A long-lasting antibacterial agent for household paper, its preparation method and application

Abstract

This invention discloses a long-lasting antibacterial agent for household paper, its preparation method, and its application, belonging to the field of antibacterial agent technology. The antibacterial agent uses alkali lignin, zinc sulfate heptahydrate, and calcium-based montmorillonite as raw materials, and undergoes the following processes: 1) pretreatment; 2) aqueous phase complexation; 3) composite reaction; 4) spray drying and sieving; and 5) post-treatment, to obtain microspherical powder with a particle size of 10-50 μm. This invention pioneers a dynamic coordination bond between zinc and lignin, endowing the antibacterial agent with dry-state locking and wet-state release functions, breaking through the technical bottlenecks of uncontrollable release and poor long-lasting effect of traditional antibacterial agents. By constructing a montmorillonite core-shell composite structure, it achieves multiple synergistic effects of chemical sterilization, physical slow release, and paper strengthening, resulting in multiple effects from a single agent. Simultaneously, it transforms alkali lignin, a waste material from papermaking, into a high-value core component, realizing a shift from cost increment to value creation, possessing both superior performance and significant economic advantages.

Description

Technical Field

[0001] This invention relates to the field of antibacterial agent technology, and in particular to a long-lasting antibacterial agent for household paper, its preparation method, and its application. Background Technology

[0002] Household paper products, such as toilet paper, facial tissues, wet wipes, and kitchen paper towels, come into close contact with human skin in daily life. The humid environment and abundant nutrients in these paper products make them easy breeding grounds for bacteria (such as E. coli and Staphylococcus aureus), especially in public restrooms and kitchens. To improve hygiene and safety, various antibacterial household paper products have emerged on the market.

[0003] Currently, the antibacterial agents added to household paper mainly fall into the following categories: (1) Quaternary ammonium salt compounds, such as benzalkonium chloride, have a rapid bactericidal effect, but may cause skin irritation, and the antibacterial effect decays rapidly with use; (2) Inorganic antibacterial agents, such as nano silver and nano zinc oxide, have good long-lasting effects, but the safety of nanomaterials is controversial, and the cost is high; (3) Natural extracts, such as tea tree oil, have good safety but weak antibacterial strength, poor stability, and high cost; (4) Polyhexamethylene biguanide (PHMB) has a broad antibacterial spectrum and is relatively mild. It is a commonly used ingredient in high-end wet toilet paper, but its preparation cost is high, and its long-term environmental fate needs further research.

[0004] Furthermore, existing antibacterial agents are mostly added to paper through simple physical mixing or adsorption, which has problems such as easy dissolution, poor water resistance, and uncontrollable release behavior. In particular, an ideal antibacterial agent should be stable when paper is stored in a dry state, and should be able to release active ingredients rapidly when it comes into contact with water during use (wiping) to achieve "on-demand sterilization," but currently there is a lack of low-cost solutions that combine intelligent response and long-lasting effects.

[0005] On the other hand, the large amount of black liquor produced by the papermaking industry contains abundant alkali lignin, which is currently mainly used as low-value fuel or a substance requiring expensive environmental treatment. Developing high-value utilization and functional products from these industrial byproducts has significant economic and social benefits.

[0006] Therefore, developing an antibacterial agent for household paper that is low in raw material cost, has intelligent response release capability, and is long-lasting and safe has important practical significance and market value. Summary of the Invention

[0007] The purpose of this invention is to address the shortcomings of existing technologies by proposing a long-lasting antibacterial agent for household paper, its preparation method, and its application.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: This invention first proposes a long-lasting antibacterial agent for household paper, wherein the antibacterial agent is a lignin-zinc-montmorillonite composite antibacterial agent, comprising the following raw materials in parts by weight: 30-40 parts of alkali lignin, 30-40 parts of zinc sulfate heptahydrate, 18-32 parts of calcium-based montmorillonite, 4-8 parts of citric acid, and 120-160 parts of deionized water. The antibacterial agent is a microsphere powder with a particle size of 10-50 μm, which forms a zinc-lignin dynamic coordination bond structure inside and is loaded with a calcium-based montmorillonite layered structure on the outside.

