Flame-retardant pet composite label material

Abstract

The present application relates to a kind of flame-retardant PET composite label materials, belong to label material technical field.The present application is with PET as base material by using layer-by-layer assembly process makes mixed slurry uniformly attached on base material, wherein mixed slurry includes flame retardant, inorganic filler, leveling agent, polyvinyl alcohol, inorganic filler is sheet dolomite powder and acicular wollastonite powder composition, under the action of leveling agent, filler is laid on base material and constitutes irregular network structure, aromatic schiff base flame retardant is attached to base material outer layer, solve the mechanical strength weakening problem caused by introducing it into PET segment;Therefore, the inorganic network structure of the present application is built in PET outer layer, improves its tear resistance, simultaneously, the introduction of aromatic schiff base flame retardant and the double flame-retardant structure formed by inorganic filler greatly improve the flame retardancy of composite label material.

Description

Technical Field

[0001] This invention belongs to the field of label material technology and relates to a flame-retardant PET composite label material. Background Technology

[0002] Polyethylene terephthalate (PET), commonly known as polyester, is an unsaturated polyester material composed of elements such as carbon, hydrogen, and oxygen. Currently, most labels used in the electronics, home appliances, battery, and transportation industries are made by coating self-adhesive materials onto plastic film and printing them. Due to the high regularity of polyester, its films are widely used as the substrate for electronic and electrical product labels because of their excellent resistance to water, oil, and chemicals, superior mechanical strength, and certain high-temperature resistance. However, PET is a flammable material with a limiting oxygen index (LOI) between 20% and 22%, usually requiring the addition of flame retardants for improvement. Common halogenated and intumescent flame retardants offer very limited improvement in the flame-retardant effect of PET materials and can also affect the processing performance of PET films. Furthermore, while PET has good mechanical strength and folding endurance, its tear strength is poor.

[0003] Current research has explored the introduction of aromatic Schiff base flame retardants into PET molecular chains. These flame retardants utilize the property of curing during heating to form a highly cross-linked network. During PET combustion, this network rapidly undergoes chemical cross-linking on the PET surface, increasing melt viscosity and suppressing dripping. Furthermore, the fused ring structures generated during cross-linking can quickly burn into carbon, covering the PET surface and achieving flame retardancy. However, as an additive comonomer for modifying PET, this process involves the entire condensation reaction of PET, fundamentally altering the structure of the macromolecules and severely damaging the regularity of PET, thereby weakening its mechanical strength. Moreover, the modification process is cumbersome.

[0004] In summary, this invention proposes a flame-retardant PET composite label material, which is a further optimization based on existing technologies. Summary of the Invention

[0005] This invention relates to a flame-retardant PET composite label material, belonging to the technical field of label materials. The invention uses PET as a substrate and employs a layer-by-layer assembly process to uniformly adhere a mixed slurry to the substrate. The mixed slurry includes a flame retardant, inorganic filler, leveling agent, and polyvinyl alcohol. The inorganic filler is composed of flaky marble powder and needle-like wollastonite powder. Under the action of the leveling agent, the filler spreads evenly on the substrate, forming an irregular network structure. An aromatic Schiff base flame retardant is attached to the outer layer of the substrate, solving the problem of reduced mechanical strength caused by its introduction into the PET chain segments. Therefore, the inorganic network structure constructed on the outer layer of PET in this invention improves its tear resistance. Simultaneously, the introduction of the aromatic Schiff base flame retardant and the dual flame-retardant structure formed by the inorganic filler significantly improve the flame retardancy of the composite label material.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] A flame-retardant PET composite label material, wherein the flame-retardant PET composite label material uses PET as a base material and an outer coating composed of inorganic fillers and an aromatic Schiff base flame retardant, wherein the thickness of the outer coating on the base material is 1.5±0.05, and the inorganic filler is composed of flake mica powder and needle-shaped wollastonite powder in a mass ratio of 1:1-2, wherein the mesh ratio of the flake mica powder to the needle-shaped wollastonite powder is 1:1.25-1.35, and wherein the mesh size of the flake mica powder is 1000 mesh.

[0008] Furthermore, the preparation method of the flame-retardant PET composite label material includes the following steps:

[0009] (1) The inorganic filler is placed in an ethanol solution for ultrasonic treatment, and after centrifugation, the solid is dried to constant weight, which is the pretreated inorganic filler.

