Protein bionic structure enhanced wear-resistant leather and preparation method thereof

Abstract

The invention relates to the technical field of leather materials, and particularly discloses wear-resistant leather with an enhanced protein bionic structure and a preparation method of the wear-resistant leather. The wear-resistant leather sequentially comprises a multi-stage bionic wear-resistant surface layer, a protein bionic core layer and base cloth from top to bottom, pangolin scale macroscopic ribs and sharkskin microcosmic grooves are re-carved on the multi-stage bionic wear-resistant surface layer, and a nano hard-phase filler is compounded; the protein bionic core layer adopts a spider silk multistage fiber structure and a shell hard phase embedding mechanism, and a dynamic cross-linked network is introduced; and the transition layer and the dynamic cross-linking bonding layer realize interlayer stable combination and micro-damage self-repairing. The preparation method comprises the steps of raw material pretreatment, raw material preparation of each layer, step-by-step forming, composite curing and the like. Through multistage collaborative bionic and dynamic crosslinking design, the problems that traditional protein-based leather is poor in wear resistance and insufficient in long-term effect are solved, meanwhile, the skin-friendly and environment-friendly advantages are reserved, the wear resistance, the tearing strength and the interlayer binding force are remarkably improved, and the protein-based leather is suitable for high-end shoes, automobile interiors and other scenes.

Description

Technical Field

[0001] This invention relates to the field of leather materials technology, specifically to a wear-resistant leather reinforced with a protein biomimetic structure and its preparation method. Background Technology

[0002] With the increasing awareness of environmental protection and the upgrading of consumer demand, traditional synthetic leather (PU / PVC) is gradually being limited due to its poor environmental performance and lack of skin-friendliness. Meanwhile, protein-based leather (made from collagen, silk fibroin, etc.) has become an important development direction for leather materials due to its natural advantages of being skin-friendly, breathable, and biodegradable.

[0003] However, protein-based leather faces similar technical bottlenecks to traditional silicone leather: protein molecules tend to form low-density network structures during cross-linking, resulting in low tear strength and poor abrasion resistance. Long-term use can lead to cracking and wear, making it difficult to meet the abrasion resistance requirements of furniture, footwear, and automotive interiors. Current technologies for improving the abrasion resistance of protein-based leather mainly involve adding inorganic fillers (such as silica and calcium carbonate) or composite synthetic resins. However, these methods often reduce the leather's flexibility and skin-friendliness, and do not address the long-term durability issue after wear.

[0004] While silicone leather possesses excellent weather resistance and solvent resistance, it lacks the skin-friendly and breathable properties of protein materials and does not incorporate biomimetic structural design or self-healing functions, thus failing to meet the dual requirements of "wear resistance" and "long-lasting use." PU / PVC synthetic leather, on the other hand, suffers from inherent defects such as insufficient environmental friendliness and poor weather resistance, making it difficult to meet the requirements of the high-end market for green materials.

[0005] Therefore, there is an urgent need to develop a leather material that can integrate the triple advantages of "skin-friendly and environmentally friendly, highly wear-resistant, and long-lasting stability". Through innovative structural design and preparation process, it is necessary to solve the industry pain points of "poor wear resistance and easy aging" of traditional protein-based leather and "not environmentally friendly and not skin-friendly" of synthetic leather. Summary of the Invention

[0006] The purpose of this invention is to provide a wear-resistant leather with enhanced protein biomimetic structure and its preparation method, so as to solve the problems of "poor wear resistance and easy aging" of existing traditional protein-based leather and "not environmentally friendly and not skin-friendly" of synthetic leather.

