Application of self-hydrophobic mildew-proof modified plain leather in material for shoes and preparation process of self-hydrophobic mildew-proof modified plain leather

Abstract

The invention discloses a self-hydrophobic mildew-proof modified plain leather material and a preparation process thereof. The self-hydrophobic mildew-proof modified plain leather material is prepared by coating modified polyurethane slurry, curing and attaching base cloth, the slurry comprises a bio-based single-component polyurethane resin solution, an amphiphilic functional conveying carrier solution, a biomass waste functional filler, a latent metal cross-linking prefabricated solution and an organic solvent, and the latent metal cross-linking prefabricated solution shields the activity of metal ions by utilizing volatile amine ligands, so that the slurry is effectively prevented from gelling in the storage period. The preparation process comprises the following steps: coating slurry to form a wet film, heating and curing through a program, and in a low-temperature stage, inducing the amphiphilic carrier to carry the filler to migrate and enrich towards the surface by utilizing a high-boiling-point solvent volatilization gradient; at the high-temperature stage, the ligand is promoted to volatilize to release metal ions, and the metal ions are subjected to in-situ coordination cross-linking with surface polyphenol and siloxane. According to the invention, a firm surface metal-organic micro-nano structure is constructed, the problem that the biomass filler is easy to fall off is solved, and the hydrophobicity, wear resistance and mildew resistance of the material are remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of polymer composite materials technology, specifically to the application and preparation process of self-hydrophobic and mildew-resistant modified leather in footwear materials. Background Technology

[0002] Vegan leather is widely used in footwear, bags, and furniture due to its appearance and feel being similar to natural leather and its excellent physical and mechanical properties. However, conventional vegan leather typically lacks sufficient hydrophobicity, and the polar groups in the polyurethane molecular chain easily absorb moisture. In high-temperature and high-humidity environments, it easily becomes a breeding ground for mold, leading to mold spots, discoloration, and even degradation on the material surface, seriously affecting the product's lifespan and hygiene performance.

[0003] Currently, the main methods for imparting hydrophobic and mildew-resistant properties to vegan leather include surface finishing and bulk blending. Surface finishing typically involves spraying or rolling a hydrophobic or mildew-resistant agent onto the surface of the vegan leather after it has been molded. While this method offers flexibility, the functional layer primarily adheres to the substrate surface through physical adsorption, resulting in poor bonding strength. In actual use, repeated friction or washing can easily cause the functional components to peel off, leading to functional failure.

[0004] However, metal ions with high anti-mildew properties or functional additives with high surface activity often have high chemical reactivity. Direct addition can easily induce premature cross-linking or aggregation of the resin system, leading to a sharp increase in slurry viscosity or even gelation in a short period of time. This significantly shortens the pot life of the slurry and makes it difficult to meet the needs of industrial continuous coating production. Furthermore, materials prepared by blending have a uniform distribution of functional components, and components embedded within the resin cannot exert surface hydrophobic or contact bactericidal effects, resulting in waste of raw materials. Therefore, developing a modified leather technology that can ensure production and processing stability while achieving surface enrichment and firm anchoring of functional components is a pressing problem in this field. Summary of the Invention

[0005] The technical problem solved by this invention is that existing bio-based polyurethane synthetic leather materials usually have problems such as poor surface hydrophobicity, insufficient wear resistance, and easy growth of mold in humid environments; and conventional surface physical coating modification processes have defects such as weak interlayer bonding and easy peeling, while directly adding functional additives often leads to poor storage stability of resin slurry or the inability of functional components to be effectively enriched on the surface.

[0006] To address the above problems, the present invention provides the following technical solution: In a first aspect, the present invention provides a self-hydrophobic and mildew-resistant modified leather material, which adopts the following technical solution: A self-hydrophobic and mildew-resistant modified leather material is made by coating, curing, and bonding a modified polyurethane slurry to a base fabric. The modified polyurethane slurry is made from raw materials comprising the following parts by weight: 100.0 parts of a bio-based single-component polyurethane resin solution; 4.0-10.0 parts of an amphiphilic functional transport carrier liquid; 3.0-10.0 parts of a biomass waste functional filler; 2.0-5.0 parts of a latent metal crosslinking pre-formulated liquid; and an organic solvent for adjusting viscosity.

[0007] By employing the above technical solution, this invention achieves hydrophobic, abrasion-resistant, and mildew-resistant functional modifications to the surface of vegan leather. The latent metal crosslinking pre-formed liquid forms complexes with metal ions through volatile amine ligands, inhibiting the catalytic and crosslinking activity of metal ions at room temperature and ensuring the storage stability of the modified slurry. The amphiphilic functional delivery carrier liquid utilizes the difference in evaporation rates between the high-boiling-point co-solvent and the main solvent to deliver plant polyphenols, side-chain amino-modified polysiloxanes, and biomass waste functional fillers to the coating surface during the drying process. During the high-temperature curing stage, the amine ligands volatilize, releasing metal ions that undergo in-situ coordination reactions with the surface-enriched plant polyphenols and side-chain amino-modified polysiloxanes, forming a metal-organic network. This network fixes the biomass waste functional fillers to the material surface, thereby improving the surface roughness, hydrophobicity, and abrasion resistance of the material.

[0008] Preferably, the latent metal crosslinking preform is prepared from raw materials including metal salts, volatile amine ligands, and alcohol solvents; wherein the molar ratio of the metal salt to the volatile amine ligand is 1:(2.0-6.5). By adopting the above technical solution, sufficient volatile amine ligands ensure that metal ions form a stable coordination structure, preventing free metal ions from causing slurry thickening or gelation; at the same time, the alkaline environment provided by the ligands helps to inhibit the oxidative self-polymerization of polyphenol components.