[0010] (2) The pretreated inorganic filler is placed in a polyvinyl alcohol solution and ultrasonically dispersed. Then, aromatic Schiff base flame retardant and leveling agent are added and stirred to form a mixed slurry. The pretreated PET substrate is immersed in the mixed slurry, taken out and dried at low temperature, and then immersed in the mixed slurry again. After being taken out and dried at low temperature, it is heated and cured. After cooling, flame-retardant PET composite label material is obtained.

[0011] Further, in step (1), the solid-liquid ratio of the inorganic filler to the ethanol solution is 3-5g:50-100mL, wherein the mass fraction of the ethanol solution is 75%, and the power and time of the ultrasonic treatment are 500-800W and 3-5h, respectively.

[0012] Further, in step (2), the mass ratio between the pretreated inorganic filler, polyvinyl alcohol solution, aromatic Schiff base flame retardant and leveling agent is 1-1.8:16-20:2-3:0.5-0.8, the polyvinyl alcohol solution is formed by mixing polyvinyl alcohol and distilled water at a mass ratio of 1-3:80 at 95°C, and the soaking time is 3-4 minutes.

[0013] Furthermore, in step (2), the temperature and time for low-temperature drying are 40-50℃ and 45-60min, respectively, and the temperature and time for heating and curing are 80-100℃ and 15-20min, respectively.

[0014] Furthermore, the preparation method of the aromatic Schiff base flame retardant is as follows:

[0015] A1: Place anhydrous ethanol in a reaction apparatus under nitrogen gas, add 5-aminoisophthalic acid and mix to dissolve, then add bromobenzaldehyde and anhydrous acetic acid and mix and stir.

[0016] A2: After precipitation, the solid is filtered under vacuum, washed with anhydrous ethanol, and then dried under vacuum to obtain an aromatic Schiff base flame retardant.

[0017] Further, in step A1, the mass ratio of 5-aminoisophthalic acid, anhydrous ethanol, bromobenzaldehyde and anhydrous acetic acid is 8-8.5:360-400:8.5:7-8, and the mixing temperature, time and speed are 85-90℃, 8h and 500-1000r / min, respectively.

[0018] Furthermore, the temperature and time for vacuum drying in step A2 are 85°C and 8-8.5h, respectively.

[0019] The beneficial effects of this invention are:

[0020] 1. This invention uses PET as a substrate and employs a layer-by-layer assembly process to uniformly adhere a mixed slurry to the substrate. The mixed slurry includes a flame retardant, inorganic filler, leveling agent, and polyvinyl alcohol. The inorganic filler is composed of flaky marble powder and needle-like wollastonite powder. Under the action of the leveling agent, the filler spreads evenly on the substrate to form an irregular network structure. An aromatic Schiff base flame retardant is attached to the outer layer of the substrate to solve the problem of reduced mechanical strength caused by its introduction into the PET chain segment. Therefore, the inorganic network structure constructed on the outer layer of PET in this invention improves its tear resistance. At the same time, the introduction of the aromatic Schiff base flame retardant and the dual flame retardant structure formed by the inorganic filler greatly improve the flame retardancy of the composite label material. Detailed Implementation

[0021] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features and effects of the present invention, in conjunction with embodiments, is provided below.

[0022] The flake mica powder involved in this invention was purchased from Lingshou County Wanzhu Mineral Products Co., Ltd., with a particle size of 1000 mesh; the needle-shaped wollastonite powder was purchased from Lingshou County Zhengxu Mineral Products Processing Plant, with a porosity of 10%; the degree of polymerization of polyvinyl alcohol was 1700, and the degree of alcoholysis was ≥88%; the leveling agent was Tigo 270, item number AL525446324986.

[0023] Example 1

[0024] A flame-retardant PET composite label material, wherein the flame-retardant PET composite label material uses PET as the base material and an outer coating composed of inorganic fillers and aromatic Schiff base flame retardants, wherein the thickness of the outer coating on the base material is 1.5±0.05, and the inorganic filler is composed of flake mica powder and needle-shaped wollastonite powder in a mass ratio of 1:1, wherein the mesh ratio of the flake mica powder to the needle-shaped wollastonite powder is 1:1.25, and wherein the mesh size of the flake mica powder is 1000 mesh.

