Full-water-based polyvinyl butyral solution as well as preparation method and application thereof

Abstract

The invention relates to the technical field of high polymer materials, and particularly discloses a full-water-based polyvinyl butyral solution and a preparation method and application thereof, and the preparation method comprises the following steps: stirring deionized water and PVA resin at the temperature of 90-98 DEG C until the PVA resin is completely dissolved to obtain a PVA aqueous solution; slowly dropwise adding a degradation agent into the aqueous solution to obtain a degraded PVA aqueous solution; cooling the obtained degraded PVA water solution to 2-7 DEG C, adding n-butyraldehyde, dropwise adding concentrated hydrochloric acid, heating to 2-15 DEG C, maintaining the reaction for 1.5-2.5 hours, heating to 10-25 DEG C, and maintaining the reaction for 2-4 hours; sampling in the reaction process to measure the light transmittance of the reaction liquid under the wavelength of 600nm, slowly dropwise adding the compounded composite polymerization inhibitor A into the reaction system when the light transmittance is reduced to 80-85%, and continuously stirring for 8-15 minutes so as to cut off the acetalation process in the reaction system; and slowly dropwise adding a composite polymerization inhibitor B into the reaction system, and carrying out a stirring reaction for 6-24 min to terminate acetalation in the reaction system so as to obtain the full-water-based polyvinyl butyral solution.

Description

Technical Field

[0001] This invention relates to the field of polymer materials, specifically to an all-aqueous polyvinyl butyral solution, its preparation method, and its application. Background Technology

[0002] Polyvinyl butyral (PVB) is an important polymer material with a wide range of applications. It has excellent optical properties, high adhesion to various substrates such as glass, ceramics, metals, and cellulose, and can be processed and applied through various convenient methods such as solution processing and melting.

[0003] Conventional PVB preparation involves reacting polyvinyl alcohol (PVB) in an aqueous solution with butyraldehyde in the presence of an acid catalyst and an emulsifier. The resulting PVB is typically in solid or powder form. The preparation process mainly includes acid-catalyzed condensation reaction, neutralization, filtration, washing, and drying. This process is complex and involves a significant amount of organic solvents during production and use. These solvents are volatile, polluting the environment, harming human health, and posing serious safety hazards. Furthermore, the organic solvents require disposal, which is costly, resulting in a high overall cost.

[0004] The existing patent CN108070042A provides a method for preparing all-aqueous polyvinyl butyral (PVB). This patent mentions a process involving adding polyvinyl alcohol, phthalic anhydride, and pure water to a container to obtain a polyvinyl alcohol solution, and then reacting the polyvinyl alcohol solution with n-butyraldehyde and concentrated hydrochloric acid to prepare all-aqueous polyvinyl butyral (PVB). However, this preparation method has several technical problems:

[0005] 1. The acetalization reaction is inefficient and takes a long time, leading to increased energy consumption;

[0006] 2. The endpoint of the acetalization reaction cannot be determined, and PVB particles may agglomerate, at which point the solid particles can no longer dissolve in water.

[0007] 3. The stability of the prepared all-aqueous polyvinyl butyral solution could not be verified. During storage, PVB may re-aggregate. Summary of the Invention

[0008] To overcome the aforementioned technical problems in the prior art, this invention provides an all-aqueous polyvinyl butyral solution, its preparation method, and its application. By optimizing the formulation and preparation method of the all-aqueous polyvinyl butyral solution, an all-aqueous polyvinyl butyral solution is prepared, improving reaction efficiency without prolonging the reaction time. Furthermore, the preparation process is more environmentally friendly as it eliminates organic solvent volatile pollution, and the resulting product is free of organic solvents, making it safer. Simultaneously, it yields an all-aqueous polyvinyl butyral solution with strong stability, meeting the diverse needs of the market.

[0009] To achieve the above-mentioned technical effects, embodiments of the present invention provide the following steps:

[0010] Deionized water and PVA resin are stirred at a temperature of 90-98℃ until the PVA resin is completely dissolved to obtain a PVA aqueous solution.