[0007] The technical solution of the present invention to solve the above-mentioned technical problems is as follows: The protein biomimetic structure-enhanced abrasion-resistant leather of the present invention comprises, from top to bottom, a multi-level biomimetic abrasion-resistant surface layer, a protein biomimetic core layer, a transition layer, a dynamic cross-linking adhesive layer, and a base fabric. Each layer has a clear functional division and works synergistically to form a full-chain protection system of "friction reduction, tear resistance, abrasion resistance, self-repair, and interlayer stabilization." Multi-level biomimetic wear-resistant surface layer: As a direct friction interface, it achieves a core improvement in wear resistance through a triple design of "macro-scale ridges to disperse stress + micro-grooves to reduce friction + nano-hard phase to enhance hardness"; Protein biomimetic core layer: As a support layer, it provides high tear strength and flexibility through a multi-level fiber structure and hard phase embedding mechanism, avoiding rapid failure of the core structure after surface wear; Transition layer: Eliminates structural abrupt changes between the surface and core layers, and achieves mechanical anchoring and chemical bonding through interpenetrating networks to enhance interlayer synergy; Dynamic cross-linked adhesive layer: achieves a stable connection between the core layer and the base fabric, while also providing interlayer micro-peeling self-healing capability; Base fabric: Provides overall structural support, enhancing the stiffness and stability of the leather.

[0008] Raw material formulas and functions of each layer Multi-level biomimetic wear-resistant surface layer (parts by weight): 30-40 parts silk fibroin: as a surface matrix, providing flexibility and skin-friendliness; Dopamine-modified nano-silicon nitride 3-5 parts (particle size 50-100nm): Dopamine modification improves compatibility with protein matrix, and nano-silicon nitride enhances surface hardness and wear resistance. Hyaluronic acid 0.8-1.2 parts: provides self-repair ability for surface micro-scratches, filling tiny damages through hydrogen bond recombination; Polydopamine 0.5-1 part: enhances the interfacial bonding force of surface raw materials and improves structural stability; KH-560 silane coupling agent 1-2 parts: promotes the synergistic effect between inorganic fillers and organic matrix, and avoids filler agglomeration.

[0009] Protein biomimetic core layer (parts by weight): 50-60 parts collagen + 20-30 parts silk fibroin: form a complex protein matrix that balances skin affinity and mechanical properties; 5-8 parts of cellulose nanocrystals: mimicking spider silk nanofibers, forming the core unit for constructing a multi-level fiber structure; Dopamine-modified nano-hydroxyapatite 3-5 parts (particle size 50-200nm): mimics hard phase particles of seashells, embedded in fiber gaps to enhance wear resistance and tear resistance; Genipin 2-3 servings+ 0.5-1 part of ions: composite crosslinking agent, adjusting the degree of crosslinking to 40%-45%, balancing mechanical strength and flexibility; Cystamine 1-2 parts: provides disulfide bonds, forming a dual cross-linking network with proteins: Schiff base bond (static strength) - disulfide bond (dynamic repair).

[0010] Transition layer (parts by weight): 50 parts silk fibroin + 20 parts chitosan: form a protein-polysaccharide complex matrix that is compatible with the material properties of the surface and core layers; 10 portions of dopamine-modified cellulose nanocrystals: one end is embedded in the fiber gaps of the core layer to form a mechanical anchor, and the other end forms a chemical bond with the surface layer; 1 part of KH-560 silane coupling agent: to enhance the structural stability of interpenetrating networks.

[0011] Dynamic cross-linked adhesive layer (parts by weight): Dopamine-modified collagen 30-40 parts: achieves strong adhesion through the catechol groups of dopamine; 10-15 parts chitosan + 10-15 parts waterborne polyurethane: Improves the water resistance and mechanical stability of the adhesive layer; 0.5-1 part of polyethylene glycol containing disulfide bonds (PEG-SS-PEG, number average molecular weight 2000-4000): introduces a dynamic cross-linking network to achieve self-repair of interlayer micro-exfoliation; KH-560 silane coupling agent 1-2 parts: enhances the interfacial bonding force with the base fabric.

[0012] Base fabric: Use 0.3-0.5mm thick non-woven fabric or natural leather base to provide structural support and user comfort.

[0013] The specific preparation steps for protein-inspired biomimetic structure-enhanced abrasion-resistant leather are as follows: Raw material pretreatment: Collagen and silk fibroin were dissolved in deionized water to prepare an aqueous solution with a mass fraction of 10%-15%, which was then refrigerated at 4°C for later use to avoid protein denaturation. Nano-silicon nitride, nano-hydroxyapatite, and cellulose nanocrystals were modified with dopamine. The specific method was as follows: the nanoparticles were dispersed in deionized water, dopamine hydrochloride (concentration 0.5mg / mL) was added, the pH was adjusted to 8.5, stirred at room temperature for 24h, and then centrifuged and dried for later use to improve compatibility with the protein matrix.

