Flame-retardant BOPET film

Abstract

The invention relates to the technical field of plastic film production and processing, in particular to a flame-retardant BOPET film which comprises a BOPET base film. The BOPET base film is prepared from the following raw materials: a flame-retardant toughening agent; the flame-retardant toughening agent is prepared by taking terephthalic acid, ethylene glycol, antimony trioxide, trimethyl phosphate and a functional flame-retardant polymer as raw materials; the functional flame-retardant polymer is phosphate with a composite phosphorus structure. According to the flame-retardant BOPET film provided by the invention, the flame-retardant toughening agent is introduced into the base film, so that the flame-retardant property of the BOPET film can be remarkably improved under the condition of keeping good mechanical properties, and the requirements of high-end electronic and electrical and new energy automobile interior lamp scenes on safety materials are met.

Description

Technical Field

[0001] This invention relates to the field of plastic film production and processing technology, and in particular to a flame-retardant BOPET film. Background Technology

[0002] BOPET (biaxially oriented polyester) film is widely used in various fields such as electronic and electrical insulation, packaging materials, industrial substrates, architectural decoration, and optical display devices due to its excellent mechanical strength, dimensional stability, chemical resistance, high transparency, and good electrical insulation properties. In these applications, especially in the internal components of electronic and electrical equipment, building interior materials, vehicle interiors, and high-end packaging, material safety is paramount, placing clear demands on the flame-retardant properties of the film. In the event of a fire, materials with good flame-retardant properties can effectively slow the spread of flames, inhibit heat release, and reduce the generation of toxic fumes, thereby buying valuable time for evacuation and minimizing property damage.

[0003] However, traditional BOPET film is a flammable material with a low limiting oxygen index (LOI). It is easily ignited by open flames and accompanied by dripping, which not only accelerates the spread of fire, but the drippings may also ignite other items, posing a significant safety hazard.

[0004] Existing flame-retardant BOPET film technologies generally suffer from the problem of not being able to balance excellent flame-retardant performance with comprehensive mechanical properties. Although the addition of many high-efficiency flame retardants can improve the flame-retardant rating, they often have a negative impact on the key mechanical properties of the film. Summary of the Invention

[0005] To address the problem that existing flame-retardant BOPET films struggle to balance flame retardancy and mechanical properties, this invention provides a flame-retardant BOPET film. This BOPET film significantly improves its flame retardancy while maintaining good mechanical properties by introducing a flame-retardant toughening agent into the BOPET base film, thus solving the problem of existing flame-retardant BOPET films struggling to balance flame retardancy and mechanical properties.

[0006] The technical solution adopted by this invention to solve its technical problem is: A flame-retardant BOPET film, comprising a BOPET base film; The raw materials for the BOPET base film include flame retardant toughening agents; The flame retardant toughening agent is prepared using terephthalic acid, ethylene glycol, antimony trioxide, trimethyl phosphate, and functional flame retardant polymers as raw materials. The functional flame-retardant polymer is a phosphate with a complex phosphorus structure.

[0007] Optionally, the functional flame-retardant polymer is prepared by the following method: S201: heating the flame-retardant intermediate at 130-150℃ until melting, adding 2,2'-diallyl bisphenol A under stirring to react, and obtaining a crude flame-retardant monomer; S202: dissolving the crude flame-retardant monomer in a solvent, washing under stirring at 90-100℃, and drying under vacuum at 180-190℃ to obtain a refined flame-retardant monomer; S203: mixing dichloromethane, the refined flame-retardant monomer, and N,N-diethylethanamine, stirring until dissolving, and adding phenyldichlorophosphine dropwise to obtain a mixed solution; S204: incubating the mixed solution under inert gas atmosphere at 40-45℃ to react, extracting with petroleum ether, and drying at 50-60℃ to obtain a functional flame-retardant polymer; The flame-retardant intermediate is a substance containing biphenyl ring and phenanthrene ring structure.

[0008] Optionally, the flame-retardant intermediate is 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide.

[0009] Optionally, the flame-retardant intermediate is added in an amount of 8-16 parts by weight, and the 2,2'-diallyl bisphenol A is added in an amount of 4-8 parts by weight in step S201.

[0010] Optionally, the dichloromethane is added in an amount of 50-100 parts by weight, the refined flame-retardant monomer is added in an amount of 37-74 parts by weight, the N,N-diethylethanamine is added in an amount of 5-10 parts by weight, and the phenyldichlorophosphine is added in an amount of 10-20 parts by weight in step S203.

[0011] Optionally, the flame-retardant toughening agent is prepared by the following method: S101: using terephthalic acid, ethylene glycol, antimony trioxide, trimethyl phosphate, and functional flame-retardant dispersion liquid as raw materials, performing first-stage incubation reaction under inert gas protection atmosphere at 200-240℃ and 0.5-0.7Mpa to obtain reaction mixture I; S102: increasing the temperature to 240-260℃ to perform second-stage incubation reaction, and obtaining reaction mixture II; S103: reducing the pressure to 200-300Pa, increasing the temperature to 260-270℃ to perform third-stage incubation reaction, and obtaining reaction mixture III; S104: removing small molecular impurities in the reaction mixture III by distillation, and obtaining the flame-retardant toughening agent by melt extrusion granulation; The functional flame-retardant dispersion liquid is prepared from the functional flame-retardant polymer, ethylene glycol and dispersant by mixing and dispersion.

[0012] Optionally, the terephthalic acid is added in an amount of 1040 parts by weight; the ethylene glycol is added in an amount of 450-650 parts by weight; the antimony trioxide is added in an amount of 0.5-1.0 parts by weight; the trimethyl phosphate is added in an amount of 0.5-1.0 parts by weight; and the functional flame-retardant dispersion liquid is added in an amount of 100-200 parts by weight.

