Preparation of fluoride-free waterproof agent

Abstract

The invention relates to the technical field of waterproof agent preparation, in particular to preparation of a fluoride-free waterproof agent. The preparation method comprises the following steps: pre-emulsifying octadecyl methacrylate, acrylic acid, an emulsifier and deionized water, and dynamically adjusting the material ratio based on the solid content; carrying out seed emulsion polymerization on part of the pre-emulsion and an ammonium persulfate solution, and dynamically regulating and controlling the dropwise adding rate of an initiator based on the particle size; dropwise adding the remaining materials for nuclear layer polymerization, and supplementing the initiator based on the monomer conversion rate; adding gamma-aminopropyltriethoxysilane and tetraethoxysilane into the core-layer emulsion, adjusting the pH value through ammonia water, carrying out an in-situ sol-gel reaction, and dynamically adjusting and controlling the addition amount of the ammonia water based on Zeta potential to form an organic-inorganic hybrid shell layer; and finally, cooling and filtering to obtain the fluoride-free waterproof agent, and optimizing the dosage of the silane coupling agent in the next batch based on the centrifugal precipitation rate. The problems that an existing fluoride-free waterproof agent is poor in water washing resistance and poor in hand feeling after being washed for multiple times are solved.

Description

Technical Field

[0001] This invention relates to the field of waterproofing agent preparation technology, and in particular to the preparation of a fluorine-free waterproofing agent. Background Technology

[0002] Traditional fluorinated water-repellent agents for textiles are widely used due to their excellent water and oil repellency. However, these fluorinated compounds have environmental persistence, bioaccumulation, and potential toxicity, and their use is being increasingly restricted by regulations. Therefore, developing high-performance, fluorine-free water-repellent agents has become an important research direction in the field of textile chemicals.

[0003] Currently, fluorine-free waterproofing agents on the market are mainly divided into the following categories: acrylic esters, silicones, and waxes. However, these alternative technologies all have significant performance defects: Acrylic waterproofing agents typically provide hydrophobicity through long-chain alkyl groups, but they have a fatal weakness: poor wash resistance. Their waterproofing performance decreases significantly after repeated washing. Furthermore, increasing the cross-linking degree or thickness of the coating in pursuit of higher waterproofing often results in fabrics feeling stiff and rigid.

[0004] Silicone-based waterproofing agents: They can provide a soft feel, but their initial waterproofing performance is usually insufficient and cannot reach the level of fluorinated products or high-performance acrylic products.

[0005] Physical blending modification: such as introducing inorganic nanoparticles to construct a rough structure, but the particles are prone to agglomeration, resulting in poor product stability and unsatisfactory bonding strength with fabric fibers.

[0006] Chinese Patent Publication No. CN117986436A discloses a method for synthesizing a fluorine-free waterproofing agent and the fluorine-free waterproofing agent itself, relating to the technical field of waterproofing agents. The method for synthesizing a fluorine-free waterproofing agent involves using a homogeneous emulsification process and emulsion polymerization to emulsion polymerize butyl acrylate, octadecyl methacrylate, γ-methacryloyloxypropyltrimethoxysilane, functional monomers, and crosslinking monomers. With the addition of emulsifiers, initiators, reducing agents, and pH adjusters, a fluorine-free waterproofing agent free of PFOA and PFOS byproducts can be obtained. The synthesis method is simple. Furthermore, by adding octadecyl methacrylate and γ-methacryloyloxypropyltrimethoxysilane containing hydrophobic structures, the waterproofing and washability of the fluorine-free waterproofing agent can be effectively improved.

[0007] Therefore, the synthesis method and the fluorine-free waterproofing agent described herein have the following problems: 1. During the preparation process, silane monomers are randomly distributed in copolymer form, making it difficult to form a complete and dense coating shell. Furthermore, the focus is on increasing the crosslinking density of the system, resulting in insufficient water resistance and a poor hand feel in fluorine-free waterproofing agents.

[0008] 2. The lack of monitoring and control of key parameters for each step of the preparation process makes it impossible to detect abnormalities in time, resulting in waste of raw materials and poor quality of the final fluorine-free waterproofing agent. Summary of the Invention

[0009] Therefore, the present invention provides a method for preparing a fluorine-free waterproofing agent to overcome the problems of insufficient water resistance and poor hand feel caused by the random distribution of silane monomers in copolymer form in the prior art, the focus on increasing the crosslinking density of the system, and the lack of monitoring and control of key parameters during the preparation process.

[0010] To achieve the above objectives, the present invention provides a method for preparing a fluorine-free waterproofing agent. It includes: 100g of octadecyl methacrylate, 3g of acrylic acid, and 2g of allyloxynonylphenol polyoxyethylene ether ammonium sulfate were mixed with 80g of deionized water and pre-emulsified to obtain a pre-emulsion. The amount of material added during the pre-emulsification process is dynamically adjusted based on the solid content of the pre-emulsified liquid. Add 60g of the pre-emulsion and 20g of 5% ammonium persulfate aqueous solution to the reactor, heat the reaction system to the polymerization reaction temperature, and carry out seed emulsion polymerization to obtain seed emulsion; The dropping rate of the ammonium persulfate aqueous solution is dynamically adjusted during the polymerization process based on the average particle size of the particles in the seed emulsion. The remaining pre-emulsion and 13g of 5% ammonium persulfate aqueous solution were added dropwise to the seed emulsion at a uniform rate to carry out a core-layer polymerization reaction and obtain a core-layer emulsion. The amount of ammonium persulfate added is dynamically adjusted based on the monomer conversion rate of the core emulsion during the reaction process. 8g of γ-aminopropyltriethoxysilane and 5g of tetraethyl orthosilicate were added to the core layer emulsion. The pH of the reaction system was adjusted to the initial pH value with 10% ammonia water. An in-situ sol-gel reaction was carried out, and the reaction occurred on the surface of the polymer particles of the core layer emulsion to form a core-shell structure emulsion with an organic-inorganic hybrid shell. The dropping rate of the ammonia solution is dynamically adjusted based on the absolute value of the Zeta potential of the core-shell emulsion. The core-shell emulsion was cooled to room temperature, filtered, and collected to obtain the fluorine-free waterproofing agent. The amount of γ-aminopropyltriethoxysilane added in the next batch is determined based on the centrifugal sedimentation rate of the fluorine-free waterproofing agent obtained in the current batch.

[0011] Furthermore, the process of determining the amount of material added during the pre-emulsification process based on the solid content of the pre-emulsified liquid includes, 100g of octadecyl methacrylate, 3g of acrylic acid, and 2g of allyloxynonylphenol polyoxyethylene ether ammonium sulfate were slowly mixed with 80g of deionized water at 300r / min to obtain the first mixed solution. The first mixed solution was placed in an emulsification reactor and stirred at 800 r / min and emulsification temperature of 45℃ for 45 min for pre-emulsification treatment. When the pre-emulsification process reaches the 20th minute, a small amount of pre-emulsified liquid sample is taken and the solid content is obtained; The solid content is compared with a preset solid content range; Based on the fact that the solid content is lower than the lower limit of the preset solid content range, the acrylic acid and the allyloxynonylphenol polyoxyethylene ether ammonium sulfate are added to the pre-emulsification treatment by multiplying the absolute difference between the solid content and the lower limit of the preset solid content range by the original mass ratio before the addition.

