Flame retardant polyester film and preparation method thereof

Abstract

The present invention relates to the technical field of polyester films, and in particular to a flame-retardant polyester film and a preparation method thereof. The PET polyester film used for the protective film of electronic products does not have flame retardancy. In view of the above problems, the present invention provides a flame-retardant polyester film, including a polyester substrate and an anti-reflective flame-retardant coating on the surface of the polyester substrate. The present invention not only adds poly [hydroxyethyl methacrylate-co-cyclotriphosphazene-co-(3,4-dihydroxybenzoic acid)] oligomers to the anti-reflective flame-retardant coating raw material formula, but also adds vinyl-POSS, both of which have a good synergistic flame retardant effect, and the addition of vinyl-POSS significantly improves the polar oxygen index of the flame-retardant polyester film.

Description

Technical Field

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

[0002] Biaxially oriented PET polyester film is lightweight and transparent, and is widely used in the field of protective films for electronic products. However, PET is a flammable polymer, which releases a large amount of smoke and toxic gases when burned, and has continuous melting and dripping phenomena, which not only harms the environment, but also poses a huge threat to people's lives and property safety.

[0003] Therefore, in order to expand the application range of PET polyester film, it is very important to research and develop flame-retardant polyester materials. Studies have shown that whether it is coated on the surface of PET polyester film or added to its coating formula system, it is easy to reduce the light transmittance of PET polyester film. Therefore, while maintaining the good light transmittance of PET polyester film, giving PET polyester film good flame retardancy has become one of the key issues that researchers in this field focus on. Summary of the invention

[0004] The problem in the prior art is that the PET polyester film used as a protective film for electronic products does not have flame retardancy. In view of the above problem, the present invention provides a flame retardant polyester film, comprising a polyester substrate and an anti-reflection flame retardant coating on the surface of the polyester substrate, wherein the anti-reflection flame retardant coating is a cross-linked copolymer formed by polyurethane acrylate and poly [hydroxyethyl methacrylate-co-cyclotriphosphazene-co-(3,4-dihydroxybenzoic acid)] oligomer, a reactive diluent, and vinyl-POSS.

[0005] Specifically, the polyester substrate is a biaxially oriented PET polyester film.

[0006] Specifically, the anti-reflection flame retardant coating comprises the following raw materials by mass ratio:

[0007]

[0008] Specifically, the polyurethane acrylate may be at least one of Easepi 864, T20D, and NeoRad U-61.

[0009] Specifically, the poly[hydroxyethyl methacrylate-co-cyclotriphosphazene-co-(3,4-dihydroxybenzoic acid)] oligomer, in its preparation process, uses hydroxyethyl methacrylate, hexachlorocyclotriphosphazene, and 3,4-dihydroxybenzoic acid as reaction monomers, tetrahydrofuran as solvent, triethylamine as acid binding agent, and cuprous chloride as catalyst, and the reaction monomers, acid binding agent, and catalyst are all added to the solvent and mixed, and then reacted in an ice water bath for 4 hours, and then reacted at room temperature for 6 hours, the obtained reaction product is washed with tetrahydrofuran and centrifuged, and the obtained precipitate is vacuum dried at 50°C for 48 hours to obtain the poly[hydroxyethyl methacrylate-co-cyclotriphosphazene-co-(3,4-dihydroxybenzoic acid)] oligomer.

[0010] Specifically, the active diluent includes at least one of 2-phenoxyethyl acrylate, 2-acrylate-(1-methyl-1,2-ethylene)bis(β-methoxyethyl) ester, and tetrahydrofurfuryl acrylate.

[0011] Specifically, the flame retardant polyester film comprises the following preparation steps:

[0012] (1) adding a photoinitiator, a reactive diluent, a vinyl POSS monomer, and poly[hydroxyethyl methacrylate-co-cyclotriphosphazene-co-(3,4-dihydroxybenzoic acid)] into a reactor according to the formula amount, and ultrasonically mixing them uniformly, and then adding polyurethane acrylate, and ultrasonically mixing them uniformly in the dark to obtain a polyester film coating;

[0013] (2) applying the polyester film coating obtained in step (1) to the surface of the polyester substrate and curing it under ultraviolet light, wherein the wavelength of the photocuring is 350 nm and the intensity of the ultraviolet light is 200 mw / cm 2 After light curing is completed, a flame retardant polyester film is obtained.

