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

Abstract

The application relates to the technical field of EVA, and discloses 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. 2,4,6-tris[4-(mercaptoacetamide)phenyl]-1,3,5-triazine and diethylene adipate are subjected to a mercapto-alkene click reaction, a polymer capsule wall is crosslinked on the surface of ammonium polyphosphate to obtain ammonium polyphosphate microcapsules, then the ammonium polyphosphate microcapsules are melt-blended with EVA resin to obtain flame-retardant EVA. The crosslinked polymer of the capsule wall of the ammonium polyphosphate microcapsules contains a triazine ring and multiple benzene ring structures with high carbon content, and forms an intumescent flame-retardant system with ammonium polyphosphate, thereby improving the flame-retardant property of the EVA. The compatibility of the ammonium polyphosphate microcapsules with the EVA is good, the influence of the microcapsules on the mechanical property of the EVA is reduced, and the EVA maintains good mechanical strength.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of EVA, in particular to a flame-retardant film containing flame-retardant EVA and a preparation method thereof. BACKGROUND

[0002] EVA (ethylene-vinyl acetate copolymer) has good toughness, impact resistance, low-temperature resistance and other properties. EVA can be compounded with polyethylene terephthalate, polyurethane, polyethylene and other materials to form a multi-layer composite film material with excellent performance, which is widely used in packaging, plastic packaging, automobile industry, agriculture and other fields. Ordinary EVA material is easy to burn in the presence of fire, which poses a great safety hazard.

[0003] Adding flame retardants such as ammonium polyphosphate to EVA material can improve the flame retardant properties of EVA and its composite film material. However, ammonium polyphosphate has high hygroscopicity, poor hydrolysis resistance and is prone to agglomeration, which can affect the flame retardant properties of the material. Coating ammonium polyphosphate with hydrophobic microcapsules can improve its hydrolysis resistance and other properties, such as melamine resin microcapsules, epoxy resin microcapsules, unsaturated polyester resin microcapsules, etc. However, the compatibility of the capsule wall of these microcapsules with EVA is poor, which has a great impact on the mechanical properties of the material. SUMMARY

[0004] The present application provides a flame-retardant film containing flame-retardant EVA, which solves the problem of poor flame retardant properties of EVA and its composite film material.

[0005] To achieve the above-mentioned purpose, the technical solution adopted by the present application 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 includes: preparing the flame-retardant PET polyester layer by biaxially stretching flame-retardant polyethylene terephthalate and treating it by corona machine; then spraying polyurethane on one side of the flame-retardant PET polyester layer, and forming the polyurethane layer after baking and curing; then melting the flame-retardant EVA, casting it by a casting machine and coating it on the polyurethane layer, and finally cooling and rolling by an extruder roller, and winding to obtain the flame-retardant film containing flame-retardant EVA.

[0006] The preparation method of the flame-retardant EVA is as follows:

[0007] (1) Add ammonium polyphosphate to ethanol and disperse by ultrasonic, add N,N-dimethylformamide as a solvent, 2,4,6-tris[4-(mercaptoacetamide)phenyl]-1,3,5-triazine, diethylene adipate and alkali catalyst, stir and react in a nitrogen atmosphere, remove the solvent by reduced pressure distillation, wash with ethanol and water, and dry to obtain ammonium polyphosphate microcapsules.

[0008] (2) mixing ethylene-vinyl acetate copolymer and ammonium polyphosphate microcapsule, then blending and extruding in a twin-screw extruder, pelletizing to obtain flame-retardant EVA.

[0009] Preferably, the temperature of the reaction is 15-25℃, and the reaction time is 2-3h.

[0010] 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).

[0011] Preferably, the base catalyst comprises triethylamine.

[0012] Preferably, the mass ratio of ethylene-vinyl acetate copolymer and ammonium polyphosphate microcapsule in (2) is 100:(30-70).

[0013] Preferably, the temperature of the 1-6 zones of the twin-screw extruder in (2) is 140-175℃, and the screw rotation speed is 100-200r / min.