[0011] The degradation agent was slowly added dropwise to the obtained PVA aqueous solution, and the viscosity was measured during the reaction until the viscosity dropped to 750-850. A PVA-degraded aqueous solution was obtained;

[0012] Cool the obtained degraded PVA aqueous solution to 2-7℃, add n-butyraldehyde, and dropwise add concentrated hydrochloric acid. Stir evenly, raise the temperature to 2-15℃, maintain the reaction for 1.5-2.5 hours, then raise the temperature to 10-25℃ and maintain the reaction for 2-4 hours.

[0013] During the reaction, the transmittance of the reaction solution was measured at a wavelength of 600 nm. When the transmittance dropped to 80-85%, the compounded polymerization inhibitor A was slowly added dropwise to the reaction system, and the mixture was stirred continuously for 8-15 minutes to cut off the acetalization process in the reaction system. Then, the compound polymerization inhibitor B was slowly added dropwise to the reaction system, and the mixture was stirred for 6-24 minutes to terminate the acetalization process in the reaction system, resulting in an all-aqueous polyvinyl butyral solution.

[0014] The composite polymerization inhibitor A comprises triethylamine, triethanolamine, and a phosphate buffer pair;

[0015] The composite polymerization inhibitor B includes sodium bisulfite, polysorbate 80, and polyvinylpyrrolidone.

[0016] Preferably, the mass ratio of the triethylamine, triethanolamine, and phosphate buffer pair is 3:1:3;

[0017] Triethylamine, triethanolamine, and phosphate buffer were added to deionized water in a certain mass ratio and stirred until homogeneous to obtain composite polymerization inhibitor A.

[0018] Preferably, the step of adding composite polymerization inhibitor B is as follows: first, sodium bisulfite is added dropwise to the reaction system, stirred evenly, and the reaction continues for 2-8 minutes; then, polysorbate 80 is added dropwise to the reaction system, and the reaction continues for 2-8 minutes; finally, polyvinylpyrrolidone is added dropwise to the reaction system, stirred evenly, and the reaction continues for 2-8 minutes.

[0019] Preferably, the amount of composite polymerization inhibitor B added is 8%-15% of the mass of butyraldehyde.

[0020] Preferably, the reaction further includes adding a pH adjuster after adding the composite polymerization inhibitor B, wherein the pH adjuster is a 20% triethylamine aqueous solution. The addition is stopped when the pH value in the reaction system is maintained at 6.5-7.5, and the mixture is stirred continuously for 20-35 minutes to obtain an all-aqueous polyvinyl butyral solution.

[0021] Preferably, the method further includes adding a hydrophilic modifier to the obtained aqueous polyvinyl butyral solution, wherein the amount of hydrophilic modifier added is 0.5-2% of the mass of the aqueous polyvinyl butyral solution.

[0022] This invention also provides an all-aqueous polyvinyl butyral solution, prepared by the above method, wherein the degree of acetalization of the all-aqueous polyvinyl butyral solution is 30-50%, and the turbidity of the 10% solids content all-aqueous polyvinyl butyral solution at 25°C is ≤5 NTU.

[0023] Preferably, it comprises the following components, in parts by weight:

[0024] 350-450 parts PVA resin, 10-30 parts butyraldehyde, 1-10 parts hydrochloric acid, 50-150 parts deionized water, 1-10 parts degradation agent, 0.5-2.5 parts composite polymerization inhibitor A, and 0.5-2.5 parts composite polymerization inhibitor B;

[0025] The degradation agent is hydrogen peroxide;

[0026] The composite polymerization inhibitor A comprises triethylamine, triethanolamine, and a phosphate buffer pair;

[0027] The phosphate buffer pair includes dipotassium hydrogen phosphate and potassium dihydrogen phosphate;

[0028] The composite polymerization inhibitor B includes sodium bisulfite, polysorbate 80, and polyvinylpyrrolidone.

