Green antibacterial and detoxification modified nitrocellulose leather finishing agent, preparation method and application

Abstract

The application discloses a kind of green antibacterial detoxification modified nitration cotton leather finishing agent, preparation method and application, the leather finishing agent with general water-based nitration cotton emulsion as film-forming matrix, with about 0.1% solid content of super low addition amount, through the etherification grafting reaction of surface hydroxyl activation middle krypton zinc core antibacterial dispersion liquid and nitration cotton molecular chain, form the modified film-forming system of chemical bond, and be formed by compounding with leather finishing general environmental protection auxiliary agent.The application fundamentally solves the industry pain point of existing antibacterial finishing agent, only one thousandth of pure zinc core solid content, it can realize the antibacterial rate of > 99.99% to staphylococcus aureus, escherichia coli and other pathogenic bacteria, the antiviral activity rate of > 99.9% to influenza a virus H3N2;Film-forming hand feeling is excellent, completely retains the natural texture of dermis, single-component room temperature film-forming, perfect adaptation existing mass production process of leather industry, environmental protection compliance, can be widely applied to the top coating treatment of automotive interior, household sofa, high-end luggage and other leather products.

Description

Technical Field

[0001] This invention belongs to the field of leather chemical materials technology, specifically relating to an antibacterial and detoxifying functional leather topcoat for topcoat treatment, and particularly to an ultra-low addition amount of medium-krypton zinc core modified nitrocellulose antibacterial and detoxifying leather finishing agent and its preparation method. Background Technology

[0002] Leather finishing is the final core process in leather tanning. The topcoat directly forms the outermost film of leather products, determining the leather's feel, appearance, weather resistance, mechanical properties, and additional functions. With rising consumer demand and increased public health awareness, the need for antibacterial and detoxifying functions in leather products, such as automotive interiors, home sofas, high-end bags, and footwear, is becoming increasingly urgent. Functional leather finishing agents have become a hot research topic in the industry.

[0003] Existing antibacterial and detoxifying leather finishing agents are mainly divided into two major systems: polyurethane (PU)-based and nitrocellulose-based. Both systems suffer from the following unresolved industry pain points regarding antibacterial properties: 1. Inherent defects of polyurethane-based coatings: The film is highly dense with poor air permeability, which can easily cause sweating and odors with long-term use; Antibacterial powder can only be added through physical encapsulation, which is prone to agglomeration, migration, and precipitation, and the antibacterial effect decays rapidly with use, resulting in extremely poor batch stability; Two-component polyurethane requires strict control of curing temperature and ratio, has a narrow process window, and is difficult for existing production lines of downstream small and medium-sized leather factories to adapt to, resulting in high transformation costs and environmental safety risks from carcinogenic substances such as free isocyanates.

[0004] 2. Existing antibacterial modification solutions based on nitrocellulose have significant technical bottlenecks: Nitrocellulose, as a commonly used topcoat substrate in the leather industry, has core advantages such as soft and smooth film formation, not covering the natural texture of genuine leather, strong adhesion, and wide process adaptability. However, existing antibacterial modification solutions are all simple physical blending. The nano antibacterial powder and the nitrocellulose matrix are only physically combined, which easily leads to problems such as powder agglomeration and poor compatibility with resin. Even with high addition levels, it is difficult to achieve long-term and stable antibacterial and detoxifying effects, and it is difficult to stably achieve a high antibacterial rate of 99.99% and antiviral activity of over 99.9%.

[0005] 3. Antibacterial effect and film-forming performance cannot be simultaneously achieved, and high addition amounts bring multiple defects: To achieve an antibacterial rate of over 99%, existing antibacterial coatings generally require an addition amount of 2%-5% of antibacterial active ingredients. This not only significantly increases raw material costs but also leads to problems such as decreased film-forming properties, poor hand feel, easy powder precipitation, coating gloss loss, and decreased bending resistance. It is impossible to balance antibacterial effect with the core performance of leather finishing. On the other hand, with low addition amounts, existing technologies cannot achieve a stable high antibacterial rate, let alone antiviral effects.