[0009] Preferably, the amphiphilic functional delivery carrier liquid is prepared by dispersing raw materials including plant polyphenol extracts, side-chain amino-modified polysiloxanes, and high-boiling-point co-solvents; wherein the mass ratio of the plant polyphenol extracts, side-chain amino-modified polysiloxanes, and high-boiling-point co-solvents is (1.0-2.0):(1.5-3.0):(3.0-5.0). By adopting the above technical solution, the side-chain amino-modified polysiloxanes reduce surface energy, the plant polyphenols provide coordination sites and bioactivity, and the high-boiling-point co-solvent maintains the solubility of the functional components during the evaporation stage of the low-boiling-point solvent and acts as a carrier to promote the directional migration of functional components to the gas-liquid interface.

[0010] Preferably, the biomass waste functional filler is selected from modified coffee grounds powder, sugarcane bagasse nanocellulose, or tea residue powder; the metal salt is selected from anhydrous zinc acetate or anhydrous ferric chloride; the volatile amine ligand is selected from ethylenediamine or n-butylamine; the plant polyphenol extract is selected from tea polyphenols, citrus peel extract, or tannic acid; and the high-boiling-point co-solvent is selected from dipropylene glycol methyl ether or ethylene glycol monobutyl ether, with a boiling point higher than that of the volatile amine ligand. By adopting the above technical solution, the boiling point difference between the high-boiling-point co-solvent and the volatile amine ligand is utilized to ensure that the solvent gradient migration process is completed before the cross-linking reaction initiated by ligand volatilization, thereby achieving the orderly surface construction of functional components.

[0011] Secondly, the present invention provides a preparation process for a self-hydrophobic and mildew-resistant modified leather material, employing the following technical solution: A preparation process for a self-hydrophobic and mildew-resistant modified leather material includes the following steps: S1, preparation of modified slurry: The amphiphilic functional transport carrier liquid is added to a single-component polyurethane resin solution and dispersed evenly. Then, the biomass waste functional filler is added and dispersed until there is no particulate matter. The latent metal crosslinking pre-prepared liquid is added, and an organic solvent is added to adjust the viscosity and degas, resulting in a modified polyurethane slurry; S2, coating: The modified polyurethane slurry obtained in step S1 is coated onto a patterned release paper to form a wet film; S3, programmed temperature curing: The release paper coated with the wet film in step S2 is heated and dried in stages. The solvent evaporation gradient induces the functional components to carry the biomass waste functional filler to the surface and undergo in-situ crosslinking and anchoring to form a cured film; S4, post-treatment: The cured film obtained in step S3 is bonded to a base fabric in a semi-molten state. After curing, cooling, and peeling off the release paper, the self-hydrophobic and mildew-resistant modified leather material is obtained.

[0012] By employing the above technical solution, the microstructure of the material surface is constructed using programmed temperature-curing. In the first drying stage, the temperature is below the boiling point of the amine ligands, causing the low-boiling-point solvent to evaporate. The high-boiling-point co-solvent carries the functional filler and carrier liquid to the wet film surface for enrichment. At this time, the metal ions are in a coordination latent state and do not undergo cross-linking reactions, ensuring unobstructed migration channels. In the second drying stage, the temperature is above the boiling point of the amine ligands, causing the ligands to evaporate rapidly. The reactivated metal ions then chemically cross-link with the polyphenols and polysiloxanes enriched on the surface. This process constructs a high-density metal-organic interpenetrating network on the resin surface in a one-step manner, achieving physical encapsulation and chemical fixation of biomass waste functional fillers, thus solving the problem of filler detachment.

[0013] Preferably, the preparation method of the latent metal crosslinking preform includes: dissolving a metal salt in anhydrous ethanol, adding a volatile amine ligand dropwise under stirring conditions at 5℃-30℃, and sealing and stirring the reaction after the addition is completed within 15-45 minutes to obtain a clear and transparent or colored transparent liquid. By adopting the above technical solution, low temperature and controlled dropping rate can prevent side reactions caused by local exothermic reactions, ensuring the preparation of a uniform and stable latent crosslinking liquid.

[0014] Preferably, the preparation method of the amphiphilic functional delivery carrier liquid includes: dissolving plant polyphenol extract in a high-boiling-point co-solvent heated to 40-50°C, then adding side-chain amino-modified polysiloxane, and dispersing the mixture using a high-speed disperser to obtain a homogeneous liquid. By adopting the above technical solution, pre-mixing the polyphenols and siloxane in a high-boiling-point solvent is beneficial for forming a stable dispersion system, promoting its uniform dispersion in the polyurethane matrix and subsequent overall migration.

[0015] Preferably, the programmed temperature curing in step S3 specifically involves passing the release paper coated with the wet film in step S2 through two drying stages: First drying stage: setting the first heating temperature to 65-90°C and the residence time to 2-4 minutes; the first heating temperature is set below the boiling point of the volatile amine ligands to prevent the release of metal ions while inducing the amphiphilic functional transport carrier liquid and biomass waste functional filler to migrate and accumulate on the wet film surface using the solvent evaporation gradient; Second drying stage: setting the second heating temperature to 120-150°C and the residence time to 2-3 minutes; the second heating temperature is set above the boiling point of the volatile amine ligands to promote the evaporation of the volatile amine ligands and release the coordination shielding of metal ions, thereby initiating in-situ crosslinking between metal ions and polyphenol compounds.