[0009] Preferably, the alkali lignin is an industrial-grade product extracted from papermaking black liquor, with a purity ≥85%, and is pulverized and passed through an 80-mesh sieve; the zinc sulfate heptahydrate is agricultural-grade, with a purity ≥98%.

[0010] Preferably, the calcium-based montmorillonite has a fineness of 200 mesh and a moisture content of ≤5%; the mass ratio of alkali lignin to zinc sulfate heptahydrate is 1:1, and the amount of calcium-based montmorillonite added is 30% of the total raw material mass.

[0011] This invention also proposes a method for preparing the aforementioned long-lasting antibacterial agent for household paper, comprising the following steps: S1. Raw material pretreatment: alkali lignin is pulverized and passed through an 80-mesh sieve; calcium-based montmorillonite is dried at high temperature and then cooled to room temperature for later use. S2. Preparation of complexation reaction solution: Inject deionized water into a stirring tank, control the rotation speed at 150-200 rpm and the temperature at 25-55℃, add zinc sulfate heptahydrate to dissolve, then add alkali lignin powder and stir for 1.5-2.5 h, then add citric acid to adjust the pH to 5.0-5.5, and continue stirring for 20-40 min. Alkali lignin molecules contain numerous electron-rich groups such as phenolic hydroxyl groups, alcoholic hydroxyl groups, and carboxyl groups. Zinc sulfate heptahydrate dissociates into zinc ions (Zn²⁺) in aqueous solution. Under the heating and stirring conditions of step S2, the zinc ions coordinate with the oxygen-containing functional groups on lignin, forming stable coordinate bonds. The carboxyl groups of the added citric acid also participate in coordination, forming a ternary dynamic coordination network of "zinc ion-lignin / citric acid". This coordination bond has moderate strength and is not an irreversible covalent bond; its stability is affected by the ambient pH and water molecule concentration. S3, Composite reaction: Add pretreated calcium-based montmorillonite, maintain temperature and speed while stirring for 0.8-1.2 hours to obtain a mixed liquid; S4. Spray drying: The mixed liquid is fed into a spray dryer, and the inlet air temperature is controlled at 180-190℃, the outlet air temperature at 80-90℃, and the atomizer speed at 15000-18000rpm to obtain composite powder. Calcium-based montmorillonite, a natural layered silicate mineral, possesses a large specific surface area and ion exchange capacity. Pretreated montmorillonite is added to a complexing reaction solution. Under stirring, the lamellar structure of montmorillonite partially peels off and disperses, binding with the already formed zinc-lignin complex through electrostatic adsorption, hydrogen bonding, and physical coating. During spray drying, the droplets are instantly dried, and the montmorillonite lamellars recombine and solidify on and inside the microspheres, ultimately forming a microsphere structure with the zinc-lignin complex as the core and the montmorillonite lamellars as the shell. S5. Post-processing: The composite powder is classified by passing it through a three-layer vibrating sieve of 40-200 mesh, and the powder with a particle size of 10-50μm is collected. The finished product is obtained by vacuum nitrogen packaging.

[0012] Preferably, in S1, the drying temperature of calcium-based montmorillonite is 105°C and the drying time is 2 hours.

[0013] Preferably, in step S4, the feeding rate is 800-1000 kg / h.

[0014] Preferably, in step S5, the vacuum degree of the vacuum packaging is -0.09 to -0.1 MPa, and the nitrogen filling time is 10-15 seconds.

[0015] The present invention also proposes the application of the aforementioned long-lasting antibacterial agent for household paper in the production of household paper, wherein the antibacterial agent is applied to the production of household paper by means of internal addition or surface coating, and the amount of antibacterial agent added is 0.05-0.5% of the oven-dry pulp mass of the household paper; the household paper includes toilet paper, facial tissues, and kitchen paper.

[0016] When stored in a dry state, the low humidity and limited water molecules ensure the zinc ions are firmly locked within the dynamic coordination network, resulting in a very slow release rate and guaranteeing the long-lasting effectiveness of the antibacterial agent while preventing ineffective waste. When used in a wet state, such as when wiping skin or object surfaces with tissue paper, a large number of water molecules penetrate the microsphere structure upon contact with moisture. These water molecules compete with zinc ions for coordination, rapidly disrupting the original dynamic coordination bonds and causing a concentrated release of zinc ions within a short period, achieving an immediate and highly effective bactericidal concentration.

