Water-soluble polyvinyl butyral emulsion and preparation method thereof

Abstract

The invention relates to the technical field of high polymer materials, and particularly discloses a water-soluble polyvinyl butyral emulsion and a preparation method thereof.The preparation method comprises the following preparation steps that dissolving is conducted, PVB and ethyl alcohol are dissolved, the dissolving temperature ranges from 50 DEG C to 60 DEG C, the dissolving time ranges from 1 h to 3 h, and a dissolving solution is obtained; base catalytic emulsification: sequentially adding a composite plasticizer and a composite emulsifier into the obtained dissolved solution, stirring and mixing, then slowly dropwise adding alkali liquor into a reaction system, and reacting for 0.2-0.8 hour to obtain primary emulsion; shearing and emulsifying: adding the acrylate core-shell emulsion into the obtained primary emulsion, and then carrying out high-speed shearing and emulsifying to obtain a composite emulsion; and adding a compound thickening agent into the obtained composite emulsion, and stirring for at least 20 minutes to obtain the network-shaped water-soluble polyvinyl butyral emulsion.

Description

Technical Field

[0001] This invention relates to the field of polymer materials, specifically to a water-soluble polyvinyl butyral emulsion and its preparation method. Background Technology

[0002] Water-soluble polyvinyl butyral (PVB) emulsion is an environmentally friendly polymer material. By modifying polyvinyl butyral to achieve water dispersibility, dependence on organic solvents is reduced. Preparation typically involves two methods: chemical modification and emulsification dispersion, as detailed below: Chemical modification: Introducing hydrophilic groups, such as carboxyl groups, into polyvinyl butyral molecules improves their water solubility. For example, adding glyoxylic acid during the acetalization reaction gives PVB molecules carboxyl groups, enhancing their emulsifying properties.

[0003] Emulsification dispersion method: Using anionic or nonionic surfactants, such as sodium dodecyl sulfonate and OP-10, PVB resin is dispersed in water to form a stable emulsion.

[0004] However, traditional preparation methods often suffer from solvent residues that compromise environmental performance. Traditional PVB emulsions require alcohols or esters as solvents, with alcohol content reaching as high as 85%. These organic solvents evaporate during printing, impacting the production environment and operator health. Other methods use more than 10% organic solvents, such as ethanol, whose residual solvents affect food-grade safety. Some processes also use toxic chemicals like phthalic anhydride and acetone, posing toxicity issues. Furthermore, the complexity of the process, the need for precise temperature and ratio control during grafting modification, and poor industrial stability all contribute to problems. Additionally, low emulsification efficiency, high energy consumption for conventional mechanical homogenization, and a high risk of emulsion phase inversion failure also exist.

[0005] Chinese invention patent CN201410005903.9 describes an environmentally friendly water-soluble PVB emulsion production process. This invention involves the preparation of PVB resin, PVB resin production, addition of emulsifiers, addition of grafting solution and grafting catalyst, and grafting at a specific temperature to produce water-soluble PVB resin. Finally, water is added to adjust the PVB emulsion to a solid content of 10%, 20%, or 30% according to different requirements. Compared with existing technologies, the alcohol content of the PVB emulsion produced by this invention is reduced from 85% in alcohol-soluble PVB resin to 10%, further improving its environmental performance. The adhesion meets the requirements for cotton, wood, metal, glass, and plastic substrates; the film strength reaches 5H; and it can remain undivided for more than 90 days after production. Most importantly, the PVB emulsion produced by this invention has no chemical toxicity, and the residues meet the standards for food-grade inks and cigarette packaging inks.

[0006] Although the patent reduces the amount of solvent used, the acetalization reaction conditions are harsh and require multiple purification steps; although the alcohol solvent content is reduced to 10%, the residual content may still affect the safety of food-grade applications. Summary of the Invention

[0007] In order to overcome the above-mentioned technical problems in the prior art, the present invention provides a method for preparing water-soluble polyvinyl butyral emulsion, which has low solvent residue, high stability, and controllable cost; and strong adhesion to metals, glass, wood, plastics and other materials.

[0008] To achieve the above objectives, embodiments of the present invention provide a method for preparing a water-soluble polyvinyl butyral emulsion, comprising the following preparation steps: Dissolution: Dissolve PVB in ethanol at a temperature of 50-60℃ for 1-3 hours to obtain a solution; Alkali-catalyzed emulsification: Add composite plasticizer and composite emulsifier sequentially to the obtained solution, stir and mix, then slowly add alkali solution dropwise to the reaction system, and react for 0.2-0.8 hours to obtain the primary emulsion; Shear emulsification: Add acrylate core-shell emulsion to the obtained primary emulsion, and then perform high-speed shear emulsification to obtain a composite emulsion; Add a compound thickener to the obtained composite emulsion and stir for at least 20 minutes to obtain a water-soluble polyvinyl butyral emulsion with a network structure. The composite plasticizer includes triethylene glycol diisooctanoate, tributyl acetyl citrate, and methyl epoxyacetyl linoleate. The composite emulsifier includes fatty alcohol polyoxyethylene ether, alkyl polyglucoside and sulfosuccinate; The compound thickener includes a hydrophobically modified alkali-swellable thickener and a hydrophobically modified polyurethane thickener.

[0009] Preferably, the mass ratio of triethylene glycol diisooctanoate, acetylated tributyl citrate, and epoxy acetylated linoleate methyl ester is 8:1.5:0.5; The steps for adding the composite plasticizer are as follows: first, add triethylene glycol diisooctanoate to the reaction system and stir for 5-10 minutes; then add acetylacetic acid tributyl ester to the reaction system and stir for 5-10 minutes; finally, add epoxy acetylacetic acid methyl ester to the reaction system and stir for 15-20 minutes.

[0010] Preferably, the mass ratio of the fatty alcohol polyoxyethylene ether, alkyl polyglucoside, and sulfosuccinate is 5:3:2. The fatty alcohol polyoxyethylene ether, alkyl polyglucoside, and sulfosuccinate are mixed according to the mass ratio and then added to the reaction system. The mixture is stirred at 50-60°C for 0.5-1 hour.

[0011] Preferably, the specific operation steps of the alkali-catalyzed emulsification are as follows: Add the composite plasticizer to the obtained solution and stir evenly. While maintaining the temperature at 50-60℃, add the composite emulsifier and stir for 0.5-1 hour. During the reaction, slowly add hot alkaline solution at 55℃ to the reaction system and stir the reaction for 0.5-1 hour to obtain the primary emulsion.

[0012] Preferably, the shear emulsification step is as follows: The obtained primary emulsion was slowly added dropwise with an acrylate core-shell emulsion of 1-3% at a stirring speed of 800-1000 rpm, and the reaction was continued for 5-10 minutes. Then the stirring speed was increased to 2500-3200 rpm and the temperature was 50-55℃ for emulsification for 3-4 hours to obtain a composite emulsion.

