Anionic antibacterial and aldehyde-removing leather finishing agent and preparation method thereof

Abstract

This invention discloses a negative ion antibacterial and formaldehyde-removing leather coating agent and its preparation method, belonging to the field of leather coating agent technology. It can achieve a synergistic effect of three functions: negative ion release, antibacterial, and formaldehyde removal. Based on a multi-level spiky core-shell structure, the effective contact area between tourmaline and air is greatly increased, which can efficiently release negative air ions and optimize the air quality of the environment. At the same time, a dual antibacterial system is constructed, in which zinc-based MOF slow-release zinc ions destroy the bacterial cell structure and tourmaline releases negative ions to oxidize and inhibit bacteria, achieving a broad-spectrum, efficient, and long-lasting antibacterial effect against common pathogenic bacteria such as Escherichia coli and Staphylococcus aureus. In addition, relying on the rich porous structure of zinc-based MOF, formaldehyde molecules are efficiently enriched and adsorbed. Combined with the catalytic oxidation and decomposition of formaldehyde by the negative ions continuously released by tourmaline, a long-lasting formaldehyde purification effect is achieved, which completely solves the technical defects of traditional adsorption materials that are easy to adsorb saturate and release formaldehyde twice.

Description

Technical Field

[0001] This invention belongs to the field of leather finishing agent technology, specifically a negative ion antibacterial and formaldehyde-removing leather finishing agent and its preparation method. Background Technology

[0002] Leather finishing agents are key functional materials in the leather processing. By forming a uniform film on the leather surface, they not only improve the leather's appearance and texture, and enhance its basic properties such as abrasion resistance and water resistance, but also endow the leather with additional functional characteristics. Their performance directly determines the quality, lifespan, and application range of leather products. With the improvement of people's living standards and the increasing awareness of health and environmental protection, traditional leather finishing agents with only decorative and basic protective functions can no longer meet market demands. Composite leather finishing agents that combine health, environmental protection, and multiple functions have become the core trend of industry development, especially in areas that come into close contact with the human body, such as automotive interiors, home sofas, and personal leather goods, where the demand for antibacterial and air-purifying functions of leather is even more urgent.

[0003] Leather products have porous surfaces that easily absorb moisture and organic matter, making them ideal breeding grounds for bacteria, mold, and other microorganisms. The proliferation of microorganisms can not only cause mold and odors in leather, affecting its appearance and lifespan, but may also harm human health through contact. Therefore, antibacterial properties have become one of the important evaluation indicators for leather coatings.

[0004] Currently, single inorganic antibacterial agents have drawbacks such as narrow antibacterial spectrum, slow onset of action, and easy development of drug resistance in microorganisms with long-term use. In addition, antibacterial agents also have problems such as poor compatibility with water-based resins and easy aggregation, which cannot achieve long-term and stable antibacterial effects and are difficult to meet the use needs of leather products such as automotive leather and furniture leather that are in long-term contact with the human body and are prone to bacterial growth. Summary of the Invention

[0005] The purpose of this invention is to provide a negative ion antibacterial and formaldehyde-removing leather coating agent that achieves a synergistic effect of negative ion release, antibacterial, and formaldehyde removal. Based on a multi-level spiky core-shell structure, the effective contact area between tourmaline and air is significantly increased, enabling efficient and sustained release of negative air ions to continuously settle inhalable particulate matter in the surrounding environment of the leather, thus optimizing the air quality of the usage environment. Simultaneously, a dual antibacterial system is constructed, combining the slow-release of zinc ions from zinc-based MOF to disrupt bacterial structure with the release of negative ions from tourmaline for oxidation and antibacterial effects, achieving broad-spectrum, efficient, and long-lasting antibacterial effects against common pathogenic bacteria such as Escherichia coli and Staphylococcus aureus. Furthermore, relying on the rich porous structure of zinc-based MOF to efficiently enrich and adsorb formaldehyde molecules, combined with the catalytic oxidation and decomposition of formaldehyde by the continuously released negative ions from tourmaline, a long-lasting formaldehyde purification effect is achieved, completely solving the technical defects of traditional adsorption materials that are prone to adsorption saturation and secondary formaldehyde release.

