according to claim 1, characterized in that, The 2,2-bis(4-formylchlorophenyl)hexafluoropropane was prepared by the following method: thionyl chloride and 2,2-bis(4-carboxyphenyl)hexafluoropropane were added to a reaction vessel, heated to 75-80°C, stirred and refluxed for 12-18 h, concentrated under reduced pressure, and the product was recrystallized to obtain 2,2-bis(4-formylchlorophenyl)hexafluoropropane.
7. The glass fiber modified PET flame-retardant composite material according to claim 6, characterized in that, The ratio of thionyl chloride to 2,2-bis(4-carboxyphenyl)hexafluoropropane is 1L:(300-360)g.
8. A method for preparing a glass fiber modified PET flame-retardant composite material as described in any one of claims 1-7, characterized in that, The preparation method is as follows: polyethylene terephthalate, glass fiber, polytetrafluoroethylene, and fluorinated DOPO polyester are mixed, and then extruded through a twin-screw extruder and granulated to obtain glass fiber modified PET flame retardant composite material.
9. The method for preparing the glass fiber modified PET flame-retardant composite material according to claim 8, characterized in that, The temperature of each section of the twin-screw extruder is 170-260℃, and the screw speed is 40-100 r / min.