A cleaning sheet and a method for manufacturing the same, and use thereof

Abstract

This application relates to the field of detergent technology, providing a cleaning sheet, its preparation method, and its application. The cleaning sheet comprises a primary layer, a secondary layer, and a final layer stacked sequentially. The primary layer includes a surfactant and a disintegrant; the secondary layer includes immobilized enzyme microspheres and a cleaning aid; and the final layer includes an alkali source and sodium percarbonate particles coated with an acidic substance. The immobilized enzyme microspheres include a core layer and a shell layer. The core layer comprises an alginate gel and an enzyme embedded in the alginate gel, and the shell layer comprises chitosan. This application, through a combination of physical isolation and core-shell immobilization, effectively reduces the mutual damage between the enzyme and the oxidant, improves the enzyme activity retention rate and the stability of sodium percarbonate, and achieves a synergistic cleaning effect of rapid foaming and delayed bleaching. It is suitable for kitchen countertops, sanitary ware, tiles, and other hard surfaces.

Description

Technical Field

[0001] This application relates to the field of detergent technology, and in particular to a cleaning tablet, its preparation method, and its application. Background Technology

[0002] With increasing hygiene requirements in homes and public places, mold and the resulting black stains have become a significant challenge in the field of hard surface cleaning. Traditional cleaning systems typically rely on surfactants, enzymatic degraders, and oxidative bleaching agents, each performing its specific function: surfactants handle interface cleaning, enzymes catalyze the breakdown of protein and polysaccharide organic stains, and solid oxidants provide bleaching and disinfection. Integrating these functional modules into convenient solid tablets allows for cleaning, degradation, and bleaching in a single application, thus meeting consumers' expectations for high efficiency, economy, and ease of use.

[0003] However, current commercially available mold removal solutions, which mainly rely on high-concentration chemical bactericides or single strong oxidants, have shortcomings in addressing the key technical issues of biofilm destruction and deep black spot removal. Strong oxidizing or strong alkaline formulations struggle to penetrate the biofilm matrix composed of chitin, extracellular polysaccharides, and proteins, failing to effectively contact and decompose mold cells and melanin hidden within the matrix, resulting in incomplete surface cleaning and requiring prolonged action. On the other hand, highly active chemicals pose risks of corrosion and discoloration to the substrate, as well as significant residue and environmental burden. Furthermore, many formulations have limited functionality and are prone to bulging and gas production during storage and transportation due to deliquescence or peroxide decomposition, resulting in poor overall user experience and stability, failing to simultaneously achieve deep cleaning effects and meet safety and environmental protection requirements.

[0004] Therefore, there is an urgent need to develop a cleaning tablet and its preparation method to solve the above problems. Summary of the Invention

[0005] In view of the above-mentioned shortcomings in the prior art, the purpose of this application is to provide a cleaning tablet, its preparation method, and its application.

[0006] To achieve the above-mentioned objectives, the technical solution adopted in this application is as follows: In a first aspect, embodiments of this application provide a cleaning sheet comprising a primary layer, a secondary layer, and a final layer formed by sequentially stacking layers; the primary layer comprises a surfactant and a disintegrant; the secondary layer comprises immobilized enzyme microspheres and a cleaning aid component; and the final layer comprises an alkali source and sodium percarbonate particles coated with an acidic substance; wherein the immobilized enzyme microspheres comprise a core layer and a shell layer, the core layer comprising an alginate gel and an enzyme embedded in the alginate gel, and the shell layer comprising chitosan.

[0007] In an optional embodiment, the acidic substance includes at least one of citric acid and citrate; and / or the alkali source includes at least one of sodium carbonate, sodium bicarbonate, and sodium silicate; and / or the detergent building agent includes at least one of tetraacetylethylenediamine, sodium citrate, and sodium sulfate; and / or the surfactant includes at least one of rhamnolipid and alkyl polyglycoside; and / or the disintegrant includes at least one of croscarmellose sodium, croscarmellose, and croscarmellose starch.

[0008] In one alternative implementation, the coating mass of the acidic substance is 1-10 wt% based on the total weight of the sodium percarbonate particles.

[0009] In an optional embodiment, the immobilized enzyme microspheres have a particle size of 50-200 μm; and / or the enzyme loading is 0.3-5 wt% based on the total dry weight of the immobilized enzyme microspheres.

[0010] Secondly, embodiments of this application provide a method for preparing a cleaning tablet. The method is used to prepare any of the above-mentioned cleaning tablets and includes the following steps: S100, preparing immobilized enzyme microspheres; S200, layering and compressing a primary layer material including a surfactant and a disintegrant, a secondary layer material including immobilized enzyme microspheres and a washing aid component, and a final layer material including an alkali source and sodium percarbonate particles into a tablet to obtain a cleaning tablet.

[0011] In an optional implementation, step S100 specifically includes the following steps: S110, mixing the enzyme with sodium alginate solution to obtain a mixture; S120, adding the mixture to a calcium ion solution for cross-linking and curing treatment to form enzyme-loaded calcium alginate gel microspheres; S130, contacting the enzyme-loaded calcium alginate gel microspheres with a chitosan solution to obtain immobilized enzyme microspheres.

[0012] In an optional embodiment, step S130 is followed by: S140, lyophilizing the immobilized enzyme microspheres or vacuum drying at a low temperature below 40°C.

[0013] In an optional implementation, in step S200, sodium percarbonate particles are obtained by fluidized bed spray coating, which includes spraying a solution containing an acidic substance with a pH of 2.0-3.5 onto the surface of the sodium percarbonate particles.

