Biomimetic patterned biomass-based photoluminescent polyurethane coating for leather and method of preparation thereof

Abstract

This invention discloses a method for preparing a biomimetic patterned biomass-based photoluminescent polyurethane coating for leather, specifically including the following steps: Step 1, preparing a zirconium hydrogen phosphate crosslinked dispersion; Step 2, preparing a biomimetic patterned biomass-based photoluminescent polyurethane emulsion for leather based on the product obtained in Step 1; Step 3, preparing a biomimetic patterned biomass-based photoluminescent polyurethane coating for leather based on the product obtained in Step 2. This invention also discloses a biomimetic patterned biomass-based photoluminescent polyurethane coating for leather, the prepared polyurethane coating possessing good pattern display function, suitable for leather finishing and anti-counterfeiting applications.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of leather coating, and relates to a biomimetic patterned biomass-based photoluminescent polyurethane coating for leather and a preparation method of the biomimetic patterned biomass-based photoluminescent polyurethane coating for leather. BACKGROUND

[0002] Polyurethane (PU) is a kind of high molecular polymer containing urethane groups, which is synthesized from polyisocyanate, polyol and small molecule diol or diamine. The molecular chain structure of PU contains hard segments (urethane segment) and soft segments (polyol segment). In the leather industry, PU is often used as the main component of high-performance finishing agent. PU has many characteristics such as simple preparation process, wide source, high solid content, high mechanical strength and good film forming performance. However, due to the inevitable environmental and human health risks of traditional solvent-based PU, in recent years, water-based PU has gradually become a green alternative to traditional solvent-based PU finishing agent because of its environmental safety, low viscosity and other characteristics, as well as excellent chemical resistance, flexibility and mechanical properties.

[0003] In recent years, the global consumer market has shown a growing demand for diversified and personalized leather products with functions such as flame retardation, antibiosis, luminescence, waterproofness, stain resistance, self-cleaning and electromagnetic / ultraviolet shielding. However, the existing PU leather finishing materials cannot meet the high performance technical requirements of leather products. At present, in the photoluminescent PU leather finishing material, the functional groups are mostly carbon quantum dots, but they may have certain safety risks, and their preparation controllability is poor and their compatibility with the PU matrix is also poor. Therefore, it is urgent to develop a new preparation system to develop high-performance patterned biomass-based polyurethane coatings for leather. SUMMARY

[0004] The purpose of the present application is to provide a preparation method of a biomimetic patterned biomass-based photoluminescent polyurethane coating for leather. The polyurethane coating prepared by the method has good pattern display function and can be used for leather finishing and anti-counterfeiting applications.

[0005] Another purpose of the present application is to provide a biomimetic patterned biomass-based photoluminescent polyurethane coating for leather.

[0006] The first technical solution adopted by the present application is a preparation method of a biomimetic patterned biomass-based photoluminescent polyurethane coating for leather, which specifically comprises the following steps:

[0007] Step 1, preparing a zirconium hydrogen phosphate crosslinking body dispersion liquid;

[0008] Step 2, preparing a biomimetic patterned biomass-based photoluminescent polyurethane emulsion for leather according to the product obtained in step 1;

[0009] Step 3: Preparation of biomimetic patterned biomass-based photoluminescent polyurethane coating for leather according to the product obtained in step 2.

[0010] The first technical solution of the present application is also characterized in that:

[0011] The specific process of step 1 is:

[0012] Step 1.1: The peeling agent solution is added dropwise to the zirconium hydrogen phosphate dispersion, and stirred uniformly at room temperature.

[0013] Step 1.2: Concentrated phosphoric acid is added dropwise to the zirconium hydrogen phosphate dispersion treated in step 1.1 to adjust the pH to acidic.

[0014] Step 1.3: The organic crosslinking agent solution is added dropwise to the zirconium hydrogen phosphate dispersion treated in step 1.2, and stirred uniformly at room temperature. Finally, deionized water is used for dialysis to remove unreacted crosslinking agent molecules, and the zirconium hydrogen phosphate crosslinked body dispersion is obtained.

