Zinc ricinoleate composite antibacterial absorbent paper as well as preparation method and application thereof

Abstract

The invention relates to zinc ricinoleate composite antibacterial absorbent paper as well as a preparation method and application thereof. The method comprises the following steps: preparing a composite antibacterial solution from raw materials containing zinc diricinoleate, modified nano silicon dioxide and a dispersing agent; preparing composite antibacterial slurry from raw materials containing plant fibers, a composite antibacterial liquid and a humectant; the method comprises the following steps: spreading super absorbent resin on wet bottom layer paper to form a super absorbent resin layer, then laying a composite bacteriostatic paper pulp layer formed by composite bacteriostatic slurry on the super absorbent resin layer, and finally laying wet surface layer paper on the composite bacteriostatic paper pulp layer and carrying out wet pressing to obtain a wet paper blank; the wet paper blank is subjected to hot air drying at the temperature of 100-110 DEG C and treatment at the temperature of 80-90 DEG C for 20-30 min and then cooled, and the absorbent paper is prepared. Through construction of a composite antibacterial system, the problems that zinc diricinoleate is non-uniform in dispersion and easy to migrate are solved, and meanwhile, the synergistic high efficiency of water absorption, bacteriostasis and deodorization is effectively guaranteed.

Description

Technical Field

[0001] This invention belongs to the field of hygiene product materials technology, and particularly relates to a zinc ricinoleate composite antibacterial absorbent paper, its preparation method and application. Background Technology

[0002] Absorbent paper is a core component of personal care and hygiene products, and its absorbency and antibacterial / deodorizing properties directly affect the user experience. In existing technologies, some absorbent papers add antibacterial agents to enhance their antibacterial effect. Common antibacterial agents include quaternary ammonium salts, phenols, and metal ions, but these have several drawbacks: quaternary ammonium salt antibacterial agents are easily affected by environmental pH, resulting in poor antibacterial persistence; phenolic antibacterial agents have limited biocompatibility, and long-term skin contact may cause irritation; metal ion antibacterial agents are prone to migration and loss, affecting their long-term antibacterial effect.

[0003] Zinc ricinoleate, as an environmentally friendly antibacterial and deodorizing ingredient, has been used in fields such as hydrocolloid dressings and deodorants (e.g., CN106310353A discloses the use of zinc ricinoleate in hydrocolloid adhesives to absorb odors from wounds). However, when applied to absorbent paper, there are two key problems: First, zinc ricinoleate is unevenly dispersed in the absorbent paper fiber matrix and is prone to agglomeration, leading to a local imbalance in the antibacterial effect. Second, during the process of absorbent paper absorbing water and swelling, zinc ricinoleate is easily lost with the water migration, which cannot guarantee long-term antibacterial effect. Moreover, the existing technology has not been designed to be compatible with the structure of absorbent paper and zinc ricinoleate, making it difficult to take into account the three core properties of water absorption, antibacterial, and deodorization.

[0004] Therefore, there is an urgent need to provide an antibacterial absorbent paper that can achieve stable immobilization of zinc ricinoleate and take into account multiple properties, as well as its preparation method and application, to fill the gap in existing technology. Summary of the Invention

[0005] To address one or more technical problems existing in the prior art, this invention provides a zinc ricinoleate composite antibacterial absorbent paper, its preparation method, and its application. This invention solves the problems of uneven dispersion and easy migration of zinc ricinoleate through optimized structural design of the absorbent paper and the construction of a composite antibacterial system (composite antibacterial pulp layer), while effectively ensuring the synergistic efficiency of absorbency, antibacterial properties, and deodorization.

[0006] The present invention provides a method for preparing zinc ricinoleate composite antibacterial absorbent paper in a first aspect, the method comprising the following steps: (1) Disperse zinc ricinoleate and modified nano-silica with water using ultrasonication, then add a dispersant and stir evenly to obtain a composite antibacterial solution; (2) Use water to prepare plant fiber pulp, then add compound antibacterial liquid and humectant to the plant fiber pulp and stir evenly to obtain compound antibacterial pulp; (3) A super absorbent resin is spread on the wet bottom paper to form a super absorbent resin layer, and then a composite antibacterial pulp layer is laid on the super absorbent resin layer. Finally, a wet top paper is laid on the composite antibacterial pulp layer and wet-pressed to obtain a wet paper blank; the composite antibacterial pulp layer is formed by composite antibacterial pulp. (4) The wet paper blank is dried with hot air at 100~110℃ and treated at 80~90℃ for 20~30 minutes, and then cooled to obtain zinc ricinoleate composite antibacterial absorbent paper.

[0007] Preferably, the modified nano-silica is silane coupling agent modified nano-silica; more preferably, the silane coupling agent is silane coupling agent KH-550; more preferably, the particle size of the modified nano-silica is 50~100nm.

[0008] Preferably, the raw materials for preparing the composite antibacterial slurry contain the following components in parts by mass: 50-60 parts of plant fiber, 0.2-0.8 parts of zinc ricinoleate, 0.1-0.4 parts of modified nano silica, 0.1-0.3 parts of dispersant and 0.5-1.0 parts of humectant.

[0009] Preferably, in the zinc ricinoleate composite antibacterial absorbent paper, the mass ratio of the composite antibacterial slurry to the superabsorbent resin is (50~75):(25~50), more preferably (50~75):(25~30); the dispersant is polyoxyethylene sorbitan monolaurate; and / or the humectant is glycerin.

[0010] Preferably, the wet bottom layer paper is formed from a bottom layer pulp. More preferably, the bottom layer pulp is prepared by: mixing plant fibers with water to prepare a plant fiber pulp with a concentration of 12-16 wt%, and then adding polyethylene glycol monostearate to the plant fiber pulp and stirring evenly. The wet top layer paper is formed from a top layer pulp. More preferably, the top layer pulp is prepared by: mixing plant fibers with water to prepare a plant fiber pulp with a concentration of 8-10 wt%, and then adding polyethylene glycol monostearate to the plant fiber pulp and stirring evenly.

[0011] Preferably, in the preparation of the bottom slurry and / or the top slurry, the mass ratio of polyethylene glycol monostearate to the plant fiber contained in the plant fiber slurry is (0.3~0.5):(20~30).

[0012] Preferably, the superabsorbent resin is a polyacrylate superabsorbent resin and / or an acrylate-acrylamide copolymer; more preferably, the polyacrylate superabsorbent resin is sodium polyacrylate superabsorbent resin.

[0013] Preferably, in step (1), the ultrasonic dispersion power is 300~400W and the ultrasonic dispersion time is 15~20min; in step (1), the stirring speed is 800~1000r / min and the stirring time is 30~40min; in step (2), the concentration of the composite antibacterial slurry is adjusted to 10~15wt%; in step (2), the pH of the composite antibacterial slurry is adjusted to 6.5~7.5; and / or in step (2), the stirring speed is 600~800r / min and the stirring time is 5~15min.

[0014] In a second aspect, the present invention provides a zinc ricinoleate composite antibacterial absorbent paper prepared by the preparation method described in the first aspect of the present invention.

[0015] In a third aspect, the present invention provides the application of zinc ricinoleate composite antibacterial absorbent paper prepared by the preparation method described in the first aspect of the present invention in sanitary products; preferably, the sanitary products are one or more of sanitary napkins, diapers, and nursing pads; more preferably, the zinc ricinoleate composite antibacterial absorbent paper serves as the absorbent and antibacterial layer of the sanitary products.