[0014] Surface material preparation: Mix silk fibroin, dopamine-modified nano-silicon nitride, hyaluronic acid, polydopamine, and KH-560 silane coupling agent according to the weight proportions, put them into a planetary dispersion mixer, and use 20-30℃ cooling water to control the stirring speed at 800-1200 rpm and the vacuum degree ≤-0.09MPa. Disperse and stir for 15-20 minutes to ensure that the system is uniform and free of bubbles, and obtain the surface material.

[0015] Core layer ingredient formulation: Collagen, silk fibroin, cellulose nanocrystals, dopamine-modified nano-hydroxyapatite, genipin, etc., are mixed in parts by weight. Ions and cystamine are stirred for 10-15 minutes under the same equipment and vacuum conditions to obtain the core layer raw material.

[0016] Preparation of transition layer and adhesive layer raw materials: Mix the transition layer and dynamic cross-linked adhesive layer raw materials according to the formula, and stir each under vacuum for 15 minutes to obtain the transition layer raw material and adhesive layer raw material.

[0017] Surface forming: The surface material is coated onto the release paper, and the pangolin scale-like rhomboid macroscopic ridges are pressed through a 3D mold (pressing pressure 0.3-0.5MPa). Then, the shark skin-like micro grooves are replicated by laser micro-nano imprinting (laser power 5-10W). The surface is then baked in an oven at 60-70℃ for 3-5 minutes to form a multi-level biomimetic wear-resistant surface.

[0018] Core layer composite: The core layer material is uniformly coated on the surface and then subjected to directional freeze stretching (gradual heating from -20℃ to 0℃, stretching rate of 5mm / min, and total stretching amount of 1.5-2 times the length of the material). Then, it is cured by gradient heating in a vacuum environment (60℃ for 3min → 70℃ for 3min → 80℃ for 2min) to form a protein biomimetic core layer with a nanofiber orientation degree of ≥95%.

[0019] Transition layer and adhesive layer composite: The transition layer material and adhesive layer material are coated sequentially on the surface of the core layer. After each coating, the layers are baked at 65-75℃ for 3-4 minutes. Finally, the layers are bonded to the base fabric and baked at 70℃ for 8-10 minutes to ensure full bonding between the layers.

[0020] Post-processing: Peel off the release paper and let it stand at room temperature (50%-60% relative humidity) for 24 hours to activate the dynamic cross-linking network and obtain abrasion-resistant leather with protein biomimetic structure enhancement.

[0021] The present invention has the following beneficial effects: This invention effectively improves the tear strength of the silicone rubber layer by precisely optimizing the hardness of the liquid adhesive, providing a solid structural support for the silicone leather. At the same time, a wear-resistant layer containing specific fillers is set on the surface of the silicone rubber layer, further enhancing the wear resistance of the leather surface, forming a dual protection system of "strong core layer support + targeted wear resistance of the surface layer".

[0022] By rationally designing the layered structure of the wear-resistant layer, silicone rubber layer, and adhesive layer, and by using appropriate raw material formulations and precisely controlled preparation processes, the bonding between each layer is ensured to be stable, thus avoiding the problem of wear resistance failure due to delamination between layers during use.

[0023] While retaining the original advantages of silicone leather, such as heat resistance, stain resistance, solvent resistance, hydrolysis resistance, and weather resistance, this invention successfully overcomes its shortcomings in abrasion resistance, significantly improving the overall performance of silicone leather and enabling it to better meet the usage requirements of various fields such as furniture, decoration, clothing, footwear, and automobiles. Attached Figure Description

[0024] Figure 1 The diagram illustrates the specific steps of the method of the present invention.

[0025] Figure 2 This is a schematic diagram of the structure of the leather of the present invention.