[0017] The outer montmorillonite shell forms a physical diffusion barrier for the release of zinc ions, prolonging the release time curve. During use, part of the surface montmorillonite layer is rubbed off, exposing the fresh antibacterial core underneath, achieving surface replacement and avoiding the problem of traditional coatings failing due to surface contamination.

[0018] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention designs a moisture-responsive intelligent release mechanism for antibacterial agents in household paper by constructing a dynamic coordination bond between zinc and lignin, thus resolving the contradiction between antibacterial efficiency and long-lasting effect in the prior art.

[0019] Existing technologies (such as quaternary ammonium salts, PHMB, or simple mixtures of inorganic salts) rely on physical adsorption or ion exchange. Their release behavior is static and passive. Either the initial release is too fast, leading to later failure, or the release rate is insufficient, affecting the immediate bactericidal effect.

[0020] In this invention, the dynamic coordination network formed by zinc ions and lignin / citric acid exhibits extremely sensitive bonding strength to water molecule concentration: when the paper is stored dry, the coordination bonds are stable, effectively locking in the release of zinc ions with minimal loss; upon contact with water during wiping, a large number of water molecules rapidly compete for coordination sites, triggering rapid dissociation of the coordination bonds and achieving an explosive release of zinc ions. This response mode ensures the stability of the antibacterial agent over a long shelf life and its high efficiency at critical moments of use, achieving a leap from continuous, slow release to precise, on-demand release.

[0021] 2. This invention constructs a long-lasting protective system combining chemical sterilization, physical barrier, and adsorption fixation through the layered structure of montmorillonite and the synergistic effect of multiple components, overcoming the shortcomings of existing technologies such as easy leaching, poor water resistance, and limited functionality. Existing antibacterial agents (such as coated quaternary ammonium salts) have weak binding force with fibers and are easily leached out by water, affecting durability and potentially causing excessive skin exposure. In the microsphere structure of this invention, the montmorillonite layers form a dense physical shell, acting as a slow-release barrier to prolong the action time curve of zinc ions; and as a strong adsorption matrix, anchoring the entire composite microsphere to the fiber surface through electrostatics and van der Waals forces, making it resistant to wiping and water washing. Furthermore, the phenolic antibacterial activity of lignin, the physical adsorption and isolation of bacteria by montmorillonite, and the bactericidal effect of zinc ions form a multi-target synergy, improving the broad spectrum and efficiency of antibacterial activity while reducing the irritation risk associated with relying solely on high-concentration chemical bactericides.

[0022] 3. This invention achieves revolutionary optimization of cost structure and product performance at the molecular level through the integrated design of industrial by-product resource utilization and antibacterial-enhancing dual functions. Existing technologies often require the addition of specialized and expensive chemically synthesized components (such as PHMB) to obtain antibacterial properties, which is purely an increase in cost.

[0023] This invention uses alkali lignin extracted from papermaking black liquor as its core raw material, transforming the burden of environmental treatment into the core value of the product and significantly reducing raw material costs. More importantly, lignin, as a natural polymer binder, and montmorillonite, as a nanosheet filler, not only impart antibacterial properties to paper but also bridge pulp fibers through hydrogen bonds and network filling, significantly improving the dry / wet tensile strength of the paper. This means that this invention is not a simple additive but a functional building block that achieves highly efficient and intelligent antibacterial properties while reducing or replacing the use of other reinforcing chemicals, achieving a dual breakthrough in economic benefits and product performance.

[0024] In summary, this invention pioneers a zinc-lignin dynamic coordination bond, endowing the antibacterial agent with dry-state locking and wet-state release capabilities, overcoming the technical bottlenecks of uncontrollable release and poor long-term effectiveness of traditional antibacterial agents. By constructing a montmorillonite core-shell composite structure, it achieves multiple synergistic effects of chemical sterilization, physical slow release, and paper strengthening, resulting in multiple benefits from a single agent. Simultaneously, it transforms alkali lignin, a waste material from papermaking, into a high-value core component, realizing a shift from cost increment to value creation, combining superior performance with significant economic advantages. Detailed Implementation

[0025] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with existing known technologies. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0026] Example 1: A long-lasting antibacterial agent for household paper, comprising the following raw materials in parts by weight: 30 kg of alkali lignin, 40 kg of zinc sulfate heptahydrate, 18 kg of calcium montmorillonite, 8 kg of citric acid, and 120 kg of deionized water; The antibacterial agent is a microsphere powder with a particle size of 10-50 μm, which forms a zinc-lignin dynamic coordination bond structure inside and is loaded with a calcium-based montmorillonite layered structure on the outside.