[0016] Compared with the prior art, the present invention has at least the following beneficial effects: (1) The zinc ricinoleate composite antibacterial absorbent paper prepared by the present invention solves one or more problems of existing absorbent paper, such as poor antibacterial persistence, conflict between odor adsorption and water absorption performance, uneven dispersion of zinc ricinoleate, and easy migration and loss of components. It is suitable for sanitary products such as sanitary napkins and diapers. The absorbent paper in the present invention adopts a layered composite structure. The middle layer is based on plant fiber and is loaded with a composite antibacterial liquid containing zinc ricinoleate and modified nano silica. It is also equipped with super absorbent resin to improve water-locking ability. The surface and bottom layers are preferably treated with hydrophilic modification (polyethylene glycol monostearate hydrophilic modification treatment) to ensure liquid penetration efficiency. Through the structural optimization design of the absorbent paper and the construction of the composite antibacterial system (composite antibacterial pulp layer), the problems of uneven dispersion and easy migration of zinc ricinoleate are solved. At the same time, the synergistic efficiency of water absorption, antibacterial and deodorization is effectively guaranteed.

[0017] (2) The absorbent paper prepared by the present invention has a long-lasting and stable antibacterial effect. In the composite antibacterial system, the modified nano silica forms a stable immobilization on zinc ricinoleate. After 50 water washing-drying cycles, the antibacterial rate is still above 95%, which solves the problem of easy migration and loss of existing antibacterial agents. The preparation process of the present invention adopts in-situ dispersion combined with drying process to achieve stable immobilization of antibacterial components, with no obvious component migration, and excellent multi-performance synergy: water absorption ratio ≥35g / g, odor adsorption rate ≥85%, antibacterial rate against Escherichia coli and Staphylococcus aureus both reach above 99%, and at the same time, the water-locking and anti-backflow effect is outstanding, with no surface liquid accumulation and bottom backflow phenomenon, taking into account both user experience and functional needs.

[0018] (3) The raw materials used in the absorbent paper prepared by the present invention all comply with GB 15979-2002 "Hygienic Standard for Disposable Sanitary Products", have excellent biocompatibility, and are non-irritating in skin irritation tests. They are suitable for sanitary products that come into long-term contact with the skin, so that the absorbent paper can be mainly used in the core absorbent and antibacterial layer of personal care sanitary products such as sanitary napkins, diapers, and nursing pads.

[0019] (4) The preparation process of this invention is simple and adaptable to existing production lines. It can be produced using existing papermaking equipment without the need for additional special equipment. The production cost is controllable and it is easy to scale up production. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with the embodiments thereof. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0021] The present invention provides a method for preparing zinc ricinoleate composite antibacterial absorbent paper (abbreviated as absorbent paper) in a first aspect, the method comprising the following steps: (1) Zinc ricinoleate and modified nano silica are ultrasonically dispersed with water, and then a dispersant is added and stirred evenly to obtain a composite antibacterial solution; In this invention, the zinc ricinoleate can be, for example, powdered zinc ricinoleate with a particle size of 1-5 μm; In this invention, the combination of ultrasonic dispersion and stirring (e.g., high-speed stirring) can ensure that zinc ricinoleate and modified nano silica are uniformly mixed to form a stable suspension.

[0022] (2) Plant fiber is prepared into plant fiber pulp with water, and then composite antibacterial liquid and humectant are added to the plant fiber pulp and stirred evenly to obtain composite antibacterial pulp. The present invention does not specifically limit the dispersant and humectant. Those skilled in the art can choose conventionally. The purpose of the dispersant is to effectively ensure the uniform dispersion of the components and avoid the aggregation of antibacterial components. The main purpose of the humectant is to improve the moisture retention of the composite antibacterial pulp layer and avoid the drying and embrittlement of the absorbent paper. This can also indirectly support the stability of antibacterial dispersion and effectively avoid the local concentration change caused by the drying and embrittlement of the absorbent paper. This can also avoid the aggregation of antibacterial components and work together with the dispersant to ensure the uniform dispersion of the components.

[0023] (3) A superabsorbent polymer (SAP) layer is formed by spreading SAP on the wet bottom paper, and then a composite antibacterial pulp layer is laid on the SAP layer. Finally, a wet top paper is laid on the composite antibacterial pulp layer and wet-pressed to obtain a wet paper blank. The composite antibacterial pulp layer is formed from composite antibacterial pulp, and the relative moisture content of the composite antibacterial pulp layer is, for example, 50-60%. In this invention, the wet bottom paper is formed from bottom pulp, and the wet top paper is formed from top pulp. The wet bottom paper and the wet top paper are formed from top pulp. / Or the relative moisture content of the wet surface layer is, for example, 50-60%; the wet pressing can be, for example, pressing at room temperature (15-35°C) with a pressure of 0.5-2.0 MPa for 10-60 seconds; the present invention does not specifically limit the forming conditions of the composite antibacterial pulp layer, the wet bottom paper, and the wet surface paper, and those skilled in the art can choose conventionally; in the present invention, for example, the thickness of each layer can be precisely controlled by a paper machine and wet pressing can be used to ensure tight bonding between layers and no delamination.

[0024] (4) The wet paper blank is dried with hot air at 100~110℃ and treated at 80~90℃ for 20~30min, and then cooled (naturally cooled to room temperature) to obtain zinc ricinoleate composite antibacterial absorbent paper; In this invention, preferably, the wet paper blank is first dried with hot air at 100~110℃ until the relative moisture content of the wet paper blank is 15~20%, and then treated at 80~90℃ for 20~30min; In this invention, the room temperature is, for example, room temperature of 15~35℃; In this invention, the zinc ricinoleate composite antibacterial absorbent paper includes, from bottom to top, a bottom layer, a composite antibacterial intermediate layer and a top layer; The composite antibacterial intermediate layer is composed of a super absorbent resin layer and a composite antibacterial pulp layer.

[0025] In existing technologies, zinc ricinoleate is mainly used in hydrocolloid dressings and deodorants. However, if zinc ricinoleate is directly applied as an antibacterial ingredient to absorbent paper, problems arise such as uneven dispersion and easy migration of zinc ricinoleate, leading to poor long-term antibacterial stability and low odor adsorption rate. This invention solves the problems of uneven dispersion and easy migration of zinc ricinoleate by optimizing the structure of absorbent paper and constructing a composite antibacterial system (composite antibacterial pulp layer). This achieves stable immobilization of the antibacterial ingredient, effectively ensuring the synergistic and efficient multi-performance of absorbency, antibacterial activity, and deodorization.

[0026] This invention utilizes a design that involves ultrasonically dispersing zinc ricinoleate and modified nano-silica with the addition of a dispersant to prepare a composite antibacterial liquid. This liquid is then mixed with plant fiber pulp to form a composite antibacterial slurry. After molding to obtain a composite antibacterial pulp layer, this slurry is laid on a superabsorbent resin layer and wet-pressed to construct a composite antibacterial intermediate layer (comprising the composite antibacterial pulp layer and the superabsorbent resin layer). Compared to directly spraying the composite antibacterial liquid onto the superabsorbent resin layer to construct the composite antibacterial layer, this design effectively solves the problems of uneven dispersion and easy migration of zinc ricinoleate, and improves the stability of the antibacterial components. This is likely because it allows the plant fiber to serve as a substrate for loading the composite antibacterial liquid, and the modified nano-silica surface groups can interact with zinc ricinoleate through hydrogen bonds and / or coordination bonds. Constructing a network structure facilitates the stable immobilization of zinc ricinoleate on the plant fiber substrate. Furthermore, the wet pressing process allows the plant fiber portion of the composite antibacterial pulp layer to encapsulate the superabsorbent resin particles, forming a tight interlayer bond. This physical encapsulation not only further fixes the superabsorbent resin, preventing its displacement or aggregation during water absorption and swelling, but also enables the composite antibacterial pulp layer and the superabsorbent resin layer to work synergistically. This allows the surrounding composite antibacterial components to quickly contact and inhibit bacteria in the liquid when the superabsorbent resin absorbs liquid. At the same time, the plant fiber substrate provides a slow-release carrier for the antibacterial components, avoiding the local aggregation or rapid migration and loss of antibacterial agents that may occur with direct spraying. This more effectively ensures the synergistic high efficiency of water absorption, antibacterial, and deodorization properties. This invention utilizes a composite antibacterial solution prepared by pre-ultrasonic dispersion of zinc ricinoleate and modified nano-silica with the addition of a dispersant. Compared to directly combining zinc ricinoleate, nano-silica, and a silane coupling agent, or simply combining zinc ricinoleate and nano-silica, this method leverages the active groups on the surface of modified nano-silica to form a more stable and uniform interaction with zinc ricinoleate, creating a network-like composite antibacterial system. This overcomes the problems of insufficient surface activity in unmodified nano-silica leading to poor loading and easy migration of zinc ricinoleate. It significantly improves the dispersion uniformity and fixation stability of the antibacterial component zinc ricinoleate in the fiber substrate, ensuring a long-lasting and highly effective antibacterial effect.