[0014] Preferably, the preparation method of 2,4,6-tris[4-(mercaptoacetamide)phenyl]-1,3,5-triazine is as follows: adding 2,4,6-tris(4-aminophenyl)-1,3,5-triazine, mercaptoacetic acid, N,N-diisopropyl ethylamine, and 2-(7-azabenzotriazol)-N,N,N',N'-tetramethyluronium hexafluorophosphate (HATU) into N,N-dimethylformamide, removing the solvent by distillation under reduced pressure after the reaction, washing with water, recrystallizing the product in dichloromethane to obtain 2,4,6-tris[4-(mercaptoacetamide)phenyl]-1,3,5-triazine. The reaction formula is as follows:

[0015] .

[0016] Preferably, the molar ratio of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine, mercaptoacetic acid, N,N-diisopropyl ethylamine, and 2-(7-azabenzotriazol)-N,N,N',N'-tetramethyluronium hexafluorophosphate is 1:(3-3.6):(6-6.9):(6-6.9).

[0017] (III) Beneficial technical effects: The application utilizes triethylamine as a catalyst, carries out thiol-alkene click reaction on 2,4,6-tris[4-(mercaptoacetamide)phenyl]-1,3,5-triazine containing three mercapto groups and diethylenyl adipate containing two alkenyl groups, crosslinks to generate a polymer capsule wall on the surface of ammonium polyphosphate, obtains ammonium polyphosphate microcapsules, and then is melt blended with EVA resin to obtain flame-retardant EVA, the crosslinked polymer of the capsule wall of the ammonium polyphosphate microcapsule contains acetic acid ethyl ester structural units similar to EVA, ), so that the compatibility of the ammonium polyphosphate microcapsule with EVA is good, the influence of the microcapsule on the mechanical properties of EVA is reduced, and the EVA maintains good tensile strength and impact strength.

[0018] The crosslinked polymer of the capsule wall of the ammonium polyphosphate microcapsule of the application contains a triazine ring and a plurality of benzene ring structures with high carbon content, forms an intumescent flame-retardant system with ammonium polyphosphate, forms an intumescent carbon layer on the surface of EVA during combustion, significantly reduces the heat release rate and total heat release amount of EVA during combustion, and improves the flame-retardant performance.

[0019] The application further forms a multilayer composite film by using flame-retardant polyethylene terephthalate, a polyurethane adhesive layer and flame-retardant EVA, and uses the flame-retardant EVA layer to improve the overall flame-retardant performance of the composite film. DETAILED DESCRIPTION

[0020] The application will be described in detail below in combination with specific examples. The following examples will help those skilled in the art to further understand the application.

[0021] Ethylene-vinyl acetate copolymer, trade name DuPont 210W, purchased from Guangzhou Hongcheng Plastic Co., Ltd. Flame-retardant

[0022] Example 1

[0023] (1) 50 mmol of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine, 180 mmol of mercaptoacetic acid, 330 mmol of N,N-diisopropylethylamine, 330 mmol of 2-(7-azabenzotriazole)-N,N,N',N'-tetramethyluronium hexafluorophosphate are added to 200 mL of N,N-dimethylformamide, and reacted at 25°C for 12 h, the solvent is removed by distillation under reduced pressure, washed with water, and the product is recrystallized in dichloromethane to obtain 2,4,6-tris[4-(mercaptoacetamide)phenyl]-1,3,5-triazine.

[0024] (2) 300 g of ammonium polyphosphate was added to 1 L of ethanol and dispersed by ultrasonic, 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 were added, and the reaction was stirred under a nitrogen atmosphere. The solvent was removed by distillation under reduced pressure, and the product was washed with ethanol and water and dried to obtain ammonium polyphosphate microcapsules.

[0025] (3) 1 kg of ethylene-vinyl acetate copolymer and 0.3 kg of ammonium polyphosphate microcapsules were mixed and then blended and extruded in a twin-screw extruder, with the temperature of zones 1 to 6 being 140°C, 160°C, 170°C, 175°C, 175°C, and 170°C, and the screw rotation speed being 100 r / min. The product was pelletized to obtain flame-retardant EVA.