[0013] Preferably, the hydrophobic modified alkali-swellable thickener is dissolved in 5-10 times the amount of deionized water for dilution to obtain an aqueous solution of the hydrophobic modified alkali-swellable thickener; A hydrophobic modified polyurethane thickener is dissolved in a mixed solvent to obtain an aqueous solution of the hydrophobic modified polyurethane thickener, wherein the mixed solvent is deionized water and ethylene glycol; At a temperature of 50-60°C and a rotation speed of 800-1000 rpm, slowly add an aqueous solution of hydrophobic modified alkali-swelling thickener and react for 15-20 minutes. Next, lower the temperature of the reaction system to 30-35℃, rotate the spindle at 400-500 rpm, slowly add the hydrophobic modified polyurethane thickener aqueous solution, and stir for 15-20 minutes. After the reaction is complete, let it stand for 3-15 hours.

[0014] A water-soluble polyvinyl butyral emulsion is prepared by the above method.

[0015] Preferably, it comprises the following components, in parts by weight: 80-120 parts PVA; 200-220 parts ethanol; 15-25 parts compound plasticizer; 15-25 parts compound emulsifier; 180-220 parts alkali solution; 5-15 parts acrylate core-shell emulsion; 2-8 parts compound thickener; The composite plasticizer includes triethylene glycol diisooctanoate, tributyl acetyl citrate, and methyl epoxyacetyl linoleate. The composite emulsifier includes fatty alcohol polyoxyethylene ether, alkyl polyglucoside and sulfosuccinate; The compound thickener includes a hydrophobic modified alkali-swellable thickener and a hydrophobic modified polyurethane thickener; Ethanol is evaporated, condensed, and recovered.

[0016] Preferably, it comprises the following components, in parts by weight: 100 parts PVA; 220 parts ethanol; 20 parts compound plasticizer; 20 parts compound emulsifier; 200 parts alkali solution; 10 parts acrylate core-shell emulsion; 5 parts compound thickener; The composite plasticizer includes triethylene glycol diisooctanoate, tributyl acetyl citrate, and methyl epoxyacetyl linoleate. The composite emulsifier includes fatty alcohol polyoxyethylene ether, alkyl polyglucoside and sulfosuccinate; The compound thickener includes a hydrophobic modified alkali-swellable thickener and a hydrophobic modified polyurethane thickener; Ethanol is evaporated, condensed, and recovered.

[0017] This invention also provides an application of water-soluble polyvinyl butyral emulsion in the fields of metals, glass, wood, and plastics.

[0018] This invention also provides an application of water-soluble polyvinyl butyral emulsion in the fields of metals, glass, wood, and plastics.

[0019] The technical solution provided by this invention has at least the following technical effects: In the process of preparing water-soluble polyvinyl butyral emulsion, a composite plasticizer, a composite emulsifier, an acrylate core-shell emulsion, and a compound thickener are added. By using the composite plasticizer to provide the basic emulsification conditions for the composite emulsifier, the composite emulsifier can provide stable emulsion particles in combination with the compound thickener. The acrylate core-shell emulsion can lock the compound thickener and the emulsified PVB together, thereby making the prepared emulsion more physically stable. By setting the compound thickener, the PVB molecular chains in the reaction system are more flexible and have better molding properties, while also preventing brittleness and exhibiting strong water resistance and stability. In addition, ethanol can be distilled and recovered during the preparation process, resulting in extremely low solvent residue, which will not harm health or the environment.

[0020] Other features and advantages of the embodiments of the present invention will be described in detail in the following detailed description section. Detailed Implementation

[0021] The following detailed description, in conjunction with specific embodiments of the present invention, is provided. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the present invention.

[0022] In this embodiment of the invention, the term "multiple" refers to two or more. Therefore, in this embodiment, "multiple" can also be understood as "at least two." "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone. Additionally, the character " / ", unless otherwise specified, generally indicates that the preceding and following related objects have an "or" relationship. Furthermore, it should be understood that in the description of this embodiment of the invention, terms such as "first" and "second" are used only for descriptive purposes and should not be construed as indicating or implying relative importance or order.

[0023] In existing technologies, the preparation of water-soluble polyvinyl butyral emulsions typically employs chemical modification and emulsification dispersion methods. Both of these methods use alcohols as solvents and toxic chemicals such as phthalic anhydride and acetone, resulting in toxic residues. In addition, the acetalization conditions are harsh and difficult to operate, while also exhibiting low emulsification efficiency, high energy consumption, and poor water resistance, stability, and adhesion of the resulting polyvinyl butyral emulsion.

[0024] Given the aforementioned prior art, it is necessary to provide a method for preparing a water-soluble polyvinyl butyral emulsion, which features low solvent content, high stability, and ease of operation, and includes the following preparation steps: Dissolution: Dissolve PVB in ethanol at a temperature of 50-60℃ for 1-3 hours to obtain a solution; Alkali-catalyzed emulsification: Add composite plasticizer and composite emulsifier sequentially to the obtained solution, stir and mix, then slowly add alkali solution to the reaction system, react for 0.2-0.8 hours to obtain primary emulsion; Shear emulsification: Add acrylate core-shell emulsion to the obtained primary emulsion, and then perform high-speed shear emulsification to obtain a composite emulsion; Add a compound thickener to the obtained composite emulsion and stir for at least 20 minutes to obtain a water-soluble polyvinyl butyral emulsion with a network structure; the compound plasticizer includes triethylene glycol diisooctanoate, tributyl acetyl citrate and methyl epoxyacetyl linoleate. The composite emulsifier includes fatty alcohol polyoxyethylene ether, alkyl polyglucoside and sulfosuccinate; The compound thickener includes a hydrophobically modified alkali-swellable thickener and a hydrophobically modified polyurethane thickener.

[0025] This invention provides a water-soluble polyvinyl butyral emulsion, mainly comprising the steps of dissolution, alkali-catalyzed emulsification, shear emulsification, and obtaining the water-soluble polyvinyl butyral emulsion. In one possible embodiment, the water-soluble polyvinyl butyral emulsion is prepared by first dissolving PVB resin in ethanol at a temperature of 50-60°C for 1-3 hours to obtain a solution. The PVB resin used in this invention is SDL-28B, a low-viscosity PVB resin produced by Longcheng Company. The viscosity range of the low-viscosity SDL-28B resin is 9-14 mPa·s, which is the rotational viscosity of 10 parts of resin dissolved in 90 parts of ethanol. The rotational viscosity of ethanol with 10% solids content is 12 mPa·s.