[0027] Another key improvement of this invention lies in its two-step process of "high-temperature rapid drying and low-temperature heat treatment." First, most of the free moisture is rapidly removed by high-temperature hot air drying at 100-110℃, resulting in a moisture content of 15-20% for the wet paper blank, laying the foundation for subsequent processing. Then, a heat treatment is carried out at a relatively low temperature of 80-90℃ for 20-30 minutes. This stage is not simply drying, but rather, while the paper blank retains an appropriate amount of moisture, a gentle heat treatment is used to promote a full and stable combination between the modified nano-silica and zinc ricinoleate network composite antibacterial system and the functional groups on the surface of the plant fibers. This further enhances the stability of the antibacterial component and facilitates the firm fixation of the antibacterial component on the fiber network. This invention reveals that if excessive moisture is removed during the initial high-temperature drying process, the plant fibers and antibacterial components will lose their necessary molecular activity due to excessive dryness. Low-temperature heat treatment is insufficient to effectively promote this interfacial bonding and stabilization process. Furthermore, while direct drying at 100-110°C can quickly remove moisture, continuous treatment at this temperature will preferentially accelerate the rapid evaporation of moisture, potentially leading to rapid water loss and shrinkage of the fiber surface, and a decrease in molecular migration ability. This is also detrimental to promoting sufficient and stable contact and bonding between the modified nano-silica and zinc ricinoleate network composite antibacterial system and the functional groups on the plant fiber surface. Simultaneously, prolonged high-temperature treatment may cause excessive thermal stress changes in the plant fibers, affecting their flexibility and strength.

[0028] According to some preferred embodiments, the modified nano-silica is silane coupling agent modified nano-silica; preferably, the silane coupling agent is silane coupling agent KH-550; in this invention, the composite antibacterial liquid simultaneously contains zinc ricinoleate and modified nano-silica, wherein the modified nano-silica is preferably silane coupling agent (e.g., KH-550) modified nano-silica, so that after modification with KH-550, the surface groups of the nano-silica form hydrogen bonds and / or coordination bonds with zinc ricinoleate, constructing a network structure, stably immobilizing zinc ricinoleate on the plant fiber substrate, preventing migration and loss, and achieving efficient immobilization of zinc ricinoleate; this invention does not specifically limit the source of the silane coupling agent modified nano-silica, and can use directly purchased products. The product is prepared uniformly by existing methods; for example, the preparation method of the silane coupling agent modified nano-silica includes: adding nano-silica to water and dispersing it uniformly to obtain a nano-silica suspension; adding an acidified silane coupling agent to the nano-silica suspension; and heating and refluxing to obtain the silane coupling agent modified nano-silica. The conditions for the heating and refluxing reaction are 70~85℃ for 30~180 min. The mass ratio of the silane coupling agent to the nano-silica is, for example, 1:(4~7). The preparation of the acidified silane coupling agent can be, for example, mixing the silane coupling agent with dilute hydrochloric acid with a concentration of 1~5wt% at a mass ratio of 1:(5~10) and stirring for 5~10 min to obtain the acidified silane coupling agent.

[0029] According to some preferred embodiments, the particle size of the modified nano-silica is 50~100nm.

[0030] According to some preferred embodiments, the raw materials for preparing the composite antibacterial slurry contain the following components in parts by mass: 50-60 parts plant fiber, 0.2-0.8 parts zinc ricinoleate, 0.1-0.4 parts modified nano silica, 0.1-0.3 parts dispersant and 0.5-1.0 parts humectant.

[0031] In this invention, the preferred mass ratio of plant fiber, zinc ricinoleate, and modified nano-silica is (50~60):(0.2~0.8):(0.1~0.4). The amount of zinc ricinoleate added ensures both antibacterial and deodorizing effects while avoiding excessive addition that could affect the softness of the absorbent paper. The amount of modified nano-silica added allows the surface groups of the modified nano-silica to effectively form a network structure with zinc ricinoleate, stably immobilizing zinc ricinoleate on the plant fiber substrate and preventing migration and loss. An addition amount of 0.1-0.4 parts is sufficient to achieve efficient immobilization. In this invention, unless otherwise specified, "parts" refers to "parts by weight." In specific embodiments and comparative examples, the unit of parts by weight can be uniformly "g" or "kg" or other weight units.

[0032] According to some preferred embodiments, in the zinc ricinoleate composite antibacterial absorbent paper, the mass ratio of the composite antibacterial slurry to the superabsorbent resin is (50~75):(25~50), preferably (50~75):(25~35); the dispersant is polyoxyethylene sorbitan monolaurate (Tween-20); and / or the humectant is glycerin.

[0033] According to some preferred embodiments, the raw materials for preparing the composite antibacterial intermediate layer comprise the following components in parts by mass: The ingredients include 50-60 parts plant fiber, 0.2-0.8 parts zinc ricinoleate, 0.1-0.4 parts modified nano silica, 25-50 parts superabsorbent resin, 0.1-0.3 parts dispersant, and 0.5-1.0 parts humectant.

[0034] According to some preferred embodiments, the wet bottom layer paper is formed from a bottom layer pulp. Preferably, the bottom layer pulp is prepared by: mixing plant fibers with water to form a plant fiber pulp with a concentration of 12-16 wt%, then adding polyethylene glycol monostearate to the plant fiber pulp and stirring evenly. The wet top layer paper is formed from a top layer pulp. Preferably, the top layer pulp is prepared by: mixing plant fibers with water to form a plant fiber pulp with a concentration of 8-10 wt%, then adding polyethylene glycol monostearate to the plant fiber pulp and stirring evenly. The concentration of the plant fiber pulp refers to the percentage by mass of plant fibers contained in the plant fiber pulp. Another key improvement of the present invention is that: the present invention uses polyethylene glycol monostearate for hydrophilic modification, which not only effectively improves the hydrophilicity of the top and bottom layers of paper, but also effectively improves the dispersion uniformity and wettability of the plant fiber pulp in each layer, which helps to control the concentration of the plant fiber pulp in the top and bottom layers. The invention constructs a precise gradient pore size structure from the surface paper (pore size 80-120μm) to the bottom paper (pore size 20-50μm), making the surface layer of the absorbent paper a permeable surface layer. Through this hydrophilic modification treatment, the pore size is relatively large (80-120μm), ensuring rapid liquid penetration to the core layer (composite antibacterial intermediate layer) and preventing surface liquid accumulation. The bottom layer of the absorbent paper is a water-locking bottom layer with a smaller pore size (20-50μm), possessing both water-locking and anti-backflow functions, reducing water reflux. This invention prevents the migration of antibacterial components in the core layer (composite antibacterial intermediate layer). The invention found that this hydrophilic modification method promotes the formation of more uniform and stable pores between fibers, which can help construct precise gradient pore sizes. While other hydrophilic materials, such as common hydrophilic treatment materials, such as simple hydrophilic polymers (e.g., polyethylene glycol, polyvinyl alcohol), can improve the hydrophilicity of plant fibers, they usually have poor ability to help regulate the macroscopic pore size distribution and are difficult to optimize the interlayer bonding force simultaneously during the dehydration and molding process.