[0026] Comparative Example 1

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

[0028] Comparative Example 2

[0029] (1) 300 g of ammonium polyphosphate was added to 1 L of ethanol and dispersed by ultrasonic, 200 mL of N,N-dimethylformamide as a cosolvent, 11.13 g (31.25 mmol) of trimethylolpropane tris(mercaptoacetate) (CAS No. 10193-96-1), 9.3 g of divinyl adipate, and 0.3 g of triethylamine were added, and the reaction was stirred under a nitrogen atmosphere. The solvent was removed by distillation under reduced pressure, and the product was washed with ethanol and water and dried to obtain ammonium polyphosphate microcapsules.

[0030] (2) 1 kg of ethylene-vinyl acetate copolymer and 0.3 kg of ammonium polyphosphate microcapsules were mixed and then blended and extruded in a twin-screw extruder, with the temperature of zones 1 to 6 being 140°C, 160°C, 170°C, 175°C, 175°C, and 170°C, and the screw rotation speed being 100 r / min. The product was pelletized to obtain flame-retardant EVA.

[0031] Comparative Example 3

[0032] (1) 300 g of ammonium polyphosphate was added to 1 L of ethanol and dispersed by ultrasonic, 200 mL of N,N-dimethylformamide as a cosolvent, 18 g of 2,4,6-tris[4-(mercaptoacetamide)phenyl]-1,3,5-triazine (the same as the preparation method of 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 the reaction was stirred under a nitrogen atmosphere. The solvent was removed by distillation under reduced pressure, washed with ethanol and water, and dried to obtain ammonium polyphosphate microcapsules.

[0033] (2) 1 kg of ethylene-vinyl acetate copolymer and 0.3 kg of ammonium polyphosphate microcapsules were mixed and then blended and extruded in a twin-screw extruder, with the temperature of zones 1 to 6 being 140°C, 160°C, 170°C, 175°C, 175°C, and 170°C, and the screw rotation speed being 100 r / min. The extrudate was pelletized to obtain a flame-retardant EVA.

[0034] Example 2

[0035] (1) 50 mmol of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine, 150 mmol of mercaptoacetic acid, 300 mmol of N,N-diisopropylethylamine, and 300 mmol of 2-(7-azabenzotriazol)-N,N,N',N'-tetramethyluronium hexafluorophosphate were added to 200 mL of N,N-dimethylformamide, and the reaction was performed at 30°C for 12 h. The solvent was removed by distillation under reduced pressure, washed with water, and the product was recrystallized in dichloromethane to obtain 2,4,6-tris[4-(mercaptoacetamide)phenyl]-1,3,5-triazine.

[0036] (2) 300 g of ammonium polyphosphate was added to 1.2 L of ethanol and dispersed by ultrasonic, 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 adipic acid divinyl ester, and 0.48 g of triethylamine were added, and the reaction was stirred under a nitrogen atmosphere. The solvent was removed by distillation under reduced pressure, washed with ethanol and water, and dried to obtain ammonium polyphosphate microcapsules.

[0037] (3) 1 kg of ethylene-vinyl acetate copolymer and 0.5 kg of ammonium polyphosphate microcapsules were mixed and then blended and extruded in a twin-screw extruder, with the temperature of zones 1 to 6 being 140°C, 160°C, 170°C, 175°C, 175°C, and 170°C, and the screw rotation speed being 200 r / min. The extrudate was pelletized to obtain a flame-retardant EVA.

[0038] Example 3

[0039] (1) 50 mmol 2,4,6-tris(4-aminophenyl)-1,3,5-triazine, 165 mmol mercaptoacetic acid, 345 mmol N,N-diisopropylethylamine, 345 mmol 2-(7-azabenzotriazol)-N,N,N',N'-tetramethyluronium hexafluorophosphate were added into 300 mL N,N-dimethylformamide, and the reaction was carried out at 15 °C for 18 h. The solvent was removed by distillation under reduced pressure, and the product was washed with water. The product was recrystallized in dichloromethane to obtain 2,4,6-tris[4-(mercaptoacetamide)phenyl]-1,3,5-triazine.

