Halogen-free polyester film and preparation method thereof
By combining ternary composite flame retardants and interface modifiers, the problem of balancing flame retardancy and mechanical properties of polyester films has been solved, achieving high-efficiency flame retardancy and environmental protection performance of halogen-free polyester films, which are suitable for fields such as electronics, electrical appliances and rail transportation.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SHAOXING XIANGYU GREEN PACKING CO LTD
- Filing Date
- 2026-03-04
- Publication Date
- 2026-05-12
AI Technical Summary
Existing polyester films suffer from poor environmental performance and an inability to simultaneously achieve both flame retardancy and mechanical properties. Traditional halogenated flame retardants produce toxic gases upon combustion, and inorganic flame retardants have poor compatibility with the polyester matrix, affecting the film's processing stability and mechanical properties.
A ternary composite flame retardant system is adopted, including aluminum diethylphosphinate, melamine cyanurate and vanillin-derived phosphorus and nitrogen flame retardants, combined with an interface modifier, to form a highly efficient phosphorus-nitrogen synergistic flame retardant effect, rapidly forming a dense charcoal protective layer, improving the interfacial compatibility between the composite flame retardant and the polyester matrix, and enhancing the flame retardancy and mechanical properties of the film.
It achieves a balance between high flame retardancy efficiency and excellent mechanical properties of halogen-free polyester film, improves the environmental friendliness of combustion gases, and achieves a tensile strength of 162.8-177.4 MPa, a limiting oxygen index (LOI) of 26.8-34.7%, and a flame retardancy rating of VTM-0, making it suitable for high-end application scenarios.
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Abstract
Description
Technical Field
[0001] This application relates to the field of plastic film technology, specifically to a halogen-free polyester film and its preparation method. Background Technology
[0002] Polyester film is widely used in electronics, packaging, construction, and other fields due to its excellent mechanical properties, heat resistance, and electrical insulation. However, traditional polyester film is flammable, and it must be modified by adding flame retardants to meet safety requirements.
[0003] Currently, the industry commonly uses halogenated flame retardants (such as bromine compounds) to modify polyester films for flame retardancy. While these flame retardants have high flame retardant efficiency, they release toxic and harmful gases such as dioxins during combustion, seriously endangering human health and the ecological environment. Furthermore, they do not comply with EU RoHS and other environmental regulations, severely limiting their application. In recent years, halogen-free flame retardant technology has become a research hotspot in the flame retardant modification of polyester films. However, existing halogen-free flame retardant systems still suffer from low flame retardant efficiency. To achieve ideal flame retardant effects, a large amount of flame retardant needs to be added. However, inorganic flame retardants have poor compatibility with the polyester matrix, which not only affects the processing stability of the film but also leads to a significant decrease in the film's mechanical properties, making it difficult to meet the comprehensive performance requirements of materials in practical applications.
[0004] Therefore, it is of great significance to develop a halogen-free polyester film that combines high flame retardancy efficiency and excellent mechanical properties. Summary of the Invention
[0005] In order to overcome the problems of poor environmental performance, flame retardancy and mechanical properties of existing polyester films, this application provides a halogen-free polyester film and its preparation method.
[0006] This application provides a halogen-free polyester film, which adopts the following technical solution: A halogen-free polyester film comprises the following raw materials in parts by weight: 60-75 parts of matrix material, 25-40 parts of composite flame retardant, 0.5-1 parts of interface modifier, and 0.5-1 parts of other additives. The composite flame retardant is a phosphorus-nitrogen flame retardant consisting of aluminum diethylphosphonate, melamine cyanurate, and vanillin-derived phosphorus-nitrogen flame retardant in a weight ratio of 3:(0.8-1.5):(1-2).
[0007] This application provides a halogen-free polyester film that, through the selection of the type and ratio of flame retardant, achieves simultaneous improvement in the flame retardancy and mechanical properties of the polyester film. This effectively solves the problems of traditional polyester films struggling to balance flame retardancy and mechanical properties, and the environmental pollution caused by the combustion of halogen-containing flame retardant materials. The resulting halogen-free polyester film can meet the stringent requirements of high-end applications with high comprehensive performance demands. Specifically, this application uses a ternary composite flame retardant system, which can form a highly efficient phosphorus-nitrogen synergistic flame retardant effect. During combustion, the flame retardant can quickly induce the formation of a dense, continuous charcoal protective layer on the film surface, effectively blocking heat transfer and oxygen penetration, and inhibiting the continuous spread of flames and dripping molten material. Simultaneously, this flame retardant system is a halogen-free formulation, fundamentally avoiding the problem of traditional halogen-containing flame retardants producing highly toxic and corrosive gases such as hydrogen halides during combustion. Combined with the environmentally friendly molecular structure of vanillin-derived flame retardants, it significantly reduces the release of toxic and harmful components in combustion flue gas, resulting in a significant improvement in the environmental friendliness of the combustion gases. The addition of interface modifiers can improve the interfacial compatibility between the composite flame retardant and the polyester matrix, solving the problem that high-filler flame retardant content easily leads to the deterioration of film mechanical properties. This ensures that the tensile strength and other mechanical properties of the film remain at ideal levels, achieving good processability and durability. In summary, the film provided in this application achieves a balance between flame retardancy, mechanical properties, and environmental performance, and can be widely used in fields with high requirements for material safety and environmental protection, such as electronics, electrical appliances, and rail transportation, showing great application prospects.