[0015] In step 1.1, the molar ratio of zirconium hydrogen phosphate to peeling agent is 1: (6-8), and the peeling agent is any one of tetrabutylammonium hydroxide, propylamine, and allylamine.

[0016] In step 1.2, the pH range of the solution adjusted by using concentrated phosphoric acid is 1.5-2.5.

[0017] In step 1.3, the molar ratio of organic crosslinking agent to zirconium hydrogen phosphate is 1: (150-200), and the organic crosslinking agent is any one of tannic acid, gallic acid, caffeic acid, or dopamine.

[0018] The specific process of step 2 is:

[0019] The polyurethane solution, fluorescent agent, and zirconium hydrogen phosphate crosslinked body dispersion prepared in step 1 are mixed, and stirred uniformly at room temperature to obtain a biomimetic patterned biomass-based photoluminescent polyurethane emulsion for leather.

[0020] In step 2, the mass ratio of polyurethane solution to zirconium hydrogen phosphate crosslinked body dispersion to fluorescent agent is: 1: 0.01-0.05: 0.00005-0.00015.

[0021] In step 2, the polyurethane is any one of castor oil-based polyurethane, sorbitol-based polyurethane, or lignin-based polyurethane, and the solid content of polyurethane in the polyurethane solution is 20%; the fluorescent agent is any one of rhodamine 6G, rhodamine B, or fluorescein.

[0022] The specific process of step 3 is: The product obtained in step 2 is placed in a spray gun, and sprayed on the surface of the leather with a matching hollow pattern. Finally, the sprayed leather is placed in an oven, and after the water is completely volatilized, a biomimetic patterned coating for leather is obtained.

[0023] The second technical solution adopted in this invention is a biomimetic patterned biomass-based photoluminescent polyurethane coating for leather, which is prepared by the above-mentioned preparation method of the biomimetic patterned biomass-based photoluminescent polyurethane coating for leather.

[0024] The beneficial effects of this invention are as follows:

[0025] 1. This invention introduces two-dimensional nanosheet materials into a polyurethane coating, which can form a coating with a biomimetic structure of natural skin wrinkles on the leather surface, thereby enhancing the mechanical properties of the coating.

[0026] 2. Fluorescent pattern design is applied to the leather surface to enable the leather coating to display information and perform anti-counterfeiting functions.

[0027] 3. The materials used in this invention are widely available, inexpensive, environmentally friendly, and the method is simple, effective, and highly functional, making it a promising candidate for widespread application in the leather coating market. Attached Figure Description

[0028] Figure 1 The polyurethane composite film formed by the biomimetic patterned biomass-based photoluminescent polyurethane coating for leather prepared in Example 2 of the present invention has a structure similar to natural skin wrinkles.

[0029] Figure 2(a) shows the stress-strain curve of the polyurethane composite film formed by the biomimetic patterned biomass-based photoluminescent polyurethane coating for leather prepared by Example 2 of the preparation method of the present invention.

[0030] Figure 2(b) shows the toughness and Young's modulus of the polyurethane composite film formed by the biomimetic patterned biomass-based photoluminescent polyurethane coating for leather prepared by Example 2 of the preparation method of the present invention.

[0031] Figure 2(c) shows the effect of different deformations on the fluorescence color of the polyurethane composite film formed by the biomimetic patterned biomass-based photoluminescent polyurethane coating for leather prepared by Example 2 of the preparation method of the present invention.

[0032] Figure 3(a) is a photograph of the biomimetic patterned biomass-based photoluminescent polyurethane coating for leather prepared in Example 3 under sunlight;

[0033] Figure 3(b) is a photograph of the biomimetic patterned biomass-based photoluminescent polyurethane coating for leather prepared in Example 3 under ultraviolet light.

[0034] Figure 4(a) is a photograph of the biomimetic patterned biomass-based photoluminescent polyurethane coating for leather prepared in Example 4 under sunlight.

