Coating reflecting film based on organic fluorescent coating and preparation method thereof

Abstract

The invention discloses a coated reflecting film based on an organic fluorescent coating and a preparation method of the coated reflecting film, tetra (4-aminophenyl) methane and tetra-(4-formyl-(1, 1-biphenyl)) ethylene are used as reaction monomers to prepare a novel topological structure [4 + 4] COF (3D-TPE-COF) with a tetraphenylethylene (TPE) unit, and the novel topological structure [4 + 4] COF (3D-TPE-COF) is used for preparing the reflective film based on the organic fluorescent coating. The covalent organic framework material 3D-TPE-COF is added into coating liquid as a fluorescent material to prepare a coating reflecting film based on an organic fluorescent coating, and the obtained reflecting film can convert high-energy blue light, so that the brightness of light emitted by a backlight module is higher and closer to white; meanwhile, the 3D-TPE-COF fluorescent material and the polymer particles can form hydrogen bonds in the coating liquid to avoid aggregation of the polymer particles, so that the wear resistance and scratch resistance of the coating reflecting film are improved.

Description

Technical Field

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

[0002] There are various ways to achieve white light LEDs. Currently, a relatively common method is: using a blue LED as the chip, applying a layer of yellow phosphor on it. After power-on, the LED chip emits blue light. When a part of the blue light irradiates onto the phosphor, the high-energy photons of the blue light are absorbed by the phosphor. After the electrons jump to the high-energy state and then return to the low-energy state, yellow light with lower energy is emitted. This yellow light can be mixed with another part of the blue light to form white light.

[0003] However, due to the limited efficiency of the yellow phosphor and the uneven coating process, some high-energy blue light may leak out, resulting in the phenomenon of blue light spillover. Since these leaked blue lights have relatively high energy, they can cause greater harm to the eyes. Long-term use of LEDs containing high-intensity blue light may lead to vision decline and retinal damage.

[0004] In response to this situation, anti-blue light protective films have emerged. For example, the invention patent CN103935097B discloses "An anti-blue light hardening film". This anti-blue light hardening film includes a base film, and an anti-ultraviolet coating and an anti-blue light hardening coating are sequentially arranged on one side of the base film; this anti-blue light hardening film has a simple structure, high hardness, good adhesion, high transparency, can absorb blue light, is beneficial to the protection of the user's eyes, and can absorb more than 99% of ultraviolet rays, and can slow down the aging of the user's skin. It is widely used in the field of 3C product screen protective films. However, the anti-blue light protective film needs to be prepared with an additional film. Through multiple processes such as preparing the base material, adding a blue light absorber, coating, laminating the protective film, and winding, the purpose of anti-blue light is achieved. The entire process flow is cumbersome, and the process and raw material costs are relatively high, especially the conversion effect on high-energy blue light is not good. Summary of the Invention

[0005] The object of the present invention is to address the above problems existing in the prior art, and propose a coated reflective film based on an organic fluorescent coating and a preparation method thereof. Using tetra(4-aminophenyl)methane (TAPM) and tetra-(4-aldehyde-(1,1-biphenyl))ethylene (TPE-Ph-CHO) as reaction monomers to prepare 3D-TPE-COF fluorescent materials, and adding them to the coating solution to prepare a coated reflective film based on an organic fluorescent coating. The obtained reflective film can convert high-energy blue light, making the brightness of the backlight module higher and closer to white; at the same time, the 3D-TPE-COF fluorescent material and the polymer can form hydrogen bonds in the coating solution to avoid the aggregation of polymer particles, improving the wear and scratch resistance of the coated reflective film.

[0006] The object of the present invention is achieved by the following technical solutions: On the one hand, a coated reflective film based on an organic fluorescent coating, comprising a substrate and an organic fluorescent coating, the organic fluorescent coating being formed by thermally curing a coating solution, the coating solution comprising a 3D-TPE-COF fluorescent material, the 3D-TPE-COF fluorescent material being a covalent organic framework material, which is prepared using tetra(4-aminophenyl)methane (TAPM) and tetra-(4-formyl-(1,1-biphenyl))ethylene (TPE-Ph-CHO) as reaction monomers, and its structural formula is shown as follows:

[0007] Further, the 3D-TPE-COF fluorescent material is obtained by solvothermal synthesis using tetra(4-aminophenyl)methane (TAPM) and tetra-(4-formyl-(1,1-biphenyl))ethylene (TPE-Ph-CHO) as monomers, ortho-dichlorobenzene and mesitylene as reaction solvents, and under the action of a catalyst. The corresponding synthesis equation is as shown in the appendix Figure 3 as follows.