[0025] The preparation method of the flame-retardant PET composite label material includes the following steps:

[0026] (1) The inorganic filler is placed in an ethanol solution for ultrasonic treatment, and after centrifugation, the solid is dried to constant weight, which is the pretreated inorganic filler.

[0027] (2) The pretreated inorganic filler is placed in a polyvinyl alcohol solution and ultrasonically dispersed. Then, aromatic Schiff base flame retardant and leveling agent are added and stirred to form a mixed slurry. The pretreated PET substrate is immersed in the mixed slurry, taken out and dried at low temperature, and then immersed in the mixed slurry again. After being taken out and dried at low temperature, it is heated and cured. After cooling, flame-retardant PET composite label material is obtained.

[0028] In step (1), the solid-liquid ratio of the inorganic filler to the ethanol solution is 3g:50mL, wherein the mass fraction of the ethanol solution is 75%, and the power and time of the ultrasonic treatment are 500W and 3h, respectively.

[0029] In step (2), the mass ratio of the pretreated inorganic filler, polyvinyl alcohol solution, aromatic Schiff base flame retardant and leveling agent is 1:16:2:0.5. The polyvinyl alcohol solution is formed by mixing polyvinyl alcohol and distilled water at a mass ratio of 1:80 at 95°C. The soaking time is 3 minutes.

[0030] In step (2), the temperature and time for low-temperature drying are 40°C and 45 min, respectively, and the temperature and time for heating and curing are 80°C and 15 min, respectively.

[0031] The preparation method of the aromatic Schiff base flame retardant is as follows:

[0032] A1: Place anhydrous ethanol in a reaction apparatus under nitrogen gas, add 5-aminoisophthalic acid and mix to dissolve, then add bromobenzaldehyde and anhydrous acetic acid and mix and stir.

[0033] A2: After precipitation, the solid is filtered under vacuum, washed with anhydrous ethanol, and then dried under vacuum to obtain an aromatic Schiff base flame retardant.

[0034] In step A1, the mass ratio of 5-aminoisophthalic acid, anhydrous ethanol, bromobenzaldehyde, and anhydrous acetic acid is 8:360:8.5:7, and the mixing temperature, time, and speed are 85℃, 8h, and 500r / min, respectively.

[0035] In step A2, the temperature and time for vacuum drying are 85℃ and 8h, respectively.

[0036] The preparation method of the pretreated PET substrate is as follows: a PET substrate with a thickness of 50 μm is placed in a 50% ethanol solution and sonicated for 2 hours, then washed with distilled water, dried at 30°C, and then treated with a 5000 eV DC discharge for 10 seconds using a plasma treatment machine to obtain the pretreated PET substrate.

[0037] Example 2

[0038] A flame-retardant PET composite label material, wherein the flame-retardant PET composite label material uses PET as a base material and an outer coating composed of inorganic fillers and aromatic Schiff base flame retardants, wherein the thickness of the outer coating on the base material is 1.5±0.05, and the inorganic filler is composed of flake mica powder and needle-shaped wollastonite powder in a mass ratio of 1:1.5, wherein the mesh ratio of the flake mica powder to the needle-shaped wollastonite powder is 1:1.3, and wherein the mesh size of the flake mica powder is 1000 mesh.

[0039] The preparation method of the flame-retardant PET composite label material includes the following steps:

[0040] (1) The inorganic filler is placed in an ethanol solution for ultrasonic treatment, and after centrifugation, the solid is dried to constant weight, which is the pretreated inorganic filler.

[0041] (2) The pretreated inorganic filler is placed in a polyvinyl alcohol solution and ultrasonically dispersed. Then, aromatic Schiff base flame retardant and leveling agent are added and stirred to form a mixed slurry. The pretreated PET substrate is immersed in the mixed slurry, taken out and dried at low temperature, and then immersed in the mixed slurry again. After being taken out and dried at low temperature, it is heated and cured. After cooling, flame-retardant PET composite label material is obtained.

[0042] In step (1), the solid-liquid ratio of the inorganic filler to the ethanol solution is 4g:75mL, wherein the mass fraction of the ethanol solution is 75%, and the power and time of the ultrasonic treatment are 650W and 4h, respectively.