[0013] Optionally, the functional flame-retardant polymer is added in an amount of 10-20 parts by weight; the ethylene glycol is added in an amount of 80-90 parts by weight; and the dispersant is added in an amount of 3-5 parts by weight.

[0014] Optionally, the flame-retardant BOPET film further comprises a functional coating coated on the surface of the BOPET base film. The functional coating is prepared by coating a composite flame-retardant coating on the surface of the BOPET base film. The composite flame-retardant coating is prepared from a resin base liquid, a surface flame-retardant agent A and a surface flame-retardant agent B. The surface flame-retardant agent A is prepared by the following method. S401: adding deionized water to the montmorillonite, stirring, and then adding polyvinyl alcohol to continue stirring to obtain a flame-retardant premix A; S402: adding pentanediol to the flame-retardant premix A and ultrasonically treating, and then drying at 60-80℃ to obtain the surface flame-retardant agent A. The surface flame-retardant agent B is prepared by the following method. S501: mixing dichloromethane, an acyl halide compound and triethylamine to obtain a flame-retardant premix B; S502: mixing dichloromethane and a phosphonate compound, and then adding dropwise to the flame-retardant premix B at 0-5℃, and then reacting at 30-35℃ after the dropwise addition is completed to obtain a flame-retardant liquid B; S503: extracting the flame-retardant liquid B with deionized water, and then drying at 60-80℃ to obtain the surface flame-retardant agent B.

[0015] Optionally, the acyl halide compound is adipoyl chloride; and the phosphonate compound is diethyl hydroxymethyl phosphonate.

[0016] The present application has the following advantages: The flame-retardant BOPET film provided by the application can significantly improve the flame-retardant performance of the BOPET film while maintaining good mechanical properties, so as to meet the requirements of high-end electronic and electrical products and new energy automobile interior lighting scenes for safety materials. BRIEF DESCRIPTION OF DRAWINGS

[0017] The application will be further described below in combination with the drawings and examples.

[0018] Figure 1 is a structural schematic diagram of the BOPET film in the application. DETAILED DESCRIPTION

[0019] The application will now be further described in detail. The examples described below are exemplary and are intended to explain the application, and cannot be understood as a limitation of the application. Based on the examples of the application, all other examples obtained by those of ordinary skill in the art without creative labor fall within the scope of protection of the application.

[0020] The flame-retardant modification of the current BOPET film mainly depends on the addition of flame-retardant fillers or additives in the PET matrix. In order to meet the stringent requirements of high-end electronic and electrical fields for material safety, the BOPET film needs to have excellent flame-retardant properties such as high limiting oxygen index and UL94 high level. However, in order to achieve the above flame-retardant effect, the prior art often needs to introduce a high content of flame retardant into the system. Such flame retardants as heterogeneous components will destroy the uniformity of the PET matrix, hinder the formation of highly oriented molecular chains and crystalline structure, and at the same time, due to their inherent brittleness, poor compatibility with the matrix, and the dilution effect and stress concentration effect caused by high addition amount, the tensile strength and elongation at break of the material are significantly weakened. This strong correlation between the improvement of flame-retardant performance and the deterioration of mechanical properties makes it difficult for the film to balance the flame-retardant property and mechanical bearing capacity, which seriously restricts its application in reliability-sensitive scenarios.

[0021] Based on this, in order to solve the problem that the BOPET film in the prior art is difficult to balance the flame-retardant performance and the mechanical property, the application provides a flame-retardant BOPET film, as shown in Figure 1 The flame-retardant BOPET film includes a BOPET base film; in order to give the BOPET film flame-retardant performance, the raw material of the BOPET base film preferably includes a flame-retardant toughening agent; in order to improve the flame-retardant performance of the BOPET film without losing its mechanical properties, the flame-retardant toughening agent is preferably prepared from terephthalic acid, ethylene glycol, antimony trioxide, trimethyl phosphate, and a functional flame-retardant polymer.

[0022] The diantimony trioxide is introduced as a catalyst to activate the reaction intermediate, promote the polycondensation reaction, optimize the molecular weight, and improve the mechanical strength and thermal stability of the PET.

[0023] The functional flame-retardant polymer is preferably a phosphate with a composite phosphorus structure, which achieves the flame-retardant effect by virtue of its high phosphorus content, catalyzes the dehydration and crosslinking of the PET matrix upon thermal decomposition to form a dense and stable intumescent carbon layer that insulates oxygen and heat, thereby achieving the flame-retardant effect, and the phosphorus element participates in the formation of a crosslinked network to enhance the barrier integrity.

[0024] Specifically, the preferred BOPET base film comprises a polyester core layer and polyester surface layers co-extruded on the upper and lower surfaces of the polyester core layer; further preferably, the polyester surface layer comprises the following components by weight fraction: Opening masterbatch 10-15 parts; PET polyester chip 75-85 parts; Flame-retardant toughening agent 5-10 parts; The polyester core layer comprises the following components by weight fraction: PET polyester chip 90-95 parts; Flame-retardant toughening agent 5-10 parts.

[0025] The flame-retardant BOPET film provided by the present application can significantly improve the flame-retardant performance of the BOPET film while maintaining good mechanical properties, thereby meeting the requirements of high-end electronics and electrical appliances and new energy vehicle interior lighting scenarios for safety materials.

[0026] Further, based on the use demand for high-performance safety materials in many fields such as high-end electronics and electrical appliances, the excellent flame-retardant performance and comprehensive mechanical properties of the BOPET film are taken into account to make it have excellent comprehensive performance, and the opening masterbatch in the polyester surface layer is preferably Yizheng Chemical Fiber FG610 chip; the PET polyester chip in the polyester surface layer and the polyester core layer is Yizheng Chemical Fiber FG600 chip.

