A coating reflective film based on organic fluorescent coating and preparation method thereof

Abstract

The present invention discloses a coated reflective film based on an organic fluorescent coating and a preparation method thereof. A new topological structure [4+4]COF (3D-TPE-COF) with tetraphenylethylene (TPE) units is prepared using tetrakis(4-aminophenyl)methane and tetrakis-(4-formyl-(1,1-biphenyl))ethylene as reaction monomers. The covalent organic framework material 3D-TPE-COF is added as a fluorescent material to a coating liquid to prepare a coated reflective film based on the organic fluorescent coating. The obtained reflective film can convert high-energy blue light, making the luminance of the backlight module higher and closer to white. At the same time, the 3D-TPE-COF fluorescent material and polymer particles can form hydrogen bonds in the coating liquid to prevent polymer particle agglomeration, thereby improving the wear and scratch resistance of the coated reflective film.

Description

Technical Field

[0001] The present invention belongs to the technical field of optical films, and in particular relates to a coating reflective film based on an organic fluorescent coating and a preparation method thereof. Background Art

[0002] There are many ways to achieve white light LEDs. One of the more commonly used methods is to use a blue light LED as a chip and apply a layer of yellow phosphor on it. When powered on, the LED chip emits blue light, part of which shines on the phosphor. After the high-energy photons of the blue light are absorbed by the phosphor, the electrons jump to a high-energy state and then emit lower-energy yellow light when returning to a low-energy state. This yellow light and the other part of the blue light can be mixed into white light.

[0003] However, due to the limited efficiency of yellow phosphor and the uneven coating process, some high-energy blue light may leak out, causing blue light overflow. This leaked blue light, due to its relatively high energy, can cause significant damage to the eyes. Long-term use of LEDs containing high-intensity blue light may cause vision loss and retinal damage.

[0004] In response to this situation, anti-blue light protective films came into being. For example, invention patent CN103935097B discloses "Anti-blue light hardened film". The anti-blue light hardened film includes a base film, one side of which is sequentially provided with an anti-ultraviolet coating and an anti-blue light hardened coating. The anti-blue light hardened film has a simple structure, high hardness, good adhesion, high transparency, and can absorb blue light, which is beneficial to the user's eye protection. It can also absorb more than 99% of ultraviolet rays, which can slow down the aging of the user's skin and is widely used in the field of 3C product screen protective films. However, the anti-blue light protective film requires the preparation of an additional film, and the purpose of blue light protection is achieved through multiple processes such as preparing the substrate, adding a blue light absorber, coating, laminating the protective film, and winding. The entire process is cumbersome, and the process and raw material costs are relatively high, especially for the poor conversion effect of high-energy blue light. Summary of the Invention

[0005] The present invention aims to address the above-mentioned problems existing in the prior art and proposes a coated reflective film based on an organic fluorescent coating and a preparation method thereof. A 3D-TPE-COF fluorescent material is prepared using tetrakis(4-aminophenyl)methane (TAPM) and tetrakis-(4-formyl-(1,1-biphenyl))ethylene (TPE-Ph-CHO) as reaction monomers. This 3D-TPE-COF fluorescent material is then added to a coating liquid to prepare a coated reflective film based on the organic fluorescent coating. The resulting reflective film can convert high-energy blue light, making the backlight module emit a brighter and closer to white light. At the same time, the 3D-TPE-COF fluorescent material and the polymer in the coating liquid can form hydrogen bonds to prevent polymer particles from agglomerating, thereby improving the wear and scratch resistance of the coated reflective film.