[0014] In an optional implementation, in step S200, the delamination and tableting are performed in an inert gas atmosphere, and a delamination and tableting mold is used to apply different tableting pressures to the initial layer, intermediate layer and final layer respectively; wherein, the pressure of the initial layer is 5-30kN; the pressure of the intermediate layer is 5-20kN; and the pressure of the final layer is 10-50kN.

[0015] Thirdly, this application provides an application of a cleaning sheet, in which any of the above-mentioned cleaning sheets is applied to the cleaning treatment of hard surfaces, including kitchen countertops, sanitary ware, tiles, or hard furniture surfaces.

[0016] The beneficial effects of this application include at least the following: (1) Through the three-layer structure design and the core-shell structure of the immobilized enzyme microspheres, physical isolation and sequential release of enzyme and oxidant were achieved, which improved the enzyme activity preservation rate and the storage stability of sodium percarbonate. (2) The rapid disintegration of the primary layer and the surfactant provide immediate cleaning power, the slow-release enzyme system of the intermediate layer can effectively decompose the biofilm, and the delayed bleaching effect of the final layer can completely remove pigments, thus achieving a synergistic and efficient cleaning effect. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings to be used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort: Figure 1 This is a physical image of Embodiment 1 of this application; Figure 2 This is a comparison image of cleaning mold stains at room temperature before and after Example 1; Figure 3 Comparative Example 6: Before and after photos of cleaning mold stains at room temperature. Detailed Implementation

[0018] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with embodiments. It should be understood that the specific embodiments described herein are only for explaining this application, but the implementation of this application is not limited thereto.

[0019] Unless otherwise defined, the technical terms used in the following embodiments have the same meanings as commonly understood by those skilled in the art to which this application pertains. Unless otherwise specified, the experimental reagents used in the following embodiments are conventional biochemical reagents; the amounts of experimental reagents used are, unless otherwise specified, the amounts used in conventional experimental operations; and the experimental methods used are, unless otherwise specified, conventional methods.

[0020] With increasing hygiene requirements in homes and public places, mold and the black stains it forms have become a significant challenge in the field of hard surface cleaning. Existing mold removal solutions mostly rely on surfactants, enzymatic degradation agents, or high-concentration chemical bactericides and strong oxidants. However, these single or simple combinations of formulations struggle to penetrate the mold biofilm composed of chitin, extracellular polysaccharides, and proteins, resulting in limited effectiveness in removing deep stains and melanin. Furthermore, strong oxidizing or alkaline formulations pose problems such as substrate corrosion, residual contamination, and storage instability. Therefore, there is an urgent need to develop a cleaning sheet and its preparation method to address these issues.

[0021] In view of the above-mentioned shortcomings in the prior art, the purpose of this application is to provide a cleaning tablet, its preparation method, and its application.

[0022] In a first aspect, embodiments of this application provide a cleaning sheet, which includes a primary layer, a secondary layer, and a final layer stacked sequentially. The initial layer includes surfactants and disintegrants; The intermediate layer consists of immobilized enzyme microspheres and washing aid components; The final layer includes an alkali source and sodium percarbonate particles coated with acidic substances. The immobilized enzyme microspheres include a core layer and a shell layer. The core layer includes an alginate gel and an enzyme embedded in the alginate gel, while the shell layer includes chitosan.

[0023] Preferably, the cleaning tablet provided in this application embodiment adopts a three-layer structure of primary layer, intermediate layer and final layer stacked sequentially along the thickness direction. Through the synergistic strategy of spatial isolation and sequential dissolution, the surfactant system, enzyme system and oxidative bleaching system can be compatible and coexist and sequentially activated in the same tablet.

[0024] Upon contact with water, the primary layer preferentially and rapidly disintegrates under the action of the disintegrant. The surfactant quickly reduces the liquid-solid interfacial tension and wets the substrate surface, achieving preliminary emulsification and removal of oil and loose dirt, creating channels for subsequent penetration and action on the biofilm. Subsequently, the intermediate layer swells or slowly disintegrates. Under the dual barrier protection of the alginate gel core and chitosan shell, the immobilized enzyme microspheres release enzyme preparations in a controlled manner, targeting and hydrolyzing structural components such as proteins and polysaccharides in the biofilm, thereby weakening the biofilm skeleton and reducing its adhesion. At the same time, the cleaning aid components in the intermediate layer can play a pre-treatment role such as complexation, dispersion, or activation before the release of reactive oxygen species in the final layer.

[0025] Finally, the sodium percarbonate particles in the final layer are coated with an acidic substance. This coating forms a continuous film on the particle surface, reducing direct contact between the sodium percarbonate and ambient moisture, thus mitigating the risk of self-decomposition due to deliquescence. Simultaneously, citric acid and / or citrate have a complexing effect on trace metal ions, reducing the catalytic effect of metal ions on peroxide decomposition and improving effective oxygen retention and shelf stability. During use, the coating hinders moisture entry into the particles and, in conjunction with the dense structure formed under high compression force in the final layer, reduces porosity and slows liquid penetration. This ensures that the sodium percarbonate core is not immediately exposed before the coating completes hydration, swelling, and gradual dissolution, resulting in a relatively delayed release.

[0026] Furthermore, after the coating layer dissolves, acidic substances preferentially neutralize the alkaline source in the final layer, consuming some alkalinity and forming a temporary pH buffer, thereby delaying the rapid establishment of a strongly alkaline environment. Before the strongly alkaline environment is established, the instantaneous release rate of the reactive oxygen species system is relatively reduced, resulting in a delayed start-up of bleaching and sterilization effects. When the alkaline source is carbonate or bicarbonate, the neutralization process may be accompanied by CO2 generation, which helps with liquid film renewal and stain removal. When the alkaline source is silicate, no CO2 is generated, but delayed release can still be achieved through the dense structure and pH buffering effect.

