Flame-retardant film containing flame-retardant EVA and preparation method of flame-retardant film

Abstract

The invention relates to the technical field of EVA, and discloses a flame-retardant film containing flame-retardant EVA and a preparation method of the flame-retardant film. The flame-retardant film is composed of a flame-retardant PET polyester layer, a polyurethane layer and a flame-retardant EVA layer; 2, 4, 6-tris [4-(mercaptoacetamide) phenyl]-1, 3, 5-triazine and divinyl adipate are subjected to a mercapto-ene click reaction, a polymer capsule wall is generated through crosslinking on the surface of ammonium polyphosphate, an ammonium polyphosphate microcapsule is obtained, then the ammonium polyphosphate microcapsule and EVA resin are subjected to melt blending, and flame-retardant EVA is obtained. And a cross-linked polymer of the capsule wall of the ammonium polyphosphate microcapsule contains a triazine ring and a plurality of benzene ring structures with high carbon content, and forms an intumescent flame-retardant system with ammonium polyphosphate, so that the flame-retardant property of EVA (Ethylene-Vinyl Acetate) is improved. The compatibility of the ammonium polyphosphate microcapsule and the EVA is good, the influence of the microcapsule on the mechanical property of the EVA is reduced, and the EVA keeps good mechanical strength.

Description

Technical Field

[0001] The invention relates to the technical field of EVA, in particular to a flame retardant film containing flame retardant EVA and a preparation method thereof. Background Art

[0002] EVA (ethylene-vinyl acetate copolymer) exhibits excellent toughness, impact resistance, and low-temperature resistance. Compounding EVA with polyethylene terephthalate, polyurethane, polyethylene, and other materials can create high-performance multi-layer composite films, widely used in packaging, plastic sealing, the automotive industry, and agriculture. However, conventional EVA easily burns when exposed to open flames, posing a significant safety hazard.

[0003] Adding flame retardants such as ammonium polyphosphate to EVA materials can improve the flame retardancy of EVA and its composite film materials. However, ammonium polyphosphate is highly hygroscopic, has poor hydrolysis resistance, and is prone to agglomeration, which can affect the material's flame retardancy and other properties. Hydrophobic microcapsules, such as melamine resin microcapsules, epoxy resin microcapsules, and unsaturated polyester resin microcapsules, can improve their hydrolysis resistance and other properties. However, the capsule walls of these microcapsules are not compatible with EVA, significantly affecting the material's mechanical properties. Summary of the Invention

[0004] The purpose of the present invention is to provide a flame retardant film containing flame retardant EVA, which solves the problem that EVA and its composite film materials have poor flame retardant properties.

[0005] To achieve the above-mentioned purpose, the technical solution adopted by the present invention is a flame-retardant film containing flame-retardant EVA and a preparation method thereof; the flame-retardant film is composed of a flame-retardant PET polyester layer, a polyurethane layer, and a flame-retardant EVA layer; the preparation method of the flame-retardant film comprises: biaxially stretching flame-retardant polyethylene terephthalate to form a flame-retardant PET polyester layer, and corona treating it with a corona machine; then spraying polyurethane on one side of the flame-retardant PET polyester layer, and baking and curing it to form a polyurethane layer; then melting the flame-retardant EVA, casting it through a casting machine and coating it on the polyurethane layer, and finally cooling, pulling, and winding it through an extruder roller to obtain a flame-retardant film containing flame-retardant EVA.

[0006] The preparation method of flame retardant EVA is: (1) Add ammonium polyphosphate to ethanol and disperse it by ultrasonication. Then add N,N-dimethylformamide as a cosolvent, 2,4,6-tris[4-(mercaptoacetamide)phenyl]-1,3,5-triazine, divinyl adipate, and an alkali catalyst. Stir and react in a nitrogen atmosphere. Remove the solvent by vacuum distillation. Wash with ethanol and water, and dry to obtain ammonium polyphosphate microcapsules.

[0007] (2) Ethylene-vinyl acetate copolymer and ammonium polyphosphate microcapsules are mixed, then blended and extruded in a twin-screw extruder, and pelletized to obtain flame-retardant EVA.

[0008] Preferably, (1) the reaction temperature is 15-25°C, and the reaction time is 2-3 hours.

[0009] Preferably, the mass ratio of ammonium polyphosphate, 2,4,6-tris[4-(mercaptoacetamide)phenyl]-1,3,5-triazine, divinyl adipate, and base catalyst in (1) is 100:(6-10):(3.1-5.2):(0.1-0.16).

[0010] Preferably, the base catalyst comprises triethylamine.