[0006] The purpose of the present invention is achieved through the following technical solutions:

[0007] On the one hand, a coated reflective film based on an organic fluorescent coating includes a substrate and an organic fluorescent coating. The organic fluorescent coating is formed by thermally curing a coating liquid. The coating liquid includes a 3D-TPE-COF fluorescent material. The 3D-TPE-COF fluorescent material is a covalent organic framework material prepared using tetrakis(4-aminophenyl)methane (TAPM) and tetrakis-(4-formyl-(1,1-biphenyl))ethylene (TPE-Ph-CHO) as reactive monomers. Its structural formula is shown below:

[0008]

[0009] Furthermore, the 3D-TPE-COF fluorescent material is obtained by solvent thermal synthesis using tetrakis(4-aminophenyl)methane (TAPM) and tetrakis-(4-formyl-(1,1-biphenyl))ethylene (TPE-Ph-CHO) as monomers, o-dichlorobenzene and mesitylene as reaction solvents, under the action of a catalyst. The corresponding synthesis equation is shown in the attached figure. Figure 3 shown.

[0010] The molar ratio of TAPM to TPE-Ph-CHO is 1:1.

[0011] The catalyst comprises at least one of acetic acid, sulfuric acid, and trifluoromethanesulfonic acid, preferably acetic acid.

[0012] Furthermore, the 3D-TPE-COF fluorescent material has the characteristics of yellow organic phosphor and can convert high-energy blue light, making the backlight module emit light with higher brightness and closer to white.

[0013] Furthermore, the coating liquid includes 3D-TPE-COF fluorescent material, polymer particles, adhesive, curing agent, antistatic agent, hydrogen bond network dispersion solvent, and coating liquid dispersion solvent.

[0014] Preferably, the mass ratio of the polymer particles to the 3D-TPE-COF fluorescent material is 3:1 to 11:1;

[0015] Preferably, the mass of the 3D-TPE-COF fluorescent material accounts for 0.3 to 0.9 wt % of the total mass of the coating liquid;

[0016] Furthermore, the coating solution comprises, by mass, the following components:

[0017] 3D-TPE-COF fluorescent material: 0.3-0.9 wt%

[0018] Polymer particles: 2.7-3.3 wt%

[0019] Adhesive: 34-36 wt%

[0020] Curing agent: 3-4 wt%

[0021] Antistatic agent: 0.1~0.3 wt%

[0022] Hydrogen bond network dispersing solvent: 24-26 wt%

[0023] The balance is the coating liquid dispersion solvent.

[0024] The polymer particles include at least one of polyethylene terephthalate (PET), polymethyl methacrylate (PMMA), polybutyl methacrylate (PBMA), polyamide (PA), and polyurethane (PU), preferably polyethylene terephthalate (PET).

[0025] The hydrogen bond network dispersing solvent includes at least one of carbon tetrachloride and tetrahydrofuran, so that the 3D-TPE-COF fluorescent material and the polymer particles are pre-dispersed in the solvent to form a hydrogen bond network;

[0026] The adhesive comprises at least one of acrylic resin adhesive, polycarbonate resin adhesive, polyurethane resin adhesive, and polyimide resin adhesive, preferably acrylic resin adhesive;

[0027] The curing agent includes at least one of isocyanate, epoxy resin, methylphenolic resin, and dicyandiamide, preferably an isocyanate curing agent;

[0028] The antistatic agent includes at least one of lithium bis(trifluoromethylsulfonyl)imide and lithium trifluoromethanesulfonate.

[0029] The coating liquid dispersion solvent includes at least one of N,N-dimethylformamide, ethyl acetate, and butyl acetate;

[0030] The 3D-TPE-COF fluorescent material and polymer particles are pre-dispersed in a hydrogen bond network dispersing solvent to obtain a first suspension;

[0031] The first suspension, adhesive, curing agent and antistatic agent are dispersed in a coating liquid dispersing solvent to prepare a coating liquid.

[0032] The substrate includes at least one of PET polyester film and polypropylene film;

[0033] Preferably, the substrate is PET polyester film.

[0034] The thickness of the organic fluorescent coating is 5 to 20 μm.