[0012] Furthermore, the process of determining and dynamically adjusting the amount of material added during the pre-emulsification process based on the solid content of the pre-emulsified liquid also includes, Based on the fact that the solid content is higher than the upper limit of the preset solid content range, it is determined that 2% of the total mass of the system of deionized water will be added, which is the absolute difference between the solid content and the upper limit of the preset solid content range.

[0013] Furthermore, the process of determining the dropping rate of the ammonium persulfate aqueous solution during polymerization based on the average particle size in the seed emulsion includes, The reaction system was heated to the polymerization reaction temperature of 80°C at a heating rate of 5°C / min under an argon atmosphere. Add 5g of the ammonium persulfate aqueous solution to the reactor at a stirring speed of 400r / min in one go; The remaining 15g of the ammonium persulfate aqueous solution was transferred to a constant pressure dropping funnel and added dropwise to the reactor at a first initial dropping rate of 0.5ml / min for a total reaction time of 60min. A small amount of emulsion sample was taken from the reaction system and cooled to room temperature at 30 min of reaction time. Obtain the average particle size of the particles in the emulsion sample; The average particle size is compared with a preset average particle size range; Based on the fact that the average particle size is lower than the preset lower limit of the average particle size, the dropping acceleration rate is increased by multiplying the absolute difference between the average particle size and the preset lower limit of the average particle size range by 0.03 ml / min, based on the first initial dropping acceleration rate.

[0014] Furthermore, the process of determining the dropping rate of the ammonium persulfate aqueous solution during polymerization based on the average particle size in the seed emulsion also includes, Based on the fact that the average particle size is higher than the preset upper limit of the average particle size, the dropping acceleration rate is determined to be reduced by multiplying the absolute difference between the average particle size and the upper limit of the preset average particle size range by 0.02 ml / min, based on the first initial dropping acceleration rate.

[0015] Furthermore, the process of dynamically adjusting the amount of ammonium persulfate aqueous solution added based on the monomer conversion rate of the core emulsion during the reaction process includes, Take 40g of the pre-emulsion and 13g of ammonium persulfate aqueous solution; 40g of the pre-emulsion was transferred to a constant pressure dropping funnel and 7g of the ammonium persulfate aqueous solution was added at once to obtain a second mixed solution; All of the seed emulsions were transferred to a four-necked flask reactor and maintained at 80°C and 400 r / min. 3.5 g of the ammonium persulfate aqueous solution was added at once, and the second mixed solution was added dropwise to the four-necked flask reactor at a second initial drop rate of 1.0 ml / min. The total reaction time was 90 min. The remaining 2.5g of the ammonium persulfate aqueous solution was used as a backup solution; After all the second mixed solution has been added and the reaction has proceeded for 70 minutes, a small amount of core emulsion sample is taken from the reaction system and the monomer conversion rate is obtained. The monomer conversion rate is compared with the preset monomer conversion rate; Based on the fact that the monomer conversion rate is less than the preset monomer conversion rate, the absolute difference between the monomer conversion rate and the preset monomer conversion rate is multiplied by 20% of the spare solution and added to the reaction system at once as the supplementary amount.

[0016] Furthermore, the process of determining the dynamic adjustment of the ammonia dripping rate based on the absolute value of the Zeta potential of the core-shell emulsion includes, 8g of γ-aminopropyltriethoxysilane was added to the core emulsion at once and stirred at 400r / min for 10min to obtain a third mixed solution; Add 5g of tetraethyl orthosilicate to the third mixed solution at once and stir at 400r / min for 10min to obtain the fourth mixed solution; The ammonia solution was added dropwise to the fourth mixed solution at a third initial dropping rate of 1.0 ml / min at a speed of 500 r / min, and the in-situ sol-gel reaction was initiated at 65°C. The total reaction time was 240 min. When the in-situ sol-gel reaction was carried out for 60 minutes, a small amount of core-shell emulsion sample was taken out from the reaction system and the absolute value of the Zeta potential was obtained. The absolute value of the Zeta potential is compared with a preset range of absolute potential values; Based on the fact that the absolute value of the Zeta potential is lower than the lower limit of the preset absolute value range, the drip acceleration rate is increased by multiplying the absolute difference between the absolute value of the Zeta potential and the lower limit of the preset absolute value range by 0.05 ml / min, based on the current drip acceleration rate.

[0017] Furthermore, the process of determining the dynamic adjustment rate of the ammonia droplet based on the absolute value of the Zeta potential of the core-shell emulsion also includes, Based on the fact that the absolute value of the Zeta potential is higher than the upper limit of the preset absolute value range, the drip acceleration rate is determined to be reduced by multiplying the absolute difference between the absolute value of the Zeta potential and the upper limit of the preset absolute value range by 0.02 ml / min, based on the current drip acceleration rate.

[0018] Furthermore, the process of determining the amount of γ-aminopropyltriethoxysilane to be added in the next batch based on the centrifugal sedimentation rate of the fluorine-free waterproofing agent obtained in the current batch includes, The core-shell emulsion was cooled to 25°C; The fluorine-free waterproofing agent is obtained by filtering through a 500-mesh filter cloth and collecting the filtrate. The fluorine-free waterproofing agent was sampled and the centrifugal sedimentation rate was obtained; The centrifugal sedimentation rate is compared with a preset centrifugal sedimentation rate range; Based on the fact that the centrifugal sedimentation rate is lower than the lower limit of the preset centrifugal sedimentation rate range, the absolute difference between the centrifugal sedimentation rate and the preset lower limit of the centrifugal sedimentation rate is multiplied by 0.05g as the reduction amount of the next batch of γ-aminopropyltriethoxysilane.

[0019] Furthermore, the process of determining the amount of γ-aminopropyltriethoxysilane to be added in the next batch based on the centrifugal sedimentation rate of the fluorine-free waterproofing agent obtained in the current batch also includes, Based on the fact that the centrifugal sedimentation rate is higher than the upper limit of the preset centrifugal sedimentation rate range, the absolute difference between the centrifugal sedimentation rate and the upper limit of the preset centrifugal sedimentation rate range is multiplied by 0.1g as the increase amount of the γ-aminopropyltriethoxysilane in the next batch.

[0020] Compared with existing technologies, the beneficial effects of this invention lie in its multi-level closed-loop quality control system, which establishes a system encompassing "pre-emulsion solid content – ​​seed emulsion particle size – core-layer polymerization conversion rate – hybridization process Zeta potential – product centrifugal sedimentation rate" throughout the entire preparation process. This system achieves precise control from raw materials to the final product, ensuring that intermediate products at each step meet preset quality standards. Consequently, it guarantees that the final fluorine-free waterproofing agent product possesses a highly consistent "polymer core – organic-inorganic hybrid shell" structure. This "polymer core – organic-inorganic hybrid shell" structure synergistically leverages the flexible support of the polymer core and the micro-nano roughness and strong interfacial bonding of the hybrid shell, enabling the product to possess excellent initial waterproofing, superior wash resistance and durability, and a pleasant fabric feel while remaining completely fluorine-free. This effectively solves the technical challenges of traditional fluorine-free waterproofing agents exhibiting limited performance and insufficient durability.

[0021] Furthermore, by taking samples at 20 minutes into the pre-emulsification process and dynamically adjusting the amount of deionized water or mixed monomers added based on real-time monitoring of solid content, the present invention precisely stabilizes the solid content of the pre-emulsified liquid within the range of 40% to 50%, ensuring that the pre-emulsified liquid has optimal viscosity and stability. This provides a precursor with uniform particle size and stable reactivity for subsequent polymerization reactions, thus ensuring batch-to-batch consistency of the final product performance from the source.

