A composite cat litter and a method of making the same

Abstract

The present application belongs to the technical field of pet products, and particularly relates to a composite cat litter and a preparation method thereof. The composite cat litter comprises an inner core layer and an organic coating continuously coated on the outer surface of the inner core layer, and the inner core layer is a soil powder or a soil powder ball sand. The present application adopts the inner core and the organic coating to jointly form the composite cat litter with a stable core-shell structure. The composite cat litter has a persistent and stable deodorizing effect and good wear resistance, and has a low cost, thereby solving the contradiction between performance and cost in the cat litter technology, and effectively overcoming the inherent defects of the pure mineral soil sand, such as weak deodorizing performance and large dust.

Description

Technical Field

[0001] This invention belongs to the field of pet product technology, specifically relating to a composite cat litter and its preparation method. Background Technology

[0002] In the current pet supplies market, cat litter, as a core essential product, has formed a pattern of multiple technological approaches coexisting, mainly including three categories: pure clay powder / clay wood powder ball litter, pure organic cat litter, and organic-clay mixed cat litter.

[0003] However, existing cat litter products all suffer from insurmountable technical flaws, resulting in limitations in user experience and overall performance:

[0004] Pure clay powder / wood powder ball litter cat litter lacks effective odor-absorbing components and has weak deodorizing ability. After pets excrete, odorous substances such as ammonia and hydrogen sulfide can easily spread quickly, affecting the indoor environment.

[0005] While pure organic cat litter solves the odor problem, the purchase price of organic raw materials is much higher than that of soil, resulting in high product costs. In addition, the higher density of organic materials makes the cat litter heavier overall, increasing the labor intensity when moving and replacing it.

[0006] Organic-soil mixed cat litter, due to its simple physical mixing method, does not form a stable structural system. This results in uneven distribution of organic materials in the soil and sand, causing localized deodorization effects that are either too strong or too weak, and poor performance consistency.

[0007] In summary, existing cat litter cannot achieve the synergistic advantages of low-cost earthen litter and high odor control from organic matter. All types of products are in a state of comprehensive coordination, making it difficult to meet consumers' high requirements for the overall performance of cat litter products. Therefore, there is an urgent need for a new type of cat litter that can integrate various advantages and avoid existing defects. Summary of the Invention

[0008] Based on the above technical background, the main objective of this invention is to provide a composite cat litter and its preparation method. This invention solves the long-standing contradiction between performance and cost in cat litter technology by using a stable core-shell structure with a soil-based core and an organic coating. It effectively solves the inherent defects of pure mineral soil litter, such as weak deodorization performance and high dust emission, while avoiding the problems of poor user experience and insufficient economy caused by the high cost of raw materials and the tendency of pure organic cat litter to gelatinize and stick to the bottom when exposed to water.

[0009] To achieve the aforementioned objectives, the technical solution adopted by this invention includes: The first aspect of the present invention is to provide a composite cat litter, the composite cat litter comprising a core and an organic coating, the organic coating being continuously and uniformly coated on the outer surface of the core, the core being composed of wood powder or wood powder ball litter.

[0010] The kernel has a particle size of 1–3.8 mm.

[0011] The soil powder is made from bentonite, silica sand and attapulgite, and the mass ratio of bentonite, silica sand and attapulgite is (2-5):(3-6):2.

[0012] Preferably, the mass ratio of bentonite, silica sand and attapulgite is 3:5:2.

[0013] The silt-filled sand is made from bentonite, soil and water, and the mass ratio of bentonite, soil and water is (0.05~0.08):1:(0.1~0.2).

[0014] Preferably, the clay granules are made from bentonite, soil and water, and the mass ratio of bentonite, soil and water is 0.06:1:0.15.

[0015] Preferably, the soil is made from the following raw materials in parts by weight: 50-80 parts by weight of bentonite, 60-90 parts by weight of silica sand, and 20-40 parts by weight of attapulgite.

[0016] More preferably, the soil is made from the following raw materials in parts by weight: 60 parts by weight of bentonite, 70 parts by weight of silica sand, and 30 parts by weight of attapulgite.

[0017] The thickness of the organic coating is 0.1–5 mm.

[0018] Experiments have shown that when the organic coating thickness is 0.1-0.5 mm, it can meet basic functional requirements and has the lowest cost, making it suitable for short-term or cost-sensitive scenarios. When the thickness of the organic coating is 0.5-3 mm, it can provide a long-lasting and stable deodorizing effect and good wear resistance while controlling costs, with an ammonia adsorption capacity of ≥90 mg / g, making it the best choice in terms of overall cost performance. When the organic coating thickness is 3-5 mm, the coating thickness design allows urine to be absorbed by the organic coating and slow down the penetration rate into the core when it comes into contact with the cat litter. This fully utilizes the deodorizing advantages of organic matter and provides sufficient reaction time for the core soil to absorb moisture and form high-strength clumps.

[0019] Preferably, the thickness of the organic coating is 0.5 to 3 mm.

[0020] More preferably, the thickness of the organic coating is 2 mm.

[0021] When the coating layer is designed to be 2 mm thick, it can provide a long-lasting and stable deodorizing effect and good wear resistance while controlling costs. The ammonia adsorption capacity is ≥90mg / g, making it the best choice in terms of overall cost performance.

[0022] The raw materials for preparing the organic coating include one or more of plant-based organic matter, animal-based organic matter, or microbial-based organic matter.

[0023] Preferably, the raw material for preparing the organic coating is plant-based organic matter, or the raw material for preparing the organic coating is a mixture of plant-based organic matter, animal-based organic matter, or microbial-based organic matter in a mass ratio of 1:1:1.

[0024] Preferably, the plant-based organic material is selected from one or more of cassava starch, cassava residue, corn starch, wheat bran, rice husk powder, peanut shell powder, and sugarcane bagasse, and the plant-based organic material has good film-forming properties or fibrous structure.

[0025] More preferably, the plant-based organic matter is cassava residue.