[0027] Furthermore, the surfactants include at least one of rhamnolipids and alkyl polyglycosides; these surfactants can rapidly reduce liquid-solid interfacial tension, emulsify greases, and promote the removal of loose dirt from the substrate; compared with traditional strong alkaline or anionic surfactants, rhamnolipids and alkyl polyglycosides have good wetting, detergency, and environmental compatibility, and produce moderate foam and are easy to rinse, which is beneficial to user experience and rapid rinsing. The disintegrants include at least one of croscarmellose sodium, croscarmellose, and croscarmellose starch; these disintegrants are used to rapidly absorb water and swell after the outer layer comes into contact with water, generating volume expansion force and breaking the outer layer structure, thereby achieving rapid separation of the tablet and ensuring that the intermediate and final layers are exposed and function in the predetermined sequence.

[0028] Preferably, the intermediate layer comprises immobilized enzyme microspheres with a core-shell structure and a cleaning aid component; the cleaning aid component comprises at least one of tetraacetylated ethylenediamine (TAED), sodium citrate, and sodium sulfate. Sodium citrate can act as a complexing and dispersing cleaning aid to complex metal ions, reducing the risk of peroxide decomposition caused by metal catalysis and inhibiting scaling; sodium sulfate can act as an inorganic cleaning salt to adjust ionic strength and improve dissolution dispersion and tableting performance; TAED can act as a bleaching activating component, generating more reactive oxide species such as peroxycarboxylic acid under certain conditions in the presence of hydrogen peroxide, thereby improving the utilization efficiency of active oxygen under low or medium temperature conditions and enhancing bleaching and sterilization effects.

[0029] It should be noted that the immobilized enzyme microspheres include a core layer and a shell layer. The core layer includes an alginate gel and an enzyme embedded in the alginate gel, and the shell layer includes chitosan. The enzymes include at least one of chitinase, β-glucanase, endoglucanase, protease, and DNase. Among them, chitinase can hydrolyze chitin in the fungal cell wall to destroy the cell wall integrity; β-glucanase and endoglucanase synergistically decompose the cell wall matrix and glucan components in the extracellular polysaccharide, weakening the physical framework of the biomembrane; protease and DNase respectively degrade the protein matrix and extracellular DNA network in the biomembrane, thereby weakening the adhesion and structural stability of the biomembrane. Through the synergistic effect of the multi-enzyme system, the dense three-dimensional structure of the biomembrane can be destroyed from multiple target sites, making it loose and easier to detach from the substrate surface. The core-shell structure provides dual protection for the enzyme. The alginate gel core and the chitosan shell together form a physical barrier, effectively isolating the external environment. At the same time, as a micro-sustained-release carrier, this structure can regulate the enzyme release rate through the diffusion restriction effect of the gel network, thereby prolonging the action time and enhancing the sustained enzymatic hydrolysis effect on biomembranes.

[0030] In an optional embodiment, the intermediate layer material includes immobilized enzyme microspheres and a washing aid component, and the intermediate layer material can be prepared as an enzyme-loaded hydrogel preform. The enzyme-loaded hydrogel preform includes a hydrogel matrix and immobilized enzyme microspheres and a washing aid component dispersed in the hydrogel matrix. Specifically, the washing aid component and immobilized enzyme microspheres, accounting for 10-40 wt% of the dry solids of the preform, are dispersed in the hydrogel matrix material, coated and molded, and dried and shaped at low temperature to obtain the enzyme-loaded hydrogel preform. The flexible hydrogel matrix can effectively disperse and absorb mechanical pressure during layered tableting, acting as a stress buffer layer, significantly reducing the risk of breakage or deformation of the internal brittle enzyme microspheres due to direct force, thereby maximizing the protection of enzyme activity during processing. Secondly, the solid preform shape facilitates precise positioning, filling, and metering in the tableting mold, ensuring high uniformity in the thickness of the intermediate layer, microsphere distribution, and enzyme content in each cleaning tablet product, greatly improving batch-to-batch consistency and quality reliability. The hydrogel matrix materials include hydroxypropyl methylcellulose and sodium carboxymethyl cellulose. Hydroxypropyl methylcellulose exhibits good film-forming properties and strong adhesion, providing controllable swelling behavior. Sodium carboxymethyl cellulose expands rapidly upon contact with water, forming a porous network of channels that regulates the kinetics of water penetration and enzyme molecule diffusion, which is crucial for achieving controlled enzyme release and extending the duration of action. In summary, this preform can be independently dried and shaped, isolating the intermediate-efficiency layer enzyme from the final-efficiency layer sodium percarbonate before tableting. This reduces the risk of interference between active ingredients during storage, further ensuring the long-term stability of the product over its shelf life. The proportion of microspheres in the preform is limited to 10-40 wt%. Too low a proportion will result in insufficient overall enzyme activity in the intermediate-efficiency layer, affecting cleaning efficiency; too high a proportion will weaken the continuity and structural strength of the hydrogel matrix, making it difficult to shape and prone to breakage, thus losing its core functions as a protective carrier and sustained-release unit. This preferred range ensures that the preform simultaneously possesses good mechanical integrity, processability, and efficient functional activity loading.

