Flame-retardant polyvinyl fluoride film and application thereof

Abstract

The invention discloses a flame-retardant polyvinyl fluoride film which comprises the following components in parts by mass: 100 parts of PVF resin, 5-20 parts of a methacrylate polymer, 5-20 parts of ammonium polyphosphate and 0.1-5 parts of melamine, the mass ratio of the methacrylate polymer to the ammonium polyphosphate is 0.2: 1-2: 1, the 12s vertical burning length of the flame-retardant polyvinyl fluoride film is less than or equal to 200mm, and the smoke density DS is less than 100. The flame-retardant polyvinyl fluoride film disclosed by the invention is short in vertical burning distance and extremely small in smoke release amount, the high flame-retardant property of the polyvinyl fluoride film is improved, and the application field of the polyvinyl fluoride flame-retardant film is expanded.

Description

Technical Field

[0001] The present invention relates to the technical field of polyvinyl fluoride films, and particularly relates to a flame-retardant polyvinyl fluoride film and its application. Background Art

[0002] Sound insulation / heat insulation insulating materials are installed in all pressurized parts of the aircraft cabin, from the nose to the tail. These sound insulation and heat insulation insulating materials are the composites with the largest consumption on the aircraft. In addition to requirements such as weight, volume, sound insulation, heat insulation, vibration damping, and corrosion prevention, they also require properties such as flame propagation resistance, high and low temperature resistance, and water vapor barrier. Therefore, insulating bags or coating layers are required to provide functional protection for the sound insulation / heat insulation materials used in aircraft. The insulating bag or coating layer is a film composite structure composed of a polymer film, a barrier layer, an adhesive, and a support layer, mainly playing the roles of outer protection, flame retardancy, high and low temperature resistance, and reducing water vapor permeation.

[0003] Polyvinyl fluoride (PVF) film is manufactured by special processing of PVF resin, and has excellent aging resistance, thermal stability, chemical and solvent resistance, flame retardancy and low smoke characteristics, abrasion resistance, self-cleaning property, mechanical properties, etc. These characteristics make PVF film a standard equipment for the protection of aircraft interior and structural materials. Over the years, the changing standards have become increasingly strict. The aviation authority's requirements for the flame retardancy standard of insulating bags or coating layers have been continuously improved, gradually developing towards high flame retardancy, low smoke, low heat release, and easy cleaning. PVF films that meet the requirements of insulating bags need to add flame retardants to improve their flame retardancy.

[0004] US3963672A patent discloses a flame-retardant polyvinyl fluoride film, which contains about 3-30 wt% of sodium antimonate, potassium antimonate, zinc antimonate, magnesium antimonate, or aluminum antimonate as the only flame retardant additive. When the test sample is at 25°, 35°, or 50° with the horizontal plane, the burning distance of the test sample during the 12 s horizontal burning is zero. The particle size of sodium antimonate in this patent is 200 mesh (74 μm), which can only be used as a functional filler for relatively thick films. In addition, as an inorganic filler, the density of sodium antimonate is 3.7 g / cm 3 , and the surface density of the film will be significantly increased after addition. Summary of the Invention

[0005] In view of the above technical problems, the present invention proposes a solution to improve the flame retardancy of polyvinyl fluoride film by adding methacrylate polymer and intumescent flame retardant. At the same time, the polyvinyl fluoride film has a low surface density and is lightweight.

[0006] The technical solution of the present invention is as follows:

[0007] In the first aspect of the present invention, the present invention provides a flame-retardant polyvinyl fluoride film, and the flame-retardant polyvinyl fluoride film comprises the following components in parts by mass:

[0008] 100 parts of PVF resin;

[0009] 5 - 20 parts of methacrylate polymer;

[0010] 5 - 20 parts of ammonium polyphosphate;

[0011] 0.1 - 5 parts of melamine,

[0012] The mass ratio of the methacrylate polymer to ammonium polyphosphate is 0.2:1 - 2:1,

[0013] The vertical burning length of the flame - retardant polyvinyl fluoride film within 12 s is ≤200 mm, and the smoke density D S <100.

[0014] Furthermore, the flame - retardant polyvinyl fluoride film comprises the following components by mass parts:

[0015] 100 parts of PVF resin,

[0016] 5 - 15 parts of methacrylate polymer,

[0017] 5 - 15 parts of ammonium polyphosphate,

[0018] 0.5 - 5 parts of melamine.

[0019] Furthermore, the vertical burning length of the flame - retardant polyvinyl fluoride film within 12 s is ≤150 mm, and the smoke density D S <90.

[0020] The surface density of the flame - retardant polyvinyl fluoride film of the present invention is 10 - 30 g / m 2 , preferably, the surface density is 10 - 20 g / m 2 .