[0008] The molar ratio of TAPM to TPE-Ph-CHO is 1:1.

[0009] The catalyst includes at least one of acetic acid, sulfuric acid, and trifluoromethanesulfonic acid, preferably acetic acid.

[0010] Further, the 3D-TPE-COF fluorescent material has the characteristics of a yellow organic fluorescent powder and can convert high-energy blue light, making the brightness of the backlight module higher and closer to white.

[0011] Further, the coating solution includes a 3D-TPE-COF fluorescent material, polymer particles, an adhesive, a curing agent, an antistatic agent, a hydrogen bond network dispersion solvent, and a coating solution dispersion solvent.

[0012] Preferably, the mass ratio of the polymer particles to the 3D-TPE-COF fluorescent material is 3:1 to 11:1; 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 solution; Further, by mass parts, the components of the coating solution include: 3D-TPE-COF fluorescent material: 0.3 - 0.9 wt% Polymer particles: 2.7 - 3.3 wt% Adhesive: 34 - 36 wt% Curing agent: 3 - 4 wt% Antistatic agent: 0.1 - 0.3 wt% Hydrogen bond network dispersing solvent: 24 - 26 wt% The balance is the coating liquid dispersing solvent.

[0013] 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).

[0014] The hydrogen bond network dispersing solvent includes at least one of carbon tetrachloride and tetrahydrofuran. In order to pre-disperse the 3D-TPE-COF fluorescent material and the polymer particles in the solvent to form a hydrogen bond network; The adhesive includes at least one of acrylic resin adhesives, polycarbonate resin adhesives, polyurethane resin adhesives, and polyimide resin adhesives, preferably acrylic resin adhesives; The curing agent includes at least one of isocyanates, epoxy resins, methyl phenolic resins, and dicyandiamide, preferably isocyanate curing agents; The antistatic agent includes at least one of lithium bis(trifluoromethanesulfonyl)imide and lithium trifluoromethanesulfonate.

[0015] The coating liquid dispersing solvent includes at least one of N,N-dimethylformamide, ethyl acetate, and butyl acetate; The 3D-TPE-COF fluorescent material and the polymer particles are pre-dispersed in the hydrogen bond network dispersing solvent to obtain a first suspension; The first suspension, the adhesive, the curing agent, and the antistatic agent are dispersed in the coating liquid dispersing solvent to prepare a coating liquid.

[0016] The substrate includes at least one of PET polyester film and polypropylene film; Preferably, the substrate is PET polyester film.

[0017] The thickness of the organic fluorescent coating is 5 - 20 μm.

[0018] On the other hand, a preparation method of a coated reflective film based on an organic fluorescent coating includes the synthesis of a 3D-TPE-COF fluorescent material and the preparation of a coated reflective film: Step 1, synthesis of the 3D-TPE-COF fluorescent material, and the specific preparation steps are as follows: (1) Disperse tetrakis(4-aminophenyl)methane (TAPM) monomer and tetra-(4-formyl-(1,1-biphenyl))ethylene (TPE-Ph-CHO) monomer in a mixed solvent of o-dichlorobenzene and mesitylene, and ultrasonically treat for 20 - 40 minutes to obtain a monomer solution; The usage amounts of the tetrakis(4-aminophenyl)methane and tetrakis(4-formyl-(1,1-biphenyl))ethylene, based on the molar ratio, are 1:1; For the mixed solvent of o-dichlorobenzene and mesitylene, based on the volume ratio, o-dichlorobenzene:mesitylene = 1:1; The concentrations of the tetrakis(4-aminophenyl)methane monomer solution and the tetrakis(4-formyl-(1,1-biphenyl))ethylene monomer solution, based on the amount-of-substance concentration, that is, the amount of substance of the tetrakis(4-aminophenyl)methane monomer or the tetrakis(4-formyl-(1,1-biphenyl))ethylene monomer: the volume of the mixed solvent, are both n 单体 / V 混合溶剂 = 67 / 400 (mol / L); (2) Place the above monomer solution in a stainless-steel reactor with a polytetrafluoroethylene lining, and slowly dropwise add an aqueous catalyst solution. After the device is degassed and vacuum-sealed, react at 120 °C for 5 to 9 days; The concentration of the aqueous catalyst solution is 5 to 7 mol / L; Based on the molar ratio, the total amount of the monomers is 3 to 4 times the amount of the catalyst used; The catalyst includes at least one of acetic acid, sulfuric acid, and trifluoromethanesulfonic acid, preferably acetic acid; (3) After the reaction is completed, cool the device to room temperature, filter out the obtained precipitate, and wash the product alternately with tetrahydrofuran, acetone, and dichloromethane; (4) Drying: Vacuum-dry at 75 to 85 °C for 10 to 14 h to obtain a powdery product, namely the 3D-TPE-COF fluorescent material.