[0006] The objective of this invention can be achieved through the following technical solutions: A negative ion antibacterial and formaldehyde-removing leather finishing agent, comprising the following components by weight: 30-40 parts waterborne polyurethane resin, 5-10 parts negative ion antibacterial film-forming aid, 15-20 parts waterborne acrylic resin, 3-5 parts ultraviolet absorber UV-326, 2-3 parts hindered amine light stabilizer, 1-2 parts antioxidant 1010, 4-5 parts PE wax emulsion, 2-3 parts isomeric alcohol ether and 15-20 parts deionized water.

[0007] Furthermore, the specific preparation steps of the negative ion antibacterial film-forming aid are as follows: Step 1: Using hexadecyltrimethylammonium bromide as a template and urea as a structure regulator, a silica shell is generated in situ on the surface of tourmaline by hydrolysis and condensation of tetraethyl orthosilicate. The spiky core-shell structure of tourmaline is then constructed through a hydrothermal reaction to obtain spiky core-shell tourmaline.

[0008] Step 2: Using 2,5-dihydroxyterephthalic acid as a ligand and zinc nitrate as a metal source, zinc-based MOFs are grown in situ on the surface of spiky core-shell tourmaline to form a multi-level spiky composite structure, thus obtaining multi-level spiky core-shell tourmaline.

[0009] Step 3: Silane coupling modification of multi-level spiky core-shell tourmaline is carried out using γ-mercaptopropyltriethoxysilane to introduce thiol active groups on its surface, thereby obtaining modified multi-level spiky core-shell tourmaline.

[0010] Step 4: Under nitrogen protection, using triethylamine as a catalyst, modified multi-level spiky core-shell tourmaline and glycidyl methacrylate undergo a Michael addition reaction to obtain an anionic antibacterial film-forming aid.

[0011] Furthermore, the specific preparation steps for spiny core-shell tourmaline are as follows: Hexadecyltrimethylammonium bromide, urea, tourmaline, and deionized water were added to a reaction vessel and stirred for 30-40 minutes at 20-25°C and 500-600 r / min. Then, isopropanol and tetraethyl orthosilicate were added, and stirring was continued for 30-50 minutes. The mixture was heated to 70-80°C and reacted for 16-18 hours. The mixture was then filtered, and the filter cake was washed 2-4 times with deionized water and dried under vacuum at 60-80°C for 1-2 hours to obtain spiny core-shell tourmaline.

[0012] Furthermore, the ratio of hexadecyltrimethylammonium bromide, urea, tourmaline, deionized water, isopropanol, and tetraethyl orthosilicate is 80-90g: 40-44g: 32-40g: 450-500mL: 16-18mL: 4-6mL.

[0013] Furthermore, the specific preparation steps for multi-level spiny core-shell tourmaline are as follows: 2,5-Dihydroxyterephthalic acid, spiny core-shell tourmaline, sodium hydroxide, and deionized water were added to a reaction vessel and stirred for 20-30 minutes at 25-25℃ and 500-600 r / min. Then zinc nitrate hexahydrate was added, and the mixture was heated to 120-130℃ and stirred for 2-4 hours. The mixture was then centrifuged at 10000-12000 r / min for 3-5 minutes, and the precipitate was collected. The precipitate was washed 2-4 times with deionized water and dried under vacuum at 60-70℃ for 1-2 hours to obtain multi-stage spiny core-shell tourmaline.

[0014] Furthermore, the ratio of 2,5-dihydroxyterephthalic acid, spiny core-shell tourmaline, sodium hydroxide, deionized water, and zinc nitrate hexahydrate is 27-29g: 20-30g: 2-3g: 500-600mL: 12-14g.