[0016] Preferably, in step S2, the viscosity of the modified polyurethane slurry is controlled at 2500-4000 mPa·s, and the wet film thickness is 100-150 μm. By adopting the above technical solution, controlling the slurry viscosity and film thickness ensures both the leveling properties of the coating process and provides a suitable liquid phase environment and path length for solvent gradient migration.

[0017] Thirdly, the present invention provides an application of the above-mentioned self-hydrophobic and mildew-resistant modified leather material, using the following technical solution: The application of the above-mentioned self-hydrophobic and mildew-resistant modified leather material in the preparation of shoe upper materials, shoe lining materials or insole fabrics.

[0018] By adopting the above technical solution, the material is applied to footwear products. The metal-polyphenol-siloxane network on the surface and the biomass filler together construct a micro-nano rough structure, giving the material surface excellent hydrophobic and anti-fouling properties. At the same time, the plant polyphenols fixed in the network and the metal ions have synergistic antibacterial activity, which can inhibit the growth of fungi such as Aspergillus niger and Chaetomium globosum in humid environments.

[0019] This invention provides the application and preparation process of self-hydrophobic and mildew-resistant modified leather in footwear materials. It offers the following beneficial effects: 1. This invention employs a latent metal crosslinking pre-liquid composed of metal salts and volatile amine ligands. By utilizing the coordination shielding effect of amine ligands on metal ions at room temperature, the chemical contact between metal ions and active groups in plant polyphenols and polyurethane resins is effectively blocked. This prevents the modified slurry from experiencing a sharp increase in viscosity or irreversible gelation due to rapid crosslinking reactions during storage and coating stages. It significantly extends the pot life of the modified slurry and ensures the leveling performance during coating processing, thus achieving storage stability control of metal-containing bio-based slurries.

[0020] 2. This invention introduces an amphiphilic functional transport carrier liquid containing a high-boiling-point co-solvent and combines it with a programmed temperature curing process. By utilizing the difference in evaporation rates between the high-boiling-point co-solvent and the main solvent, a solvent migration channel is formed from the inside out. This drives the directional migration and enrichment of plant polyphenols, side-chain amino-modified polysiloxanes, and biomass waste functional fillers to the gas-liquid interface during the wet film drying process. This achieves a high-density distribution of functional components on the surface of vegan leather without the need for additional spraying and post-treatment processes, and constructs a surface hydrophobic and mildew-resistant functional layer with a micro-nano rough structure.

[0021] 3. This invention utilizes the in-situ crosslinking reaction initiated by the removal of volatile amine ligands at high temperatures to promote the construction of a stable metal-organic coordination network by revitalized metal ions and surface-enriched plant polyphenols and side-chain amino-modified polysiloxanes. This network not only endows the material with long-lasting broad-spectrum antibacterial activity through the synergistic effect of metal ions and polyphenols, but also tightly wraps and anchors the biomass waste functional filler to the resin surface in physical space, effectively preventing the physical shedding of the filler during mechanical friction, and achieving simultaneous improvement in the hydrophobicity, mildew resistance and wear resistance of the vegan leather material surface. Attached Figure Description

[0022] Figure 1 This is a flowchart illustrating the preparation process of the self-hydrophobic and mildew-resistant modified leather material of the present invention. Detailed Implementation

[0023] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] Please see the appendix Figure 1 This invention provides the application and preparation process of self-hydrophobic and mildew-resistant modified leather in footwear materials.

[0025] The main raw materials and reagents used in the following examples and comparative examples have the following sources and specifications. Reagents not specifically mentioned are all commercially available analytical grade or higher grade products.

[0026] Bio-based single-component polyurethane resin solution, with a bio-based content ≥30% (derived from castor oil or soybean oil polyols), a solid content of 30%±2%, an organic solvent of N,N-dimethylformamide and toluene, a viscosity of 40000-50000 mPa·s (25℃), and no free isocyanate groups.

[0027] Amino-modified polysiloxane with side chain, ammonia value of 0.6-0.8 mmol / g, and viscosity of 300-500 cSt (25℃).

[0028] Plant polyphenol extracts are selected from tea polyphenols (derived from tea residue, with EGCG content ≥40%) or citrus peel extracts (derived from dried tangerine peel waste, with total flavonoid content ≥80%).

[0029] Anhydrous zinc acetate, purity ≥99.5%.

[0030] Anhydrous ferric chloride, purity ≥98.0%.

[0031] Ethylenediamine, purity ≥ 99.5%.

[0032] n-Butylamine, purity ≥99.0%.

[0033] Dipropylene glycol methyl ether (DPM), purity ≥ 99.0%.

[0034] Ethylene glycol monobutyl ether (BCS), purity ≥99.0%.

[0035] N,N-Dimethylformamide (DMF), analytical grade; Modified coffee grounds micro powder: particle size D50<10μm, after drying and surface treatment with coupling agent.

[0036] Sugarcane bagasse nanocellulose (CNF): diameter 20-50nm, aspect ratio >100.

[0037] Preparation example: Preparation Example A1: This preparation example provides a latent metal crosslinking preform, comprising the following steps: 10.0 g of anhydrous zinc acetate is weighed and dissolved in 40.0 g of anhydrous ethanol. Under the conditions of room temperature and stirring at 500 rpm, 13.1 g of ethylenediamine is slowly added dropwise. After the addition is completed, the container is sealed and stirring is continued for 30 minutes to obtain a clear and transparent liquid.