[0008] Optionally, the weight ratio of aluminum diethylphosphonate, melamine cyanurate and vanillin-derived phosphorus nitrogen flame retardant is 3:(1-1.3):(1.5-2).
[0009] Optionally, the weight ratio of aluminum diethylphosphonate, melamine cyanurate, and vanillin-derived phosphorus-nitrogen flame retardant is 3:1:1.5.
[0010] Optionally, the matrix material is polyethylene terephthalate; other additives are selected from antioxidants and lubricants.
[0011] Optionally, the interface modifier is selected from γ-ureidopropyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane, diethylphosphorylethyltriethoxysilane, and 2-(diphenylphosphino)ethyltriethoxysilane.
[0012] Optionally, the interface modifier is 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane and 2-(diphenylphosphino)ethyltriethoxysilane in a weight ratio of 1:(1.5-3).
[0013] Optionally, the halogen-free polyester film has a thickness of 20-30 μm, a tensile strength ≥160 MPa, a limiting oxygen index (LOI) ≥25%, and a flame retardant rating of VTM-0.
[0014] Secondly, this application provides a method for preparing a halogen-free polyester film, comprising the following steps: adding a composite flame retardant, an interface modifier, and other additives to a matrix material and stirring and premixing; then forming a preform film by melt blending and extrusion; and finally obtaining a halogen-free polyester film by biaxial stretching and heat setting. The longitudinal stretching temperature of the biaxially stretched film is 95±5℃, and the transverse stretching temperature is 110±5℃; the longitudinal / transverse stretching ratio is (3-4):1; and the heat setting temperature is 180-220℃.
[0015] Optionally, the melt blending and extrusion are carried out using a twin-screw extruder; the temperatures of each zone are 255±5℃, 265±5℃, 270±5℃, and 275±5℃, respectively.
[0016] In summary, this application has the following beneficial effects: 1. This application uses aluminum diethylphosphonate, melamine cyanurate and vanillin-derived phosphorus-nitrogen flame retardant in a weight ratio of 3:(0.8-1.5):(1-2) as a composite flame retardant. By compounding it with matrix materials, interface modifiers and other materials, a halogen-free polyester film with good environmental protection, good flame retardancy and excellent mechanical properties can be prepared, which can meet the requirements of practical applications for the comprehensive performance of materials.
[0017] 2. The halogen-free polyester film obtained in this application has a tensile strength of 162.8-177.4 MPa, a limiting oxygen index (LOI) of 26.8-34.7%, and a flame retardant rating of VTM-0.
[0018] 3. The present application further uses 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane and 2-(diphenylphosphino)ethyltriethoxysilane in a weight ratio of 1:(1.5-3) as interface modifiers, which enables the tensile strength of the obtained halogen-free polyester film to reach 171.3-177.4 MPa. Detailed Implementation
[0019] This application provides a halogen-free polyester film comprising the following raw materials in parts by weight: 60-75 parts of matrix material, 25-40 parts of composite flame retardant, 0.5-1 parts of interface modifier, 0.3-0.5 parts of antioxidant, and 0.2-0.5 parts of lubricant; wherein the composite flame retardant is aluminum diethylphosphonate, melamine cyanurate, and vanillin-derived phosphorus-nitrogen flame retardant in a weight ratio of 3:(0.8-1.5):(1-2); further, the weight ratio of aluminum diethylphosphonate, melamine cyanurate, and vanillin-derived phosphorus-nitrogen flame retardant is 3:(1-1.3):(1.5-2). The interface modifier is selected from γ-ureidopropyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane, diethylphosphonoethyltriethoxysilane, and 2-(diphenylphosphino)ethyltriethoxysilane; further, the interface modifier is 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane and 2-(diphenylphosphino)ethyltriethoxysilane in a weight ratio of 1:(1.5-3).
[0020] This application also provides a method for preparing the above-mentioned halogen-free polyester film, comprising the following steps: (1) Add composite flame retardant, interface modifier and other additives to the matrix material and stir to premix; (2) Next, a twin-screw extruder is used to melt-blend and extrude the premix to form a preform; the temperatures of each zone of the twin-screw extruder are 255±5℃, 265±5℃, 270±5℃ and 275±5℃ respectively.