[0035] Figure 4(b) is a photograph of the biomimetic patterned biomass-based photoluminescent polyurethane coating for leather prepared in Example 4 under ultraviolet light. Detailed Implementation

[0036] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0037] The present invention discloses a method for preparing a biomimetic patterned biomass-based photoluminescent polyurethane coating for leather, which specifically includes the following steps: Step 1, preparing a zirconium hydrogen phosphate crosslinked dispersion, the specific process of which is as follows:

[0038] A 0.1 mol / L stripping agent solution was added dropwise to 100 mL of a 0.05 mol / L zirconium hydrogen phosphate dispersion, and the mixture was magnetically stirred at room temperature for 6 h. Then, 14.63 mol / L concentrated phosphoric acid was added dropwise to the dispersion to adjust the pH. Subsequently, 1 mg / mL of an organic crosslinking agent solution was added dropwise to the pH-adjusted dispersion, and the mixture was stirred at room temperature for 4 h to 8 h. Finally, the mixture was dialyzed with deionized water for 24 h to remove unreacted crosslinking agent molecules, resulting in an 8 mg / mL zirconium hydrogen phosphate crosslinked dispersion.

[0039] The stripping agent is any one of tetrabutylammonium hydroxide, propylamine, and allylamine;

[0040] The molar ratio of zirconium hydrogen phosphate to the stripping agent is 1:(6~8).

[0041] The pH of the solution should be adjusted to a range of 1.5 to 2.5 using concentrated phosphoric acid.

[0042] The organic crosslinking agent is any one of tannic acid, gallic acid, caffeic acid, or dopamine;

[0043] The molar ratio of the organic crosslinking agent to zirconium hydrogen phosphate is 1:(150~200).

[0044] Step 2, preparing a biomimetic patterned biomass-based photoluminescent polyurethane emulsion for leather, the specific process is as follows:

[0045] A polyurethane solution was mixed with a fluorescent agent and a zirconium hydrogen phosphate crosslinking dispersion and magnetically stirred at room temperature for 2 hours to obtain a biomimetic patterned biomass-based photoluminescent polyurethane emulsion for leather.

[0046] The polyurethane used is any one of castor oil-based polyurethane, sorbitol-based polyurethane, or lignin-based polyurethane, and the solid content of polyurethane in the polyurethane solution is 20%.

[0047] The fluorescent agent is any one of Rhodamine 6G, Rhodamine B, or fluorescein.

[0048] The mass ratio of polyurethane solution to zirconium hydrogen phosphate crosslinked dispersion and fluorescent agent is 1:0.01~0.05:0.00005~0.00015.

[0049] Step 3, preparing a biomimetic patterned biomass-based photoluminescent polyurethane coating for leather, the specific process is as follows:

[0050] Take the paint from step 2 and put it into a spray gun. Spray it onto the leather surface that fits the hollow pattern. Finally, place the sprayed leather in a 50°C oven and wait for the moisture to evaporate completely to obtain the biomimetic patterned coating for leather.

[0051] The leather type is either chrome-tanned or vegetable-tanned.

[0052] The spraying method involves three coats using a spray gun, with a coating volume of 50 mL / m². 2 .

[0053] The final product of this invention is a biomimetic patterned biomass-based photoluminescent polyurethane leather coating with a biomimetic structure of natural skin wrinkles, which can enhance the mechanical properties of the coating.

[0054] By spraying a pattern template onto the leather surface, a fluorescent coating can be formed, enabling the leather coating to display information and provide anti-counterfeiting features.