[0027] The alkali lignin is an industrial-grade product extracted from papermaking black liquor, with a purity ≥85%, and is processed by pulverizing and passing through an 80-mesh sieve; the zinc sulfate heptahydrate is agricultural-grade, with a purity ≥98%.

[0028] The fineness of the calcium-based montmorillonite is 200 mesh, and the moisture content is ≤5%; the mass ratio of alkali lignin to zinc sulfate heptahydrate is 1:1, and the amount of calcium-based montmorillonite added is 30% of the total raw material mass.

[0029] The preparation method of the long-lasting antibacterial agent for household paper includes the following steps: S1. Raw material pretreatment: alkali lignin is pulverized and passed through an 80-mesh sieve; calcium-based montmorillonite is dried at high temperature and then cooled to room temperature for later use. S2. Preparation of complexation reaction solution: Deionized water is injected into the stirring tank, the speed is controlled at 200 rpm and the temperature is 50-55℃. After zinc sulfate heptahydrate is added and dissolved, alkali lignin powder is added and stirred for 2 hours. Then citric acid is added and stirred for another 30 minutes. S3, Composite Reaction: Add pretreated calcium-based montmorillonite, maintain temperature and speed while stirring for 1 hour to obtain a mixed liquid; S4. Spray drying: The mixed liquid is fed into a spray dryer, and the inlet air temperature is controlled at 185℃, the outlet air temperature at 85℃, and the atomizer speed at 16000rpm to dry the composite powder. S5. Post-processing: The composite powder is classified by passing it through a three-layer vibrating sieve of 40-200 mesh, and the powder with a particle size of 10-50μm is collected. The powder is then vacuum-packed with nitrogen to obtain a long-lasting antibacterial agent for household paper.

[0030] In S1, the drying temperature of calcium-based montmorillonite is 105℃ and the drying time is 2h.

[0031] In S4, the feeding rate is 1000 kg / h.

[0032] In step S5, the vacuum degree of the vacuum packaging is -0.1 MPa, and the nitrogen filling time is 15 seconds.

[0033] Example 2: A long-lasting antibacterial agent for household paper, comprising the following raw materials in parts by weight: 35 kg of alkali lignin, 35 kg of zinc sulfate heptahydrate, 30 kg of calcium montmorillonite, 6 kg of citric acid, and 140 kg of deionized water; The antibacterial agent is a microsphere powder with a particle size of 10-50 μm, which forms a zinc-lignin dynamic coordination bond structure inside and is loaded with a calcium-based montmorillonite layered structure on the outside.

[0034] The alkali lignin is an industrial-grade product extracted from papermaking black liquor, with a purity ≥85%, and is processed by pulverizing and passing through an 80-mesh sieve; the zinc sulfate heptahydrate is agricultural-grade, with a purity ≥98%.

[0035] The fineness of the calcium-based montmorillonite is 200 mesh, and the moisture content is ≤5%; the mass ratio of alkali lignin to zinc sulfate heptahydrate is 1:1, and the amount of calcium-based montmorillonite added is 30% of the total raw material mass.

[0036] The preparation method of the long-lasting antibacterial agent for household paper includes the following steps: S1. Raw material pretreatment: alkali lignin is pulverized and passed through an 80-mesh sieve; calcium-based montmorillonite is dried at high temperature and then cooled to room temperature for later use. S2. Preparation of complexation reaction solution: Deionized water is injected into the stirring tank, the speed is controlled at 200 rpm and the temperature is 50-55℃. After zinc sulfate heptahydrate is added and dissolved, alkali lignin powder is added and stirred for 2 hours. Then citric acid is added and stirred for another 30 minutes. S3, Composite Reaction: Add pretreated calcium-based montmorillonite, maintain temperature and speed while stirring for 1 hour to obtain a mixed liquid; S4. Spray drying: The mixed liquid is fed into a spray dryer, and the inlet air temperature is controlled at 185℃, the outlet air temperature at 85℃, and the atomizer speed at 16000rpm to dry the composite powder. S5. Post-processing: The composite powder is classified by passing it through a three-layer vibrating sieve of 40-200 mesh, and the powder with a particle size of 10-50μm is collected. The powder is then vacuum-packed with nitrogen to obtain a long-lasting antibacterial agent for household paper.