[0022] Furthermore, this invention samples and monitors the average particle size at 30 minutes of seed polymerization and dynamically adjusts the initiator droplet acceleration rate to precisely control the particle size of the seed emulsion within a preset range of 65-75 nanometers. When the particle size is too small, increasing the initiator droplet acceleration rate successfully promotes particle growth, ensuring the monodispersity and regularity of the seed particles. This lays a crucial dimensional foundation for the subsequent perfect coating of the core layer and the formation of a regular core-shell structure.

[0023] Furthermore, this invention ensures a conversion rate of no less than 98% by monitoring the monomer conversion rate in the later stages of core-shell polymerization and adding initiators as needed, thereby guaranteeing the integrity of the core-shell structure and low residual monomer content. More importantly, by monitoring the Zeta potential of the core-shell emulsion sample in real time during the hybridization reaction and adjusting the ammonia droplet acceleration rate accordingly, its absolute value is stabilized at a high level of 28-32 mV, effectively maintaining the electrostatic repulsion between particles and ensuring the dense, uniform, and stable formation of the organic-inorganic hybrid shell on the core-shell surface. This is the structural basis for obtaining excellent wash resistance.

[0024] Furthermore, this invention establishes a continuous optimization mechanism across batches by adjusting the amount of silane coupling agent added in the next batch based on the centrifugal sedimentation rate of the current batch of products. When the centrifugal sedimentation rate is lower than the lower limit, the amount of silane coupling agent is reduced in the next batch. This can proactively compensate for minor fluctuations in raw materials or environmental factors, enabling the production process to learn and continuously optimize itself. As a result, it can significantly improve the overall qualification rate and quality stability of products in long-term industrial production.

[0025] Furthermore, this invention successfully prepared a fluorine-free waterproofing agent with a "polymer core-organic-inorganic hybrid shell" structure through a multi-step synergistic process of "pre-emulsification-seed polymerization-core layer polymerization-in-situ hybridization" and closed-loop quality control throughout the entire process. The fluorine-free waterproofing agent obtained by the preparation method shown in Examples 1-3 was formulated into a 50g / L working solution. After treating pure cotton fabrics, the initial contact angle was as high as 148° or more, and the contact angle remained above 139° after 20 washes. At the same time, the hand feel score reached 4.2 points or more, which comprehensively surpassed the performance of traditional acrylic and silicone waterproofing agents. Under completely fluorine-free conditions, it solved the industry technical bottleneck of the difficulty in achieving high waterproofness, high wash resistance and excellent hand feel at the same time. Attached Figure Description

[0026] Figure 1 This is a schematic diagram illustrating the preparation process of the fluorine-free waterproofing agent according to an embodiment of the present invention; Figure 2 This is a schematic diagram illustrating the preparation steps of the fluorine-free waterproofing agent according to an embodiment of the present invention; Figure 3 This is a logic block diagram illustrating how the amount of material added during the pre-emulsification process is dynamically adjusted based on the solid content in the pre-emulsified liquid, according to an embodiment of the present invention. Figure 4 This is a logic block diagram illustrating how the dropping rate of the initiator solution is dynamically adjusted based on the average particle size of the seed emulsion sample, according to an embodiment of the present invention. Figure 5 This is a logic block diagram illustrating how to dynamically adjust the amount of ammonium persulfate solution added based on the monomer conversion rate of the core emulsion sample, as described in an embodiment of the present invention. Figure 6 This is a logic block diagram illustrating how the dropping acceleration rate of ammonia is dynamically adjusted based on the absolute value of the Zeta potential of a core-shell emulsion sample, according to an embodiment of the present invention. Figure 7 This is a logic block diagram illustrating how to adjust the amount of γ-aminopropyltriethoxysilane added in the next batch based on the centrifugation sedimentation rate of a fluorine-free waterproofing agent sample, as described in an embodiment of the present invention. Detailed Implementation

[0027] To make the objectives and advantages of the present invention clearer, the present invention will be further described below with reference to embodiments; it should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention.

[0028] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0029] It should be noted that in the description of this invention, the terms "upper", "lower", "left", "right", "inner", "outer", etc., which indicate directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings. This is only for the convenience of description and is not intended to indicate or imply that the device or element must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of this invention.

[0030] Please see Figures 1 to 2 As shown, Figure 1 This is a schematic diagram illustrating the preparation process of the fluorine-free waterproofing agent according to an embodiment of the present invention; Figure 2 This is a schematic diagram illustrating the preparation steps of the fluorine-free waterproofing agent according to an embodiment of the present invention.

[0031] The preparation of the fluorine-free waterproofing agent according to embodiments of the present invention includes: Step S1: Mix acrylic long-chain alkyl ester monomers, functional monomers and emulsifiers with deionized water and perform pre-emulsification treatment to obtain a pre-emulsion. Step S11: Determine the amount of material to be added during the pre-emulsification process based on the solid content of the pre-emulsified liquid; Step S2: Add a portion of the pre-emulsion obtained in step 1 and the initiator solution to the reactor, heat the reaction system to the polymerization reaction temperature, and carry out seed emulsion polymerization to obtain a seed emulsion; Step S21: Based on the average particle size of the seed emulsion, determine the dropping rate of the initiator solution to be dynamically adjusted during the polymerization process in order to obtain a seed emulsion with qualified particle size. Step S3: The remaining pre-emulsion and the initiator solution are added dropwise at a uniform rate to the seed emulsion obtained in step S2 to carry out a core-layer polymerization reaction and obtain a core-layer emulsion. Step S31: Determine the amount of initiator solution to be added dynamically based on the monomer conversion rate of the core emulsion during the reaction process; Step S4: Add silane coupling agent and inorganic silicon source to the core layer emulsion obtained in step S3. First, adjust the pH value of the reaction system to the initial pH value with an alkaline pH adjuster, and carry out in-situ sol-gel reaction. The reaction occurs on the surface of the polymer particles in the core layer emulsion to form a core-shell structure emulsion with an organic-inorganic hybrid shell. Step S41: Based on the absolute value of the Zeta potential of the core-shell emulsion, determine the dropping rate of the alkaline pH adjuster to ensure the stable formation of the hybrid shell, and obtain the core-shell emulsion. Step S5: Cool and filter the core-shell structure emulsion obtained in step 4 to obtain the fluorine-free waterproofing agent; Step S51: Based on the centrifugal sedimentation rate of the fluorine-free waterproofing agent obtained in the current batch, determine the amount of silane coupling agent to be added in the next batch.

[0032] Specifically, this invention constructs a multi-level closed-loop quality control system throughout the entire preparation process, encompassing "pre-emulsion solid content – ​​seed emulsion particle size – core-layer polymerization conversion rate – hybridization process Zeta potential – product centrifugal sedimentation rate." This system achieves precise control from raw materials to the final product, ensuring that intermediate products at each step meet preset quality standards. This guarantees that the final fluorine-free waterproofing agent product possesses a highly consistent "polymer core – organic-inorganic hybrid shell" structure. The "polymer core – organic-inorganic hybrid shell" structure synergistically leverages the flexible support of the polymer core and the micro-nano roughness and strong interfacial bonding of the hybrid shell, enabling the product to possess excellent initial waterproofing, superior wash resistance and durability, and a pleasant fabric feel while remaining completely fluorine-free. This effectively solves the technical challenges of traditional fluorine-free waterproofing agents' limited performance and insufficient durability.