[0026] Preferably, the animal-based organic matter is selected from one or more of fish meal, bone meal, hydrolyzed collagen, and insect molting powder. Animal-based organic matter not only has adsorption properties but also provides nutrition.

[0027] More preferably, the animal-based organic matter is insect molting powder.

[0028] Preferably, the microbial-based organic matter is selected from one or more of fermented soybean residue, fermented mushroom residue, and mycelial powder. Microbial-based organic matter is mostly a product of waste resource utilization, which is environmentally friendly and has a well-developed porous structure.

[0029] More preferably, the microbial-based organic matter is fermented soybean residue.

[0030] The coating layer can be made by combining one or more types of organic compounds, which can flexibly optimize the overall performance of the coating layer.

[0031] The raw materials for preparing the organic coating also include an adhesive, which is added at an amount of 5-15% of the organic coating mass. The adhesive is used to enhance the cohesiveness of the coating layer itself and its adhesion to the core layer.

[0032] Preferably, the amount of adhesive added is 10% of the organic coating mass.

[0033] The adhesive comprises the following raw materials in parts by weight: 20-30 parts by weight of starch gum, 10-15 parts by weight of sodium carboxymethyl cellulose (CMC), 5-10 parts by weight of polyvinyl alcohol (PVA), 3-5 parts by weight of xanthan gum, and 3-5 parts by weight of guar gum.

[0034] Preferably, the adhesive comprises the following raw materials in parts by weight: 25 parts by weight of starch gum, 12 parts by weight of sodium carboxymethyl cellulose (CMC), 8 parts by weight of polyvinyl alcohol (PVA), 4 parts by weight of xanthan gum, and 4 parts by weight of guar gum.

[0035] A second aspect of the present invention is to provide a method for preparing the composite cat litter described in the first aspect of the present invention, the method comprising the following steps: After the raw materials for organic coating are made into a coating slurry, the coating method is used to coat the outer surface of the core to form a continuous coating layer. The wet granules after coating are dried and naturally cooled to obtain composite cat litter.

[0036] The steps described above are described in detail below.

[0037] The coating method includes one or two of the following: tumbling coating, spray coating, or fluidized bed coating.

[0038] Preferably, a continuous coating layer is first formed on the surface of the soil core using a tumbling method, so that the organic coating is in full contact with the soil core and forms a continuous coating layer. Then, a uniform organic coating layer is sprayed on the surface of the coating layer using a spray coating method.

[0039] When using the tumbling coating method, the tumbling speed should be controlled between 5 and 15 rpm.

[0040] Preferably, the rotation speed of the tumbling method needs to be controlled at 10 rpm.

[0041] When using the spray coating method, the inlet air temperature of the spray method needs to be controlled at 40-60℃.

[0042] Preferably, the inlet air temperature for the spray method is controlled at 50°C.

[0043] The drying conditions are as follows: drying in hot air at 40-80℃ for 1-3 hours, with real-time monitoring of particle moisture content until it drops to ≤5%.

[0044] Preferably, the drying conditions are: drying in hot air at 60°C for 2 hours, with real-time monitoring of the particle moisture content until it drops to ≤5%.

[0045] According to a preferred embodiment of the present invention, the method for preparing the coating slurry includes the following steps: One or more of plant-based organic matter, animal-based organic matter, or microbial-based organic matter are mixed with water, heated, and stirred to fully gelatinize the organic matter. Then, an adhesive is added and stirring is continued to obtain a coating slurry.

[0046] The steps described above are described in detail below.

[0047] Mix one or more of plant-based organic matter, animal-based organic matter, or microbial-based organic matter with water at a mass ratio of 1:(2-5). Preferably, one or more of plant-based organic matter, animal-based organic matter, or microbial-based organic matter are mixed with water at a mass ratio of 1:3.

[0048] Heat to 50–80°C and stir at 30–50 rpm for 10–20 minutes at that temperature.

[0049] Preferably, the temperature is raised to 70°C, and at this temperature, the mixture is stirred at 40 rpm for 15 min.

[0050] Add the binder, increase the stirring speed to 80-100 rpm, and continue stirring for 15-30 minutes to finally prepare a coating slurry with a uniform viscosity between 500-2000 mPa·s. During the preparation process, the binder is added after the organic materials have been fully gelatinized, and continuous stirring at 80-100 rpm for 15-30 minutes ensures its uniform dispersion in the coating slurry, guaranteeing consistent and strong adhesion throughout the formed coating layer.

[0051] Preferably, a binder is added, the stirring speed is increased to 90 rpm, and stirring is continued for 20 min to finally prepare a coating slurry with uniform viscosity between 1000 mPa·s.

[0052] During the preparation of the organic coating slurry, the slurry temperature is kept stable within the gelatinization temperature range of 50-80℃. The pre-prepared adhesive is slowly and evenly poured into the slurry under continuous low-to-medium speed stirring to prevent the adhesive from self-aggregating or clumping due to excessively high local concentration, thus ensuring that it can be initially dispersed in the gelatinized organic molecular network.

[0053] After the binder is initially added, the stirring speed is immediately increased and stabilized at 80-100 rpm, and stirring is continued at this speed for 15-30 minutes. The shear force field of the high stirring speed can effectively break up the existing small aggregates of binder, drive the binder molecules or colloidal particles to fully diffuse and migrate in the entire slurry system, achieve physical uniform mixing, and promote the pre-bonding of hydrogen bonds or van der Waals forces between the active groups of the binder and the gelatinized organic molecular chains, forming a preliminary stable and uniform composite colloidal system.

[0054] According to a preferred embodiment of the present invention, the method for preparing the civil engineering powder includes the following steps: Bentonite, silica sand, and attapulgite are mixed evenly, then pulverized at high speed. The pulverized product is sieved, and the undersize material is collected to obtain wood powder.

[0055] Preferably, bentonite, silica sand and attapulgite are mixed and stirred at a speed of 50-70 rpm for 20-30 minutes.