[0026] In the figure: multi-level biomimetic wear-resistant surface layer 100, protein biomimetic core layer 200, transition layer 300, dynamic cross-linking adhesive layer 400 and base fabric 500. Detailed Implementation

[0027] The principles and features of the present invention are described below with reference to the accompanying drawings. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention. Example 1

[0028] Raw material formulas for each layer (parts by weight): Multi-level biomimetic wear-resistant surface layer: 35 parts silk fibroin, 4 parts dopamine-modified nano-silicon nitride (particle size 80nm), 1.0 part hyaluronic acid, 0.8 parts polydopamine, and 1.5 parts KH-560 silane coupling agent; Protein biomimetic core layer: 55 parts collagen, 25 parts silk fibroin, 6 parts cellulose nanocrystals, 4 parts dopamine-modified nano-hydroxyapatite (100nm particle size), 2.5 parts genipin. 0.8 parts of ions, 1.5 parts of cystamine; Transition layer: 50 parts silk fibroin, 20 parts chitosan, 10 parts dopamine-modified cellulose nanocrystals, and 1 part KH-560 silane coupling agent; Dynamic cross-linked adhesive layer: 35 parts dopamine-modified collagen, 12 parts chitosan, 12 parts waterborne polyurethane, 0.8 parts PEG-SS-PEG (number average molecular weight 3000), and 1.5 parts KH-560 silane coupling agent; Base fabric: 0.4mm thick non-woven fabric.

[0029] Thickness of each layer: multi-level biomimetic wear-resistant surface layer 0.08mm, protein biomimetic core layer 0.15mm, transition layer 0.04mm, dynamic cross-linking adhesive layer 0.08mm.

[0030] Preparation steps: Raw material pretreatment: Collagen and silk fibroin were prepared into a 12% aqueous solution and refrigerated at 4℃; nanofillers were treated with dopamine modification method for later use; Surface material preparation: planetary dispersion mixer (speed 1000 rpm, vacuum degree -0.1 MPa), through 25℃ cooling water, stir for 18 minutes; Core layer raw material preparation: Under the same equipment conditions, stir for 12 minutes; Preparation of raw materials for transition layer and adhesive layer: each is vacuum stirred for 15 minutes; Surface forming: 3D mold pressing pressure 0.4MPa, laser power 8W, 65℃ baking for 4 minutes; Core layer composite: directional freeze stretching with a total stretch of 1.8 times, vacuum gradient curing (60℃ 3min→70℃ 3min→80℃ 2min). Transition layer and adhesive layer lamination: Each layer is baked at 70℃ for 3.5 minutes after coating, and the base fabric is baked at 70℃ for 9 minutes after lamination; Post-processing: Let stand at room temperature (55% humidity) for 24 hours to obtain the finished product. Example 2

[0031] The difference from Example 1 is as follows: Multi-level biomimetic wear-resistant surface layer: 30 parts silk fibroin, 3 parts dopamine-modified nano-silicon nitride (particle size 50nm), 0.8 parts hyaluronic acid, 0.5 parts polydopamine, and 1 part KH-560 silane coupling agent; Protein biomimetic core layer: 50 parts collagen, 20 parts silk fibroin, 5 parts cellulose nanocrystals, 3 parts dopamine-modified nano-hydroxyapatite (50nm particle size), 2 parts genipin 0.5 parts of ions, 1 part of cystamine; Dynamic cross-linked adhesive layer: PEG-SS-PEG number average molecular weight 2000, dosage 0.5 parts; Thickness of each layer: surface layer 0.05mm, core layer 0.1mm, transition layer 0.03mm, adhesive layer 0.05mm; Preparation steps: Surface layer is baked at 60℃ for 5 minutes, and the core layer is stretched by 1.5 times. Example 3

[0032] The difference from Example 1 is as follows: Multi-level biomimetic wear-resistant surface layer: 40 parts silk fibroin, 5 parts dopamine-modified nano-silicon nitride (particle size 100nm), 1.2 parts hyaluronic acid, 1 part polydopamine, and 2 parts KH-560 silane coupling agent; Protein biomimetic core layer: 60 parts collagen, 30 parts silk fibroin, 8 parts cellulose nanocrystals, 5 parts dopamine-modified nano-hydroxyapatite (particle size 200nm), 3 parts genipin 1 part ion, 2 parts cystamine; Dynamic cross-linked adhesive layer: PEG-SS-PEG number average molecular weight 4000, 1 part; Thickness of each layer: surface layer 0.1mm, core layer 0.2mm, transition layer 0.05mm, adhesive layer 0.1mm; Preparation steps: Surface layer is baked at 70℃ for 3 minutes, and the core layer is stretched by 2 times. Comparative Example 1