[0031] Furthermore, the immobilized enzyme microspheres have a particle size of 50-200 μm. This range provides optimal flowability and density during granulation and tableting processes. Particles that are too small are prone to compaction or agglomeration, leading to breakage and enzyme leakage during tableting. Particles that are too large can affect interlayer uniformity and cause interfacial defects or tablet breakage. The 50-200 μm size ensures a suitable diffusion path, maintaining a certain level of sustained release and protection while ensuring sufficiently rapid substrate infiltration and product diffusion during use, balancing reaction rate and enzyme protection. This also facilitates the formation of a good dispersed phase in the carrier matrix. Based on the total dry weight of the immobilized enzyme microspheres, the enzyme loading is 0.3-5 wt%, providing the specific activity required for cleaning efficiency while avoiding the increased cost and enzyme instability issues associated with excessively high enzyme concentrations.

[0032] Preferably, the final layer includes an alkali source and sodium percarbonate particles coated with an acidic substance, wherein the acidic substance includes at least one of citric acid and citrate; the alkali source includes at least one of sodium carbonate, sodium bicarbonate, and sodium silicate; the purpose of the coating is not to directly promote oxidation during storage, but to achieve stable storage and controlled release of sodium percarbonate by forming a dual physical and chemical barrier. First, the acidic coating reduces direct contact between the particle surface and ambient moisture, and passivates trace metal impurities on the particle surface through the complexation of citric acid and citrate, thereby reducing the risk of catalytic decomposition of metals. Second, substances such as citric acid have weak complexing ability, which can integrate trace metal impurities on the particle surface, further reducing the risk of catalytic decomposition. Third, the coating can delay the direct mixing of sodium percarbonate with the surrounding alkaline source or water. During use, as the primary and secondary layers disintegrate and dissolve, the acidic substances are gradually dissolved or neutralized by alkali, thereby achieving delayed dissolution of sodium percarbonate and achieving a delayed bleaching effect. In addition, the alkaline source of the final layer can quickly establish and maintain an alkaline reaction environment after the coating dissolves. This environment not only maximizes the bleaching efficiency of peroxides, but also plays an auxiliary role in saponifying and removing any residual grease stains that may remain during the cleaning process.

[0033] Furthermore, based on the total weight of sodium percarbonate particles, the coating mass of acidic substances is 1-10 wt%. Within this mass range, a continuous and not excessively thick protective film can be formed, sufficient to isolate moisture and impurities. If the coating acid content is too high, the acid will neutralize the alkali source prematurely or significantly reduce the release of effective peroxides of sodium percarbonate during use, thereby weakening the bleaching effect. If the coating amount is too low, the film layer may be incomplete, and the protective effect will be limited. Controlling the coating mass to 1-10 wt% can ensure the protective and complexing effects while avoiding significant acid-base neutralization side effects at normal usage dosages. This range makes it easy to obtain a stable and uniform coating through industrial coating processes such as fluidized bed spraying, and it is also economical in terms of raw materials and energy consumption.

[0034] Furthermore, the thickness of the initial layer is 0.6-1.2 mm, the thickness of the intermediate layer is 1.8-3.6 mm, and the thickness of the final layer is 2.4-6.0 mm. Secondly, embodiments of this application provide a method for preparing a cleaning tablet, the method being used to prepare any of the above-mentioned cleaning tablets, comprising the following steps: S100, Preparation of immobilized enzyme microspheres; S200: The primary layer material, including surfactants and disintegrants, the intermediate layer material, including immobilized enzyme microspheres and washing aids, and the final layer material, including alkali source and sodium percarbonate particles, are layered and compressed into tablets to obtain cleaning tablets.

[0035] Preferably, the preparation method of this application embodiment physically isolates multiple incompatible active components in space and sequentially activates them in time, ultimately integrating them into a cleaning tablet. First, immobilized enzyme microspheres with a core-shell protective structure are prepared independently, then delayed-release sodium percarbonate particles with an acidic coating layer are prepared separately, and finally, a layered tableting process is used to obtain the cleaning tablet. This method successfully solves the long-standing technical problems of easy enzyme inactivation, unstable oxidant, and mutual interference between components in the production of traditional cleaning agents, providing a reliable and scalable process route for the production of high-performance, long-shelf-life solidified cleaning products.

[0036] Furthermore, step S100 specifically includes the following steps: S110. Mix the enzyme with sodium alginate solution to obtain a mixture; S120. The mixture is added to a calcium ion solution for cross-linking and curing treatment to form enzyme-loaded calcium alginate gel microspheres. S130. Contact the enzyme-loaded calcium alginate gel microspheres with chitosan solution to obtain immobilized enzyme microspheres.

[0037] Preferably, in step S110, the enzyme is mixed with a sodium alginate solution of 1.0-4.0 wt% to provide a mild hydrophilic environment for the enzyme, initially dispersing and encapsulating it in an anionic polysaccharide chain network; in step S120, the mixture is added to a calcium ion solution of 0.01-0.2 M for cross-linking and solidification treatment for 5-30 min. In the presence of calcium ions, sodium alginate rapidly forms a three-dimensional cross-linked gel network, mechanically and spatially encapsulating the enzyme within the gel pores, restricting enzyme molecule migration and direct contact with external oxidants, thereby achieving chemical... The gel core provides primary protection to the enzyme both physically and chemically. It also forms a controllable diffusion resistance, allowing for regulation of the mass transfer rate between the substrate and product, thus achieving sustained release and prolonged reaction time. In step S130, the enzyme-loaded calcium alginate gel microspheres are contacted with a 1.0-2.0 wt% chitosan solution. Under weakly acidic conditions, chitosan undergoes electrostatic and polyelectrolyte complexation with the alginate surface, forming a dense shell. This shell further enhances the mechanical strength and pressure resistance of the microspheres, reduces the rate of moisture infiltration, and acts as a second chemical barrier to slow down the contact between oxidants and the enzyme. Furthermore, the core-shell structure facilitates control over the surface charge and hydrophilicity / hydrophobicity of the microspheres, thereby adjusting their dispersibility in the carrier matrix and their wetting and swelling behavior in water.