[0015] Furthermore, the specific preparation steps for modified multi-level spiny core-shell tourmaline are as follows: Multi-level spiny core-shell tourmaline, anhydrous ethanol, and deionized water were added to a reaction vessel and stirred for 10 min at 50-60℃ and 500-600 r / min. Then, γ-mercaptopropyltriethoxysilane was added, and the pH was adjusted to 3-4 with hydrochloric acid solution. The reaction was continued with stirring for 6-7 h. After filtration, the precipitate was washed 2-4 times with deionized water and anhydrous ethanol and dried under vacuum at 60-80℃ for 1-2 h to obtain modified multi-level spiny core-shell tourmaline.

[0016] Furthermore, the ratio of multi-level spiny core-shell tourmaline, anhydrous ethanol, deionized water, and γ-mercaptopropyltriethoxysilane is 15-18g:3-4L:1-2L:100-110mL.

[0017] Furthermore, the specific preparation steps of the negative ion antibacterial film-forming aid are as follows: Modified multi-level spiky core-shell tourmaline, triethylamine, and N,N-dimethylformamide were added to a reaction vessel and stirred for 20-30 min under nitrogen protection, at 20-25℃ and 500-600 r / min. Then, glycidyl methacrylate was added, and the reaction was continued for 3-4 h. The unreacted monomers were removed by rotary evaporation, and deionized water was added. The mixture was sheared and stirred for 10-12 min at 10000-11000 r / min to obtain a negative ion antibacterial film-forming aid.

[0018] Furthermore, the ratio of modified multi-level spiny core-shell tourmaline, triethylamine, N,N-dimethylformamide and glycidyl methacrylate is 8-10g:0.10-0.12g:100-110mL:24-26g:120-140mL.

[0019] Furthermore, the specific preparation steps of the negative ion antibacterial and formaldehyde-removing leather coating agent are as follows: A waterborne polyurethane resin, a negative ion antibacterial film-forming aid, a waterborne acrylic resin, a UV absorber UV-326, a hindered amine light stabilizer, an antioxidant 1010, a PE wax emulsion, an isomeric alcohol ether, and deionized water are stirred at 20-25℃ and 500-600 r / min for 20-30 min to obtain a negative ion antibacterial formaldehyde-removing leather coating agent.

[0020] The beneficial effects of this invention are: 1. The negative ion antibacterial and formaldehyde-removing leather coating agent prepared by this invention can achieve a synergistic effect of three functions: negative ion release, antibacterial, and formaldehyde removal. Based on a multi-level spiky core-shell structure, the effective contact area between tourmaline and air is greatly increased, which can efficiently and persistently release negative air ions, continuously settle inhalable particulate matter in the surrounding environment of the leather, and optimize the air quality of the usage environment. At the same time, a dual antibacterial system is constructed, in which zinc-based MOF slow-release zinc ions destroy the bacterial cell structure and tourmaline releases negative ions to oxidize and inhibit bacteria, achieving a broad-spectrum, efficient, and long-lasting antibacterial effect against common pathogenic bacteria such as Escherichia coli and Staphylococcus aureus. In addition, relying on the rich porous structure of zinc-based MOF, formaldehyde molecules are efficiently enriched and adsorbed, and combined with the catalytic oxidation and decomposition of formaldehyde by the negative ions continuously released by tourmaline, a long-lasting formaldehyde purification effect is achieved, which completely solves the technical defects of traditional adsorption materials that are easy to adsorb saturate and release formaldehyde twice.

[0021] 2. This invention, based on the aforementioned modified multi-level spiky core-shell tourmaline, prepares a negative ion antibacterial film-forming aid through a grafting reaction with glycidyl methacrylate. This introduces epoxy functional groups that can bond with waterborne resin matrices onto the surface of the inorganic powder, fundamentally solving the industry pain point of poor interfacial compatibility and easy agglomeration and sedimentation between inorganic tourmaline powder and waterborne polyurethane or acrylic resin matrices. The modified functional powder can be uniformly dispersed in waterborne resin systems without agglomeration, ensuring not only the storage stability and film smoothness of the coating agent but also significantly improving the interfacial adhesion between the coating layer and the leather substrate, endowing the coating agent with excellent film-forming properties and long-term stability.