[0033] The difference from Example 1 is that the multi-level biomimetic wear-resistant surface layer does not contain dopamine-modified nano-silicon nitride, while the other raw materials and process parameters are the same. Comparative Example 2

[0034] The difference from Example 1 is that cystamine was not added to the protein biomimetic core layer (no dynamic cross-linking network), while the other raw materials and process parameters were the same.

[0035] Comparative Example 3 The difference from Example 1 is that no transition layer is set, and the other raw materials and process parameters are the same.

[0036] Performance testing The leather samples from Examples 1 to 3 and Comparative Examples 1 to 3 were subjected to performance tests. The test standards and results are as follows:

[0037] Test results show that the leather samples of Examples 1 to 3 of this invention exhibit excellent performance in abrasion resistance, tear strength, interlayer bonding force, and self-repair efficiency. In contrast, Comparative Example 1 (lacking nano hard phase filler) shows a significant decrease in abrasion resistance, Comparative Example 2 (without dynamic cross-linking network) has almost no self-repair ability, and Comparative Example 3 (without transition layer) shows a significant reduction in interlayer peel strength. This fully demonstrates the technical advantages of the multi-level biomimetic structure, dynamic cross-linking network, and interlayer synergistic design of this invention.

[0038] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A type of abrasion-resistant leather reinforced with a protein biomimetic structure, characterized in that, From top to bottom, it includes a multi-level biomimetic wear-resistant surface layer (100), a protein biomimetic core layer (200), a transition layer (300), a dynamic cross-linking adhesive layer (400), and a base fabric (500). The multi-level biomimetic wear-resistant surface layer (100) is made of the following raw materials in parts by weight: 30-40 parts silk fibroin, 3-5 parts dopamine-modified nano-silicon nitride, 0.8-1.2 parts hyaluronic acid, 0.5-1 parts polydopamine, and 1-2 parts KH-560 silane coupling agent. The multi-level biomimetic wear-resistant surface layer (100) replicates the macroscopic ridges of pangolin scales and the microscopic grooves of shark skin. The nano-silicon nitride is uniformly dispersed in the surface matrix. The protein biomimetic core layer (200) is made from the following raw materials in parts by weight: 50-60 parts collagen, 20-30 parts silk fibroin, 5-8 parts cellulose nanocrystals, 3-5 parts dopamine-modified nano-hydroxyapatite, and 2-3 parts genipin. The protein biomimetic core layer (200) is a multi-level orientation structure of "macrofiber bundle-microfiber-nanofibers" with a cross-linking degree of 40%-45%; the transition layer (300) is made of the following raw materials in parts by weight: 50 parts silk fibroin, 20 parts chitosan, 10 parts dopamine-modified cellulose nanocrystals, and 1 part KH-560 silane coupling agent, forming a protein-polysaccharide-nanofibers interpenetrating network; The dynamic cross-linked adhesive layer (400) is made of the following raw materials in parts by weight: 30-40 parts of dopamine-modified collagen, 10-15 parts of chitosan, 10-15 parts of waterborne polyurethane, 0.5-1 parts of polyethylene glycol containing disulfide bonds, and 1-2 parts of KH-560 silane coupling agent. The thickness range of each layer is as follows: multi-level biomimetic wear-resistant surface layer 0.05-0.1mm, protein biomimetic core layer 0.1-0.2mm, transition layer 0.03-0.05mm, dynamic cross-linking adhesive layer 0.05-0.1mm, base fabric (500) 0.3-0.5mm.

2. The protein biomimetic structure-enhanced abrasion-resistant leather according to claim 1, characterized in that, The particle size of the dopamine-modified nano-silicon nitride is 50-100nm, and the particle size of the dopamine-modified nano-hydroxyapatite is 50-200nm; the base fabric (500) is a non-woven fabric or a natural leather base.