[0038] Preparation Example A2: This preparation example provides a latent metal crosslinking prepreg, comprising the following steps: 10.0g of anhydrous zinc acetate is weighed and dissolved in 40.0g of anhydrous ethanol. Under the conditions of room temperature and stirring at 500rpm, 19.7g of ethylenediamine is slowly added dropwise. After the addition is completed, the container is sealed and stirring is continued for 30 minutes to obtain a clear and transparent liquid.

[0039] Preparation Example A3: This preparation example provides a latent metal crosslinking preform, comprising the following steps: 10.0 g of anhydrous ferric chloride is weighed and dissolved in 50.0 g of anhydrous ethanol. Under the conditions of room temperature and stirring at 500 rpm, 27.0 g of n-butylamine is slowly added dropwise. After the addition is completed, the container is sealed and stirring is continued for 30 minutes to obtain a reddish-brown transparent liquid.

[0040] Preparation Example B1: This preparation example provides an amphiphilic functional delivery carrier liquid, comprising the following steps: weighing 10.0 g of tea polyphenol extract (derived from tea residue) and adding it to 30.0 g of dipropylene glycol methyl ether (DPM), heating to 45°C and stirring until the extract powder is completely dissolved; then adding 20.0 g of side-chain amino-modified polysiloxane, and dispersing it at 1500 rpm for 20 minutes using a high-speed disperser to obtain a brown homogeneous liquid.

[0041] Preparation Example B2: This preparation example provides an amphiphilic functional delivery carrier liquid, comprising the following steps: weighing 10.0 g of tannic acid and adding it to 30.0 g of dipropylene glycol methyl ether (DPM), heating to 45°C and stirring until the tannic acid is completely dissolved; then adding 15.0 g of side-chain amino-modified polysiloxane, and dispersing it for 20 minutes at 1500 rpm using a high-speed disperser to obtain a brown homogeneous liquid.

[0042] Preparation Example B3: This preparation example provides an amphiphilic functional delivery carrier liquid, comprising the following steps: weighing 10.0 g of tannic acid and adding it to 50.0 g of ethylene glycol monobutyl ether (BCS), heating to 45°C and stirring until the tannic acid is completely dissolved; then adding 30.0 g of side-chain amino-modified polysiloxane, and dispersing it for 20 minutes at 1500 rpm using a high-speed disperser to obtain a brown homogeneous liquid.

[0043] It is important to note that: 1. Regarding room temperature: This refers to an environmental condition with a temperature range of 5℃-30℃, preferably 20℃-25℃. Within this temperature range, the solubility of metal salts in ethanol is suitable, and the volatilization loss of volatile amine ligands is controllable.

[0044] 2. Regarding stirring conditions: This refers to the stirring state that enables the reaction system to form effective macroscopic mixing (such as the formation of a stable central vortex). In laboratory beaker or flask scale (such as the preparation amount of less than 100g as described in this embodiment), the stirring rate is preferably controlled at 300-800 rpm. In industrial scale-up production, this rate can be adjusted accordingly based on the reactor diameter and impeller type to achieve the same mixing effect.

[0045] 3. Regarding slow addition: This refers to controlling the flow rate of the added liquid to prevent precipitation due to excessively high local concentrations or drastic temperature fluctuations caused by exothermic reactions. In the laboratory preparation scale described in this embodiment, the duration of this addition process is typically controlled between 15 and 45 minutes (i.e., an average dropping rate of approximately 0.5-2.0 g / min). The specific duration can be fine-tuned depending on the clarity of the system and temperature changes, with the endpoint determined by the absence of permanent turbidity during the addition process.

[0046] Example: Example 1: This embodiment provides a process for preparing self-hydrophobic and mildew-resistant modified leather in footwear materials, including the following steps: (1) Preparation of modified slurry: 100.0 parts by weight of single-component polyurethane resin solution was added to a stirring tank. At a stirring speed of 500 rpm, 7.0 parts by weight of the amphiphilic functional transport carrier liquid provided in Preparation Example B1 was added and stirred for 15 minutes until it was evenly dispersed. Then, 8.0 parts by weight of modified coffee grounds powder was added and dispersed at high speed for 20 minutes until there was no particle feel. Then, the speed was reduced to 300 rpm, 3.5 parts by weight of the latent metal crosslinking prepreg provided in Preparation Example A1 was added, and an appropriate amount of DMF was added to adjust the slurry viscosity to 3000 mPa·s. Stirring was continued for 10 minutes and vacuum degassing was performed to obtain modified polyurethane slurry. (2) Coating: The modified slurry was coated onto the patterned release paper by means of a dry transfer coating process, and the wet film thickness was controlled at 120 μm. (3) Curing by temperature program: The coated release paper is sent into the oven for segmented drying. The temperature of the first stage is set at 80°C and the dwell time is 3 minutes. The functional components are induced to migrate to the surface by solvent gradient. At this time, the temperature is lower than the boiling point of the ligand ethylenediamine (117°C) and the metal ions remain in a latent state. The temperature of the second stage is set at 135°C and the dwell time is 2.5 minutes. The ligand is induced to volatilize and the in-situ crosslinking and locking of the metal-polyphenol network is activated. (4) Post-processing: The microfiber base fabric is bonded in a semi-molten state, cured at 60°C for 12 hours, cooled to room temperature, and the release paper is peeled off to obtain the target vegan leather material.

