A slow-release defoaming agent and a preparation method thereof

Abstract

The application discloses a slow-release defoaming agent and a preparation method and application thereof, and belongs to the technical field of daily chemical auxiliaries. The preparation method is as follows: mixing silicon grease, silicon polyether and polyacrylic acid to obtain active substance A, mixing the active substance A with an inner-layer high-melting-point hydrophobic ester slow-release matrix B to obtain a mixture E, loading the mixture E on a carrier C, and then sending the loaded product into a fluidized bed and performing spray coating and drying of an outer-layer low-melting-point hydrophobic coating material D, wherein the temperature of the fluidized bed is not lower than the melting point of the outer-layer material, and the temperature of the fluidized bed is lower than the melting point of the outer-layer material, so as to obtain the slow-release defoaming agent. The defoaming agent is formed with a double-layer wrapping and a double slow-release structure by the outer-layer low-melting-point hydrophobic coating material and the inner-layer high-melting-point hydrophobic ester slow-release matrix, can gradually release active defoaming components in the washing process, realizes sustained defoaming, and improves the mixing uniformity and storage stability of a powder system.

Description

Technical Field

[0001] This invention relates to the field of daily chemical additives and defoaming materials, and particularly to a slow-release defoamer with a double-layer encapsulation and double slow-release structure and its preparation method, and its application in laundry detergent, liquid detergent and other washing systems. Background Technology

[0002] Defoamers are widely used in detergents, textiles, papermaking, fermentation, water treatment, and chemical processing to suppress or eliminate foam in systems. For laundry products such as laundry powder and liquid detergent, excessive foam can affect rinsing efficiency, reduce the operational stability of washing machinery, and may negatively impact the consumer experience. Therefore, defoamers are typically added to control foam.

[0003] Most existing defoamers are added to detergent systems in liquid or ordinary solid granule form. Liquid defoamers are prone to uneven dispersion, adsorption loss, migration and agglomeration in powder systems; while ordinary solid defoamers are easy to add to laundry detergent systems, they usually have defects such as a single release path, too rapid release in the early stage, failure to defoam in the later stage, or insufficient release at low temperatures during actual washing, making it difficult to achieve both initial defoaming and continuous foam suppression.

[0004] Invention patent CN103298534A discloses the preparation of an O / W emulsion-type defoamer using higher alcohols, microcrystalline waxes, and polyols. This defoamer forms an oil-phase dispersion system through emulsification and utilizes polyols to inhibit oil-phase aggregation. To address the aforementioned issues, existing technologies have attempted to encapsulate the defoaming active ingredient using a single wax or ester material. However, single-layer encapsulation materials often only provide single-stage release control. When the melting point of the encapsulation material is low, the product is prone to softening and clumping during storage and transportation; when the melting point is high, the defoaming active ingredient is not easily released in a timely manner during washing. Especially during the use of laundry detergent, the washing liquid temperature, mechanical shear strength, and dissolution environment continuously change, making it difficult for a single-layer encapsulation structure to provide a stable and continuous defoaming effect at different stages.

[0005] Therefore, there is an urgent need to provide a sustained-release defoamer and its preparation method that can form a double-layer encapsulation structure, achieve dual sustained-release, and have the advantages of powder mixing uniformity, storage stability and continuous defoaming performance. Summary of the Invention

[0006] Purpose of the invention

[0007] The purpose of this invention is to overcome the shortcomings of existing solid defoamers, such as a single release pathway, insufficient defoaming persistence, and poor storage stability, and to provide a slow-release defoamer and its preparation method. This defoamer forms an inner slow-release phase through an inner high-melting-point hydrophobic ester slow-release matrix and an outer coating phase through an outer low-melting-point hydrophobic coating material. This allows the active defoaming components to be released in stages during washing due to temperature changes, mechanical shearing, and the gradual softening of the coating layer, thereby achieving continuous control of foam height.

[0008] Technical solution

[0009] To achieve the above objectives, the present invention provides the following technical solution:

[0010] A sustained-release defoamer comprises an active ingredient A, an inner high-melting-point hydrophobic ester-based sustained-release matrix B, a carrier C, and an outer low-melting-point hydrophobic coating material D; wherein, the active ingredient A is prepared by mixing silicone grease, silicone polyether, and polyacrylic acid; the inner high-melting-point hydrophobic ester-based sustained-release matrix B is used to mix with the active ingredient A to form an inner sustained-release mixture E containing the active ingredient; the carrier C is used to load the mixture E; and the outer low-melting-point hydrophobic coating material D is used to form an outer coating structure on the particles after the mixture E is loaded on the carrier C.

[0011] The outer low-melting-point hydrophobic coating material D has a melting point of 30–50°C, preferably 34–46°C. The inner high-melting-point hydrophobic ester-based sustained-release matrix B has a melting point 5–20°C higher than that of the outer low-melting-point hydrophobic coating material D, preferably 8–15°C higher. This melting point difference allows the outer low-melting-point hydrophobic coating material D to soften, crack, or partially melt during the initial washing stage or at lower temperatures. Then, the inner high-melting-point hydrophobic ester-based sustained-release matrix B further controls the release of active ingredient A under higher temperatures or continuous shear, thus forming a hierarchical release structure from the outside in, achieving double-layer encapsulation and dual sustained release.

[0012] Preferably, the outer low-melting-point hydrophobic coating material D is selected from one or a combination of at least two of low-melting-point paraffin wax, low-melting-point microcrystalline wax, low-melting-point Fischer-Tropsch wax blends, and low-melting-point polyethylene wax blends. The low-melting-point Fischer-Tropsch wax blends and low-melting-point polyethylene wax blends refer to hydrophobic coating materials whose overall melting point is within the range of 30–50°C after compounding or blending.

[0013] The inner high-melting-point hydrophobic ester-based sustained-release matrix B is used to mix with the active ingredient A to form mixture E, and after being loaded onto the carrier C, it is located between the active ingredient A and the outer low-melting-point hydrophobic coating material D, thereby forming the inner sustained-release phase. The inner high-melting-point hydrophobic ester-based sustained-release matrix B is solid or semi-solid at room temperature, and can encapsulate, fix, and sustain the release of the active ingredient A. During the washing process, as the temperature rises and the mechanical shearing effect increases, the inner high-melting-point hydrophobic ester-based sustained-release matrix B gradually softens, swells, ruptures, or partially melts, allowing the active ingredient A to be gradually released from the inner sustained-release phase.