[0038] Furthermore, after step S130, the process includes: S140, freeze-drying the immobilized enzyme microspheres or low-temperature vacuum drying below 40°C; this step can reduce the residual moisture in the microspheres, thereby reducing the risk of catalytic decomposition of oxidants such as sodium percarbonate by moisture and extending the shelf stability of the enzyme and oxidant; freeze-drying forms a porous solid microstructure, maintaining or improving the pore network of the microspheres, so that they can quickly absorb water and swell upon rehydration and restore good mass transfer channels, ensuring the reaction rate of the enzyme during use; sublimation drying under low temperature and vacuum can remove moisture without thermal denaturation, and can better maintain the tertiary structure and catalytic activity of the enzyme than drying at room temperature; at the same time, controlling the drying temperature and residual moisture can reduce protein denaturation or loss of activity caused by drying.

[0039] Preferably, in step S200, sodium percarbonate particles are prepared by fluidized bed spray coating. Fluidized bed spray coating includes: spraying a solution containing acidic substances with a pH of 2.0-3.5 onto the surface of sodium percarbonate particles, and evaporating to form an acidic coating. This preparation method provides uniform and controllable coating, ensuring that the coating mass is within the range of 1-10 wt%, thus guaranteeing batch consistency. The process is also gentle, avoiding overheating that could lead to the decomposition of sodium percarbonate. Furthermore, the coating layer acts as a dual physical and chemical barrier during storage, isolating moisture and catalytic impurities, and achieving delayed release of sodium percarbonate through dissolution. In addition, unlike simply adding free acid to the formulation, the coating process fixes the acid on the particle surface from the preparation stage, avoiding the early impact of free acid on enzymes or other sensitive components during mixing, tableting, and storage.

[0040] Preferably, in step S200, the layered tableting is performed in an inert gas atmosphere, and the layered tableting uses a layered tableting mold to apply different tableting pressures to the initial layer, intermediate layer and final layer respectively. The pressure of the initial layer is 5-30 kN; the pressure of the intermediate layer is 5-20 kN; and the pressure of the final layer is 10-50 kN.

[0041] Furthermore, using inert gas in the layered tableting process can reduce the risk of oxidants being decomposed by moisture in the air or oxidative catalysts, and reduce the impact of heat, friction or localized humidity increase generated during the tableting process on enzyme or oxidant activity; inert gas can eliminate or dilute oxygen and water vapor, slowing down the oxidation reaction rate; and reduce the probability of contact between metal ions or catalysts in the air in the tableting chamber, thereby protecting sensitive components.

[0042] Furthermore, a layered tableting mold is used, and different compression pressures are applied to the primary, intermediate, and final layers. Applying a pressure of 5-30 kN to the primary layer not only ensures proper forming but also avoids over-compaction, thus maintaining appropriate porosity to ensure rapid disintegration upon contact with water. Applying a lower pressure of 5-20 kN to the intermediate layer minimizes mechanical stress on the internally brittle immobilized enzyme microspheres while maintaining interlayer bonding, preventing their rupture and enzyme activity loss. Applying a higher pressure of 10-50 kN to the final layer helps increase the density of this layer and the overall mechanical strength of the tablet. At the same time, its dense structure can slightly delay water penetration, synergistically achieving delayed release with the particle coating.

[0043] Thirdly, this application provides an application of a cleaning sheet, in which any of the above-mentioned cleaning sheets is applied to the cleaning treatment of hard surfaces, including kitchen countertops, sanitary ware, tiles, or hard furniture surfaces.

[0044] Preferably, after the cleaning tablet is placed in water, the initial layer disintegrates first, releasing surfactants to quickly wet and initially loosen surface dirt. Subsequently, the intermediate layer slowly releases various enzymes that target and hydrolyze structural components such as proteins, polysaccharides, and lipids in the biofilm, causing them to disintegrate and peel off. Finally, the final layer releases peroxides that oxidize, bleach, and disinfect in an alkaline environment, thoroughly removing pigments and killing residual microorganisms. This process overcomes the technical shortcomings of traditional single-phase cleaning agents, which cannot effectively penetrate and disintegrate the biofilm structure. Compared with directly using high-concentration strong acids, strong alkalis, or chlorine bleach, this cleaning tablet avoids prolonged and severe chemical corrosion of the cleaned surface, reducing the risk of damage to the substrate while ensuring the effectiveness of mold removal and stain removal. Furthermore, the tablet form is convenient to carry, store, and use in measured quantities, avoiding problems such as leakage, splashing, or inaccurate measurement of liquid cleaning agents.

[0045] This application has undergone multiple experiments, and some of the test results are presented here for reference to further describe the invention in detail. The following is a detailed description in conjunction with specific embodiments.