[0021] (3) Finally, the preform film is biaxially stretched into a film and heat-set to obtain a halogen-free polyester film; wherein, the longitudinal stretching temperature of biaxially stretched film is 95±5℃, the transverse stretching temperature is 110±5℃; the longitudinal / transverse stretching ratio is (3-4):1; and the heat setting temperature is 180-220℃.
[0022] In this application, the CAS number of γ-ureidopropyltriethoxysilane is 116912-64-2; the CAS number of 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane is 10217-34-2; the CAS number of diethylphosphorylethyltriethoxysilane is 757-44-8; and the CAS number of 2-(diphenylphosphino)ethyltriethoxysilane is 18586-39-5. The raw materials, reagents, solvents, etc. used in this application can all be obtained by self-production or commercial purchase.
[0023] The following describes this application in further detail with reference to preparation examples, embodiments, and performance testing. Preparation Example 1
[0024] Preparation Example 1 provides a vanillin-derived phosphorus-nitrogen flame retardant.
[0025] The preparation method of the above-mentioned vanillin-derived phosphorus-nitrogen flame retardant includes the following steps: (1) Add 152g vanillin, 126g melamine, 3g p-toluenesulfonic acid and 300mL toluene to a 1L four-necked flask equipped with a stirrer, reflux condenser and oil-water separator (with a small amount of toluene added beforehand); start stirring and heat to 115℃, reflux for 4h; after the reaction is completed, cool down to 60℃, filter and collect the solid product, wash twice with 300mL of 60℃ hot water, and vacuum dry at 60℃ for 8h to obtain the nitrogen-doped intermediate (vanillin-melamine condensate).
[0026] (2) Add the nitrogen-doped intermediate and 200 mL of toluene to a 1 L four-necked flask, heat to 80 °C, and stir until completely dissolved; slowly add 110 g of dimethyl phosphite to the flask using a constant pressure dropping funnel, and add 2.7 g of anhydrous aluminum chloride as a catalyst; after the addition is complete, heat to 105 °C and keep the reaction at this temperature for 6 h; after the reaction is complete, cool to room temperature, slowly pour the reaction solution into 500 mL of ice water, stir to precipitate the solid, filter and collect the precipitate; recrystallize by ethanol, and vacuum dry at 70 °C for 12 h to obtain a white powder of vanillin-derived phosphorus-nitrogen flame retardant. Examples 1-6
[0027] Examples 1-6 each provide a halogen-free polyester film.
[0028] The difference in the above embodiments is that the ratio of the composite flame retardant is as shown in Table 1 below.
[0029] The preparation method of the halogen-free polyester film provided in Examples 1-6 includes the following steps: (1) Add 33.5g of composite flame retardant, 1g of interface modifier γ-ureopropyltriethoxysilane, 0.3g of antioxidant 1010 and 0.2g of lubricant calcium stearate to 65g of polyethylene terephthalate granules, and stir to premix; (2) Next, a twin-screw extruder is used to melt-blend and extrude the premix to form a preform; the temperatures of each zone of the twin-screw extruder are 255℃, 265℃, 270℃ and 275℃ respectively.
[0030] (3) Finally, the preform film is biaxially stretched into a film and heat-set to obtain a halogen-free polyester film with a thickness of 25 μm; wherein, the longitudinal stretching temperature of biaxially stretched film is 95℃, the transverse stretching temperature is 110℃; the longitudinal / transverse stretching ratio is 3.5:1; and the heat setting temperature is 200℃.
[0031] Table 1. Types and proportions of composite flame retardants in Examples 1-6 Examples 7-15
[0032] Examples 7-15 each provide a halogen-free polyester film.
[0033] The difference between the above embodiments and Embodiment 2 lies in the type and ratio of the interface modifier, as shown in Table 2 below.
[0034] Table 2. Types and proportions of interface modifiers in Examples 2 and 7-15 Comparative Example 1
[0035] Comparative Example 1 provides a halogen-free polyester film.
[0036] The difference between the above comparative example and Example 2 is that the composite flame retardant is aluminum hypophosphite, melamine cyanurate and vanillin-derived phosphorus nitrogen flame retardant in a weight ratio of 3:1:1.5. Comparative Example 2
[0037] Comparative Example 2 provides a halogen-free polyester film.
[0038] The difference between the above comparative example and Example 2 is that the composite flame retardant is aluminum diethylphosphonate and vanillin-derived phosphorus-nitrogen flame retardant in a weight ratio of 3:2.5. Comparative Example 3
[0039] Comparative Example 3 provides a halogen-free polyester film.
[0040] The difference between the above comparative example and Example 2 is that the composite flame retardant is aluminum diethylphosphonate and melamine cyanurate in a weight ratio of 3:2.5. Comparative Example 4
[0041] Comparative Example 4 provides a halogen-free polyester film.
