Composite leather material and preparation method thereof

Abstract

The embodiment of the invention provides a composite leather material and a preparation method thereof, the material is composed of an aluminum foil layer, a carbon fiber reinforced PVC layer, and a silicon-dendritic polymer-silver nanoparticle xerogel antibacterial and antiviral coating, and can be coated with a BAC layer. 75HV type PVC is used as a base material of the PVC layer, 4mm and 10phr short carbon fibers are added, the PVC layer is subjected to hot-pressing compounding with aluminum foil after banburying and film casting, the antibacterial coating is prepared from orthosilicic acid and silver nanoparticle / PEI composite solution and is coated twice, and the process and performance rationality are proved by attached drawings. The tensile strength of the material is 48.9 MPa, the tear strength is 14.7 kN / m, the VOC emission is 3.975 mg / m, the antibacterial and antiviral performance is excellent, compared with a common PVC foil, the mechanical and test accuracy and the environmental protection property are remarkably improved, migration test traces are clear, and the material is suitable for color migration test scenes of leather quality detection.

Description

Technical Field

[0001] This invention relates to the field of leather composite materials technology, specifically to a composite leather material and its preparation method that combines high barrier properties, high mechanical properties, low VOC emissions, and antibacterial and antiviral functions. Background Technology

[0002] In leather product quality testing, "color migration from leather to PVC" is a key indicator, directly reflecting the compatibility between leather and PVC materials. Currently, most materials used for this test are ordinary PVC foils. While these meet basic testing requirements, they have significant drawbacks: First, their mechanical properties are insufficient, making them prone to breakage due to contact and compression during testing, affecting accuracy. Second, they lack barrier and shielding properties, failing to effectively prevent moisture and external interference, potentially indirectly affecting dye migration. Third, they lack antibacterial and antiviral functions; prolonged contact between leather and PVC foil during testing can easily breed bacteria, contaminating the testing environment. Fourth, ordinary PVC foils have high VOC emissions, failing to meet environmental testing requirements.

[0003] Meanwhile, while existing PVC-coated aluminum foil materials possess flexibility, barrier properties, and shielding capabilities (moisture resistance, electromagnetic interference protection, etc.), they are not optimized for leather color migration testing and lack mechanical reinforcement, antibacterial, and antiviral functions, failing to meet the demands of high-precision and environmentally friendly testing. Therefore, developing a PVC-coated aluminum foil composite leather material for ISO 15701 / IUF 442 standard testing, possessing high barrier properties, high mechanical strength, low VOCs, and antibacterial and antiviral functions, is key to addressing the aforementioned technical challenges. This invention proposes a composite leather material and its preparation method to at least partially solve the problems existing in the prior art. Therefore, this invention proposes a composite leather material and its preparation method to at least partially solve the potential problems existing in the prior art. Summary of the Invention

[0004] In view of the above problems, a composite leather material and its preparation method are proposed to overcome or at least partially solve the above problems.

[0005] A composite leather material, from bottom to top, comprises an aluminum foil layer, a PVC reinforcement layer, and an antibacterial and antiviral coating; The PVC reinforcement layer uses 75HV type PVC resin as the base material and adds short carbon fibers; The antibacterial and antiviral coating is a silicon-dendritic polymer-silver nanoparticle composite dry gel coating. The composite leather material is used for the "color migration from leather to PVC" test according to ISO 15701 / IUF 442 standard. During the test, the silver protective film on the surface of the aluminum foil layer is removed, so that the PVC reinforcement layer is in direct contact with the leather sample.

[0006] Optionally, the raw material formulation of the PVC reinforcement layer, based on 100 phr of PVC resin, includes: 75HV type PVC resin 100 phr, plasticizer DPHP 65 phr, heat stabilizer Stab5 1 phr, processing aid PA-40 1 phr, short carbon fiber 10 phr; The short carbon fiber has a length of 4 mm.

[0007] Optionally, the antibacterial and antiviral coating is prepared by mixing a silica solution and a silver nanoparticle / PEI composite solution at a volume ratio of 1:1; the molecular weight of PEI is 750,000; the silver nanoparticle / PEI composite solution is prepared by mixing a PEI solution and a 0.1M silver nitrate solution at a volume ratio of 4:1 and allowing it to stand at room temperature in the dark for 8 days.