[0033] In this embodiment of the invention, the process of obtaining the pre-emulsion includes: 100g of octadecyl methacrylate, 3g of acrylic acid, and 2g of allyloxynonylphenol polyoxyethylene ether ammonium sulfate were slowly mixed with 80g of deionized water at a stirring speed of 300r / min. The mixture was stirred continuously until all materials were added to obtain the first mixed solution.

[0034] The first mixed solution is placed in an emulsification reactor. The emulsification speed is 600 r / min-1000 r / min, preferably 800 r / min, the emulsification temperature is 25℃-60℃, preferably 45℃, and the total emulsification time is 30 min-60 min, preferably 45 min. Stirring is started under these conditions to pre-emulsify the mixed system, and the pre-emulsified liquid is obtained after the pre-emulsification treatment.

[0035] Understandably, octadecyl methacrylate, as a long-chain alkyl monomer, provides the main hydrophobic properties; acrylic acid, as a functional monomer, has a carboxyl group that can participate in subsequent reactions and improve emulsion stability; and allyloxynonylphenol polyoxyethylene ether ammonium sulfate, as a reactive emulsifier, can become part of the polymer after polymerization, avoiding performance degradation caused by the migration of small molecule emulsifiers.

[0036] In this embodiment of the invention, the octadecyl methacrylate used is industrial grade with a purity ≥98%; the acrylic acid is chemically pure with a purity ≥99%; and the emulsifier is a commercially available reactive emulsifier, such as allyloxynonylphenol polyoxyethylene ether ammonium sulfate.

[0037] Please see Figure 3 As shown, it is a logic block diagram of the present invention for determining the amount of material added during the pre-emulsification process based on the solid content in the pre-emulsified liquid.

[0038] Specifically, at the 20th minute of the pre-emulsification process, a sample of the pre-emulsified liquid is taken for testing. Based on the comparison between the solid content in the pre-emulsified liquid and a preset solid content range, the amount of material added during the pre-emulsification process is dynamically adjusted. If the solid content is lower than the lower limit of the preset solid content range, then it is determined that the acrylic acid and the allyloxynonylphenol polyoxyethylene ether ammonium sulfate will be added to the pre-emulsification process being performed. That is, for every 1% lower than the lower limit of the preset solid content range, 1.5% of the total mass of the system at this moment will be added according to the original mass ratio before the addition. The total addition amount is the product of the absolute difference between the solid content and the lower limit of the preset solid content range and 1.5%. If the solid content is higher than the upper limit of the preset solid content range, then it is determined to add deionized water to the pre-emulsification process being performed. That is, for every 1% increase in the solid content above the upper limit of the preset solid content range, 2% of the total mass of the system of deionized water is added. The total amount added is the product of the absolute difference between the solid content and the upper limit of the preset solid content range and 2%.

[0039] It is worth noting that after the addition is completed, pre-emulsification treatment should continue at the original speed and temperature until the total treatment time reaches 45 minutes.

[0040] In this embodiment of the invention, the solid content is detected according to the GB / T 1725-2007 standard, using a rapid solid content analyzer, such as a Mettler Toledo HG63, and dried to constant weight at 105°C.

[0041] In this embodiment of the invention, the preset solid content range is [40%, 50%]. The preset solid content range is an optimized range determined based on previous screening experiments, which can ensure reaction stability and product performance.

[0042] Specifically, this invention takes samples at 20 minutes into the pre-emulsification process and dynamically adjusts the amount of deionized water or mixed monomers added based on real-time monitoring of solid content. This ensures that the solid content of the pre-emulsified liquid is precisely stabilized within the range of 40% to 50%, guaranteeing that the pre-emulsified liquid has optimal viscosity and stability. This provides a precursor with uniform particle size and stable reactivity for subsequent polymerization reactions, thus ensuring batch-to-batch consistency of the final product performance from the source.

[0043] In this embodiment of the invention, the process of obtaining the seed emulsion includes: Take 60g of the qualified pre-emulsion and add it to a four-necked flask reactor. Under an argon atmosphere, heat the reaction system to the polymerization temperature of 80°C at a heating rate of 5°C / min, and start stirring at a speed of 400 rpm. Once the system temperature stabilizes at 80°C, quickly add 5g of a 5% ammonium persulfate aqueous solution as the initial initiator to the reactor in one go. Transfer the remaining 15g of the 5% ammonium persulfate aqueous solution to a constant-pressure dropping funnel, and immediately begin subsequent dropping operations at an initial dropping rate of 0.5ml / min. The total reaction time is 60min.

[0044] It is understandable that ammonium persulfate, as a water-soluble thermal decomposition initiator, generates sulfate anion free radicals under heating conditions, which are used to initiate the emulsion polymerization of acrylate monomers. By controlling the initial addition of a portion of pre-emulsion for seed polymerization, small-diameter latex particles with good monodispersity can be formed, serving as "seeds" for the subsequent formation of the core layer.

[0045] Please see Figure 4 As shown, it is a logic block diagram of how the dropping rate of the initiator solution is dynamically adjusted based on the average particle size of the seed emulsion sample in an embodiment of the present invention.

[0046] Specifically, when the seed emulsion polymerization reaction reaches 30 minutes, a small amount of seed emulsion sample is taken from the reaction system, cooled to room temperature, and its average particle size is measured using a laser particle size analyzer. Based on the comparison between the average particle size and a preset average particle size range, the dropping rate of the initiator solution is dynamically adjusted during the polymerization process. If the average particle size is lower than the lower limit of the preset average particle size range, the dropping rate of the initiator solution is accelerated. That is, for every 1 nm that the average particle size is lower than the lower limit of the preset average particle size range, the dropping rate of the initiator solution is increased by 0.03 ml / min based on the first initial dropping rate. The accelerated dropping rate of the initiator solution should not exceed 0.8 ml / min. If the average particle size is higher than the upper limit of the preset average particle size range, then the dropping rate of the initiator solution is reduced. That is, for every 1 nm that the average particle size is higher than the upper limit of the preset average particle size range, the dropping rate of the initiator solution is reduced by 0.02 ml / min based on the first initial dropping rate. The reduced dropping rate of the initiator solution should not be less than 0.5 ml / min.

[0047] It is worth noting that after adjusting the dropping rate of the initiator solution, the seed emulsion polymerization reaction continues at the polymerization reaction temperature of 80°C under argon atmosphere protection until the total reaction time reaches 60 min. Before determining the end of the reaction, it should be ensured that all the remaining 15 g of 5% ammonium persulfate aqueous solution in the constant pressure dropping funnel has been added.

[0048] In this embodiment of the invention, the preset average particle size range is [65nm, 75nm]. The preset average particle size range is an optimized range determined based on previous screening experiments, which can ensure reaction stability and product performance.

[0049] In this embodiment of the invention, the average particle size is measured three times at 25°C using a laser particle size analyzer, such as the Malvern Panaco Zetasizer Nano ZS90, and the average value is taken.

[0050] Specifically, this invention samples and monitors the average particle size at 30 minutes of seed polymerization and dynamically adjusts the initiator drop rate to precisely control the particle size of the seed emulsion within a preset range of 65-75 nanometers. When the particle size is too small, increasing the initiator drop rate successfully promotes particle growth, ensuring the monodispersity and regularity of the seed particles. This lays a crucial dimensional foundation for the subsequent perfect coating of the core layer and the formation of a regular core-shell structure.