[0014] Beneficial Effects

[0015] (1) The flame-retardant polyester film prepared by the present invention not only has good flame retardant properties, but also has excellent light transmittance, which is as high as more than 90%;

[0016] (2) The present invention not only adds poly [hydroxyethyl methacrylate-co-cyclotriphosphazene-co-(3,4-dihydroxybenzoic acid)] oligomer but also adds vinyl-POSS to the raw material formula of the anti-reflection flame retardant coating. The two have a good synergistic flame retardant effect. The addition of vinyl-POSS significantly improves the polar oxygen index of the flame retardant polyester film.

[0017] (3) The silicon-oxygen bonds in the vinyl-POSS structure in the raw material formula of the anti-reflection flame-retardant coating of the present invention help to improve the light transmittance of the polyester film, and the POSS cage structure in the vinyl-POSS will produce refraction, which can further increase the light transmittance of the polyester film;

[0018] (4) The self-prepared poly[hydroxyethyl methacrylate-co-cyclotriphosphazene-co-(3,4-dihydroxybenzoic acid)] oligomer of the present invention introduces a 3,4-dihydroxybenzoic acid fragment, and the obtained oligomer has a good structural similarity with PET, which helps to further improve the light transmittance and flame retardancy of the flame-retardant polyester film. DETAILED DESCRIPTION

[0019] The poly[hydroxyethyl methacrylate-co-cyclotriphosphazene-co-(3,4-dihydroxybenzoic acid)] oligomer in the following examples of the present invention was prepared according to the following steps:

[0020] 6.51g of hydroxyethyl methacrylate, 0.77g of 3,4-dihydroxybenzoic acid, 6.05g of triethylamine and 0.08g of Cu2Cl2 were added to a 250mL three-necked flask, and 50mL of THF was added at the same time. Under a nitrogen atmosphere, 75mL of THF solution containing 3.5g of hexachlorocyclotriphosphazene was slowly dripped in. The reaction was stirred for 4h in an ice-water bath, and then stirred for 6h at room temperature. The reaction product was washed with tetrahydrofuran and centrifuged, and then the product was vacuum dried at 50°C for 48h to obtain the obtained poly[hydroxyethyl methacrylate-co-cyclotriphosphazene-co-(3,4-dihydroxybenzoic acid)] at 1173cm in the infrared spectrum. -1 The PN absorption peak is at 3426cm -1 The -OH absorption peak is at 2925cm, indicating that the chlorine atom has not completely replaced the hydrogen on the hydroxyl groups of hydroxyethyl methacrylate and 3,4-dihydroxybenzoic acid. -1 The stretching vibration peak of methyl group is 1716cm -1 The absorption peak of C=O is 1635cm -1 The absorption peak of C=C is at 1067-1035cm, indicating the existence of HEMA and PCA structures in the product. -1 The broad peak at is the absorption peak of POC, indicating that poly[hydroxyethyl methacrylate-co-cyclotriphosphazene-co-(3,4-dihydroxybenzoic acid)] has been successfully prepared.

[0021] The vinyl-POSS in the following examples of the present invention has CAS: 69655-76-1.

[0022] The biaxially oriented PET films in the following embodiments of the present invention were purchased from Jiangsu Yuxing Film Technology Co., Ltd., and the model number is CY20.

[0023] The polyurethane acrylate used in the following examples of the present invention is Agisyn 271, purchased from Shanghai Youming Chemical Co., Ltd.

[0024] Example 1

[0025] A flame-retardant polyester film, comprising a polyester substrate and an anti-reflection flame-retardant coating coated on the surface of the polyester substrate, wherein the polyester substrate is a biaxially stretched PET film with a thickness of 150 μm, the thickness of the anti-reflection flame-retardant coating is 40 μm, and the anti-reflection flame-retardant coating, by mass ratio, is composed of the following raw materials:

[0026]

[0027] The flame retardant polyester film is prepared according to the following steps:

[0028] (1) adding a photoinitiator, a reactive diluent, a vinyl POSS monomer, and poly[hydroxyethyl methacrylate-co-cyclotriphosphazene-co-(3,4-dihydroxybenzoic acid)] into a reactor according to the formula amount, and mixing them evenly with ultrasound, and then adding polyurethane acrylate, and mixing evenly with ultrasound in the dark to obtain a polyester film coating;

[0029] (2) applying the polyester film coating obtained in step (1) to the surface of the polyester substrate and curing it under ultraviolet light, wherein the wavelength of the photocuring is 350 nm and the intensity of the ultraviolet light is 200 mw / cm 2 After light curing is completed, a flame retardant polyester film is obtained.