[0029] Preferably, it comprises the following components, in parts by weight:

[0030] 400 parts PVA resin, 20 parts butyraldehyde, 5 parts hydrochloric acid, 100 parts deionized water, 5 parts degradation agent, 2 parts composite polymerization inhibitor A, and 2 parts composite polymerization inhibitor B;

[0031] The degradation agent is hydrogen peroxide;

[0032] The composite polymerization inhibitor A comprises triethylamine, triethanolamine, and a phosphate buffer pair;

[0033] The phosphate buffer pair includes dipotassium hydrogen phosphate and potassium dihydrogen phosphate;

[0034] The composite polymerization inhibitor B includes sodium bisulfite, polysorbate 80, and polyvinylpyrrolidone.

[0035] Preferably, the hydrophilic modifier is one or more of glycerol, polyethylene glycol, or pentanediol.

[0036] This invention also provides an application of an all-aqueous polyvinyl butyral solution in the fields of inks and coatings.

[0037] The technical solution provided by this invention has at least the following technical effects: By improving the preparation method of all-water-based polyvinyl butyral solution, the use of organic solvents is reduced, thereby reducing environmental pollution and harm to the human body. During the preparation process, the transmittance at a wavelength of 600 nm is measured periodically. When the transmittance drops to 80-85%, composite polymerization inhibitor A and composite polymerization inhibitor B are added to the reaction system. Composite polymerization inhibitor A and composite polymerization inhibitor B play a key role in the preparation of all-water-based polyvinyl butyral solution. The main purpose of composite polymerization inhibitor A is to neutralize the hydrochloric acid in the reaction system, thereby cutting off the acetalization process. Composite polymerization inhibitor B further controls the degree of acetalization in the reaction without acetalization, avoiding particle agglomeration during the reaction process, thus maintaining the degree of acetalization at 30-50% to ensure water solubility and improve the stability of the prepared all-water-based polyvinyl butyral solution.

[0038] Other features and advantages of the embodiments of the present invention will be described in detail in the following detailed description section. Detailed Implementation

[0039] 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.

[0040] 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.

[0041] In existing technologies, the polyvinyl butyral products prepared are all in solid or powder form, and they need to be dissolved during use before being applied in various fields, such as inks, which makes the operation more complicated.

[0042] Existing solutions for all-aqueous polyvinyl butyral solutions are few and far between, and those that have been reported have many technical problems. For example, the method for preparing all-aqueous polyvinyl butyral provided in the background section involves adding phthalic anhydride as a modifier to the reaction system, but this prolongs the overall reaction time, increases raw material and energy costs, has low preparation efficiency, and makes it difficult to determine the acetalization endpoint. Furthermore, repeated washing is required to remove acidic residues and small molecule byproducts, significantly increasing wastewater treatment costs. In addition, the stability of the all-aqueous polyvinyl butyral solution prepared by the method in the background section is uncertain. The product prepared by the above method cannot be stored for a long time due to its poor stability, thus making it unusable.

[0043] Given the aforementioned prior art, it is necessary to provide a fully aqueous polyvinyl butyral solution product that does not use organic solvents in the preparation process, is environmentally friendly in the production process, and can produce good water solubility and strong long-term storage stability.

[0044] This invention provides a method for preparing an all-aqueous polyvinyl butyral solution, comprising the following steps:

[0045] Deionized water and PVA resin are stirred at a temperature of 90-95℃ until the PVA resin is completely dissolved to obtain a PVA aqueous solution.

[0046] The degradation agent was slowly added dropwise to the obtained PVA aqueous solution. During the reaction, the viscosity was measured periodically until the viscosity dropped to 750-850 g / L. A PVA-degraded aqueous solution was obtained;

[0047] Cool the obtained degraded PVA aqueous solution to 2-7℃, add n-butyraldehyde, and dropwise add concentrated hydrochloric acid. Stir evenly and raise the temperature to 5-10℃, maintain the reaction for 1.5-2 hours, and continue to raise the temperature to 15-20℃, maintain the reaction for 2-4 hours.