[0008] Optionally, the aluminum foil layer has a thickness of 0.05 mm and a removable silver protective film on its surface; The aluminum foil layer and the PVC reinforcement layer are fixed together by hot pressing.

[0009] Optionally, the surface of the antibacterial and antiviral coating is further coated with a BAC layer; The BAC layer is made by coating with a 50% concentration BAC solution at a coating amount of 100 μL / cm²; the BAC is benzyl dimethyl ammonium chloride.

[0010] Optionally, the thickness of the PVC reinforcement layer is 0.3 mm; the total thickness of the antibacterial and antiviral coating is 0.2 mm, formed by two coatings.

[0011] In some embodiments of this application, a method for preparing a composite leather material is also disclosed, comprising the following steps: (1) Preparation of PVC reinforcement layer: 75HV type PVC resin, plasticizer DPHP, heat stabilizer Stab5, processing aid PA-40 and short carbon fiber are mixed, and then mixed and cast into a film to obtain PVC reinforcement layer; (2) Preparation of PVC aluminum foil substrate: The aluminum foil and the PVC reinforcing layer are hot-pressed together to obtain PVC aluminum foil substrate; (3) Preparation of antibacterial and antiviral coating precursor solution: Tetraethyl orthosilicate is hydrolyzed with nitric acid to obtain orthosilicic acid solution, which is then mixed with silver nanoparticle / PEI composite solution and the pH is adjusted to 7.5 to obtain precursor solution; (4) Applying an antibacterial and antiviral coating: The precursor liquid is applied to the surface of the PVC reinforcement layer, and after drying, the coating is repeated once to form an antibacterial and antiviral coating. (5) Optional step: Coat the surface of the antibacterial and antiviral coating with BAC solution, and obtain the BAC layer after drying; (6) Finished product processing: Cut the composite material to the required size for testing and set aside.

[0012] Optionally, the mixing conditions in step (1) are: mixing at 150°C for 15 min, front roller speed of 15 r / min, and rear paddle speed of 10 r / min; the thickness of the cast film is controlled to be 0.3 mm.

[0013] Optionally, the hot-pressing composite conditions in step (2) are: hot pressing at 120℃ and 0.5 MPa for 30 s; the aluminum foil surface is pre-deposited with a silver protective film, and the protective film faces away from the PVC reinforcement layer during hot pressing.

[0014] Optionally, in step (4), the drying conditions are drying overnight in an oven at 60°C; in step (5), after coating with BAC solution, the solution is dried at 60°C for 12 h.

[0015] The embodiments of the present invention have the following advantages: By combining the flexibility of PVC with the barrier and shielding properties (moisture-proof and electromagnetic interference-proof) of aluminum foil with the PVC-coated aluminum foil substrate, the PVC base film can effectively contact leather samples after the silver protective film is removed, accurately detecting the migration of leather dyes into PVC, fully complying with ISO 15701 / IUF 442 standards. The reinforcement of short carbon fibers increases the tensile strength of the PVC base film by 50% and the tear strength by 29%, making it less prone to breakage during testing and ensuring test stability. Carbon fibers restrict the movement of PVC molecular chains, enhancing thermal stability and reducing total VOC emissions to 3.975 mg / m³, meeting environmental testing requirements. The dry gel coating achieves an inhibition rate of over 97% against bacteria such as Escherichia coli and Staphylococcus aureus, and reduces the SARS-CoV-2 virus titer by 10 times, preventing bacterial growth and contamination of test samples and the environment during testing. The aluminum foil layer effectively prevents moisture and isolates external interference, avoiding environmental factors from affecting dye migration and improving the accuracy of test results. Attached Figure Description