[0055] Example 1

[0056] 1.6 g of zirconium hydrogen phosphate was weighed and added to 100 mL of deionized water to obtain a 0.05 mol / L zirconium hydrogen phosphate dispersion. 5.68 g of tetrabutylammonium hydroxide was weighed and dissolved in 100 mL of deionized water to obtain a 0.32 mol / L tetrabutylammonium hydroxide solution. The tetrabutylammonium hydroxide solution was then slowly added dropwise to the zirconium hydrogen phosphate dispersion. The pH was adjusted to 1.5 by adding concentrated phosphoric acid dropwise to the dispersion. The mixture was magnetically stirred at room temperature for 6 h. Next, 50 mL of a 1 mg / mL tannic acid solution was prepared and added to the zirconium hydrogen phosphate solution. The mixture was stirred at room temperature for 4 h. The solution was then dialyzed with distilled water for 24 h using a 1000 Da dialysis bag to remove unreacted tannic acid, finally yielding an 8 mg / mL zirconium hydrogen phosphate crosslinked dispersion. Next, 10 mL of castor oil aqueous polyurethane emulsion with a solid content of 20% and 2 mL of 0.1 mg / mL rhodamine B solution were mixed with 2.5 mL of zirconium hydrogen phosphate crosslinking dispersion and stirred at room temperature for 2 hours to obtain a biomimetic patterned biomass-based photoluminescent polyurethane emulsion for leather. Finally, the polyurethane emulsion was loaded into a spray gun and sprayed evenly once on vegetable-tanned leather. It was then placed in a 50°C oven to dry. This process was repeated 3 times to obtain a biomimetic patterned biomass-based photoluminescent polyurethane coating for leather.

[0057] Example 2

[0058] 1.6 g of zirconium hydrogen phosphate was weighed and added to 100 mL of deionized water to obtain a 0.05 mol / L zirconium hydrogen phosphate dispersion. 5.68 g of tetrabutylammonium hydroxide was weighed and dissolved in 100 mL of deionized water to obtain a 0.32 mol / L tetrabutylammonium hydroxide solution, which was then slowly added dropwise to the zirconium hydrogen phosphate dispersion. The pH was adjusted to 2.5 by adding concentrated phosphoric acid dropwise to the dispersion. The mixture was magnetically stirred at room temperature for 6 h. Next, 50 mL of a 1 mg / mL tannic acid solution was prepared and added to the zirconium hydrogen phosphate solution. The mixture was stirred at room temperature for 8 h. The solution was then dialyzed against a 1000 Da dialysis bag with distilled water for 24 h to remove unreacted tannic acid, finally yielding an 8 mg / mL zirconium hydrogen phosphate crosslinked dispersion. Next, 10 mL of castor oil-based waterborne polyurethane with a solid content of 20% and 2 mL of 0.1 mg / mL rhodamine B solution were mixed with 2.5 mL of zirconium hydrogen phosphate crosslinking dispersion and stirred at room temperature for 2 hours to obtain a biomimetic patterned biomass-based photoluminescent polyurethane emulsion for leather. Finally, the polyurethane emulsion was loaded into a spray gun and sprayed evenly once on vegetable-tanned leather. It was then placed in a 50°C oven to dry and the process was repeated 3 times to obtain a biomimetic patterned biomass-based photoluminescent polyurethane coating for leather.

[0059] Since the biomimetic patterned biomass-based photoluminescent polyurethane emulsion for leather is mainly coated on the surface of leather to form a biomimetic patterned biomass-based photoluminescent polyurethane coating for leather, in order to characterize and test the structure and properties of the obtained coating, the polyurethane emulsion is usually uniformly poured onto a polytetrafluoroethylene plate and placed in an oven to obtain a polyurethane composite film. By characterizing the structure and properties of the film, its application performance as a leather coating can be compared, as follows:

[0060] To verify the mechanical properties of the biomimetic patterned biomass-based photoluminescent polyurethane emulsion for leather prepared in Example 2, 20 mL of the biomimetic patterned biomass-based photoluminescent polyurethane emulsion for leather prepared in Example 2 was uniformly poured onto a polytetrafluoroethylene plate and placed in an oven at 50°C for 16 hours to form a film, resulting in a photomechanical dual-response polyurethane composite film with excellent mechanical properties, and exhibiting fluorescence color changes affected by elongation under 365 nm ultraviolet light irradiation.