[0014] Preferably, the inner high-melting-point hydrophobic ester-based slow-release matrix B has a melting point of 40–70°C, more preferably 45–65°C. When the outer low-melting-point hydrophobic coating material D has a melting point of 30–50°C, the inner high-melting-point hydrophobic ester-based slow-release matrix B can be matched and selected according to the melting point of the outer material, so that a melting point difference of 5–20°C is formed between the two.

[0015] Preferably, the HLB value of the inner high-melting-point hydrophobic ester-based slow-release matrix B is 1 to 12, more preferably 2 to 8. When the HLB value is too high, the inner slow-release matrix is ​​prone to disperse or dissolve too quickly in the washing water system, which is not conducive to continuous slow release; when the HLB value is low, it is beneficial to improve its encapsulation stability of silicon-based active materials and hydrophobic slow-release effect.

[0016] Preferably, the inner high-melting-point hydrophobic ester-based sustained-release matrix has melt flowability suitable for mixing with active ingredient A at 60–90°C, and its melt viscosity is such that it can achieve uniform mixing, spraying, kneading, or loading. More preferably, the inner high-melting-point hydrophobic ester-based sustained-release matrix can encapsulate or disperse active ingredient A in a molten or softened state, and forms a stable inner sustained-release phase after cooling.

[0017] Preferably,

[0018] The inner high-melting-point hydrophobic ester slow-release matrix is ​​a fatty acid ester component that is solid or waxy at room temperature, has a melting point of 40-70℃, and an HLB value of 1-12.

[0019] Preferably, the fatty acid ester component is selected from one or a combination of at least two of the following: glyceryl monostearate, glyceryl distearate, glyceryl palmitate stearate, sorbitan monostearate, sorbitan tripearate, sorbitan monopalmitate, ethylene glycol stearate, ethylene glycol distearate, low-HLB polyglycerol long-chain fatty acid esters, low-HLB fatty acid sucrose esters, low-HLB fatty acid polyethylene glycol esters, hydrogenated vegetable oil, and hydrogenated vegetable oil glycerides.

[0020] More preferably, the low-HLB polyglycerol long-chain fatty acid ester is polyglycerol stearate, polyglycerol distearate, polyglycerol palmitate, or a combination thereof with an HLB value of 1 to 12.

[0021] The low HLB fatty acid sucrose ester is a sucrose difatty acid ester, a sucrose polyfatty acid ester, or a combination thereof with an HLB value of 1 to 12.

[0022] The low HLB fatty acid polyethylene glycol ester is polyethylene glycol stearate, polyethylene glycol distearate, polyethylene glycol palmitate, or a combination thereof with an HLB value of 1 to 12.

[0023] The carrier C is a solid carrier used to load the mixture E, and is selected from one or a combination of at least two of starch, inorganic salts, and inorganic porous materials. Preferably, the inorganic salt is one or more of sodium sulfate, sodium carbonate, and silicates; and the inorganic porous material is one or more of silica, diatomaceous earth, zeolite, and kaolin.

[0024] The amount of active ingredient A is 10-30% of the total mass of the defoamer; wherein, based on the total mass of active ingredient A, silicone grease, silicone polyether and polyacrylic acid are 50-60%, 2-5% and 35-45% respectively, and the total of the three is 100%; the polyacrylic acid is based on the effective ingredients.

[0025] The amount of the inner high-melting-point hydrophobic ester-based slow-release matrix B is 5-20% of the total mass of the defoamer;

[0026] The carrier C is used in an amount that accounts for 50-65% of the total mass of the defoamer;

[0027] The amount of the outer low-melting-point hydrophobic coating material D is 3-10% of the total mass of the defoamer;

[0028] The present invention also provides a method for preparing the above-mentioned sustained-release defoamer, comprising the following steps:

[0029] Step 1: Add silicone grease, silicone polyether and polyacrylic acid to a container, raise the temperature to 40-50℃, stir evenly to obtain active ingredient A;

[0030] Step 2: Add the inner high-melting-point hydrophobic ester sustained-release matrix B to the active ingredient A, and stir and mix evenly at a temperature 10-20°C higher than the melting point of the inner high-melting-point hydrophobic ester sustained-release matrix B to obtain mixture E.

[0031] Step 3: Contact mixture E with carrier C, so that carrier C loads mixture E;

[0032] Step 4: The loaded product is fed into a fluidized bed, and molten low-melting-point hydrophobic coating material or a spray containing the outer low-melting-point hydrophobic coating material is sprayed into the fluidized bed, so that the outer low-melting-point hydrophobic coating material coats the surface of the carrier C loaded with mixture E; the temperature of the fluidized bed is controlled to be no lower than the melting point of the outer low-melting-point hydrophobic coating material, and the temperature of the fluidized bed is controlled to be lower than the melting point of the outer low-melting-point hydrophobic coating material. After spray drying and cooling curing, a slow-release defoamer is obtained.

[0033] Preferably, the inner high-melting-point hydrophobic ester sustained-release matrix described in step two is preheated to a molten or softened state before being mixed with active ingredient A, so as to improve the dispersion uniformity of active ingredient A in the inner sustained-release phase.

[0034] Preferably, in step three, the mixture E is loaded onto the surface and / or pores of the carrier C by means of stirring, spraying, kneading and granulation, drum mixing or continuous mixing.

[0035] Preferably, in step four, the temperature of the material entering the fluidized bed is within the range of the melting point of the outer low-melting-point hydrophobic coating material to 15°C above the melting point, and the temperature of the material exiting the fluidized bed is within the range of 1 to 15°C below the melting point of the outer low-melting-point hydrophobic coating material. This temperature control helps the outer low-melting-point hydrophobic coating material to have good spray flowability and film-forming properties when entering the fluidized bed, and to complete cooling and solidification when leaving the fluidized bed, thereby forming a stable outer coating structure.

[0036] Preferably, step four further includes a crushing and / or sieving step to obtain defoamer particles within the target particle size range.

[0037] This invention also provides the application of the above-mentioned slow-release defoamer in laundry detergent. After the defoamer is added to the laundry detergent, during the washing process, the outer low-melting-point hydrophobic coating material gradually softens or breaks down with the increase of temperature and mechanical shearing. Subsequently, the inner high-melting-point hydrophobic ester slow-release matrix further controls the release of active ingredient A, thereby forming a double-layer encapsulation and double slow-release process, achieving continuous inhibition and elimination of foam.

[0038] Beneficial effects

[0039] 1. Clear double-layer encapsulation structure: The present invention uses an inner high-melting-point hydrophobic ester-based sustained-release matrix as the inner sustained-release phase, an outer low-melting-point hydrophobic coating material as the outer coating phase, and a carrier C as the load skeleton, thus forming a multiphase composite particle of "active substance A-inner sustained-release matrix-carrier C-outer coating material" in terms of structure.