3. The protein biomimetic structure-enhanced abrasion-resistant leather according to claim 1, characterized in that, The macroscopic ridges are rhomboid in shape, with a height of 50-80 μm and a spacing of 200-300 μm; the microscopic grooves are 30-50 μm wide and 10-15 μm deep.

4. The protein biomimetic structure-enhanced abrasion-resistant leather according to claim 1, characterized in that, In the multi-level orientation structure of the protein biomimetic core layer, the orientation degree of the nanofibrils is ≥95%; the cystamine provides disulfide bonds, forming a "Schiff base bond-disulfide bond" double cross-linking network with the protein.

5. A method for preparing abrasion-resistant leather with a protein biomimetic structure enhancement, characterized in that, Includes the following steps: S1: Raw material pretreatment: Collagen and silk fibroin are dissolved in deionized water to prepare an aqueous solution with a mass fraction of 10%-15%, which is then refrigerated at 4℃ for later use; Nano silicon nitride, nano hydroxyapatite, and cellulose nanocrystals are modified with dopamine. S2: Surface material preparation: Mix silk fibroin, dopamine-modified nano-silicon nitride, hyaluronic acid, polydopamine, and KH-560 silane coupling agent according to the target weight proportions, put them into a planetary dispersion mixer, and stir under vacuum for 15-20 minutes with 20-30℃ cooling water to obtain the surface material. S3: Core Layer Raw Material Formulation: Mix collagen, silk fibroin, cellulose nanocrystals, dopamine-modified nano-hydroxyapatite, and genipin according to the target weight proportions. Ions and cystamine are vacuum stirred for 10-15 minutes to obtain the core layer raw material. S4: Preparation of transition layer and adhesive layer raw materials: Mix the transition layer and dynamically cross-linked adhesive layer raw materials according to the target formula, and stir each under vacuum for 15 minutes to obtain the transition layer raw material and adhesive layer raw material; S5: Surface forming: The surface material is coated onto the release paper, macroscopic ridges are pressed by 3D mold, micro grooves are then imprinted by laser micro-nano imprinting, and baked at 60-70℃ for 3-5 minutes to form a multi-level biomimetic wear-resistant surface layer. S6: Core layer composite: The core layer material is coated on the surface layer, and after directional freeze stretching (-20℃→0℃ gradient temperature increase, stretching rate 5mm / min), it is cured by gradient temperature increase (60℃ 3min→70℃ 3min→80℃ 2min) to form a protein biomimetic core layer. S7: Transition layer and adhesive layer composite: The transition layer material and adhesive layer material are coated sequentially on the surface of the core layer. After each layer is coated, it is baked at 65-75℃ for 3-4 minutes. Finally, it is bonded to the base fabric and baked at 70℃ for 8-10 minutes. S7: Post-treatment: Peel off the release paper, let stand at room temperature for 24 hours to activate the dynamic cross-linking network, and obtain abrasion-resistant leather with protein biomimetic structure enhancement.

6. The method for preparing protein biomimetic structure-enhanced abrasion-resistant leather according to claim 5, characterized in that, In step S5, the 3D mold pressing pressure is 0.3-0.5MPa, and the laser power of laser micro-nano imprinting is 5-10W.

7. The method for preparing protein biomimetic structure-enhanced abrasion-resistant leather according to claim 5, characterized in that, In step S6, the total stretching amount of directional freeze stretching is 1.5-2 times the length of the raw material, and a vacuum environment is maintained during the gradient temperature curing process.

8. The method for preparing protein biomimetic structure-enhanced abrasion-resistant leather according to claim 5, characterized in that, In steps S2, S3, and S4, the stirring speed of the planetary dispersion mixer is 800-1200 rpm, and the vacuum degree is ≤-0.09 MPa.

9. The method for preparing abrasion-resistant leather with protein biomimetic structure enhancement according to claim 5, characterized in that, The polyethylene glycol containing disulfide bonds in the dynamic cross-linked adhesive layer is PEG-SS-PEG with a number average molecular weight of 2000-4000.

10. The method for preparing abrasion-resistant leather with protein biomimetic structure enhancement according to claim 5, characterized in that, In step S7, the relative humidity of the room temperature static environment is 50%-60% to ensure that the dynamic cross-linking network is fully activated.

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