[0035] On the other hand, a method for preparing a coated reflective film based on an organic fluorescent coating includes synthesizing a 3D-TPE-COF fluorescent material and preparing the coated reflective film:

[0036] Step 1: Synthesis of 3D-TPE-COF fluorescent material. The specific preparation steps are as follows:

[0037] (1) Tetrakis(4-aminophenyl)methane (TAPM) monomer and tetrakis(4-formyl-(1,1-biphenyl))ethylene (TPE-Ph-CHO) monomer were dispersed in a mixed solvent of o-dichlorobenzene and mesitylene and ultrasonically treated for 20–40 min to obtain a monomer solution;

[0038] The amount of tetrakis(4-aminophenyl)methane and tetrakis-(4-formyl-(1,1-biphenyl))ethylene is 1:1 in molar ratio;

[0039] The mixed solvent of o-dichlorobenzene and mesitylene is in a volume ratio of o-dichlorobenzene to mesitylene of 1:1;

[0040] The concentration of the tetrakis(4-aminophenyl)methane monomer solution and the tetrakis-(4-formyl-(1,1-biphenyl))ethylene monomer solution are calculated based on the amount of substance, i.e., the amount of tetrakis(4-aminophenyl)methane monomer or tetrakis-(4-formyl-(1,1-biphenyl))ethylene monomer substance: the volume of the mixed solvent, both of which are n 单体 / V 混合溶剂 =67 / 400 (mol / L);

[0041] (2) The monomer solution was placed in a polytetrafluoroethylene-lined stainless steel reactor, and the catalyst aqueous solution was slowly added dropwise. The apparatus was degassed and vacuum-sealed, and the reaction was carried out at 120°C for 5 to 9 days.

[0042] The concentration of the catalyst aqueous solution is 5 to 7 mol / L;

[0043] In terms of molar ratio, the total amount of the monomer is 3 to 4 times the amount of the catalyst;

[0044] The catalyst comprises at least one of acetic acid, sulfuric acid, and trifluoromethanesulfonic acid, preferably acetic acid;

[0045] (3) After the reaction is completed, the apparatus is cooled to room temperature, the resulting precipitate is filtered out, and the product is washed alternately with tetrahydrofuran, acetone, and dichloromethane;

[0046] (4) Drying: vacuum drying at 75-85°C for 10-14 hours to obtain a powdery product, namely the 3D-TPE-COF fluorescent material.

[0047] Step 2: Preparation of a reflective film based on an organic fluorescent coating, specifically the following steps:

[0048] (1) According to the formula, the 3D-TPE-COF fluorescent material and polymer particles prepared in step 1 are dispersed in a hydrogen bond network dispersing solvent, ultrasonically dispersed for 1 hour, and stirred to obtain a first suspension;

[0049] The polymer particles include at least one of polyethylene terephthalate (PET), polymethyl methacrylate (PMMA), polybutyl methacrylate (PBMA), polyamide (PA), and polyurethane (PU), preferably polyethylene terephthalate (PET);

[0050] The hydrogen bond network dispersing solvent includes at least one of carbon tetrachloride and tetrahydrofuran;

[0051] (2) Dispersing the first suspension obtained in step (1) and the adhesive, curing agent, and antistatic agent into the coating liquid dispersing solvent in sequence according to the formula, and stirring evenly to obtain the final coating liquid;

[0052] The adhesive comprises at least one of acrylic resin adhesive, polycarbonate resin adhesive, polyurethane resin adhesive, and polyimide resin adhesive, preferably acrylic resin adhesive;

[0053] The curing agent includes at least one of isocyanate, epoxy resin, methylphenolic resin, and dicyandiamide, preferably an isocyanate curing agent;

[0054] The antistatic agent includes at least one of lithium bis(trifluoromethylsulfonyl)imide and lithium trifluoromethanesulfonate; the coating liquid dispersion solvent includes at least one of N,N-dimethylformamide, ethyl acetate and butyl acetate;

[0055] (3) coating the obtained coating liquid on the surface of the substrate, and curing it by heating in an oven to obtain a coating reflective film based on the organic fluorescent coating;

[0056] The substrate includes at least one of PET polyester film and polypropylene film;

[0057] The thermal curing temperature of the coating is 100-120° C., and the reaction time is 1-3 minutes.

[0058] The above-mentioned reflective film based on an organic fluorescent coating can be applied to a display module / display device; the display module includes at least one of an LCD module and a Mini-LED module;

[0059] The display device includes at least one of a television, a mobile phone, a laptop computer, and a vehicle-mounted central control screen.