[0026] A composite plasticizer and a composite emulsifier are added sequentially to the obtained solution. The composite plasticizer inserts into the spaces between the PVB macromolecular chains to weaken their interaction forces, making the PVB molecular chains looser and more flexible. This provides effective adsorption conditions for the subsequent addition of the composite emulsifier, making the emulsifier easier to penetrate. Under the above conditions, the composite emulsifier is added, allowing it to arrange itself in the reaction system to form an oil-in-water (O / W) emulsion, thus forming a protective layer. Then, an alkaline solution is added for emulsification. After emulsification, an acrylate core-shell emulsion is added to the reaction system. This acrylate core-shell emulsion can disperse between the emulsion particles in the reaction system, acting as a physical barrier to prevent sedimentation. Finally, a thickener is added. The hydrophobic end of the thickener can anchor on the surface of the PVB and core-shell particles, and the hydrophilic chains extend and entangle in the water, forming a three-dimensional network structure like a fishing net, locking the particles within this three-dimensional network structure. By using plasticizers to provide the basic emulsification conditions for emulsifiers, the emulsifiers can provide stable emulsion particles for the thickeners. The acrylate core-shell emulsion can lock the thickeners and emulsified PVB together, thereby making the prepared emulsion more physically stable. The composite plasticizers used in this invention include triethylene glycol diisooctanoate, tributyl acetylacetonate, and methyl epoxyacetylacetic acid. The composite emulsifiers include fatty alcohol polyoxyethylene ether, alkyl polyglucoside, and sulfosuccinate. The compound thickeners include hydrophobically modified alkali-swelling thickeners and hydrophobically modified polyurethane thickeners. The above components can work synergistically to complement each other, thereby making the prepared water-soluble polyvinyl butyral emulsion uniformly emulsified and dispersed, and with strong stability.

[0027] The choice of composite plasticizer components has a significant impact on the interaction forces of PVB molecular chains in the solution. If the composite plasticizer is not chosen properly, it cannot effectively insert into the spaces between PVB molecular chains, cannot make the PVB molecular chains more flexible, and therefore cannot better cooperate with the emulsifier, thus failing to achieve the purpose of weakening the intermolecular forces.

[0028] In this embodiment of the invention, the composite plasticizer comprises triethylene glycol diisooctanoate, acetylated tributyl citrate, and epoxy acetylated linoleate methyl ester, wherein the mass ratio of triethylene glycol diisooctanoate, acetylated tributyl citrate, and epoxy acetylated linoleate methyl ester is 8:1.5:0.5. The steps for adding the composite plasticizer are as follows: first, add triethylene glycol diisooctanoate to the reaction system and stir for 5-10 minutes; then add acetylacetic acid tributyl ester to the reaction system and stir for 5-10 minutes; finally, add epoxy acetylacetic acid methyl ester to the reaction system and stir for 15-20 minutes.

[0029] In one possible embodiment, the composite plasticizer includes triethylene glycol diisooctanoate, tributyl acetylacetonate, and methyl epoxide acetylacetonate. Triethylene glycol diisooctanoate serves as the main plasticizer and is added to the reaction system first for a reaction of 5-10 minutes. This allows triethylene glycol diisooctanoate to fully interact with the PVB molecular chains, establishing a foundation for flexibility. Its good compatibility enables rapid and uniform dispersion. After the reaction, tributyl acetylacetonate is added to the system and reacted for another 5-10 minutes. The main plasticizer has already initially "opened up" the PVB chain structure, making it easier for tributyl acetylacetonate to penetrate and disperse. This synergistic effect enhances its overall performance. Finally, methyl epoxide acetylacetonate is added to the system and the reaction continues for 15-20 minutes. The synergistic effect of the three plasticizers ensures thorough mixing and uniform distribution of the PVB system, achieving a swelling equilibrium state and providing favorable conditions for emulsification, thus promoting and optimizing the final emulsification effect.

[0030] In the combination of three plasticizers, the mass ratio of triethylene glycol diisooctanoate, acetylated tributyl citrate, and epoxy acetylated linoleate methyl ester is 8:1.5:0.5, which is the optimal dosage. Triethylene glycol diisooctanoate is the main plasticizer, capable of undertaking core and efficient plasticization. Acetyl citrate mainly plays an auxiliary and reinforcing role, significantly enhancing plasticizing performance while being non-toxic and environmentally friendly. At this dosage, epoxy acetylated linoleate methyl ester effectively provides oxidation and thermal stability, improves low-temperature performance, avoids potential crystallization problems, and does not put excessive pressure on costs. In addition, the epoxy groups in the epoxy acetylated linoleate methyl ester molecule can also act as primary antioxidants, absorbing peroxides or free radicals that may be present in the system, improving the thermal stability of the emulsion, and preventing viscosity changes or yellowing due to oxidation during production and storage. It is an essential component.

[0031] The selection of components in a composite emulsifier plays a crucial role in the emulsification efficiency. An inappropriate selection can lead to wasted costs and failure in the preparation of water-soluble polyvinyl butyral emulsions.

[0032] In this embodiment of the invention, the composite emulsifier includes fatty alcohol polyoxyethylene ether, alkyl polyglucoside and sulfosuccinate, wherein the mass ratio of fatty alcohol polyoxyethylene ether, alkyl polyglucoside and sulfosuccinate is 5:3:2. The fatty alcohol polyoxyethylene ether, alkyl polyglucoside and sulfosuccinate are added to the reaction system according to the mass ratio, and the mixture is stirred for 0.5-1 hour at a temperature of 50-60°C.

[0033] In one possible embodiment, the composite emulsifier includes fatty alcohol polyoxyethylene ether, alkyl polyglucoside, and sulfosuccinate. The fatty alcohol polyoxyethylene ether provides reliable steric hindrance protection, which is the fundamental guarantee for system stability. The alkyl polyglucoside is 100% bio-based, non-toxic, non-irritating, and completely biodegradable. This substance has strong alkali resistance and has a synergistic effect with the fatty alcohol polyoxyethylene ether. The sulfosuccinate is a stabilizing agent that can provide an electrostatic barrier for the system, forming a "steric-electrostatic" dual protection with the first two nonionic emulsifiers, thereby maximizing the stability of the emulsion.

[0034] Using these three substances as a composite emulsifier can provide steric hindrance, biocompatibility, and electrostatic repulsion, thereby maximizing the stability of the emulsion.

[0035] By using a mass ratio of fatty alcohol polyoxyethylene ether, alkyl polyglucoside, and sulfosuccinate of 5:3:2, the system can be better integrated, resulting in better emulsification efficiency, stability, cost, and environmental friendliness.

[0036] By incorporating a composite plasticizer, which primarily functions within the PVB particles to weaken intermolecular forces, the emulsifier can provide protection on the particle surface, specifically by offering space and charge protection. Furthermore, the combination of the composite plasticizer and the composite emulsifier can synergistically lower the glass transition temperature. Specifically, the composite plasticizer lowers the glass transition temperature of PVB from within, while the emulsifier improves interfacial compatibility. Together, they enable PVB particles to maintain good deformation capacity at lower temperatures, which is crucial for the density and performance of the subsequent film formation.

[0037] Pre-emulsification is a crucial step in the preparation of aqueous polyvinyl butyral emulsions. Without pre-emulsification, the stability of the product will decrease, and uneven particle size distribution of the emulsion will occur.