[0027] The preferred functional flame-retardant polymer is prepared according to the following method: S201: Heat the flame retardant intermediate to 130-150℃ until it melts, and then add 2,2'-diallyl bisphenol A under stirring to obtain a crude flame retardant monomer after reaction; This step can be performed according to the following process: Heat the flame retardant intermediate to 130-150℃ in an oil bath until it completely melts, and then add 2,2'-diallyl bisphenol A under stirring to obtain a crude flame retardant monomer after reaction; S202: dissolving the crude flame-retardant monomer in a solvent, stirring and washing at a temperature of 90-100℃, and drying under vacuum at 180-190℃ to obtain a refined flame-retardant monomer; Preferably, the solvent in this step is a mixture of ethanol and deionized water, and preferably, the amount of ethanol added is 100-120 parts by weight, and the amount of deionized water added is 300-360 parts by weight; This step can be carried out according to the following process: Dissolve the crude flame-retardant monomer in 100-120 parts by weight of ethanol and 300-360 parts by weight of deionized water, stir and wash at a temperature of 90-100℃ for 30-45 minutes to remove impurities in the crude flame-retardant monomer, repeat the washing 4-5 times, and dry under vacuum at 180-190℃ to obtain a refined flame-retardant monomer after the solvent is completely evaporated; S203: mixing dichloromethane, refined flame-retardant monomer and N,N-diethyl ethylamine, stirring until dissolved, and then adding phenyl dichlorophosphine dropwise to obtain a mixed solution; This step can be carried out according to the following process: Add dichloromethane to a three-necked flask, and add the refined flame-retardant monomer and N,N-diethyl ethylamine described above, stir until completely dissolved, and then slowly add phenyl dichlorophosphine dropwise to obtain a mixed solution; S204: incubating the mixed solution at a temperature of 40-45℃ under an inert gas atmosphere, extracting with petroleum ether, and drying at a temperature of 50-60℃ to obtain a functional flame-retardant polymer; This step can be carried out according to the following process: Incubate the mixed solution at a temperature of 40-45℃ under a nitrogen atmosphere for 4-5 hours, extract with petroleum ether after the reaction is completed, and fully dry at a temperature of 50-60℃ to obtain a functional flame-retardant polymer; Preferably, the flame retardant intermediate in the present application is a substance containing a biphenyl ring and a phenanthrene ring structure.

[0028] Further, preferably, the flame retardant intermediate in the present application is 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide.

[0029] Specifically, preferably, the amount of flame retardant intermediate added in step S201 is 8-16 parts by weight, and the amount of 2,2'-diallyl bisphenol A added is 4-8 parts by weight; preferably, the amount of dichloromethane added in step S203 is 50-100 parts by weight; the amount of refined flame-retardant monomer added is 37-74 parts by weight; the amount of N,N-diethyl ethylamine added is 5-10 parts by weight; and the amount of phenyl dichlorophosphine added is 10-20 parts by weight.

[0030] Specifically, the chemical reaction of step S201 is shown in the following formula: ; The chemical reaction of step S204 is shown in the following formula: ; Wherein, the value range of n is 20-200.

[0031] The present application further introduces the flame-retardant component into the system by the way of preparing the flame-retardant toughening agent with terephthalic acid, ethylene glycol, antimony trioxide, trimethyl phosphate and functional flame-retardant polymer as raw materials, which helps to improve the flame-retardant performance and mechanical properties of the film.

[0032] The preferred flame-retardant toughening agent of the present application is prepared by the following method: S101: with terephthalic acid, ethylene glycol, antimony trioxide, trimethyl phosphate and functional flame-retardant dispersion liquid as raw materials, under the protection of inert gas atmosphere, at 200-240℃, 0.5-0.7Mpa, the first stage of heat preservation reaction is carried out to obtain reaction mixture I; This step can be carried out according to the following process: The terephthalic acid, ethylene glycol, antimony trioxide, trimethyl phosphate and functional flame-retardant dispersion liquid are added into the reaction kettle, and the temperature of the reaction kettle is raised to 200-240℃ under the protection of nitrogen atmosphere, and the pressure is raised to 0.5-0.7Mpa, and the temperature is kept for 60-90min; S102: the temperature is raised to 240-260℃, and the second stage of heat preservation reaction is carried out to obtain reaction mixture II; This step can be carried out according to the following process: The temperature in the reaction kettle is raised to 240-260℃, and the temperature is kept for 90-135min; S103: the pressure is reduced to 200-300Pa, and then the temperature is raised to 260-270℃, and the third stage of heat preservation reaction is carried out to obtain reaction mixture III; This step can be carried out according to the following process: The pressure in the reaction kettle is reduced to 200-300Pa, and then the temperature in the reaction kettle is raised to 260-270℃, and the temperature is kept for 150-180min; S104: small molecular impurities in the reaction mixture III are removed by distillation, and the flame-retardant toughening agent is obtained by melt extrusion granulation; The flame-retardant toughening agent obtained by the present application has a viscosity of 0.650-0.700dL / g, a melting point of 250-270℃, an average molecular weight of 30000-35000, and a functional flame-retardant polymer mass percentage of 0.5-1.0%.

[0033] The functional flame-retardant dispersion liquid is prepared by mixing and dispersing a functional flame-retardant polymer, ethylene glycol and a dispersant.

[0034] To improve the dispersion uniformity, the dispersant is preferably polyethylene glycol.

[0035] The present application introduces the functional flame-retardant polymer into the flame-retardant toughening agent in the form of the functional flame-retardant dispersion liquid, and then the flame-retardant toughening agent and the above components synergistically act to effectively improve the flame-retardant performance and comprehensive mechanical properties of the BOPET film.