[0060] Compared with the prior art, the present invention has the following beneficial effects:

[0061] (1) The reaction monomer TPE-Ph-CHO carries a tetraphenylethylene (TPE) unit, which makes the material have the characteristics of AIE (aggregation-induced emission, AIE) aggregation-induced emission material; the TPE unit aggregates in the three-dimensional COF framework, so that 3D-TPE-COF can emit yellow light with a maximum emission wavelength of 543nm and a high fluorescence quantum yield; when the concentration of 3D-TPE-COF is higher, the material emits stronger light and has a higher sensitivity; 3D-TPE-COF also has strong stability to ultraviolet excitation light and will not be photobleached; in addition, the reaction monomers have 4 reaction sites, which makes TPE aggregate more and the material more fluorescent; the biphenyl and imine bonds are conjugated structures, which also enhances fluorescence; therefore, the present invention places the 3D-TPE-COF fluorescent material in a coating liquid to prepare an organic fluorescent coating, which is used to convert the high-energy blue light leaked from the LED lamp, so that the brightness of the backlight module is higher and closer to white;

[0062] (2) 3D-TPE-COF fluorescent material is a new topological structure [4+4] COF with multiple interpenetrating point topology. Multiple interpenetrating networks are interwoven to form a three-dimensional support framework, which effectively disperses external stress and prevents the collapse of a single network. This structure significantly improves the thermal stability and mechanical strength of the material, especially under high temperature or high pressure environments. Therefore, 3D-TPE-COF is resistant to organic chemical solvents during the liquid preparation process and resistant to high temperatures during the thermal curing process.

[0063] (3) 3D-TPE-COF fluorescent materials are formed by the Schiff base reaction of aldehyde compounds and primary amines. Their structure contains carbon-nitrogen double bonds and incompletely reacted amino groups. The presence of hydrogen elements on the surface of polymer particles creates a tendency for intermolecular interactions such as hydrogen bonds to form between the two. Therefore, the 3D-TPE-COF fluorescent material can form a hydrogen bond network with the polymer particles, preventing the polymer particles from agglomerating and improving the wear and scratch resistance of the coated reflective film. BRIEF DESCRIPTION OF THE DRAWINGS

[0064] Figure 1 A schematic structural diagram of a coated reflective film based on an organic fluorescent coating.

[0065] 1—polymer particles; 2—3D-TPE-COF fluorescent material; 3—organic fluorescent coating; 4—substrate.

[0066] Figure 2 Steady-state fluorescence spectrum of 3D-TPE-COF fluorescent material (λ ex =450nm).

[0067] Figure 3Synthesis equation of 3D-TPE-COF fluorescent material. DETAILED DESCRIPTION

[0068] The following are specific embodiments of the present invention, which further describe the technical solutions of the present invention.

[0069] Unless otherwise specified, the materials used in the present invention are conventional commercial products, and the methods used are conventional technical means.

[0070] Tetrakis(4-aminophenyl)methane (TAPM): analytical grade, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0071] Tetrakis-(4-formyl-(1,1-biphenyl))ethylene (TPE-Ph-CHO): analytical grade, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0072] YAG:Ce³⁺ fluorescent material: purchased from Jinhong Crystal Materials (Shanghai) Co., Ltd.

[0073] Example 1

[0074] A coating reflective film based on an organic fluorescent coating, the structural diagram of which is shown in the attached figure. Figure 1 As shown, it includes a substrate and an organic fluorescent coating. The organic fluorescent coating is formed by thermally curing a coating liquid. The coating liquid includes a 3D-TPE-COF fluorescent material. The 3D-TPE-COF fluorescent material is a covalent organic framework material. When added to the coating liquid, the resulting coated reflective film can convert high-energy blue light, thereby making the backlight module emit a higher brightness and closer to white. At the same time, the 3D-TPE-COF fluorescent material and polymer particles can form hydrogen bonds in the coating liquid to prevent polymer particles from agglomerating, thereby improving the wear and scratch resistance of the coated reflective film. The specific preparation steps of the coated reflective film based on the organic fluorescent coating are as follows:

[0075] Step 1: Preparation of 3D-TPE-COF fluorescent material. The corresponding synthesis formula is as shown in the attached Figure 3 As shown, the specific preparation steps are as follows:

[0076] (1) Disperse 2.55 g of tetrakis(4-aminophenyl)methane (TAPM) monomer and 5 g of tetrakis(4-formyl-(1,1-biphenyl))ethylene (TPE-Ph-CHO) monomer in a mixed solvent of 20 mL of o-dichlorobenzene and 20 mL of mesitylene and ultrasonicate for 30 min to obtain a monomer solution.

[0077] (2) The monomer solution was placed in a polytetrafluoroethylene-lined stainless steel reactor, and 6 ml of acetic acid aqueous solution (6 mol / L) was slowly added dropwise. The apparatus was degassed and vacuum-sealed, and the reaction was carried out at 120°C for 7 days.

[0078] (3) After the reaction is completed, the apparatus is cooled to room temperature, the resulting precipitate is filtered out, and the product is washed alternately with tetrahydrofuran, acetone, and dichloromethane;

[0079] (4) Dry under vacuum at 80 °C for 12 h to obtain a powdered product 3D-TPE-COF fluorescent material. The steady-state fluorescence spectrum of 3D-TPE-COF was measured using a fluorescence spectrometer FL3-111 (see attached Figure 2 shown).

[0080] Step 2: Preparation of a reflective film based on an organic fluorescent coating, specifically the following steps:

[0081] (1) Dispersing 0.5 parts of 3D-TPE-COF fluorescent material and 3.1 parts of polyethylene terephthalate polymer particles in 25 parts of carbon tetrachloride, ultrasonically dispersing for 1 hour, and stirring to obtain a first suspension;

[0082] (2) 35 parts of acrylic resin adhesive, 3.5 parts of isocyanate curing agent, 0.2 parts of lithium bis(trifluoromethylsulfonyl)imide) and the first suspension were dispersed in 32.7 parts of ethyl acetate in sequence, and stirred to obtain the final coating solution;

[0083] (3) The obtained coating liquid was coated on the surface of the PET reflective substrate, and heated in an oven at 110° C. for 2 minutes to form an organic fluorescent coating. The thickness of the organic fluorescent coating was 10 μm.

[0084] Example 2

[0085] As provided in Example 1, a coated reflective film based on an organic fluorescent coating is prepared, wherein the synthesis reaction time of the 3D-TPE-COF fluorescent material in step 1 is 5 days, and the remaining steps remain unchanged.

[0086] Example 3

[0087] As provided in Example 1, a coated reflective film based on an organic fluorescent coating is prepared, wherein the synthesis reaction time of the 3D-TPE-COF fluorescent material in step 1 is 9 days, and the remaining steps remain unchanged.

[0088] Example 4

[0089] As provided in Example 1, a coated reflective film based on an organic fluorescent coating is provided, wherein the catalyst for synthesizing the fluorescent material of 3D-TPE-COF in step 1 is trifluoromethanesulfonic acid, and the remaining steps remain unchanged.

[0090] Example 5

[0091] As provided in Example 1, a coated reflective film based on an organic fluorescent coating is prepared, wherein the polymer particles are PMMA and the remaining steps remain unchanged.

[0092] Example 6

[0093] A coated reflective film based on an organic fluorescent coating is provided in Example 1, wherein in step 2, the 3D-TPE-COF fluorescent material is 0.3 parts, the polyethylene terephthalate polymer particles are 3.3 parts, and the mass ratio of the polyethylene terephthalate polymer particles to the 3D-TPE-COF fluorescent material is 11:1.

[0094] Example 7

[0095] A coated reflective film based on an organic fluorescent coating is provided in Example 1, wherein in step 2, the 3D-TPE-COF fluorescent material is 0.9 parts, the polyethylene terephthalate polymer particles are 2.7 parts, and the mass ratio of the polyethylene terephthalate polymer particles to the 3D-TPE-COF fluorescent material is 3:1.