[0051] In this embodiment of the invention, the process of obtaining the core layer emulsion includes: Transfer all the seed emulsion obtained in step 2 to another clean four-necked flask reactor, maintain the system temperature at 80°C and the stirring speed at 400 r / min, take 40 g of qualified pre-emulsion and 13 g of 5% ammonium persulfate aqueous solution as initiator, transfer 40 g of the pre-emulsion to another clean constant pressure dropping funnel, and add 7 g of the ammonium persulfate aqueous solution to the constant pressure dropping funnel at once to mix with the pre-emulsion to obtain a second mixed solution.

[0052] At the start of core-layer polymerization, 3.5g of the ammonium persulfate aqueous solution is added to the four-necked flask reactor at once and mixed with the seed solution. Then, the second mixed solution is immediately added dropwise to the four-necked flask reactor at a second initial dropping rate of 1.0ml / min. Finally, the remaining 2.5g of the ammonium persulfate aqueous solution is transferred to a clean constant-pressure dropping funnel for later use. The total reaction time for core-layer polymerization is 90min, and the addition of the mixed solution should be completed within the first 50min.

[0053] Please see Figure 5 As shown, it is a logic block diagram of an embodiment of the present invention for determining the amount of ammonium persulfate aqueous solution to be added dynamically based on the monomer conversion rate of the core layer emulsion sample.

[0054] Specifically, when the second mixed solution has been completely added and the reaction has proceeded for 70 minutes, a small amount of core emulsion sample is taken from the reaction system, cooled, and then the monomer conversion rate of the sample is determined by gas chromatography. Based on the comparison between the monomer conversion rate and the preset monomer conversion rate, the amount of ammonium persulfate aqueous solution to be added is dynamically adjusted. If the monomer conversion rate is less than the preset monomer conversion rate, then 2.5g of the ammonium persulfate aqueous solution is added to the reaction system. That is, for every 1% decrease in the monomer conversion rate from the preset monomer conversion rate, 20% of the 2.5g ammonium persulfate aqueous solution is added to the reaction system at once. After the addition is completed, the reaction is terminated after 20 minutes. The amount of ammonium persulfate aqueous solution added should not exceed 2.5g. If the monomer conversion rate is greater than or equal to the preset monomer conversion rate, then it is determined that no additional monomer is needed, and the remaining reaction time can be completed.

[0055] In this embodiment of the invention, the preset monomer conversion rate ranges from 95% to 99%, with a preferred value of 98%. The preset monomer conversion rate is an optimized range determined based on previous screening experiments, which can ensure reaction stability and product performance. The preferred range and preferred value can be determined according to actual conditions, and are not specifically limited here.

[0056] In this embodiment of the invention, the monomer conversion rate is determined by gas chromatography, for example, an Agilent 7890B model, using the internal standard method.

[0057] In this embodiment of the invention, the process of obtaining the core-shell structured emulsion includes: Take all of the core layer emulsion obtained in step S3, first add 8g of γ-aminopropyltriethoxysilane to the core layer emulsion at a time and react at a stirring rate of 400r / min for 10min to obtain a third mixed solution, so that the γ-aminopropyltriethoxysilane is fully adsorbed on the polymer surface. Then add 5g of tetraethyl orthosilicate to the third mixed solution at a time and continue stirring at a stirring rate of 400r / min for 10min to obtain a fourth mixed solution, so that the tetraethyl orthosilicate is uniformly dispersed in the system.

[0058] The stirring rate was increased to 500 r / min, and 10% ammonia water was added dropwise to the fourth mixture through the constant pressure dropping funnel at a third initial dropping rate of 1.0 ml / min. The initial pH value of the fourth mixture was finely adjusted to 9.3-9.6, preferably 9.5 in this invention, and the reaction temperature was maintained at 65°C to start the in-situ sol-gel reaction. The total reaction time was 240 min.

[0059] It is understandable that the long organic chain of γ-aminopropyltriethoxysilane is compatible with the polymer core, and its hydrolyzed silanol groups can undergo condensation reactions with the silanol groups generated by the hydrolysis of tetraethyl orthosilicate, jointly constructing a hybrid network on the surface of the core layer particles. Ammonia water is used as a catalyst, and its dosage directly controls the rate balance of hydrolysis and condensation reactions. By monitoring the Zeta potential to adjust the pH, it is possible to ensure that the surface charge of the particles is always maintained at a high level, thereby ensuring the stability of the emulsion during the formation of the hybrid shell through electrostatic repulsion, and finally obtaining a dense coating structure.

[0060] Please see Figure 6 As shown, it is a logic block diagram of how the dropping rate of ammonia is dynamically adjusted based on the absolute value of the Zeta potential of the core-shell emulsion sample in an embodiment of the present invention.

[0061] Specifically, at the 60-minute mark of the in-situ sol-gel reaction, a small amount of core-shell emulsion sample was taken from the reaction system. After cooling to 25°C, the absolute value of the Zeta potential was measured using a Zeta potential and nanoparticle size analyzer. Based on the comparison between the absolute value of the Zeta potential and the preset absolute value, the dropping rate of ammonia was dynamically adjusted. If the absolute value of the Zeta potential is lower than the lower limit of the preset absolute value range, then the dropping rate of ammonia is increased. That is, for every 1mV that the absolute value of the Zeta potential is lower than the lower limit of the preset absolute value range, the dropping rate of ammonia is increased by 0.05ml / min based on the current dropping rate. The increased dropping rate of ammonia should not exceed 2.0ml / min. If the absolute value of the Zeta potential is higher than the upper limit of the preset absolute value range, then the dropping rate of ammonia is reduced. That is, for every 1mV that the absolute value of the Zeta potential exceeds the upper limit of the preset absolute value range, the dropping rate of ammonia is reduced by 0.02ml / min based on the current dropping rate. The reduced dropping rate of ammonia should not be lower than 0.5ml / min.

[0062] In this embodiment of the invention, the preset potential absolute value range is [28mV, 32mV]. The preset potential absolute value range is an optimized range determined based on previous screening experiments, which can ensure reaction stability and product performance.

[0063] In this embodiment of the invention, the dynamic adjustment of the ammonia dripping rate is continuously carried out during the reaction process. After the first sampling adjustment, the next sampling adjustment is carried out every 30 minutes until the total reaction time of 240 minutes is reached.

[0064] Specifically, this invention ensures a conversion rate of no less than 98% by monitoring the monomer conversion rate in the later stages of core-shell polymerization and adding initiators as needed, thereby guaranteeing the integrity of the core-shell structure and low residual monomer content. More importantly, by monitoring the Zeta potential of the core-shell emulsion sample in real time during the hybridization reaction and adjusting the ammonia droplet acceleration rate accordingly, its absolute value is stabilized at a high level of 28-32 mV, effectively maintaining the electrostatic repulsion between particles and ensuring the dense, uniform, and stable formation of the organic-inorganic hybrid shell on the core-shell surface. This is the structural basis for obtaining excellent wash resistance.

[0065] In this embodiment of the invention, the process of obtaining the fluorine-free waterproofing agent includes: Take all of the core-shell structured emulsion obtained in step S4, cool the core-shell structured emulsion to 25°C, and then filter the rational structured emulsion using a 500-mesh filter cloth. Collect the filtrate to obtain the fluorine-free waterproofing agent.

[0066] Please see Figure 7 As shown, it is a logic block diagram of an embodiment of the present invention for determining the amount of γ-aminopropyltriethoxysilane to be added in the next batch based on the centrifugation sedimentation rate of the fluorine-free waterproofing agent sample.