[0011] Preferably, the mass ratio of ethylene-vinyl acetate copolymer to ammonium polyphosphate microcapsules in (2) is 100:(30-70).

[0012] Preferably, the temperature of zones 1-6 of the twin-screw extruder in (2) is 140-175°C, and the screw speed is 100-200 r / min.

[0013] Preferably, the preparation method of 2,4,6-tris[4-(mercaptoacetamide)phenyl]-1,3,5-triazine is as follows: 2,4,6-tris(4-aminophenyl)-1,3,5-triazine, thioglycolic acid, N,N-diisopropylethylamine, and 2-(7-azabenzotriazole)-N,N,N',N'-tetramethyluronium hexafluorophosphate (HATU) are added to N,N-dimethylformamide. After the reaction, the solvent is removed by distillation under reduced pressure, the mixture is washed with water, and the product is recrystallized from dichloromethane to obtain 2,4,6-tris[4-(mercaptoacetamide)phenyl]-1,3,5-triazine. The reaction formula is: .

[0014] Preferably, the molar ratio of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine, thioglycolic acid, N,N-diisopropylethylamine, and 2-(7-azabenzotriazole)-N,N,N',N'-tetramethyluronium hexafluorophosphate is 1:(3-3.6):(6-6.9):(6-6.9).

[0015] (III) Beneficial technical effects: The present invention uses triethylamine as a catalyst to carry out a thiol-ene click reaction on 2,4,6-tris[4-(mercaptoacetamide)phenyl]-1,3,5-triazine containing three thiol groups and divinyl adipate containing two olefinic groups, and cross-links the polymer capsule wall on the surface of ammonium polyphosphate to obtain ammonium polyphosphate microcapsules, which are then melt-blended with EVA resin to obtain flame-retardant EVA. The cross-linked polymer of the ammonium polyphosphate microcapsule wall contains ethyl acetate structural units similar to those of EVA ( ), which makes the ammonium polyphosphate microcapsules have good compatibility with EVA, reduces the impact of microcapsules on the mechanical properties of EVA, and enables EVA to maintain good tensile strength and impact strength.

[0016] The cross-linked polymer of the ammonium polyphosphate microcapsule wall contains triazine rings and multiple benzene ring structures with high carbon content, which form an intumescent flame retardant system with the ammonium polyphosphate. The system burns to form an intumescent carbon layer on the EVA surface, significantly reducing the heat release rate and total heat release during EVA combustion and improving the flame retardant performance.

[0017] The present invention further forms a multi-layer composite film with flame-retardant polyethylene terephthalate, a polyurethane adhesive layer and flame-retardant EVA, and utilizes the flame-retardant EVA layer to improve the overall flame-retardant performance of the composite film. DETAILED DESCRIPTION

[0018] The present invention will be described in detail below with reference to specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention.

[0019] Ethylene-vinyl acetate copolymer, brand DuPont 210W, purchased from Guangzhou Hongcheng Plastics Co., Ltd. Flame retardant

[0020] Example 1 (1) To 200 mL of N,N-dimethylformamide, 50 mmol of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine, 180 mmol of thioglycolic acid, 330 mmol of N,N-diisopropylethylamine, and 330 mmol of 2-(7-azabenzotriazole)-N,N,N',N'-tetramethyluronium hexafluorophosphate were added. The mixture was reacted at 25°C for 12 h. The solvent was removed by distillation under reduced pressure, and the mixture was washed with water. The product was recrystallized from dichloromethane to obtain 2,4,6-tris[4-(mercaptoacetamide)phenyl]-1,3,5-triazine.

[0021] (2) Add 300 g of ammonium polyphosphate to 1 L of ethanol and disperse it by ultrasonication. Then add 200 mL of N,N-dimethylformamide as a cosolvent, 18 g (about 31.25 mmol) of 2,4,6-tris[4-(mercaptoacetamide)phenyl]-1,3,5-triazine, 9.3 g (about 47 mmol) of divinyl adipate, and 0.3 g of triethylamine. Stir and react in a nitrogen atmosphere. Remove the solvent by distillation under reduced pressure. Wash with ethanol and water, and dry to obtain ammonium polyphosphate microcapsules.

[0022] (3) 1 kg of ethylene-vinyl acetate copolymer and 0.3 kg of ammonium polyphosphate microcapsules were mixed and then extruded in a twin-screw extruder. The temperatures in zones 1-6 were 140°C, 160°C, 170°C, 175°C, 175°C, and 170°C, and the screw speed was 100 r / min. The mixture was pelletized to obtain flame-retardant EVA.