[0046] Example 1 This embodiment provides a cleaning tablet and its preparation method, including the following steps: S110. Select chitinase, β-glucanase, endoglucanase, protease and DNase. Based on the total dry weight of the immobilized enzyme microspheres, mix 3.0 wt% of the enzyme dry weight with 2.0 wt% sodium alginate solution to obtain a mixture. S120. The mixture was atomized into a 0.1M calcium chloride solution using a dual-fluid atomizing nozzle for cross-linking and curing for 10 minutes. After washing three times, enzyme-loaded calcium alginate gel microspheres were formed. The nozzle orifice diameter was 0.3 mm, the atomizing pressure was 0.10 MPa, the spraying distance was 15 cm, and the resulting microspheres had a particle size D50 of approximately 100 μm. S130. Immerse the enzyme-loaded calcium alginate gel microspheres in a 1.5 wt% chitosan solution, adjust the pH to 5.0 with acetic acid, gently shake for 10 min, and wash with deionized water to obtain immobilized enzyme microspheres. S140. The immobilized enzyme microspheres are first frozen at -40℃ for 4 hours, and then freeze-dried in a freeze dryer until the residual moisture is ≤3wt%. After grading and sieving, the dried immobilized enzyme microspheres are obtained. Preparation of enzyme-loaded hydrogel preforms: Based on the total dry solids of the preforms, 2wt% TAED, 2wt% sodium citrate, 2wt% sodium sulfate, and 24wt% dried immobilized enzyme microspheres were added, with the remainder being the hydrogel matrix. The dry solids composition of the hydrogel matrix included hydroxypropyl methylcellulose (HPMC), sodium carboxymethyl cellulose (CMC-Na), microcrystalline cellulose, and glycerol, with a mass ratio of HPMC, CMC-Na, microcrystalline cellulose, and glycerol of 35:15:15:1. The hydrogel matrix raw materials were added to deionized water to prepare a matrix slurry, and then TAED, sodium citrate, sodium sulfate, and dried immobilized enzyme microspheres were added. The mixture was stirred under low shear until homogeneous and then degassed. Subsequently, the slurry was coated onto a release film using a scraper, with the wet film thickness controlled at 1.5 mm, and dried in a 30℃ forced-air drying oven until the residual moisture content was 5wt%. Finally, the preforms were sliced ​​to obtain the enzyme-loaded hydrogel preforms. Preparation of sodium percarbonate particles: 250-500μm sodium percarbonate particles were fluidized in a fluidized bed at a bed temperature of 45℃. Citric acid aqueous solution with pH value of 2.5 and solid content of 10wt% was spray-coated, and the coating mass was controlled to be 5wt%. After coating, the particles were cooled and sieved to obtain sodium percarbonate particles coated with citric acid. S200: Using a layered tableting mold, under a nitrogen atmosphere, a primary layer powder consisting of 10 wt% rhamnolipin and 25 wt% croscarmellose sodium, with the remainder being sodium sulfate, is uniformly mixed and filled into the mold cavity. A pre-compression of 15 kN is applied to form a stable bottom layer. Then, an enzyme-loaded hydrogel pre-formed tablet is placed inside, and pressure is applied again to 10 kN. Finally, sodium carbonate and the aforementioned sodium percarbonate particles coated with citric acid are filled into the mold cavity as the final layer material. A pressure of 30 kN is applied and held for 2 seconds, after which the tablet is demolded to obtain a clean tablet. Figure 1 As shown.

[0047] Example 2 This embodiment provides a compound enzyme anti-mold cleaning tablet and its preparation method. The preparation method of the cleaning tablet is the same as that shown in Embodiment 1, except that: In step S110, chitinase powder, β-glucanase powder and protease powder are selected, and 0.5 wt% of enzyme dry weight is mixed with 1.0 wt% sodium alginate solution. In step S120, a cross-linking curing treatment was performed in a calcium chloride solution with a concentration of 0.01M for 30 minutes, wherein the nozzle orifice diameter was 0.2 mm and the atomizing gas pressure was 0.18 MPa. The resulting microspheres were tested for particle size and the D50 was approximately 50 μm. In step S130, the concentration of the chitosan solution is 1.0 wt%; In step S140, the immobilized enzyme microspheres are dried at 35°C and 10 mbar for 24 h under low temperature vacuum, and then sieved to obtain the dried immobilized enzyme microspheres. In the preparation of enzyme-loaded hydrogel preforms, 1 wt% TAED, 1 wt% sodium citrate, 1 wt% sodium sulfate, and 7 wt% dried immobilized enzyme microspheres were used as the carrier materials, which were 30 wt% HPMC, 10 wt% CMC-Na, and 20 wt% microcrystalline cellulose.

[0048] Example 3 This embodiment provides a compound enzyme anti-mold cleaning tablet and its preparation method. The preparation method of the cleaning tablet is the same as that shown in Embodiment 1, except that: In step S110, 5.0 wt% of the enzyme dry weight is mixed with 4.0 wt% sodium alginate solution; In step S120, a cross-linking curing treatment was performed in a calcium chloride solution with a concentration of 0.2M for 10 minutes, wherein the nozzle orifice diameter was 0.5mm and the atomizing gas pressure was 0.08MPa. The resulting microspheres were tested for particle size and the D50 was approximately 200μm. In step S130, the chitosan solution concentration is 2.0 wt%; In the preparation of enzyme-loaded hydrogel preforms, 3wt% TAED, 3wt% sodium citrate, 3wt% sodium sulfate, and 31wt% dried immobilized enzyme microspheres were used.

[0049] Example 4 This embodiment provides a compound enzyme anti-mold cleaning tablet and its preparation method. The preparation method of the cleaning tablet is the same as that shown in Embodiment 1, except that: In the preparation of sodium percarbonate particles, the bed temperature was fluidized at 55℃, and a citric acid aqueous solution with a pH of 3.5 was spray-coated, with the coating mass controlled at 1 wt%. In step S200, sodium bicarbonate is used as the alkali source in the final layer.