[0037] In S1, the drying temperature of calcium-based montmorillonite is 105℃ and the drying time is 2h.

[0038] In S4, the feeding rate is 900 kg / h.

[0039] In step S5, the vacuum degree of the vacuum packaging is -0.1 MPa, and the nitrogen filling time is 10 seconds.

[0040] Example 3: A long-lasting antibacterial agent for household paper, comprising the following raw materials in parts by weight: 40 kg of alkali lignin, 30 kg of zinc sulfate heptahydrate, 32 kg of calcium montmorillonite, 4 kg of citric acid, and 160 kg of deionized water; The antibacterial agent is a microsphere powder with a particle size of 10-50 μm, which forms a zinc-lignin dynamic coordination bond structure inside and is loaded with a calcium-based montmorillonite layered structure on the outside.

[0041] The alkali lignin is an industrial-grade product extracted from papermaking black liquor, with a purity ≥85%, and is processed by pulverizing and passing through an 80-mesh sieve; the zinc sulfate heptahydrate is agricultural-grade, with a purity ≥98%.

[0042] The fineness of the calcium-based montmorillonite is 200 mesh, and the moisture content is ≤5%; the mass ratio of alkali lignin to zinc sulfate heptahydrate is 1:1, and the amount of calcium-based montmorillonite added is 30% of the total raw material mass.

[0043] The preparation method of the long-lasting antibacterial agent for household paper includes the following steps: S1. Raw material pretreatment: alkali lignin is pulverized and passed through an 80-mesh sieve; calcium-based montmorillonite is dried at high temperature and then cooled to room temperature for later use. S2. Preparation of complexation reaction solution: Deionized water is injected into the stirring tank, the speed is controlled at 200 rpm and the temperature is 50-55℃. After zinc sulfate heptahydrate is added and dissolved, alkali lignin powder is added and stirred for 2 hours. Then citric acid is added and stirred for another 30 minutes. S3, Composite Reaction: Add pretreated calcium-based montmorillonite, maintain temperature and speed while stirring for 1 hour to obtain a mixed liquid; S4. Spray drying: The mixed liquid is fed into a spray dryer, and the inlet air temperature is controlled at 185℃, the outlet air temperature at 85℃, and the atomizer speed at 16000rpm to dry the composite powder. S5. Post-processing: The composite powder is classified by passing it through a three-layer vibrating sieve of 40-200 mesh, and the powder with a particle size of 10-50μm is collected. The powder is then vacuum-packed with nitrogen to obtain a long-lasting antibacterial agent for household paper.

[0044] In S1, the drying temperature of calcium-based montmorillonite is 105℃ and the drying time is 2h.

[0045] In S4, the feeding rate is 800 kg / h.

[0046] In step S5, the vacuum degree of the vacuum packaging is -0.1 MPa, and the nitrogen filling time is 10 seconds.

[0047] The following comparison model was also set: Comparative Example 1: Based on Example 2, the difference is that all solid raw materials are directly dry-mixed and ground to pass through a 200-mesh sieve to obtain a physically mixed powder. No aqueous complexation reaction or spray drying is performed, and no dynamic coordination bonds are formed. The rest is the same as Example 2.

[0048] Comparative Example 2: Based on Example 2, the difference is that: no calcium-based montmorillonite is added, only step S2 of the present invention is performed, and after obtaining the zinc-lignin complex solution, it is directly spray-dried to obtain powder. The rest is the same as Example 2.

[0049] Comparative Example 3: Based on Example 2, the difference is that zinc ions are replaced with copper ions, otherwise it is the same as Example 2.

[0050] Comparative Example 4: Commercially available dodecyl dimethyl benzyl ammonium chloride was used.