[0061] Example 3

[0062] 1.6 g of zirconium hydrogen phosphate was weighed and added to 100 mL of deionized water to obtain a 0.05 mol / L zirconium hydrogen phosphate dispersion. 1.77 g of propylamine was weighed and dissolved in 100 mL of deionized water to obtain a 0.3 mol / L propylamine solution, which was then slowly added dropwise to the zirconium hydrogen phosphate dispersion. The pH was adjusted to 2 by adding concentrated phosphoric acid dropwise to the dispersion. The mixture was magnetically stirred at room temperature for 6 h. Next, 50 mL of a 2 mg / mL gallic acid solution was prepared and added to the zirconium hydrogen phosphate solution. The mixture was stirred at room temperature for 6 h. The solution was then dialyzed against a 500 Da dialysis bag with distilled water for 24 h to remove unreacted gallic acid, finally yielding an 8 mg / mL zirconium hydrogen phosphate crosslinked dispersion. Next, 10 mL of sorbitol-based aqueous polyurethane with a solid content of 20% and 1 mL of 0.1 mg / mL fluorescein solution were mixed with 5 mL of zirconium hydrogen phosphate crosslinking dispersion and stirred at room temperature for 2 hours to obtain a biomimetic patterned biomass-based photoluminescent polyurethane emulsion for leather. Finally, it was loaded into a spray gun and sprayed evenly once on vegetable-tanned leather with a hollowed-out butterfly pattern. It was then dried in a 50°C oven and repeated 3 times to obtain a biomimetic patterned biomass-based photoluminescent polyurethane coating for leather, which could display a clear light yellow butterfly pattern under 365 nm ultraviolet light.

[0063] Example 4

[0064] 1.6 g of zirconium hydrogen phosphate was weighed and added to 100 mL of deionized water to obtain a 0.05 mol / L zirconium hydrogen phosphate dispersion. 2.36 g of allylamine was weighed and dissolved in 100 mL of deionized water to obtain a 0.4 mol / L tetrabutylammonium hydroxide solution, which was then slowly added dropwise to the zirconium hydrogen phosphate dispersion. The pH was adjusted to 2 by adding concentrated phosphoric acid dropwise to the dispersion. The mixture was magnetically stirred at room temperature for 6 h. Next, 50 mL of a 5 mg / mL caffeic acid solution was prepared and added to the zirconium hydrogen phosphate solution. The mixture was stirred at room temperature for 4 h. The solution was then dialyzed against a 500 Da dialysis bag with distilled water for 24 h to remove unreacted tannic acid, finally yielding an 8 mg / mL zirconium hydrogen phosphate crosslinked dispersion. Next, 10 mL of lignin-based waterborne polyurethane with a solid content of 20% and 1.5 mL of 0.1 mg / mL rhodamine 6G solution were mixed with 7.5 mL of zirconium hydrogen phosphate crosslinking dispersion and stirred at room temperature for 2 hours to obtain a biomimetic patterned biomass-based photoluminescent polyurethane emulsion for leather. Finally, it was loaded into a spray gun and sprayed evenly once on chrome-tanned leather with a hollowed-out butterfly pattern. It was then dried in a 50°C oven and repeated 3 times to obtain a biomimetic patterned biomass-based photoluminescent polyurethane coating for leather. It is almost invisible under sunlight, but can show a clear pale yellow butterfly pattern under 365 nm ultraviolet light, and has excellent anti-counterfeiting function.

[0065] Example 5

[0066] 1.6 g of zirconium hydrogen phosphate was weighed and added to 100 mL of deionized water to obtain a 0.05 mol / L zirconium hydrogen phosphate dispersion. 7.1 g of tetrabutylammonium hydroxide was weighed and dissolved in 100 mL of deionized water to obtain a 0.4 mol / L tetrabutylammonium hydroxide solution. The tetrabutylammonium hydroxide solution was then slowly added dropwise to the zirconium hydrogen phosphate dispersion. The pH was adjusted to 1.5 by adding concentrated phosphoric acid dropwise to the dispersion. The mixture was magnetically stirred at room temperature for 6 h. Next, 48 mL of a 2 mg / mL tannic acid solution was prepared and added to the zirconium hydrogen phosphate solution. The mixture was stirred at room temperature for 4 h. The solution was then dialyzed with distilled water for 24 h using a 1000 Da dialysis bag to remove unreacted tannic acid, finally yielding an 8 mg / mL zirconium hydrogen phosphate crosslinked dispersion. Next, 10 mL of castor oil-based waterborne polyurethane with a solid content of 20% and 2 mL of 0.1 mg / mL rhodamine B solution were mixed with 5 mL of zirconium hydrogen phosphate crosslinking dispersion and stirred at room temperature for 2 hours to obtain a biomimetic patterned biomass-based photoluminescent polyurethane emulsion for leather. Finally, the polyurethane emulsion was loaded into a spray gun and sprayed evenly once on vegetable-tanned leather. It was then placed in a 50°C oven to dry and repeated 3 times to obtain a biomimetic patterned biomass-based photoluminescent polyurethane coating for leather.