[0023] Comparative Example 1 (1) 1 kg of ethylene-vinyl acetate copolymer and 0.3 kg of ammonium polyphosphate were mixed and then extruded in a twin-screw extruder. The temperatures in zones 1-6 were 140°C, 160°C, 170°C, 175°C, 175°C, and 170°C, and the screw speed was 100 r / min. The mixture was pelletized to obtain flame-retardant EVA.

[0024] Comparative Example 2 (1) 300 g of ammonium polyphosphate was added to 1 L of ethanol and dispersed by ultrasonication. 200 mL of N,N-dimethylformamide as a cosolvent, 11.13 g (31.25 mmol) of trimethylolpropane tris(thioglycolic acid) (CAS No. 10193-96-1), 9.3 g of divinyl adipate, and 0.3 g of triethylamine were added and stirred in a nitrogen atmosphere for reaction. The solvent was removed by distillation under reduced pressure, and the mixture was washed with ethanol and water and dried to obtain ammonium polyphosphate microcapsules.

[0025] (2) 1 kg of ethylene-vinyl acetate copolymer and 0.3 kg of ammonium polyphosphate microcapsules were mixed and then extruded in a twin-screw extruder. The temperatures in zones 1-6 were 140°C, 160°C, 170°C, 175°C, 175°C, and 170°C, and the screw speed was 100 r / min. The mixture was pelletized to obtain flame-retardant EVA.

[0026] Comparative Example 3 (1) 300 g of ammonium polyphosphate was added to 1 L of ethanol and dispersed by ultrasonication. 200 mL of N,N-dimethylformamide as a cosolvent, 18 g of 2,4,6-tris[4-(mercaptoacetamide)phenyl]-1,3,5-triazine (prepared in the same manner as in Example 1), 7.24 g (47 mmol) of N,N-methylenebisacrylamide (CAS No. 110-26-9), and 0.3 g of triethylamine were added and stirred in a nitrogen atmosphere for reaction. The solvent was removed by distillation under reduced pressure, and the mixture was washed with ethanol and water and dried to obtain ammonium polyphosphate microcapsules.

[0027] (2) 1 kg of ethylene-vinyl acetate copolymer and 0.3 kg of ammonium polyphosphate microcapsules were mixed and then extruded in a twin-screw extruder. The temperatures in zones 1-6 were 140°C, 160°C, 170°C, 175°C, 175°C, and 170°C, and the screw speed was 100 r / min. The mixture was pelletized to obtain flame-retardant EVA.

[0028] Example 2 (1) To 200 mL of N,N-dimethylformamide, 50 mmol of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine, 150 mmol of thioglycolic acid, 300 mmol of N,N-diisopropylethylamine, and 300 mmol of 2-(7-azabenzotriazole)-N,N,N',N'-tetramethyluronium hexafluorophosphate were added. The mixture was reacted at 30°C for 12 h. The solvent was removed by distillation under reduced pressure, and the mixture was washed with water. The product was recrystallized from dichloromethane to obtain 2,4,6-tris[4-(mercaptoacetamide)phenyl]-1,3,5-triazine.

[0029] (2) Add 300 g of ammonium polyphosphate to 1.2 L of ethanol and disperse it by ultrasonication. Then add 250 mL of N,N-dimethylformamide as a cosolvent, 30 g of 2,4,6-tris[4-(mercaptoacetamide)phenyl]-1,3,5-triazine, 15.6 g of divinyl adipate, and 0.48 g of triethylamine. Stir and react in a nitrogen atmosphere. Remove the solvent by distillation under reduced pressure. Wash with ethanol and water, and dry to obtain ammonium polyphosphate microcapsules.

[0030] (3) 1 kg of ethylene-vinyl acetate copolymer and 0.5 kg of ammonium polyphosphate microcapsules were mixed and then extruded in a twin-screw extruder. The temperatures in zones 1-6 were 140°C, 160°C, 170°C, 175°C, 175°C, and 170°C, and the screw speed was 200 r / min. The mixture was pelletized to obtain flame-retardant EVA.

[0031] Example 3 (1) To 300 mL of N,N-dimethylformamide, 50 mmol of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine, 165 mmol of thioglycolic acid, 345 mmol of N,N-diisopropylethylamine, and 345 mmol of 2-(7-azabenzotriazole)-N,N,N',N'-tetramethyluronium hexafluorophosphate were added. The mixture was reacted at 15°C for 18 h. The solvent was removed by distillation under reduced pressure, and the mixture was washed with water. The product was recrystallized from dichloromethane to obtain 2,4,6-tris[4-(mercaptoacetamide)phenyl]-1,3,5-triazine.