[0006] 4. The existing antibacterial system suffers from a cost-performance imbalance, with significant bottlenecks in large-scale promotion: Silver ion antibacterial agents, which have a large market share in the current technology, are expensive, prone to photochromism, severely affecting the appearance of leather, and pose a risk of heavy metal leaching; ordinary zinc ion antibacterial agents have low antibacterial activity and poor compatibility with organic film-forming matrices, requiring high addition levels to barely meet standards, thus failing to meet the functional requirements of high-end scenarios; at the same time, most existing functional coating agents require downstream factories to modify production lines and adjust core processes, resulting in extremely high barriers to large-scale promotion and making them unsuitable for the existing general production processes in the leather industry.

[0007] Therefore, developing a nitrocellulose-based antibacterial and detoxifying coating agent that can achieve top-notch long-lasting antibacterial and detoxifying effects with ultra-low addition amounts, does not damage the natural texture of leather, is compatible with existing mass production processes, and is environmentally friendly and compliant is a technical challenge that the leather industry urgently needs to solve. Summary of the Invention

[0008] To address the aforementioned deficiencies in existing technologies, the present invention aims to provide a green antibacterial and detoxifying modified nitrocellulose leather finishing agent, its preparation method, and its application. This leather finishing agent requires only an ultra-low addition amount of 0.01% to 0.5% solid content to achieve chemical bonding between antibacterial powder and the nitrocellulose matrix, resulting in top-tier and long-lasting antibacterial and detoxifying effects, without damaging the leather texture, and with zero barriers to entry for existing mass production processes. It is an environmentally friendly and compliant zinc-modified nitrocellulose antibacterial and detoxifying leather finishing agent. The invention also provides a method for its industrially mass production.

[0009] To achieve the above-mentioned objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a green antibacterial and detoxifying modified nitrocellulose leather finishing agent, comprising the following components in a total of 100 parts by weight: 25-40 parts of water-based nitrocellulose emulsion; 0.8-1.2 parts of a 10% solids content aqueous dispersion of a krypton-zinc nuclear antibacterial modifier; 3-8 parts of film-forming aid; 0.5-2 parts of wetting and dispersing agent; 2-6 parts of film-forming regulator; The remainder is deionized water; The core parameters are precisely defined as follows: The 10% solids content of the krypton-zinc core antibacterial modifier aqueous dispersion is a stable aqueous dispersion of the surface hydroxylated activated nano-zinc-based composite antibacterial powder independently developed by the applicant. The powder particle size is 20-50 nm, the elemental zinc content is ≥45%, and the powder surface has a large number of active hydroxyl groups. In the finished coating agent, the solids content of the krypton-zinc core antibacterial modifier is 0.01-0.5%; the solids content of the pure krypton-zinc core is 0.08%-0.12%, and the optimal addition amount is 1 part of 10% aqueous dispersion, corresponding to the solids content of the pure zinc core. This invention uses a zinc core antibacterial modifier as its core component, and integrates this antibacterial adjuvant, the zinc core, with a specific product—leather finishing agent—at the application level. It fully utilizes the physicochemical properties of the leather finishing agent itself to achieve etherification grafting bonding between the zinc core and nitrocellulose, fundamentally changing the physicochemical properties of existing leather finishing agents. It effectively breaks through the bottleneck that existing antibacterial materials cannot achieve, and innovatively combines antibacterial properties into leather finishing agents to form a groundbreaking new leather material.

[0010] In some embodiments, the aqueous nitrocellulose emulsion is a low-nitrogen aqueous nitrocellulose emulsion specifically for leather finishing, with a nitrogen content of 11.5%-12.2% and a solid content of 28%-32%. It is a common bulk raw material in the leather industry, perfectly adapted to existing leather tanning processes, and fully compatible with the core matrix of the Safety Data Sheet (SDS).

[0011] In some embodiments, the film-forming aid is isooctyl acetate, the wetting and dispersing agent is tridecyl alcohol ethoxylate, and the film-forming regulator is isopropanol. All of the above components are common environmentally friendly auxiliaries used in the leather finishing industry, and are completely consistent with the components reported by SDS, with no additional environmental risks.

[0012] In some implementations, 0.1-1 parts of functional additives may also be added, including one or more of defoamers, leveling agents, and pH adjusters. These are all general additives for water-based coatings and do not affect the core performance and compliance of the system.