[0019] Step two, the preparation of a coating reflective film based on an organic fluorescent coating, the specific steps are as follows: (1) According to the formula, disperse the 3D-TPE-COF fluorescent material and polymer particles prepared in step one into a hydrogen-bond network dispersion solvent, ultrasonically disperse for 1 hour, and stir evenly to obtain a first suspension; 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); The hydrogen-bond network dispersion solvent includes at least one of carbon tetrachloride and tetrahydrofuran; (2) According to the formula, disperse the first suspension obtained in step (1), as well as an adhesive, a curing agent, and an antistatic agent, into a coating liquid dispersion solvent in sequence, and stir evenly to obtain a final coating liquid; The adhesive includes at least one of an acrylic resin adhesive, a polycarbonate resin adhesive, a polyurethane resin adhesive, and a polyimide resin adhesive, preferably an acrylic resin adhesive; The curing agent includes at least one of an isocyanate, an epoxy resin, a methyl phenolic resin, and dicyandiamide, preferably an isocyanate curing agent; The antistatic agent includes at least one of lithium bis(trifluoromethylsulfonyl)imide and lithium trifluoromethanesulfonate; the dispersion solvent of the coating solution includes at least one of N,N-dimethylformamide, ethyl acetate, and butyl acetate; (3) Coating the obtained coating solution on the surface of the substrate and curing it by heating in an oven to obtain a coated reflective film based on an organic fluorescent coating; The substrate includes at least one of a PET polyester film and a polypropylene film; The thermal curing temperature of the coating is 100-120°C, and the reaction time is 1-3 min.

[0020] The above-mentioned coated reflective film based on an organic fluorescent coating can be applied in a display module / display device; the display module includes at least one of an LCD module and a Mini-LED module; The display device includes at least one of a television, a mobile phone, a laptop computer, and a vehicle center control screen.

[0021] Compared with the prior art, the present invention has the following beneficial effects: (1) The reaction monomer TPE-Ph-CHO has a tetraphenylethylene (TPE) unit, making this material have the characteristics of an aggregation-induced emission (AIE) material; the TPE units aggregate in the three-dimensional COF framework, enabling 3D-TPE-COF to emit yellow light with a maximum emission wavelength of 543 nm and a relatively high fluorescence quantum yield; when the concentration of 3D-TPE-COF is higher, the material emits stronger light and has higher sensitivity; 3D-TPE-COF also has strong stability to ultraviolet excitation light and will not be photo-bleached; in addition, the reaction monomer has 4 reaction sites, which enables more TPE aggregation and stronger fluorescence of the material; the biphenyl and imine bonds have a conjugated structure, which also enhances the fluorescence; therefore, the present invention places the 3D-TPE-COF fluorescent material in the coating solution to prepare an organic fluorescent coating for converting the high-energy blue light leaked by the LED lamp, making the brightness of the backlight module higher and closer to white; (2) The 3D-TPE-COF fluorescent material is a [4+4] COF with a new topological structure, having a multi-interpenetrating point topological structure. Multiple interpenetrating networks are intertwined with each other to form a three-dimensional support framework, effectively dispersing external stresses and preventing the collapse of a single network. This structure significantly improves the thermal stability and mechanical strength of the material, especially showing excellent performance in high-temperature or high-pressure environments. Therefore, 3D-TPE-COF is resistant to organic chemical solvents during the liquid preparation process and is resistant to high temperatures during the thermal curing process. (3) The 3D-TPE-COF fluorescent material is formed by the Schiff base reaction of an aldehyde compound and a primary amine. Structurally, it has carbon-nitrogen double bonds and unreacted amino groups, while the polymer particles have H elements on their surfaces, and there is a tendency to form intermolecular interactions such as hydrogen bonds between the two. Therefore, the 3D-TPE-COF fluorescent material can form a hydrogen bond network with the polymer particles, avoiding the agglomeration of the polymer particles and improving the wear and scratch resistance of the coated reflective film. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Schematic structural diagram of a coated reflective film based on an organic fluorescent coating.