[0030] Example 2

[0031] A flame-retardant polyester film, comprising a polyester substrate and an anti-reflection flame-retardant coating coated on the surface of the polyester substrate, wherein the polyester substrate is a biaxially stretched PET film with a thickness of 150 μm, the thickness of the anti-reflection flame-retardant coating is 40 μm, and the anti-reflection flame-retardant coating, by mass ratio, is composed of the following raw materials:

[0032]

[0033] The flame retardant polyester film is prepared according to the following steps:

[0034] (1) adding a photoinitiator, a reactive diluent, and a vinyl POSS monomer into a reactor according to the formula amount, and uniformly mixing them by ultrasonication, and then adding polyurethane acrylate, and uniformly mixing them by ultrasonication in the dark to obtain a polyester film coating;

[0035] (2) applying the polyester film coating obtained in step (1) to the surface of the polyester substrate and curing it under ultraviolet light, wherein the wavelength of the photocuring is 350 nm and the intensity of the ultraviolet light is 200 mw / cm 2 After light curing is completed, a flame retardant polyester film is obtained.

[0036] Example 3

[0037] A flame-retardant polyester film, comprising a polyester substrate and an anti-reflection flame-retardant coating coated on the surface of the polyester substrate, wherein the polyester substrate is a biaxially stretched PET film with a thickness of 150 μm, the thickness of the anti-reflection flame-retardant coating is 40 μm, and the anti-reflection flame-retardant coating, by mass ratio, is composed of the following raw materials:

[0038]

[0039] The flame retardant polyester film is prepared according to the following steps:

[0040] (1) adding a photoinitiator, a reactive diluent, and poly[hydroxyethyl methacrylate-co-cyclotriphosphazene-co-(3,4-dihydroxybenzoic acid)] into a reactor according to the formula amount, and mixing them evenly by ultrasonication, and then adding polyurethane acrylate, and mixing evenly by ultrasonication in the dark to obtain a polyester film coating;

[0041] (2) applying the polyester film coating obtained in step (1) to the surface of the polyester substrate and curing it under ultraviolet light, wherein the wavelength of the photocuring is 350 nm and the intensity of the ultraviolet light is 200 mw / cm 2 After light curing is completed, a flame retardant polyester film is obtained.

[0042] Example 4

[0043] A flame-retardant polyester film, comprising a polyester substrate and an anti-reflection flame-retardant coating coated on the surface of the polyester substrate, wherein the polyester substrate is a biaxially stretched PET film with a thickness of 150 μm, the thickness of the anti-reflection flame-retardant coating is 40 μm, and the anti-reflection flame-retardant coating, by mass ratio, is composed of the following raw materials:

[0044]

[0045] The flame retardant polyester film is prepared according to the following steps:

[0046] (1) adding a photoinitiator, a reactive diluent, and poly[hydroxyethyl methacrylate-co-cyclotriphosphazene-co-(3,4-dihydroxybenzoic acid)] into a reactor according to the formula amount, and mixing them evenly by ultrasonication, and then adding polyurethane acrylate, and mixing evenly by ultrasonication in the dark to obtain a polyester film coating;

[0047] (2) applying the polyester film coating obtained in step (1) to the surface of the polyester substrate and curing it under ultraviolet light, wherein the wavelength of the photocuring is 350 nm and the intensity of the ultraviolet light is 200 mw / cm 2 After light curing is completed, a flame retardant polyester film is obtained.

[0048] Comparative Example 1 is a biaxially stretched PET film with a thickness of 150 μm.

[0049] Comparative Example 2 is the same as Example 1, except that the functional monomer vinyl POSS and poly[hydroxyethyl methacrylate-co-cyclotriphosphazene-co-(3,4-dihydroxybenzoic acid)] oligomer are not added to the raw materials of the anti-transmittance flame-retardant coating of Comparative Example 2.

[0050] Comparative Example 3 is the same as Example 1, except that the functional monomer vinyl-POSS is not added to the raw material of the anti-transmittance flame-retardant coating of Comparative Example 3.

[0051] Comparative Example 4 is the same as Example 1, except that the anti-transmittance flame-retardant coating raw material of Comparative Example 4 does not contain poly[hydroxyethyl methacrylate-co-cyclotriphosphazene-co-(3,4-dihydroxybenzoic acid)] oligomer.

[0052] Comparative Example 5 is the same as Example 1, except that, in Comparative Example 5, the poly[hydroxyethyl methacrylate-co-cyclotriphosphazene-co-(3,4-dihydroxybenzoic acid)] oligomer is replaced with a flame retardant oligomer, and the preparation method thereof is as follows:

[0053] Add 6.51g of hydroxyethyl methacrylate, 0.45g of 1,4-butanediol, 6.05g of triethylamine and 0.08g of Cu2Cl2 into a 250mL three-necked flask, and add 50mL of THF at the same time. Under a nitrogen atmosphere, slowly drop 75mL of THF solution containing 3.5g of hexachlorocyclotriphosphazene. Stir the reaction for 4h in an ice-water bath, and then stir the reaction for 6h at room temperature. Wash the reaction product with tetrahydrofuran and centrifuge it. Then, dry the product in vacuum at 50°C for 48h.