[0043] In step (2), the mass ratio of the pretreated inorganic filler, polyvinyl alcohol solution, aromatic Schiff base flame retardant and leveling agent is 1.4:18:2.5:0.65. The polyvinyl alcohol solution is formed by mixing polyvinyl alcohol and distilled water at a mass ratio of 2:80 at 95°C. The soaking time is 3 minutes.

[0044] In step (2), the temperature and time for low-temperature drying are 45°C and 53 min, respectively, and the temperature and time for heating and curing are 90°C and 18 min, respectively.

[0045] The preparation method of the aromatic Schiff base flame retardant is as follows:

[0046] A1: Place anhydrous ethanol in a reaction apparatus under nitrogen gas, add 5-aminoisophthalic acid and mix to dissolve, then add bromobenzaldehyde and anhydrous acetic acid and mix and stir.

[0047] A2: After precipitation, the solid is filtered under vacuum, washed with anhydrous ethanol, and then dried under vacuum to obtain an aromatic Schiff base flame retardant.

[0048] In step A1, the mass ratio of 5-aminoisophthalic acid, anhydrous ethanol, bromobenzaldehyde, and anhydrous acetic acid is 8.2:380:8.5:7.5, and the mixing temperature, time, and speed are 88℃, 8h, and 750r / min, respectively.

[0049] In step A2, the temperature and time for vacuum drying are 85℃ and 8h, respectively.

[0050] The pretreated PET substrate is prepared as follows: a PET substrate with a thickness of 50 μm is placed in a 50% ethanol solution and sonicated for 2 hours, then washed with distilled water, dried at 30°C, and subsequently treated with a 5000 eV DC discharge for 10 seconds using a plasma treatment machine to obtain the pretreated PET substrate.

[0051] Example 3

[0052] A flame-retardant PET composite label material, wherein the flame-retardant PET composite label material uses PET as the base material and an outer coating composed of inorganic fillers and aromatic Schiff base flame retardants, wherein the thickness of the outer coating on the base material is 1.5±0.05, and the inorganic filler is composed of flake mica powder and needle-shaped wollastonite powder in a mass ratio of 1:2, wherein the mesh ratio of the flake mica powder to the needle-shaped wollastonite powder is 1:1.35, and wherein the mesh size of the flake mica powder is 1000 mesh.

[0053] The preparation method of the flame-retardant PET composite label material includes the following steps:

[0054] (1) The inorganic filler is placed in an ethanol solution for ultrasonic treatment, and after centrifugation, the solid is dried to constant weight, which is the pretreated inorganic filler.

[0055] (2) The pretreated inorganic filler is placed in a polyvinyl alcohol solution and ultrasonically dispersed. Then, aromatic Schiff base flame retardant and leveling agent are added and stirred to form a mixed slurry. The pretreated PET substrate is immersed in the mixed slurry, taken out and dried at low temperature, and then immersed in the mixed slurry again. After being taken out and dried at low temperature, it is heated and cured. After cooling, flame-retardant PET composite label material is obtained.

[0056] In step (1), the solid-liquid ratio of the inorganic filler to the ethanol solution is 5g:100mL, wherein the mass fraction of the ethanol solution is 75%, and the power and time of the ultrasonic treatment are 800W and 5h, respectively.

[0057] In step (2), the mass ratio of the pretreated inorganic filler, polyvinyl alcohol solution, aromatic Schiff base flame retardant and leveling agent is 1.8:20:3:0.8. The polyvinyl alcohol solution is formed by mixing polyvinyl alcohol and distilled water at a mass ratio of 3:80 at 95°C. The soaking time is 4 minutes.

[0058] In step (2), the temperature and time for low-temperature drying are 50°C and 60 min, respectively, and the temperature and time for heating and curing are 100°C and 20 min, respectively.

[0059] The preparation method of the aromatic Schiff base flame retardant is as follows:

[0060] A1: Place anhydrous ethanol in a reaction apparatus under nitrogen gas, add 5-aminoisophthalic acid and mix to dissolve, then add bromobenzaldehyde and anhydrous acetic acid and mix and stir.

[0061] A2: After precipitation, the solid is filtered under vacuum, washed with anhydrous ethanol, and then dried under vacuum to obtain an aromatic Schiff base flame retardant.