[0038] In this embodiment of the invention, the specific operation steps of the alkali-catalyzed emulsification are as follows: Add plasticizer to the obtained solution and stir evenly. While maintaining the temperature at 50-60℃, add composite emulsifier and stir for 0.5-1 hour. During the reaction, continue stirring and slowly add hot alkaline solution at 55℃ to the reaction system. Continue the reaction for 0.5-1 hour to form a primary emulsion.

[0039] In one possible embodiment, this application first achieves "internal plasticization" by allowing the composite plasticizer to fully interact with PVB molecules, laying the foundation for subsequent "interfacial emulsification" and avoiding competition between the plasticizer and emulsifier, which could affect the final product performance. The composite emulsifier is added at a temperature of 50-60°C and reacted for 0.5-1 hour, providing sufficient time for the emulsifier molecules to diffuse, distribute, and anchor in the oil phase. Maintaining a constant temperature ensures system stability and prevents temperature fluctuations from affecting the emulsifier's solubility. A hot alkaline solution is then added to the reaction system. This alkaline solution reduces the system's alcohol solubility while increasing its water solubility, precisely triggering and controlling the "oil-in-water" to "water-in-oil" phase transition. By slowly adding the solution, the rate of phase transition can be controlled, allowing the emulsification process to proceed gently and preventing excessively vigorous reactions that could lead to coarse emulsion particles or demulsification. This results in a primary emulsion with extremely high stability and more uniform particle size.

[0040] In existing technologies, the anti-settling and storage stability of products using emulsification processes do not meet satisfactory requirements.

[0041] In this embodiment of the invention, the shear emulsification step is as follows: The obtained primary emulsion was slowly added dropwise with an acrylate core-shell emulsion of 1-3% at a stirring speed of 800-1000 rpm, and the reaction was continued for 5-10 minutes. Then the stirring speed was increased to 2500-3200 rpm and the temperature was 50-55℃ for emulsification for 3-4 hours to obtain a composite emulsion.

[0042] In one possible embodiment, 1-3% acrylate core-shell emulsion is slowly added dropwise at 800-1000 rpm. This gently disperses the core-shell emulsion into the PVB primary emulsion, ensuring the integrity of its particle structure. High-speed shearing at 2500-3200 rpm is then applied. Even under this high-shear condition, the structure of the core-shell emulsion will not be damaged. The main purpose is to refine the PVB emulsion particles. If a high-concentration core-shell emulsion is directly poured into a high-speed rotating vortex, it is prone to instantaneous aggregation due to excessively high local concentrations. The formation of clumps and soft particles that are difficult to disperse affects the formation of the final product. The first step is to slowly add the core-shell emulsion at a medium speed to allow it to fully combine with the primary PVB emulsion, providing good conditions for subsequent uniform dispersion. This is an important and crucial step. During the high-speed shearing stage, the refined PVB emulsion particles will be evenly distributed in the more rigid core-shell particles, resulting in physical entanglement and embedding, ultimately forming a physical composite structure. This effectively blocks the approach of PVB particles in space, greatly enhancing the storage stability, anti-settling properties, and thixotropic properties of the emulsion.

[0043] In the above preparation process, it is necessary to further enhance the chemical structure and physical properties of the aqueous polyvinyl butyral emulsion, improve its anti-settling and stability effects, and make the product more promising for market application.

[0044] In this embodiment of the invention, the compound thickener includes a hydrophobically modified alkali-swellable thickener and a hydrophobically modified polyurethane thickener. The hydrophobic modified alkali-swelling thickener was diluted with 5-10 times its volume of deionized water to obtain an aqueous solution of the hydrophobic modified alkali-swelling thickener. The hydrophobic modified polyurethane thickener was diluted in a mixed solvent prepared with 3-5 times the amount of deionized water and ethylene glycol to obtain an aqueous solution of the hydrophobic modified polyurethane thickener. At a temperature of 50-60°C and a rotation speed of 800-1000 rpm, slowly add an aqueous solution of hydrophobic modified alkali-swelling thickener and react for 15-20 minutes. Lower the temperature of the reaction system to 30-35℃, rotate the spindle speed to 400-500 rpm, slowly add the aqueous solution of hydrophobic modified polyurethane thickener, and stir for 15-20 minutes. After the reaction is complete, let it stand for 3-15 hours.

[0045] In one possible embodiment, the present invention employs a compound thickener, wherein the hydrophobic modified alkali-swellable thickener is first diluted with deionized water to completely prevent it from swelling instantly upon contact with water, ensuring that it can function uniformly. Under medium-speed stirring and heat preservation conditions, the hydrophobic modified alkali-swellable thickener is given sufficient time to allow its hydrophobic ends to be fully anchored on the surface of PVB and core-shell latex particles. Its hydrophilic chains unfold in water, intertwine with each other, and form a strong three-dimensional network structure, locking the emulsion particles inside, fundamentally solving the problems of sedimentation and stratification.

[0046] The diluted hydrophobic modified polyurethane thickener is then added at a low speed, which allows the hydrophobic modified polyurethane thickener to provide excellent leveling properties for precise adjustment and improvement, enhancing the gloss and feel of the paint film. Adding it at low temperatures also ensures product storage stability and avoids thermal degradation. Under the action of compound thickeners, they can coexist harmoniously and synergistically enhance each other, improving the product.

[0047] In the preparation of the water-soluble polyvinyl butyral emulsion described above, the formula and component content are unclear, which can easily lead to failure in the preparation process.

[0048] In this embodiment of the invention, the following components are included, in parts by weight: 80-120 parts PVA; 200-220 parts ethanol; 15-25 parts compound plasticizer; 15-25 parts compound emulsifier; 180-220 parts alkali solution; 5-15 parts acrylate core-shell emulsion; 2-8 parts compound thickener; The composite plasticizer includes triethylene glycol diisooctanoate, tributyl acetyl citrate, and methyl epoxyacetyl linoleate. The composite emulsifier includes fatty alcohol polyoxyethylene ether, alkyl polyglucoside and sulfosuccinate; The compound thickener includes a hydrophobic modified alkali-swellable thickener and a hydrophobic modified polyurethane thickener; Ethanol is evaporated, condensed, and recovered.

[0049] In one possible embodiment, the present invention uses low-toxicity ethanol with a recycling technology, resulting in extremely low VOCs. This formulation eliminates the use of harmful additives such as phthalates. The composite plasticizer and composite emulsifier used are relatively environmentally friendly. The composite emulsifier provides chemical stability—anti-agglomeration; the core-shell emulsion provides physical stability—anti-settling; and the compound thickener provides rheological stability—anti-stratification, thus constructing a triple stability protection system, resulting in an extremely long shelf life. The aforementioned composite plasticizer system ensures the flexibility, durability, and oxidation resistance of the paint film. Through the synergistic effect of the composite plasticizer and composite emulsifier, the prepared product has excellent adhesion. By combining it with the compound thickener, the product can have good leveling and sagging properties, thereby making the product more widely applicable.