[0056] More preferably, bentonite, silica sand and attapulgite are mixed and stirred at 60 rpm for 25 min.

[0057] Preferably, after adding soil, the mixture is pulverized at a high speed of 3000-5000 rpm for 5-10 minutes.

[0058] More preferably, after adding soil, the mixture is pulverized at a high speed of 4000 rpm for 8 minutes.

[0059] The pulverized product is sieved through an 80-120 mesh vibrating screen, and the undersize material is collected as qualified civil engineering powder. The vibration frequency during sieving should be controlled at 20-30 Hz to ensure sieving efficiency.

[0060] Particles that fail to pass through the sieve must be returned to the crusher for re-crushing to ensure that the particle size uniformity of the resulting wood powder is ≤10%.

[0061] For wood powder, if the raw materials have a high moisture content during mixing, drying is also required.

[0062] The drying conditions are as follows: dry at 70-90℃ for 0.5-2 hours until the moisture content is ≤3%.

[0063] Preferably, the drying conditions are: drying at 80°C for 1 hour until the moisture content is ≤3%.

[0064] According to a preferred embodiment of the present invention, the method for preparing the silt-filled sand ball includes the following steps: Water and bentonite are added to the soil and stirred to form a homogeneous slurry. Then, the slurry is granulated, and the wet granules are dried and sieved to obtain soil powder ball sand.

[0065] Preferably, the granulation method is rolling granulation or spray granulation.

[0066] Preferably, the conditions for pelletizing are as follows: pelletizing is performed using a rolling pelletizer at 20–30 rpm for 15–30 min.

[0067] More preferably, the pelletizing conditions are: pelleting at 25 rpm for 20 min.

[0068] Preferably, the conditions for spray granulation are as follows: spray drying is performed using a spray drying tower, the solid content in the slurry needs to be adjusted to 30-40%, the inlet air temperature is 120-150℃, the outlet air temperature is 60-80℃, and the atomization pressure is 0.3-0.5MPa.

[0069] More preferably, the conditions for spray drying are: the solid content in the slurry needs to be adjusted to about 35%, the inlet air temperature is 130°C, the outlet air temperature is 70°C, and the atomization pressure is 0.4 MPa.

[0070] Preferably, the drying conditions are as follows: first, dry at 70-90℃ for 0.5-2 hours to remove surface moisture, then raise the temperature to 90-110℃ and dry for 1-3 hours until the moisture content is ≤3%.

[0071] More preferably, the drying conditions are as follows: drying is preferably carried out in a hot air drying equipment, first drying at 80°C for 1 hour, and then heating to 100°C for 2 hours to ensure that the moisture is completely evaporated and the moisture content is reduced to ≤3%.

[0072] The prepared soil silt ball sand has a microporous structure of 0.1-1 μm on its surface and an overall porosity of 15-25%. This microporous structure can enhance the mechanical interlocking with organic coatings, prevent coating from falling off, and improve the bonding force between soil silt ball sand and organic coatings.

[0073] After drying, the soil silt and sand are graded and screened, and particles with a diameter not in the range of 1 to 3.8 mm are strictly removed to obtain a core layer with qualified particle size and sufficient drying for later use.

[0074] The beneficial effects of this invention are as follows: (1) The composite cat litter of the present invention adopts a combination of soil core and organic coating to form a stable core-shell structure. It has the advantages of being lightweight, having a high deodorization rate, high clumping strength, low dust content, and low cost. It solves the long-standing contradiction between performance and cost in existing cat litter, effectively overcomes the inherent defects of pure mineral soil litter in terms of weak deodorization performance and high dust emission, and avoids the problems of poor user experience and insufficient economy caused by the high cost of raw materials and easy gelatinization and sticking to the bottom when exposed to water in pure organic cat litter.

[0075] (2) The raw materials for the organic coating of the composite cat litter cover a variety of sources such as plant-based, animal-based and microbial-based materials. The range of raw materials is wide, which not only reduces the dependence on a single expensive raw material, cassava starch, but also achieves diversification and low cost of raw materials. It can also utilize agricultural or food industry by-products to improve environmental benefits.

[0076] (3) The method of preparing the composite cat litter involves a simple physical mixing of organic matter and soil sand, so that the organic matter forms a continuous and uniform coating layer that completely covers the soil core. This eliminates the drastic performance fluctuations caused by uneven component distribution in the mixed cat litter, achieving a high degree of consistency in product performance and organically combining the advantages of low-cost core and high-performance coating.

[0077] (4) By precisely controlling the timing, amount, stirring speed and stirring time of the adhesive added in the preparation of the coating slurry, and by precisely limiting the particle size, porosity and drying process of the soil core, this invention ensures that a strong and uniform interface bond can be formed between the coating layer and the core, which greatly improves the structural stability and durability of the product. This makes the composite cat litter have excellent properties such as low dust, high agglomeration strength and high deodorization rate. Its agglomeration strength is ≥150N and the deodorization rate is ≥85%, and it can maintain the above excellent properties for a long time. Attached Figure Description

[0078] Figure 1 This diagram shows a molecular-level DR schematic of the organic coating of the composite cat litter described in this invention; Figure 2 An SEM electron microscope image of the core-shell structure in composite cat litter is shown. Detailed Implementation

[0079] The present invention will now be described in detail, and its features and advantages will become clearer and more apparent from these descriptions.