[0023] 1 - Polymer particles; 2 - 3D-TPE-COF fluorescent material; 3 - Organic fluorescent coating; 4 - Substrate.

[0024] Figure 2 Steady-state fluorescence spectrum of the 3D-TPE-COF fluorescent material (λ ex = 450 nm).

[0025] Figure 3 Synthesis equation of the 3D-TPE-COF fluorescent material. DETAILED DESCRIPTION OF THE INVENTION

[0026] The following are specific embodiments of the present invention, further describing the technical solutions of the present invention.

[0027] Unless otherwise specified, the materials used in the present invention are commercially available products, and the methods used are conventional technical means.

[0028] Tetrakis(4-aminophenyl)methane (TAPM): Analytically pure, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0029] Tetra-(4-aldehyde-(1,1-biphenyl))ethylene (TPE-Ph-CHO): Analytically pure, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0030] YAG:Ce³⁺ fluorescent material: Purchased from Jinhong Crystal Materials (Shanghai) Co., Ltd.

[0031] Example 1 A coated reflective film based on an organic fluorescent coating, the structural schematic diagram of which is as shown in the appendix Figure 1 as shown, including a substrate and an organic fluorescent coating, the organic fluorescent coating is formed by thermal curing of a coating solution, the coating solution includes a 3D-TPE-COF fluorescent material, the 3D-TPE-COF fluorescent material is a covalent organic framework material, adding it to the coating solution enables the obtained coated reflective film to convert high-energy blue light, so that the brightness of the backlight module is 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 solution to avoid agglomeration of polymer particles, improving the wear and scratch resistance of the coated reflective film. The specific preparation steps of this coated reflective film based on an organic fluorescent coating are as follows: Step 1, Preparation of 3D-TPE-COF fluorescent material, the corresponding synthesis equation is as shown in the appendix Figure 3 as shown, the specific preparation steps are as follows: (1) Disperse 2.55 g of tetra(4-aminophenyl)methane (TAPM) monomer and 5 g of tetra-(4-aldehyde-(1,1-biphenyl))ethylene (TPE-Ph-CHO) monomer in a mixed solvent of 20 mL of ortho-dichlorobenzene and 20 mL of mesitylene, and ultrasonically treat for 30 minutes to obtain a monomer solution; (2) Place the above monomer solution in a stainless steel reaction kettle with a polytetrafluoroethylene lining, and slowly add 6 mL of acetic acid aqueous solution (6 mol / L), degas and vacuum seal the device, and react at 120 °C for 7 days; (3) After the reaction is completed, cool the device to room temperature, filter out the obtained precipitate, and wash the product alternately with tetrahydrofuran, acetone and dichloromethane; (4) Vacuum dry at 80 °C for 12 h to obtain a powdery product of 3D-TPE-COF fluorescent material. The steady-state fluorescence spectrum of 3D-TPE-COF is measured by a fluorescence spectrometer FL3-111 (as shown in the appendix Figure 2 )

[0032] Step 2, Preparation of a coated reflective film based on an organic fluorescent coating, the specific steps are as follows: (1) Disperse 0.5 part of 3D-TPE-COF fluorescent material and 3.1 parts of polyethylene terephthalate polymer particles into 25 parts of carbon tetrachloride, ultrasonically disperse for 1 hour, and stir evenly to obtain a first suspension; (2) Disperse 35 parts of acrylic resin adhesive, 3.5 parts of isocyanate curing agent, 0.2 part of lithium bis(trifluoromethylsulfonyl)imide and the first suspension into 32.7 parts of ethyl acetate in sequence, and stir evenly to obtain a final coating solution; (3) The obtained coating solution was coated on the surface of the PET reflective substrate and cured by heating in an oven at 110 °C for 2 min to form an organic fluorescent coating, and the thickness of the organic fluorescent coating was 10 μm.