[0050] The above formula uses a range, which is not clear or specific enough.

[0051] In this embodiment of the invention, the following components are included, in parts by weight: 100 parts PVA; 210 parts ethanol; 20 parts compound plasticizer; 20 parts compound emulsifier; 200 parts alkali solution; 10 parts acrylate core-shell emulsion; 5 parts compound thickener; The composite plasticizer includes triethylene glycol diisooctanoate, tributyl acetyl citrate, and methyl epoxyacetyl linoleate. The composite emulsifier includes fatty alcohol polyoxyethylene ether, alkyl polyglucoside and sulfosuccinate; The compound thickener includes a hydrophobic modified alkali-swellable thickener and a hydrophobic modified polyurethane thickener; Ethanol is evaporated, condensed, and recovered.

[0052] In one possible embodiment, the aqueous polyvinyl butyral emulsion obtained using the above formulation and dosage exhibits the best performance.

[0053] Ethanol evaporation-condensation recovery can be carried out using conventional equipment, and will not be elaborated on here.

[0054] Experimental Example 1 Water-soluble polyvinyl butyral emulsion, comprising the following components in parts by weight: 80 parts PVA; 200 parts ethanol; 15 parts composite plasticizer; 15 parts composite emulsifier; 180 parts alkali solution; 5 parts acrylate core-shell emulsion; and 2 parts compound thickener. The preparation steps include the following: Dissolution: Dissolve PVB in ethanol at a temperature of 50-60℃ for 1-3 hours to obtain a solution; Alkali-catalyzed emulsification: Add plasticizer to the obtained solution and stir evenly. While maintaining the temperature at 50-60℃, add composite emulsifier and stir for 0.5-1 hour. During the reaction, slowly add hot alkaline solution at 55℃ to the reaction system and stir the reaction for 0.5-1 hour to obtain primary emulsion.

[0055] The composite plasticizer comprises triethylene glycol diisooctanoate, acetylated tributyl citrate, and epoxy acetylated linoleate methyl ester, wherein the mass ratio of triethylene glycol diisooctanoate, acetylated tributyl citrate, and epoxy acetylated linoleate methyl ester is 8:1.5:0.5; The steps for adding the composite plasticizer are as follows: first, add triethylene glycol diisooctanoate to the reaction system and stir for 5 minutes; then, add acetylacetic acid tributyl ester to the reaction system and stir for 5 minutes; finally, add epoxy acetylacetic acid methyl ester to the reaction system and stir for 15 minutes.

[0056] The composite emulsifier comprises fatty alcohol polyoxyethylene ether, alkyl polyglucoside and sulfosuccinate, wherein the mass ratio of fatty alcohol polyoxyethylene ether, alkyl polyglucoside and sulfosuccinate is 5:3:2. The fatty alcohol polyoxyethylene ether, alkyl polyglucoside and sulfosuccinate are mixed according to the mass ratio and then added to the reaction system. The mixture is stirred at 50°C for 0.5 hours.

[0057] Shear emulsification: The obtained primary emulsion is slowly dripped into a 1% acrylate core-shell emulsion at a stirring rate of 800-1000 rpm, and the reaction is continued for 5 minutes. Then the stirring rate is increased to 2500-3200 rpm, the temperature is 50-55℃, and emulsification is carried out for 3 hours to obtain a composite emulsion.

[0058] Add a compound thickener to the obtained composite emulsion and stir for at least 20 minutes to obtain a water-soluble polyvinyl butyral emulsion with a network structure. The compound thickener includes a hydrophobically modified alkali-swellable thickener and a hydrophobically modified polyurethane thickener. The hydrophobic modified alkali-swelling thickener was diluted with 5-10 times its volume of deionized water to obtain an aqueous solution of the hydrophobic modified alkali-swelling thickener. A hydrophobic modified polyurethane thickener is dissolved in a mixed solvent to obtain an aqueous solution of the hydrophobic modified polyurethane thickener, wherein the mixed solvent is deionized water and ethylene glycol; At a temperature of 50-60°C and a rotation speed of 800-1000 rpm, slowly add an aqueous solution of hydrophobic modified alkali-swelling thickener and react for 15 minutes. Then lower the temperature of the reaction system to 30℃, rotate the speed to 400-500 rpm, slowly add the aqueous solution of hydrophobic modified polyurethane thickener, stir for 15 minutes, and let it stand for 3 hours after the reaction system is completed.

[0059] Experiment Example 2 Water-soluble polyvinyl butyral emulsion, comprising the following components in parts by weight: 120 parts PVA; 220 parts ethanol; 25 parts composite plasticizer; 25 parts composite emulsifier; 220 parts alkali solution; 15 parts acrylate core-shell emulsion; and 8 parts compound thickener. The preparation steps include the following: Dissolution: Dissolve PVB in ethanol at a temperature of 50-60℃ for 1-3 hours to obtain a solution; Alkali-catalyzed emulsification: Add plasticizer to the obtained solution and stir evenly. While maintaining the temperature at 50-60℃, add composite emulsifier and stir for 0.5-1 hour. During the reaction, slowly add hot alkaline solution at 55℃ to the reaction system and stir the reaction for 0.5-1 hour to obtain primary emulsion.

[0060] The composite plasticizer comprises triethylene glycol diisooctanoate, acetylated tributyl citrate, and epoxy acetylated linoleate methyl ester, wherein the mass ratio of triethylene glycol diisooctanoate, acetylated tributyl citrate, and epoxy acetylated linoleate methyl ester is 8:1.5:0.5; The steps for adding the composite plasticizer are as follows: first, add triethylene glycol diisooctanoate to the reaction system and stir for 5-10 minutes; then add acetylacetic acid tributyl ester to the reaction system and stir for 5-10 minutes; finally, add epoxy acetylacetic acid methyl ester to the reaction system and stir for 15-20 minutes.

[0061] The composite emulsifier comprises fatty alcohol polyoxyethylene ether, alkyl polyglucoside and sulfosuccinate, wherein the mass ratio of fatty alcohol polyoxyethylene ether, alkyl polyglucoside and sulfosuccinate is 5:3:2. The fatty alcohol polyoxyethylene ether, alkyl polyglucoside and sulfosuccinate are mixed according to the mass ratio and then added to the reaction system. The mixture is stirred at 50°C for 0.5 hours.

[0062] Shear emulsification: The obtained primary emulsion is slowly dripped into an acrylate core-shell emulsion with a concentration of 1-3% at a stirring rate of 800-1000 rpm, and the reaction is continued for 10 minutes. Then the stirring rate is increased to 2500-3200 rpm, the temperature is 50-55℃, and emulsification is carried out for 4 hours to obtain a composite emulsion.