[0035] According to some preferred embodiments, in the preparation of the bottom slurry and / or the top slurry, the mass ratio of polyethylene glycol monostearate to the plant fiber contained in the plant fiber slurry is (0.3~0.5):(20~30). This ratio ensures that polyethylene glycol monostearate molecules can be fully adsorbed on the surface of the plant fiber, effectively regulating the dispersion and interfacial characteristics of the plant fiber. This, in turn, synergizes with the plant fiber concentration during subsequent molding, which is beneficial for guiding and stabilizing the formation of the required gradient pore structure (large pores on the surface and small pores on the bottom) and optimizing interlayer bonding. The present invention found that if the amount of polyethylene glycol monostearate is too low, the hydrophilic modification effect is insufficient, making it difficult to effectively control the fiber arrangement, resulting in a rough or uneven pore structure, weakened gradient characteristics, and decreased interlayer bonding. Conversely, if the amount of polyethylene glycol monostearate is too high, the excessive amount of polyethylene glycol monostearate interferes with the bonding between fibers, resulting in a loose paper structure and affecting the overall performance of the absorbent paper.

[0036] In this invention, the permeable surface layer, after undergoing hydrophilic modification treatment, has a larger pore size (80-120μm), which effectively ensures rapid liquid penetration to the core layer and prevents surface liquid accumulation. The core layer contains a composite antibacterial liquid of zinc ricinoleate and modified nano-silica loaded in plant fibers, combined with a superabsorbent resin, to simultaneously achieve antibacterial, water absorption, and water retention. The water-locking bottom layer has a smaller pore size (20-50μm), combining water retention and anti-backflow functions, effectively reducing water reflux and preventing the migration of antibacterial components from the core layer.

[0037] This invention does not impose specific limitations on the plant fibers involved; those skilled in the art can make conventional choices.

[0038] According to some preferred embodiments, the plant fiber is a mixture of softwood pulp and cotton linters in a mass ratio of 3:(1.5~2.5) (e.g., 3:1.5, 3:2 or 3:2.5), preferably 3:2; in this invention, it is preferable that the plant fiber in the plant fiber pulp is a mixture of softwood pulp and cotton linters in a mass ratio of 3:(1.5~2.5), which can balance the softness and absorbency of absorbent paper.

[0039] This invention does not specifically limit the superabsorbent resins involved; those skilled in the art can choose conventionally.

[0040] According to some preferred embodiments, the superabsorbent resin is a polyacrylate superabsorbent resin and / or an acrylate-acrylamide copolymer; preferably, the polyacrylate superabsorbent resin is sodium polyacrylate superabsorbent resin. This invention has found that sodium polyacrylate superabsorbent resin has a fast absorption rate and high gel strength, and can synergistically lock in water with plant fibers, preventing it from collapsing after water absorption. In this invention, the water absorption rate of the sodium polyacrylate superabsorbent resin is, for example, ≤50s, and the pressure absorption ratio at 0.7Psi is ≥10.0.

[0041] According to some preferred embodiments, in step (1), the ultrasonic dispersion power is 300~400W, and the ultrasonic dispersion time is 15~20min; in step (1), the stirring speed is 800~1000r / min, and the stirring time is 30~40min; in step (2), for example, deionized water is added to adjust the concentration of the composite antibacterial slurry to 10~15wt%; in this invention, the concentration of the composite antibacterial slurry refers to the concentration of zinc ricinoleate, modified nano silica, dispersant, and preservative contained in the composite antibacterial slurry. The sum of the mass percentages of the wetting agent; before preparing the plant fiber slurry in this invention, the plant fiber is first crushed to 200-300 mesh; in step (2), the pH of the composite antibacterial slurry is adjusted to 6.5-7.5; in this invention, for example, a pH adjuster is used to adjust the pH of the composite antibacterial slurry to 6.5-7.5. This invention does not make specific limitations on the pH adjuster used, and those skilled in the art can choose conventionally; and / or in step (2), the stirring speed is 600-800 r / min, and the stirring time is 5-15 min.

[0042] According to some specific implementation methods, step (1) is as follows: zinc ricinoleate and modified nano silica are added to deionized water, ultrasonically dispersed for 15-20 min, then a dispersant is added and stirred for 30-40 min to obtain a uniformly dispersed composite antibacterial solution; the ultrasonic dispersion power is 300-400W; the stirring speed is 800-1000r / min; in this step (1), the mass ratio of zinc ricinoleate, modified nano silica, dispersant and deionized water is (0.2-0.8):(0.1-0.4):(0.1-0.3):(50-70).

[0043] According to some specific implementation methods, step (2) is as follows: the plant fiber is crushed to 200-300 mesh, deionized water is added to prepare a plant fiber slurry, a composite antibacterial liquid and a humectant are added in sequence, and the mixture is stirred for 5-15 minutes. Then the concentration of the composite antibacterial slurry is adjusted to 10wt%-15wt%, and the pH is adjusted to 6.5-7.5. In this step (2), when preparing the plant fiber slurry, the mass ratio of the plant fiber to the water is (50~60):(200~250); the stirring speed is 600~800r / min.

[0044] According to some specific implementation methods, step (3) includes: preparation of surface slurry and bottom slurry: Plant fibers pulverized to 200-300 mesh are mixed with water to prepare a plant fiber slurry with a concentration of 8wt%-10wt%, then polyethylene glycol monostearate is added to the plant fiber slurry and stirred for 5-10 minutes to obtain the surface slurry; plant fibers pulverized to 200-300 mesh are mixed with water to prepare a plant fiber slurry with a concentration of 12-16wt%, then polyethylene glycol monostearate is added to the plant fiber slurry and stirred for 5-10 minutes to obtain the bottom slurry. In the preparation of the bottom slurry and the surface slurry, polyethylene glycol monostearate and the plant fiber pulverized to 200-300 mesh are mixed with water to prepare a plant fiber slurry with a concentration of 12-16wt%, then polyethylene glycol monostearate is added to the plant fiber slurry and stirred for 5-10 minutes to obtain the bottom slurry. The plant fiber pulp contains plant fibers in a mass ratio of (0.3~0.5):(20~30); then, a surface pulp is used to form a wet surface paper, and a bottom pulp is used to form a wet bottom paper; superabsorbent polymer is spread on the wet bottom paper to form a superabsorbent polymer layer, and then a composite antibacterial pulp layer is laid on the superabsorbent polymer layer; finally, the wet surface paper is laid on the composite antibacterial pulp layer and wet-pressed to obtain a wet paper blank; the composite antibacterial pulp layer is formed from composite antibacterial pulp, the relative moisture content of the composite antibacterial pulp layer is 50~60%, and the wet pressing is performed at room temperature (15~35℃) with a pressure of 0.5~2.0MPa for 10~60s.

[0045] According to some specific implementation methods, step (4) is as follows: the wet paper blank is dried with hot air at 100~110℃ until the relative moisture content of the wet paper blank is 15~20%, and then placed at 80~90℃ for 20~30 minutes. After cooling, it is cut to obtain zinc ricinoleate composite antibacterial absorbent paper. In this invention, the cooling is natural cooling to room temperature of 15~35℃.

[0046] In a second aspect, the present invention provides a zinc ricinoleate composite antibacterial absorbent paper prepared by the preparation method described in the first aspect of the present invention.

[0047] In a third aspect, the present invention provides the application of zinc ricinoleate composite antibacterial absorbent paper prepared by the preparation method described in the first aspect of the present invention in sanitary products; preferably, the sanitary products are one or more of sanitary napkins, diapers, and nursing pads; more preferably, the zinc ricinoleate composite antibacterial absorbent paper serves as the absorbent and antibacterial layer of the sanitary products.