[0013] Secondly, the present invention provides a method for preparing the above-mentioned leather finishing agent, comprising the following steps: S1, Prepare the aqueous dispersion of the zinc-core antibacterial modifier: Weigh out 10% of the zinc-core antibacterial modifier powder for feeding; take the remaining amount of deionized water and place it in a clean stirring container. Add the zinc-core antibacterial modifier powder to the deionized water in 3 to 5 portions. After each addition, stir at a low speed of no more than 1000 r / min for 3 to 5 minutes until the addition is completed. Continue stirring for 10 to 30 minutes. S2, Activation pretreatment of Zhongke zinc core antibacterial modifier: Mix 10% solid content Zhongke zinc core antibacterial modifier aqueous dispersion with 10%-20% deionized water (by weight of leather finishing agent), add wetting and dispersing agent, stir at low speed at 1500-2000 rpm for 10-20 min, and then sonicate at 300-500W for 15-30 min to obtain a uniform pre-dispersion without agglomeration; adjust the pH of the pre-dispersion to 8.5-9.5 with pH adjuster (food grade ammonia), heat to 50-60℃ and stir for 30-60 min to complete the activation of hydroxyl groups on the powder surface, and obtain activated zinc core dispersion.

[0014] S3, pre-grafted modification of zinc-core nitrocellulose: Add the aqueous nitrocellulose emulsion to the reactor and heat it to 55-65℃. While stirring at a low speed of 800-1200 rpm, slowly add the activated zinc core dispersion prepared by S2 to the nitrocellulose emulsion. The addition time is controlled to be 30-60 min. After the addition is completed, keep the mixture warm and stir for 2-4 h to allow the active hydroxyl groups on the surface of the activated zinc core powder to undergo an etherification grafting reaction with the hydroxyl groups on the nitrocellulose molecular chain. This allows the activated zinc core powder to become part of the nitrocellulose molecular chain through chemical bonding, rather than simple physical mixing, thus obtaining the zinc core modified nitrocellulose base material.

[0015] S4, coating compound molding: Add film-forming aids and film-forming regulators to the zinc core modified nitrocellulose base material prepared by S3, and stir at 1500-2500 rpm for 20-40 min; add the remaining deionized water to adjust the solid content of the system to 25%-35%, add optional functional additives, stir evenly, and then filter through a 200-mesh filter to obtain the green antibacterial and detoxifying modified nitrocellulose leather agent.

[0016] Thirdly, the present invention provides the application of the above-mentioned green antibacterial and detoxifying modified nitrocellulose leather agent in the production of leather products. The application includes using the finishing agent as a top coat treatment for leather products.

[0017] In some embodiments, the topcoat treatment is applied by roller coating, spraying, curtain coating or hand coating, with 1-2 coats applied. After application, it dries at room temperature to form a film without the need for UV curing and allows for post-treatment.

[0018] Compared with the prior art, the present invention has the following outstanding advantages: 1. Achieving top-notch antibacterial and detoxifying effects and ultimate cost-effectiveness with ultra-low additive dosage, breaking through industry technical bottlenecks.

[0019] This invention utilizes hydroxyl activation and etherification grafting technology to chemically bond the zinc-core antibacterial powder to the nitrocellulose molecular chain, achieving 100% full exposure of the antibacterial active sites. This completely solves the core defects of physical blending systems, such as powder agglomeration, encapsulation of active sites, and low effective utilization. With an ultra-low addition of only 0.1% solid content (one-thousandth), it achieves performance far exceeding that of conventional products with high addition amounts in the industry: Authoritative testing by the Guangdong Provincial Center for Microbiology Analysis and Testing, which is dual-accredited by CNAS and CMA, shows that the leather coated with this invention exhibits antibacterial rates >99.99% against Staphylococcus aureus, Escherichia coli, and Staphylococcus aureus, a 99% antibacterial rate against Candida albicans, and a 24-hour antiviral activity rate >99.9% against influenza A virus H3N2. After 1000 bends and 500 alcohol wipes, the antibacterial rate remains above 99%, demonstrating a long-lasting effect far exceeding existing technologies.

[0020] 2. It does not damage the core properties of the leather at all, perfectly preserving its natural texture.