[0016] To more clearly illustrate the technical solution of the present invention, the accompanying drawings used in the description of the present invention will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a flowchart illustrating the preparation of carbon fiber reinforced PVC foam, a method for preparing composite leather material according to some embodiments of the present invention. Figure 2These are SEM images of different PVC foams of a composite leather material and its preparation method provided in some embodiments of the present invention; Figure 3 This is a SEM image of a composite dry gel coating of a composite leather material and its preparation method provided in some embodiments of the present invention; Figure 4 These are energy dispersive X-ray spectra of untreated leather provided in some embodiments of the present invention; Figure 5 These are energy dispersive X-ray spectra of leather wetted with PEI-AgNPs solution provided in some embodiments of the present invention; Figure 6 These are energy dispersive X-ray spectra of leather coated with silica-PEI-Ag NPs composite dry gel according to some embodiments of the present invention; Figure 7 These are energy dispersive X-ray spectra of leather coated with composite dry gel provided in some embodiments of the present invention; Figure 8 This is a diagram showing the effect of carbon fiber length and content on mechanical properties provided in some embodiments of the present invention. Detailed Implementation

[0018] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0019] This invention provides a composite leather material in some embodiments, comprising: a PVC-coated aluminum foil as the core substrate, combined with carbon fiber reinforcement and a silicon-dendritic polymer-silver nanoparticle composite dry gel coating, achieving synergy between testing functions and additional properties. The specific scheme is as follows: from bottom to top, it includes an aluminum foil layer, a PVC reinforcement layer, and an antibacterial and antiviral coating; the PVC reinforcement layer uses 75HV type PVC resin as the substrate, with added short carbon fibers; the antibacterial and antiviral coating is a silicon-dendritic polymer-silver nanoparticle composite dry gel coating; the composite leather material is used for the "color migration from leather to PVC" test according to the ISO 15701 / IUF 442 standard. During the test, the silver protective film on the surface of the aluminum foil layer is removed, allowing the PVC reinforcement layer to directly contact the leather sample. The PVC reinforcement layer retains the flexibility of PVC, and the aluminum foil layer provides moisture resistance, electromagnetic interference prevention, and shielding, effectively avoiding environmental factors interfering with dye migration. The accuracy of the test results is improved by more than 30% compared to ordinary PVC foil sheets, fully meeting the requirements of the ISO 15701 / IUF 442 standard.

[0020] Furthermore, the raw material formulation of the PVC reinforcing layer, based on 100 phr of PVC resin, includes: 100 phr of 75HV type PVC resin, 65 phr of plasticizer DPHP, 1 phr of heat stabilizer Stab5, 1 phr of processing aid PA-40, and 10 phr of short carbon fibers; the length of the short carbon fibers is 4 mm. The reinforcing effect of the 4 mm short carbon fibers enables the PVC reinforcing layer to achieve a tensile strength of 48.9 MPa (50% higher than ordinary PVC foil) and a tear strength of 14.7 kN / m (29% higher), with no breakage during testing, and stability improved by 40% compared to existing materials. The carbon fibers restrict the movement of PVC molecular chains, enhance thermal stability, and reduce the total VOC emissions to 3.975 mg / m³, a 28% reduction compared to ordinary PVC foil (5.505 mg / m³), meeting environmental testing requirements.

[0021] The antibacterial and antiviral coating is prepared by mixing a silicate solution and a silver nanoparticle / PEI composite solution at a volume ratio of 1:1; the molecular weight of PEI is 750,000; the silver nanoparticle / PEI composite solution is prepared by mixing PEI solution and 0.1 M silver nitrate solution at a volume ratio of 4:1 and allowing it to stand at room temperature in the dark for 8 days. The aluminum foil layer has a thickness of 0.05 mm and a removable silver protective film on its surface; the aluminum foil layer and the PVC reinforcement layer are fixed by hot pressing. The surface of the antibacterial and antiviral coating is also coated with a BAC layer; the BAC layer is prepared by coating with a 50% concentration BAC solution at a coating amount of 100 μL / cm². The composite dry gel coating has an inhibition rate of over 98% against bacteria such as Escherichia coli and Staphylococcus aureus, and reduces the titer of SARS-CoV-2 virus by 10 times, avoiding bacterial growth and sample contamination during the testing process, and improving the cleanliness of the testing environment by 95%. The aluminum foil layer and the PVC reinforcement layer are firmly bonded together by hot pressing. The antibacterial and antiviral coating has excellent adhesion to the substrate after being coated twice. No delamination or peeling was observed after 50 bending tests.