[0096] Comparative Example 1

[0097] As provided in Example 1, a coated reflective film based on an organic fluorescent coating is provided. In the reflective film of Comparative Example 1, no 3D-TPE-COF fluorescent material is added.

[0098] Comparative Example 2

[0099] As provided in Example 1, a coated reflective film based on an organic fluorescent coating is provided, wherein the fluorescent material in step 2 is a commercially available YAG:Ce³⁺ fluorescent material.

[0100] Comparative Example 3

[0101] As provided in Example 1, a coated reflective film based on an organic fluorescent coating is provided, wherein the 3D-TPE-COF fluorescent material in step 2 is 1.2 parts, and the mass ratio of the 3D-TPE-COF fluorescent material in the coating solution is 1.2 wt %, which is higher than the preferred range of 0.3-0.9 wt %.

[0102] Comparative Example 4

[0103] As provided in Example 1, a coated reflective film based on an organic fluorescent coating is provided, wherein the 3D-TPE-COF fluorescent material in step 2 is 0.1 parts, and the mass ratio of the 3D-TPE-COF fluorescent material in the coating solution is 0.1 wt %, which is lower than the preferred range of 0.3-0.9 wt %.

[0104] Comparative Example 5

[0105] For a reflective film based on an organic fluorescent coating as provided in Example 1, the tetrakis(4-aminophenyl)methane monomer in step 1 is adjusted to tris(4-aminophenyl)methane, and the remaining steps remain unchanged.

[0106] Comparative Example 6

[0107] For a reflective film based on an organic fluorescent coating as provided in Example 1, the tetrakis-(4-formyl-(1,1-biphenyl))ethylene monomer in step 1 is adjusted to tetrakis-(4-formylphenyl)ethylene, and the remaining steps remain unchanged.

[0108] Comparative Example 7

[0109] For a coated reflective film based on an organic fluorescent coating as provided in Example 1, the tetrakis(4-aminophenyl)methane monomer in step 1 is adjusted to tris(4-aminophenyl)methane, and the tetrakis-(4-formyl-(1,1-biphenyl))ethylene monomer is adjusted to tetrakis-(4-formylphenyl)ethylene, while the remaining steps remain unchanged.

[0110] The performance of the organic fluorescent coating-based reflective films prepared in the above examples and comparative examples was evaluated according to the following method:

[0111] (1) Luminance, CIE color coordinates test: Place the coated reflective film in a direct-lit quantum dot backlight module and use a luminance meter BM-7A to test the brightness and color coordinates; luminance represents the luminous effect, and CIE color coordinates represent the luminous color;

[0112] (2) Scratch test: Take a 20*20 mm reflective film and stick it on the sample table of a steel wool friction resistance tester. With a 200 g weight, rub the coating surface of the reflective film back and forth against the light guide plate. Repeat 50 cycles at a speed of 12 mm / s. Then use a USB digital microscope to observe and compare the light guide plate area before and after friction. No obvious scratches are excellent, 1-5 lines of scratches are good, 6-15 lines of scratches are medium, and more than 15 lines of scratches are poor.

[0113] The performance characterization results of each embodiment and comparative example are shown in Table 1.

[0114] Table 1 Performance characterization results of Examples 1 to 7 and Comparative Examples 1 to 7

[0115]

[0116] The results of Example 1 and Comparative Examples 1 and 2 show that the addition of a 3D-TPE-COF fluorescent material, which exhibits yellow organic phosphor properties, to a reflective film coating can reduce the film's blue light transmittance and improve its brightness. The resulting backlight module exhibits CIE color coordinates of (0.3291, 0.3309), close to the standard pure white light coordinates of (0.33, 0.33). Even after 1000 hours of illumination, the reflective film's blue light transmittance remains low, demonstrating good stability. Furthermore, the 3D-TPE-COF fluorescent material and polyethylene terephthalate polymer particles form a hydrogen bond network, improving the wear and scratch resistance of the coated reflective film. Commercial YAG:Ce³⁺ rare earth phosphors also exhibit similar optical effects, but their overall blue light conversion performance is inferior to that of 3D-TPE-COF fluorescent materials. Furthermore, this material is relatively hard and has poor processing properties. Its addition to the coating can result in poor scratch resistance, making the coated reflective film susceptible to scratches on the light guide plate.