[0036] Specifically, the terephthalic acid is added in an amount of 1040 parts by weight, the ethylene glycol is added in an amount of 450-650 parts by weight, the antimony trioxide is added in an amount of 0.5-1.0 parts by weight, the trimethyl phosphate is added in an amount of 0.5-1.0 parts by weight, and the functional flame-retardant dispersion liquid is added in an amount of 100-200 parts by weight.

[0037] Further, the functional flame-retardant polymer is added in an amount of 10-20 parts by weight, the ethylene glycol is added in an amount of 80-90 parts by weight, and the dispersant is added in an amount of 3-5 parts by weight.

[0038] Specifically, the functional flame-retardant dispersion liquid is prepared as follows: Specifically, the terephthalic acid is added in an amount of 1040 parts by weight, the ethylene glycol is added in an amount of 450-650 parts by weight, the antimony trioxide is added in an amount of 0.5-1.0 parts by weight, the trimethyl phosphate is added in an amount of 0.5-1.0 parts by weight, and the functional flame-retardant dispersion liquid is added in an amount of 100-200 parts by weight.

[0039] The functional flame-retardant dispersion liquid prepared by the above method helps to improve the uniformity of the dispersion of the functional flame-retardant polymer in the system, improve the compatibility of the functional flame-retardant polymer with the system, and further help to synergistically act with other components in the system to improve the performance of the film.

[0040] To further improve the flame-retardant performance without sacrificing the mechanical properties, the flame-retardant BOPET film further comprises a functional coating coated on the surface of the BOPET base film; the functional coating is prepared by coating a composite flame-retardant coating on the surface of the BOPET base film; and the composite flame-retardant coating is prepared by using a resin base liquid, a surface flame-retardant agent A and a surface flame-retardant agent B as raw materials.

[0041] To ensure the flame-retardant performance of the BOPET film, the composite flame-retardant coating is preferably a water-based composite flame-retardant coating, and the composite flame-retardant coating is further prepared as follows: S301: 100-150 parts by weight of water-based resin base is added in a stirred tank, 1.0-1.5 parts by weight of wetting and leveling agent, 0.2-1.0 parts by weight of defoaming agent are sequentially added under low-speed stirring at 300-500 rpm, mixed for 10-20 min, to obtain a resin base solution; S302: 1.0-1.5 parts by weight of coupling agent, 2-3 parts by weight of dispersant, 10-20 parts by weight of surface flame retardant A, 10-20 parts by weight of surface flame retardant B are mixed, and dispersed at 2000-3000 rpm for 15-20 min to obtain a surface flame retardant slurry; S303: The surface flame retardant slurry is slowly added to the resin base solution, and kept at medium speed stirring at 600-800 rpm for 20-30 min, then deionized water is added to adjust the viscosity to 100-400 mPas@25℃, and filtered to obtain a composite flame retardant coating.

[0042] Preferably, the water-based resin base is an acrylic emulsion or a polyurethane emulsion (solid content 40±2%); preferably the wetting and leveling agent is selected from at least one of BYK-333, BYK-345, BYK-346; preferably the defoaming agent is selected from at least one of BYK-024, BYK-051, BYK-065; preferably the coupling agent is selected from at least one of KH-550, KH-570; and preferably the dispersant is selected from at least one of BYK-190, BYK-180.

[0043] Preferably, the surface flame retardant A is prepared according to the following method: S401: Deionized water is added to the montmorillonite, stirred, and then polyvinyl alcohol is added and stirred to obtain a flame retardant premix A; This step can be carried out according to the following process: 500-1000 parts by weight of deionized water is added to 5-10 parts by weight of montmorillonite, kept at medium speed stirring at 600-800 rpm for 12-24 h, then 5-10 parts by weight of polyvinyl alcohol is added and stirred for 4-6 h to obtain the flame retardant premix A; S402: Pentanediol is added to the flame retardant premix A, and ultrasonic treatment is carried out, and then dried at 60-80℃ to obtain the surface flame retardant A; This step can be carried out according to the following process: 1-2 parts by weight of pentanediol is added to the flame retardant premix A, and ultrasonic treatment is carried out for 30-60 min, and then fully dried at 60-80℃ to obtain the surface flame retardant A.

[0044] The surface flame retardant A prepared in the application is NMT montmorillonite, and the core mechanism of realizing the flame retardant effect thereof is derived from the unique nanometer layered structure thereof, unique physical flame retardant effect is realized, the NMT montmorillonite can migrate to the outermost layer of the melt during combustion to form a dense ceramic barrier layer, the oxygen diffusion is blocked, the heat conduction is inhibited, and the volatile overflow is blocked, and the flame retardant effect is achieved.

[0045] The surface flame retardant B is prepared according to the following method: S501: dichloromethane, acyl halide compound, triethylamine are mixed to obtain a flame retardant premix B; The step can be carried out according to the following process: 50-100 parts by weight of dichloromethane, 3.5-7.0 parts by weight of acyl halide compound, and 1-2 parts by weight of triethylamine are added to a flask, and after being fully dissolved, a flame retardant premix B is obtained; S502: dichloromethane and phosphonate compound are mixed, and then added dropwise to the flame retardant premix B under the condition of 0-5 DEG C, and after the dropwise addition is completed, the reaction is carried out under the condition of 30-35 DEG C to obtain the flame retardant liquid B; The step can be carried out according to the following process: 50-100 parts by weight of dichloromethane, 3.5-7.0 parts by weight of acyl halide compound, and 1-2 parts by weight of triethylamine are added to a flask, and after being fully dissolved, a flame retardant premix B is obtained; S503: the flame retardant liquid B is extracted with deionized water, and after drying under the condition of 60-80 DEG C, the surface flame retardant B is obtained.

[0046] The acyl halide compound is preferably adipoyl chloride, and the phosphonate compound is preferably diethyl hydroxymethyl phosphonate.

[0047] The reaction process of step S502 of the application is as shown in the following formula: .