[0047] Example 2: This embodiment provides a process for preparing self-hydrophobic and mildew-resistant modified leather in footwear materials, including the following steps: (1) Preparation of modified slurry: 100.0 parts by weight of single-component polyurethane resin solution was added to a stirred tank. At a stirring speed of 500 rpm, 4.0 parts by weight of the amphiphilic functional transport carrier liquid provided in Preparation Example B2 was added, and 3.0 parts by weight of sugarcane bagasse nanocellulose (CNF) was added. The mixture was stirred and dispersed evenly. Then the speed was reduced to 300 rpm, 2.0 parts by weight of the latent metal crosslinking pre-solution provided in Preparation Example A1 was added, and an appropriate amount of DMF was added to adjust the slurry viscosity to 2500 mPa·s. The mixture was stirred for 10 minutes and then subjected to vacuum degassing treatment to obtain modified polyurethane slurry. (2) Coating: The modified slurry is coated onto the patterned release paper by means of a dry transfer coating process, and the wet film thickness is controlled at 100 μm. (3) Curing by temperature program: The coated release paper is sent into the oven for segmented drying. The temperature of the first stage is set at 70°C and the dwell time is 4 minutes. The functional components are induced to migrate to the surface by solvent gradient. The temperature of the second stage is set at 120°C and the dwell time is 3 minutes. The ligands are volatilized and the in-situ crosslinking and locking of the metal-polyphenol network are activated. (4) Post-processing: The woven base fabric is bonded in a semi-molten state, cured at 50°C for 24 hours, cooled to room temperature, and the release paper is peeled off to obtain the target vegan leather material.

[0048] Example 3: This embodiment provides a process for preparing self-hydrophobic and mildew-resistant modified leather in footwear materials, including the following steps: (1) Preparation of modified slurry: 100.0 parts by weight of single-component polyurethane resin solution was added to a stirring tank. At a stirring speed of 600 rpm, 10.0 parts by weight of the amphiphilic functional transport carrier liquid provided in Preparation Example B3 was added and stirred for 20 minutes until it was evenly dispersed. Then, 6.0 parts by weight of tea residue powder was added and dispersed at high speed for 20 minutes until there was no particle feel. Then, the speed was reduced to 300 rpm, 5.0 parts by weight of the latent metal crosslinking prepreg provided in Preparation Example A2 was added, and an appropriate amount of DMF was added to adjust the slurry viscosity to 4000 mPa·s. Stirring was continued for 10 minutes and vacuum degassing was performed to obtain modified polyurethane slurry. (2) Coating: The modified slurry is coated onto the patterned release paper by means of a dry transfer coating process, and the wet film thickness is controlled at 150 μm. (3) Curing by temperature program: The coated release paper is sent into the oven for segmented drying. The temperature of the first stage is set at 90°C and the dwell time is 2 minutes. The functional components are induced to migrate to the surface by solvent gradient. The temperature of the second stage is set at 150°C and the dwell time is 2 minutes. The ligands are volatilized quickly and the in-situ crosslinking and locking of the metal-polyphenol network is activated. (4) Post-processing: The microfiber base fabric is bonded in a semi-molten state, cured at 60°C for 12 hours, cooled to room temperature, and the release paper is peeled off to obtain the target vegan leather material.

[0049] Example 4: This embodiment provides a process for preparing self-hydrophobic and mildew-resistant modified leather in footwear materials, including the following steps: (1) Preparation of modified slurry: 100.0 parts by weight of single-component polyurethane resin solution was added to a stirred tank. At a stirring speed of 500 rpm, 7.0 parts by weight of the amphiphilic functional transport carrier liquid provided in Preparation Example B1 was added and stirred for 15 minutes until it was evenly dispersed. Then, 5.0 parts by weight of sugarcane bagasse nanocellulose (CNF) was added and dispersed at high speed for 20 minutes. Then, the speed was reduced to 300 rpm, 3.5 parts by weight of the latent metal crosslinking pre-solution (iron-based) provided in Preparation Example A3 was added, and an appropriate amount of DMF was added to adjust the slurry viscosity to 3000 mPa·s. Stirring was continued for 10 minutes and vacuum degassing was performed to obtain modified polyurethane slurry. (2) Coating: The modified slurry was coated onto the patterned release paper by means of a dry transfer coating process, and the wet film thickness was controlled at 120 μm. (3) Curing by temperature program: The coated release paper is sent into the oven for segmented drying. The temperature of the first stage is set at 65°C and the residence time is 4 minutes. This temperature is strictly lower than the boiling point of the ligand n-butylamine (77.1°C) to ensure that metal ions do not prematurely release during the solvent gradient induced migration stage. The temperature of the second stage is set at 140°C and the residence time is 2.5 minutes to induce the rapid volatilization of n-butylamine and stimulate the in-situ cross-linking and locking of iron ions with the polyphenol network. (4) Post-processing: The microfiber base fabric is bonded in a semi-molten state, cured at 60°C for 12 hours, cooled to room temperature, and the release paper is peeled off to obtain the target vegan leather material.

[0050] Example 5: This embodiment provides a process for preparing self-hydrophobic and mildew-resistant modified leather in footwear materials, including the following steps: (1) Preparation of modified slurry: 100.0 parts by weight of single-component polyurethane resin solution was added to a stirring tank. At a stirring speed of 500 rpm, 8.0 parts by weight of the amphiphilic functional transport carrier liquid provided in Preparation Example B2 was added and stirred for 15 minutes until it was evenly dispersed. Then, 8.0 parts by weight of modified coffee grounds powder was added and dispersed at high speed for 20 minutes until there was no particle feel. Then, the speed was reduced to 300 rpm, 4.0 parts by weight of the latent metal crosslinking prepreg provided in Preparation Example A1 was added, and an appropriate amount of DMF was added to adjust the slurry viscosity to 3500 mPa·s. Stirring was continued for 10 minutes and vacuum degassing was performed to obtain modified polyurethane slurry. (2) Coating: The modified slurry was coated onto the patterned release paper by means of a dry transfer coating process, and the wet film thickness was controlled at 130 μm. (3) Curing by temperature program: The coated release paper is sent into the oven for segmented drying. The temperature of the first stage is set at 75°C and the dwell time is 3.5 minutes. The functional components are induced to migrate to the surface by solvent gradient. The temperature of the second stage is set at 130°C and the dwell time is 3 minutes. The ligands are volatilized and the in-situ crosslinking and locking of the metal-polyphenol network are activated. (4) Post-processing: The microfiber base fabric is bonded in a semi-molten state, cured at 60°C for 12 hours, cooled to room temperature, and the release paper is peeled off to obtain the target vegan leather material.