[0022] 3. This invention differs from existing technologies that involve simple physical blending of inorganic fillers and functional components. It first constructs a spiky silica core-shell layer on the tourmaline surface through the hydrolysis of tetraethyl orthosilicate, and then grows zinc-based MOF crystals in situ on the core-shell layer surface, successfully preparing modified multi-level spiky core-shell tourmaline. This achieves precise control of multi-level morphology from micrometer to nanometer scale, significantly increasing the specific surface area and the number of active sites, effectively solving the core defects of single tourmaline powder, such as few active sites and weak adsorption performance. This special multi-level structure, when applied to leather finishing agents, achieves dual technical effects: firstly, the ball-bearing lubrication effect of the core-shell structure reduces the increased friction on the leather surface caused by the introduction of inorganic fillers, allowing the leather to maintain excellent softness and smooth feel after finishing; secondly, it enhances the anchoring effect of the finishing agent on the leather surface, significantly improving the fracture toughness of the finishing layer and avoiding problems such as powdering and peeling of the finishing layer during long-term use. Attached Figure Description

[0023] Figure 1 This is a SEM image of the negative ion antibacterial film-forming aid in Example 3. Detailed Implementation

[0024] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0025] Example 1: A method for preparing a negative ion antibacterial and formaldehyde-removing leather coating agent, comprising the following steps: S1: Add 80g hexadecyltrimethylammonium bromide, 40g urea, 32g tourmaline and 450mL deionized water to a reaction vessel, stir for 30min at 20℃ and 500r / min, then add 16mL isopropanol and 4mL tetraethyl orthosilicate, continue stirring for 30min, heat to 70℃, continue the reaction for 16h, filter, wash the filter cake twice with deionized water, and vacuum dry at 60℃ for 1h to obtain spiky core-shell tourmaline.

[0026] S2: Add 27g of 2,5-dihydroxyterephthalic acid, 20g of spiny core-shell tourmaline, 2g of sodium hydroxide and 500mL of deionized water to a reaction vessel, stir for 20min at 25℃ and 500r / min, then add 12g of zinc nitrate hexahydrate, heat to 120℃, continue stirring for 2h, centrifuge at 10000r / min for 3min, collect the precipitate, wash the precipitate twice with deionized water, and vacuum dry at 60℃ for 1h to obtain multi-stage spiny core-shell tourmaline.

[0027] S3: Add 15g of multi-level spiky core-shell tourmaline, 3L of anhydrous ethanol and 1L of deionized water to a reaction vessel, stir for 10min at 50℃ and 500r / min, then add 100mL of γ-mercaptopropyltriethoxysilane, adjust the pH to 3 with hydrochloric acid solution, continue stirring for 6h, filter, wash the precipitate twice with deionized water and anhydrous ethanol, and vacuum dry at 60℃ for 1h to obtain modified multi-level spiky core-shell tourmaline.

[0028] S4: Add 8g of modified multi-level spiky core-shell tourmaline, 0.10g of triethylamine and 100mL of N,N-dimethylformamide to a reaction vessel. Stir for 20min under nitrogen protection, 20℃ and 500r / min. Then add 24g of glycidyl methacrylate and continue the reaction for 3h. Remove unreacted monomers by rotary evaporation. Add 120mL of deionized water and shear and stir for 10min at 10000r / min to obtain the negative ion antibacterial film-forming aid.

[0029] S5: Mix 30g of waterborne polyurethane resin, 5g of negative ion antibacterial film-forming aid, 15g of waterborne acrylic resin, 3g of ultraviolet absorber UV-326, 2g of hindered amine light stabilizer, 1g of antioxidant 1010, 4g of PE wax emulsion, 2g of isomeric alcohol ether and 15g of deionized water at 20℃ and 500r / min for 20min to obtain a negative ion antibacterial formaldehyde-removing leather coating agent.