[0050] Example 5 This embodiment provides a compound enzyme anti-mold cleaning tablet and its preparation method. The preparation method of the cleaning tablet is the same as that shown in Embodiment 1, except that: In the preparation of sodium percarbonate particles, fluidization was carried out at a bed temperature of 35℃, and a compound solution of citric acid and sodium citrate with a pH of 2.0 was spray-coated, with the coating mass controlled at 10 wt%. In step S200, sodium silicate is used as an alkali source in the final layer.

[0051] Example 6 This embodiment provides a compound enzyme anti-mold cleaning tablet and its preparation method. The preparation method of the cleaning tablet is the same as that shown in Embodiment 1, except that: There is no step in preparing enzyme-loaded hydrogel preforms; that is, no preforms are used. Instead, TAED, sodium citrate, sodium sulfate, and dried immobilized enzyme microspheres are directly mixed with a small amount of microcrystalline cellulose as the intermediate layer powder. In step S200, 12 wt% alkyl polysaccharide and 25 wt% cross-linked carboxymethyl starch are mixed evenly to form a primary layer powder, and the pressure parameters are: 30 kN for the primary layer, 20 kN for the intermediate layer, and 50 kN for the final layer.

[0052] Example 7 This embodiment provides a compound enzyme anti-mold cleaning tablet and its preparation method. The preparation method of the cleaning tablet is the same as that shown in Embodiment 1, except that: In step S200, 10 wt% rhamnolipid and 5 wt% cross-linked polyvinylpyrrolidone are mixed evenly to form a primary layer powder, and the pressure parameters are: 5 kN for the primary layer, 5 kN for the intermediate layer, and 10 kN for the final layer.

[0053] Comparative Example 1 This comparative example provides a compound enzyme anti-mold cleaning tablet and its preparation method. This cleaning tablet does not employ a three-layer structure, and the preparation method is the same as shown in Example 1, except that: In step S200, after all the materials of the initial layer, intermediate layer and final layer in Example 1 are mixed evenly, they are pressed into single tablets in one go using a conventional tablet press with a pressure of 30kN.

[0054] Comparative Example 2 This comparative example provides a compound enzyme anti-mold cleaning tablet and its preparation method. The preparation method of this cleaning tablet is the same as that shown in Example 1, except that: Step S130 is omitted, i.e. there is no shell layer. Only calcium alginate gel microspheres are used, and the intermediate layer is prepared by using these shell-free microspheres to prepare the preform.

[0055] Comparative Example 3 This comparative example provides a compound enzyme anti-mold cleaning tablet and its preparation method. The preparation method of this cleaning tablet is the same as that shown in Example 1, except that: No sodium percarbonate particles were prepared; that is, in step S200, the final layer used sodium percarbonate particles that were not coated with citric acid.

[0056] Comparative Example 4 This comparative example provides a compound enzyme anti-mold cleaning tablet and its preparation method. The preparation method of this cleaning tablet is the same as that shown in Example 1, except that: In step S200, the pressure parameters are: 30kN for the initial layer, 30kN for the intermediate layer, and 50kN for the final layer.

[0057] Comparative Example 5 This comparative example provides a compound enzyme anti-mold cleaning tablet and its preparation method. The preparation method of this cleaning tablet is the same as that shown in Example 1, except that: In step S100, only chitinase powder is used, and the total enzyme loading remains unchanged at 3 wt%.

[0058] Comparative Example 6 This comparative example provides a compound enzyme anti-mold cleaning tablet and its preparation method. The cleaning tablet was purchased externally.

[0059] Test method: The cleaning tablets prepared in Examples 1-7 and Comparative Examples 1-6 were tested as follows. The test methods are as follows, and the test data are shown in Tables 1-3. Primary layer disintegration time test: the time required for the cleaning tablet to completely disintegrate and disperse in pure water at 25°C; Enzyme activity retention test after tableting: Immobilized enzyme microspheres before tableting and intermediate layer material separated from clean tablets after tableting were taken, lysed, and their enzyme activity was measured. The percentage of activity retention after tableting was calculated. Accelerated enzyme activity retention test after storage: The clean tablets were stored in a constant temperature and humidity chamber at 40℃ and 75% relative humidity for 28 days. After being taken out, the activity of the intermediate layer enzymes was measured, and the activity retention rate relative to the state before storage was calculated. Determination of effective oxygen retention rate after accelerated storage: The effective oxygen content of sodium percarbonate in the final layer of the cleaning tablet was determined by potassium permanganate titration. Effective oxygen retention rate after accelerated storage (%) = (effective oxygen content measured after 28 days of storage / effective oxygen content measured before storage) × 100%; Black stain bleaching rate test: Prepare a glass slide uniformly coated with a standard mold black stain simulant, immerse it in a cleaning solution for a certain period of time, use a colorimeter to measure the L* value of the glass slide before and after immersion, and calculate the bleaching rate; Detergency test: Using a standard artificially soiled cloth, test the detergency ratio of the cleaning tablet solution in water of specified hardness; Biofilm removal efficiency test: Standard mold biofilms were pre-cultured on the surface of a glass slide. After treatment with a cleaning solution, the amount of residual biofilm was determined by crystal violet staining, and the removal rate was calculated. Example 1 is as follows. Figure 2 As shown, Comparative Example 6 is as follows Figure 3 As shown; Hard surface mold removal test: The moldy area was cleaned with a cleaning tablet solution according to the standard procedure, and the mold removal effect was evaluated by visual scoring and colony count. Tablet hardness: The hardness of the clean tablets was measured using a tablet hardness tester; Table 1 ; pH value measurement: The cleaning tablet was placed in 200mL of pure water, and the pH value of the solution was continuously monitored at 0, 1, 5, 10 and 30min using a pH meter. The results are shown in Table 2. Table 2 ; Thickness measurement of each layer: The overall thickness of the entire piece was measured with a micrometer, and the average of the measurements was taken. The results are shown below. Table 3 ; As shown in Tables 1-3, this application is superior to the comparative example in all aspects of activity protection, storage stability, cleaning efficiency, and time-sequential release control. The enzyme activity retention rate of Comparative Example 1 was only 35% after tableting and only 15% after accelerated storage, proving that without physical isolation, tableting pressure and contact during storage directly damage the enzyme. The cleaning effect was far lower than that of Example 1, proving that the components interfered with each other due to premature mixing, failing to achieve a synergistic effect. Although Comparative Example 2 was better than Comparative Example 1 after tableting and accelerated storage, it was still far inferior to Example 1. The alginate gel core is effective, but the chitosan shell is also important for resisting the mechanical stress of tableting and the erosion of the storage environment. The effective oxygen content of Comparative Example 3 was only 68%, significantly lower than that of Example 1, demonstrating that without the acidic coating layer, sodium percarbonate had largely decomposed during tableting or storage. The pH of Comparative Example 3 rose to 8.0 within 5 minutes, while that of Example 1 took 10 minutes to reach 8.2, indicating that the coating layer effectively delayed the dissolution and release of sodium percarbonate, achieving delayed bleaching. The black stain bleaching rate and biofilm removal rate were lower than those of Example 1, suggesting that the premature release of the oxidant failed to synergize well with the enzymatic hydrolysis stage. Comparative Example 4 showed significantly lower results after tableting and storage compared to Example 1, indicating that applying less pressure to the fragile enzyme microsphere layer was a key process parameter for protecting its activity. The biofilm removal rate and detergency ratio of Comparative Example 5 were significantly lower than those of Example 1, which used a multi-enzyme system. Comparative Example 6 provided basic effectiveness in conventional detergency and short-term bleaching, but was significantly inferior to the examples in deep biofilm removal, synergistic sequential cleaning, and long-term shelf stability. Example 6 was significantly inferior to Example 1, which used a preform. Although Example 6 was still superior to most comparative examples, further preparing the immobilized enzyme microspheres into enzyme-loaded hydrogel preforms can provide additional mechanical buffering and activity protection, which is an effective means to further optimize product performance.