[0048] During the reaction, the transmittance of the reaction solution was measured at a wavelength of 600 nm at regular intervals. When the transmittance dropped to 80-85%, the compounded polymerization inhibitor A was slowly added dropwise to the reaction system, and the mixture was stirred continuously for 8-15 minutes to cut off the acetalization process in the reaction system. Then, the compound polymerization inhibitor B was slowly added dropwise to the reaction system, and the mixture was stirred for 6-24 minutes to terminate the acetalization process in the reaction system, resulting in an all-aqueous polyvinyl butyral solution.

[0049] The composite polymerization inhibitor A comprises triethylamine, triethanolamine, and a phosphate buffer pair;

[0050] The composite polymerization inhibitor B includes sodium bisulfite, polysorbate 80, and polyvinylpyrrolidone.

[0051] In one possible embodiment, the present invention provides a method for preparing an all-aqueous polyvinyl butyral solution. The present invention employs a method of first dissolving PVA resin with deionized water at a temperature of 90-98°C, preferably 92-95°C, for a preferred time of 1 hour. The mass ratio of PVA resin to deionized water is preferably 4:1. Under these conditions, PVA can be quickly dissolved to obtain a PVA aqueous solution.

[0052] Next, a degradation agent, preferably hydrogen peroxide, is added to the obtained PVA aqueous solution. After addition, the viscosity value is measured periodically, which can be set to measure the viscosity value every 5 minutes. The specific time interval can also be set on-site. The specific measurement method is conventional and will not be elaborated in detail here. When the PVA aqueous solution degrades to a viscosity value of 750-850... 800 is preferred This viscosity value has high uniformity, and the molecular weight is relatively small with a short molecular chain, which is beneficial to improving the efficiency of PVB preparation. At the same time, it provides favorable prerequisites for preparing an all-aqueous PVB aqueous solution. The PVA solution with a certain viscosity value is cooled to room temperature to prepare for subsequent PVB preparation.

[0053] Using hydrogen peroxide as a PVA degrading agent can efficiently reduce the viscosity of PVA resin to 750-800. 800 is preferred The PVA solution with this viscosity value has a more uniform molecular weight, and the hydrogen peroxide component is non-toxic. After participating in the reaction, it will exist in the solution in the form of water, requiring no additional treatment. The operation is simple and the economic cost is low.

[0054] To ensure the smooth progress of the reaction, the obtained room-temperature PVB aqueous solution needs to be rapidly cooled to 2-7°C, preferably 5°C. This rapid cooling can be achieved by using a chilled brine heat exchanger. After the temperature stabilizes at the set value, a certain amount of n-butyraldehyde is added, and concentrated hydrochloric acid (35%) is slowly added dropwise at a rate of 2-8 mL / min (based on a 500L reactor). The reaction is carried out for 1.5-2.5 hours at a temperature between 2-15°C, preferably 2 hours at 5-10°C. Then, the temperature is raised to 10-25°C and the reaction is carried out for 2-4 hours, preferably 3 hours at 15-20°C, to obtain a pre-reaction solution. PVB generation is achieved through a staged heating method. This method ensures the stability and completeness of the reaction. Specifically, the high-concentration reaction solution is reacted at a lower temperature. As the reaction proceeds, PVA and butyraldehyde raw materials begin to generate PVB. At this point, the reaction temperature needs to be increased to promote a more complete reaction.

[0055] In the above preparation process, the timing of adding composite polymerization inhibitor A and composite polymerization inhibitor B plays a crucial role in the final product. If they are added too early, the polyvinyl alcohol and n-butyraldehyde will not have fully reacted to form polyvinyl butyral, resulting in insufficient reaction and waste of raw materials. If they are added too late, the degree of acetalization will be high, which will lead to the failure of preparing an all-aqueous polyvinyl butyral solution.