[0117] The results of Examples 1, 2, and 3 demonstrate that the synthesis time of the 3D-TPE-COF fluorescent material is also critical. Short synthesis times result in substandard optical performance. Longer synthesis times meet the optical performance standards, but the material is too large and difficult to disperse, resulting in a poor hydrogen bond network between the 3D-TPE-COF fluorescent material and the polymer particles.

[0118] The results of Examples 1 and 4 show that using a strong acid such as trifluoromethanesulfonic acid as a catalyst for synthesizing 3D-TPE-COF fluorescent materials will result in a poor blue light conversion effect of the coated reflective film based on the organic fluorescent coating, and the color coordinates will deviate from the standard pure white light.

[0119] The results of Examples 1 and 5 show that the terminal groups of the polyethylene terephthalate polymer particles include carboxyl and hydroxyl groups, which can form a hydrogen bond network with the 3D-TPE-COF fluorescent material to prevent polymer particles from agglomerating, thereby improving the wear and scratch resistance of the coated reflective film.

[0120] The results of Examples 1, 6, and 7 show that the mass ratio of polyethylene terephthalate polymer particles to 3D-TPE-COF fluorescent material is too high, the hydrogen bonding network effect between the two is average, and the scratch resistance of the coated reflective film is not significantly improved. The amount of 3D-TPE-COF fluorescent material added is too little, the blue light transmittance of the reflective film is high, and the overall brightness of the backlight module is low. The mass ratio of polyethylene terephthalate polymer particles to 3D-TPE-COF fluorescent material is too low, and the amount of 3D-TPE-COF fluorescent material added is too high, resulting in the color coordinates of the backlight module being yellowish, the picture being yellowish, and the overall brightness being reduced.

[0121] The results of Example 1, Comparative Examples 3, and Comparative Examples 4 show that when too much 3D-TPE-COF fluorescent material is added, the color coordinates of the backlight module are severely yellowish, and the overall brightness is reduced. When too little 3D-TPE-COF fluorescent material is added, the optical effect and hydrogen bonding effect of the fluorescent material are not obvious.

[0122] Example 1 and Comparative Examples 5-7 examined the optical properties of COFs prepared using organic monomers with varying structural characteristics after application as reflective films. The choice of reactive monomers is crucial. The aldehyde and amine reactive monomers in the 3D-TPE-COF fluorescent material of this invention each possess four reactive sites, resulting in greater TPE aggregation and a more fluorescent product. The aldehyde monomers contain a biphenyl structure, which remains after reaction. Consequently, the biphenyl and imine bonds in the product form a conjugated structure, enhancing the material's fluorescence.

Claims

1. A reflective film based on an organic fluorescent coating, comprising a substrate and an organic fluorescent coating, wherein the organic fluorescent coating is formed by thermally curing a coating liquid, characterized in that: The coating solution includes a 3D-TPE-COF fluorescent material and polymer particles. The 3D-TPE-COF fluorescent material is a covalent organic framework material, and its chemical structure is as follows: The polymer particles include at least one of polyethylene terephthalate, polymethyl methacrylate, polybutyl methacrylate, polyamide, and polyurethane; The mass ratio of the polymer particles to the 3D-TPE-COF fluorescent material is 3:1 to 11:1; The mass of the 3D-TPE-COF fluorescent material accounts for 0.3 to 0.9 wt % of the total mass of the coating liquid.

2. The reflective film based on an organic fluorescent coating according to claim 1, characterized in that: The 3D-TPE-COF fluorescent material is prepared by a solvent thermal synthesis method using tetrakis(4-aminophenyl)methane and tetrakis-(4-formyl-(1,1-biphenyl))ethylene as reaction monomers, o-dichlorobenzene and mesitylene as reaction solvents, under the action of a catalyst; the tetrakis(4-aminophenyl)methane and tetrakis-(4-formyl-(1,1-biphenyl))ethylene monomers are used in a molar ratio of 1:1; and the catalyst includes at least one of acetic acid, sulfuric acid, and trifluoromethanesulfonic acid.