[0042] The difference between the above comparative example and Example 2 is that the composite flame retardant is a melamine cyanurate and vanillin-derived phosphorus nitrogen flame retardant in a weight ratio of 2.5:3. Performance testing
[0043] The performance of the halogen-free polyester films obtained in Examples 1-15 and Comparative Examples 1-4 was tested, and the results are shown in Table 3 below.
[0044] (1) Tensile strength: The tensile strength of halogen-free polyester film was tested using a universal testing machine in accordance with GB / T 1040.3-2006 standard.
[0045] (2) Limiting oxygen index: According to GB / T 2406.2-2009 standard, the minimum oxygen concentration required to maintain stable combustion of halogen-free polyester film samples in an oxygen-nitrogen mixed gas flow is determined and expressed as the limiting oxygen index (LOI). (3) Flame retardancy rating: The flame retardancy rating of the halogen-free polyester film samples was tested using the UL94 VTM method.
[0046] Table 3 Performance test results of halogen-free polyester films obtained in Examples 1-15 and Comparative Examples 1-4
[0047] According to the test results in Table 3, the tensile strength of the halogen-free polyester films obtained in Examples 1-15 is 162.8-177.4 MPa, the limiting oxygen index (LOI) is 26.8-34.7%, and the flame retardancy rating is VTM-0. In contrast, the limiting oxygen index (LOI) of the halogen-free polyester films obtained in Comparative Examples 1-4 is only 18.9-21.3%, and the flame retardancy rating is VTM-0 to 1. Therefore, this application demonstrates that by using aluminum diethylphosphonate, melamine cyanurate, and vanillin-derived phosphorus-nitrogen flame retardant in a weight ratio of 3:(0.8-1.5):(1-2) as a composite flame retardant, and by mixing it with matrix materials, interface modifiers, etc., a halogen-free polyester film with good environmental performance, excellent flame retardancy, and superior mechanical properties can be prepared, meeting the requirements of practical applications for the comprehensive performance of materials.
[0048] Although the present invention has been described in detail above with general descriptions and specific embodiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.
Claims
1. A halogen-free polyester film, characterized in that, The raw materials include the following parts by weight: 60-75 parts of matrix material, 25-40 parts of composite flame retardant, 0.5-1 part of interface modifier, and 0.5-1 part of other additives; The composite flame retardant is a phosphorus-nitrogen flame retardant consisting of aluminum diethylphosphonate, melamine cyanurate, and vanillin-derived phosphorus-nitrogen flame retardant in a weight ratio of 3:(0.8-1.5):(1-2).
2. The halogen-free polyester film according to claim 1, characterized in that, The weight ratio of aluminum diethylphosphonate, melamine cyanurate and vanillin-derived phosphorus nitrogen flame retardant is 3:(1-1.3):(1.5-2).
3. The halogen-free polyester film according to claim 1, characterized in that, The weight ratio of aluminum diethylphosphonate, melamine cyanurate, and vanillin-derived phosphorus-nitrogen flame retardant is 3:1:1.
5.
4. The halogen-free polyester film according to claim 1, characterized in that, The matrix material is polyethylene terephthalate; other additives are selected from antioxidants and lubricants.
5. The halogen-free polyester film according to claim 1, characterized in that, The interface modifier is selected from γ-ureidopropyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane, diethylphosphorylethyltriethoxysilane, and 2-(diphenylphosphino)ethyltriethoxysilane.
6. The halogen-free polyester film according to claim 1, characterized in that, The interface modifier is 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane and 2-(diphenylphosphino)ethyltriethoxysilane in a weight ratio of 1:(1.5-3).
7. The halogen-free polyester film according to any one of claims 1-6, characterized in that, The halogen-free polyester film has a thickness of 20-30 μm, a tensile strength ≥160 MPa, a limiting oxygen index (LOI) ≥25%, and a flame retardant rating of VTM-0.
8. The method for preparing the halogen-free polyester film according to any one of claims 1-6, characterized in that, Includes the following steps: Composite flame retardants, interface modifiers, and other additives are added to the matrix material and stirred for premixing; then, a preform film is formed by melt blending and extrusion; finally, a halogen-free polyester film is obtained by biaxial stretching and heat setting. The longitudinal stretching temperature of the biaxially stretched film is 95±5℃, and the transverse stretching temperature is 110±5℃; the longitudinal / transverse stretching ratio is (3-4):1; and the heat setting temperature is 180-220℃.
9. The method for preparing the halogen-free polyester film according to claim 8, characterized in that, The melt blending and extrusion are carried out using a twin-screw extruder; the temperatures of each zone are 255±5℃, 265±5℃, 270±5℃, and 275±5℃, respectively.