[0051] Performance Testing: The antibacterial agent was added to the pulp or coated onto the surface during toilet paper production, with the amount added being 0.5% of the oven-dry pulp mass of the tissue paper. The antibacterial properties of the toilet paper were tested according to GB / T 42702-2023 using a carrier antibacterial test. The toilet paper was then stored at 37°C and 45-75% humidity for 90 days, followed by another carrier antibacterial test. Safety and toxicological testing were conducted according to GB / T 16886.10. The results are shown below: Table 1. Test results of various properties of antibacterial toilet paper

[0052] Data Analysis: Examples 1-3, based on the design of zinc-lignin dynamic coordination bonds and montmorillonite layered structure, exhibit high stability and excellent performance. Initial antibacterial efficiency: Examples 1-3 showed initial antibacterial rates of over 98% against Escherichia coli and Staphylococcus aureus (up to 98.90%), indicating that the antibacterial system of the present invention benefits from the synergistic effect of zinc ions and lignin: zinc ions interfere with bacterial enzyme systems, lignin destroys cell membranes, and montmorillonite physically adsorbs bacteria. The three form a broad-spectrum antibacterial network of chemical and physical action, which can quickly inhibit common pathogens and meet the immediate antibacterial needs of household paper.

[0053] Long-lasting antibacterial retention rate: After 90 days of accelerated aging, the antibacterial rate of the examples remained above 97%, with an average antibacterial retention rate of nearly 99.5%. This confirms the long-lasting effect of dynamic coordination bonds, namely, the coordination bonds are stable during dry storage, preventing premature loss of antibacterial components; under aging conditions, the layered structure of montmorillonite provides physical protection for the coordination bonds, ensuring that the release rhythm of antibacterial components remains controllable.

[0054] Safety and suitability for use: The cytotoxicity RGR (relative proliferation rate) of the examples is ≥98, which meets the standard of "no cytotoxicity" in GB / T16886.10, indicating that the antibacterial agent of the present invention is non-irritating to the skin and suitable for infants and young children and people with sensitive skin; the average whiteness is 85.2, which is basically consistent with the whiteness of ordinary toilet paper (85-88) and will not affect the appearance of the product.

[0055] Process tolerance: In Examples 1-3, the ratio of alkali lignin and zinc sulfate heptahydrate was adjusted (30-40:40-30) and the spray drying feed rate was adjusted (800-1000 kg / h), but the performance did not fluctuate significantly, indicating that the formulation and preparation process of the present invention have a wide parameter range and a high tolerance for industrial production.

[0056] By comparing it with the comparative example, the necessity of the core design of the embodiment can be clearly seen: Comparative Example 1: Due to the omission of aqueous phase complexation and spray drying, no dynamic coordination bonds were formed, and the raw materials were mixed only through physical grinding. The initial antibacterial rate dropped to 96.50% (E. coli), and after 90 days of aging, the antibacterial rate plummeted to 65.20%, with a retention rate of only 65.13%. This result proves that dynamic coordination is the core of long-lasting antibacterial effects. Physically mixed antibacterial components are prone to precipitation and loss during storage and aging, failing to maintain a stable antibacterial effect.

[0057] Comparative Example 2: After removing montmorillonite, the initial antibacterial rate (97.40%) was close to that of the Example, but after 90 days of aging, the antibacterial rate dropped to 95.80%, with a retention rate of 98.36%, slightly lower than that of the Example. This is because the layered structure of montmorillonite not only adsorbs bacteria but also provides a protective layer for the zinc-lignin complex. Without montmorillonite, the complex is more susceptible to humidity and temperature in the aging environment, leading to a slight loss of antibacterial components. At the same time, the "friction peeling-surface regeneration" mechanism is lost in actual use, and the antibacterial performance will further decline after long-term use.

[0058] Comparative Example 3: The initial antibacterial rate of copper ions (99.80%) was slightly higher than that of zinc ions, but after 90 days of aging, the antibacterial rate plummeted to 90.10% (Escherichia coli) and 75.30% (Staphylococcus aureus), with a retention rate of only 72.49%. Furthermore, the cytotoxicity RGR dropped to 90, approaching the "slight toxicity" threshold. This is because copper ions are easily oxidized to form insoluble copper salts, which cannot be stably released through coordination bonds. Additionally, the cytotoxicity of copper ions is inherently higher than that of zinc ions, failing to meet the safety requirements for household paper.