[0048] The surface flame retardant B prepared in the application is a halogen-containing organic phosphonate, and the phosphorus-chlorine can realize the flame retardation through a chemical method, the halogen inhibits the free radical reaction, and the phosphorus can inhibit the molten dripping to avoid secondary ignition.

[0049] The application introduces the surface flame retardant A and the surface flame retardant B into the composite flame retardant coating at the same time, realizes high-efficiency flame retardation under the synergistic action of the surface flame retardant A and the surface flame retardant B, and combines the chemical flame retardation and the physical flame retardation method to cover the whole chain of combustion.

[0050] After the composite flame-retardant coating is coated on the surface of the BOPET base film, a composite flame-retardant coating layer is prepared, and through the synergistic effect of the composite flame-retardant coating layer, the polyester surface layer and the polyester core layer, the flame-retardant performance can be improved on the basis of ensuring the comprehensive mechanical properties of the BOPET film.

[0051] The flame-retardant BOPET film provided by the application can significantly improve the flame-retardant performance of the BOPET film while maintaining good mechanical properties through the synergistic effect of the matrix blending modification and the surface functional coating, so as to meet the strict requirements of high-end electronic and electrical products and new energy automobile interior lighting scenes for safety materials.

[0052] The flame-retardant BOPET film provided in the application can be prepared according to the following method: S1: according to the formula amount, the material of the polyester surface layer is transported to the extruder A for melt extrusion; the material of the polyester core layer is transported to the extruder B for melt extrusion; S2: the melt-extruded polyester surface layer material and the polyester core layer material are melt-extruded through a three-layer co-extrusion die head, and an ABA three-layer co-extrusion structure thick sheet is formed by using a rotating cooling roller; S3: the thick sheet is stretched bidirectionally after preheating, the longitudinal stretching is 3.0-3.5 times, and the transverse stretching is 3.0-3.5 times; S4: after the bidirectional stretching of the thick sheet, the thick sheet is heat set at 230-250 DEG C, cooled, drawn, wound and cut, and the BOPET base film is obtained; S5: the composite flame-retardant coating is coated on the surface of the BOPET base film by using the pressure of the coating machine roller and the scraping of the coating knife; S6: the coated BOPET base film is sent into a drying box, and the coating is dried and cured by heating and ventilation, the drying temperature is 160-180 DEG C, and the drying time is 30-60 min; S7: the dried BOPET base film is cooled by a cooling roller, so that the surface temperature is reduced to below room temperature, and the coating is completely cured, and the flame-retardant BOPET film is obtained.

[0053] The application first obtains the flame-retardant BOPET base film through the combination of various materials in the polyester surface layer and the polyester core layer on the basis of ensuring good comprehensive mechanical properties, and then prepares the composite flame-retardant coating on the surface of the flame-retardant BOPET base film by the composite flame-retardant coating, so as to further improve the flame-retardant performance of the BOPET film.

[0054] In order to make the above-mentioned purposes, characteristics and advantages of the application more obvious and easy to understand, the specific embodiments of the application will be described in detail below with reference to the drawings.

[0055] Example 1 The embodiment provides a flame-retardant BOPET film, which comprises a BOPET base film and a functional coating layer coated on the surface of the BOPET base film; the functional coating layer is prepared by coating a composite flame-retardant coating on the surface of the BOPET base film; The BOPET base film comprises a polyester core layer and polyester surface layers which are co-extruded on the upper and lower surfaces of the polyester core layer; The polyester surface layer comprises the following components in parts by weight: The opening master batch is 15 parts; The PET polyester chip is 75 parts; The flame-retardant toughening agent is 10 parts; The polyester core layer comprises the following components in parts by weight: The PET polyester chip is 90 parts; The flame-retardant toughening agent is 10 parts.

[0056] The opening master batch is an FG610 chip from Yizheng, and the PET polyester chip is an FG600 chip from Yizheng; The thickness of the polyester core layer is 100 um, the thickness of the polyester surface layer is 12.5 um*2 layers, and the thickness of the functional coating layer is 100 nm*2 layers.

[0057] The preparation process of the flame-retardant toughening agent is as follows: S101: 1040 parts by weight of terephthalic acid, 550 parts by weight of ethylene glycol, 0.5 parts by weight of antimony trioxide, 0.5 parts by weight of trimethyl phosphate and 200 parts by weight of a functional flame-retardant dispersion liquid are added into a reaction kettle, the temperature of the reaction kettle is raised to 220 DEG C under a nitrogen protective atmosphere, the pressure is raised to 0.5 Mpa, and the reaction kettle is kept at 220 DEG C for 90 min; S102: the temperature in the reaction kettle is raised to 250 DEG C, and the reaction kettle is kept at 250 DEG C for 120 min; S103: the pressure in the reaction kettle is reduced to 250 Pa, and then the temperature in the reaction kettle is raised to 265 DEG C, and the reaction kettle is kept at 265 DEG C for 150 min; S104: small molecular impurities in the reaction system are removed by distillation, and finally a flame-retardant toughening agent with a viscosity of 0.670 dL / g, a melting point of 265 DEG C, an average molecular weight of 32000 and a functional flame-retardant polymer mass percentage of 1.0% is obtained by melt extrusion granulation.

[0058] The preparation process of the functional flame-retardant dispersion liquid is as follows: S201: 12 parts by weight of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide is heated to complete melting under the condition of an oil bath at 140 DEG C. 6 parts by weight of 2,2'-diallyl bisphenol A is added under stirring, and a crude flame-retardant monomer is obtained after the reaction is completed; S202: Dissolve the crude flame retardant monomer in 120 parts by weight of ethanol, 340 parts by weight of deionized water, and stir and wash at a temperature of 90°C for 40 minutes to remove impurities in the crude flame retardant monomer, repeat the washing for 5 times. Dry under vacuum at 180°C, and after the solvent is completely evaporated, obtain the refined flame retardant monomer; S203: Add 100 parts by weight of dichloromethane to a three-necked flask, and add 74 parts by weight of the refined flame retardant monomer and 10 parts by weight of N,N-diethylethylamine, stir until completely dissolved, then slowly add 15 parts by weight of phenyldichlorophosphine. Keep the mixed solution at 45°C for 4 hours under nitrogen atmosphere, after the reaction is completed, extract with petroleum ether and dry thoroughly at 60°C to obtain the functional flame retardant polymer.