[0030] Example 2: A method for preparing a negative ion antibacterial and formaldehyde-removing leather coating agent, comprising the following steps: S1: Add 85g hexadecyltrimethylammonium bromide, 42g urea, 36g tourmaline and 475mL deionized water to a reaction vessel and stir for 35min at 22.5℃ and 550r / min. Then add 17mL isopropanol and 5mL tetraethyl orthosilicate and continue stirring for 40min. Heat to 75℃ and continue the reaction for 17h. Filter and wash the filter cake three times with deionized water. Dry under vacuum at 70℃ for 1.5h to obtain spiny core-shell tourmaline.

[0031] S2: Add 28g of 2,5-dihydroxyterephthalic acid, 25g of spiny core-shell tourmaline, 2.5g of sodium hydroxide and 550mL of deionized water to a reaction vessel, stir for 25min at 25℃ and 550r / min, then add 13g of zinc nitrate hexahydrate, heat to 125℃, continue stirring for 3h, centrifuge at 11000r / min for 4min, collect the precipitate, wash the precipitate 3 times with deionized water, and vacuum dry at 65℃ for 1.5h to obtain multi-stage spiny core-shell tourmaline.

[0032] S3: 16.5g of multi-level spiky core-shell tourmaline, 3.5L of anhydrous ethanol and 1.5L of deionized water were added to a reaction vessel and stirred for 10min at 55℃ and 550r / min. Then, 105mL of γ-mercaptopropyltriethoxysilane was added, and the pH was adjusted to 3.5 with hydrochloric acid solution. The reaction was continued to be stirred for 6.5h. After filtration, the precipitate was washed three times with deionized water and anhydrous ethanol and dried under vacuum at 70℃ for 1.5h to obtain modified multi-level spiky core-shell tourmaline.

[0033] S4: 9g of modified multi-level spiky core-shell tourmaline, 0.11g of triethylamine and 105mL of N,N-dimethylformamide were added to a reaction vessel and stirred for 25min under nitrogen protection, 22.5℃ and 550r / min. Then 25g of glycidyl methacrylate was added and the reaction was continued for 3.5h. The unreacted monomers were removed by rotary evaporation. 130mL of deionized water was added and the mixture was sheared and stirred for 11min at 10500r / min to obtain the negative ion antibacterial film-forming aid.

[0034] S5: 35g of waterborne polyurethane resin, 7.5g of negative ion antibacterial film-forming aid, 17.5g of waterborne acrylic resin, 4g of ultraviolet absorber UV-326, 2.5g of hindered amine light stabilizer, 1.5g of antioxidant 1010, 4.5g of PE wax emulsion, 2.5g of isomeric alcohol ether and 17.5g of deionized water are stirred at 22.5℃ and 550r / min for 25min to obtain a negative ion antibacterial formaldehyde-removing leather coating agent.

[0035] Example 3: A method for preparing a negative ion antibacterial and formaldehyde-removing leather coating agent, comprising the following steps: S1: Add 90g hexadecyltrimethylammonium bromide, 44g urea, 40g tourmaline and 500mL deionized water to a reaction vessel, stir for 40min at 25℃ and 600r / min, then add 18mL isopropanol and 6mL tetraethyl orthosilicate, continue stirring for 50min, heat to 80℃, continue the reaction for 18h, filter, wash the filter cake 4 times with deionized water, and vacuum dry at 80℃ for 2h to obtain spiny core-shell tourmaline.

[0036] S2: Add 29g of 2,5-dihydroxyterephthalic acid, 30g of spiny core-shell tourmaline, 3g of sodium hydroxide and 600mL of deionized water to a reaction vessel, stir for 30min at 25℃ and 600r / min, then add 14g of zinc nitrate hexahydrate, heat to 130℃, continue stirring for 4h, centrifuge at 12000r / min for 5min, collect the precipitate, wash the precipitate 4 times with deionized water, and vacuum dry at 70℃ for 2h to obtain multi-stage spiny core-shell tourmaline.