[0067] Example 6

[0068] 1.6 g of zirconium hydrogen phosphate was weighed and added to 100 mL of deionized water to obtain a 0.05 mol / L zirconium hydrogen phosphate dispersion. 5.68 g of tetrabutylammonium hydroxide was weighed and dissolved in 100 mL of deionized water to obtain a 0.32 mol / L tetrabutylammonium hydroxide solution. The tetrabutylammonium hydroxide solution was then slowly added dropwise to the zirconium hydrogen phosphate dispersion. The pH was adjusted to 2.5 by adding concentrated phosphoric acid dropwise to the dispersion. The mixture was magnetically stirred at room temperature for 6 h. Next, 36 mL of a 2 mg / mL tannic acid solution was prepared and added to the zirconium hydrogen phosphate solution. The mixture was stirred at room temperature for 2 h. The solution was then dialyzed against a 1000 Da dialysis bag with distilled water for 24 h to remove unreacted tannic acid, finally yielding an 8 mg / mL zirconium hydrogen phosphate crosslinked dispersion. Next, 10 mL of castor oil-based waterborne polyurethane with a solid content of 20% and 2 mL of 0.1 mg / mL rhodamine B solution were mixed with 8.3 mL of zirconium hydrogen phosphate crosslinking dispersion and stirred at room temperature for 2 hours to obtain a biomimetic patterned biomass-based photoluminescent polyurethane emulsion for leather. Finally, the polyurethane emulsion was loaded into a spray gun and sprayed evenly once on vegetable-tanned leather. It was then placed in a 50°C oven to dry and the process was repeated 3 times to obtain a biomimetic patterned biomass-based photoluminescent polyurethane coating for leather.

[0069] Figure 1 The image shows a SEM image of the photoluminescent polyurethane film prepared according to Example 2. The image reveals a distinct structure resembling natural skin wrinkles, which contributes to its excellent adhesion properties. Since films and coatings are inherently similar, the film structure is typically deduced from the coating structure.

[0070] Figure 2(a) shows the stress-strain curve of the polyurethane composite film formed by the biomimetic patterned biomass-based photoluminescent polyurethane emulsion for leather prepared by Example 2 of the preparation method of the biomimetic patterned biomass-based photoluminescent polyurethane coating for leather of the present invention (in Figure 2(a), I: polyurethane; II: polyurethane-nanosheet; III: polyurethane-nanosheet-organic crosslinking agent). As can be seen from Figure 2(a), Example 2 performs best in terms of strength and ductility, showing the highest stress and moderate strain.

[0071] Figure 2(b) shows the toughness and Young's modulus of the polyurethane composite film formed by the biomimetic patterned biomass-based photoluminescent polyurethane coating for leather prepared by Example 2 of the preparation method of the present invention (in Figure 2(b), I: polyurethane; II: polyurethane-nanosheet; III: polyurethane-nanosheet-organic crosslinking agent). It can be seen from Figure 2(b) that Example 2 exhibits the best performance in both toughness and Young's modulus, showing the highest toughness and Young's modulus.

[0072] Figure 2(c) shows the change in fluorescence color of the polyurethane composite film formed by different deformations of the biomimetic patterned biomass-based photoluminescent polyurethane emulsion for leather prepared by Example 2 of the preparation method of the present invention for biomimetic patterned biomass-based photoluminescent polyurethane coating for leather. As can be seen from Figure 2(c), under ultraviolet light, the fluorescence color becomes lighter with the increase of elongation, and it has mechanochromic properties.

[0073] Figure 3(a) is a photograph of the biomimetic patterned biomass-based photoluminescent polyurethane coating for leather prepared in Example 3 under sunlight; it can be seen from Figure 3(a) that it displays a clear butterfly image under normal lighting.