[0059] S204: Add 20 parts by weight of the functional flame retardant polymer, 80 parts by weight of ethylene glycol, and 4 parts by weight of polyethylene glycol to a high-speed mixer for uniform dispersion and mixing, the dispersion speed is 800 rpm, and the mixing time is 100 minutes, to obtain the functional flame retardant dispersion liquid; The preparation process of the composite flame retardant coating in this embodiment is as follows: S301: Add 120 parts by weight of polyurethane emulsion (solid content 40%) to a stirred tank, and add 1.0 parts by weight of wetting and leveling agent BYK-333 and 0.2 parts by weight of defoaming agent BYK-024 in sequence under low-speed stirring at 300 rpm, mix for 15 minutes to obtain a resin base solution; S302: Mix 1.0 parts by weight of coupling agent KH-550, 2 parts by weight of dispersant BYK-190, 15 parts by weight of surface flame retardant A, and 15 parts by weight of surface flame retardant B, and disperse at high speed of 3000 rpm for 15-20 minutes to obtain a surface flame retardant slurry; S303: Slowly add the surface flame retardant slurry to the resin base solution, keep medium-speed stirring at 800 rpm for 30 minutes. After stirring, add deionized water to adjust the viscosity to 250 mPas@25°C, and filter to obtain the composite flame retardant coating; The preparation process of the surface flame retardant A is as follows: S401: Add 700 parts by weight of deionized water to 7 parts by weight of montmorillonite, keep medium-speed stirring at 700 rpm for 18 hours. Then add 10 parts by weight of polyvinyl alcohol and continue to stir for 5 hours to obtain a flame retardant premix A; S402: Add 1.5 parts by weight of pentanediol to the flame retardant premix A, and ultrasonic treat for 45 minutes. After drying thoroughly at 60°C, obtain the surface flame retardant A; The preparation process of the surface flame retardant B is as follows: S501: Add 50 parts by weight of dichloromethane, 3.5 parts by weight of adipoyl chloride, and 1.5 parts by weight of triethylamine to a flask, and fully dissolve to obtain a flame retardant premix B; S502: 50 parts by weight of dichloromethane, 3.5 parts by weight of diethyl hydroxymethyl phosphonate were added into a flask, after being dissolved sufficiently, they were slowly added into the flame-retardant premix B at 1°C, after the addition was completed, the reaction was carried out at 30°C for 7h, to obtain the flame-retardant liquid B; S503: the flame-retardant liquid B was extracted with deionized water, after being dried sufficiently at 60°C, the surface flame retardant B was obtained.

[0060] The preparation process of the flame-retardant BOPET film in the embodiment is as follows: S1: the material of the polyester surface layer was transported into the extruder A to carry out melt extrusion according to the formula amount; the material of the polyester core layer was transported into the extruder B to carry out melt extrusion; S2: the melt-extruded polyester surface layer material and the polyester core layer material were melt-extruded through a three-layer co-extrusion die, and an ABA three-layer co-extrusion structure thick sheet was formed by using a rotating cooling roller; S3: the thick sheet was preheated and then bidirectional stretched, the longitudinal stretching was 3.25 times, and the transverse stretching was 3.25 times; S4: after the bidirectional stretched thick sheet was heat-set at 245°C, cooled, pulled, wound and cut, the BOPET base film was obtained; S5: the composite flame-retardant coating was coated on the surface of the BOPET base film by using the pressure of the coating machine roller and the scraping of the coating knife; S6: the coated BOPET base film was sent into a drying box, the coating was dried and solidified by heating and ventilation, the drying temperature was 160°C, and the drying time was 60min; S7: the dried BOPET base film was cooled by a cooling roller, so that the surface temperature was reduced to below room temperature, and the coating was completely solidified, to obtain the flame-retardant BOPET film.

[0061] Example 2 The difference between the embodiment and example 1 is that the addition amount of the surface flame retardant A in step S302 is 10 parts by weight, and the addition amount of the surface flame retardant B is 20 parts by weight.

[0062] Example 3 The difference between the embodiment and example 1 is that the addition amount of the surface flame retardant A in step S302 is 20 parts by weight, and the addition amount of the surface flame retardant B is 10 parts by weight.

[0063] Example 4 The difference between the embodiment and example 1 is that the drying temperature in step S6 is 180°C, and the drying time is 30min.

[0064] Example 5 The difference between the embodiment and example 1 is that no functional coating is set.

[0065] Comparative Example 1 The difference between this comparative example and Example 1 is that the preparation process of the composite flame-retardant coating is as follows: S301: 120 parts by weight of polyurethane emulsion (solid content 40%) was added in a stirred tank, 1.0 parts by weight of wetting and leveling agent BYK-333, 0.2 parts by weight of defoaming agent BYK-024 were added in turn under low-speed stirring at 300 rpm, and mixed for 15 min to obtain a resin base solution; S302: 1.0 parts by weight of coupling agent KH-550, 2 parts by weight of dispersant BYK-190, and 15 parts by weight of surface flame retardant B were mixed and dispersed at 3000 rpm for 15-20 min to obtain a surface flame retardant slurry; S303: The surface flame retardant slurry was slowly added to the resin base solution, and the medium-speed stirring at 800 rpm was maintained for 30 min. After stirring, deionized water was added to adjust the viscosity to 250 mPas@25℃, and filtration was performed to obtain a composite flame-retardant coating.