[0040] (2) 300 g ammonium polyphosphate was added into 1.2 L ethanol and dispersed by ultrasonic. 200 mL N,N-dimethylformamide, 23.7 g 2,4,6-tris[4-(mercaptoacetamide)phenyl]-1,3,5-triazine, 12.4 g adipic acid divinyl ester, and 0.4 g triethylamine were added into the mixture. The reaction was carried out under stirring in a nitrogen atmosphere. The solvent was removed by distillation under reduced pressure, and the product was washed with ethanol and water, and dried to obtain ammonium polyphosphate microcapsules.

[0041] (3) 1 kg ethylene-vinyl acetate copolymer and 0.7 kg ammonium polyphosphate microcapsules were mixed, and then blended and extruded in a twin-screw extruder. The temperature of the first to sixth zones was 140 °C, 160 °C, 170 °C, 175 °C, 175 °C, and 170 °C, respectively. The screw rotation speed was 200 r / min. The extrudate was pelletized to obtain flame-retardant EVA.

[0042] The flame-retardant EVA was molded by a flat vulcanizing machine at a temperature of 140 °C and a pressure of 10 MPa. The tensile properties were tested according to the standard GB / T 1040.1-2018. The impact strength was tested according to the standard GB / T 1843-2008.

[0043] Table 1 Mechanical properties of flame-retardant EVA

[0044] Tensile strength (MPa) 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

[0045] It was found through tests that the addition of ammonium polyphosphate to EVA in Comparative Example 1 resulted in poor compatibility between the two, which affected the mechanical properties of EVA and led to low tensile strength and impact strength of EVA. In Example 1, the crosslinked polymer of 2,4,6-tris[4-(mercaptoacetamide)phenyl]-1,3,5-triazine and adipic acid divinyl ester was used as the capsule wall of ammonium polyphosphate, and the crosslinked polymer of the capsule wall contained acetic acid ethyl ester structural units similar to EVA (CH2C(O)OCH2CH3) , which resulted in good compatibility between the ammonium polyphosphate microcapsules and EVA, reduced the influence of the microcapsules on the mechanical properties of EVA, and enabled EVA to maintain good tensile strength and impact strength.

[0046] The cross-linked polymer of trimethylolpropane tris (mercaptoacetate) and adipic acid divinyl ester as the capsule wall of ammonium polyphosphate microcapsule in Comparative Example 2 contains ethyl acetate structural unit, which has good compatibility with EVA and less influence on the mechanical properties of EVA, so that the tensile strength and impact strength of EVA can be maintained at a high level.

[0047] The cross-linked polymer of 2,4,6-tris [4- (mercaptoacetamide) phenyl] -1,3,5-triazine and N,N-methylene bisacrylamide as the capsule wall of ammonium polyphosphate microcapsule in Comparative Example 3 does not contain ethyl acetate structural unit, which has poor compatibility with EVA, resulting in low tensile strength and impact strength of EVA.

[0048] The combustion performance of EVA was tested by a cone calorimeter, the heat radiation power was 35 kW / m 2 , and the sample size was 10 cm x 10 cm x 0.4 cm. The blank sample was EVA without ammonium polyphosphate.

[0049] Table 2 Flame retardant performance of EVA

[0050] Heat release rate peak (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

[0051] The peak heat release rate and total heat release of the blank sample of EVA without ammonium polyphosphate were very large, and the flame retardant performance was poor. The peak heat release rate and total heat release of Comparative Example 1 with ammonium polyphosphate were significantly reduced. The ammonium polyphosphate microcapsules were added in Examples 1-3, and the cross-linked polymer of the capsule wall contained triazine ring and multiple high-carbon content benzene ring structure, forming an intumescent flame retardant system with ammonium polyphosphate, forming an intumescent carbon layer on the surface of EVA during combustion, significantly reducing the heat release rate and total heat release of EVA during combustion, and improving the flame retardant performance.

[0052] The cross-linked polymer of the ammonium polyphosphate microcapsule capsule wall in Comparative Example 2 did not contain triazine ring and multiple high-carbon content benzene ring structure, and did not form an intumescent flame retardant system, resulting in a large peak heat release rate and total heat release of EVA, and poor flame retardant performance.

[0053] The cross-linked polymer of the ammonium polyphosphate microcapsule capsule wall in Comparative Example 3 contained triazine ring and multiple high-carbon content benzene ring structure, forming an intumescent flame retardant system with ammonium polyphosphate, reducing the heat release rate and total heat release of EVA during combustion, and improving the flame retardant performance.