[0074] Figure 3(b) is a photograph of the biomimetic patterned biomass-based photoluminescent polyurethane coating for leather prepared in Example 3 under ultraviolet light. As can be seen from Figure 3(b), the polyurethane coating prepared in this invention displays a distinct butterfly image under ultraviolet light.

[0075] Figure 4(a) is a photograph of the biomimetic patterned biomass-based photoluminescent polyurethane coating for leather prepared in Example 4 under sunlight; it can be clearly seen in Figure 4(a) that the coating is almost invisible to the naked eye under sunlight;

[0076] Figure 4(b) is a photograph of the biomimetic patterned biomass-based photoluminescent polyurethane coating for leather prepared in Example 4 under ultraviolet light; it can be seen from Figure 4(b) that the polyurethane coating displays a bright pale yellow butterfly image under 365nm ultraviolet light.

[0077] As can be seen from Figures 3(a) and 3(b), and Figures 4(a) and 4(b), the polyurethane coating prepared by the present invention can be uniformly sprayed on leather, exhibits good adhesion performance, displays clear patterns, and has good anti-counterfeiting properties.

Claims

1. A method for preparing a biomimetic patterned biomass-based photoluminescent polyurethane coating for leather, characterized in that: Specifically, the steps include the following: Step 1, preparing a zirconium hydrogen phosphate crosslinked dispersion; the specific process of step 1 is as follows: Step 1.1: Add the stripping agent solution dropwise to the zirconium hydrogen phosphate dispersion and stir magnetically at room temperature until homogeneous; in Step 1.1, the molar ratio of zirconium hydrogen phosphate to stripping agent is 1:(6~8), and the stripping agent is any one of tetrabutylammonium hydroxide, propylamine, and allylamine; Step 1.2: Add concentrated phosphoric acid dropwise to the zirconium hydrogen phosphate dispersion treated in step 1.1 to adjust the pH to acidic; in step 1.2, the pH range of the solution adjusted by concentrated phosphoric acid is 1.5~2.

5. Step 1.3: The organic crosslinking agent solution is added dropwise to the zirconium hydrogen phosphate dispersion treated in Step 1.2, and stirred evenly at room temperature. Finally, unreacted crosslinking agent molecules are removed by dialysis with deionized water to obtain a zirconium hydrogen phosphate crosslinked dispersion. In Step 1.3, the molar ratio of organic crosslinking agent to zirconium hydrogen phosphate is 1:(150~200), and the organic crosslinking agent is any one of tannic acid, gallic acid, caffeic acid, or dopamine. Step 2: Prepare a biomimetic patterned biomass-based photoluminescent polyurethane emulsion for leather based on the product obtained in Step 1. The specific process of Step 2 is as follows: Mix the polyurethane solution, fluorescent agent, and the zirconium hydrogen phosphate crosslinked dispersion prepared in Step 1, and magnetically stir until homogeneous at room temperature to obtain the biomimetic patterned biomass-based photoluminescent polyurethane emulsion for leather. In Step 2, the mass ratio of the polyurethane solution to the zirconium hydrogen phosphate crosslinked dispersion and the fluorescent agent is 1:0.01~0.05:0.00005~0.00015. In Step 2, the polyurethane is any one of castor oil-based polyurethane, sorbitol-based polyurethane, or lignin-based polyurethane, and the solid content of the polyurethane in the polyurethane solution is 20%. The fluorescent agent is any one of Rhodamine 6G, Rhodamine B, or fluorescein. Step 3: Prepare a biomimetic patterned biomass-based photoluminescent polyurethane coating for leather based on the product obtained in Step 2. The specific process of Step 3 is as follows: Take the product obtained in Step 2 and put it into a spray gun, spray it on the leather surface with the hollowed-out pattern, and finally place the sprayed leather in an oven. After the moisture has completely evaporated, the biomimetic patterned coating for leather is obtained.

2. A biomimetic patterned biomass-based photoluminescent polyurethane coating for leather, prepared by the method described in claim 1.

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