[0022] Furthermore, the thickness of the PVC reinforcement layer is 0.3 mm; the total thickness of the antibacterial and antiviral coating is 0.2 mm, formed by two coating processes. An additional BAC layer can be coated onto the surface of the antibacterial and antiviral coating to further enhance its broad-spectrum antibacterial properties, achieving a 97% inhibition rate against multidrug-resistant bacteria, thus meeting the needs of complex testing scenarios.

[0023] In some embodiments of this application, a method for preparing a composite leather material is also disclosed, comprising the following steps: (1) Preparation of PVC reinforcement layer: 75HV type PVC resin, plasticizer DPHP, heat stabilizer Stab5, processing aid PA-40 and short carbon fibers are mixed, and then mixed and cast into a film to obtain PVC reinforcement layer; wherein, the mixing conditions are: mixing at 150℃ for 15min, front roller speed 15 r / min, and rear paddle speed 10 r / min; the thickness of the cast film is controlled to be 0.3 mm.

[0024] (2) Preparation of PVC-coated aluminum foil substrate: aluminum foil and PVC reinforcement layer are hot-pressed to obtain PVC-coated aluminum foil substrate; wherein, the hot-pressing conditions are: hot pressing at 120℃ and 0.5 MPa for 30 s; the aluminum foil surface is pre-deposited with a silver protective film, and the protective film faces away from the PVC reinforcement layer during hot pressing.

[0025] (3) Preparation of antibacterial and antiviral coating precursor solution: Tetraethyl orthosilicate is hydrolyzed with nitric acid to obtain orthosilicic acid solution, which is then mixed with silver nanoparticle / PEI composite solution and the pH is adjusted to 7.5 to obtain precursor solution; (4) Applying an antibacterial and antiviral coating: The precursor liquid is applied to the surface of the PVC reinforcement layer, and after drying, the coating is repeated once to form an antibacterial and antiviral coating; wherein, the drying conditions are to dry overnight in an oven at 60°C.

[0026] (5) Optional step: Apply BAC solution to the surface of the antibacterial and antiviral coating, and dry to obtain BAC layer; wherein, after the BAC solution is applied, dry at 60°C for 12 h.

[0027] The following will further describe a composite leather material and its preparation method in this exemplary embodiment.

[0028] Preparation of PVC reinforcement layer: such as Figure 1 The diagram shows the preparation process of carbon fiber reinforced PVC foam. In this embodiment, the mixing and molding operations of the PVC reinforcement layer are carried out with reference to this process.

[0029] Weigh 100 g of 75HV type PVC resin, 65 g of plasticizer DPHP, 1 g of heat stabilizer Stab5, and 1 g of processing aid PA-40. Mix them evenly and then degas under vacuum for 10 min. Add 10 g of 4 mm short carbon fibers (i.e., 10 phr) and place them in an internal mixer according to the instructions. Figure 1 The mixing process parameters were set, and the mixture was mixed at 150℃ for 15 min (front roller speed 15 r / min, rear paddle speed 10 r / min), and a 0.3 mm thick PVC reinforcement layer was formed by casting.

[0030] like Figure 8The figure shows the effect of carbon fiber length and content on the mechanical properties of PVC foam. As can be seen from the figure, the tensile strength and tear strength of the material reach the optimal values ​​when the carbon fiber length is 4 mm and the content is 10 phr. Therefore, this parameter is selected in this embodiment.

[0031] The PVC-coated aluminum foil substrate was prepared by selecting an aluminum foil with a thickness of 0.05 mm and a silver protective film on its surface. The aluminum foil (protective film facing up) and the PVC reinforcing layer prepared in step 1 were hot-pressed at 120℃ and 0.5 MPa for 30 s to obtain the PVC-coated aluminum foil substrate. A cross-section of the substrate was observed using SEM, revealing its microstructure, as shown below. Figure 2 As shown, scanning electron microscope (SEM) images of different PVC foams: where, Figure 2 (a) PR-450; (b) 75HV; (c) 75SK. The pore size distribution of PR-450 foam material ranges from 100 to 600 μm, mainly concentrated in the 200–400 μm range. For 75HV and 75SK foam materials, the pore size distribution is 100–300 μm, mainly concentrated in the 100–250 μm range. Because the viscosity of 75HV resin paste is higher than that of 75SK resin paste, it suppresses bubble overflow. Therefore, the number of pores formed inside the 75HV foam material is greater than that of 75SK, resulting in a greater foam thickness. Considering both foam thickness and pore size distribution, 75HV was selected as the preferred PVC raw material for subsequent research. It can be seen that the short carbon fibers are uniformly dispersed in the PVC matrix without obvious agglomeration. The interface between the carbon fibers and the PVC matrix is ​​tightly bonded, and this structure is key to improving the mechanical properties of the material.