[0033] Example 2 A coated reflective film based on an organic fluorescent coating provided in Example 1, wherein the synthesis reaction time of the 3D-TPE-COF fluorescent material in Step 1 was 5 days, and the remaining steps remained unchanged.

[0034] Example 3 A coated reflective film based on an organic fluorescent coating provided in Example 1, wherein the synthesis reaction time of the 3D-TPE-COF fluorescent material in Step 1 was 9 days, and the remaining steps remained unchanged.

[0035] Example 4 A coated reflective film based on an organic fluorescent coating provided in Example 1, wherein the synthesis catalyst of the fluorescent material of 3D-TPE-COF in Step 1 was trifluoromethanesulfonic acid, and the remaining steps remained unchanged.

[0036] Example 5 A coated reflective film based on an organic fluorescent coating provided in Example 1, wherein the polymer particles were PMMA, and the remaining steps remained unchanged.

[0037] Example 6 A coated reflective film based on an organic fluorescent coating provided in Example 1, wherein the 3D-TPE-COF fluorescent material in Step 2 was 0.3 parts, the polyethylene terephthalate polymer particles were 3.3 parts, and the mass ratio of the polyethylene terephthalate polymer particles to the 3D-TPE-COF fluorescent material was 11:1.

[0038] Example 7 A coated reflective film based on an organic fluorescent coating provided in Example 1, wherein the 3D-TPE-COF fluorescent material in Step 2 was 0.9 parts, the polyethylene terephthalate polymer particles were 2.7 parts, and the mass ratio of the polyethylene terephthalate polymer particles to the 3D-TPE-COF fluorescent material was 3:1.

[0039] Comparative Example 1 A coated reflective film based on an organic fluorescent coating provided in Example 1. In the reflective film of Comparative Example 1, the 3D-TPE-COF fluorescent material was not added.

[0040] Comparative Example 2 A coated reflective film based on an organic fluorescent coating provided in Example 1, wherein the fluorescent material in Step 2 was a commercially available YAG:Ce³⁺ fluorescent material.

[0041] Comparative Example 3 A coated reflective film based on an organic fluorescent coating provided in Example 1, wherein, in Step 2, the 3D-TPE-COF fluorescent material 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%.

[0042] Comparative Example 4 A coated reflective film based on an organic fluorescent coating provided in Example 1, wherein, in Step 2, the 3D-TPE-COF fluorescent material is 0.1 part, 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%.

[0043] Comparative Example 5 A coated reflective film based on an organic fluorescent coating provided in Example 1, adjust tetra(4-aminophenyl)methane monomer in Step 1 to tris(4-aminophenyl)methane, and keep the rest of the steps unchanged.

[0044] Comparative Example 6 A coated reflective film based on an organic fluorescent coating provided in Example 1, adjust tetra-(4-formyl-(1,1-biphenyl))ethylene monomer in Step 1 to tetra-(4-formylphenyl)ethylene, and keep the rest of the steps unchanged.

[0045] Comparative Example 7 A coated reflective film based on an organic fluorescent coating provided in Example 1, adjust tetra(4-aminophenyl)methane monomer in Step 1 to tris(4-aminophenyl)methane, and at the same time adjust tetra-(4-formyl-(1,1-biphenyl))ethylene monomer to tetra-(4-formylphenyl)ethylene, and keep the rest of the steps unchanged.

[0046] According to the following method, evaluate the performance of the coated reflective films based on organic fluorescent coatings prepared in the above examples and comparative examples: (1) Luminance and CIE coordinate color coordinate test: Place the coated reflective film in a direct-lit quantum dot backlight module, and use a luminance meter BM-7A to measure the luminance and color coordinates; the luminance represents the light-emitting effect, and the CIE color coordinates represent the light-emitting color; (2) Scratch test: Take a 20*20 mm reflective film and stick it on the sample stage of a steel wool abrasion resistance testing machine. Under a 200g weight, rub the coated surface of the reflective film against the light guide plate back and forth for 50 cycles at a speed of 12 mm / s; then use a USB digital microscope to observe and compare the area of the light guide plate before and after friction; no obvious scratches is excellent, 1-5 scratch lines is good, 6-15 scratch lines is medium, and more than 15 scratch lines is poor.