[0040] 2. Excellent dual-layer sustained-release effect: The outer layer of low-melting-point hydrophobic coating material has a melting point of 30-50℃, while the inner layer of high-melting-point hydrophobic ester-based sustained-release matrix has a melting point 5-20℃ higher than that of the outer layer of low-melting-point hydrophobic coating material. This allows the outer coating phase and the inner sustained-release phase to form a staged softening and segmented release during the washing process, which is beneficial for both initial defoaming and subsequent foam suppression.

[0041] 3. Good storage stability: The low-melting-point hydrophobic coating material on the outer layer can fix and isolate particles loaded with mixture E under normal temperature conditions, reducing the migration, exudation and agglomeration of active substances.

[0042] 4. Strong process adaptability: By controlling the inlet fluidized bed temperature to be no lower than the melting point of the outer low-melting-point hydrophobic coating material and the outlet fluidized bed temperature to be lower than the melting point of the outer low-melting-point hydrophobic coating material, both the spray coating film-forming effect of the outer material and the cooling and solidification effect during discharge can be taken into account.

[0043] 5. High industrial feasibility: The present invention can produce the target product by mixing, loading, fluidized bed spray coating and drying and curing. The process has good continuity and is suitable for the industrial production of powder washing products such as laundry detergent. Detailed Implementation

[0044] The present invention will be further described below with reference to embodiments and comparative examples. The following embodiments are used to illustrate the technical solutions of the present invention and the technical effects they can achieve, and are not intended to limit the scope of protection of the present invention. Any equivalent substitutions or conventional adjustments to material types, proportions, or process parameters made under the technical concept of the present invention should be understood as falling within the scope of protection of the present invention.

[0045] Unless otherwise stated, all percentages in the following examples and comparative examples are by mass percentages, and are based on a total mass of 100% for the slow-release defoamer product; the proportion of components within active ingredient A is based on the total mass of active ingredient A, and the total of silicone grease, silicone polyether, and polyacrylic acid is 100%. Polyacrylic acid is calculated based on the effective ingredient. The melting point is the principal melting temperature or softening melting temperature of the corresponding material, which can be confirmed by differential scanning calorimetry, capillary method, or supplier technical data; the HLB value is the nominal value, measured value, or weighted value calculated according to the compounding ratio of the corresponding trade name.

[0046] In the following embodiments, the silicone grease may be a silicone paste mainly composed of polydimethylsiloxane and hydrophobic silica; the silicone polyether may be a polyether-modified polysiloxane; and the polyacrylic acid may be a detergent-compatible polyacrylic acid or its salt dispersant. All of the above raw materials may be conventional industrial products in the art, as long as they meet the requirements for forming active ingredient A, the inner layer sustained-release mixture E, the carrier-loaded structure, and the outer layer coating structure.

[0047] Example 1

[0048] A method for preparing a sustained-release defoamer includes the following steps:

[0049] (1) Weigh 13.20% silicone grease, 1.20% silicone polyether, and 9.60% polyacrylic acid based on the total mass of the slow-release defoamer, add them to a mixing device, heat to 45°C, and stir for 30 min at 300 r / min to obtain active ingredient A. The active ingredient A accounts for 24.00% of the total mass of the slow-release defoamer; based on the total mass of active ingredient A, the mass ratio of silicone grease, silicone polyether, and polyacrylic acid is 55.0%: 5.0%: 40.0%.

[0050] (2) The inner high-melting-point hydrophobic ester sustained-release matrix B is selected from 14.00% glyceryl monostearate, which has a melting point of 58°C and an HLB value of 3.8. The inner high-melting-point hydrophobic ester sustained-release matrix B is heated to 70°C to form a molten or softened state and then added to the active ingredient A. The mixture is stirred for 40 minutes at 65-70°C to make the active ingredient A uniformly dispersed and embedded by the inner high-melting-point hydrophobic ester sustained-release matrix B, thus obtaining the inner sustained-release mixture E containing the active ingredient.

[0051] (3) The mixture E is sprayed into 54.00% of the carrier C at 60-65°C. The carrier C is composed of 37.80% sodium sulfate and 16.20% starch (mass ratio 7:3). After stirring, mixing and cooling, the carrier C loads the mixture E.

[0052] (4) The outer low-melting-point hydrophobic coating material D is selected from 8.00% low-melting-point refined paraffin wax with a melting point of 42℃. The loaded material is fed into a fluidized bed, and the molten outer low-melting-point hydrophobic coating material D is sprayed into the fluidized bed; the temperature of the fluidized bed is controlled at 48℃ and the temperature of the fluidized bed is controlled at 36℃. After spray coating, drying, cooling and solidification and sieving, slow-release defoamer particles with a particle size of 0.30~1.20mm are obtained.

[0053] Example 2

[0054] A method for preparing a sustained-release defoamer includes the following steps:

[0055] (1) Weigh 10.40% silicone grease, 0.60% silicone polyether, and 9.00% polyacrylic acid based on the total mass of the slow-release defoamer, add them to a mixing device, heat to 45°C, and stir for 30 min at 300 r / min to obtain active ingredient A. The active ingredient A accounts for 20.00% of the total mass of the slow-release defoamer; based on the total mass of active ingredient A, the mass ratio of silicone grease, silicone polyether, and polyacrylic acid is 52.0%:3.0%:45.0%.

[0056] (2) The inner high-melting-point hydrophobic ester sustained-release matrix B is selected from 15.00% sorbitan monostearate, which has a melting point of 54℃ and an HLB value of 4.7. The inner high-melting-point hydrophobic ester sustained-release matrix B is heated to 66℃ to form a molten or softened state and then added to the active ingredient A. The mixture is stirred for 40 min at 60-66℃ to make the active ingredient A uniformly dispersed and embedded by the inner high-melting-point hydrophobic ester sustained-release matrix B, thus obtaining the inner sustained-release mixture E containing the active ingredient.

[0057] (3) The mixture E is sprayed into 57.00% of the carrier C at 60-65°C. The carrier C is composed of 45.60% sodium carbonate and 11.40% diatomaceous earth (mass ratio 8:2). After stirring, mixing and cooling, the carrier C loads the mixture E.