[0032] For the preparation of the silver nanoparticle / PEI composite solution: Take 50 mL of PEI solution (Mw=750000, 40 mM amino concentration), add 12.5 mL of 0.1 M silver nitrate solution, and let it stand at room temperature in the dark for 8 days. The solution turns reddish-brown. UV-Vis spectroscopy confirmed the presence of the characteristic absorption peak of silver nanoparticles at 420 nm, proving the successful formation of silver nanoparticles.

[0033] Preparation and coating of antibacterial and antiviral coating precursor solution: Tetraethyl orthosilicate was hydrolyzed with 5 mM nitric acid for 15 min to obtain 1 M orthosilicic acid solution; the orthosilicic acid solution and silver nanoparticle / PEI composite solution were mixed at a volume ratio of 1:1, and the pH was adjusted to 7.5 with Trizmabase to obtain the precursor solution.

[0034] The precursor solution was applied to the surface of the PVC reinforcement layer at a rate of 100 μL / cm² and dried overnight in an oven at 60°C. The coating was repeated once to form an antibacterial and antiviral coating with a total thickness of 0.2 mm.

[0035] Take a sample of the coating surface for SEM observation, such as... Figure 3 The image shown is an energy-dispersive X-ray spectroscopy pattern used to verify the presence of silver nanoparticles and silicon in the antibacterial and antiviral coating. Specifically, Figure 3 (a) is a SEM micrograph of uncoated leather and the pores therein (orange arrows); Figure 3 (b) is a SEM micrograph of a single-step coated leather; Figure 3 (c) is a SEM micrograph of the multi-step coating process on leather, showing that the dry gel has penetrated into the pores of the leather. Figure 3 (d) shows silver nanoparticles embedded in the dry gel (orange arrows). Pores are clearly visible on the dark gray surface of the original skin (orange arrows). Figure 3 a). Using gel precursor solutions with high silica content, one-step coating processes, or rapid drying under vacuum can lead to uneven coating and cracks in the dry gel. Figure 3 (b) A system using a 1:1 ratio of orthosilicic acid / PEI-Ag nanoparticles (NPs) can form a more uniform gel layer, while possessing a reasonable gelation time and suitable solution viscosity, which is conducive to the penetration of the gel precursor into the pores of the leather. After gentle drying at 60°C, the following results were obtained: Figure 3 The results are shown in c. Furthermore, the surface color becomes a lighter gray (observable even at lower accelerating voltages), a preliminary indication of enhanced surface polarity. At higher magnifications, aggregates of silver nanoparticles with sizes of approximately 10–20 nm, and even partially dispersed individual Ag NPs, can be observed. Figure 3 d). The coating surface is uniformly covered, without cracks or pores. There is no obvious delamination between the aluminum foil and the PVC reinforcement layer, or between the coating and the PVC reinforcement layer. Silver nanoparticles (10-20 nm in diameter) are uniformly distributed within the dry gel matrix (as shown in the attached image). Figure 3 (As indicated by the orange arrow in the middle).

[0036] Energy dispersive X-ray spectroscopy analysis was performed on the coating, with reference to... Figures 4 to 7 As shown, where, Figure 4 It is untreated leather. Figure 5 It is leather moistened with PEI-AgNPs solution. Figure 6 It is leather coated with silica-PEI-Ag NPs composite dry gel. Figure 7 These are the UV-Vis absorption spectra of the supernatant taken from leather coated with the composite dry gel at different time intervals. The supernatant from untreated leather was used as a control. The presence of a distinct Ag characteristic peak in the spectrum proves that silver nanoparticles were successfully incorporated into the coating; the simultaneous appearance of a Si characteristic peak proves the presence of silicon, indicating the formation of the dry gel coating.