[0032] (2) Add 300 g of ammonium polyphosphate to 1.2 L of ethanol and disperse it by ultrasonication. Then add 200 mL of N,N-dimethylformamide as a cosolvent, 23.7 g of 2,4,6-tris[4-(mercaptoacetamide)phenyl]-1,3,5-triazine, 12.4 g of divinyl adipate, and 0.4 g of triethylamine. Stir and react in a nitrogen atmosphere. Remove the solvent by distillation under reduced pressure. Wash with ethanol and water, and dry to obtain ammonium polyphosphate microcapsules.

[0033] (3) 1 kg of ethylene-vinyl acetate copolymer and 0.7 kg of ammonium polyphosphate microcapsules were mixed and then extruded in a twin-screw extruder. The temperatures in zones 1-6 were 140°C, 160°C, 170°C, 175°C, 175°C, and 170°C, and the screw speed was 200 r / min. The mixture was pelletized to obtain flame-retardant EVA.

[0034] Flame-retardant EVA was compression molded using a flat-bed vulcanizer at 140°C and 10 MPa. Tensile properties were tested according to GB / T 1040.1-2018. Impact strength was tested according to GB / T 1843-2008.

[0035] Table 1 Mechanical properties of flame retardant EVA Tensile strength (MPa) <![CDATA[Impact strength (kJ / m 2 )]]> Example 1 9.4 25.8 Comparative Example 1 7.8 22.6 Comparative Example 2 9.1 26.3 Comparative Example 3 8.3 23.9 Example 2 8.5 23.0 Example 3 6.9 18.7 After testing, in Comparative Example 1, ammonium polyphosphate was added to EVA, and the compatibility between the two was poor, which affected the mechanical properties of EVA and resulted in low tensile strength and impact strength of EVA. In Example 1, a cross-linked polymer of 2,4,6-tris[4-(mercaptoacetamide)phenyl]-1,3,5-triazine and divinyl adipate was used as the capsule wall of ammonium polyphosphate to prepare ammonium polyphosphate microcapsules. The cross-linked polymer of the capsule wall contained ethyl acetate structural units similar to those of EVA ( ), which makes the ammonium polyphosphate microcapsules have good compatibility with EVA, reduces the impact of microcapsules on the mechanical properties of EVA, and enables EVA to maintain good tensile strength and impact strength.

[0036] Comparative Example 2 uses a cross-linked polymer of trimethylolpropane tris(thioglycolic acid) and divinyl adipate as the capsule wall of ammonium polyphosphate microcapsules, which contains ethyl acetate structural units, has good compatibility with EVA, has little effect on the mechanical properties of EVA, and can maintain high tensile strength and impact strength.

[0037] Comparative Example 3 uses a cross-linked polymer of 2,4,6-tris[4-(mercaptoacetamide)phenyl]-1,3,5-triazine and N,N-methylenebisacrylamide as the capsule wall of ammonium polyphosphate microcapsules, which does not contain ethyl acetate structural units and has poor compatibility with EVA, resulting in low tensile strength and impact strength of EVA.

[0038] The combustion performance of EVA was tested by cone calorimeter with a thermal radiation power of 35kW / m 2 The sample size is 10 cm × 10 cm × 0.4 cm. The blank sample is EVA without ammonium polyphosphate.

[0039] Table 2 Flame retardant properties of EVA Peak heat release rate (W / g) Total heat release (kJ / g) Example 1 387.4 19.4 Comparative Example 1 465.2 21.6 Comparative Example 2 471.7 21.9 Comparative Example 3 389.3 19.5 Blank sample 842.6 38.1 Example 2 336.7 16.8 Example 3 285.0 15.3 The EVA blank sample without ammonium polyphosphate exhibited high peak heat release rate and total heat release, resulting in poor flame retardancy. Comparative Example 1, in which ammonium polyphosphate was added, exhibited significantly lower peak heat release rate and total heat release. Examples 1-3 incorporated ammonium polyphosphate microcapsules. The cross-linked polymer in the capsule wall contained triazine rings and multiple high-carbon benzene ring structures, which formed an intumescent flame retardant system with ammonium polyphosphate. Upon combustion, an intumescent char layer formed on the EVA surface, significantly reducing the heat release rate and total heat release during combustion and improving flame retardancy.

[0040] The cross-linked polymer of the ammonium polyphosphate microcapsule wall of Comparative Example 2 does not contain triazine rings and multiple high-carbon benzene ring structures, and no expansion flame retardant system is formed, resulting in a large peak heat release rate and total heat release of EVA and poor flame retardant performance.