[0021] This invention employs an ultra-low addition amount of 0.1%, completely preserving the core film-forming properties of the original nitrocellulose system. This fundamentally avoids problems such as decreased film-forming properties, poor hand feel, and coating gloss loss caused by high addition amounts. The prepared coating forms a soft and smooth film that does not obscure the natural texture of genuine leather, has no plastic feel, and does not become sticky or attract dust in high-temperature and high-humidity environments. The modified coating further enhances adhesion, bending resistance, scratch resistance, and yellowing resistance. Both single-coat and two-coat processes can consistently meet standards, making it perfectly suitable for all types of leather applications, including shoe uppers, bag leather, automotive interior leather, and home sofa leather.

[0022] 3. Extremely cost-effective and highly adaptable to the entire industry chain.

[0023] This invention achieves top-tier functionality with an ultra-low addition of only 0.1%, resulting in minimal increase in raw material costs while enabling end-product leather to achieve a significantly higher functional premium. Simultaneously, the coating agent is a single-component water-based system that evaporates and forms a film at room temperature, requiring no additional curing process. It is perfectly compatible with all existing leather industry processes, including roller coating, spray coating, curtain coating, and hand coating. Downstream factories can directly replace their existing topcoat agents to produce antibacterial and detoxifying functional leather without modifying production lines, adjusting core processes, or retraining workers. This zero-barrier product upgrade has the potential to drive large-scale application across the entire industry.

[0024] 4. Environmentally compliant and highly safe.

[0025] The system of this invention is an aqueous formulation with low VOC content, free of free isocyanates, heavy metals, and phthalic plasticizers, and complies with EU REACH, RoHS and domestic GB / T series standards. The core components are fully compatible with the SEALACQUER WE 760 Safety Data Sheet (SDS). The product has undergone safety assessment and is classified as only oral acute toxicity category 5 and severe eye irritation category 1, with no other health hazards. It meets the safety requirements for automotive interiors, home furnishings, and food contact scenarios, and has no environmental compliance risks. Detailed Implementation

[0026] The described embodiments are merely some, not all, of the embodiments of the present invention. Furthermore, any modifications, equivalent substitutions, or improvements made by those skilled in the art based on the embodiments of the present invention without inventive effort should be included within the scope of protection of the present invention.

[0027] In all the following embodiments, the "10% Zhongke Zinc Core Aqueous Dispersion" refers to an aqueous dispersion of surface-hydroxylated nano-zinc-based composite antibacterial powder (Zhongke Zinc Core) with a solid content of 10%. The formula for converting the solid content of pure Zhongke Zinc Core corresponding to its addition amount is: pure zinc core solid content = 10% aqueous dispersion addition amount × 10%. First, it should be noted that the "Zhongke Zinc Core" mentioned in this invention is a super-energy zinc core structure independently developed by the applicant and inventors based on "electron beam confinement technology". It is mainly composed of nano-zinc oxide or zinc-based composites. Zhongke Zinc Core Powder refers to surface-hydroxylated activated nano-zinc-based composite antibacterial powder with a particle size of approximately 100-500 nm, a zinc content of ≥75%, and a large number of active hydroxyl groups on the surface. It is currently available on the market.

[0028] Example 1: A green antibacterial and detoxifying modified nitrocellulose leather agent and its preparation method (0.1% addition of zinc core). This embodiment provides a krypton-zinc core-modified nitrocellulose antibacterial and detoxifying leather finishing agent, with a total weight of 100 parts, and the following formula: Aqueous nitrocellulose emulsion (nitrogen content 11.8%, solid content 30%): 35 parts 10% solids content krypton-zinc nuclear antibacterial modifier aqueous dispersion: 1 part (corresponding to 0.1% pure zinc nuclear solids content in the total mass) Isooctyl acetate: 5 parts Ethylene oxide tridecyl alcohol: 1 part Isopropanol: 4 parts Deionized water: 53.7 parts Organosilicon defoamer: 0.2 parts Polyurethane leveling agent: 0.1 parts The preparation method is as follows: S1. Prepare an aqueous dispersion of the zinc-core antibacterial modifier. Take a certain amount of the zinc-core antibacterial modifier powder. Take deionized water at a ratio of powder to deionized water of 10% and place it in a clean stirring container. Add the zinc-core antibacterial modifier powder to the deionized water in three portions. After each addition, stir at a low speed of 1000 r / min for 5 minutes. After the three additions are completed, continue stirring for 10 to 30 minutes to obtain an aqueous dispersion of the zinc-core antibacterial modifier with a solid content of 10%. S2, Activation pretreatment of the zinc core antibacterial modifier: Mix 1 part of 10% solid content zinc core aqueous dispersion with 10 parts of deionized water, add 1 part of tridecyl ethoxylate, stir at 1800 rpm for 15 min, and then sonicate at 400W for 20 min to obtain a uniform predispersant; adjust the pH of the predispersant to 9.0 with food-grade ammonia solution, heat to 55℃ and stir for 45 min to complete the surface hydroxyl activation and obtain the activated zinc core dispersion.