[0058] (4) The outer low-melting-point hydrophobic coating material D is a compound of 8.00% low-melting-point microcrystalline wax and low-melting-point refined paraffin wax, with a melting point of 40℃. The loaded material is fed into a fluidized bed, and molten outer low-melting-point hydrophobic coating material D is sprayed into the fluidized bed; the inlet temperature of the fluidized bed is controlled at 46℃, and the outlet temperature of the fluidized bed is controlled at 34℃. After spray coating, drying, cooling and solidification and sieving, slow-release defoamer particles with a particle size of 0.30~1.20mm are obtained.

[0059] Example 3

[0060] A method for preparing a sustained-release defoamer includes the following steps:

[0061] (1) Based on the total mass of the slow-release defoamer, weigh 16.80% silicone grease, 1.12% silicone polyether, and 10.08% polyacrylic acid, add them to a mixing device, heat to 45°C, and stir for 30 minutes at 300 r / min to obtain active ingredient A. The active ingredient A accounts for 28.00% of the total mass of the slow-release defoamer; based on the total mass of active ingredient A, the mass ratio of silicone grease, silicone polyether, and polyacrylic acid is 60.0%: 4.0%: 36.0%.

[0062] (2) The inner high-melting-point hydrophobic ester sustained-release matrix B is selected from 10.00% ethylene glycol distearate, which has a melting point of 62℃ and an HLB value of 5.5. The inner high-melting-point hydrophobic ester sustained-release matrix B is heated to 75℃ to form a molten or softened state and then added to the active ingredient A. The mixture is stirred for 35 minutes at 70-75℃ to make the active ingredient A uniformly dispersed and embedded by the inner high-melting-point hydrophobic ester sustained-release matrix B, thus obtaining the inner sustained-release mixture E containing the active ingredient.

[0063] (3) The mixture E is sprayed into 55.00% of the carrier C at 60-65°C. The carrier C is composed of 11.00% silica, 27.50% zeolite and 16.50% starch (mass ratio 2:5:3). After stirring, mixing and cooling, the carrier C loads the mixture E.

[0064] (4) The outer low-melting-point hydrophobic coating material D is a mixture of 7.00% low-melting-point microcrystalline wax and low-melting-point Fischer-Tropsch wax, with a melting point of 46℃. The loaded material is fed into a fluidized bed, and molten outer low-melting-point hydrophobic coating material D is sprayed into the fluidized bed; the inlet temperature of the fluidized bed is controlled at 52℃, and the outlet temperature of the fluidized bed is controlled at 40℃. After spray coating, drying, cooling and solidification, and sieving, slow-release defoamer particles with a particle size of 0.30~1.20mm are obtained.

[0065] Example 4

[0066] A method for preparing a sustained-release defoamer includes the following steps:

[0067] (1) Weigh 10.44% silicone grease, 0.36% silicone polyether, and 7.20% polyacrylic acid based on the total mass of the slow-release defoamer, add them to a mixing device, heat to 45°C, and stir for 30 min at 300 r / min to obtain active ingredient A. The active ingredient A accounts for 18.00% of the total mass of the slow-release defoamer; based on the total mass of active ingredient A, the mass ratio of silicone grease, silicone polyether, and polyacrylic acid is 58.0%: 2.0%: 40.0%.

[0068] (2) The inner high-melting-point hydrophobic ester sustained-release matrix B is a compound of 18.00% glyceryl monostearate and sorbitan monopalmitate, wherein glyceryl monostearate accounts for 10.80% and sorbitan monopalmitate accounts for 7.20%, with a mass ratio of 6:4. Its melting point is 55°C and its HLB value is approximately 4.9. The inner high-melting-point hydrophobic ester sustained-release matrix B is heated to 68°C to form a molten or softened state and then added to the active ingredient A. The mixture is stirred for 40 minutes at 63-68°C to ensure that the active ingredient A is uniformly dispersed and embedded by the inner high-melting-point hydrophobic ester sustained-release matrix B, thereby obtaining the inner sustained-release mixture E containing the active ingredient.

[0069] (3) The mixture E is sprayed into 59.00% of the carrier C at 60-65°C. The carrier C is composed of 35.40% sodium sulfate, 11.80% sodium silicate and 11.80% starch (mass ratio 6:2:2). After stirring, mixing and cooling, the carrier C loads the mixture E.

[0070] (4) The outer low-melting-point hydrophobic coating material D is selected from 5.00% low-melting-point polyethylene wax mixture with a melting point of 45℃. The loaded material is fed into a fluidized bed, and the molten outer low-melting-point hydrophobic coating material D is sprayed into the fluidized bed; the inlet temperature of the fluidized bed is controlled at 51℃, and the outlet temperature of the fluidized bed is controlled at 39℃. After spray coating, drying, cooling and curing and sieving, slow-release defoamer particles with a particle size of 0.30~1.20mm are obtained.

[0071] Example 5

[0072] A method for preparing a sustained-release defoamer includes the following steps:

[0073] (1) Weigh 6.60% silicone grease, 0.60% silicone polyether, and 4.80% polyacrylic acid based on the total mass of the slow-release defoamer, add them to a mixing device, heat to 45°C, and stir for 30 min at 300 r / min to obtain active ingredient A. The active ingredient A accounts for 12.00% of the total mass of the slow-release defoamer; based on the total mass of active ingredient A, the mass ratio of silicone grease, silicone polyether, and polyacrylic acid is 55.0%: 5.0%: 40.0%.

[0074] (2) The inner high-melting-point hydrophobic ester sustained-release matrix B is a compound of 20.00% polyethylene glycol distearate and polyglycerol distearate, wherein polyethylene glycol distearate accounts for 14.00% and polyglycerol distearate accounts for 6.00%, with a mass ratio of 7:3. Its melting point is 57°C and its HLB value is approximately 7.5. The inner high-melting-point hydrophobic ester sustained-release matrix B is heated to 70°C to form a molten or softened state and then added to the active ingredient A. The mixture is stirred for 40 minutes at 65-70°C to ensure that the active ingredient A is uniformly dispersed and embedded by the inner high-melting-point hydrophobic ester sustained-release matrix B, thereby obtaining an inner sustained-release mixture E containing the active ingredient.

[0075] (3) The mixture E is sprayed into 65.00% of the carrier C at 60-65°C. The carrier C is composed of 32.50% sodium carbonate, 19.50% zeolite and 13.00% starch (mass ratio 5:3:2). After stirring, mixing and cooling, the carrier C loads the mixture E.

[0076] (4) The outer low-melting-point hydrophobic coating material D is a compound of 3.00% low-melting-point Fischer-Tropsch wax and low-melting-point refined paraffin wax, with a melting point of 44℃. The loaded material is fed into a fluidized bed, and molten outer low-melting-point hydrophobic coating material D is sprayed into the fluidized bed; the inlet temperature of the fluidized bed is controlled at 50℃, and the outlet temperature of the fluidized bed is controlled at 38℃. After spray coating, drying, cooling and solidification and sieving, slow-release defoamer particles with a particle size of 0.30~1.20mm are obtained.