[0021] The purpose of adding the methacrylate polymer component is to promote system compatibility. Ammonium polyphosphate and melamine are both insoluble in latent solvents, and the system compatibility is poor, resulting in precipitation during the extrusion and stretching process. Adding the methacrylate polymer to the formulation effectively improves the system compatibility, and the precipitation of components is significantly weakened or no longer occurs.

[0022] In the flame - retardant formulation, the methacrylate polymer decomposes and releases CH 3 OH, CO 2 and H 2 O when heated, and ammonium polyphosphate releases NH 3, generating acidic substances, which react with the alcohol compounds produced by the methacrylate polymer to undergo esterification. During the esterification process, the esterification products are dehydrated into carbon, further inhibiting the melting and dripping of the polymer. These carbons expand and foam and cover the surface of the substrate, forming a honeycomb-shaped insulating carbon layer, which cuts off contact with oxygen and the escape of combustibles, thereby effectively preventing the material from continuing to burn. At the same time, melamine absorbs heat and releases non-combustible gas NH 3 The non-combustible gas takes away the heat and combustibles, lowering the surface temperature of the polymer, thereby changing the thermal oxidation degradation process and causing it to carbonize rapidly to form non-combustible carbon.

[0023] The test results of the present invention show that the flame-retardant polyvinyl fluoride film must contain methacrylate polymer, ammonium polyphosphate and melamine components at the same time, and the presence of any two components alone cannot achieve a flame-retardant effect.

[0024] The mass ratio of the methacrylate polymer to the ammonium polyphosphate of the present invention is 0.2:1 to 2:1, and further, the mass ratio is 0.2:1 to 1:1. When the mass ratio of the methacrylate polymer to the ammonium polyphosphate is greater than 2, the combustion is violent and the flame retardant effect is poor. When the mass ratio of the methacrylate polymer to the ammonium polyphosphate is less than 0.2, the flame retardant effect is poor.

[0025] The mass ratio of ammonium polyphosphate to melamine in the present invention is 2:1 to 20:1. The increase in the amount of melamine will increase the amount of NH 3 The amount of release takes away heat and combustibles, reduces the surface temperature of the polymer, and thus changes the thermal oxidation degradation process to make it rapidly carbonized to form incombustible carbon. Furthermore, the mass ratio is 5:1 to 9:1. Ammonium polyphosphate and melamine can be added at the same time, or in the form of melamine microencapsulated ammonium polyphosphate, but the particle size of melamine microencapsulated ammonium polyphosphate is relatively large, with an average particle size of more than 20 μm, which will affect the processing continuity and mechanical properties of the lightweight film; preferably, ammonium polyphosphate and melamine are added separately.

[0026] The PVF resin of the present invention can be a homopolymer of vinyl fluoride (VF), or a copolymer of vinyl fluoride and other monomers co-polymerizable with vinyl fluoride. When the PVF resin is a copolymer, the weight proportion of the vinyl fluoride structural unit in the PVF resin is ≥75%.

[0027] The monomer copolymerizable with vinyl fluoride is selected from at least one of butyl methacrylate, methacrylic acid, butyl acrylate, ethyl acrylate, acrylic acid and methacrylic acid.

[0028] The methacrylate polymer in the present invention is a methacrylate homopolymer or a copolymer of methacrylate and one or more selected from butyl methacrylate, methacrylic acid, butyl acrylate, ethyl acrylate, acrylic acid, and methacrylic acid, wherein the molar content of the methacrylate structural unit is 50% to 90%. Preferably, it is a methacrylate homopolymer, namely PMMA.

[0029] The ammonium polyphosphate in the present invention is selected from ammonium polyphosphate or ammonium polyphosphate with a microcapsule structure.

[0030] The melamine in the present invention is selected from at least one of melamine cyanurate, melamine formaldehyde resin, and other derivatives.

[0031] The flame-retardant polyvinyl fluoride film in the present invention has high bond strength after aluminizing and is not easily delaminated, and can be compounded with other materials.

[0032] In the second aspect of the present invention, the present invention also provides a method for preparing a flame-retardant polyvinyl fluoride film. The preparation method includes the following steps: PVF resin, methacrylate polymer, ammonium polyphosphate, melamine, and latent solvent are mixed, and then subjected to biaxial stretching after extrusion or casting after extrusion and heat setting at a high temperature to obtain the flame-retardant polyvinyl fluoride film.

[0033] The latent solvent is selected from at least one of N,N-dimethylformamide, N,N-dimethylacetamide, propylene carbonate, dimethyl phthalate, isophorone, and γ-butyrolactone. By weight, the mass ratio of the latent solvent to the PVF resin is 1:1 to 3:1.