[0051] Comparative example: Comparative Example 1 (Blank Control): Compared with Example 1, the difference is that the latent metal crosslinking prepreg provided in Preparation Example A1 and the amphiphilic functional delivery carrier liquid provided in Preparation Example B1 were not added. Only a pure single-component polyurethane resin solution was used for preparation. All other steps and parameters were the same.

[0052] Comparative Example 2 (verifying the necessity of metal anchoring): Compared with Example 1, the difference is that the latent metal crosslinking preform provided in Preparation Example A1 was not added, and only the amphiphilic functional delivery carrier liquid provided in Preparation Example B1 was added. The remaining steps and parameters are the same.

[0053] The purpose of this comparative example is to demonstrate that, without the coordination locking of metal ions, functional components can migrate but are easily lost after wear or washing.

[0054] Comparative Example 3 (verifying the necessity of latent ligand blocking): Compared with Example 1, the difference is that Preparation Example A1 was replaced with an equimolar amount of pure anhydrous zinc acetate ethanol solution (i.e., without the volatile ligand ethylenediamine), and the zinc acetate solution was added directly after the amphiphilic functional delivery carrier solution was added. All other steps and parameters were the same.

[0055] The purpose of this comparative example is to demonstrate that directly adding highly active metal ions will cause the slurry to gel instantly or precipitate, making subsequent coating impossible, thus proving the criticality of latent technology.

[0056] Comparative Example 4 (verifying the necessity of solvent gradient-induced migration): Compared with Example 1, the difference is that in the preparation of the amphiphilic functional delivery carrier liquid (corresponding to Preparation Example B1), the high-boiling-point solvent dipropylene glycol methyl ether (DPM, boiling point 190°C) was replaced with an equal weight of the low-boiling-point solvent butanone (MEK, boiling point 79.6°C), and the other steps and parameters were the same.

[0057] The purpose of this comparative example is to demonstrate that without the pumping effect of a high-boiling-point co-solvent, functional components cannot be effectively enriched on the surface, resulting in poor surface hydrophobic and mildew-proof effects.

[0058] Comparative Example 5 (Verifying the necessity of plant polyphenol anchoring agents): Compared with Example 1, the difference is that: in the preparation of the amphiphilic functional delivery carrier liquid, no plant polyphenol extract (tea polyphenol) was added, and only 20.0g of side-chain amino-modified polysiloxane was dispersed in 30.0g of dipropylene glycol methyl ether to prepare a polyphenol-free carrier liquid; in the modified slurry preparation step S1, the polyphenol-free carrier liquid was added, and the amount of other biomass filler (coffee grounds) added and the process steps were consistent with those of Example 1.

[0059] The purpose of this comparative example is to demonstrate that without the construction of a metal-organic network by plant polyphenols, biomass fillers (coffee grounds / cellulose) cannot be effectively encapsulated and anchored, resulting in powder shedding on the surface and poor wear resistance. The simple combination of metal and amino silicone oil cannot form a strong interpenetrating network, resulting in poor wear resistance and no anti-mildew function.

[0060] Comparative Example 6 (Compared to traditional surface spraying process): Compared with Example 1, the difference is that a two-step process is used. First, an unmodified one-component polyurethane resin solution is coated and dried to form a film; then, Preparation Example A1 and Preparation Example B1 are mixed and diluted according to the ratio of Example 1, and sprayed onto the surface of the cured polyurethane film, followed by heat treatment at 135°C. All other parameters are the same.

[0061] The purpose of this comparative example is to demonstrate that the interlayer adhesion generated by the "in-situ one-step method" of the present invention is far superior to that of the traditional "surface post-treatment method", and the process is simpler.

[0062] Experimental steps: Take 500g of each of the slurries prepared in Examples 1-5 and Comparative Examples 1-6, seal them, and place them in a constant temperature environment of 25℃. Use an NDJ-79 rotational viscometer to measure the viscosity of the slurries at the initial time (T0), after 1 hour (T1), after 24 hours (T2), and after 48 hours (T3). Record the flow state of the slurry during the test period. If the viscosity exceeds 20000 mPa·s or a non-flowing gel phenomenon occurs, it is recorded as gelation. The slurry that has not gelled after 48 hours of storage is coated, dried, and cured according to the process corresponding to each example. Observe the macroscopic morphology of the surface of the cured vegan leather under a D65 standard light source, and record the surface smoothness and the presence of defects such as shrinkage cavities, pinholes, or particulate matter.

[0063] Next, the following performance indicators were tested on the prepared vegan leather materials: Slurry stability test: As mentioned above, the viscosity change of the slurry at different time points was measured using an NDJ-79 rotational viscometer to observe whether there was gelation or stratification, thereby evaluating the storage stability of the latent curing system.