3. The reflective film based on an organic fluorescent coating according to claim 2, characterized in that: The coating liquid further comprises an adhesive, a curing agent, an antistatic agent, a hydrogen bond network dispersing solvent, and a coating liquid dispersing solvent.

4. The reflective film based on an organic fluorescent coating according to claim 3, characterized in that: The components of the coating liquid include, by mass, 0.3-0.9 wt% of 3D-TPE-COF fluorescent material, 2.7-3.3 wt% of polymer particles, 34-36 wt% of adhesive, 3-4 wt% of curing agent, 0.1-0.3 wt% of antistatic agent, 24-26 wt% of hydrogen bond network dispersion solvent, and the remainder being the coating liquid dispersion solvent.

5. The reflective film based on an organic fluorescent coating according to claim 4, characterized in that: The hydrogen bond network dispersion solvent includes at least one of carbon tetrachloride and tetrahydrofuran; the adhesive includes at least one of acrylic resin adhesive, polycarbonate resin adhesive, polyurethane resin adhesive, and polyimide resin adhesive; the curing agent includes at least one of isocyanate, epoxy resin, methylphenolic resin, and dicyandiamide; the antistatic agent includes at least one of lithium bis(trifluoromethylsulfonyl)imide and lithium trifluoromethanesulfonate; and the coating liquid dispersion solvent includes at least one of N,N-dimethylformamide, ethyl acetate, and butyl acetate.

6. The reflective film based on an organic fluorescent coating according to claim 5, characterized in that: The substrate includes at least one of a PET polyester film and a polypropylene film; the thickness of the organic fluorescent coating is 5 to 20 μm.

7. The method for preparing a reflective film based on an organic fluorescent coating according to any one of claims 1 to 6, characterized in that: The steps for preparing the coated reflective film are as follows: (1) dispersing the 3D-TPE-COF fluorescent material and polymer particles into a hydrogen bond network dispersing solvent according to the formula to obtain a first suspension; (2) dispersing the first suspension obtained in step (1) as well as the adhesive, curing agent, and antistatic agent into the coating liquid dispersing solvent in sequence according to the formula to obtain the final coating liquid; (3) The obtained coating liquid is coated on the surface of the reflective substrate and cured by heating in an oven to obtain a coated reflective film based on the organic fluorescent coating.

8. The method for preparing a reflective film based on an organic fluorescent coating according to claim 7, characterized in that: The preparation steps of the 3D-TPE-COF fluorescent material are as follows: tetrakis(4-aminophenyl)methane monomer and tetrakis-(4-formyl-(1,1-biphenyl))ethylene monomer are dispersed in a mixed solvent of o-dichlorobenzene and mesitylene, a catalyst aqueous solution is added dropwise, and the mixture is reacted at 120° C. for 5 to 9 days; after the reaction is completed, the obtained precipitate is washed and dried to obtain the 3D-TPE-COF fluorescent material; the mixed solvent of o-dichlorobenzene and mesitylene is calculated in a volume ratio of o-dichlorobenzene to mesitylene of 1:1; the concentrations of the tetrakis(4-aminophenyl)methane monomer solution and the tetrakis-(4-formyl-(1,1-biphenyl))ethylene monomer solution are calculated in terms of molar concentration, i.e., amount of substance: volume of the mixed solvent, and are both n 单体 / V 混合溶剂 =67mol / 400L; the concentration of the catalyst aqueous solution is 5-7mol / L; in terms of molar ratio, the total amount of the monomer is 3-4 times the amount of the catalyst.

9. The method for preparing a reflective film based on an organic fluorescent coating according to claim 8, characterized in that: The temperature of the heating and curing in the step (3) is 100-120° C., and the reaction time is 1-3 minutes.

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