[0056] During the reaction process, to enable more concrete control over acetalization and facilitate standardized operation, the transmittance of the reaction solution is measured periodically (e.g., every 2 minutes, or every 3 minutes, depending on the production status) at a wavelength of 600 nm. The 600 nm wavelength was chosen because it effectively avoids the light absorption of the reactant and product molecules themselves, ensuring the measurement results only reflect turbidity changes caused by particulate matter. Furthermore, the significant particle scattering effect at this wavelength allows for sensitive detection of the initial formation of nanoscale PVB particles in the reaction system. If a 400 nm wavelength were chosen, the PVA molecules themselves might absorb light, resulting in very low background transmittance, masking transmittance changes caused by particulate matter and leading to inaccurate measurements. While a 800 nm wavelength would have weaker molecular absorption, the detector sensitivity would decrease, and the scattering efficiency of particles for infrared light would be lower than for visible light, resulting in a weaker signal and less sensitive changes.

[0057] When the transmittance drops to 80-85% during the reaction process, composite polymerization inhibitor A needs to be added. This is because when the transmittance drops to 80-85%, the reaction system appears slightly milky white to the naked eye, with no obvious particles, indicating that the reaction is basically complete and progressing towards a higher degree of acetalization. Testing at this point shows an acetalization degree of 30-40%, and no phase transition has occurred. Adding composite polymerization inhibitor A at this stage effectively controls acetalization and is a key step in preparing an all-aqueous polyvinyl butyral solution. Add composite polymerization inhibitor A and maintain the reaction for 8-15 minutes. The inhibitor should be added dropwise uniformly within this time range, with the frequency determined by the time. Stirring should primarily employ high-shear dispersion, with the stirring rate determined based on actual operation. This allows the composite polymerization inhibitor A to interrupt acetalization in the reaction system. In addition to the above process conditions, composite polymerization inhibitor B needs to be added dropwise to the reaction system. Composite polymerization inhibitor B further terminates the acetalization degree in the reaction system and maintains the reaction for 6-24 minutes. Adding composite polymerization inhibitors A and B ensures that PVB is generated while more precisely terminating the acetalization degree before further reaction. The addition of both composite polymerization inhibitors A and B is indispensable. During the addition process, the temperature of the reaction system must be maintained between 45-50℃, and the pH value between 6.5-7.5. Only under these conditions can the polymerization inhibition reaction be effectively controlled. After polymerization inhibition is completed, the transmittance is measured. If the transmittance recovers to above 90%, the acetalization degree is controlled within 30-50%, and no particles are formed, then the preparation of the water-soluble polyvinyl butyral solution is successful. Composite polymerization inhibitor A includes triethylamine, triethanolamine, and a phosphate buffer pair; composite polymerization inhibitor B includes sodium bisulfite, polysorbate 80, and polyvinylpyrrolidone.

[0058] By periodically measuring the transmittance during the preparation of polyvinyl butyral solution, the timing of adding composite polymerization inhibitor A is determined based on the transmittance measurement. This process is quantifiable, operable, and easy to control. Composite polymerization inhibitor A is used to cut off the conditions for acetalization, and then composite polymerization inhibitor B is used to react with the residual raw materials to further terminate the degree of acetalization, thereby achieving the goal of controlling acetalization and preparing an all-aqueous polyvinyl butyral solution.

[0059] In the preparation of an all-aqueous polyvinyl butyral solution, if acetalization is not controlled in time, the resulting product will be solid, thus yielding polyvinyl butyral in its conventional state. Therefore, the composite polymerization inhibitor A plays a crucial role in controlling the acetalization process, and the selection of this component is particularly important. If the selection is inappropriate, the acetalization process cannot be effectively controlled, and an all-aqueous polyvinyl butyral solution cannot be prepared.

[0060] In this embodiment of the invention, the composite polymerization inhibitor A comprises triethylamine, triethanolamine, and a phosphate buffer pair, wherein the mass ratio of the triethylamine, triethanolamine, and the phosphate buffer pair is 3:1:3.