[0064] Surface hydrophobicity test: Static water contact angle (WCA): Using a contact angle meter (model: JC2000D), 5 μL of deionized water was added to the surface of the vegan leather sample at room temperature. After standing for 3 seconds, the contact angle value was read. Five different locations were selected for testing for each sample, and the average value was taken. The larger the contact angle, the better the hydrophobicity.

[0065] Water repellency rating: The test is conducted in accordance with GB / T4745-2012 "Test and evaluation of water-repellent properties of textiles - water repellency method" to evaluate the anti-wetting performance of the sample surface (level 1 is the worst, level 5 is the best).

[0066] Anti-mildew performance test: The test was conducted according to GB / T 24346-2009, "Evaluation of Anti-mildew Performance of Textiles". A mixed spore suspension of *Aspergillus niger*, *Chaetomium globosum*, and *Trichoderma viride* was sprayed onto the sample surface and incubated for 28 days in a constant temperature and humidity chamber at 28℃ and 90% relative humidity. Evaluation criteria: Grade 0: No mold was observed under a microscope; Level 1: Growth is visible, but the coverage area is <10%; Level 2: Coverage area 10%~30%; Level 3: Coverage area 30%~60%; Level 4: Coverage area > 60% (severe mold growth).

[0067] Abrasion resistance and functional durability testing (verification of anchoring effect): Using a Martindale abrasion tester, standard wool felt was used as the abrasive, and the sample surface was rubbed under a load of 12 kPa. The number of rubbing cycles was set to 10,000. After the rubbing was completed, the static water contact angle of the sample was tested again using the method described above.

[0068] The adhesion of functional components to the surface of vegan leather is evaluated by comparing the changes in contact angle before and after friction. A significant decrease in contact angle after friction indicates physical detachment of the functional layer; a high contact angle indicates effective anchoring of the metal-polyphenol network.

[0069] Results Analysis and Conclusions: Based on the above testing methods, the test results of each embodiment and comparative example are shown in Tables 1 and 2 below.

[0070] Table 1. Viscosity stability test results of slurries in each example and comparative example (unit: mPa·s)

[0071] Table 2. Performance test results of finished vegan leather in each embodiment and comparative example.

[0072] Detailed analysis based on the data in Tables 1 and 2: Slurry stability and pot life (verification of latent technology): As shown in Table 1, the viscosity of the slurries in Examples 1-5 increased slowly within 48 hours, and they maintained good fluidity throughout. This demonstrates that the use of volatile amine ligands (ethylenediamine, n-butylamine) to coordinate and shield metal ions effectively inhibits premature cross-linking of metal ions with plant polyphenols (tea / citrus extracts) or resins at room temperature.

[0073] Conversely, in Comparative Example 3, the direct addition of unprotected zinc acetate caused irreversible gelation of the slurry within 24 hours (T2 stage). This was because the highly active zinc ions instantly coordinated with the polyphenolic hydroxyl groups in the plant extract at multiple points, forming a three-dimensional cross-linked network, which made subsequent coating processing impossible.

[0074] Hydrophobicity and migration mechanism (verification of solvent gradient and support): The initial water contact angles of the example groups all exceeded 150°, achieving a superhydrophobic effect. In contrast to Example 1 and Comparative Example 4 (which used a low-boiling-point solvent, butanone), the contact angle of Comparative Example 4 was only 115.6°. This indicates that without the "pumping" effect of a high-boiling-point carrier solvent (such as DPM) during the programmed temperature rise process, the functional components cannot effectively migrate from the interior of the resin and accumulate on the surface, resulting in insufficient density of hydrophobic groups on the surface.

[0075] Abrasion resistance and mildew resistance (verification of MPN anchoring mechanism): Abrasion resistance: Example 1, after 10,000 wear cycles, showed a contact angle decrease of only about 8°, maintaining excellent hydrophobicity. In contrast, Comparative Example 2 (without metal crosslinking agent), while initially showing a high contact angle, rapidly decreased to 98.5° after wear, indicating that the functional layer lacking metal anchoring relies solely on physical adsorption and cannot effectively trap micron-sized biomass particles. After the friction experiment, Comparative Example 5 exhibited significant coffee grounds / filler detachment (powder shedding) on ​​its surface, resulting in a substantial decrease in contact angle. This demonstrates the mechanism of this invention—utilizing a metal and plant polyphenol network to in-situ encapsulate and anchor bio-waste particles—successfully addressing the industry pain point of easy wear and detachment of bio-based fillers in footwear applications.

[0076] Anti-mildew properties: All example groups achieved a level 0 anti-mold rating (no growth), attributed to the synergistic effect of metal ions (Zn / Fe) and natural active ingredients (such as EGCG and flavonoids) in tea residue / tangerine peel extract, constructing a dual biological and chemical antibacterial layer. Comparative Example 1 (blank) showed severe mold growth; Comparative Example 2, lacking the bactericidal efficacy and network locking of metal ions, showed mold growth in some areas (level 1); Comparative Example 5, lacking the key antibacterial component of plant polyphenols, achieved a level 3 anti-mold rating.

[0077] Process comparison (verifying the advantages of the one-step method): Comparative Example 6, using a traditional surface spraying process, showed acceptable initial performance, but the contact angle decreased to 110.5° after wear resistance, significantly lower than the 148.2° of Example 1. This demonstrates that the interlayer bonding force formed by in-situ migration and synchronous cross-linking in this invention is far stronger than the physical adhesion formed by traditional spraying, and the one-step process is simpler and more efficient.

[0078] In summary, this invention responds to the development trend of low-carbon and environmentally friendly bio-based materials, achieving high-value utilization of agricultural waste (tea / coffee / bagasse) through latent metal crosslinking technology. The resulting material not only possesses superhydrophobic and wear-resistant properties, but also solves the problems of limited functionality and poor durability of bio-based materials, demonstrating significant environmental benefits and commercial prospects.