[0037] S3: 18g of multi-level spiky core-shell tourmaline, 4L of anhydrous ethanol and 2L of deionized water were added to a reaction vessel and stirred for 10min at 60℃ and 600r / min. Then 110mL of γ-mercaptopropyltriethoxysilane was added, and the pH was adjusted to 4 with hydrochloric acid solution. The reaction was continued to be stirred for 7h. After filtration, the precipitate was washed 4 times with deionized water and anhydrous ethanol and dried under vacuum at 80℃ for 2h to obtain modified multi-level spiky core-shell tourmaline.

[0038] S4: 10g of modified multi-level spiky core-shell tourmaline, 0.12g of triethylamine and 110mL of N,N-dimethylformamide were added to a reaction vessel and stirred for 30min under nitrogen protection, 25℃ and 600r / min. Then 26g of glycidyl methacrylate was added and the reaction was continued for 4h. The unreacted monomers were removed by rotary evaporation. 140mL of deionized water was added and sheared and stirred for 12min at 11000r / min to obtain the negative ion antibacterial film-forming aid.

[0039] S5: Mix 40g of waterborne polyurethane resin, 10g of negative ion antibacterial film-forming aid, 20g of waterborne acrylic resin, 5g of ultraviolet absorber UV-326, 3g of hindered amine light stabilizer, 2g of antioxidant 1010, 5g of PE wax emulsion, 3g of isomeric alcohol ether and 20g of deionized water at 25℃ and 600r / min for 30min to obtain a negative ion antibacterial formaldehyde-removing leather coating agent.

[0040] Comparative Example 1: Based on Example 3, the spiky core-shell tourmaline in step S2 was replaced with the raw tourmaline in step S1.

[0041] Comparative Example 2: Based on Example 3, the multi-level spiky core-shell tourmaline in step S3 was replaced with the spiky core-shell tourmaline prepared in step S1.

[0042] Comparative Example 3: Based on Example 3, the negative ion antibacterial film-forming aid in step S5 was replaced with the modified multi-level spiky core-shell tourmaline prepared in step S3.

[0043] Performance tests were conducted on Examples 1-3 and Comparative Examples 1-3. The negative ion antibacterial and formaldehyde-removing leather finishing agent was applied to white cowhide blanks, and performance tests were performed. The hiding power (comparative ratio) test was conducted using a hiding power tester according to GB / T [standard / standard]. According to standard 23981-2009, higher values ​​indicate stronger hiding power; the number of spraying times required for complete coverage is tested by spraying layers onto a standard leather blank until the base color difference and defects are no longer visible to the naked eye, and the number of spraying times is recorded; UV yellowing resistance test: using a QUV accelerated aging test chamber (UVA-340 lamp), after irradiation for 168 hours, the change is measured using a colorimeter, and the lower the value, the better the yellowing resistance; heat yellowing resistance: the sample is placed in a 120℃ oven for 72 hours, and measured after cooling; hand feel score: the average score is obtained by blind evaluation by 5 experienced leather engineers, with 10 points being the best (soft, smooth, natural); abrasion resistance: according to QB / T2726-2005 standard, using a Taber abrasion tester with a 500g load, the number of revolutions when the base material is exposed is recorded; negative ion release is tested according to GB / T 28628-2012 standard; antibacterial rate of Escherichia coli and antibacterial rate of Staphylococcus aureus are tested according to GB / T The formaldehyde removal rate was tested according to the standard GB / T 21866-2008, and the 24-hour formaldehyde removal rate was tested according to the standard GB / T 23761-2020. The results are shown in Table 1. Table 1

[0044] As shown in Table 1, the original tourmaline in Comparative Example 1 has a smooth surface and a very low specific surface area, which cannot provide uniform growth sites for zinc-based MOFs. This results in a large amount of zinc-based MOF crystal agglomeration and extremely low loading, making it impossible to form a multi-level spiky core-shell structure. Without the buffering and lubricating effect of the spiky silica core-shell layer, the original tourmaline powder has high hardness and poor compatibility with resin, resulting in a rough leather feel after coating and a significant increase in friction. It is also very easy to peel off after long-term use. Without the protection of the silica core-shell layer for tourmaline, the powder is prone to agglomeration in the resin, leading to uneven UV absorption and thermal stability.