[0062] In step A1, the mass ratio of 5-aminoisophthalic acid, anhydrous ethanol, bromobenzaldehyde, and anhydrous acetic acid is 8-8.5:360-400:8.5:7-8, and the mixing temperature, time, and speed are 90℃, 8h, and 1000r / min, respectively.

[0063] In step A2, the vacuum drying temperature and time are 85℃ and 8.5h, respectively.

[0064] The pretreated PET substrate is prepared as follows: a PET substrate with a thickness of 50 μm is placed in a 50% ethanol solution and sonicated for 2 hours, then washed with distilled water, dried at 30°C, and subsequently treated with a 5000 eV DC discharge for 10 seconds using a plasma treatment machine to obtain the pretreated PET substrate.

[0065] Comparative Example 1

[0066] Based on Example 2, the flaky mica powder in the inorganic filler was removed and replaced with an equal mass of acicular wollastonite powder, while other conditions remained the same as in Example 2.

[0067] Comparative Example 2

[0068] Based on Example 2, the needle-shaped wollastonite powder in the inorganic filler was removed and replaced with an equal mass of flaky mica powder, while other conditions remained the same as in Example 2.

[0069] Comparative Example 3

[0070] Based on Example 2, the mesh ratio of flaky mica powder to needle-shaped wollastonite powder was adjusted to 1:5, while other conditions remained the same as in Example 2.

[0071] Comparative Example 4

[0072] Based on Example 2, the mesh ratio of flaky mica powder to needle-shaped wollastonite powder was adjusted to 1:1, while other conditions remained the same as in Example 2.

[0073] Comparative Example 5

[0074] Based on Example 2, the inorganic filler was removed and replaced with an equal mass of aromatic Schiff base flame retardant, while other conditions remained the same as in Example 2.

[0075] Comparative Example 6

[0076] Based on Example 2, the aromatic Schiff base flame retardant was removed and replaced with an equal mass of inorganic filler, while other conditions remained the same as in Example 2.

[0077] Performance testing

[0078] Surface shape and network density: The flame-retardant PET composite label materials prepared in Examples 1-3 and Comparative Examples 1-6 were cut into 3cm×3cm samples. The samples were scanned with an electron microscope to observe and count the proportion of the network. The network was ≥80% and considered very dense, 50-79% and considered dense, and ≤50% and considered not dense.

[0079] Limiting Oxygen Index (LOI) Test: The flame-retardant PET composite label materials prepared in Examples 1-3 and Comparative Examples 1-6 were cut into 125 mm × 13 mm lengths and widths and used as test samples. The limiting oxygen index (LOI) of the test samples was tested using an oxygen index analyzer according to GB / T 2406.2-2009 "Plastics - Determination of flammability by oxygen index method - Part 2: Room temperature test". The vertical burning test (UL-94) of the test samples was conducted using a vertical burning apparatus according to GB / T 2408-2008 "Plastics - Determination of flammability - Horizontal and vertical methods".

[0080] Cantilever beam notched impact strength: The flame-retardant PET composite label materials prepared in Examples 1-3 and Comparative Examples 1-6 were cut into the same size and used as samples. In addition, the cantilever beam notched impact strength of the PET substrate was tested as a control group. The cantilever beam notched impact strength of the samples was tested at room temperature using a cantilever beam impact testing machine.

[0081] Tear strength: The flame-retardant PET composite label materials prepared in Examples 1-3 and Comparative Examples 1-6 were cut to the same size and used as samples. The tear strength of the PET substrate was also tested as a control group. The tear strength of the samples was tested according to the Elmendorf method.

[0082] The test results are shown in Table 1.

[0083] Table 1 Test Results

[0084]