[0047] The performance characterization results of each example and comparative example are shown in Table 1.

[0048] Table 1 Performance characterization results of Examples 1-7 and Comparative Examples 1-7

[0049] According to the results of Example 1 and Comparative Examples 1 and 2, adding the 3D-TPE-COF fluorescent material with yellow organic phosphor characteristics to the reflective film coating can reduce the blue light transmittance of the reflective film and improve the brightness of the reflective film. The CIE color coordinates of the assembled backlight module are (0.3291, 0.3309), which are close to the coordinates (0.33, 0.33) of standard pure white light. Moreover, the blue light transmittance of the reflective film is still low after being lit for 1000 h, indicating good stability. At the same time, the 3D-TPE-COF fluorescent material and polyethylene terephthalate polymer particles can form a hydrogen bond network, improving the abrasion and scratch resistance of the coated reflective film. The commercial YAG:Ce³⁺ rare earth fluorescent powder also has a similar optical effect, but its overall blue light conversion performance is lower than that of the 3D-TPE-COF fluorescent material. In addition, this material has a large hardness and poor processing performance. Adding it to the coating will cause the scratch resistance of the coated reflective film to deteriorate, and the coated reflective film is prone to scratching the light guide plate.

[0050] It can be seen from the results of Example 1 and Examples 2 and 3 that the synthesis time of the 3D-TPE-COF fluorescent material is also crucial. If the synthesis time is short, the optical performance of the 3D-TPE-COF fluorescent material does not meet the standard; if the time is long, the optical performance can meet the standard, but the material size is too large and it is not easy to disperse, resulting in a poor effect of forming a hydrogen bond network between the 3D-TPE-COF fluorescent material and the polymer particles.

[0051] It can be seen from the results of Example 1 and Example 4 that using a strong acid such as trifluoromethanesulfonic acid as the catalyst for synthesizing the 3D-TPE-COF fluorescent material will cause the blue light conversion effect of the coated reflective film based on the organic fluorescent coating to deteriorate, and there is a deviation between the color coordinates and the standard pure white light.

[0052] It can be seen from the results of Example 1 and Example 5 that the terminal groups of the polyethylene terephthalate polymer particles have carboxyl and hydroxyl groups, which can form a hydrogen bond network with the 3D-TPE-COF fluorescent material, avoiding the aggregation of polymer particles, and thus improving the abrasion and scratch resistance of the coated reflective film.

[0053] From the results of Example 1, Example 6, and Example 7, it can be seen that when the mass ratio of polyethylene terephthalate polymer particles to 3D-TPE-COF fluorescent material is relatively high, the hydrogen bond network effect between the two is average, and the scratch resistance of the coated reflective film is not significantly improved. When the addition amount of 3D-TPE-COF fluorescent material is relatively small, the blue light transmittance of the reflective film is high, and the brightness of the overall backlight module is low. When the mass ratio of polyethylene terephthalate polymer particles to 3D-TPE-COF fluorescent material is relatively low and the addition amount of 3D-TPE-COF fluorescent material is relatively large, the color coordinates of the backlight module are yellowish, the picture is yellowish, and the overall brightness also decreases.

[0054] From the results of Example 1, Comparative Example 3, and Comparative Example 4, it can be seen that when the addition amount of 3D-TPE-COF fluorescent material is too large, the color coordinates of the backlight module are seriously yellowish, and the overall brightness decreases. When the addition amount of 3D-TPE-COF fluorescent material is too small, both the optical effect and the hydrogen bond formation effect of the fluorescent material are not obvious.

[0055] Example 1 and Comparative Examples 5-7 investigated the optical properties of COFs materials prepared from organic monomers with different structural characteristics after being applied to the coated reflective film, and found that the selection of reaction monomers is also very crucial. In the present invention, the aldehyde and amine reaction monomers of the 3D-TPE-COF fluorescent material each have 4 reaction sites, which makes more TPE aggregated and the fluorescence of the product stronger; the aldehyde monomer has a biphenyl structure, and the original biphenyl structure is still retained after the reaction. Therefore, the biphenyl and imine bonds in the product are in a conjugated structure, enhancing the fluorescence of the material.