[0080] The core mechanism of the composite cat litter core-shell structure described in this invention lies in the construction of a molecular interface interaction system. In the core layer, a specific proportion of bentonite provides a large number of exchangeable cations and abundant silicon-oxygen tetrahedral / aluminum-oxygen octahedral layered structures at the molecular level. This endows the composite cat litter with strong ion exchange capacity and hydration expansion characteristics, which is the molecular basis for instant water absorption and the formation of stable agglomerates. Silica sand provides a rigid framework with its stable silicon-oxygen covalent bond network, while the nanorod-shaped crystal structure of attapulgite increases the specific surface area and adsorption sites. When these components are finely processed to form a uniform core, a large number of -OH and siloxane groups are exposed on its surface. During the coating process, the carboxymethyl group of CMC, the hydroxyl group of PVA, and the hydroxyl group of starch in the organic coating slurry are firmly bonded to these active groups through hydrogen bonds, coordination bonds, and even covalent bonds, forming a molecular cross-linking network at the interface. This establishes a strong molecular anchoring effect between the coating layer and the core, effectively preventing the coating from falling off during use. The role of organic coating lies in its molecular structure and function. Whether it is plant starch (amylose / amylose), protein, or polysaccharides produced by microbial fermentation, their macromolecular chains are rich in polar functional groups such as hydroxyl, amino, and carboxyl groups. These groups, through the bridging effect of adhesives, not only form a dense three-dimensional network with each other, but also firmly bind to the core through the aforementioned interfacial interactions. Secondly, these organic polymers themselves have the characteristics of being porous or capable of forming porous structures, such as the gelatinized gel network of starch, the pores of cellulose, and the honeycomb structure of fermentation products, creating a huge specific surface area and abundant nano / micron-sized pores at the molecular scale. When the main components of urine, such as urea, ammonia, and creatinine, come into contact with each other, the polar small molecules NH3 in the urine are efficiently adsorbed and captured on these pores and polar sites through van der Waals forces, hydrogen bonds, and even acid-base interactions, achieving rapid physicochemical deodorization. At the same time, the hydrophilic polymer network of the coating layer has capillary adsorption and swelling effects on water molecules, which can effectively slow down the permeation rate of liquid water into the core. This ensures that the organic layer has enough time to perform its adsorption and deodorization function, and also ensures that the bentonite in the core can fully exert its interlayer hydration and swelling effect at the most suitable water content, forming a dense and high-strength aggregate through ion-dipole interactions.

[0081] The preparation method of composite cat litter specifically includes the following steps: S11: Prepare raw materials according to the target core type. If preparing earth and wood powder, weigh bentonite, silica sand and attapulgite according to the mass ratio, put them into a mixer, mix and stir at 60-80 rpm for 20-30 minutes to obtain uniform earth and wood powder. Then put the uniform earth and wood powder into a high-speed pulverizer and pulverize at 3000-5000 rpm for 5-10 minutes. Then sieve the pulverized product through an 80-120 mesh vibrating screen, collect the undersize material as qualified earth and wood powder, and return the oversize material to the pulverizer for reprocessing. S12: For silt and sand, add 10-20% water and 5-8% bentonite slurry by mass to the soil as a binder, stir to form a uniform slurry, and then granulate it using a rolling pelletizer at 20-30 rpm for 15-30 min, or granulate it using a spray drying tower under the conditions of inlet air temperature of 120-150℃, outlet air temperature of 60-80℃, and atomization pressure of 0.3-0.5 MPa to obtain wet particles with a particle size of 1-3.8 mm; S13: Place the molded soil powder ball sand wet particles in a hot air drying equipment, first dry at 80℃ for 1 h, then raise the temperature to 100℃ and dry for 1-3 h, so that the moisture content is reduced to ≤3%. For soil powder, if the raw material has a high moisture content during mixing, it also needs to be dried. After drying, the soil powder ball sand is graded and screened, and particles with a particle size not in the range of 1-3.8 mm are strictly removed to obtain a qualified particle size and fully dried core layer for use. S14: Mix one or more of the selected plant-based, animal-based or microbial-based organic materials with water at a mass ratio of 1:2 to 1:5, place the mixture in a container equipped with heating and stirring functions, slowly heat it to 50 to 80°C, and continue stirring at this temperature for 10 to 20 minutes to fully gelatinize the organic materials. Then add 5 to 15% of the binder by mass of the organic materials, increase the stirring speed to 80 to 100 rpm, and continue stirring for 15 to 30 minutes to finally prepare a coating slurry with a uniform viscosity between 500 and 2000 mPa·s. S15: Using tumbling coating, spray coating, or fluidized bed coating, the resulting core particles are fully in contact with the prepared coating slurry to form a continuous coating layer. Specific process parameters need to be precisely controlled: tumbling rotation speed of 5-15 rpm, spray coating inlet air temperature of 40-60℃. The wet particles after coating should be immediately transferred to a drying device and dried in hot air at 40-80℃ for 1-3 hours, with real-time monitoring of particle moisture content until it drops to ≤5%. After drying, allow it to cool naturally to room temperature to obtain the composite cat litter product.

[0082] Specifically, in the preparation of civil engineering powder, the uniformity of mixing directly affects the stability of subsequent agglomeration performance. Sufficient stirring time and speed must be ensured. The combination of rotation speed and time in the crushing process aims to achieve efficient crushing while avoiding excessive crushing and generating too much ultrafine dust.

[0083] For the silt-sand granulation process, parameter control during granulation determines the sphericity, particle size distribution, and surface microporous structure of the particles. Real-time particle size monitoring and fine-tuning during rolling granulation are key to obtaining the particle size. Matching the slurry solids content and atomization parameters during spray granulation is a prerequisite for forming regular spherical particles. The segmented drying process first removes surface free water at low temperature and then appropriately raises the temperature to drive away internal bound water. This not only prevents surface cracking of the particles but also ensures thorough drying, strictly controlling the moisture content to no more than 3%, thus guaranteeing the storage stability of the core and the adhesion effect of subsequent coating slurry.