[0077] Comparative Example 1

[0078] A method for preparing a sustained-release defoamer includes the following steps:

[0079] (1) Weigh 13.20% silicone grease, 1.20% silicone polyether, and 9.60% polyacrylic acid based on the total mass of the slow-release defoamer, add them to a mixing device, heat to 45°C, and stir for 30 min at 300 r / min to obtain active ingredient A. The active ingredient A accounts for 24.00% of the total mass of the slow-release defoamer; based on the total mass of active ingredient A, the mass ratio of silicone grease, silicone polyether, and polyacrylic acid is 55.0%: 5.0%: 40.0%.

[0080] (2) The inner high-melting-point hydrophobic ester sustained-release matrix B is selected from 14.00% glyceryl monostearate, which has a melting point of 58°C and an HLB value of 3.8. The inner high-melting-point hydrophobic ester sustained-release matrix B is heated to 70°C to form a molten or softened state and then added to the active ingredient A. The mixture is stirred for 40 minutes at 65-70°C to make the active ingredient A uniformly dispersed and embedded by the inner high-melting-point hydrophobic ester sustained-release matrix B, thus obtaining the inner sustained-release mixture E containing the active ingredient.

[0081] (3) The mixture E is sprayed into 54.00% of the carrier C at 60-65°C. The carrier C is composed of 43.4% sodium sulfate and 18.6% starch (mass ratio 7:3). After stirring, mixing and cooling, the carrier C loads the mixture E. After sieving, slow-release defoamer particles with a particle size of 0.30-1.20 mm are obtained.

[0082] Comparative Example 2

[0083] A method for preparing a sustained-release defoamer includes the following steps:

[0084] (1) Weigh 13.20% silicone grease, 1.20% silicone polyether, and 9.60% polyacrylic acid based on the total mass of the slow-release defoamer, add them to a mixing device, heat to 45°C, and stir for 30 min at 300 r / min to obtain active ingredient A. The active ingredient A accounts for 24.00% of the total mass of the slow-release defoamer; based on the total mass of active ingredient A, the mass ratio of silicone grease, silicone polyether, and polyacrylic acid is 55.0%: 5.0%: 40.0%.

[0085] (2) The inner high-melting-point hydrophobic ester sustained-release matrix B is selected from a low-melting-point fatty acid ester compound containing 14.00% of the compound, with a melting point of 38°C and an HLB value of 4.0. The inner high-melting-point hydrophobic ester sustained-release matrix B is heated to 70°C to form a molten or softened state and then added to the active ingredient A. The mixture is stirred for 40 minutes at 65-70°C to ensure that the active ingredient A is uniformly dispersed and embedded by the inner high-melting-point hydrophobic ester sustained-release matrix B, thereby obtaining an inner sustained-release mixture E containing the active ingredient.

[0086] (3) The mixture E is sprayed into 54.00% of the carrier C at 60-65°C. The carrier C is composed of 37.80% sodium sulfate and 16.20% starch (mass ratio 7:3). After stirring, mixing and cooling, the carrier C loads the mixture E.

[0087] (4) The outer low-melting-point hydrophobic coating material D is selected from 8.00% low-melting-point refined paraffin wax with a melting point of 42℃. The loaded material is fed into a fluidized bed, and the molten outer low-melting-point hydrophobic coating material D is sprayed into the fluidized bed; the temperature of the fluidized bed is controlled at 48℃ and the temperature of the fluidized bed is controlled at 36℃. After spray coating, drying, cooling and solidification and sieving, slow-release defoamer particles with a particle size of 0.30~1.20mm are obtained.

[0088] Comparative Example 3

[0089] A method for preparing a sustained-release defoamer includes the following steps:

[0090] (1) Based on the total mass of the slow-release defoamer, weigh 16.80% silicone grease, 1.12% silicone polyether, and 10.08% polyacrylic acid, add them to a mixing device, heat to 45°C, and stir for 30 minutes at 300 r / min to obtain active ingredient A. The active ingredient A accounts for 28.00% of the total mass of the slow-release defoamer; based on the total mass of active ingredient A, the mass ratio of silicone grease, silicone polyether, and polyacrylic acid is 60.0%: 4.0%: 36.0%.

[0091] (2) The inner high-melting-point hydrophobic ester sustained-release matrix B is selected from 10.00% ethylene glycol distearate, which has a melting point of 62℃ and an HLB value of 5.5. The inner high-melting-point hydrophobic ester sustained-release matrix B is heated to 75℃ to form a molten or softened state and then added to the active ingredient A. The mixture is stirred for 35 minutes at 70-75℃ to make the active ingredient A uniformly dispersed and embedded by the inner high-melting-point hydrophobic ester sustained-release matrix B, thus obtaining the inner sustained-release mixture E containing the active ingredient.

[0092] (3) The mixture E is sprayed into 55.00% of the carrier C at 60-65°C. The carrier C is composed of 11.00% silica, 27.50% zeolite and 16.50% starch (mass ratio 2:5:3). After stirring, mixing and cooling, the carrier C loads the mixture E.

[0093] (4) The outer low-melting-point hydrophobic coating material D is a mixture of 7.00% microcrystalline wax and Fischer-Tropsch wax with a melting point of 55°C. The loaded material is fed into a fluidized bed, and the molten outer low-melting-point hydrophobic coating material D is sprayed into the fluidized bed. The inlet temperature of the fluidized bed is controlled at 52°C and the outlet temperature of the fluidized bed is controlled at 40°C. After spray coating, drying, cooling and solidification and sieving, slow-release defoamer particles with a particle size of 0.30 to 1.20 mm are obtained.

[0094] Comparative Example 4

[0095] A method for preparing a sustained-release defoamer includes the following steps:

[0096] (1) Weigh 13.20% silicone grease, 1.20% silicone polyether, and 9.60% polyacrylic acid based on the total mass of the slow-release defoamer, add them to a mixing device, heat to 45°C, and stir for 30 min at 300 r / min to obtain active ingredient A. The active ingredient A accounts for 24.00% of the total mass of the slow-release defoamer; based on the total mass of active ingredient A, the mass ratio of silicone grease, silicone polyether, and polyacrylic acid is 55.0%: 5.0%: 40.0%.