[0034] The extrusion temperature is 130°C to 180°C, and the extrusion machine speed is 10 to 300 rpm.

[0035] Longitudinal stretching process: The preheating temperature is 60 to 120°C, the stretching temperature is 90 to 130°C, and the longitudinal stretching ratio is 1.5 to 3.5.

[0036] Transverse stretching process: The preheating temperature is 80 to 155°C, the stretching temperature is 100 to 130°C, and the transverse stretching ratio is 1.5 to 4.0.

[0037] Heat setting process: The heat setting temperature is 160 to 220°C.

[0038] Casting process: The temperature of the casting roll is 35 to 70°C, and the linear speed of the casting roll is 1.0 to 10.0 m / min.

[0039] In the third aspect of the present invention, the present invention also provides an application of the flame-retardant polyvinyl fluoride film. The flame-retardant polyvinyl fluoride film is used as an outer protective film for aircraft products, such as aircraft insulation bags and aircraft coatings.

[0040] The technical solution of the present invention has the following technical effects compared with the prior art:

[0041] The flame-retardant polyvinyl fluoride film of the present invention contains a methacrylate polymer, ammonium polyphosphate and melamine, and the combined action of the three improves the flame retardancy of the film, making the vertical burning length of the polyvinyl fluoride film ≤ 200 mm in 12 s, and the smoke density D S <100, and the areal density is 10 - 30 g / m 2 . Specific embodiments

[0042] The present invention will be further described below in conjunction with specific embodiments, but the present invention is not limited to these specific embodiments. Those skilled in the art should recognize that the present invention covers all alternative, improved and equivalent solutions that may be included within the scope of the claims.

[0043] The test methods for the examples and comparative examples of the present invention are as follows:

[0044] The 12 s vertical burning length is measured in accordance with Part I b(4) of Appendix F of CCAR-25-R4.

[0045] The smoke density is measured in accordance with MHT6040-2017 "Test Method for Smoke Density of Aeronautical Materials".

[0046] The areal density is measured in accordance with Part 2 of HB 7736.2-2004 "Test Methods for Physical Properties of Composite Material Prepregs".

[0047] The film thickness is measured in accordance with GB / 6672-2001.

[0048] Example 1

[0049] 100 parts of PVF resin, 10 parts of PMMA, 15 parts of ammonium polyphosphate (APP) and 3 parts of melamine cyanurate (MCA) are added to 180 parts of N,N-dimethylacetamide (DMAc) and stirred at high speed for about 30 minutes; the prepared PVF resin slurry is extruded into a cast sheet through a twin-screw extruder, a filter, a melt metering pump and a die, and the cast sheet is cooled and shaped at 40 °C by a cold roll. The cast sheet passes through a stretching roller for longitudinal stretching, with a longitudinal stretching ratio of 2 times, a preheating temperature of 70 °C and a stretching temperature of 100 °C; it is then further stretched transversely and degassed and heat-set on a transverse stretching machine, with a transverse stretching ratio of 2.5 times, a preheating temperature of 110 °C and a stretching temperature of 130 °C; the degassing and heat-setting mainly removes the residual latent solvent on the film, eliminates the internal stress of the film and improves the thermal dimensional stability of the film, with the temperature controlled at 190 °C; the PVF film is further subjected to corona treatment, with a surface treatment voltage of 380 V and a frequency of 18 kHz, to obtain a biaxially stretched PVF film.

[0050] Example 2

[0051] Same as Example 1, except that the formulation of the PVF film is 100 parts of PVF resin, 15 parts of PMMA, and 15 parts of melamine microencapsulated ammonium polyphosphate.

[0052] Example 3

[0053] Same as Example 1, except that the formulation of the PVF film is 100 parts of PVF resin, 7.5 parts of PMMA, 10 parts of APP, and 1.5 parts of MCA.

[0054] Example 4

[0055] Same as Example 1, except that the formulation of the PVF film is 100 parts of PVF resin, 5 parts of PMMA, 20 parts of APP, and 3 parts of MCA.

[0056] Example 5

[0057] 100 parts of PVF resin, 10 parts of PMMA, 15 parts of APP, and 3 parts of MCA were added to 180 parts of DMAc and stirred at high speed for dispersion for about 30 minutes; the prepared PVF resin slurry was extruded into a sheet through a twin-screw extruder, a filter, a melt metering pump, and a die, and the sheet was cooled and shaped by a cold roll at 40 °C. The line speed of the casting roll was 5 m / min, the shaping temperature was 180 °C, and the shaping time was 90 s to obtain an extruded cast flame-retardant PVF film.