Claims

1. A coated 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 solution, and is characterized in that, The coating solution includes a 3D-TPE-COF fluorescent material, which is a covalent organic framework material, and its chemical structural formula is shown as follows: 。 2. The coated reflective film based on an organic fluorescent coating according to claim 1, wherein The 3D-TPE-COF fluorescent material is prepared by a solvothermal synthesis method using tetra(4-aminophenyl)methane and tetra-(4-formyl-(1,1-biphenyl))ethylene as reaction monomers, o-dichlorobenzene and mesitylene as reaction solvents, and under the action of a catalyst; the monomer dosage of tetra(4-aminophenyl)methane and tetra-(4-formyl-(1,1-biphenyl))ethylene is 1:1 in terms of molar ratio; the catalyst includes at least one of acetic acid, sulfuric acid, and trifluoromethanesulfonic acid.

3. The coating reflective film based on an organic fluorescent coating according to claim 2, wherein The coating solution further includes polymer particles, an adhesive, a curing agent, an antistatic agent, a hydrogen bond network dispersion solvent, and a coating solution dispersion solvent.

4. The coating reflective film based on an organic fluorescent coating according to claim 3, characterized in that, 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 solution.

5. The coated reflective film based on an organic fluorescent coating according to claim 4, wherein, By mass, the components of the coating solution include: 3D-TPE-COF fluorescent material: 0.3 to 0.9 wt%, polymer particles: 2.7 to 3.3 wt%, adhesive: 34 to 36 wt%, curing agent: 3 to 4 wt%, antistatic agent: 0.1 to 0.3 wt%, hydrogen bond network dispersion solvent: 24 to 26 wt%, and the balance is the coating solution dispersion solvent.

6. The coated reflective film based on an organic fluorescent coating according to claim 5, wherein, The polymer particles include at least one of polyethylene terephthalate, polymethyl methacrylate, polybutyl methacrylate, polyamide, and polyurethane; the hydrogen bond network dispersion solvent includes at least one of carbon tetrachloride and tetrahydrofuran; the adhesive includes at least one of an acrylic resin adhesive, a polycarbonate resin adhesive, a polyurethane resin adhesive, and a 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(trifluoromethanesulfonyl)imide and lithium trifluoromethanesulfonate; the coating solution dispersion solvent includes at least one of N,N-dimethylformamide, ethyl acetate, and butyl acetate.

7. The coated reflective film based on an organic fluorescent coating according to claim 6, wherein 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.

8. The preparation method of a coated reflective film based on an organic fluorescent coating according to any one of claims 1 to 7, characterized in that, The preparation steps of the coated reflective film are as follows: (1) According to the formula, disperse the 3D-TPE-COF fluorescent material and polymer particles into the hydrogen bond network dispersion solvent to obtain a first suspension; (2) According to the formula, sequentially disperse the first suspension obtained in step (1), the adhesive, the curing agent, and the antistatic agent into the coating solution dispersion solvent to obtain a final coating solution; (3) Coat the obtained coating solution on the surface of the reflective substrate and cure it by heating in an oven to obtain a coated reflective film based on the organic fluorescent coating.

9. The preparation method of a coated reflective film based on an organic fluorescent coating according to claim 8, characterized in that, The preparation steps of the 3D-TPE-COF fluorescent material are as follows: Disperse the tetrakis(4-aminophenyl)methane monomer and the tetrakis(4-formyl-(1,1-biphenyl))ethylene monomer in a mixed solvent of o-dichlorobenzene and mesitylene, add a catalyst dropwise, and react 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; In the mixed solvent of o-dichlorobenzene and mesitylene, by volume ratio, o-dichlorobenzene:mesitylene = 1:1; The solution concentrations of the tetrakis(4-aminophenyl)methane monomer and the tetrakis(4-formyl-(1,1-biphenyl))ethylene monomer, in terms of molar concentration, that is, the amount of substance: the volume of the mixed solvent, are both n 单体 / V 混合溶剂 = 67 mol / 400 L; The concentration of the catalyst aqueous solution is 5 to 7 mol / L; In terms of molar ratio, the total amount of the monomers is 3 to 4 times the amount of the catalyst used.

10. The preparation method of a coated reflective film based on an organic fluorescent coating according to claim 9, wherein The temperature of the thermal curing in step two is 100 to 120 °C, and the reaction time is 1 to 3 min.

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