[0041] The cross-linked polymer of the ammonium polyphosphate microcapsule wall of Comparative Example 3 contains triazine rings and multiple high-carbon benzene ring structures, which form an intumescent flame retardant system with ammonium polyphosphate, reduce the heat release rate and total heat release during EVA combustion, and improve the flame retardant performance.

[0042] The present invention also provides the following embodiment, in which a flame-retardant film containing flame-retardant EVA is composed of a flame-retardant PET polyester layer, a polyurethane layer, and a flame-retardant EVA layer; the preparation method of the flame-retardant film is as follows: flame-retardant polyethylene terephthalate is biaxially stretched to form a flame-retardant PET polyester layer, and corona treatment is performed by a corona machine; polyurethane is then sprayed on one side of the flame-retardant PET polyester layer, and the polyurethane layer is formed after baking and curing; the flame-retardant EVA is then melted, cast and coated on the polyurethane layer by a casting machine, and finally cooled, rolled, and wound by an extruder roller to obtain a flame-retardant film containing flame-retardant EVA.

[0043] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A flame retardant film containing flame retardant EVA, characterized in that: The flame retardant film includes flame retardant EVA; the preparation method of the flame retardant EVA is: (1) Add ammonium polyphosphate to ethanol, disperse by ultrasonication, add N,N-dimethylformamide as a cosolvent, 2,4,6-tris[4-(mercaptoacetamide)phenyl]-1,3,5-triazine, divinyl adipate, and an alkali catalyst, stir and react in a nitrogen atmosphere, remove the solvent by vacuum distillation, wash, and dry to obtain ammonium polyphosphate microcapsules; (2) Ethylene-vinyl acetate copolymer and ammonium polyphosphate microcapsules are mixed, then blended and extruded in a twin-screw extruder, and pelletized to obtain flame-retardant EVA.

2. The flame retardant film containing flame retardant EVA according to claim 1, characterized in that: The reaction temperature of (1) is 15-25°C, and the reaction time is 2-3 hours.

3. The flame retardant film containing flame retardant EVA according to claim 1, characterized in that: The mass ratio of ammonium polyphosphate, 2,4,6-tris[4-(mercaptoacetamide)phenyl]-1,3,5-triazine, divinyl adipate and base catalyst in (1) is 100:(6-10):(3.1-5.2):(0.1-0.16).

4. The flame retardant film containing flame retardant EVA according to claim 3, characterized in that: The base catalyst includes triethylamine.

5. The flame retardant film containing flame retardant EVA according to claim 1, characterized in that: The mass ratio of ethylene-vinyl acetate copolymer and ammonium polyphosphate microcapsules in (2) is 100:(30-70).

6. The flame retardant film containing flame retardant EVA according to claim 1, characterized in that: The temperature of zones 1-6 of the twin-screw extruder in (2) is 140-175°C, and the screw speed is 100-200 r / min.

7. The flame retardant film containing flame retardant EVA according to claim 3, characterized in that: The preparation method of 2,4,6-tris[4-(mercaptoacetamide)phenyl]-1,3,5-triazine comprises: adding 2,4,6-tris(4-aminophenyl)-1,3,5-triazine, mercaptoacetic acid, N,N-diisopropylethylamine, and 2-(7-azabenzotriazole)-N,N,N',N'-tetramethyluronium hexafluorophosphate to N,N-dimethylformamide; after the reaction, removing the solvent by distillation under reduced pressure; and recrystallizing the product after washing to obtain 2,4,6-tris[4-(mercaptoacetamide)phenyl]-1,3,5-triazine.

8. The flame retardant film containing flame retardant EVA according to claim 6, characterized in that: The molar ratio of the 2,4,6-tris(4-aminophenyl)-1,3,5-triazine, thioglycolic acid, N,N-diisopropylethylamine, and 2-(7-azabenzotriazole)-N,N,N',N'-tetramethyluronium hexafluorophosphate is 1:(3-3.6):(6-6.9):(6-6.9).

9. A method for preparing a flame retardant film containing flame retardant EVA according to any one of claims 1 to 8, characterized in that: The flame-retardant film containing flame-retardant EVA consists of a flame-retardant PET polyester layer, a polyurethane layer, and a flame-retardant EVA layer. The preparation method of the flame-retardant film comprises: biaxially stretching flame-retardant polyethylene terephthalate to form a flame-retardant PET polyester layer, and corona treating it with a corona machine; then spraying polyurethane on one side of the flame-retardant PET polyester layer, and baking and curing it to form a polyurethane layer; then melting the flame-retardant EVA, casting it with a casting machine and coating it on the polyurethane layer, and finally cooling it with an extruder roller, rolling it up, and rewinding it to obtain the flame-retardant film containing flame-retardant EVA.