[0058] Comparative Example 1

[0059] Same as Example 1, except that the formulation of the PVF film is 100 parts of PVF resin, 15 parts of APP, and PMMA and MCA are not added.

[0060] Comparative Example 2

[0061] Same as Example 1, except that the formulation of the PVF film is 100 parts of PVF resin, 15 parts of APP, 3 parts of MCA, and PMMA is not added.

[0062] Comparative Example 3

[0063] Same as Example 1, except that the formulation of the PVF film is 100 parts of PVF resin, 10 parts of PMMA, and APP and MCA are not added.

[0064] Comparative Example 4

[0065] Same as Example 1, except that the formulation of the PVF film is 100 parts of PVF resin, 15 parts of PMMA, 5 parts of APP, 1 part of MCA, and the weight ratio of PMMA to APP is 3:1.

[0066] The formulation tables of the comparative examples and examples of this application are shown in Table 1.

[0067] Table 1 Formulation tables of the comparative examples and examples in this application

[0068]

[0069] The thickness, surface density, smoke density, and 12s vertical burning performance of the PVF films prepared in Examples 1-5 and Comparative Examples 1-4 were tested. The test results are shown in Table 2.

[0070] Table 2 Test results of PVF film properties

[0071]

[0072]

[0073] It can be seen from the data in Table 2 that: in the PVF film of Comparative Example 1, only ammonium polyphosphate was added. During the 12s vertical burning test, the film was burned through, the damage length was high, and it continued to burn after the flame was removed. The amount of smoke released was large. It not only did not play a flame retardant effect but also burned more violently. In the PVF film of Comparative Example 2, ammonium polyphosphate and melamine were added. During the 12s vertical burning test, the film was still burned through and continued to burn after the flame was removed. The amount of smoke released was less than that when only ammonium polyphosphate was added. Adding only ammonium polyphosphate or adding ammonium polyphosphate and melamine simultaneously in the PVF film could not play a flame retardant effect and burned more violently. In the PVF film of Comparative Example 3, only PMMA was added. During the 12s vertical burning test, the damage length was limited but it continued to burn after the flame was removed, and the amount of smoke released was large. Although the PVF film of Comparative Example 4 added PMMA, ammonium polyphosphate, and melamine simultaneously, the dosage ratio of PMMA to ammonium polyphosphate was greater than 2:1, and the flame retardant effect was poor.

Claims

1. A flame-retardant polyvinyl fluoride film, characterized in that: The flame-retardant polyvinyl fluoride film comprises the following components by mass parts: 100 parts of PVF resin; 5 - 20 parts of methacrylate polymer; 5 - 20 parts of ammonium polyphosphate; 0.1 - 5 parts of melamine, The mass ratio of the methacrylate polymer to ammonium polyphosphate is 0.2:1 - 2:1, The vertical burning length of the flame-retardant polyvinyl fluoride film is ≤ 200 mm, and the smoke density D S < 100.

2. The flame-retardant polyvinyl fluoride film according to claim 1, characterized in that: The flame-retardant polyvinyl fluoride film comprises the following components by mass parts: 100 parts of PVF resin; 5 - 15 parts of methacrylate polymer; 5 - 15 parts of ammonium polyphosphate; 0.5 - 5 parts of melamine, The mass ratio of the methacrylate polymer to ammonium polyphosphate is 0.2:1 - 1:

1.

3. The flame-retardant polyvinyl fluoride film according to claim 1 or 2, characterized in that: The vertical burning length of the flame-retardant polyvinyl fluoride film is ≤ 150 mm for 12 s, and the smoke density D S <90.

4. The flame-retardant polyvinyl fluoride film according to claim 1, characterized in that: The mass ratio of ammonium polyphosphate to melamine is 2:1 - 20:

1.

5. The flame-retardant polyvinyl fluoride film according to claim 4, characterized in that: The mass ratio of ammonium polyphosphate to melamine is 5:1 - 9:

1.

6. The flame-retardant polyvinyl fluoride film according to claim 1, characterized in that: The methacrylate polymer is PMMA.

7. The flame-retardant polyvinyl fluoride film according to claim 1, characterized in that: The surface density of the flame-retardant polyvinyl fluoride film is 10-30 g / m 2 .

8. The flame-retardant polyvinyl fluoride film according to claim 1, characterized in that: The melamine is selected from at least one of melamine cyanurate, melamine formaldehyde resin and other derivatives.

9. The flame-retardant polyvinyl fluoride film according to claim 1, characterized in that: The PVF resin is a homopolymer or copolymer of VF.

10. An application of the flame-retardant polyvinyl fluoride film according to any one of claims 1 - 9, characterized in that: The flame-retardant polyvinyl fluoride film is used as an outer protective film for aircraft insulation bags and aircraft coatings.

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