[0061] Triethylamine, triethanolamine, and phosphate buffer were added to deionized water in a certain mass ratio and stirred until homogeneous to obtain composite polymerization inhibitor A.

[0062] In one possible embodiment, the composite polymerization inhibitor A includes triethylamine, triethanolamine, and a phosphate buffer pair. Triethylamine can rapidly neutralize hydrochloric acid, thereby disrupting the catalytic conditions and providing the necessary conditions for terminating the reaction. It is the main force in terminating the catalytic conditions. However, using only triethylamine to disrupt the catalytic conditions has several drawbacks. Specifically, if only triethylamine is used to neutralize the reaction, the reaction process is rapid and exothermic. If triethylamine is added too quickly or is not dispersed evenly, the local pH value at the addition point in the system will rise sharply, which may lead to local over-alkalinity. This may cause the polyvinyl butyral molecular chains to aggregate and gel instantaneously, forming visible microgel particles, which in turn leads to the failure of the formation of the all-aqueous polyvinyl butyral solution.

[0063] To ensure a more stable reaction process, the pH of the reaction system is kept within the target range (6.5-7.5) to avoid drastic fluctuations. This allows for more precise control of the termination conditions for acetalization and prevents particle agglomeration due to excessively high local pH.

[0064] To address this, a triethanolamine and phosphate buffer pair were added. Triethanolamine, a weak organic base, was used to replace a portion of the triethylamine. Weak bases have a low degree of ionization and will not release large amounts of OH- ions instantaneously in aqueous solution. - The ions in the weak base will gradually ionize, slowly replenishing OH⁻, thus automatically buffering the rate of pH increase.

[0065] The phosphate buffer first creates a mild pH rise environment, followed by the smooth neutralization of hydrochloric acid by triethylamine in the buffer system. The phosphate buffer employs... This type of buffer produces no gas, is safe and controllable, and effectively resists sudden pH changes. When large quantities... During influx, conjugate base It will combine with it; when During the influx, conjugate acids It will neutralize. This is like a "chemical sponge," absorbing the "shock" released by the neutralization reaction, thereby effectively avoiding the possibility of sudden pH changes and reducing the probability of polyvinyl butyral aggregation.

[0066] By employing a mixture of composite polymerization inhibitors A, triethylamine can quickly neutralize the main hydrochloric acid, cutting off the prerequisite for the acetalization process. Triethanolamine can assist triethylamine and provide a stable subsequent buffer. The phosphate buffer can work synergistically to better control the environment, thereby avoiding the possibility of polyvinyl butyral solution particle agglomeration during the neutralization process.

[0067] If the amount of triethylamine is too low, the hydrochloric acid neutralization reaction will be insufficient, leaving some residual hydrochloric acid, which will cause the acetal reaction to continue, resulting in insufficient polymerization inhibition and failure to achieve the desired polymerization inhibition effect. If the amount of triethylamine is too high, the prepared all-aqueous polyvinyl butyral solution will contain excessive triethylamine, resulting in low product purity and affecting product performance. Therefore, the amount of components added in composite polymerization inhibitor A is also an important step.

[0068] The mass ratio of triethylamine, triethanolamine, and phosphate buffer was set at 3:1:3. This is because triethylamine is the primary neutralizer of hydrochloric acid, and its dosage is optimized based on the amount of hydrochloric acid added. The purpose is to rapidly consume most of the hydrochloric acid in the reaction system, ensuring reaction efficiency. Triethanolamine, being a weak base, acts as an auxiliary synergist. Its role is not to initiate a rapid initial reaction, but rather to provide a stable buffering capacity after rapid neutralization by triethylamine, preventing pH rebound or localized over-alkalinity. Therefore, its amount should not be too high, as excessive amounts can easily disrupt the equilibrium of the reaction system. The amount of phosphate buffer added is the same as that of triethylamine, aiming to enhance the buffering capacity. If the amount used is too low, it will not provide a sufficiently strong buffering capacity to effectively resist drastic pH fluctuations. The specific amount added is determined quantitatively based on the actual application; this quantitative process will not be elaborated upon here.