[0063] Add a compound thickener to the obtained composite emulsion and stir for at least 20 minutes to obtain a water-soluble polyvinyl butyral emulsion with a network structure. The compound thickener includes a hydrophobically modified alkali-swellable thickener and a hydrophobically modified polyurethane thickener. The hydrophobic modified alkali-swelling thickener was diluted with 5-10 times its volume of deionized water to obtain an aqueous solution of the hydrophobic modified alkali-swelling thickener. A hydrophobic modified polyurethane thickener is dissolved in a mixed solvent to obtain an aqueous solution of the hydrophobic modified polyurethane thickener, wherein the mixed solvent is deionized water and ethylene glycol; At a temperature of 50-60°C and a rotation speed of 800-1000 rpm, slowly add an aqueous solution of hydrophobic modified alkali-swelling thickener and react for 20 minutes. Then lower the temperature of the reaction system to 30-35℃, rotate the speed to 400-500 rpm, slowly add the aqueous solution of hydrophobic modified polyurethane thickener, stir for 20 minutes, and let the reaction system stand for 15 hours after the reaction is completed.

[0064] Experimental Example 3 Water-soluble polyvinyl butyral emulsion, comprising the following components in parts by weight: 100 parts PVA; 210 parts ethanol; 20 parts composite plasticizer; 20 parts composite emulsifier; 200 parts alkali solution; 10 parts acrylate core-shell emulsion; and 5 parts compound thickener. The preparation steps include the following: Dissolution: Dissolve PVB in ethanol at a temperature of 50-60℃ for 1-3 hours to obtain a solution; Alkali-catalyzed emulsification: Add plasticizer to the obtained solution and stir evenly. While maintaining the temperature at 50-60℃, add composite emulsifier and stir for 0.5-1 hour. During the reaction, slowly add hot alkaline solution at 55℃ to the reaction system and stir the reaction for 0.5-1 hour to obtain primary emulsion.

[0065] The composite plasticizer comprises triethylene glycol diisooctanoate, acetylated tributyl citrate, and epoxy acetylated linoleate methyl ester, wherein the mass ratio of triethylene glycol diisooctanoate, acetylated tributyl citrate, and epoxy acetylated linoleate methyl ester is 8:1.5:0.5; The steps for adding the composite plasticizer are as follows: first, add triethylene glycol diisooctanoate to the reaction system and stir for 8 minutes; then add acetylacetic acid tributyl ester to the reaction system and stir for 8 minutes; finally, add epoxy acetylacetic acid methyl ester to the reaction system and stir for 18 minutes.

[0066] The composite emulsifier comprises fatty alcohol polyoxyethylene ether, alkyl polyglucoside and sulfosuccinate, wherein the mass ratio of fatty alcohol polyoxyethylene ether, alkyl polyglucoside and sulfosuccinate is 5:3:2. The fatty alcohol polyoxyethylene ether, alkyl polyglucoside and sulfosuccinate are mixed according to the mass ratio and then added to the reaction system. The mixture is stirred at 55°C for 0.8 hours.

[0067] Shear emulsification: The obtained primary emulsion was slowly dripped into a 2% acrylate core-shell emulsion at a stirring rate of 800-1000 rpm, and the reaction was continued for 8 minutes. Then the stirring rate was increased to 2500-3200 rpm, the temperature was 50-55℃, and emulsification was carried out for 3.5 hours to obtain a composite emulsion.

[0068] Add a compound thickener to the obtained composite emulsion and stir for at least 20 minutes to obtain a water-soluble polyvinyl butyral emulsion with a network structure. The compound thickener includes a hydrophobically modified alkali-swellable thickener and a hydrophobically modified polyurethane thickener. The hydrophobic modified alkali-swelling thickener was diluted with 5-10 times its volume of deionized water to obtain an aqueous solution of the hydrophobic modified alkali-swelling thickener. A hydrophobic modified polyurethane thickener is dissolved in a mixed solvent to obtain an aqueous solution of the hydrophobic modified polyurethane thickener, wherein the mixed solvent is deionized water and ethylene glycol; At a temperature of 50-60°C and a rotation speed of 800-1000 rpm, slowly add an aqueous solution of hydrophobic modified alkali-swelling thickener and react for 18 minutes. Then lower the temperature of the reaction system to 30-35℃, rotate the speed to 400-500 rpm, slowly add the aqueous solution of hydrophobic modified polyurethane thickener, stir for 18 minutes, and let the reaction system stand for 12 hours after the reaction is completed.

[0069] Comparative Example 1 Water-soluble polyvinyl butyral emulsion, comprising the following components in parts by weight: 100 parts PVA; 200 parts ethanol; 20 parts composite emulsifier; 200 parts alkali solution; 5-15 parts acrylate core-shell emulsion; and 2-8 parts compound thickener. The preparation steps include the following: Dissolution: Dissolve PVB in ethanol at a temperature of 50-60℃ for 1-3 hours to obtain a solution; Alkali-catalyzed emulsification: The obtained solution is kept at 50-60℃, a composite emulsifier is added, and the mixture is stirred for 0.5-1 hour. During the reaction, a hot alkaline solution at 55℃ is slowly added dropwise to the reaction system, and the mixture is stirred for 0.5-1 hour to obtain the primary emulsion.

[0070] The composite emulsifier comprises fatty alcohol polyoxyethylene ether, alkyl polyglucoside and sulfosuccinate, wherein the mass ratio of fatty alcohol polyoxyethylene ether, alkyl polyglucoside and sulfosuccinate is 5:3:2. The fatty alcohol polyoxyethylene ether, alkyl polyglucoside and sulfosuccinate are mixed according to the mass ratio and then added to the reaction system. The mixture is stirred at 50°C for 0.5 hours.

[0071] Shear emulsification: The obtained primary emulsion is slowly dripped into an acrylate core-shell emulsion with a concentration of 1-3% at a stirring rate of 800-1000 rpm, and the reaction is continued for 5-10 minutes. Then the stirring rate is increased to 2500-3200 rpm, the temperature is 50-55℃, and emulsification is carried out for 3-4 hours to obtain a composite emulsion.

[0072] Add a compound thickener to the obtained composite emulsion and stir for at least 20 minutes to obtain a water-soluble polyvinyl butyral emulsion with a network structure. The compound thickener includes a hydrophobically modified alkali-swellable thickener and a hydrophobically modified polyurethane thickener. The hydrophobic modified alkali-swelling thickener was diluted with 5-10 times its volume of deionized water to obtain an aqueous solution of the hydrophobic modified alkali-swelling thickener. A hydrophobic modified polyurethane thickener is dissolved in a mixed solvent to obtain an aqueous solution of the hydrophobic modified polyurethane thickener, wherein the mixed solvent is deionized water and ethylene glycol; At a temperature of 50-60°C and a rotation speed of 800-1000 rpm, slowly add an aqueous solution of hydrophobic modified alkali-swelling thickener and react for 15-20 minutes. Then lower the temperature of the reaction system to 30-35℃, rotate the speed to 400-500 rpm, slowly add the aqueous solution of hydrophobic modified polyurethane thickener, stir for 15-20 minutes, and let the reaction system stand for 3-15 hours after the reaction is completed.