[0029] S3, Pre-grafting modification of zinc core-nitrocellulose: 35 parts of aqueous nitrocellulose emulsion were added to a reactor and heated to 60°C. Under low-speed stirring at 1000 rpm, the activated zinc core dispersion was slowly added dropwise to the nitrocellulose emulsion for 45 min. After the addition was completed, the mixture was kept at 60°C and stirred for 3 h to complete the etherification grafting reaction and obtain zinc core modified nitrocellulose base material.

[0030] S4, Coating agent compounding and molding: Add 5 parts isooctyl acetate and 4 parts isopropanol to zinc core modified nitrocellulose base material, stir at 2000 rpm for 30 min; add the remaining 43.7 parts deionized water, add defoamer and leveling agent, stir evenly, and then filter through a 200 mesh filter to obtain the finished leather coating agent.

[0031] Authoritative performance verification: The coating agent of this embodiment was used to apply a two-coat top coat to cowhide, with a wet coating amount of 8 g / ㎡. After drying at room temperature, the film was sent to the Guangdong Provincial Center for Microbiology Analysis and Testing for testing. The test results are as follows (corresponding report numbers: 2026FM02311R01 to R05): 1. Antibacterial properties: Antibacterial rate against Staphylococcus aureus AS1.89 > 99.99%, antibacterial rate against Escherichia coli AS1.90 > 99.99%, antibacterial rate against Staphylococcus aureus GDMCC1.247 > 99.99%, and antibacterial rate against Candida albicans ATCC10231 99%; 2. Antiviral properties: Antiviral activity against influenza A virus H3N2 (ATCC VR-1679) for 24 hours >99.9%; 3. Long-lasting performance: After 1000 bends and 500 wipes with 75% alcohol, the antibacterial rate against the above-mentioned pathogens is still ≥99.2%; 4. Leather performance: The film forms a dry and smooth film, completely preserving the natural texture of genuine leather. It has an adhesion grade of 0, can withstand ≥10,000 flexes without cracking, and its scratch resistance and yellowing resistance meet the superior product standards of the leather top coating industry.

[0032] Example 2: A green antibacterial and detoxifying modified nitrocellulose leather agent and its preparation method (lower limit of zinc nucleus addition). This embodiment provides a krypton-zinc core-modified nitrocellulose antibacterial and detoxifying leather finishing agent, with a total weight of 100 parts, and the following formula: Aqueous nitrocellulose emulsion (nitrogen content 11.8%, solid content 30%): 35 parts 0.8 parts of a 10% solids content krypton-zinc nuclear antibacterial modifier aqueous dispersion (corresponding to a pure zinc nuclear solids content of 0.08%) Isooctyl acetate: 5 parts Ethylene oxide tridecyl alcohol: 1 part Isopropanol: 4 parts Deionized water: 53.9 parts Organosilicon defoamer: 0.2 parts Polyurethane leveling agent: 0.1 parts The preparation method is completely consistent with that in Example 1.

[0033] Performance verification: Tests showed that the leather coated in this embodiment had an antibacterial rate of >99.9% against Staphylococcus aureus and Escherichia coli, and an antiviral activity rate of >99% against influenza A virus H3N2. The film-forming performance was consistent with that of Example 1, which can meet the needs of mass production scenarios.