[0067] Specifically, the collected filtrate is sampled, and the centrifugal sedimentation rate is determined using a centrifugal stability analyzer. Based on the comparison between the centrifugal sedimentation rate and a preset centrifugal sedimentation rate range, the amount of γ-aminopropyltriethoxysilane added in the next batch is adjusted. If the centrifugal sedimentation rate is lower than the lower limit of the preset centrifugal sedimentation rate range, then it is determined that the amount of γ-aminopropyltriethoxysilane added in the next batch will be reduced. That is, for every 0.1% lower the centrifugal sedimentation rate than the preset lower limit of the centrifugal sedimentation rate, the amount of γ-aminopropyltriethoxysilane added will be reduced by 0.05g based on the 8g added in step S4. The amount of γ-aminopropyltriethoxysilane added after the reduction should not be less than 7.0g. If the centrifugal sedimentation rate is higher than the upper limit of the preset centrifugal sedimentation rate range, then it is determined that the amount of γ-aminopropyltriethoxysilane added in the next batch will be increased. That is, for every 0.1% increase in the centrifugal sedimentation rate above the upper limit of the preset centrifugal sedimentation rate range, the amount of γ-aminopropyltriethoxysilane added will be increased by 0.1g based on the 8g added in step S4. The increased amount of γ-aminopropyltriethoxysilane added should not exceed 9.0g.

[0068] In this embodiment of the invention, the centrifugal sedimentation rate is obtained by using a centrifugal stability analyzer, such as the LUMiFuge series stability analyzer, and by using a 50mL centrifuge tube, taking 40mL of sample and centrifuging at 3000r / min for 30min. After centrifugation, the volume of sediment at the bottom of the centrifuge tube is measured, and the ratio of the sediment volume to the total volume of the sample in the centrifuge tube is calculated to obtain the centrifugal sedimentation rate.

[0069] In this embodiment of the invention, the preset centrifugal sedimentation rate range is [0.7%, 1%]. The preset centrifugal sedimentation rate range is an optimized range determined based on previous screening experiments, which can ensure reaction stability and product performance.

[0070] Specifically, this invention establishes a continuous optimization mechanism across batches by adjusting the amount of silane coupling agent added in the next batch based on the centrifugal sedimentation rate of the current batch of products. When the centrifugal sedimentation rate is lower than the lower limit, the amount of silane coupling agent is reduced in the next batch. This can proactively compensate for minor fluctuations in raw materials or environmental factors, enabling the production process to learn and continuously optimize itself, thereby significantly improving the overall qualification rate and quality stability of products in long-term industrial production. Example

[0071] (1) 100g of octadecyl methacrylate, 3g of acrylic acid and 2g of allyloxynonylphenol polyoxyethylene ether ammonium sulfate were mixed with 80g of deionized water at 300 r / min to obtain a preliminary mixture system; the preliminary mixture system was pre-emulsified at 800 r / min and 45℃ for 45 min; at the 20th minute, the solid content was measured to be 43%, and no adjustment was made. The treatment was continued until the end of the total time to obtain a qualified pre-emulsion.

[0072] (2) Take 60g of the qualified pre-emulsion and add it to a four-necked flask; heat it to 80℃ under argon protection, take 20g of 5% ammonium persulfate aqueous solution, add 5g of 5% ammonium persulfate aqueous solution to the four-necked flask at one time, and at the same time start to add the remaining 15g of ammonium persulfate aqueous solution dropwise at a rate of 0.5 mL / min. The total reaction time is 60min; take a sample at 30min and measure the average particle size as 68nm. Do not adjust. Continue the reaction until the total time is over to obtain a qualified seed emulsion.

[0073] (3) Maintain all the seed emulsions at 80℃ and 400 r / min; take 13g of 5% ammonium persulfate aqueous solution and add 3.5g of 5% ammonium persulfate aqueous solution as the initial initiator to the system; mix 40g of the remaining pre-emulsion from step S1 with 7g of the ammonium persulfate aqueous solution and add it dropwise at a rate of 1.0 mL / min, which is completed within 50 min; reserve 2.5g of the ammonium persulfate aqueous solution; when the dropwise addition is completed and the reaction proceeds to 70 min, the monomer conversion rate is measured to be 96%; based on the conversion rate being less than 98%, add 1.0g of the reserve initiator solution to the system at once, and extend the reaction by 20 min after the addition is completed to obtain a qualified core layer emulsion.

[0074] (4) Add 8g of γ-aminopropyltriethoxysilane to all qualified core emulsions and react at 400 r / min for 10 min; add 5g of tetraethyl orthosilicate and continue stirring for 10 min; increase the rotation speed to 500 r / min and add 10% ammonia water at a rate of 1.0 mL / min to precisely adjust the initial pH value of the reaction system to 9.5, and carry out in-situ sol-gel reaction at 65℃ for a total time of 240 min; at the 60 min, the absolute value of the Zeta potential was measured to be 26 mV. Based on its value being lower than 28 mV, the dropping rate of ammonia water was increased by 0.1 mL / min to 1.1 mL / min; the subsequent monitoring showed that the potential value was within the qualified range and no further adjustment was made, thus obtaining the core-shell structure emulsion.

[0075] (5) Cool the core-shell emulsion to 25°C, filter it using a 500-mesh filter cloth, collect the filtrate to obtain the fluorine-free waterproofing agent; take a sample and measure the centrifugal precipitation rate of 0.8%, and determine that the amount of γ-aminopropyltriethoxysilane added in the next batch should remain unchanged at 8.0g. Example

[0076] (1) 100g of octadecyl methacrylate, 3g of acrylic acid and 2g of allyloxynonylphenol polyoxyethylene ether ammonium sulfate were mixed with 80g of deionized water at 300 r / min to obtain a preliminary mixed system; the preliminary mixed system was pre-emulsified at 800 r / min and 45℃ for 45 min; at the 20th minute, the solid content was measured to be 48%, and no adjustment was made. The treatment continued until the end of the total time to obtain a qualified pre-emulsion.

[0077] (2) Take 60g of the qualified pre-emulsion and add it to a four-necked flask; heat it to 80℃ under argon protection, take 20g of 5% ammonium persulfate aqueous solution, add 5g of 5% ammonium persulfate aqueous solution to the four-necked flask at one time, and at the same time start to add the remaining 15g of ammonium persulfate aqueous solution dropwise at a rate of 0.5 mL / min. The total reaction time is 60min; at the 30min, the average particle size was measured to be 72nm. No adjustment was made. The reaction continued until the end of the total time to obtain a qualified seed emulsion.

[0078] (3) Maintain all the seed emulsions at 80℃ and 400 r / min; take 13g of 5% ammonium persulfate aqueous solution and add 3.5g of 5% ammonium persulfate aqueous solution as the initial initiator to the system; mix 40g of the remaining pre-emulsion from step S1 with 7g of the ammonium persulfate aqueous solution and add it dropwise at a rate of 1.0 mL / min, which is completed within 50 min; reserve 2.5g of the ammonium persulfate aqueous solution; when the dropwise addition is completed and the reaction proceeds to 70 min, the monomer conversion rate is measured to be 97%; based on the conversion rate being less than 98%, add 0.5g of the reserve initiator solution to the system at once, and extend the reaction by 20 min after the addition is completed to obtain a qualified core layer emulsion.

[0079] (4) Add 8g of γ-aminopropyltriethoxysilane to all qualified core emulsions and react at 400 r / min for 10 min; add 5g of tetraethyl orthosilicate and continue stirring for 10 min; increase the rotation speed to 500 r / min and add 10% ammonia water at a rate of 1.0 mL / min to precisely adjust the initial pH value of the reaction system to 9.5, and carry out in-situ sol-gel reaction at 65℃ for a total time of 240 min; at 60 min, the absolute value of the Zeta potential was measured to be 35mV. Based on its higher than 32mV, the dropping rate of ammonia water was reduced by 0.09 mL / min to 0.91 mL / min; the subsequent monitoring of the potential value was qualified and no adjustment was made, thus obtaining the core-shell structure emulsion.