[0045] In Comparative Example 2, the antibacterial and formaldehyde removal functions were basically lost. Zinc-based MOF is the core carrier for achieving antibacterial and formaldehyde removal in this invention. Without the zinc-based MOF layer, there is no slow-release bactericidal effect of zinc ions. Relying only on the weak antibacterial effect of tourmaline negative ions, the antibacterial rate of Escherichia coli and Staphylococcus aureus is insufficient. At the same time, without the rich porous structure of zinc-based MOF, it is impossible to physically adsorb and enrich formaldehyde. Relying only on the weak oxidative decomposition of tourmaline negative ions, the formaldehyde removal rate in 24 hours is insufficient and the purification effect cannot be achieved. Without the multi-level spiky structure of zinc-based MOF, the specific surface area of ​​the material decreases, the effective contact area between tourmaline and air is greatly reduced, and the amount of negative ions released only decreases, making it impossible to achieve long-lasting and efficient negative ion release.

[0046] Although Comparative Example 3 retained the complete multi-level spiky core-shell tourmaline structure, it did not introduce epoxy functional groups that are compatible with waterborne polyurethane and acrylic resins through glycidyl methacrylate grafting. The silane-modified thiol groups alone could not achieve compatibility with the resin, resulting in severe agglomeration of the powder in the waterborne system. The ungrafted powder could not form chemical bonds with the resin, and it was only a simple physical blending, resulting in an uneven coating film with a rough and poor smoothness, which completely failed to meet the requirements for leather finishing.

[0047] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the invention.

Claims

1. A negative ion antibacterial and formaldehyde-removing leather coating agent, characterized in that, By mass, it includes the following components: 30-40 parts waterborne polyurethane resin, 5-10 parts negative ion antibacterial film-forming aid, 15-20 parts waterborne acrylic resin, 3-5 parts ultraviolet absorber UV-326, 2-3 parts hindered amine light stabilizer, 1-2 parts antioxidant 1010, 4-5 parts PE wax emulsion, 2-3 parts isomeric alcohol ether and 15-20 parts deionized water; The ionic antibacterial film-forming aid is obtained by Michael addition reaction of modified multi-level spiky core-shell tourmaline with glycidyl methacrylate.

2. The negative ion antibacterial and formaldehyde-removing leather coating agent according to claim 1, characterized in that, The specific preparation steps for the modified multi-level spiky core-shell tourmaline are as follows: Step 1: Using hexadecyltrimethylammonium bromide as a template and urea as a structure regulator, a silica shell is generated in situ on the surface of tourmaline by hydrolysis and condensation of tetraethyl orthosilicate. The spiky core-shell structure of tourmaline is then constructed by hydrothermal reaction to obtain spiky core-shell tourmaline. Step 2: Using 2,5-dihydroxyterephthalic acid as a ligand and zinc nitrate as a metal source, zinc-based MOFs are grown in situ on the surface of spiky core-shell tourmaline to form a multi-level spiky composite structure, thus obtaining multi-level spiky core-shell tourmaline. Step 3: Silane coupling modification of multi-level spiky core-shell tourmaline is carried out using γ-mercaptopropyltriethoxysilane to introduce thiol active groups on its surface, thereby obtaining modified multi-level spiky core-shell tourmaline.

3. The negative ion antibacterial and formaldehyde-removing leather coating agent according to claim 2, characterized in that, The specific preparation steps for the spiny core-shell tourmaline are as follows: Hexadecyltrimethylammonium bromide, urea, tourmaline, and deionized water were added to a reaction vessel and stirred for 30-40 minutes at 20-25°C and 500-600 r / min. Then, isopropanol and tetraethyl orthosilicate were added, and stirring was continued for 30-50 minutes. The mixture was heated to 70-80°C and reacted for 16-18 hours. The mixture was then filtered, and the filter cake was washed 2-4 times with deionized water and dried under vacuum at 60-80°C for 1-2 hours to obtain spiny core-shell tourmaline.