[0059] Comparative Example 4: The initial antibacterial rate (96.90% / 99.90%) was close to that of the Example, but after 90 days of aging, the antibacterial rate dropped to 75.10% (E. coli), with a retention rate of 94.02%. This is an inherent defect of organic antibacterial agents. Quaternary ammonium salts are prone to migration and volatilization, and the effective ingredients are severely lost after long-term storage. Although its cytotoxicity RGR is 100, organic components pose a risk of skin irritation and do not conform to the green circular raw material design logic.

[0060] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A long-lasting antibacterial agent for household paper products, characterized in that, The antibacterial agent is a lignin-zinc-montmorillonite composite antibacterial agent, comprising the following raw materials in parts by weight: 30-40 parts alkali lignin, 30-40 parts zinc sulfate heptahydrate, 18-32 parts calcium-based montmorillonite, 4-8 parts citric acid, and 120-160 parts deionized water. The antibacterial agent is a microsphere powder with a particle size of 10-50 μm, which forms a zinc-lignin dynamic coordination bond structure inside and is loaded with a calcium-based montmorillonite layered structure on the outside.

2. The long-lasting antibacterial agent for household paper products according to claim 1, characterized in that, The alkali lignin is an industrial-grade product extracted from papermaking black liquor, with a purity ≥85%, and is processed by crushing and passing through an 80-mesh sieve; the zinc sulfate heptahydrate is agricultural-grade, with a purity ≥98%.

3. The long-lasting antibacterial agent for household paper products according to claim 1, characterized in that, The fineness of the calcium-based montmorillonite is 200 mesh, and the moisture content is ≤5%; the mass ratio of alkali lignin to zinc sulfate heptahydrate is 1:1, and the amount of calcium-based montmorillonite added is 30% of the total raw material mass.

4. A method for preparing a long-lasting antibacterial agent for household paper as described in any one of claims 1-3, characterized in that, Includes the following steps: S1. Raw material pretreatment: alkali lignin is pulverized and passed through an 80-mesh sieve; calcium-based montmorillonite is dried at high temperature and then cooled to room temperature for later use. S2. Preparation of complexation reaction solution: Inject deionized water into a stirring tank, control the rotation speed at 150-200 rpm and the temperature at 25-55℃, add zinc sulfate heptahydrate to dissolve, then add alkali lignin powder and stir for 1.5-2.5 h, then add citric acid to adjust the pH to 5.0-5.5, and continue stirring for 20-40 min. S3, Composite reaction: Add pretreated calcium-based montmorillonite, maintain temperature and speed while stirring for 0.8-1.2 hours to obtain a mixed liquid; S4. Spray drying: The mixed liquid is fed into a spray dryer, and the inlet air temperature is controlled at 180-190℃, the outlet air temperature at 80-90℃, and the atomizer speed at 15000-18000rpm to obtain composite powder. S5. Post-processing: The composite powder is classified by passing it through a three-layer vibrating sieve of 40-200 mesh, and the powder with a particle size of 10-50μm is collected. The powder is then vacuum-packed with nitrogen to obtain a long-lasting antibacterial agent for household paper.

5. The method for preparing the long-lasting antibacterial agent for household paper according to claim 4, characterized in that, In S1, the drying temperature of calcium-based montmorillonite is 105℃ and the drying time is 2h.

6. The method for preparing the long-lasting antibacterial agent for household paper according to claim 4, characterized in that, In S4, the feeding rate is 800-1000 kg / h.

7. The method for preparing the long-lasting antibacterial agent for household paper according to claim 4, characterized in that, In step S5, the vacuum degree of the vacuum packaging is -0.09 to -0.1 MPa, and the nitrogen filling time is 10-15 seconds.

8. The application of a long-lasting antibacterial agent for household paper as described in any one of claims 1-3 in household paper, characterized in that, The antibacterial agent is applied to the production of tissue paper by means of internal addition or surface coating, and the amount of antibacterial agent added is 0.05-0.5% of the oven-dry pulp mass of tissue paper; the tissue paper includes toilet paper, facial tissue, and kitchen paper.

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