[0097] (2) The inner high-melting-point hydrophobic ester sustained-release matrix B is selected from 14.00% glyceryl monostearate, which has a melting point of 58°C and an HLB value of 3.8. The inner high-melting-point hydrophobic ester sustained-release matrix B is heated to 70°C to form a molten or softened state and then added to the active ingredient A. The mixture is stirred for 40 minutes at 65-70°C to make the active ingredient A uniformly dispersed and embedded by the inner high-melting-point hydrophobic ester sustained-release matrix B, thus obtaining the inner sustained-release mixture E containing the active ingredient.

[0098] (3) The mixture E is sprayed into 54.00% of the carrier C at 60-65°C. The carrier C is composed of 37.80% sodium sulfate and 16.20% starch (mass ratio 7:3). After stirring, mixing and cooling, the carrier C loads the mixture E.

[0099] (4) The outer low-melting-point hydrophobic coating material D is selected from 8.00% low-melting-point refined paraffin wax with a melting point of 42℃. The loaded material is fed into a fluidized bed, and molten outer low-melting-point hydrophobic coating material D is sprayed into the fluidized bed; the inlet temperature of the fluidized bed is controlled at 48℃, and the outlet temperature of the fluidized bed is controlled at 46℃. After spray coating, drying, cooling and solidification and sieving, slow-release defoamer particles with a particle size of 0.30~1.20mm are obtained.

[0100] Comparative Example 5

[0101] A method for preparing a sustained-release defoamer includes the following steps:

[0102] (1) Weigh 13.20% silicone grease, 1.20% silicone polyether, and 9.60% polyacrylic acid based on the total mass of the slow-release defoamer, add them to a mixing device, heat to 45°C, and stir for 30 min at 300 r / min to obtain active ingredient A. The active ingredient A accounts for 24.00% of the total mass of the slow-release defoamer; based on the total mass of active ingredient A, the mass ratio of silicone grease, silicone polyether, and polyacrylic acid is 55.0%: 5.0%: 40.0%.

[0103] (2) The inner high-melting-point hydrophobic ester sustained-release matrix B is selected from 14.00% of polyethylene glycol stearate hydrophilic ester material, with a melting point of 47℃ and an HLB value of 18.8. The inner high-melting-point hydrophobic ester sustained-release matrix B is heated to 70℃ to form a molten or softened state and then added to the active ingredient A. The mixture is stirred for 40 minutes at 65-70℃ to make the active ingredient A uniformly dispersed and embedded by the inner high-melting-point hydrophobic ester sustained-release matrix B, thus obtaining the inner sustained-release mixture E containing the active ingredient.

[0104] (3) The mixture E is sprayed into 54.00% of the carrier C at 60-65°C. The carrier C is composed of 37.80% sodium sulfate and 16.20% starch (mass ratio 7:3). After stirring, mixing and cooling, the carrier C loads the mixture E.

[0105] (4) The outer low-melting-point hydrophobic coating material D is selected from 8.00% low-melting-point refined paraffin wax with a melting point of 42℃. The loaded material is fed into a fluidized bed, and the molten outer low-melting-point hydrophobic coating material D is sprayed into the fluidized bed; the temperature of the fluidized bed is controlled at 48℃ and the temperature of the fluidized bed is controlled at 36℃. After spray coating, drying, cooling and solidification and sieving, slow-release defoamer particles with a particle size of 0.30~1.20mm are obtained.

[0106] Comparative Example 6

[0107] A method for preparing a sustained-release defoamer includes the following steps:

[0108] (1) Weigh 13.20% silicone grease, 1.20% silicone polyether, and 9.60% polyacrylic acid based on the total mass of the slow-release defoamer, add them to a mixing device, heat to 45°C, and stir for 30 min at 300 r / min to obtain active ingredient A. The active ingredient A accounts for 24.00% of the total mass of the slow-release defoamer; based on the total mass of active ingredient A, the mass ratio of silicone grease, silicone polyether, and polyacrylic acid is 55.0%: 5.0%: 40.0%.

[0109] (2) The inner high-melting-point hydrophobic ester sustained-release matrix B is selected from 14.00% glyceryl monostearate, which has a melting point of 58°C and an HLB value of 3.8. The inner high-melting-point hydrophobic ester sustained-release matrix B is heated to 70°C to form a molten or softened state and then added to the active ingredient A. The mixture is stirred for 40 minutes at 65-70°C to make the active ingredient A uniformly dispersed and embedded by the inner high-melting-point hydrophobic ester sustained-release matrix B, thus obtaining the inner sustained-release mixture E containing the active ingredient.

[0110] (3) The mixture E is sprayed into 61.00% of the carrier C at 60-65°C. The carrier C is composed of 42.7% sodium sulfate and 18.3% starch (mass ratio 7:3). After stirring, mixing and cooling, the carrier C loads the mixture E.

[0111] (4) The outer low-melting-point hydrophobic coating material D is selected from 1.00% low-melting-point refined paraffin wax with a melting point of 42℃. The loaded material is fed into a fluidized bed, and the molten outer low-melting-point hydrophobic coating material D is sprayed into the fluidized bed; the temperature of the fluidized bed is controlled at 48℃ and the temperature of the fluidized bed is controlled at 36℃. After spray coating, drying, cooling and solidification and sieving, slow-release defoamer particles with a particle size of 0.30~1.20mm are obtained.

[0112] Comparative Example 7

[0113] This comparative example is basically the same as Example 1, except that the amount of the outer low-melting-point hydrophobic coating material D is increased to 12.00%, and the carrier C is adjusted to 50.00%; the remaining active ingredient A is 24.00%, and the inner high-melting-point hydrophobic ester slow-release matrix B is 14.00%. Because the amount of the outer coating material D is higher than the 3-10% specified in this invention, the coating layer is too thick, and the release of active ingredients is suppressed in the initial stage of washing.

[0114] A method for preparing a sustained-release defoamer includes the following steps:

[0115] (1) Weigh 13.20% silicone grease, 1.20% silicone polyether, and 9.60% polyacrylic acid based on the total mass of the slow-release defoamer, add them to a mixing device, heat to 45°C, and stir for 30 min at 300 r / min to obtain active ingredient A. The active ingredient A accounts for 24.00% of the total mass of the slow-release defoamer; based on the total mass of active ingredient A, the mass ratio of silicone grease, silicone polyether, and polyacrylic acid is 55.0%: 5.0%: 40.0%.