[0066] Comparative Example 2 The difference between this comparative example and Example 1 is that the preparation process of the composite flame-retardant coating is as follows: S301: 120 parts by weight of polyurethane emulsion (solid content 40%) was added in a stirred tank, 1.0 parts by weight of wetting and leveling agent BYK-333, 0.2 parts by weight of defoaming agent BYK-024 were added in turn under low-speed stirring at 300 rpm, and mixed for 15 min to obtain a resin base solution; S302: 1.0 parts by weight of coupling agent KH-550, 2 parts by weight of dispersant BYK-190, and 15 parts by weight of surface flame retardant A were mixed and dispersed at 3000 rpm for 15-20 min to obtain a surface flame retardant slurry; S303: The surface flame retardant slurry was slowly added to the resin base solution, and the medium-speed stirring at 800 rpm was maintained for 30 min. After stirring, deionized water was added to adjust the viscosity to 250 mPas@25℃, and filtration was performed to obtain a composite flame-retardant coating.

[0067] Comparative Example 3 The difference between this comparative example and Example 1 is that the polyester surface layer includes the following components according to parts by weight: Opening master batch 15 parts; PET polyester chip 75 parts; The polyester core layer includes the following components according to parts by weight: PET polyester chip 90 parts.

[0068] Comparative Example 4 The difference between this comparative example and Example 1 is that the preparation process of the functional flame-retardant dispersion liquid is as follows: S201: 12 parts by weight of binaphthol were heated in an oil bath at 140℃ until completely melted. 6 parts by weight of 2,2'-diallyl bisphenol A were added under stirring, and the crude flame retardant monomer was obtained after the reaction was completed; S202: The crude flame retardant monomer was dissolved in 120 parts by weight of ethanol and 340 parts by weight of deionized water, and washed at 90℃ for 40min to remove impurities in the crude flame retardant monomer, and the washing was repeated 5 times. Drying was carried out at 180℃ under vacuum, and the refined flame retardant monomer was obtained after the solvent was completely evaporated; S203: 100 parts by weight of dichloromethane were added to a three-necked flask, and 74 parts by weight of the above refined flame retardant monomer and 10 parts by weight of N,N-diethyl ethylamine were added. After stirring until completely dissolved, 15 parts by weight of phenyl dichlorophosphine was slowly added. The mixed solution was incubated at 45℃ under nitrogen atmosphere for 4h, and after the reaction was completed, it was extracted with petroleum ether and dried at 60℃ to obtain a functional flame retardant polymer.

[0069] S204: 20 parts by weight of functional flame retardant polymer, 80 parts by weight of ethylene glycol, and 4 parts by weight of polyethylene glycol were added to a high-speed mixer for uniform dispersion and mixing, with a dispersion speed of 800rpm and a mixing time of 100min, to obtain a functional flame retardant dispersion liquid.

[0070] Comparative Example 5 The difference between this comparative example and Example 1 is that the preparation process of the functional flame retardant dispersion liquid is as follows: 20 parts by weight of ammonium polyphosphate APP, 80 parts by weight of ethylene glycol, and 4 parts by weight of polyethylene glycol were added to a high-speed mixer for uniform dispersion and mixing, with a dispersion speed of 800rpm and a mixing time of 100min, to obtain a functional flame retardant dispersion liquid.

[0071] The BOPET films prepared in each example and each comparative example were tested for performance, and the test methods were as follows: Mechanical strength: tested according to GB / T 13542.2-2021; Elongation at break: tested according to GB / T 13542.2-2021; Flame retardant grade: tested according to UL94; LOI index: tested according to GB / T 2406.2.

[0072] The test results are shown in Table 1: Table 1 Mechanical strength / MPa Elongation at break / % Flame retardant rating LOI index / % Example 1 200 150 VTM-0 32.5 Example 2 190 135 VTM-0 33.8 Example 3 210 160 VTM-0 31.4 Example 4 195 140 VTM-0 32.0 Example 5 190 140 VTM-1 27.0 Comparative Example 1 185 130 VTM-1 28.5 Comparative Example 2 185 135 VTM-1 27.8 Comparative Example 3 140 90 VTM-2 26.0 Comparative Example 4 175 120 VTM-2 26.5 Comparative Example 5 150 95 VTM-2 24.5 From the above data, it can be seen that the BOPET prepared by each embodiment of the present application has excellent flame retardant grade, high LOI index, and good mechanical strength and elongation at break, thereby proving that the BOPET film provided by the present application significantly improves the flame retardant performance of the BOPET film while maintaining good mechanical properties, to meet the strict requirements of high-end electronic and electrical, and new energy automobile interior lighting scenes for safety materials.

[0073] The difference between Comparative Example 1 and Example 1 is that no surface flame retardant A is added to the composite flame retardant coating, compared with Example 1, the surface physical flame retardant effect is lacking during the combustion process, resulting in a decrease in flame retardant performance and mechanical properties.

[0074] The difference between Comparative Example 2 and Example 1 is that no surface flame retardant B is added to the composite flame retardant coating, compared with Example 1, the surface chemical flame retardant effect is lacking during the combustion process, resulting in a decrease in flame retardant performance and mechanical properties.

[0075] The difference between Comparative Example 3 and Example 1 is that no flame-retardant toughening agent is added to the BOPET base film, the base film lacks flame retardant effect, and only relying on the coating flame retardant cannot well guarantee the overall flame retardant, in addition, the absence of the toughening agent also leads to a substantial decrease in mechanical properties.

[0076] The difference between Comparative Example 4 and Example 1 is that binaphthol is used instead of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide in step S201, because there is no phosphorus component in the polymer, it cannot capture active free radicals in the combustion chain reaction, and cannot inhibit the gas phase combustion reaction, resulting in a substantial decrease in flame retardant performance and mechanical properties.