[0069] This invention removes hydrochloric acid from an all-aqueous polyvinyl butyral solution using triethylamine, avoiding the need for multiple washing methods as described in the prior art. This method not only synergistically inhibits polymerization but also reduces preparation steps and saves manufacturing costs.

[0070] Hydrochloric acid was used to neutralize the polyvinyl butyral by using a composite polymerization inhibitor A to cut off the conditions for acetalization. However, there was still residual butyraldehyde in the reaction system, which affected the quality of the all-aqueous polyvinyl butyral solution. In addition, the water-soluble polyvinyl butyral solution in the above system was not stable enough and would self-polymerize over a long period of time, making it unsuitable for market use.

[0071] In this embodiment of the invention, the composite polymerization inhibitor B includes sodium bisulfite, polysorbate 80, and polyvinylpyrrolidone;

[0072] The steps for adding composite polymerization inhibitor B are as follows: first, add sodium bisulfite dropwise into the reaction system, stir evenly and continue the reaction for 2-8 minutes; then add polysorbate 80 dropwise into the reaction system, continue the reaction for 2-8 minutes, and finally add polyvinylpyrrolidone dropwise into the reaction system, stir evenly and continue the reaction for 2-8 minutes.

[0073] In one possible embodiment, sodium bisulfite is added dropwise to the reaction system. Sodium bisulfite reacts with unreacted butyraldehyde to form a stable adduct, further and completely terminating acetalization, thus inhibiting polymerization and ultimately stopping the reaction. After terminating the chemical reaction, polysorbate 80, a small-molecule surfactant, is added. This surfactant quickly adsorbs onto the surface of polyvinyl butyral particles, reducing their interfacial energy and preventing immediate aggregation. Finally, polyvinylpyrrolidone is added. Given that polysorbate 80 has already initially stabilized the particles and altered the interfacial properties, the long molecular chains of polyvinylpyrrolidone can more readily and firmly adsorb onto the pretreated particle surface, synergistically forming a denser and thicker composite protective layer with polysorbate 80. This provides strong steric hindrance, preventing self-polymerization and ensuring long-term product storage stability.

[0074] This invention employs a segmented addition of the composite polymerization inhibitor B. The advantage of this approach is that it allows for a clearer understanding of the reaction process and facilitates reaction control. Besides this segmented addition method, sodium bisulfite, polysorbate 80, and polyvinylpyrrolidone can be pre-mixed to form an aqueous solution and added to the reaction system. However, this approach may result in an overly chaotic reaction. For example, residual n-butyraldehyde in the reaction system may react with sodium bisulfite and be adsorbed onto polysorbate 80 and polyvinylpyrrolidone, causing some interference in the preparation of the all-aqueous polyvinyl butyral solution.

[0075] The amounts of sodium bisulfite, polysorbate 80, and polyvinylpyrrolidone added vary. Sodium bisulfite is set based on the estimated residual n-butyraldehyde, while the amounts of polysorbate 80 and polyvinylpyrrolidone are measured based on the estimated amount of polyvinyl butyral. The specific amounts are determined by the actual production process and will not be elaborated further here.

[0076] The amount of composite polymerization inhibitor A and composite polymerization inhibitor B added is particularly important. If the amount added is insufficient, the acetalization process cannot be effectively controlled. If the amount added is too high, the acetalization process will also fail to be controlled, which will lead to the failure to generate an all-aqueous polyvinyl butyral solution.

[0077] In this embodiment of the invention, the mass ratio of the composite polymerization inhibitor A to the composite polymerization inhibitor B is 1:1, the amount of composite polymerization inhibitor A added is 1-1.2 times the molar amount of hydrochloric acid, and the amount of composite polymerization inhibitor B added is 8%-15% of the mass of n-butyraldehyde.