[0116] (2) The inner high-melting-point hydrophobic ester sustained-release matrix B is selected from 14.00% glyceryl monostearate, which has a melting point of 58°C and an HLB value of 3.8. The inner high-melting-point hydrophobic ester sustained-release matrix B is heated to 70°C to form a molten or softened state and then added to the active ingredient A. The mixture is stirred for 40 minutes at 65-70°C to make the active ingredient A uniformly dispersed and embedded by the inner high-melting-point hydrophobic ester sustained-release matrix B, thus obtaining the inner sustained-release mixture E containing the active ingredient.

[0117] (3) The mixture E is sprayed into 50.00% of the carrier C at 60-65°C. The carrier C is composed of 35% sodium sulfate and 15% starch (mass ratio 7:3). After stirring, mixing and cooling, the carrier C loads the mixture E.

[0118] (4) The outer low-melting-point hydrophobic coating material D is selected from 12.00% low-melting-point refined paraffin wax with a melting point of 42℃. The loaded material is fed into a fluidized bed, and the molten outer low-melting-point hydrophobic coating material D is sprayed into the fluidized bed; the inlet temperature of the fluidized bed is controlled at 48℃, and the outlet temperature of the fluidized bed is controlled at 36℃. After spray coating, drying, cooling and solidification and sieving, slow-release defoamer particles with a particle size of 0.30~1.20mm are obtained.

[0119] Performance Evaluation

[0120] The defoamers prepared in Examples 1-5 and Comparative Examples 1-7 were added to the same basic laundry detergent formula at an addition amount of 0.5 wt%, mixed evenly, and then foam control was evaluated. The blank sample was basic laundry detergent without added defoamer.

[0121] The evaluation method was as follows: 5.0 g of laundry detergent containing defoamer was added to 1000 mL of hard water with a hardness of 250 mg / L (calculated as CaCO3). A washing simulation was conducted under mechanical stirring conditions: the initial water temperature was 25℃, which was then increased to 60℃ within 10 minutes and maintained for 30 minutes, with a stirring speed of 400 r / min. The foam height was recorded at 0 min, 10 min, 20 min, and 30 min. Lower foam height with less change over time indicated better sustained defoaming performance.

[0122] The storage stability evaluation method was as follows: A sealed sample of laundry detergent containing defoamer was placed at 45°C for 30 days, and the presence of obvious clumping, adhesion, or leakage of active ingredients was observed. The results are shown in the table below.

[0123] sample 0min foam height / mm 10min foam height / mm 20min foam height / mm 30min foam height / mm 60℃ for 30 days blank sample 158 172 185 190 Continuous high foam Example 1 82 48 36 34 No obvious lumps, no exudation Example 2 86 52 39 36 No obvious lumps, no exudation Example 3 90 56 42 39 No obvious lumps, no exudation Example 4 84 50 37 35 No obvious lumps, no exudation Example 5 88 54 41 38 No obvious lumps, no exudation Comparative Example 1 76 92 128 146 slight oozing Comparative Example 2 72 88 110 126 Slight caking Comparative Example 3 126 118 104 96 No obvious clumping, insufficient initial release Comparative Example 4 84 66 72 90 Obvious adhesion and lumps Comparative Example 5 78 90 118 134 slight oozing Comparative Example 6 80 86 116 138 Slight exudation, localized caking Comparative Example 7 122 110 88 70 No obvious clumping, insufficient initial release

[0124] As shown in the table above, Examples 1-5 all use an inner high-melting-point hydrophobic ester-based sustained-release matrix B with a melting point of 40-70℃ and an HLB value of 1-12, and an outer low-melting-point hydrophobic coating material D with a melting point of 30-50℃. The melting point of the inner layer material is 5-20℃ higher than that of the outer layer material. The amounts of active ingredient A, inner sustained-release matrix B, carrier C, and outer coating material D in each example are in the ranges of 10-30%, 5-20%, 50-65%, and 3-10%, respectively. Therefore, they exhibit good continuous defoaming effect and storage stability during the washing process.

[0125] In Comparative Example 1, the outer coating structure was not formed, the release of active ingredient A was not adequately controlled, and the foam height increased significantly in the later stages. In Comparative Example 2, the melting point of the inner layer material was not higher than that of the outer layer material by 5–20°C, so effective staged release could not be achieved. In Comparative Example 3, the melting point of the outer layer material was too high, resulting in insufficient release at common washing temperatures and poor initial defoaming effect. In Comparative Example 4, the temperature exiting the fluidized bed was higher than the melting point of the outer layer material, leading to insufficient solidification of the coating layer and an increased risk of powder adhesion and agglomeration. In Comparative Example 5, the HLB value of the inner layer material was too high, resulting in excessively rapid release in the initial washing stage and a decrease in sustained defoaming performance in the later stages. In Comparative Example 6, the amount of outer coating material D was too low, the outer coating was discontinuous, and leakage or local agglomeration was likely to occur during storage. In Comparative Example 7, the amount of outer coating material D was too high, the coating layer was too thick, and the release of active ingredient A was insufficient in the initial washing stage.

[0126] The above examples and comparative examples illustrate that the mass percentages of active ingredient A, inner high-melting-point hydrophobic ester sustained-release matrix B, carrier C, and outer low-melting-point hydrophobic coating material D, the melting point and HLB value of the inner high-melting-point hydrophobic ester sustained-release matrix B, the melting point of the outer low-melting-point hydrophobic coating material D, the difference in melting points between the inner and outer layers, and the fluidized bed discharge curing temperature all collectively affect the sustained-release defoaming performance and storage stability of the defoamer.

Claims

1. A slow-release defoamer, characterized in that, The sustained-release defoamer is a particle having an inner sustained-release phase and an outer coating phase, comprising an active ingredient A, an inner high-melting-point hydrophobic ester sustained-release matrix B, a carrier C, and an outer low-melting-point hydrophobic coating material D; wherein, the active ingredient A is prepared by mixing silicone grease, silicone polyether, and polyacrylic acid, and the active ingredient A is mixed with the inner high-melting-point hydrophobic ester sustained-release matrix B to form an inner sustained-release mixture E containing the active ingredient, the inner sustained-release mixture E is loaded on the carrier C, and the outer low-melting-point hydrophobic coating material D coats the outer surface of the carrier C particles loaded with the inner sustained-release mixture E; based on the total mass of the finished sustained-release defoamer, the active ingredient A accounts for 10-30%, the inner high-melting-point hydrophobic ester sustained-release matrix B, ... The active ingredient A, the inner high-melting-point hydrophobic ester sustained-release matrix B, the carrier C, and the outer low-melting-point hydrophobic coating material D are all present in a total mass percentage of 5-20%, 50-65%, and 3-10%, respectively. The total mass percentage of the active ingredient A, the inner high-melting-point hydrophobic ester sustained-release matrix B, the carrier C, and the outer low-melting-point hydrophobic coating material D is 100%. The outer low-melting-point hydrophobic coating material D has a melting point of 30-50°C. The inner high-melting-point hydrophobic ester sustained-release matrix B has a melting point of 40-70°C and an HLB value of 1-12. The melting point of the inner high-melting-point hydrophobic ester sustained-release matrix B is 5-20°C higher than that of the outer low-melting-point hydrophobic coating material D.