[0085] Analysis of the results in Table 1 shows that the surface shapes of Examples 1-3 are all irregular and very dense grids, with a limiting oxygen index of 32% and a vertical flammability rating of VTM-0. Furthermore, the cantilever beam notched impact strength and tear strength of Examples 1-3 are greater than those of Comparative Examples 1-5. In Comparative Examples 1-2, removing the flaky mica powder or needle-like wollastonite powder from the inorganic filler reduces the cantilever beam notched impact strength and tear strength. This is because a single filler cannot form a grid structure or only a small percentage of it, weakening the mechanical support. Additionally, because it cannot be embedded in the grid structure and instead appears on the surface, the double flame-retardant defense is broken, reducing the flame-retardant effect. Comparative Examples 3-4, by removing the flaky mica powder... Adjusting the mesh size ratio of powdered to needle-shaped wollastonite powder increases or decreases the proportion of mesh-like particles, resulting in a decline in flame retardancy and mechanical properties. In Comparative Example 5, no inorganic filler was added, and the flame retardant effect of the single aromatic Schiff base flame retardant dropped sharply, with mechanical properties consistent with the PET substrate. In Comparative Example 6, no aromatic Schiff base flame retardant was used, but the excessive addition of inorganic filler resulted in disordered arrangement, leading to reduced mechanical properties. Furthermore, the flame retardant effect of the single inorganic filler was significantly poor. In conclusion, adding inorganic fillers with appropriate particle size ratios not only significantly improves the notched impact strength of the cantilever beam but also increases the tear strength. Moreover, the addition or absence of aromatic Schiff base flame retardants does not affect the mechanical properties of the material.

[0086] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A flame-retardant PET composite label material, characterized in that, The flame-retardant PET composite label material uses PET as the base material, with inorganic fillers and aromatic Schiff base flame retardants forming an outer coating layer. The thickness of the outer coating layer on the base material is 1.5±0.

05. The inorganic filler is composed of flake mica powder and needle-shaped wollastonite powder in a mass ratio of 1:1-2. The mesh ratio of the flake mica powder to the needle-shaped wollastonite powder is 1:1.25-1.35, and the mesh size of the flake mica powder is 1000 mesh. The preparation method of the flame-retardant PET composite label material includes the following steps: (1) The inorganic filler is placed in an ethanol solution for ultrasonic treatment, and after centrifugation, the solid is dried to constant weight, which is the pretreated inorganic filler. (2) The pretreated inorganic filler is placed in a polyvinyl alcohol solution and ultrasonically dispersed. Then, aromatic Schiff base flame retardant and leveling agent are added and stirred to form a mixed slurry. The pretreated PET substrate is immersed in the mixed slurry, taken out and dried at low temperature, and then immersed in the mixed slurry again. After being taken out and dried at low temperature, it is heated and cured. After cooling, flame-retardant PET composite label material is obtained. In step (2), the mass ratio of the pretreated inorganic filler, polyvinyl alcohol solution, aromatic Schiff base flame retardant and leveling agent is 1-1.8:16-20:2-3:0.5-0.

8. The polyvinyl alcohol solution is formed by mixing polyvinyl alcohol and distilled water at a mass ratio of 1-3:80 at 95°C. The soaking time is 3-4 minutes.

2. The flame-retardant PET composite label material according to claim 1, characterized in that, In step (1), the solid-liquid ratio of the inorganic filler to the ethanol solution is 3-5g:50-100mL, wherein the mass fraction of the ethanol solution is 75%, and the power and time of the ultrasonic treatment are 500-800W and 3-5h, respectively.

3. The flame-retardant PET composite label material according to claim 1, characterized in that, In step (2), the temperature and time for low-temperature drying are 40-50℃ and 45-60min, respectively, and the temperature and time for heating and curing are 80-100℃ and 15-20min, respectively.

4. The flame-retardant PET composite label material according to claim 1, characterized in that, The preparation method of the aromatic Schiff base flame retardant is as follows: A1: Place anhydrous ethanol in a reaction apparatus under nitrogen gas, add 5-aminoisophthalic acid and mix to dissolve, then add bromobenzaldehyde and anhydrous acetic acid and mix and stir. A2: After precipitation, the solid is filtered under vacuum, washed with anhydrous ethanol, and then dried under vacuum to obtain an aromatic Schiff base flame retardant.

5. The flame-retardant PET composite label material according to claim 4, characterized in that, In step A1, the mass ratio of 5-aminoisophthalic acid, anhydrous ethanol, bromobenzaldehyde, and anhydrous acetic acid is 8-8.5:360-400:8.5:7-8, and the mixing temperature, time, and speed are 85-90℃, 8h, and 500-1000r / min, respectively.

6. The flame-retardant PET composite label material according to claim 4, characterized in that, In step A2, the vacuum drying temperature and time are 85℃ and 8-8.5h, respectively.

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