[0054] The application further provides the following embodiment, the flame-retardant film containing the 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: the flame-retardant polyethylene terephthalate is biaxially stretched to form the flame-retardant PET polyester layer, and then the flame-retardant PET polyester layer is treated by a corona machine; then the polyurethane is sprayed on one side of the flame-retardant PET polyester layer, and the polyurethane layer is formed after baking and curing; then the flame-retardant EVA is melted, cast by a casting machine and coated on the polyurethane layer, finally cooled and rolled by an extruder roller, and wound to obtain the flame-retardant film containing the flame-retardant EVA.

[0055] The above embodiment is the preferred embodiment of the application, but the embodiment of the application is not limited by the above embodiment, and any change, modification, replacement, combination, simplification made without departing from the spirit and principle of the application should be an equivalent replacement mode, and all are included in the protection scope of the application.

Claims

1. A flame retardant film comprising flame retardant EVA, characterized in that, The flame-retardant film comprises flame-retardant EVA; the preparation method of the flame-retardant EVA is: (1) adding ammonium polyphosphate into ethanol, dispersing by ultrasonic, adding N,N-dimethylformamide as a solvent, 2,4,6-tris[4-(mercaptoacetamide) phenyl]-1,3,5-triazine, diethylene adipate, and an alkali catalyst, stirring and reacting in a nitrogen atmosphere, removing the solvent by distillation under reduced pressure, washing, and drying to obtain ammonium polyphosphate microcapsules; (2) mixing ethylene-vinyl acetate copolymer and ammonium polyphosphate microcapsules, and then blending and extruding in a double-screw extruder to obtain flame-retardant EVA; The mass ratio of ethylene-vinyl acetate copolymer to ammonium polyphosphate microcapsules in the step (2) is 100: (30-50).

2. The flame retardant film comprising flame retardant EVA according to claim 1, characterized in that, The reaction temperature in the step (1) is 15-25℃, and the reaction time is 2-3h.

3. The flame retardant film comprising flame retardant EVA as claimed in claim 1 wherein, The mass ratio of ammonium polyphosphate, 2,4,6-tris[4-(mercaptoacetamide) phenyl]-1,3,5-triazine, diethylene adipate, and the alkali catalyst in the step (1) is 100: (6-10): (3.1-5.2): (0.1-0.16).

4. The flame retardant film comprising flame retardant EVA according to claim 3, characterized in that, The alkali catalyst comprises triethylamine.

5. The flame retardant film comprising flame retardant EVA as claimed in claim 1 wherein, The temperature of the 1-6 zones of the double-screw extruder in the step (2) is 140-175℃, and the screw rotation speed is 100-200r / min.

6. The flame retardant film comprising flame retardant EVA as claimed in claim 3, wherein, The preparation method of the 2,4,6-tris[4-(mercaptoacetamide) phenyl]-1,3,5-triazine is: adding 2,4,6-tris(4-aminophenyl)-1,3,5-triazine, mercaptoacetic acid, N,N-diisopropylethylamine, and 2-(7-azabenzotriazol)-N,N,N',N'-tetramethyluronium hexafluorophosphate into N,N-dimethylformamide, removing the solvent by distillation under reduced pressure after reaction, washing, and recrystallizing the product to obtain 2,4,6-tris[4-(mercaptoacetamide) phenyl]-1,3,5-triazine.

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

8. A process for the preparation of a flame retardant film comprising flame retardant EVA as claimed in any one of claims 1 to 7, characterized in that, The 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 comprises: preparing the flame-retardant PET polyester layer by biaxially stretching flame-retardant polyethylene terephthalate, and treating the flame-retardant PET polyester layer by a corona machine; then spraying polyurethane on one side of the flame-retardant PET polyester layer, and forming the polyurethane layer after baking and curing; then melting the flame-retardant EVA, casting the flame-retardant EVA on the polyurethane layer by a casting machine, and finally cooling and rolling the flame-retardant EVA by an extruder roller, and winding to obtain the flame-retardant film containing flame-retardant EVA.