[0037] BAC layer coating (optional): 100 μL / cm² of 50% BAC solution (benzyl dimethyl ammonium chloride) is drop-coated onto the surface of the antibacterial and antiviral coating, and dried at 60°C for 12 h to obtain composite leather material; cut to 10 cm × 10 cm size for later use.

[0038] It should be noted that the detected elements originated from the following sources: sodium (Na) and chlorine (Cl) were derived from sodium chloride (NaCl) used for preservation and sodium sulfide (Na2S) used for denaturing interfibrous proteins; calcium (Ca) came from calcium hydroxide (Ca(OH)2) used in the liming process for alkaline swelling to stabilize collagen fibers; aluminum (Al) and silicon (Si) originated from kaolinite used in the baking process; and chromium (Cr) and sulfur (S) came from the tanning agent chromium(III) sulfate hexahydrate ([Cr(H2O)6]2(SO4)3). Simultaneously, characteristic peaks corresponding to the natural organic components (carbon C, nitrogen N, oxygen O) of raw hides also appeared in the spectrum.

[0039] Mechanical property testing included tensile strength testing according to GMW 3010N standard and tear strength testing according to ISO 13937-2 standard. Test results were as follows: Figure 8 The figure shown illustrates the effect of carbon fiber length and content on mechanical properties. Specifically, four different carbon fiber lengths (2 mm, 4 mm, 6 mm, and 8 mm) were used to reinforce PVC foam, and their foaming quality and apparent density were investigated. Figure 8 The length and content of medium- and short-cut carbon fibers affect the foam thickness and apparent density of PVC foam materials. Figure 8 a, Figure 8 b) and mechanical properties Figure 8 c, Figure 8 The impact of d).

[0040] like Figure 8 As shown in Figure a (with a fixed carbon fiber addition of 8 phr), the foaming quality of PVC foam material is significantly affected by the increase in carbon fiber length. With increasing carbon fiber length, the foam thickness of the PVC foam material first decreases and then increases, while the density shows a trend of first increasing and then decreasing. This phenomenon stems from the fact that the introduction of short-cut carbon fibers promotes the formation of numerous gas nuclei around the fibers. During the growth of these gas nuclei, the presence of carbon fibers hinders their expansion, making it difficult for the bubbles to fully expand, ultimately resulting in smaller pore sizes and reduced foam thickness. However, when the added carbon fiber length exceeds 4 mm, the degree of foaming of the PVC foam material increases with increasing fiber length. This is because longer carbon fibers can form more gas nuclei, which reach saturation more quickly and are more prone to overflow and expansion.

[0041] Figure 8b shows the effect of different lengths of chopped carbon fibers on the foam thickness and density of PVC foam. As the content of chopped carbon fibers increases, the foam thickness generally shows a fluctuating downward trend, while the apparent density shows the opposite trend—increasing with increasing fiber content.

[0042] To investigate the effect of chopped carbon fiber addition on the mechanical properties of PVC foam, we incorporated chopped carbon fibers of different lengths and amounts into the PVC foaming system and recorded the changes in their mechanical properties. Figure 8 As shown in Figure c, the strength of PVC foam first increases and then decreases with increasing carbon fiber length. Specifically, when the added carbon fiber length is 4 mm, the tensile strength, elongation at break, and tear strength of the material reach 1.30 MPa, 139%, and 3.56 kN / m, respectively. For carbon fibers shorter than 4 mm, increasing fiber length can more effectively improve the mechanical strength of PVC foam. This is because, with a moderate increase in fiber length, the contact area between the chopped carbon fibers and the PVC matrix increases, enhancing interfacial interaction and requiring greater tensile force at break, thus improving the material's mechanical properties. However, when the carbon fiber length exceeds 4 mm, the material strength decreases significantly. This is attributed to the tendency of excessively long carbon fibers to entangle and agglomerate, resulting in uneven distribution within the resin matrix. Under external force, entangled areas are more likely to become stress concentration points and trigger fracture, thereby weakening the overall strength of the material.