[0048] The present invention will be further described below by way of examples, but the scope of protection of the present invention is not limited to these embodiments. The present invention may have many other embodiments, and those skilled in the art can make various corresponding changes and modifications based on the present invention without departing from its spirit and essence. However, all such corresponding changes and modifications should fall within the scope of protection of the appended claims. Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods. Unless otherwise stated, the raw materials and reagents used in the following embodiments and comparative examples are purchased products or prepared by known methods.

[0049] In the following embodiments and comparative examples, the plant fiber used is a mixture of softwood pulp and cotton linters in a mass ratio of 3:2; the superabsorbent resin is sodium polyacrylate superabsorbent resin.

[0050] Example 1 (1) Add 0.5g zinc ricinoleate and 0.2g silane coupling agent KH-550 modified nano silica to 50g deionized water, and ultrasonically disperse (ultrasonic dispersion power is 300W) for 15min. Then add 0.1g polyoxyethylene dehydrated sorbitan monolaurate (Tween-20) and stir at 800r / min for 30min to obtain composite antibacterial solution.

[0051] (2) Take 50g of plant fiber and crush it to 200 mesh. Add 200g of deionized water to prepare plant fiber slurry. Add the composite antibacterial liquid obtained in step (1) and 0.5g of glycerin in sequence. Stir at 600r / min for 8min. Then adjust the concentration of the composite antibacterial slurry to 10wt% and the pH to 6.5 to obtain the composite antibacterial slurry.

[0052] (3) Prepare a plant fiber slurry with a concentration of 8wt% by mixing 20g of plant fiber pulverized to 200 mesh with deionized water. Then add 0.3g of polyethylene glycol monostearate to the plant fiber slurry and stir at 600r / min for 10min to obtain a surface slurry. Prepare a plant fiber slurry with a concentration of 12wt% by mixing 20g of plant fiber pulverized to 200 mesh with deionized water. Then add 0.3g of polyethylene glycol monostearate to the plant fiber slurry and stir at 600r / min for 10min to obtain a bottom slurry. Then use the surface slurry. The wet surface paper is formed by molding the material, and the wet bottom paper is formed by molding the bottom pulp. The relative moisture content of the wet surface paper and the wet bottom paper is 55%. The composite antibacterial pulp obtained in step (2) is used to form a composite antibacterial pulp layer. The relative moisture content of the composite antibacterial pulp layer is 55%. 25g of superabsorbent resin is spread on the wet bottom paper to form a superabsorbent resin layer. Then the composite antibacterial pulp layer is laid on the superabsorbent resin layer. Finally, the wet surface paper is laid on the composite antibacterial pulp layer and wet-pressed to obtain a wet paper blank. The wet pressing is pressing at a pressure of 1.0MPa for 30s at room temperature.

[0053] (4) The wet paper blank is dried with hot air at 100°C until the relative moisture content of the wet paper blank is 15%, and then heat-treated at 80°C for 20 minutes. After cooling, it is cut to obtain zinc ricinoleate composite antibacterial absorbent paper.

[0054] The pore size of the surface layer of the zinc ricinoleate composite antibacterial absorbent paper prepared in this embodiment was measured to be 100~120μm, and the pore size of the bottom layer was measured to be 35~50μm.

[0055] Example 2 (1) Add 0.6g zinc ricinoleate and 0.3g silane coupling agent KH-550 modified nano silica to 60g deionized water, and ultrasonically disperse (power 350W) for 18min. Then add 0.15g polyoxyethylene dehydrated sorbitan monolaurate (Tween-20), and stir at 900r / min for 35min to obtain a uniform and stable composite antibacterial solution.

[0056] (2) Take 55g of plant fiber and crush it to 250 mesh. Add 220g of deionized water to prepare plant fiber slurry. Add the composite antibacterial liquid obtained in step (1) and 0.6g of glycerol in sequence. Stir at 700r / min for 5min. Then adjust the concentration of the composite antibacterial slurry to 12wt% and the pH to 7.0 to obtain the composite antibacterial slurry.

[0057] (3) Prepare a 9wt% plant fiber slurry by mixing 25g of plant fiber pulverized to 250 mesh with deionized water. Then add 0.4g of polyethylene glycol monostearate to the plant fiber slurry and stir at 700r / min for 10min to obtain a surface slurry. Prepare a 14wt% plant fiber slurry by mixing 25g of plant fiber pulverized to 250 mesh with deionized water. Then add 0.4g of polyethylene glycol monostearate to the plant fiber slurry and stir at 700r / min for 10min to obtain a bottom slurry. Then use the surface slurry... The wet surface paper is formed by molding the material, and the wet bottom paper is formed by molding the bottom pulp. The relative moisture content of the wet surface paper and the wet bottom paper is 55%. The composite antibacterial pulp obtained in step (2) is used to form a composite antibacterial pulp layer. The relative moisture content of the composite antibacterial pulp layer is 55%. 30g of superabsorbent resin is spread on the wet bottom paper to form a superabsorbent resin layer. Then the composite antibacterial pulp layer is laid on the superabsorbent resin layer. Finally, the wet surface paper is laid on the composite antibacterial pulp layer and wet-pressed to obtain a wet paper blank. The wet pressing is pressing at a pressure of 1.0MPa for 30s at room temperature.

[0058] (4) The wet paper blank is dried with hot air at 105℃ until the relative moisture content of the wet paper blank is 18%, and then heat-treated at 85℃ for 25 minutes. After cooling, it is cut to obtain zinc ricinoleate composite antibacterial absorbent paper.

[0059] The pore size of the surface layer of the zinc ricinoleate composite antibacterial absorbent paper prepared in this embodiment was measured to be 90~105μm, and the pore size of the bottom layer was measured to be 30~40μm.

[0060] Example 3 (1) Add 0.8g zinc ricinoleate and 0.4g silane coupling agent KH-550 modified nano silica to 70g deionized water, and ultrasonically disperse (ultrasonic dispersion power is 400W) for 20min. Then add 0.3g polyoxyethylene dehydrated sorbitan monolaurate (Tween-20) and stir at 1000r / min for 40min to obtain composite antibacterial solution.

[0061] (2) Take 60g of plant fiber and crush it to 300 mesh. Add 250g of deionized water to prepare plant fiber slurry. Add the composite antibacterial liquid obtained in step (1) and 1g of glycerin in sequence. Stir at 800r / min for 15min. Then adjust the concentration of the composite antibacterial slurry to 15wt% and the pH to 7.5 to obtain the composite antibacterial slurry.

[0062] (3) Prepare a 10wt% plant fiber slurry by mixing 30g of plant fiber pulverized to 300 mesh with deionized water. Then add 0.5g of polyethylene glycol monostearate to the plant fiber slurry and stir at 800r / min for 10min to obtain a surface slurry. Prepare a 16wt% plant fiber slurry by mixing 30g of plant fiber pulverized to 300 mesh with deionized water. Then add 0.5g of polyethylene glycol monostearate to the plant fiber slurry and stir at 800r / min for 10min to obtain a bottom slurry. Then apply the surface slurry... Wet surface paper is obtained by pulp molding, and wet bottom paper is obtained by bottom pulp molding. The relative moisture content of the wet surface paper and the wet bottom paper is 55%. Composite antibacterial pulp layer is obtained by molding the composite antibacterial pulp obtained in step (2). The relative moisture content of the composite antibacterial pulp layer is 55%. 35g of superabsorbent resin is spread on the wet bottom paper to form a superabsorbent resin layer. Then the composite antibacterial pulp layer is laid on the superabsorbent resin layer. Finally, the wet surface paper is laid on the composite antibacterial pulp layer and wet-pressed to obtain a wet paper blank. The wet pressing is pressing at a pressure of 1.0MPa for 30s at room temperature.

[0063] (4) The wet paper blank is dried with hot air at 110°C until the relative moisture content of the wet paper blank is 20%, and then heat-treated at 90°C for 30 minutes. After cooling, it is cut to obtain zinc ricinoleate composite antibacterial absorbent paper.