[0073] Comparative Example 2 Water-soluble polyvinyl butyral emulsion, comprising the following components in parts by weight: PVA 80-120 parts; ethanol 200-220 parts; composite plasticizer 15-25 parts; composite emulsifier 15-25 parts; alkali solution 180-220 parts; acrylate core-shell emulsion 5-15 parts; compound thickener 2-8 parts. The preparation steps include the following: Dissolution: Dissolve PVB in ethanol at a temperature of 50-60℃ for 1-3 hours to obtain a solution; Alkali-catalyzed emulsification: Add plasticizer to the obtained solution and stir evenly. While maintaining the temperature at 50-60℃, add composite emulsifier and stir for 0.5-1 hour. During the reaction, slowly add hot alkaline solution at 55℃ to the reaction system and stir the reaction for 0.5-1 hour to obtain primary emulsion.

[0074] The composite plasticizer comprises triethylene glycol diisooctanoate, acetylated tributyl citrate, and epoxy acetylated linoleate methyl ester, wherein the mass ratio of triethylene glycol diisooctanoate, acetylated tributyl citrate, and epoxy acetylated linoleate methyl ester is 8:1.5:0.5; The steps for adding the composite plasticizer are as follows: first, add triethylene glycol diisooctanoate to the reaction system and stir for 5-10 minutes; then add acetylacetic acid tributyl ester to the reaction system and stir for 5-10 minutes; finally, add epoxy acetylacetic acid methyl ester to the reaction system and stir for 15-20 minutes.

[0075] The composite emulsifier comprises fatty alcohol polyoxyethylene ether, alkyl polyglucoside and sulfosuccinate, wherein the mass ratio of fatty alcohol polyoxyethylene ether, alkyl polyglucoside and sulfosuccinate is 5:3:2. The fatty alcohol polyoxyethylene ether, alkyl polyglucoside and sulfosuccinate are mixed according to the mass ratio and added to the reaction system, and stirred at 50-60℃ for 0.5-1 hours.

[0076] Shear emulsification: The obtained primary emulsion is slowly dripped into an acrylate core-shell emulsion with a concentration of 1-3% at a stirring rate of 800-1000 rpm, and the reaction is continued for 5-10 minutes. Then the stirring rate is increased to 2500-3200 rpm, the temperature is 50-55℃, and emulsification is carried out for 3-4 hours to obtain a composite emulsion.

[0077] Add a compound thickener to the obtained composite emulsion and stir for at least 20 minutes to obtain a water-soluble polyvinyl butyral emulsion with a network structure. The compound thickener includes a hydrophobically modified alkali-swellable thickener and a hydrophobically modified polyurethane thickener. The hydrophobic modified alkali-swelling thickener was diluted with 5-10 times its volume of deionized water to obtain an aqueous solution of the hydrophobic modified alkali-swelling thickener. A hydrophobic modified polyurethane thickener is dissolved in a mixed solvent to obtain an aqueous solution of the hydrophobic modified polyurethane thickener, wherein the mixed solvent is deionized water and ethylene glycol; At a temperature of 50-60°C and a rotation speed of 800-1000 rpm, slowly add an aqueous solution of hydrophobic modified alkali-swelling thickener and react for 15-20 minutes. Then lower the temperature of the reaction system to 30-35℃, rotate the speed to 400-500 rpm, slowly add the aqueous solution of hydrophobic modified polyurethane thickener, stir for 15-20 minutes, and let the reaction system stand for 3-15 hours after the reaction is completed.

[0078] Comparative Example 3 Water-soluble polyvinyl butyral emulsion, comprising the following components in parts by weight: PVA 80-120 parts; ethanol 200-220 parts; composite plasticizer 15-25 parts; composite emulsifier 15-25 parts; alkali solution 180-220 parts; acrylate core-shell emulsion 5-15 parts; compound thickener 2-8 parts. The preparation steps include the following: Dissolution: Dissolve PVB in ethanol at a temperature of 50-60℃ for 1-3 hours to obtain a solution; Alkali-catalyzed emulsification: Add plasticizer to the obtained solution and stir evenly. While maintaining the temperature at 50-60℃, add composite emulsifier and stir for 0.5-1 hour. During the reaction, slowly add hot alkaline solution at 55℃ to the reaction system and stir the reaction for 0.5-1 hour to obtain primary emulsion.

[0079] The composite plasticizer comprises triethylene glycol diisooctanoate, acetylated tributyl citrate, and epoxy acetylated linoleate methyl ester, wherein the mass ratio of triethylene glycol diisooctanoate, acetylated tributyl citrate, and epoxy acetylated linoleate methyl ester is 8:1.5:0.5; The steps for adding the composite plasticizer are as follows: first, add triethylene glycol diisooctanoate to the reaction system and stir for 5-10 minutes; then add acetylacetic acid tributyl ester to the reaction system and stir for 5-10 minutes; finally, add epoxy acetylacetic acid methyl ester to the reaction system and stir for 15-20 minutes.

[0080] The composite emulsifier comprises fatty alcohol polyoxyethylene ether, alkyl polyglucoside and sulfosuccinate, wherein the mass ratio of fatty alcohol polyoxyethylene ether, alkyl polyglucoside and sulfosuccinate is 5:3:2. The fatty alcohol polyoxyethylene ether, alkyl polyglucoside and sulfosuccinate are mixed according to the mass ratio and added to the reaction system, and stirred at 50-60℃ for 0.5-1 hours.

[0081] Shear emulsification: The obtained primary emulsion is slowly dripped into an acrylate core-shell emulsion with a concentration of 1-3% at a stirring rate of 800-1000 rpm, and the reaction is continued for 5-10 minutes. Then the stirring rate is increased to 2500-3200 rpm, the temperature is 50-55℃, and emulsification is carried out for 3-4 hours to obtain a composite emulsion.

[0082] Add a compound thickener to the obtained composite emulsion and stir for at least 20 minutes to obtain a water-soluble polyvinyl butyral emulsion with a network structure. The compound thickener includes a hydrophobically modified alkali-swellable thickener and a hydrophobically modified polyurethane thickener. The hydrophobic modified alkali-swelling thickener was diluted with 5-10 times its volume of deionized water to obtain an aqueous solution of the hydrophobic modified alkali-swelling thickener. A hydrophobic modified polyurethane thickener is dissolved in a mixed solvent to obtain an aqueous solution of the hydrophobic modified polyurethane thickener, wherein the mixed solvent is deionized water and ethylene glycol; At a temperature of 50-60°C and a rotation speed of 800-1000 rpm, slowly add an aqueous solution of hydrophobic modified alkali-swelling thickener and react for 15-20 minutes. Then lower the temperature of the reaction system to 30-35℃, rotate the speed to 400-500 rpm, slowly add the aqueous solution of hydrophobic modified polyurethane thickener, stir for 15-20 minutes, and let the reaction system stand for 3-15 hours after the reaction is completed.