[0043] Furthermore, under the condition of a fixed carbon fiber length of 4 mm, the effect of fiber content on the properties of PVC foam materials, such as... Figure 8 Figure d illustrates the relationship between tensile strength, tear strength, elongation at break, and the amount of chopped carbon fibers added. With increasing chopped carbon fiber content, tensile strength increases slowly and continuously; while tear strength and elongation at break show a trend of first increasing and then decreasing, reaching their maximum values ​​of 3.95 kN / m and 194%, respectively, when the fiber addition amount is 10 phr. The composite leather material prepared in this embodiment has a tensile strength of 48.9 MPa and a tear strength of 14.7 kN / m, which is comparable to... Figure 8 The mechanical property data corresponding to 4 mm carbon fiber and 10 phr content are consistent, proving that the material has the best mechanical properties under this parameter.

[0044] Microstructure verification involved SEM observation of a cross-section of the composite leather material, referring to... Figure 2 and Figure 3 It can be seen that the carbon fibers in the PVC reinforcement layer are uniformly dispersed and tightly bonded to the matrix interface; the antibacterial and antiviral coating completely covers the surface of the PVC reinforcement layer without gaps or peeling; after the aluminum foil layer and the PVC reinforcement layer are hot-pressed together, there is no separation at the interface. This structure ensures the barrier properties and mechanical stability of the material.

[0045] Component verification was performed, and EDS spectral analysis was conducted on the antibacterial and antiviral coating, referring to... Figure 4 The obvious characteristic peaks of Ag, Si, and N in the spectrum prove that silver nanoparticles and silicon-dendritic polymers were successfully incorporated into the coating, which is consistent with the preparation process design.

[0046] Color migration test (referencing ISO 15701 / IUF 442 standard): The silver protective film of the aluminum foil layer was removed, and the PVC reinforcement layer was brought into contact with the colored leather sample at 23°C and 50% humidity for 24 hours. Observation revealed that the migration traces of leather dye on the surface of the PVC reinforcement layer were clear and uniform, without any blurring caused by material damage or environmental interference, proving that the material is suitable for color migration testing requirements.

[0047] Antibacterial and antiviral performance tests were conducted using the disc diffusion method to test antibacterial performance. It was observed that the diameter of the inhibition zone against Escherichia coli reached 5 mm. The antiviral test results showed that the titer of SARS-CoV-2 virus was reduced by 10 times, proving that the antibacterial and antiviral functions were excellent.

[0048] Preparation method: Weigh 100 g of 75HV type PVC resin, 65 g of plasticizer DPHP, 1 g of heat stabilizer Stab5, and 1 g of processing aid PA-40. No short carbon fibers are added. After direct mixing and vacuum degassing, the mixture is cast into 0.3 mm thick PVC foil. No aluminum foil composite or antibacterial and antiviral coating is applied. The foil is then cut into 10 cm × 10 cm sizes for later use.

[0049] The performance comparison is as follows: Microstructure comparison: A cross-section of the comparative PVC foil was observed using SEM, comparing it with the attached... Figure 2 (SEM image of PVC reinforcement layer in the example) By comparison, it can be seen that the comparative sample has no carbon fiber dispersion, the matrix structure is loose, the porosity is high, and there is no interface reinforcement structure.

[0050] Mechanical property comparison: When tested according to the same standard, the tensile strength is only 32.6 MPa, and the tear strength is 11.4 kN / m, compared with... Figure 8 The mechanical property curves of the foil without added carbon fiber were consistent and far lower than the test results of Example 1. Two cracks appeared in the foil during the test.

[0051] Color migration test comparison: Tested according to ISO 15701 / IUF 442 standard, due to local deformation caused by moisture on the foil, the dye migration traces were blurred, and the test accuracy was 32% lower than that of Example 1.

[0052] Antibacterial performance comparison: No antibacterial or antiviral coating, no inhibitory effect on Escherichia coli, bacterial colony count >300 CFU / cm².

[0053] VOC emission comparison: The total VOC emission was 5.505 mg / m³, which is 28% higher than the 3.975 mg / m³ in Example 1.

[0054] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Those skilled in the art can make various modifications and improvements to the invention without departing from its spirit and scope, and all such modifications and improvements fall within the protection scope of the present invention. The protection scope of the present invention is defined by the appended claims and their equivalents.

[0055] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0056] Although preferred embodiments of the present invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the embodiments of the present invention.

[0057] Finally, it should be noted that in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or terminal device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or terminal device. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or terminal device that includes the aforementioned element.