[0080] (5) Cool the core-shell emulsion to 25°C, filter it, and obtain a fluorine-free waterproofing agent; take a sample and measure the centrifugal precipitation rate of 0.9%, and determine that the amount of γ-aminopropyltriethoxysilane added in the next batch should remain unchanged at 8.0g. Example

[0081] (1) 100g of octadecyl methacrylate, 3g of acrylic acid and 2g of allyloxynonylphenol polyoxyethylene ether ammonium sulfate were mixed with 80g of deionized water at 300 r / min to obtain a preliminary mixed system; the preliminary mixed system was pre-emulsified at 800 r / min and 45℃ for 45 min; at the 20th minute, a sample was taken and the solid content was measured to be 52%. Based on its higher than 50%, 7.4g of deionized water was added to the system and the treatment continued until the end of the total time to obtain a qualified pre-emulsion.

[0082] (2) Take 60g of the qualified pre-emulsion and add it to a four-necked flask; heat it to 80℃ under argon protection, take 20g of 5% ammonium persulfate aqueous solution, add 5g of 5% ammonium persulfate aqueous solution to the four-necked flask at one time, and at the same time start to add the remaining 15g of ammonium persulfate aqueous solution at a rate of 0.5 mL / min. The total reaction time is 60min; take a sample at 30min and measure the average particle size as 62nm. Based on the fact that it is lower than 65nm, increase the initiator dropping rate from 0.09 mL / min to 0.59 mL / min to obtain a qualified seed emulsion.

[0083] (3) Maintain all the seed emulsions at 80℃ and 400 r / min; take 13g of 5% ammonium persulfate aqueous solution and add 3.5g of 5% ammonium persulfate aqueous solution as the initial initiator to the system; mix 40g of the remaining pre-emulsion from step S1 with 7g of the ammonium persulfate aqueous solution and add it dropwise at a rate of 1.0 mL / min, which is completed within 50 min; set aside 2.5g of the ammonium persulfate aqueous solution; when the dropwise addition is completed and the reaction has proceeded to 70 min, the monomer conversion rate is measured to be 98.5%, and no adjustment is made to obtain a qualified core layer emulsion.

[0084] (4) Add 8g of γ-aminopropyltriethoxysilane to all qualified core emulsions and react at 400 r / min for 10 min; add 5g of tetraethyl orthosilicate and continue stirring for 10 min; increase the speed to 500 r / min and add 10% ammonia water at a rate of 1.0 mL / min to precisely adjust the initial pH of the reaction system to 9.5, and carry out in-situ sol-gel reaction at 65℃ for a total time of 240 min; take a sample at 60 min and measure the absolute value of the Zeta potential to be 30mV, without adjustment, to obtain the core-shell structure emulsion.

[0085] (5) Cool the core-shell emulsion to 25°C, filter it using a 500-mesh filter cloth, and collect the filtrate to obtain the fluorine-free waterproofing agent; the centrifugal sedimentation rate was measured to be 0.6%, and based on its being less than 0.7%, the amount of γ-aminopropyltriethoxysilane added in the next batch was determined to be reduced by 0.05g to 7.95g from 8.0g.

[0086] Performance testing The fluorine-free waterproofing agents prepared in Examples 1-3 were formulated into a 50 g / L working solution, and pure cotton fabrics were impregnated and padded. The fabrics were then baked at 120°C for 3 min, and their properties were tested as shown in Table 1 below. Table 1: Performance Comparison of Fluorine-Free Waterproofing Agents

[0087] Comparative Example 1 is a traditional acrylic waterproofing agent; Initial contact angle 145°, contact angle 125° after 20 washes, hand feel rating 3.2; Comparative Example 2 is an organosilicon waterproofing agent: Initial contact angle 142°, contact angle 128° after 20 washes, feel rating 4.0.

[0088] Test results show that the fluorine-free waterproofing agent prepared by this invention is significantly superior to the comparative example in terms of initial waterproofing, washability, and hand feel.

[0089] In this embodiment of the invention, the hand feel score is comprehensively evaluated by five trained reviewers based on the fabric's softness and smoothness. A score of 1 indicates stiffness and roughness, while a score of 5 indicates softness and smoothness.

[0090] Specifically, this invention successfully prepared a fluorine-free waterproofing agent with a "polymer core-organic-inorganic hybrid shell" structure through a multi-step synergistic process of "pre-emulsification-seed polymerization-core layer polymerization-in-situ hybridization" and closed-loop quality control throughout the entire process. The fluorine-free waterproofing agent obtained by the preparation method shown in Examples 1-3 was formulated into a 50g / L working solution. After treating pure cotton fabrics, the initial contact angle was as high as 148° or more, and the contact angle remained above 139° after 20 washes. At the same time, the hand feel score reached 4.2 points or more, which comprehensively surpassed the performance of traditional acrylic and silicone waterproofing agents. Under completely fluorine-free conditions, it solved the industry technical bottleneck of the difficulty in achieving high waterproofness, high wash resistance and excellent hand feel at the same time.

[0091] The technical solution of the present invention has been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the scope of protection of the present invention.

Claims

1. A method for preparing a fluorine-free waterproofing agent, characterized in that, include, 100g of octadecyl methacrylate, 3g of acrylic acid, and 2g of allyloxynonylphenol polyoxyethylene ether ammonium sulfate were mixed with 80g of deionized water and pre-emulsified to obtain a pre-emulsion. The amount of material added during the pre-emulsification process is dynamically adjusted based on the solid content of the pre-emulsified liquid. Add 60g of the pre-emulsion and 20g of 5% ammonium persulfate aqueous solution to the reactor, heat the reaction system to the polymerization reaction temperature, and carry out seed emulsion polymerization to obtain seed emulsion; The dropping rate of the ammonium persulfate aqueous solution is dynamically adjusted during the polymerization process based on the average particle size of the particles in the seed emulsion. The remaining pre-emulsion and 13g of 5% ammonium persulfate aqueous solution were added dropwise to the seed emulsion at a uniform rate to carry out a core-layer polymerization reaction and obtain a core-layer emulsion. The amount of ammonium persulfate added is dynamically adjusted based on the monomer conversion rate of the core emulsion during the reaction process. 8g of γ-aminopropyltriethoxysilane and 5g of tetraethyl orthosilicate were added to the core layer emulsion. The pH of the reaction system was adjusted to the initial pH value with 10% ammonia water. An in-situ sol-gel reaction was carried out, and the reaction occurred on the surface of the polymer particles of the core layer emulsion to form a core-shell structure emulsion with an organic-inorganic hybrid shell. The dropping rate of the ammonia solution is dynamically adjusted based on the absolute value of the Zeta potential of the core-shell emulsion. The core-shell emulsion was cooled to room temperature, filtered, and collected to obtain the fluorine-free waterproofing agent. The amount of γ-aminopropyltriethoxysilane added in the next batch is determined based on the centrifugal sedimentation rate of the fluorine-free waterproofing agent obtained in the current batch.