[0064] The pore size of the surface layer of the zinc ricinoleate composite antibacterial absorbent paper prepared in this embodiment is measured to be 80~95μm, and the pore size of the bottom layer is measured to be 20~35μm.

[0065] Example 4 Example 4 is basically the same as Example 3, except that: (3) Prepare a 10wt% plant fiber slurry by mixing 30g of plant fiber pulverized to 300 mesh with deionized water. Then add 0.05g of polyethylene glycol monostearate to the plant fiber slurry and stir for 10min at 800r / min to obtain the surface slurry. Prepare a 16wt% plant fiber slurry by mixing 30g of plant fiber pulverized to 300 mesh with deionized water. Then add 0.05g of polyethylene glycol monostearate to the plant fiber slurry and stir for 10min at 800r / min to obtain the bottom slurry. Then use the surface slurry to prepare the bottom slurry. A wet top layer paper is obtained by forming a layer of pulp, and a wet bottom layer paper is obtained by forming a bottom layer of pulp. The relative moisture content of the wet top layer paper and the wet bottom layer paper is 55%. A composite antibacterial pulp layer is obtained by forming a composite antibacterial pulp layer using the composite antibacterial pulp obtained in step (2). The relative moisture content of the composite antibacterial pulp layer is 55%. 35g of superabsorbent resin is spread on the wet bottom layer paper to form a superabsorbent resin layer. Then, the composite antibacterial pulp layer is laid on the superabsorbent resin layer. Finally, the wet top layer paper is laid on the composite antibacterial pulp layer and wet-pressed to obtain a wet paper blank. The wet pressing is pressing at a pressure of 1.0MPa for 30s at room temperature.

[0066] Example 5 Example 5 is basically the same as Example 3, except that: (3) Prepare a 10wt% plant fiber slurry by mixing 30g of plant fiber pulverized to 300 mesh with deionized water. Then add 1.5g of polyethylene glycol monostearate to the plant fiber slurry and stir at 800r / min for 10min to obtain a surface slurry. Prepare a 16wt% plant fiber slurry by mixing 30g of plant fiber pulverized to 300 mesh with deionized water. Then add 1.5g of polyethylene glycol monostearate to the plant fiber slurry and stir at 800r / min for 10min to obtain a bottom slurry. Then apply the surface slurry... Wet surface paper is obtained by pulp molding, and wet bottom paper is obtained by bottom pulp molding. The relative moisture content of the wet surface paper and the wet bottom paper is 55%. Composite antibacterial pulp layer is obtained by molding the composite antibacterial pulp obtained in step (2). The relative moisture content of the composite antibacterial pulp layer is 55%. 35g of superabsorbent resin is spread on the wet bottom paper to form a superabsorbent resin layer. Then the composite antibacterial pulp layer is laid on the superabsorbent resin layer. Finally, the wet surface paper is laid on the composite antibacterial pulp layer and wet-pressed to obtain a wet paper blank. The wet pressing is pressing at a pressure of 1.0MPa for 30s at room temperature.

[0067] Example 6 Example 6 is basically the same as Example 3, except that: (4) The wet paper blank is dried with hot air at 110°C until the relative moisture content of the wet paper blank is 6%, and then heat-treated at 90°C for 30 minutes. After cooling, it is cut to obtain zinc ricinoleate composite antibacterial absorbent paper.

[0068] Comparative Example 1 Comparative Example 1 is basically the same as Example 3, except that: (1) Add 0.8g of zinc ricinoleate to 70g of deionized water and ultrasonically disperse (ultrasonic dispersion power is 400W) for 20min. Then add 0.3g of polyoxyethylene dehydrated sorbitan monolaurate (Tween-20) and stir at 1000r / min for 40min to obtain zinc ricinoleate antibacterial solution.

[0069] In this comparative example, the zinc ricinoleate antibacterial solution was used to replace the compound antibacterial solution in Example 3 for subsequent steps (2) to (4).

[0070] Comparative Example 2 Comparative Example 2 is basically the same as Example 3, except that: (1) Add 0.8g zinc ricinoleate and 0.4g nano silica to 70g deionized water, and ultrasonically disperse (ultrasonic dispersion power is 400W) for 20min. Then add 0.3g polyoxyethylene sorbitan monolaurate (Tween-20) and stir at 1000r / min for 40min to obtain composite antibacterial solution.

[0071] In this comparative example, the composite antibacterial solution was used to replace the composite antibacterial solution in Example 3 for subsequent steps (2) to (4).

[0072] Comparative Example 3 Comparative Example 3 is basically the same as Example 3, except that: (1) Add 0.8g zinc ricinoleate, 0.32g nano silica and 0.08g silane coupling agent KH-550 to 70g deionized water, and ultrasonically disperse (ultrasonic dispersion power is 400W) for 20min. Then add 0.3g polyoxyethylene dehydrated sorbitan monolaurate (Tween-20) and stir at 1000r / min for 40min to obtain composite antibacterial solution.

[0073] In this comparative example, the composite antibacterial solution was used to replace the composite antibacterial solution in Example 3 for subsequent steps (2) to (4).

[0074] Comparative Example 4 (1) Add 0.8g zinc ricinoleate and 0.4g silane coupling agent KH-550 modified nano silica to 70g deionized water, and ultrasonically disperse (ultrasonic dispersion power is 400W) for 20min. Then add 0.3g polyoxyethylene dehydrated sorbitan monolaurate (Tween-20) and stir at 1000r / min for 40min to obtain composite antibacterial solution.

[0075] (2) Prepare a 10wt% plant fiber slurry by mixing 30g of plant fiber pulverized to 300 mesh with deionized water. Then add 0.5g of polyethylene glycol monostearate to the plant fiber slurry and stir at 800r / min for 10min to obtain a surface slurry. Prepare a 16wt% plant fiber slurry by mixing 30g of plant fiber pulverized to 300 mesh with deionized water. Then add 0.5g of polyethylene glycol monostearate to the plant fiber slurry and stir at 800r / min for 10min. min, to obtain the bottom layer slurry; then the surface layer slurry is used to form a wet surface paper, and the bottom layer slurry is used to form a wet bottom layer paper, the relative moisture content of the wet surface paper and the wet bottom layer paper is 55%; 35g of superabsorbent resin is spread on the wet bottom layer paper to form a superabsorbent resin layer, and then the composite antibacterial liquid obtained in step (1) is sprayed on the superabsorbent resin layer, and finally the wet surface paper is laid on the superabsorbent resin layer sprayed with the composite antibacterial liquid and wet pressed to obtain a wet paper blank; the wet pressing is pressing at a pressure of 1.0MPa for 30s at room temperature.

[0076] (3) The wet paper blank is dried with hot air at 110°C until the relative moisture content of the wet paper blank is 20%, and then heat-treated at 90°C for 30 minutes. After cooling, it is cut to obtain zinc ricinoleate composite antibacterial absorbent paper.

[0077] Comparative Example 5 Comparative Example 5 is basically the same as Example 3, except that: (3) Prepare a 10wt% plant fiber pulp by mixing 30g of plant fiber crushed to 300 mesh with deionized water as the surface pulp; prepare a 16wt% plant fiber pulp by mixing 30g of plant fiber crushed to 300 mesh with deionized water as the bottom pulp; then form a wet surface paper by molding the surface pulp and a wet bottom paper by molding the bottom pulp. The relative moisture content of the wet surface paper and the wet bottom paper is 55%. Form a composite antibacterial pulp layer by molding the composite antibacterial pulp obtained in step (2). The relative moisture content of the composite antibacterial pulp layer is 55%. Spread 35g of superabsorbent resin on the wet bottom paper to form a superabsorbent resin layer. Then lay the composite antibacterial pulp layer on the superabsorbent resin layer. Finally, lay the wet surface paper on the composite antibacterial pulp layer and wet press to obtain a wet paper blank. The wet pressing is pressing at 1.0MPa for 30s at room temperature.