[0084] Specifically, in the slurry preparation stage, the ratio of organic materials to water can be finely adjusted within a given range according to the specific characteristics of the selected organic matter. It is necessary to ensure that the slurry has suitable fluidity and solid content. The heating and gelatinization process must be carried out with a steady temperature rise to avoid local overheating that could lead to denaturation of the organic matter or uneven gelatinization, which would affect the film quality. The timing of the addition of the adhesive and the high-speed stirring process are crucial to ensure that the adhesive molecules are uniformly dispersed in the slurry system and can form a uniform and firm bonding network inside the coating layer and at the interface with the core after drying. During the coating process, the selected tumbling, spraying, or fluidized bed methods all require precise control of equipment parameters. The tumbling speed and the interval between spraying / rolling determine the uniformity and thickness of the coating. The inlet air temperature and atomization pressure of the spray coating affect the atomization effect of the slurry and the initial drying speed of the wet particles, preventing adhesion. The final drying and curing step uses a relatively mild temperature of 40–80°C, which can slowly and evenly remove moisture from the coating layer, avoiding shrinkage and cracking or peeling from the core due to excessively rapid drying.

[0085] Example The present invention is further illustrated below with specific examples. These embodiments are merely illustrative and not intended to limit the scope of the invention. All raw materials used in the embodiments of the present invention are commercially available.

[0086] Example 1 The composite cat litter of this embodiment includes a core and an organic coating continuously covering the outer surface of the core layer, which together constitute a stable core-shell structure. The core is a clay powder, which is made by mixing bentonite, silica sand and attapulgite in a mass ratio of 3:5:2, and then crushing and passing it through a 100-mesh sieve. The organic coating is a uniform coating layer formed by plant-based organic matter with a thickness of 2 mm. An adhesive of 10% of the total mass is added to the organic coating to enhance the cohesion of the coating layer itself and its adhesion to the core layer.

[0087] The kernel layer, when made into civil engineering powder, includes: Weigh out bentonite, silica sand, and attapulgite in parts by weight, mix them according to the mixing ratio to form mixed soil powder, and pre-dry the mixed soil powder to a moisture content of ≤5%.

[0088] The material was crushed at 4000 rpm for 8 minutes and then classified through a 100-mesh vibrating screen. The vibration frequency was controlled at 25 Hz during the sieving process to ensure sieving efficiency. Particles that fail to pass through the sieve must be returned for re-crushing to ensure that the particle size uniformity of the resulting wood powder is ≤10%.

[0089] The organic coating is made from cassava residue, which has good film-forming properties and fibrous structure.

[0090] The thickness of the organic coating is designed as follows: When the thickness of the organic coating is 2 mm, it can provide a long-lasting and stable deodorizing effect and good wear resistance while controlling costs. The ammonia adsorption capacity is ≥90 mg / g, making it the best choice in terms of overall cost performance. The adhesive comprises the following raw materials in parts by weight: 25 parts starch glue, 12 parts sodium carboxymethyl cellulose (CMC), 8 parts polyvinyl alcohol (PVA), 4 parts xanthan gum, and 4 parts guar gum. During the preparation process, the adhesive is added after the organic materials have been fully gelatinized, and the mixture is continuously stirred at 90 rpm for 25 minutes to ensure that it is evenly dispersed in the coating slurry, thus ensuring that the formed coating layer has consistent and strong bonding properties throughout.

[0091] The binder is added after the organic material has been fully gelatinized, and the mixture is stirred continuously at 90 rpm for 25 minutes, including: During the preparation of the organic coating slurry, the slurry temperature is kept stable within the gelatinization temperature range of 60℃. The pre-prepared adhesive is slowly and evenly poured into the slurry under continuous medium-low speed stirring to avoid self-aggregation or agglomeration of the adhesive due to excessive local concentration, and to ensure that it can be initially dispersed in the gelatinized organic molecular network. After the binder is initially added, the stirring speed is immediately increased and stabilized at 90 rpm, and stirring is continued at this speed for 25 minutes. The shear force field of the high stirring speed can effectively break up the existing small aggregates of binder, drive the binder molecules or colloidal particles to fully diffuse and migrate in the entire slurry system, achieve physical uniform mixing, and promote the pre-bonding of hydrogen bonds or van der Waals forces between the active groups of the binder and the gelatinized organic molecular chains, forming a preliminary stable and uniform composite colloidal system.

[0092] The preparation method for the above-mentioned composite cat litter specifically includes the following steps: S11: Weigh bentonite, silica sand and attapulgite according to the above weight proportions, put the weighed raw materials into a mixer, mix and stir at 60 rpm for 25 minutes to obtain uniformly mixed soil powder, then put the uniformly mixed soil powder into a high-speed pulverizer, pulverize at 4000 rpm for 8 minutes, then sieve the pulverized product through a 100-mesh vibrating screen, collect the undersize material as qualified soil powder, and return the oversize material to the pulverizer for reprocessing; S12: For earth and wood powder, if the raw material has a high moisture content during mixing, it needs to be dried. The drying conditions are: dry at 80℃ for 1 hour until the moisture content is ≤3%. After drying, the earth and wood powder should be graded and screened to strictly remove particles with a particle size not in the range of 1 to 3.8 mm, so as to obtain earth and wood powder with qualified particle size and sufficient drying for use. S13: Mix the selected plant-based organic material (cassava residue) with water at a mass ratio of 1:4, place it in a container with heating and stirring functions, slowly heat it to 70°C, and continue stirring at this temperature for 15 min to fully gelatinize the organic material. Then add 10% of the binder by mass of the organic material, increase the stirring speed to 90 rpm, and continue stirring for 25 min to finally prepare a coating slurry with uniform viscosity between 1500 mPa·s. S14: The spray coating method is adopted to ensure that the core particles are in full contact with the prepared coating slurry and form a continuous coating layer. The specific process parameters need to be precisely controlled. The tumbling speed is 10 rpm and the inlet air temperature of the spray method is 50℃. The wet particles after coating should be immediately transferred to the drying equipment and dried in hot air at 60℃ for 2 hours. The moisture content of the particles should be monitored in real time until it drops to ≤5%. After drying, the particles should be naturally cooled to room temperature to obtain the composite cat litter product.