[0079] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A self-hydrophobic and mildew-resistant modified leather material, characterized in that, It is made by coating, curing and bonding a modified polyurethane slurry to a base fabric; the modified polyurethane slurry is made from raw materials comprising the following parts by weight: 100.0 parts of a bio-based one-component polyurethane resin solution; Amphiphilic functional delivery carrier fluid 4.0-10.0 parts; 3.0-10.0 parts of biomass waste functional filler; 2.0-5.0 parts of latent metal crosslinking pre-formed solution; And organic solvents used to adjust viscosity.

2. The self-hydrophobic and mildew-resistant modified leather material according to claim 1, characterized in that, The latent metal crosslinking preform is prepared from raw materials including metal salts, volatile amine ligands, and alcohol solvents; The molar ratio of the metal salt to the volatile amine ligand is 1:(2.0-6.5).

3. The self-hydrophobic and mildew-resistant modified leather material according to claim 1, characterized in that, The amphiphilic functional delivery carrier fluid is prepared by dispersing raw materials including plant polyphenol extracts, side-chain amino-modified polysiloxanes, and high-boiling-point co-solvents. The mass ratio of the plant polyphenol extract, the side-chain amino-modified polysiloxane, and the high-boiling-point co-solvent is (1.0-2.0):(1.5-3.0):(3.0-5.0).

4. The self-hydrophobic and mildew-resistant modified leather material according to any one of claims 1-3, characterized in that, The specific selection of the raw materials includes: The solid content of the bio-based single-component polyurethane resin solution is 30% ± 2%; The biomass waste functional filler is selected from modified coffee grounds powder, sugarcane bagasse nanocellulose, or tea residue powder. The metal salt is selected from anhydrous zinc acetate or anhydrous ferric chloride; The volatile amine ligands are selected from ethylenediamine or n-butylamine; The plant polyphenol extract is selected from tea polyphenols, citrus peel extract or tannic acid; The high-boiling-point cosolvent is selected from dipropylene glycol methyl ether or ethylene glycol monobutyl ether, and its boiling point is higher than that of the volatile amine ligand.

5. The preparation process of the self-hydrophobic and mildew-resistant modified leather material according to claim 1, characterized in that, Includes the following steps: S1. Preparation of modified slurry: The amphiphilic functional transport carrier liquid is added to a single-component polyurethane resin solution and dispersed evenly. Then, the biomass waste functional filler is added and dispersed until there is no particulate matter. The latent metal crosslinking pre-prepared liquid is added, and an organic solvent is added to adjust the viscosity and degas to obtain the modified polyurethane slurry. S2. Coating: The modified polyurethane slurry obtained in step S1 is coated onto the patterned release paper to form a wet film; S3, Programmed temperature curing: The release paper coated with wet film in step S2 is heated and dried in stages. The solvent evaporation gradient induces the functional components to carry the biomass waste functional filler to the surface and undergo in-situ cross-linking and anchoring to form a cured film. S4. Post-processing: The cured film obtained in step S3 is bonded to the base fabric in a semi-molten state, and after curing, cooling and peeling off the release paper, the self-hydrophobic and mildew-resistant modified leather material is obtained.

6. The preparation process of the self-hydrophobic and mildew-resistant modified leather material according to claim 5, characterized in that, The preparation method of the latent metal crosslinking prepreg includes: The metal salt is dissolved in anhydrous ethanol, and a volatile amine ligand is added dropwise under stirring conditions at 5℃-30℃. After the addition is completed within 15-45 minutes, the mixture is sealed and stirred to obtain a clear and transparent or colored transparent liquid.

7. The preparation process of the self-hydrophobic and mildew-resistant modified leather material according to claim 5, characterized in that, The preparation method of the amphiphilic functional delivery carrier fluid includes: Plant polyphenol extracts were dissolved in a high-boiling-point co-solvent heated to 40-50℃, and then side-chain amino-modified polysiloxanes were added. The mixture was then dispersed using a high-speed disperser to obtain a homogeneous liquid.

8. The preparation process of the self-hydrophobic and mildew-resistant modified leather material according to claim 5, characterized in that, The programmed temperature curing in step S3 specifically involves passing the release paper coated with the wet film in step S2 through two drying stages sequentially: First drying stage: The first heating temperature is set to 65-90℃, and the residence time is 2-4 minutes. The first heating temperature is set to be lower than the boiling point of the volatile amine ligand, so as to prevent the release of metal ions while inducing the amphiphilic functional transport carrier liquid and biomass waste functional filler to migrate and accumulate to the wet film surface by utilizing the solvent evaporation gradient. Second drying stage: The second heating temperature is set to 120-150℃, and the residence time is 2-3 minutes. The second heating temperature is set to be higher than the boiling point of the volatile amine ligand, so as to promote the volatilization of the volatile amine ligand and release the coordination shielding of the metal ions, thereby initiating in-situ crosslinking between the metal ions and the polyphenol compound.

9. The preparation process of the self-hydrophobic and mildew-resistant modified leather material according to claim 5, characterized in that, In step S2, the viscosity of the modified polyurethane slurry is controlled at 2500-4000 mPa·s, and the thickness of the wet film is 100-150 μm.

10. The self-hydrophobic and mildew-resistant modified leather material according to claim 1, characterized in that, It is used in the preparation of shoe upper materials, shoe lining materials or insole fabrics to improve the surface stain resistance and antifungal growth ability of footwear products in humid environments.

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