2. The preparation method of the fluorine-free waterproofing agent according to claim 1, characterized in that, The process of determining and dynamically adjusting the amount of material added during the pre-emulsification process based on the solid content of the pre-emulsified liquid includes the following steps: 100g of octadecyl methacrylate, 3g of acrylic acid, and 2g of allyloxynonylphenol polyoxyethylene ether ammonium sulfate were slowly mixed with 80g of deionized water at 300r / min to obtain the first mixed solution. The first mixed solution was placed in an emulsification reactor and stirred at 800 r / min and emulsification temperature of 45℃ for 45 min for pre-emulsification treatment. When the pre-emulsification process reaches the 20th minute, a small amount of pre-emulsified liquid sample is taken and the solid content is obtained; The solid content is compared with a preset solid content range; Based on the fact that the solid content is lower than the lower limit of the preset solid content range, the acrylic acid and the allyloxynonylphenol polyoxyethylene ether ammonium sulfate are added to the pre-emulsification treatment by multiplying the absolute difference between the solid content and the lower limit of the preset solid content range by the original mass ratio before the addition.

3. The preparation method of the fluorine-free waterproofing agent according to claim 2, characterized in that, The process of determining and dynamically adjusting the amount of material added during the pre-emulsification process based on the solid content of the pre-emulsified liquid also includes... Based on the fact that the solid content is higher than the upper limit of the preset solid content range, it is determined that 2% of the total mass of the system of deionized water will be added, which is the absolute difference between the solid content and the upper limit of the preset solid content range.

4. The preparation method of the fluorine-free waterproofing agent according to claim 3, characterized in that, The process of determining the dropping rate of the ammonium persulfate aqueous solution during polymerization based on the average particle size in the seed emulsion includes, The reaction system was heated to the polymerization reaction temperature of 80°C at a heating rate of 5°C / min under an argon atmosphere. Add 5g of the ammonium persulfate aqueous solution to the reactor at a stirring speed of 400r / min in one go; The remaining 15g of the ammonium persulfate aqueous solution was transferred to a constant pressure dropping funnel and added dropwise to the reactor at a first initial dropping rate of 0.5ml / min for a total reaction time of 60min. A small amount of emulsion sample was taken from the reaction system and cooled to room temperature at 30 min of reaction time. Obtain the average particle size of the particles in the emulsion sample; The average particle size is compared with a preset average particle size range; Based on the fact that the average particle size is lower than the preset lower limit of the average particle size, the dropping acceleration rate is increased by multiplying the absolute difference between the average particle size and the preset lower limit of the average particle size range by 0.03 ml / min, based on the first initial dropping acceleration rate.

5. The preparation method of the fluorine-free waterproofing agent according to claim 4, characterized in that, The process of determining the dropping rate of the ammonium persulfate aqueous solution during polymerization based on the average particle size in the seed emulsion also includes, Based on the fact that the average particle size is higher than the preset upper limit of the average particle size, the dropping acceleration rate is determined to be reduced by multiplying the absolute difference between the average particle size and the upper limit of the preset average particle size range by 0.02 ml / min, based on the first initial dropping acceleration rate.

6. The preparation method of the fluorine-free waterproofing agent according to claim 5, characterized in that, The process of dynamically adjusting the amount of ammonium persulfate aqueous solution added based on the monomer conversion rate of the core emulsion during the reaction process includes, Take 40g of the pre-emulsion and 13g of ammonium persulfate aqueous solution; 40g of the pre-emulsion was transferred to a constant pressure dropping funnel and 7g of the ammonium persulfate aqueous solution was added at once to obtain a second mixed solution; All of the seed emulsions were transferred to a four-necked flask reactor and maintained at 80°C and 400 r / min. 3.5 g of the ammonium persulfate aqueous solution was added at once, and the second mixed solution was added dropwise to the four-necked flask reactor at a second initial drop rate of 1.0 ml / min. The total reaction time was 90 min. The remaining 2.5g of the ammonium persulfate aqueous solution was used as a backup solution; After all the second mixed solution has been added and the reaction has proceeded for 70 minutes, a small amount of core emulsion sample is taken from the reaction system and the monomer conversion rate is obtained. The monomer conversion rate is compared with the preset monomer conversion rate; Based on the fact that the monomer conversion rate is less than the preset monomer conversion rate, the absolute difference between the monomer conversion rate and the preset monomer conversion rate is multiplied by 20% of the spare solution and added to the reaction system at once as the supplementary amount.

7. The preparation method of the fluorine-free waterproofing agent according to claim 6, characterized in that, The process of determining the dynamic adjustment rate of ammonia droplets based on the absolute value of the Zeta potential of the core-shell emulsion includes, 8g of γ-aminopropyltriethoxysilane was added to the core emulsion at once and stirred at 400r / min for 10min to obtain a third mixed solution; Add 5g of tetraethyl orthosilicate to the third mixed solution at once and stir at 400r / min for 10min to obtain the fourth mixed solution; The ammonia solution was added dropwise to the fourth mixed solution at a third initial dropping rate of 1.0 ml / min at a speed of 500 r / min, and the in-situ sol-gel reaction was initiated at 65°C. The total reaction time was 240 min. When the in-situ sol-gel reaction was carried out for 60 minutes, a small amount of core-shell emulsion sample was taken out from the reaction system and the absolute value of the Zeta potential was obtained. The absolute value of the Zeta potential is compared with a preset range of absolute potential values; Based on the fact that the absolute value of the Zeta potential is lower than the lower limit of the preset absolute value range, the drip acceleration rate is increased by multiplying the absolute difference between the absolute value of the Zeta potential and the lower limit of the preset absolute value range by 0.05 ml / min, based on the current drip acceleration rate.

8. The preparation method of the fluorine-free waterproofing agent according to claim 7, characterized in that, The process of determining the dynamic adjustment rate of ammonia droplets based on the absolute value of the Zeta potential of the core-shell emulsion also includes, Based on the fact that the absolute value of the Zeta potential is higher than the upper limit of the preset absolute value range, the drip acceleration rate is determined to be reduced by multiplying the absolute difference between the absolute value of the Zeta potential and the upper limit of the preset absolute value range by 0.02 ml / min, based on the current drip acceleration rate.

9. The preparation method of the fluorine-free waterproofing agent according to claim 8, characterized in that, The process of determining the amount of γ-aminopropyltriethoxysilane to be added in the next batch based on the centrifugal sedimentation rate of the fluorine-free waterproofing agent obtained in the current batch includes, The core-shell emulsion was cooled to 25°C; The fluorine-free waterproofing agent is obtained by filtering through a 500-mesh filter cloth and collecting the filtrate. The fluorine-free waterproofing agent was sampled and the centrifugal sedimentation rate was obtained; The centrifugal sedimentation rate is compared with a preset centrifugal sedimentation rate range; Based on the fact that the centrifugal sedimentation rate is lower than the lower limit of the preset centrifugal sedimentation rate range, the absolute difference between the centrifugal sedimentation rate and the preset lower limit of the centrifugal sedimentation rate is multiplied by 0.05g as the reduction amount of the next batch of γ-aminopropyltriethoxysilane.

10. The preparation method of the fluorine-free waterproofing agent according to claim 9, characterized in that, The process of determining the amount of γ-aminopropyltriethoxysilane to be added in the next batch based on the centrifugal sedimentation rate of the fluorine-free waterproofing agent obtained in the current batch also includes, Based on the fact that the centrifugal sedimentation rate is higher than the upper limit of the preset centrifugal sedimentation rate range, the absolute difference between the centrifugal sedimentation rate and the upper limit of the preset centrifugal sedimentation rate range is multiplied by 0.1g as the increase amount of the γ-aminopropyltriethoxysilane in the next batch.

Images