[0034] Example 3: A green antibacterial and detoxifying modified nitrocellulose leather agent and its preparation method (upper limit of zinc nucleus addition). This embodiment provides a krypton-zinc core-modified nitrocellulose antibacterial and detoxifying leather finishing agent, with a total weight of 100 parts, and the following formula: Aqueous nitrocellulose emulsion (nitrogen content 11.8%, solid content 30%): 35 parts 1.2 parts of a 10% solids content krypton-zinc nuclear antibacterial modifier aqueous dispersion (corresponding to a pure zinc nuclear solids content of 0.12%) Isooctyl acetate: 5 parts Ethylene oxide tridecyl alcohol: 1 part Isopropanol: 4 parts Deionized water: 53.5 parts Organosilicon defoamer: 0.2 parts Polyurethane leveling agent: 0.1 parts The preparation method is completely consistent with that in Example 1.

[0035] Performance verification: The antibacterial and antiviral properties of the leather coated in this embodiment are basically the same as those in Example 2, with no significant improvement. The film-forming performance still meets the industry's superior product standard and can meet the needs of high-requirement scenarios such as medical and public transportation.

[0036] Example 4: A green antibacterial and detoxifying modified nitrocellulose leather agent and its preparation method (upper and lower limits for other formulations). This embodiment provides a krypton-zinc core-modified nitrocellulose antibacterial and detoxifying leather finishing agent, with a total weight of 100 parts, and the following formula: Water-based nitrocellulose emulsion (nitrogen content 11.8%, solid content 30%): 25 parts 10% solids content krypton-zinc nuclear antibacterial modifier aqueous dispersion: 1 part (corresponding to 0.1% pure zinc nuclear solids content) Isooctyl acetate: 8 parts Ethylene oxide of tridecyl alcohol: 0.5 parts Isopropanol: 6 parts Deionized water: 59.3 parts Organosilicon defoamer: 0.1 parts Polyurethane leveling agent: 0.1 parts The preparation method is completely consistent with that in Example 1.

[0037] Performance verification: The antibacterial and antiviral properties of the leather coated in this embodiment are basically the same as those in Example 1, with no significant improvement. The film-forming performance still meets the industry's superior product standard and can meet the needs of high-requirement scenarios such as medical and public transportation.

[0038] Example 5: A green antibacterial and detoxifying modified nitrocellulose leather agent and its preparation method (upper and lower limits for other formulations). This embodiment provides a krypton-zinc core-modified nitrocellulose antibacterial and detoxifying leather finishing agent, with a total weight of 100 parts, and the following formula: Aqueous nitrocellulose emulsion (nitrogen content 11.8%, solid content 30%): 40 parts 10% solids content krypton-zinc nuclear antibacterial modifier aqueous dispersion: 1 part (corresponding to 0.1% pure zinc nuclear solids content) Isooctyl acetate: 3 parts Ethylene oxide tridecyl alcohol: 2 parts Isopropanol: 2 parts Deionized water: 50 parts Silicone defoamer: 1 part Polyurethane leveling agent: 1 part The preparation method is completely consistent with that in Example 1.

[0039] Performance verification: The antibacterial and antiviral properties of the leather coated in this embodiment are basically the same as those in Example 1, with no significant improvement. The film-forming performance still meets the industry's superior product standard and can meet the needs of high-requirement scenarios such as medical and public transportation.

[0040] Example 6: A green antibacterial and detoxifying modified nitrocellulose leather agent and its preparation method (upper and lower limits of nitrogen content in aqueous nitrocellulose emulsion) This embodiment provides a krypton-zinc core-modified nitrocellulose antibacterial and detoxifying leather finishing agent, with a total weight of 100 parts, and the following formula: Water-based nitrocellulose emulsion (nitrogen content 11.5%, solid content 32%): 40 parts 10% solids content krypton-zinc nuclear antibacterial modifier aqueous dispersion: 1 part (corresponding to 0.1% pure zinc nuclear solids content) Isooctyl acetate: 5 parts Ethylene oxide tridecyl alcohol: 1 part Isopropanol: 4 parts Deionized water: 53.7 parts Organosilicon defoamer: 0.2 parts Polyurethane leveling agent: 0.1 parts The preparation method is completely consistent with that in Example 1.