[0054] Performance Testing

[0055] Relevant performance tests were performed on the flame-retardant polyester films obtained in Examples 1-3 of the present invention and Comparative Examples 1-5. The test results are shown in Table 1.

[0056] Light transmittance: The light transmittance of the PET film before and after coating was tested using a WGT-S light transmittance / haze tester.

[0057] Haze: The haze of the PET film before and after coating was tested using a WGT-S transmittance / haze tester.

[0058] The limiting oxygen index was tested on the samples using an HC-2 oxygen index instrument, and the PET film was tested according to the GB / T2046-93 test standard.

[0059] Thermal shrinkage: Tested in accordance with GB / T3519 test standard.

[0060] Table 1

[0061] Test items Light transmittance (%) Haze(%) Limiting oxygen index (%) Thermal shrinkage (%) Example 1 90.5 2.64 22.4 2.12 Example 2 90.3 2.95 21.1 2.23 Example 3 90.7 3.15 20.8 2.29 Example 4 90.8 3.34 20.1 2.35 Comparative Example 1 87.7 4.35 19.6 2.46 Comparative Example 2 89.5 6.89 18.0 2.40 Comparative Example 3 90.0 2.57 21.2 2.38 Comparative Example 4 90.7 3.49 19.9 2.37 Comparative Example 5 90.3 3.12 21.0 2.15

[0062] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technical personnel in this field can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A flame retardant polyester film, comprising a polyester substrate and an anti-reflective flame retardant coating on the surface of the polyester substrate, characterized in that: The anti-reflection flame retardant coating is a cross-linked copolymer formed by polyurethane acrylate, poly[hydroxyethyl methacrylate-co-cyclotriphosphazene-co-(3,4-dihydroxybenzoic acid)] oligomer, reactive diluent, and vinyl-POSS; The anti-reflection flame retardant coating comprises the following raw materials by weight ratio: Polyurethane acrylate 40-80% Poly[hydroxyethyl methacrylate-co-cyclotriphosphazene-co-(3,4-dihydroxybenzoic acid)] oligomer 5-25% Active diluent 5-25% Vinyl-POSS 1-10% Photoinitiator 1-5%; The poly[hydroxyethyl methacrylate-co-cyclotriphosphazene-co-(3,4-dihydroxybenzoic acid)] oligomer comprises hydroxyethyl methacrylate, hexachlorocyclotriphosphazene and 3,4-dihydroxybenzoic acid as reaction monomers, tetrahydrofuran as solvent, triethylamine as acid-binding agent and cuprous chloride as catalyst, the reaction monomers, acid-binding agent and catalyst are added into the solvent and mixed evenly, then reacted in an ice-water bath for 4 hours, and then reacted at room temperature for 6 hours, the obtained reaction product is washed with tetrahydrofuran and centrifuged, and the obtained precipitate is vacuum dried at 50°C for 48 hours to obtain the poly[hydroxyethyl methacrylate-co-cyclotriphosphazene-co-(3,4-dihydroxybenzoic acid)] oligomer.

2. A flame retardant polyester film according to claim 1, characterized in that: The polyester substrate is a biaxially oriented PET polyester film.

3. The flame retardant polyester film according to claim 1, characterized in that: The polyurethane acrylate includes at least one of Easepi 864, T20D, and NeoRad U-61.

4. The flame retardant polyester film according to claim 1, characterized in that: The active diluent includes at least one of 2-phenoxyethyl acrylate, 2-acrylate-(1-methyl-1,2-ethylene)bis(β-methoxyethyl) ester, and tetrahydrofurfuryl acrylate.

5. A method for preparing a flame retardant polyester film according to any one of claims 1 to 4, characterized in that: The method comprises the following preparation steps: (1) adding a photoinitiator, a reactive diluent, a vinyl POSS monomer, and poly[hydroxyethyl methacrylate-co-cyclotriphosphazene-co-(3,4-dihydroxybenzoic acid)] into a reactor according to the formula amount, and ultrasonically mixing them uniformly, and then adding polyurethane acrylate, and ultrasonically mixing them uniformly in the dark to obtain a polyester film coating; (2) coating the polyester film coating obtained in step (1) on a polyester substrate and placing it under ultraviolet light for photocuring. After the photocuring is completed, a flame-retardant polyester film is obtained.

Images