[0083] Experimental example: In the above experimental examples 1-3, the amount of ethanol added during the preparation process and the amount of ethanol recovered after condensation were almost the same, indicating that there was almost no ethanol residue and no VOCs in the emulsion.

[0084] The stability performance of the water-soluble polyvinyl butyral emulsion prepared using the formulation and preparation method of this embodiment was tested. The method was as follows: the obtained water-soluble polyvinyl butyral emulsions were left to stand for 0 days, 30 days, 90 days and 180 days, respectively, and the separation was observed. The storage stability test results of this invention are shown in Table 1 below: Table 1

[0085] As can be seen from the above, the water-soluble polyvinyl butyral emulsion prepared by the formula and preparation method provided by the present invention has good product stability.

[0086] In the field of coatings, the emulsion in this invention replaces solvent-based PVB, and its adhesion and weather resistance performance meet the requirements.

[0087] The optional implementation methods of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above implementation methods. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0088] It should also be noted that the various specific technical features described in the above embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the embodiments of the present invention will not describe the various possible combinations separately.

[0089] Furthermore, various different implementations of the present invention can be combined arbitrarily, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed in the present invention.

Claims

1. A method for preparing a water-soluble polyvinyl butyral emulsion, characterized in that, The preparation steps include the following: Dissolution: Dissolve PVB in ethanol at a temperature of 50-60℃ for 1-3 hours to obtain a solution; Alkali-catalyzed emulsification: Add composite plasticizer and composite emulsifier sequentially to the obtained solution, stir and mix, then slowly add alkali solution dropwise to the reaction system, and react for 0.2-0.8 hours to obtain the primary emulsion; Shear emulsification: Add acrylate core-shell emulsion to the obtained primary emulsion, and then perform high-speed shear emulsification to obtain a composite emulsion; Add a compound thickener to the obtained composite emulsion and stir for at least 20 minutes to obtain a water-soluble polyvinyl butyral emulsion with a network structure. The composite plasticizer includes triethylene glycol diisooctanoate, tributyl acetyl citrate, and methyl epoxyacetyl linoleate. The composite emulsifier includes fatty alcohol polyoxyethylene ether, alkyl polyglucoside and sulfosuccinate; The compound thickener includes a hydrophobically modified alkali-swellable thickener and a hydrophobically modified polyurethane thickener.

2. The preparation method according to claim 1, characterized in that, The mass ratio of triethylene glycol diisooctanoate, acetylated tributyl citrate, and epoxy acetylated linoleate methyl ester is 8:1.5:0.5; The steps for adding the composite plasticizer are as follows: first, add triethylene glycol diisooctanoate to the reaction system and stir for 5-10 minutes; then add acetylacetic acid tributyl ester to the reaction system and stir for 5-10 minutes; finally, add epoxy acetylacetic acid methyl ester to the reaction system and stir for 15-20 minutes.

3. The preparation method according to claim 2, characterized in that, The mass ratio of the fatty alcohol polyoxyethylene ether, alkyl polyglucoside and sulfosuccinate is 5:3:

2. The fatty alcohol polyoxyethylene ether, alkyl polyglucoside and sulfosuccinate are mixed according to the mass ratio and then added to the reaction system. The mixture is stirred at 50-60℃ for 0.5-1 hours.

4. The preparation method according to claim 3, characterized in that, The specific steps of the alkali-catalyzed emulsification are as follows: Add the composite plasticizer to the obtained solution and stir evenly. While maintaining the temperature at 50-60℃, add the composite emulsifier and stir for 0.5-1 hour. During the reaction, slowly add hot alkaline solution at 55℃ to the reaction system and stir the reaction for 0.5-1 hour to obtain the primary emulsion.

5. The preparation method according to claim 4, characterized in that, The shear emulsification process is as follows: The obtained primary emulsion was slowly added dropwise with an acrylate core-shell emulsion of 1-3% at a stirring speed of 800-1000 rpm, and the reaction was continued for 5-10 minutes. Then the stirring speed was increased to 2500-3200 rpm and the temperature was 50-55℃ for emulsification for 3-4 hours to obtain a composite emulsion.

6. The preparation method according to claim 5, characterized in that, The hydrophobic modified alkali-swelling thickener was diluted with 5-10 times its volume of deionized water to obtain an aqueous solution of the hydrophobic modified alkali-swelling thickener. A hydrophobic modified polyurethane thickener is dissolved in a mixed solvent to obtain an aqueous solution of the hydrophobic modified polyurethane thickener, wherein the mixed solvent is deionized water and ethylene glycol; At a temperature of 50-60°C and a rotation speed of 800-1000 rpm, slowly add an aqueous solution of hydrophobic modified alkali-swelling thickener and react for 15-20 minutes. Next, lower the temperature of the reaction system to 30-35℃, rotate the spindle at 400-500 rpm, slowly add the hydrophobic modified polyurethane thickener aqueous solution, and stir for 15-20 minutes. After the reaction is complete, let it stand for 3-15 hours.

7. A water-soluble polyvinyl butyral emulsion, characterized in that, It is prepared by the preparation method according to any one of claims 1-6.

8. The water-soluble polyvinyl butyral emulsion according to claim 7, characterized in that, Includes the following components, in parts by weight: 80-120 parts PVA; 200-220 parts ethanol; 15-25 parts compound plasticizer; 15-25 parts compound emulsifier; 180-220 parts alkali solution; 5-15 parts acrylate core-shell emulsion; 2-8 parts compound thickener; The composite plasticizer includes triethylene glycol diisooctanoate, tributyl acetyl citrate, and methyl epoxyacetyl linoleate. The composite emulsifier includes fatty alcohol polyoxyethylene ether, alkyl polyglucoside and sulfosuccinate; The compound thickener includes a hydrophobic modified alkali-swellable thickener and a hydrophobic modified polyurethane thickener; Ethanol is evaporated, condensed, and recovered.

9. The water-soluble polyvinyl butyral emulsion according to claim 7, characterized in that, Includes the following components, in parts by weight: 100 parts PVA; 220 parts ethanol; 20 parts compound plasticizer; 20 parts compound emulsifier; 200 parts alkali solution; 10 parts acrylate core-shell emulsion; 5 parts compound thickener; The composite plasticizer includes triethylene glycol diisooctanoate, tributyl acetyl citrate, and methyl epoxyacetyl linoleate. The composite emulsifier includes fatty alcohol polyoxyethylene ether, alkyl polyglucoside and sulfosuccinate; The compound thickener includes a hydrophobic modified alkali-swellable thickener and a hydrophobic modified polyurethane thickener; Ethanol is evaporated, condensed, and recovered.

10. The application of the water-soluble polyvinyl butyral emulsion according to claim 9 in the fields of metals, glass, wood, and plastics.

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