[0041] Performance verification: The antibacterial and antiviral properties of the leather coated in this embodiment are basically the same as those in Example 1, with no significant improvement. The film-forming performance still meets the industry's superior product standard and can meet the needs of high-requirement scenarios such as medical and public transportation.

[0042] Example 7: A green antibacterial and detoxifying modified nitrocellulose leather agent and its preparation method (upper and lower limits of nitrogen fixation content in water-based nitrocellulose emulsion) This embodiment provides a krypton-zinc core-modified nitrocellulose antibacterial and detoxifying leather finishing agent, with a total weight of 100 parts, and the following formula: Aqueous nitrocellulose emulsion (nitrogen content 12.2%, solid content 28%): 35 parts 10% solids content krypton-zinc nuclear antibacterial modifier aqueous dispersion: 1 part (corresponding to 0.1% pure zinc nuclear solids content) Isooctyl acetate: 5 parts Ethylene oxide tridecyl alcohol: 1 part Isopropanol: 4 parts Deionized water: 53.7 parts Organosilicon defoamer: 0.2 parts Polyurethane leveling agent: 0.1 parts The preparation method is completely consistent with that in Example 1.

[0043] Performance verification: The antibacterial and antiviral properties of the leather coated in this embodiment are basically the same as those in Example 1, with no significant improvement. The film-forming performance still meets the industry's superior product standard and can meet the needs of high-requirement scenarios such as medical and public transportation.

[0044] Comparative Example 1 (blank control group, without added kryptonite and zinc nuclei) This comparative example provides a common nitrocellulose leather finishing agent with the same formulation as Example 1, except that it does not contain the aqueous dispersion of the zinc-containing antibacterial modifier. The preparation method is the same as that of Example 1.

[0045] Performance verification: Tests showed that the antibacterial rate of the leather coated in this comparative example against Staphylococcus aureus and Escherichia coli was <10%, indicating no antibacterial or detoxifying effect.

[0046] Comparative Example 2 (physical blending control group, non-grafted modification, same addition amount) This comparative example provides a physically blended zinc ion antibacterial nitrocellulose coating agent with a formulation that is completely consistent with that of Example 1. The preparation method omits the S1 activation pretreatment and S2 pre-grafting modification steps and directly mixes and stirs all components evenly before discharging.

[0047] Performance verification: The initial test showed an antibacterial rate of 82.3% against Staphylococcus aureus, which was much lower than >99.99% in Example 1; after 500 wipes with 75% alcohol, the antibacterial rate dropped to 31.7%, and the antibacterial effect was severely weakened, making it impossible to achieve long-term antibacterial effect.

[0048] Comparative Example 3 (Industry-standard high-addition control group) This comparative example provides a commercially available ordinary zinc ion antibacterial nitrocellulose coating agent, which uses a physical blending method to add 3% pure zinc ion antibacterial powder (the amount added is 30 times that of Example 1).

[0049] Performance verification: The initial antibacterial rate was 95.1%, which is still lower than >99.99% in Example 1; the film felt rough to the touch, covered the texture of genuine leather, and the bending resistance decreased. After 500 bends, the coating showed slight cracking, and the raw material cost was more than 20 times that of Example 1.

[0050] Comparative Example 4 (Control group with addition below the lower limit) This comparative example provides a low-addition antibacterial coating agent with the same formulation as Example 1, except that the amount of 10% zinc nucleus aqueous dispersion added is adjusted to 0.5 parts (corresponding to a pure zinc nucleus solid content of 0.05%), and the preparation method is the same as that of Example 1.

[0051] Performance verification: The test results showed that the antibacterial rate against Staphylococcus aureus was 92.5%, which could not consistently reach the industry functional standard of over 99% and did not meet the needs of high-end scenarios.

Claims

1. A green antibacterial and detoxifying modified nitrocellulose leather finishing agent, characterized in that, It consists of the following components in a total of 100 parts by weight: 25-40 parts of water-based nitrocellulose emulsion; 0.8-1.2 parts of a 10% solids content aqueous dispersion of a zinc-based antibacterial modifier; 3-8 parts of film-forming aid; 0.5-2 parts of wetting and dispersing agent; 2-6 parts of film-forming regulator; The remainder is deionized water; The zinc-based antibacterial modifier is a surface-hydroxylated activated nano-zinc-based composite antibacterial powder with a particle size of 150-3000 nm and an elemental zinc content of ≥99%. The zinc-based antibacterial modifier is formed by etherification grafting of surface-active hydroxyl groups onto the active hydroxyl groups of the nitrocellulose molecular chains in the aqueous nitrocellulose emulsion, creating a chemically bonded modified nitrocellulose film-forming matrix. In the modified nitrocellulose leather agent, the solid content of the zinc-core antibacterial modifier is 0.08%-0.12%.