[0078] The pore size of the surface layer of the zinc ricinoleate composite antibacterial absorbent paper prepared in this comparative example was measured to be 100~170μm, and the pore size of the bottom layer was measured to be 30~90μm.

[0079] Comparative Example 6 Comparative Example 6 is basically the same as Example 3, except that: (3) Prepare a 10wt% plant fiber slurry by mixing 30g of plant fiber pulverized to 300 mesh with deionized water. Then add 0.5g of polyethylene glycol to the plant fiber slurry and stir at 800r / min for 10min to obtain a surface slurry. Prepare a 16wt% plant fiber slurry by mixing 30g of plant fiber pulverized to 300 mesh with deionized water. Then add 0.5g of polyethylene glycol to the plant fiber slurry and stir at 800r / min for 10min to obtain a bottom slurry. Then use the surface slurry to form a... The wet top layer paper is formed by molding the bottom layer pulp, and the relative moisture content of the wet top layer paper and the wet bottom layer paper is 55%. The composite antibacterial pulp obtained in step (2) is used to form a composite antibacterial pulp layer, and the relative moisture content of the composite antibacterial pulp layer is 55%. 35g of superabsorbent resin is spread on the wet bottom layer paper to form a superabsorbent resin layer. Then the composite antibacterial pulp layer is laid on the superabsorbent resin layer. Finally, the wet top layer paper is laid on the composite antibacterial pulp layer and wet-pressed to obtain a wet paper blank. The wet pressing is pressing at a pressure of 1.0MPa for 30s at room temperature.

[0080] The pore size of the surface layer of the zinc ricinoleate composite antibacterial absorbent paper prepared in this comparative example was measured to be 70~130μm, and the pore size of the bottom layer was measured to be 25~75μm.

[0081] Comparative Example 7 Comparative Example 7 is basically the same as Example 3, except that: (4) The wet paper blank is dried with hot air at 110°C until the relative moisture content of the absorbent paper is 6%, and then cooled and cut to obtain zinc ricinoleate composite antibacterial absorbent paper.

[0082] Comparative Example 8 Comparative Example 8 is basically the same as Example 3, except that: (1) Add 0.8g of zinc ricinoleate and 0.4g of silane coupling agent KH-550 modified nano silica to 70g of deionized water and ultrasonically disperse (ultrasonic dispersion power is 400W) for 20min to obtain composite antibacterial solution.

[0083] (2) Take 60g of plant fiber and crush it to 300 mesh. Add 250g of deionized water to prepare plant fiber slurry. Add the composite antibacterial liquid obtained in step (1) in sequence. Stir at 800r / min for 15min. Then adjust the concentration of the composite antibacterial slurry to 15wt% and the pH to 7.5 to obtain the composite antibacterial slurry. This comparative example uses the composite antibacterial slurry to replace the composite antibacterial slurry in Example 3 for subsequent steps (3) and (4).

[0084] Comparative Example 9 (1) Prepare a 10wt% plant fiber slurry by mixing 30g of plant fiber pulverized to 300 mesh with deionized water. Then add 0.5g of polyethylene glycol monostearate to the plant fiber slurry and stir for 10min at 800r / min to obtain a surface slurry. Prepare a 16wt% plant fiber slurry by mixing 30g of plant fiber pulverized to 300 mesh with deionized water. Then add 0.5g of polyethylene glycol monostearate to the plant fiber slurry. The mixture was stirred at 800 r / min for 10 min to obtain a bottom layer slurry. Then, a wet top layer paper was formed using the top layer slurry, and a wet bottom layer paper was formed using the bottom layer slurry. The relative moisture content of the wet top layer paper and the wet bottom layer paper was 55%. 35 g of superabsorbent polymer (SAP) was spread on the wet bottom layer paper to form a SAP layer. Then, the wet top layer paper was laid on the SAP layer and wet-pressed to obtain a wet paper blank. The wet pressing was performed at a pressure of 1.0 MPa for 30 s at room temperature.

[0085] (2) The wet paper blank is dried with hot air at 110°C until the relative moisture content of the wet paper blank is 6%, and then it is cooled and cut to obtain absorbent paper.

[0086] The present invention conducted performance tests on the absorbent paper finally obtained in each embodiment and each comparative example. The test results are shown in Table 1 below, and the test methods are as follows: Antibacterial rate: The antibacterial rate against Escherichia coli and Staphylococcus aureus was tested according to the standard GB / T 20944.3-2008 "Oscillating Method". The antibacterial rate against Staphylococcus aureus was tested after the absorbent paper was subjected to 50 water washing-drying cycles. Each time, the paper was washed with 10 mL of physiological saline and then dried at 50 °C to constant weight.

[0087] Odor adsorption rate: Ammonia and n-butyric acid were used as simulated odor gases, and the gas concentrations before and after adsorption were tested by gas chromatography.

[0088] Absorption rate and reverse osmosis: Take 10 mL of physiological saline and inject it into the center area of ​​the flat absorbent paper at a uniform speed using a liquid addition device. Record the time required from the liquid surface contacting the physiological saline to the complete absorption of the liquid as the absorption rate (s). After standing for 5 min, cover the sample with a standard filter paper of known weight, press it with a 1.2 kg weight for 1 min, and weigh the increase in weight of the filter paper as the reverse osmosis amount (g).

[0089] Table 1 In Table 1, the symbol "-" indicates that the performance metric was not tested.

[0090] As shown in Table 1, the absorbent paper prepared in the preferred embodiment of the present invention maintains an antibacterial rate of over 95% after 50 washing-drying cycles, solving the problem of easy migration and loss of existing antibacterial agents. It achieves stable immobilization of antibacterial components with no significant component migration and exhibits excellent synergistic performance: absorbency ≥35g / g, odor adsorption rate ≥85%, and antibacterial rates against Escherichia coli and Staphylococcus aureus both exceeding 99%. Simultaneously, it demonstrates outstanding water-locking and anti-backflow effects, with no surface liquid accumulation or bottom backflow. The absorbent paper prepared by the present invention possesses excellent absorbency, antibacterial, deodorizing, and anti-backflow properties, meeting the core requirements of hygiene products. Furthermore, its preparation process is simple, demonstrating significant practical value and promising prospects for promotion.

[0091] As shown in Table 1, compared to Example 3, in Example 4, the amount of polyethylene glycol monostearate used in the hydrophilic modification treatment of the surface and bottom layers was too small. This may lead to uneven liquid distribution and poor water-locking ability due to the coarse pore structure, weakened gradient structure, and decreased interlayer bonding in the surface and bottom layers. Furthermore, it significantly slows down the absorption rate and increases the reverse osmosis. In addition, the uneven structure, weak interlayer bonding, and coarse pore structure also affect the stable adhesion and effective contact of the antibacterial components, thus also... This leads to a decrease in the long-lasting antibacterial rate and adsorption rate. Compared to Example 3, in Example 5, when the surface and bottom layers were hydrophilically modified, too much polyethylene glycol monostearate was used. It is possible that the excessive amount of polyethylene glycol monostearate interfered with the interfiber bonding, resulting in a relatively loose structure. Although the water absorption rate was enhanced, the loose structure led to a decrease in water retention capacity and an increase in backflow. Moreover, the relatively loose structure of the surface and bottom layers also reduced the retention capacity of the antibacterial components, resulting in a decrease in the long-lasting antibacterial rate and adsorption rate of the absorbent paper. Compared to Example 3, in Example 6, the excessive removal of moisture from the wet paper blank due to the high-temperature drying process caused the plant fibers and composite antibacterial components to lose their necessary molecular activity due to excessive dryness. The subsequent low-temperature heat treatment was unable to effectively promote the full and stable binding between the modified nano-silica and zinc ricinoleate network composite antibacterial system and the functional groups on the surface of the plant fibers. This resulted in a relatively poor fixation of the antibacterial components and a relatively deteriorated fiber network structure in the absorbent paper prepared therefrom. Ultimately, this manifested as a decrease in the absorbent paper's odor adsorption capacity, and after 50 cycles of washing and drying, the long-lasting antibacterial performance declined, resulting in a decrease in overall performance compared to Example 3.