4. The negative ion antibacterial and formaldehyde-removing leather coating agent according to claim 3, characterized in that, The ratio of hexadecyltrimethylammonium bromide, urea, tourmaline, deionized water, isopropanol and tetraethyl orthosilicate is 80-90g: 40-44g: 32-40g: 450-500mL: 16-18mL: 4-6mL.

5. The negative ion antibacterial and formaldehyde-removing leather coating agent according to claim 2, characterized in that, The specific preparation steps for the multi-level spiky core-shell tourmaline are as follows: 2,5-Dihydroxyterephthalic acid, spiny core-shell tourmaline, sodium hydroxide, and deionized water were added to a reaction vessel and stirred for 20-30 minutes at 25-25℃ and 500-600 r / min. Then zinc nitrate hexahydrate was added, and the mixture was heated to 120-130℃ and stirred for 2-4 hours. The mixture was then centrifuged at 10000-12000 r / min for 3-5 minutes, and the precipitate was collected. The precipitate was washed 2-4 times with deionized water and dried under vacuum at 60-70℃ for 1-2 hours to obtain multi-stage spiny core-shell tourmaline. The ratio of 2,5-dihydroxyterephthalic acid, spiny core-shell tourmaline, sodium hydroxide, deionized water, and zinc nitrate hexahydrate is 27-29g: 20-30g: 2-3g: 500-600mL: 12-14g.

6. The negative ion antibacterial and formaldehyde-removing leather coating agent according to claim 2, characterized in that, The specific preparation steps for the modified multi-level spiky core-shell tourmaline are as follows: Multi-level spiny core-shell tourmaline, anhydrous ethanol, and deionized water were added to a reaction vessel and stirred for 10 min at 50-60℃ and 500-600 r / min. Then, γ-mercaptopropyltriethoxysilane was added, and the pH was adjusted to 3-4 with hydrochloric acid solution. The reaction was continued with stirring for 6-7 h. After filtration, the precipitate was washed 2-4 times with deionized water and anhydrous ethanol and dried under vacuum at 60-80℃ for 1-2 h to obtain modified multi-level spiny core-shell tourmaline.

7. The negative ion antibacterial and formaldehyde-removing leather coating agent according to claim 6, characterized in that, The ratio of the multi-level spiny core-shell tourmaline, anhydrous ethanol, deionized water and γ-mercaptopropyltriethoxysilane is 15-18g:3-4L:1-2L:100-110mL.

8. The negative ion antibacterial and formaldehyde-removing leather coating agent according to claim 2, characterized in that, The specific preparation steps of the negative ion antibacterial film-forming aid are as follows: Modified multi-level spiky core-shell tourmaline, triethylamine, and N,N-dimethylformamide were added to a reaction vessel and stirred for 20-30 min under nitrogen protection, at 20-25℃ and 500-600 r / min. Then, glycidyl methacrylate was added, and the reaction was continued for 3-4 h. The unreacted monomers were removed by rotary evaporation, and deionized water was added. The mixture was sheared and stirred for 10-12 min at 10000-11000 r / min to obtain a negative ion antibacterial film-forming aid.

9. The negative ion antibacterial and formaldehyde-removing leather coating agent according to claim 8, characterized in that, The ratio of the modified multi-level spiny core-shell tourmaline, triethylamine, N,N-dimethylformamide and glycidyl methacrylate is 8-10g:0.10-0.12g:100-110mL:24-26g:120-140mL.

10. The preparation method of a negative ion antibacterial and formaldehyde-removing leather coating agent according to claim 2, characterized in that, The specific preparation steps of the negative ion antibacterial and formaldehyde-removing leather coating agent are as follows: A waterborne polyurethane resin, a negative ion antibacterial film-forming aid, a waterborne acrylic resin, a UV absorber UV-326, a hindered amine light stabilizer, an antioxidant 1010, a PE wax emulsion, an isomeric alcohol ether, and deionized water are stirred at 20-25℃ and 500-600 r / min for 20-30 min to obtain a negative ion antibacterial formaldehyde-removing leather coating agent.

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