2. The green antibacterial and detoxifying modified nitrocellulose leather finishing agent according to claim 1, characterized in that, The amount of the 10% solid content of the zinc-core antibacterial modifier aqueous dispersion added is 1 part, and the solid content of the zinc-core antibacterial modifier in the modified nitrocellulose leather agent is 0.01-0.5%.

3. The green antibacterial and detoxifying modified nitrocellulose leather finishing agent according to claim 1, characterized in that, The aqueous nitrocellulose emulsion is a low-nitrogen aqueous nitrocellulose emulsion specifically for leather finishing, with a nitrogen content of 11.5%-12.2% and a nitrocellulose solid content of 28%-32%.

4. The green antibacterial and detoxifying modified nitrocellulose leather finishing agent according to claim 1, characterized in that, The film-forming aid is isooctyl acetate, the wetting and dispersing agent is tridecyl alcohol ethoxylate, and the film-forming regulator is isopropanol.

5. The green antibacterial and detoxifying modified nitrocellulose leather finishing agent according to claim 1, characterized in that, It also includes 0.1-1 parts of functional additives, wherein the functional additives are one or more of defoamers, leveling agents, and pH adjusters.

6. A method for preparing the green antibacterial and detoxifying modified nitrocellulose leather finishing agent according to any one of claims 1-5, characterized in that, Includes the following steps: S1, prepare an aqueous dispersion of the zinc-containing antibacterial modifier; S2, Activation pretreatment of Zhongke zinc core antibacterial modifier: Mix 10% solid content Zhongke zinc core antibacterial modifier aqueous dispersion with 10%-20% deionized water by total mass, add wetting and dispersing agent, and obtain a uniformly dispersed predispersant by low-speed stirring and ultrasonic treatment; adjust the pH of the predispersant to 8.5-9.5 with pH adjuster, heat to 50-60℃ and stir for 30-60 min to complete the activation of hydroxyl groups on the powder surface, and obtain activated zinc core dispersion; S3, Zinc Core-Nitrocellulose Pre-graft Modification: Add aqueous nitrocellulose emulsion to a reaction vessel, heat to 55-65℃, and slowly add the activated zinc core dispersion prepared in S2 to the nitrocellulose emulsion under low-speed stirring at 800-1200 rpm for 30-60 min. After the addition is complete, keep the mixture warm and stir for 2-4 h to allow the activated zinc core and nitrocellulose molecular chains to complete the etherification grafting reaction, thus obtaining zinc core modified nitrocellulose base material. S4, Coating agent compounding and molding: Add film-forming aid and film-forming regulator to the zinc core modified nitrocellulose base material prepared in S3, and stir at 1500-2500 rpm for 20-40 min; add the remaining deionized water to adjust the solid content of the system to 25%-35%, add optional functional additives, stir evenly, and filter through a 200-mesh filter to obtain the green antibacterial and detoxifying modified nitrocellulose leather agent.

7. The preparation method according to claim 6, characterized in that, The low-speed stirring in S2 has a rotation speed of 1500-2000 rpm and a stirring time of 10-20 min; the ultrasonic treatment has a power of 300-500 W and a treatment time of 15-30 min.

8. The preparation method according to claim 6, characterized in that, The etherification grafting reaction described in S3 is held at a temperature of 60°C for 3 hours.

9. The application of the green antibacterial and detoxifying modified nitrocellulose leather finishing agent according to any one of claims 1-5 in the production of leather products, characterized in that, The coating agent is used for top coating treatment of leather products.

10. The application according to claim 9, characterized in that, In the topcoat treatment process, roller coating, spraying, curtain coating or hand coating processes are used for application, with 1-2 coats. After application, the film is dried at room temperature without the need for UV curing and post-treatment is allowed.