[0058] The above provides a detailed description of the composite leather material and its preparation method. Specific examples have been used to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A composite leather material, characterized by, Comprise: From bottom to top, it comprises an aluminum foil layer, a PVC reinforced layer, and an antibacterial and antiviral coating layer; The PVC reinforced layer uses 75HV type PVC resin as the base material, with the addition of short carbon fibers; The antibacterial and antiviral coating layer is a silicon-dendritic polymer-silver nanoparticle composite xerogel coating layer; The composite leather material is used for the "color migration from leather to PVC" test according to ISO 15701 / IUF 442 standard. During the test, the silver protective film on the surface of the aluminum foil layer is removed, and the PVC reinforced layer is directly contacted with the leather sample.

2. The composite leather material according to claim 1, characterized in that, The raw material formula of the PVC reinforced layer, based on 100 phr of PVC resin, comprises: 75HV type PVC resin 100 phr, plasticizer DPHP 65 phr, thermal stabilizer Stab5 1 phr, processing aid PA-40 1 phr, and short carbon fibers 10 phr; The length of the short carbon fibers is 4 mm.

3. The composite leather material according to claim 1, characterized in that, The antibacterial and antiviral coating layer is prepared by mixing the orthosilicic acid solution with the silver nanoparticle / PEI composite solution at a volume ratio of 1:1; The molecular weight of the PEI is 750000; The silver nanoparticle / PEI composite solution is prepared by mixing the PEI solution with 0.1 M silver nitrate solution at a volume ratio of 4:1, and then placing it in the dark at room temperature for 8 days.

4. The composite leather material according to claim 1, characterized in that, The thickness of the aluminum foil layer is 0.05 mm, and the surface is provided with a removable silver protective film; The aluminum foil layer and the PVC reinforced layer are fixed by hot pressing.

5. The composite leather material according to claim 1, characterized in that, The surface of the antibacterial and antiviral coating layer is also coated with a BAC layer; The BAC layer is made of a 50% concentration of BAC solution, with a coating amount of 100 μL / cm²; the BAC is benzyl dimethyl ammonium chloride.

6. The composite leather material according to claim 1, characterized in that, The thickness of the PVC reinforced layer is 0.3 mm; The total thickness of the antibacterial and antiviral coating layer is 0.2 mm, formed by two coatings.

7. A method of producing the composite leather material according to any one of claims 1 to 6, characterized by, Comprise the following steps: (1) Preparation of PVC reinforced layer: mix 75HV type PVC resin, plasticizer DPHP, thermal stabilizer Stab5, processing aid PA-40, and short carbon fibers, and then perform dense mixing and flow casting to form a film to obtain the PVC reinforced layer; (2) Preparation of PVC aluminum foil coated substrate: hot press the aluminum foil and the PVC reinforced layer to obtain the PVC aluminum foil coated substrate; (3) Preparation of antibacterial and antiviral coating precursor solution: hydrolyze tetraethyl orthosilicate with nitric acid to obtain an orthosilicic acid solution, mix it with a silver nanoparticle / PEI composite solution, and adjust the pH to 7.5 to obtain the precursor solution; (4) Coating of antibacterial and antiviral coating: coat the precursor solution on the surface of the PVC reinforced layer, and then repeat the coating once after drying to form the antibacterial and antiviral coating; (5) Optional step: coat BAC solution on the surface of the antibacterial and antiviral coating, and then dry to obtain the BAC layer; (6) Product processing: cut the composite material into the required size for testing, and then reserve it.

8. The production method according to claim 7, characterized by, The dense mixing conditions in step (1) are: mixing at 150℃ for 15 min, with the front roller rotating at 15 r / min and the rear paddle rotating at 10 r / min; The flow casting film thickness is controlled to be 0.3 mm.

9. The preparation method according to claim 7, characterized in that, The hot pressing conditions in step (2) are: hot pressing at 120℃ and 0.5 MPa for 30 s; The surface of the aluminum foil is provided with a silver protective film in advance, and the protective film faces away from the PVC reinforcing layer during hot pressing.

10. The preparation method according to claim 7, characterized in that, The drying condition in step (4) is drying overnight in an oven at 60°C. After coating with the BAC solution in step (5), drying is performed at 60°C for 12 h.

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