2. The sustained-release defoamer according to claim 1, characterized in that, Based on the total mass of active ingredient A, the silicone grease is 50-60%, the silicone polyether is 2-5%, and the polyacrylic acid is 35-45%, and the total mass percentage of the silicone grease, silicone polyether, and polyacrylic acid is 100%; the polyacrylic acid is calculated based on the effective ingredient.

3. The sustained-release defoamer according to claim 1, characterized in that, The outer low-melting-point hydrophobic coating material D has a melting point of 34–46°C; the inner high-melting-point hydrophobic ester-based slow-release matrix B has a melting point of 45–65°C and an HLB value of 2–8, and the melting point of the inner high-melting-point hydrophobic ester-based slow-release matrix B is 8–15°C higher than the melting point of the outer low-melting-point hydrophobic coating material D.

4. The sustained-release defoamer according to claim 1, characterized in that, The inner high-melting-point hydrophobic ester slow-release matrix B is a fatty acid ester component that is solid or waxy at room temperature, has a melting point of 40-70℃, and an HLB value of 1-12. The fatty acid ester component is selected from one or a combination of at least two of the following: glyceryl monostearate, glyceryl distearate, glyceryl palmitate stearate, sorbitan monostearate, sorbitan tristearate, sorbitan monopalmitate, ethylene glycol stearate, ethylene glycol distearate, low-HLB polyglycerol long-chain fatty acid esters, low-HLB fatty acid sucrose esters, low-HLB fatty acid polyethylene glycol esters, hydrogenated vegetable oil, and hydrogenated vegetable oil glycerides.

5. The sustained-release defoamer according to claim 4, characterized in that, The low-HLB polyglycerol long-chain fatty acid ester is polyglycerol stearate, polyglycerol distearate, polyglycerol palmitate, or a combination thereof with an HLB value of 1 to 12; the low-HLB fatty acid sucrose ester is sucrose difatty acid ester, sucrose polyfatty acid ester, or a combination thereof with an HLB value of 1 to 12; the low-HLB fatty acid polyethylene glycol ester is polyethylene glycol stearate, polyethylene glycol distearate, polyethylene glycol palmitate, or a combination thereof with an HLB value of 1 to 12.

6. The sustained-release defoamer according to claim 1, characterized in that, The outer low-melting-point hydrophobic coating material D is selected from one or a combination of at least two of the following: low-melting-point paraffin wax, low-melting-point microcrystalline wax, low-melting-point Fischer-Tropsch wax blend, and low-melting-point polyethylene wax blend; the low-melting-point Fischer-Tropsch wax blend and the low-melting-point polyethylene wax blend are hydrophobic coating materials whose overall melting point is in the range of 30 to 50°C after compounding or blending.

7. The sustained-release defoamer according to claim 1, characterized in that, The carrier C is selected from one or a combination of at least two of starch, inorganic salts and inorganic porous materials; the inorganic salt is selected from one or more of sodium sulfate, sodium carbonate and silicates; the inorganic porous material is selected from one or more of silica, diatomaceous earth, zeolite and kaolin.

8. The sustained-release defoamer according to claim 1, characterized in that, The silicone grease is a silicone paste mainly composed of polydimethylsiloxane and hydrophobic silica, the silicone polyether is a polyether-modified polysiloxane, and the polyacrylic acid is polyacrylic acid or its salt dispersant.

9. The sustained-release defoamer according to claim 1, characterized in that, The particle size of the slow-release defoamer particles is 0.30–1.20 mm.

10. A method for preparing a sustained-release defoamer according to any one of claims 1 to 9, characterized in that, Includes the following steps: (1) Add silicone grease, silicone polyether and polyacrylic acid to a container, raise the temperature to 40-50°C, stir evenly to obtain active ingredient A; (2) Add the inner high-melting-point hydrophobic ester sustained-release matrix B to the active ingredient A, and stir and mix it evenly under the condition that the melting point of the inner high-melting-point hydrophobic ester sustained-release matrix B is 10-20°C higher than that of the inner high-melting-point hydrophobic ester sustained-release matrix B to obtain the inner sustained-release mixture E containing the active ingredient. (3) Contact the inner layer slow-release mixture E with the carrier C so that the carrier C loads the inner layer slow-release mixture E; (4) The loaded material is fed into a fluidized bed, and molten outer low-melting-point hydrophobic coating material D or a spray liquid containing the outer low-melting-point hydrophobic coating material D is sprayed into the fluidized bed so that the outer low-melting-point hydrophobic coating material D coats the surface of the carrier C loaded with the inner slow-release mixture E; the temperature of the fluidized bed is controlled to be not lower than the melting point of the outer low-melting-point hydrophobic coating material D, and the temperature of the fluidized bed is controlled to be lower than the melting point of the outer low-melting-point hydrophobic coating material D. After spray drying and cooling solidification, a slow-release defoamer is obtained.

11. The preparation method according to claim 10, characterized in that, In step (2), the inner high-melting-point hydrophobic ester slow-release matrix B is preheated to a molten or softened state before being mixed with the active ingredient A.

12. The preparation method according to claim 10, characterized in that, In step (3), the inner layer slow-release mixture E is loaded onto the surface and / or pores of the carrier C by means of stirring, spraying, kneading and granulation, drum mixing or continuous mixing.

13. The preparation method according to claim 10, characterized in that, In step (4), the temperature of the fluidized bed is within the range of the melting point of the outer low-melting-point hydrophobic coating material D to 15°C above the melting point of the outer low-melting-point hydrophobic coating material D, and the temperature of the fluidized bed is within the range of 1 to 15°C below the melting point of the outer low-melting-point hydrophobic coating material D; after step (4), there is also a crushing and / or screening step.

14. A detergent composition, characterized in that, The detergent composition includes the slow-release defoamer according to any one of claims 1 to 9, wherein the slow-release defoamer accounts for 0.1 to 2.0% of the total mass of the detergent composition.

15. The sustained-release defoamer according to any one of claims 1 to 9 or the sustained-release defoamer prepared by the preparation method according to any one of claims 10 to 13, for use in laundry detergent, liquid detergent or other washing systems for continuous foam control.