[0093] The segmented drying process used in this invention first removes surface free water at low temperature, and then appropriately raises the temperature to drive away internal bound water. This not only prevents cracking of the particle surface, but also ensures thorough drying, strictly controlling the moisture content to no more than 3%, thus guaranteeing the storage stability of the core and the adhesion effect of subsequent coating slurry.

[0094] During the coating process, the selected spraying method requires precise control of equipment parameters. The inlet air temperature and atomization pressure of the spray coating are related to the atomization effect of the slurry and the initial drying speed of the wet particles to prevent adhesion. The final drying and curing step uses a relatively mild temperature of 60°C to slowly and evenly remove moisture from the coating layer, avoiding shrinkage and cracking of the coating layer or peeling from the core due to excessive drying.

[0095] Example 2 The composite cat litter of this embodiment includes a core layer and an organic coating continuously covering the outer surface of the core layer, which together constitute a stable core-shell structure. The core layer is selected from granulated and dried soil silt particles with a particle size of 2 mm. The organic coating is a uniform coating layer formed by plant-based organic matter, animal-based organic matter, and microbial-based organic matter. The mixing ratio of plant-based organic matter, animal-based organic matter, and microbial-based organic matter is 1:1:1. The coating layer is 3 mm thick, and an adhesive accounting for 10% of its mass is added to the organic coating. The adhesive is used to enhance the cohesion of the coating layer itself and its adhesion to the core layer.

[0096] The soil-silk ball sand is prepared by mixing bentonite, soil and water in a mass ratio of 0.06:1:0.15.

[0097] The soil material is prepared by mixing the following raw materials in parts by weight: 60 parts by weight of bentonite, 70 parts by weight of silica sand, and 30 parts by weight of attapulgite.

[0098] When the core layer is silt and sand, the particle size is controlled within 5 mm, and the granulation process can be either rolling pelletizing or spray granulation. When rolling into balls, the granulator speed is controlled at 25 rpm and the granulation time is 25 min. The particle size is precisely controlled by real-time monitoring and adjustment of the water addition rate. During spray granulation, the solid content of the soil powder ball mortar needs to be adjusted to 35%, the atomizing nozzle pressure is 0.4 MPa, the inlet air temperature is 140℃, and the outlet air temperature is 70℃, in order to form spherical particles. The prepared silt-sand has a microporous structure of 0.5 μm on the surface and an overall porosity of 20%. Its DR schematic diagram is shown below. Figure 1 As shown, its SEM image is as follows Figure 2 As shown, this microporous structure can enhance the mechanical interlocking with organic coatings and prevent the coating from falling off. After granulation, the particles are dried in stages. First, they are dried at 80℃ for 1 hour to remove surface moisture, and then dried at 100℃ for 2 hours to ensure that the internal moisture is completely evaporated. The final moisture content is ≤3%. After drying, the particles are screened to remove unqualified particles to ensure a high degree of uniformity in the core particle size.

[0099] The raw materials for preparing organic coatings are plant-based, animal-based, and microbial-based organic compounds mixed in a mass ratio of 1:1:1. Among them, the plant-based organic matter is cassava residue, which has good film-forming properties or fibrous structure; Animal-based organic matter is insect excrement powder, which, in addition to its adsorption properties, may also provide nutrients. Microbial-based organic matter consists of fermented soybean residue, fermented mushroom residue, and mycelial powder, which are mostly products of waste resource utilization. They are environmentally friendly and have a well-developed porous structure. The organic coating thickness is designed to be 3mm: When the coating layer is 3-5mm thick, the thickness design allows urine to be absorbed by the organic coating when it comes into contact with the cat litter, thus slowing down the penetration rate into the core. This fully utilizes the deodorizing advantages of organic matter and provides sufficient reaction time for the core soil to absorb moisture and form high-strength clumps.

[0100] The adhesive comprises, by weight, 25 parts starch glue, 12 parts sodium carboxymethyl cellulose (CMC), 8 parts polyvinyl alcohol (PVA), 4 parts xanthan gum, and 4 parts guar gum. During the preparation process, the adhesive is added after the organic materials have been fully gelatinized, and the mixture is continuously stirred at 85 rpm for 25 minutes to ensure that it is evenly dispersed in the coating slurry, thus ensuring that the formed coating layer has consistent and strong bonding properties throughout.

[0101] The binder is added after the organic material has been fully gelatinized, and stirred continuously at 90 rpm for 25 minutes, including: During the preparation of the organic coating slurry, the slurry temperature is kept stable within the gelatinization temperature range of 60℃. The pre-prepared adhesive is slowly and evenly poured into the slurry under continuous medium-low speed stirring to avoid self-aggregation or agglomeration of the adhesive due to excessive local concentration, and to ensure that it can be initially dispersed in the gelatinized organic molecular network. After the binder is initially added, the stirring speed is immediately increased and stabilized at 90 rpm, and stirring is continued at this speed for 25 minutes. The shear force field of the high stirring speed can effectively break up the existing small aggregates of binder, drive the binder molecules or colloidal particles to fully diffuse and migrate in the entire slurry system, achieve physical uniform mixing, and also promote the pre-bonding of hydrogen bonds or van der Waals forces between the active groups of the binder and the gelatinized organic molecular chains, forming a preliminary stable and uniform composite colloidal system.