[0092] Compared to Example 3, Comparative Example 1, lacking the addition of KH-550 modified nano-silica, relies solely on the physical adhesion between zinc ricinoleate and the fiber in its antibacterial system. It lacks an effective network structure formed by surface groups and zinc ricinoleate, leading to structural deterioration of the absorbent paper. This prevents the antibacterial components from being stably immobilized on the fiber substrate, resulting in migration and loss. Comparative Example 1's absorbent paper not only exhibits weak initial antibacterial and adsorption properties but also shows a significant decrease in antibacterial rate after 50 wash-dry cycles. Furthermore, due to insufficient fiber network support, its water absorption speed is slower, and its water retention performance (higher reverse seepage rate) is also weaker. The performance of the control group also decreased significantly. Compared with control group 1, control group 2 directly added nano-silica to the composite antibacterial system. The results showed that its various properties were only slightly improved compared with control group 1. This indicates that nano-silica without surface modification cannot form an effective network structure with zinc ricinoleate and cannot effectively immobilize functional components. Control group 3 directly added nano-silica and silane coupling agent KH-550 to the system at the same time. Its performance improvement was not significant. This also indicates that simply mixing nano-silica and silane coupling agent KH-550 cannot effectively achieve stable immobilization of antibacterial components.

[0093] Compared to Example 3, Comparative Example 4, which uses a process of directly spraying the composite antibacterial liquid onto the superabsorbent resin layer, has a significantly reduced antibacterial durability. This is because the lack of plant fiber as a binding substrate means that the antibacterial components can only be adsorbed onto the surface of the superabsorbent resin particles, while the superabsorbent resin layer has a relatively loose structure and weak binding force.

[0094] Compared to Example 3, in Comparative Example 5, since no hydrophilic modification was performed on the surface and bottom layers of the paper, a relatively large and loosely distributed pore structure was formed. This not only failed to increase the water absorption rate due to the increased pore size, but also slowed down liquid permeation due to weakened capillary action. Simultaneously, the large and unstable pore structure had weak water-locking ability, resulting in a high amount of backflow. Furthermore, the relatively uneven fiber dispersion weakened the fixation of the antibacterial components, and the poor interlayer bonding further affected the overall stability and functional durability of the structure. Compared to Example 3, Comparative Example 6 used polyethylene glycol for hydrophilic modification, which improved the hydrophilicity of the fibers to some extent, making its performance superior to the unmodified Comparative Example 5. However, the pore size gradient formed by polyethylene glycol was not precise enough, resulting in a lower liquid permeation rate and anti-backflow ability compared to Example 3. Similarly, in terms of antibacterial longevity, it could not effectively lock in the antibacterial components and inhibit their loss, leading to a decline in long-term antibacterial performance.

[0095] Compared to Example 3, Comparative Example 7 was dried directly at 110°C. This conventional one-step drying process resulted in a decrease in overall performance compared to Example 3. Compared to Example 3, Comparative Example 8 did not add dispersants or humectants, and its performance was inferior to Example 3 in all aspects. This may be because the agglomerates formed by uneven dispersion of antibacterial components may clog fiber pores, and the paper may become brittle during drying, leading to structural deterioration. The lack of dispersants caused severe agglomeration of antibacterial components, preventing them from functioning evenly and fully; while the lack of humectants made the paper brittle during the drying process, damaging the structural stability and uniformity of the composite antibacterial intermediate layer. As can be seen from the comparison between Example 3 and Comparative Example 9, this invention, through a unique synergistic modification process, successfully endowed the absorbent paper with long-lasting and highly efficient antibacterial and deodorizing functions without significantly affecting its core performance (still fast absorption speed and low backflow).

[0096] The parts of this invention not described in detail are techniques known to those skilled in the art.

[0097] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing zinc ricinoleate composite antibacterial absorbent paper, characterized in that, The method includes the following steps: (1) Disperse zinc ricinoleate and modified nano-silica with water using ultrasonication, then add a dispersant and stir evenly to obtain a composite antibacterial solution; (2) Use water to prepare plant fiber pulp, then add compound antibacterial liquid and humectant to the plant fiber pulp and stir evenly to obtain compound antibacterial pulp; (3) A super absorbent resin is spread on the wet bottom paper to form a super absorbent resin layer, and then a composite antibacterial pulp layer is laid on the super absorbent resin layer. Finally, a wet top paper is laid on the composite antibacterial pulp layer and wet-pressed to obtain a wet paper blank; the composite antibacterial pulp layer is formed by composite antibacterial pulp. (4) The wet paper blank is dried with hot air at 100~110℃ and treated at 80~90℃ for 20~30 minutes, and then cooled to obtain zinc ricinoleate composite antibacterial absorbent paper.

2. The preparation method according to claim 1, characterized in that: The modified nano-silica is silane coupling agent modified nano-silica; Preferably, the silane coupling agent is silane coupling agent KH-550; Preferably, the modified nano-silica has a particle size of 50~100nm.

3. The preparation method according to claim 1, characterized in that, The raw materials for preparing the composite antibacterial slurry contain the following components in parts by mass: 50-60 parts plant fiber, 0.2-0.8 parts zinc ricinoleate, 0.1-0.4 parts modified nano silica, 0.1-0.3 parts dispersant and 0.5-1.0 parts humectant.

4. The preparation method according to claim 1, characterized in that: In the zinc ricinoleate composite antibacterial absorbent paper, the mass ratio of the composite antibacterial slurry to the superabsorbent resin is (50~75):(25~50), preferably (50~75):(25~30). The dispersant is polyoxyethylene sorbitan monolaurate; and / or The moisturizer is glycerin.

5. The preparation method according to claim 1, characterized in that: The wet bottom paper is formed from a bottom pulp. Preferably, the bottom pulp is prepared by: mixing plant fibers with water to prepare a plant fiber pulp with a concentration of 12-16 wt%, and then adding polyethylene glycol monostearate to the plant fiber pulp and stirring evenly. The wet surface paper is formed from surface pulp. Preferably, the surface pulp is prepared by: mixing plant fibers with water to form a plant fiber pulp with a concentration of 8-10 wt%, and then adding polyethylene glycol monostearate to the plant fiber pulp and stirring evenly.

6. The preparation method according to claim 5, characterized in that: In the preparation of the bottom slurry and / or the top slurry, the mass ratio of polyethylene glycol monostearate to the plant fiber contained in the plant fiber slurry is (0.3~0.5):(20~30).

7. The preparation method according to claim 1, characterized in that: The superabsorbent resin is a polyacrylate superabsorbent resin and / or an acrylate-acrylamide copolymer; Preferably, the polyacrylate superabsorbent resin is sodium polyacrylate superabsorbent resin.

8. The preparation method according to claim 1, characterized in that: In step (1), the power of the ultrasonic dispersion is 300~400W, and the ultrasonic dispersion time is 15~20min; In step (1), the stirring speed is 800~1000 r / min, and the stirring time is 30~40 min; In step (2), the concentration of the composite antibacterial slurry is adjusted to 10-15 wt%. In step (2), the pH of the composite antibacterial slurry is adjusted to 6.5~7.5; and / or In step (2), the stirring speed is 600~800 r / min, and the stirring time is 5~15 min.

9. Zinc ricinoleate composite antibacterial absorbent paper prepared by any one of claims 1 to 8.

10. The application of zinc ricinoleate composite antibacterial absorbent paper prepared by any one of claims 1 to 8 in hygiene products; Preferably, the sanitary products are one or more of sanitary napkins, diapers, and nursing pads; More preferably, the zinc ricinoleate composite antibacterial absorbent paper serves as the absorbent and antibacterial layer of the hygiene product.

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