[0060] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application 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. Such 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 this application, and should all be included within the protection scope of this application.

Claims

1. A cleaning tablet, characterized in that, The cleaning tablet comprises a primary layer, a secondary layer, and a final layer, which are stacked sequentially. The primary layer includes a surfactant and a disintegrant; The intermediate layer comprises immobilized enzyme microspheres and washing aid components; The final layer includes an alkali source and sodium percarbonate particles coated with acidic substances. The immobilized enzyme microspheres include a core layer and a shell layer. The core layer includes an alginate gel and an enzyme embedded in the alginate gel. The shell layer includes chitosan.

2. The cleaning sheet according to claim 1, characterized in that, The acidic substance includes at least one of citric acid and citrate; and / or The alkali source includes at least one of sodium carbonate, sodium bicarbonate, and sodium silicate; and / or The washing aid component includes at least one of tetraacetylethylenediamine, sodium citrate, and sodium sulfate; and / or The surfactant includes at least one of rhamnolipids and alkyl polyglycosides; and / or The disintegrant includes at least one of croscarmellose sodium, croscarmellose, and croscarmellose starch.

3. The cleaning sheet according to claim 1, characterized in that, Based on the total weight of the sodium percarbonate particles, the coating mass of the acidic substance is 1-10 wt%.

4. The cleaning sheet according to claim 1, characterized in that, The immobilized enzyme microspheres have a particle size of 50-200 μm; and / or Based on the total dry weight of the immobilized enzyme microspheres, the enzyme loading is 0.3-5 wt%.

5. A method for preparing a cleaning sheet as described in any one of claims 1-4, characterized in that, Includes the following steps: S100: Prepare the immobilized enzyme microspheres; S200: The initial layer material including the surfactant and the disintegrant, the intermediate layer material including the immobilized enzyme microspheres and the washing aid components, and the final layer material including the alkali source and the sodium percarbonate particles are layered and compressed into tablets to obtain the cleaning tablet.

6. The method according to claim 5, characterized in that, Step S100 specifically includes the following steps: S110. Mix the enzyme with sodium alginate solution to obtain a mixture; S120. The mixture is added to a calcium ion solution for cross-linking and curing treatment to form enzyme-loaded calcium alginate gel microspheres. S130. The enzyme-loaded calcium alginate gel microspheres are contacted with chitosan solution to obtain the immobilized enzyme microspheres.

7. The method according to claim 6, characterized in that, The process also includes the following after step S130: S140. The immobilized enzyme microspheres are freeze-dried or vacuum-dried at a low temperature below 40°C.

8. The method according to claim 5, characterized in that, In step S200, the sodium percarbonate particles are obtained by fluidized bed spray coating, which includes spraying a solution containing acidic substances with a pH of 2.0-3.5 onto the surface of the sodium percarbonate particles.

9. The method according to claim 5, characterized in that, In step S200, the layered tableting is performed in an inert gas atmosphere, and the layered tableting uses a layered tableting mold to apply different tableting pressures to the initial layer, the intermediate layer and the final layer respectively. The pressure of the initial efficiency layer is 5-30 kN; The pressure of the intermediate-efficiency layer is 5-20kN; The pressure of the final layer is 10-50 kN.

10. The application of a cleaning sheet as described in any one of claims 1-4 in hard surface cleaning, characterized in that, The hard surface includes kitchen countertops, sanitary ware, tiles, or hard furniture surfaces.

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