[0102] The preparation method of the above-mentioned composite cat litter specifically includes the following steps: S11: Mix bentonite, soil and water in a mass ratio of 0.06:1:0.15 to obtain soil powder ball mortar. Granulate the soil powder ball mortar in a spray drying tower under the conditions of inlet air temperature of 140℃, outlet air temperature of 70℃ and atomization pressure of 0.4MPa to obtain soil powder ball wet particles with a particle size of 5mm. S12: Place the molded soil powder ball wet particles in a hot air drying equipment, first dry at 80℃ for 1 h, then raise the temperature to 100℃ and dry for 2 h, so that the moisture content is reduced to ≤3%, and obtain core particles with qualified particle size and sufficient drying for later use. S13: Mix the selected plant-based, animal-based, or microbial-based organic material mixture (in which the mass ratio of plant-based, animal-based, or microbial-based organic materials is 1:1:1) with water at a mass ratio of 1:5, place it in a container with heating and stirring functions, slowly heat it to 80°C, and continue stirring at this temperature for 20 minutes to fully gelatinize the organic materials. Then add 15% of the binder by mass of the organic materials, increase the stirring speed to 100 rpm, and continue stirring for 30 minutes to finally prepare a coating slurry with uniform viscosity between 2000 mPa·s. S14: The core particles are fully contacted with the prepared coating slurry using a tumbling coating method to form a continuous coating layer. Specific process parameters require precise control: tumbling speed of 15 rpm and spray inlet air temperature of 60℃. The wet particles after coating should be immediately transferred to a drying device and dried under 80℃ hot air for 3 hours, with real-time monitoring of the particle moisture content until it drops to ≤5%. After drying, allow it to cool naturally to room temperature to obtain the finished composite cat litter with an organic coating. An SEM image of this composite cat litter is shown below. Figure 2 As shown, from Figure 2 As can be seen, the coating layer is uniformly coated on the surface of the core particles.

[0103] Comparative Example Comparative Example 1 Pure earth powder ball litter cat litter: Pure clay powder is made by mixing bentonite, silica sand, and attapulgite in a mass ratio of 3:5:2, then crushing and passing it through a 100-mesh sieve.

[0104] Its preparation method includes the following steps: Weigh out bentonite, silica sand and attapulgite according to the above weight proportions, put the weighed raw materials into a mixer, mix and stir at 60 rpm for 25 minutes to obtain uniformly mixed soil powder, then put the uniformly mixed soil powder into a high-speed pulverizer, pulverize at 4000 rpm for 8 minutes, then sieve the pulverized product through a 100-mesh vibrating screen, collect the undersize material as qualified soil powder, and return the oversize material to the pulverizer for reprocessing. The soil powder was dried at 80℃ for 1 hour until its moisture content was ≤3%. After drying, the soil powder spherical sand was graded and screened, and particles with a particle size not in the range of 1 to 3.8 mm were strictly removed to obtain pure soil powder spherical sand with qualified particle size and sufficient drying.

[0105] Comparative Example 2 The composite cat litter was prepared in a manner similar to that in Example 1, except that in step S14, the spray coating method was not used, and the obtained core particles were not brought into full contact with the prepared coating slurry to form a continuous coating layer. Instead, the wood powder and the coating slurry were simply physically mixed.

[0106] Experimental Example Experiment Example 1 Performance Test A comprehensive data analysis experiment was conducted to compare the above-mentioned Examples 1-2 and Comparative Example 1 with existing cat litters on the market. The testing standards and specific testing procedures for their deodorization rate, bulk density, cohesion strength, and dust content are as follows: (1) Deodorization rate (ammonia) test standard: Reference standard: QB / T4526-2013 "Pebbly Bentonite for Pet Bedding"; Test principle: Ammonia adsorption capacity determination: A quantitative cat litter sample is placed in a sealed container, a certain concentration of ammonia is injected, and the container is placed at 25°C for 24 hours. The concentration of residual ammonia in the container after adsorption is measured using a gas chromatograph or an ammonia detection tube, and the ammonia adsorption capacity per unit mass of cat litter (mg / g) is calculated.

[0107] Deodorization rate determination: Under the same conditions, the deodorization rate (%) is calculated by comparing the difference between the initial ammonia concentration and the concentration after adsorption.

[0108] (2) Bulk density test standard Reference standard: GB / T6286-1986 "Method for determination of bulk density of molecular sieves".

[0109] Test principle: The cat litter sample is dropped freely from a specified height into a graduated cylinder of known volume. After the surface is leveled, it is weighed, and the mass per unit volume is calculated.

[0110] Test steps: Take a sample of dry cat litter and mix it thoroughly under natural conditions. Slowly pour the sample into the 250mL graduated cylinder from a height of about 5cm from the mouth of the graduated cylinder until it is full; Use a ruler to smooth the surface, but do not compact it; Weigh the sample in the graduated cylinder, accurate to 0.1g; Calculate bulk density = sample mass / graduated cylinder volume (g / cm³) 3 ); Repeatability requirement: Perform two parallel measurements and take the arithmetic mean.

[0111] (3) Clumping strength test standard Reference standard: Refer to the method for determining agglomeration in QB / T4526-2013 "Pet pad granular bentonite".

[0112] Test principle: Simulate the effect of pet urine on cat litter, form aggregates, and use a compressive strength tester to determine the maximum force value when the aggregates break.

[0113] Test steps: Take a measured amount of cat litter (usually 100-200g) and spread it evenly in the test container; Use a pipette or syringe to add a quantitative amount of simulated urine (usually 10-15 mL, containing urea, NaCl, etc.) or saline solution to the surface of the cat litter. Let it stand for a certain period of time to allow it to clump together; Remove the aggregate and place it on a compressive strength tester (or weighing sensor); Apply pressure at a constant rate and record the maximum pressure value (unit: N) when the aggregate breaks.

[0114] (4) Dust content test standard Reference standard: Refer to the dust content determination method in QB / T4526-2013 "Pet pad granular bentonite".

[0115] Test principle: Cat litter is vibrated and sieved through a sieve with a specific aperture, and the mass percentage of fine powder passing through the sieve is measured.

[0116] Test steps: Take 500 g of dried cat litter sample; Place the sample on a sieve with the specified aperture. Cover the sieve and place it on the vibrating sieve machine, vibrating at a certain frequency of 30Hz for 5-10 minutes. Remove the sieve and weigh the powder that passed through it. Calculate dust content (%) = mass of powder passing through the sieve / total sample mass × 100%.