[0077] The difference between Comparative Example 5 and Example 1 is that the traditional flame retardant ammonium polyphosphate APP is used instead of the functional flame retardant polymer, because the phosphorus content in the high molecular phosphate salt of the composite phosphorus structure in the present application is higher, and the phosphorus content in the traditional flame retardant is lower, the capture and inhibition effect is not good during the free radical capture process, resulting in a substantial decrease in flame retardant performance and mechanical properties.

[0078] Based on the above ideal embodiments according to the present application, through the above description, relevant personnel can make various changes and modifications without deviating from the technical idea of the present application. The technical scope of the present application is not limited to the contents of the specification, and must be determined by the scope of the claims.

Claims

1. A flame-retardant BOPET film, characterized in that, Including BOPET base film; The raw materials for the BOPET base film include flame retardant toughening agents; The flame retardant toughening agent is prepared using terephthalic acid, ethylene glycol, antimony trioxide, trimethyl phosphate, and functional flame retardant polymers as raw materials. The functional flame-retardant polymer is a phosphate with a complex phosphorus structure.

2. The flame-retardant BOPET film as described in claim 1, characterized in that, The functional flame-retardant polymer is prepared according to the following method: S201: The flame retardant intermediate is heated at 130-150℃ until it melts, and 2,2'-diallylbisphenol A is added under stirring to react and obtain crude flame retardant monomer. S202: The crude flame retardant monomer is dissolved in a solvent, and after stirring and washing at a temperature of 90-100℃, it is dried under vacuum at 180-190℃ to obtain a refined flame retardant monomer. S203: Mix dichloromethane, the refined flame retardant monomer and N,N-diethylethylamine, stir until dissolved, and then add phenyl dichlorophosphine dropwise to obtain a mixed solution; S204: The mixed solution is reacted under an inert gas atmosphere at 40-45°C, then extracted with petroleum ether and dried at 50-60°C to obtain a functional flame-retardant polymer. The flame retardant intermediate is a substance containing biphenyl rings and phenanthrene rings.

3. The flame-retardant BOPET film as described in claim 2, characterized in that, The flame retardant intermediate is 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide.

4. The flame-retardant BOPET film as described in claim 2, characterized in that, The amount of the flame retardant intermediate added in step S201 is 8-16 parts by weight, and the amount of 2,2'-diallyl bisphenol A added is 4-8 parts.

5. The flame-retardant BOPET film as described in claim 2, characterized in that, Based on weight parts, the amount of dichloromethane added in step S203 is 50-100 parts; the amount of refined flame retardant monomer added is 37-74 parts; the amount of N,N-diethylethylamine added is 5-10 parts; and the amount of phenyl dichlorophosphine added is 10-20 parts.

6. The flame-retardant BOPET film as described in claim 1, characterized in that, The flame retardant toughening agent is prepared according to the following method: S101: Using terephthalic acid, ethylene glycol, antimony trioxide, trimethyl phosphate, and functional flame retardant dispersion as raw materials, the first stage of the reaction is carried out under an inert gas protective atmosphere at 200-240℃ and 0.5-0.7 MPa to obtain reaction mixture I; S102: Raise the temperature to 240-260℃ and carry out the second stage of heat preservation reaction to obtain reaction mixture II; S103: Reduce the pressure to 200-300 Pa, then raise the temperature to 260-270 °C to carry out the third stage of heat preservation reaction, and obtain reaction mixture III; S104: Small molecule impurities in reaction mixture III are removed by distillation, and the flame retardant toughening agent is obtained by melt extrusion granulation. The functional flame-retardant dispersion is obtained by mixing and dispersing the functional flame-retardant polymer, ethylene glycol, and dispersant as raw materials.

7. The flame-retardant BOPET film as described in claim 6, characterized in that, Based on weight parts, the amount of terephthalic acid added in step S101 is 1040 parts; the amount of ethylene glycol added is 450-650 parts; the amount of antimony trioxide added is 0.5-1.0 parts; the amount of trimethyl phosphate added is 0.5-1.0 parts; and the amount of functional flame retardant dispersion added is 100-200 parts.

8. The flame-retardant BOPET film as described in claim 6, characterized in that, The amount of the functional flame retardant polymer added to the functional flame retardant dispersion is 10-20 parts by weight; the amount of ethylene glycol added is 80-90 parts; and the amount of dispersant added is 3-5 parts.

9. The flame-retardant BOPET film according to any one of claims 1-8, characterized in that, The flame-retardant BOPET film also includes a functionalized coating applied to the surface of the BOPET base film; The functionalized coating is prepared by applying a composite flame-retardant coating to the surface of the BOPET base film; The composite flame-retardant coating is prepared using resin-based liquid, surface flame retardant A, and surface flame retardant B as raw materials. The surface flame retardant A is prepared according to the following method: S401: Add deionized water to montmorillonite, stir, then add polyvinyl alcohol and continue stirring to obtain flame retardant premix A; S402: Add pentanediol to the flame retardant premix A, sonicate, and dry at 60-80°C to obtain surface flame retardant A; The surface flame retardant B is prepared according to the following method: S501: Dichloromethane, acyl halide compounds, and triethylamine are mixed to obtain flame retardant premix B; S502: Dichloromethane and phosphonate compounds are mixed and then added dropwise to the flame retardant premix B at 0-5°C. After the addition is complete, the mixture is reacted at 30-35°C to obtain flame retardant liquid B. S503: Extract the flame retardant liquid B with deionized water, and dry it at 60-80℃ to obtain surface flame retardant B.

10. The flame-retardant BOPET film as described in claim 9, characterized in that, The acyl halide compound is adipic acid chloride; the phosphonate compound is diethyl hydroxymethylphosphonate.

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