[0117] The test results and comparison results are shown in Table 1-2 below: Table 1: Comparison of the technical performance of this embodiment 1-2, comparative example 1-2 and existing technologies

[0118] Table 2: Comparison of performance indicators between core-shell structures and existing technologies

[0119] Table 3: Microscopic Comparison of Raw Material Composition and Structural Morphology

[0120] Table 4: Microscopic Comparison of Pore Structure and Adsorption Performance

[0121] Table 5: Microscopic Comparison of Interface Bonding and Mechanical Properties

[0122] As shown in Tables 1-5, the present invention makes a uniform core of soil-based material with a specific ratio, and uses an adhesive to help organic matter form a continuous, dense and controllable coating layer on the surface of the core. The core-shell structure is uniform and stable, and the dense coating layer completely isolates the dust escape channel from the physical level, thus achieving an extremely low dust amount.

[0123] See attached document Figure 1-2 The present invention is a composite cat litter with a core-shell structure. The coating layer on its surface is rich in micron / nano-scale pores, which can be used to lock in odor molecules such as ammonia. The pores of the core and the bentonite layer can quickly absorb moisture and expand and clump together, so that the soil-based core and the organic coating can work together to achieve efficient deodorization and rapid strong clumping. In contrast, the mixed cat litter (Comparative Example 2) has mixed pores, and the pure cassava litter has poor cohesion, is muddy, has low strength, is easy to stick to the bottom, and has poor deodorization.

[0124] The composite cat litter of this invention uses multi-level interfacial bonding (mechanical interlocking, hydrogen bonding, coordination bonding) to firmly combine the soil core and organic coating into an organic whole, giving it excellent properties such as high adsorption, high deodorization rate, high strength clumping and lightweight, and solving the inherent defects of traditional cat litter such as poor deodorization rate, poor liquid absorption, poor strength and easy gelatinization.

[0125] The present invention has been described in detail above with reference to specific embodiments and exemplary examples; however, these descriptions should not be construed as limiting the present invention. Those skilled in the art will understand that various equivalent substitutions, modifications, or improvements can be made to the technical solutions and embodiments of the present invention without departing from the spirit and scope of the invention, and all such modifications and improvements fall within the scope of the present invention. The scope of protection of the present invention is defined by the appended claims.

Claims

1. A composite cat litter, characterized in that, The composite cat litter includes a core and an organic coating, wherein the organic coating covers the outer surface of the core, and the core is composed of wood powder or wood powder ball litter. The kernel has a particle size of 1–3.8 mm; The thickness of the organic coating is 0.1–5 mm.

2. The composite cat litter according to claim 1, characterized in that, The soil powder is made from bentonite, silica sand and attapulgite, and the mass ratio of bentonite, silica sand and attapulgite is (2-5):(3-6):

2.

3. The composite cat litter according to claim 1, characterized in that, The silt-filled sand is made from bentonite, soil and water, and the mass ratio of bentonite, soil and water is (0.05~0.08):1:(0.1~0.2).

4. The composite cat litter according to claim 3, characterized in that, The soil material is made from the following raw materials in parts by weight: 50-80 parts by weight of bentonite, 60-90 parts by weight of silica sand, and 20-40 parts by weight of attapulgite.

5. The composite cat litter according to claim 1, characterized in that, The raw materials for preparing the organic coating include one or more of plant-based organic matter, animal-based organic matter, or microbial-based organic matter; The plant-based organic material is selected from one or more of the following: cassava starch, cassava residue, corn starch, wheat bran, rice husk powder, peanut shell powder, and sugarcane bagasse, and / or... The animal-based organic compound is selected from one or more of fish meal, bone meal, hydrolyzed collagen, and insect molting powder; and / or, The microbial-based organic matter is selected from one or more of fermented soybean residue, fermented bacterial residue, and mycelial powder.

6. The composite cat litter according to claim 5, characterized in that, The raw materials for preparing the organic coating also include an adhesive, wherein the amount of adhesive added is 5-15% of the mass of the organic coating; The adhesive comprises the following raw materials in parts by weight: 20-30 parts by weight of starch gum, 10-15 parts by weight of sodium carboxymethyl cellulose, 5-10 parts by weight of polyvinyl alcohol, 3-5 parts by weight of xanthan gum, and 3-5 parts by weight of guar gum.

7. A method for preparing the composite cat litter according to any one of claims 1 to 6, characterized in that, The preparation method includes the following steps: After the raw materials for organic coating are made into a coating slurry, the coating method is used to coat the outer surface of the core to form a continuous coating layer. The wet granules after coating are dried and naturally cooled to obtain composite cat litter. The core is a granular material made from raw materials of earth and wood powder or earth and sand. The coating method includes one or two of the following: tumbling coating, spray coating, or fluidized bed coating.

8. The preparation method according to claim 7, characterized in that, The preparation method of the coating slurry includes the following steps: Mix one or more of plant-based organic matter, animal-based organic matter, or microbial-based organic matter with water, heat to 50-80°C, stir at 30-50 rpm for 10-20 minutes at this temperature, then add the binder, increase the stirring speed to 80-100 rpm, and continue stirring for 15-30 minutes to obtain the coating slurry.

9. The preparation method according to claim 7, characterized in that, The method for preparing the civil engineering powder includes the following steps: Bentonite, silica sand, and attapulgite are mixed and stirred at 50–70 rpm for 20–30 min, then pulverized at high speed. The pulverized product is sieved, and the undersize material is collected to obtain wood powder.

10. The preparation method according to claim 7, characterized in that, The method for preparing the silt-filled sand ball includes the following steps: Water and bentonite are added to the soil and stirred to form a homogeneous slurry. Then the slurry is granulated, the wet particles are dried and sieved to obtain soil powder ball sand. The granulation method is either rolling granulation or spray granulation; The conditions for the rolling pelletizing process are as follows: pelletizing is performed using a rolling pelletizing machine at 20–30 rpm for 15–30 min; The conditions for spray granulation are as follows: spray drying is carried out using a spray drying tower, with an inlet air temperature of 120-150℃, an outlet air temperature of 60-80℃, and an atomization pressure of 0.3-0.5 MPa.

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