[0078] In one possible embodiment, the mass ratio of composite polymerization inhibitor A to composite polymerization inhibitor B is 1:1. Both composite polymerization inhibitor A and composite polymerization inhibitor B play equally important roles in the reaction system and are indispensable. The specific amounts of composite polymerization inhibitor A and composite polymerization inhibitor B added are determined based on the reaction raw materials. Specifically, the amount of composite polymerization inhibitor A added is calculated based on the amount of hydrochloric acid in the reaction system, and is 1-1.2 times the molar amount of hydrochloric acid. If the amount of composite polymerization inhibitor A added is less than 1-1.2 times the molar amount of hydrochloric acid, it cannot quickly and efficiently neutralize the hydrochloric acid, thus failing to quickly terminate the acetalization process and affecting the formation of the all-aqueous polyvinyl butyral solution. Excessive amounts will result in wasted raw materials.

[0079] The amount of composite polymerization inhibitor B added is predicted and set based on the amount of residual n-butyraldehyde in the reaction system. Therefore, the amount of sodium bisulfite added in composite polymerization inhibitor B is set to 8%-15% of the mass of butyraldehyde. If the amount of composite polymerization inhibitor B added is less than 8%-15%, n-butyraldehyde cannot be effectively removed. If it is more than 8%-15%, the amount added will be too large, wasting raw materials and introducing excess impurities into the reaction system.

[0080] The acetalization reaction was terminated by adding composite inhibitor A and composite inhibitor B as described above. However, the pH of the environment during the reaction process is particularly important. In the early stage, composite inhibitor A was controlled by triethanolamine and phosphate buffer, but after the addition of composite inhibitor B, the pH control was weaker. Especially after the addition of composite inhibitor B, the change in pH will also affect the formation of the final all-aqueous polyvinyl butyral solution.

[0081] In this embodiment of the invention, after slowly and uniformly adding composite polymerization inhibitor B to the reaction system, a pH adjusting agent is added dropwise to the reaction system. The pH adjusting agent is a 20% triethylamine aqueous solution. The addition is stopped when the pH value in the reaction system is maintained at 6.5-7.5, and the mixture is stirred continuously for 20-35 minutes to obtain an all-aqueous polyvinyl butyral solution.

[0082] In one possible embodiment, the pH of the system is precisely and slowly adjusted from weakly acidic (6-6.5) to the final target (neutral, 6.5-7.5) using this last dilute and mild alkaline solution. This avoids any drastic pH changes and allows for more precise control of the reaction. Antioxidants such as sodium vitamin C can also be added during this process to provide long-term antioxidant protection for the product. The solution is a 20% triethylamine aqueous solution, which is also added slowly.

[0083] By controlling the degree of acetalization during the reaction process, an all-aqueous polyvinyl butyral solution is obtained. During long-term storage, it may undergo self-polymerization. This is because the molecular weight of all-aqueous polyvinyl butyral is small and unstable under aqueous conditions, which is also the difficulty in maintaining an all-aqueous polyvinyl butyral solution.

[0084] In this embodiment of the invention, a hydrophilic modifier is added to the obtained aqueous polyvinyl butyral solution, wherein the amount of hydrophilic modifier added is 0.5 to 2% of the mass of the aqueous polyvinyl butyral solution.

[0085] In one possible embodiment, the hydrophilic modifier is preferably one or more of glycerol, polyethylene glycol, and / or pentanediol. The amount of hydrophilic modifier added is 0.5-2% of the all-aqueous polyvinyl butyral solution. When the hydrophilic modifier is composed of glycerol, polyethylene glycol, and pentanediol, it is added in a 1:1:1 ratio. When two hydrophilic modifiers are selected, they are also added in a 1:1 ratio. Although the polyvinyl butyral molecule contains hydrophilic groups such as hydroxyl groups, self-polymerization may still occur at high concentrations or under specific conditions. The addition of the hydrophilic modifier can compensate for this deficiency. Adding a hydrophilic modifier to a water-soluble polyvinyl butyral solution can effectively further prevent polyvinyl butyral self-polymerization and improve the stability of the solution. Especially when the hydrophilic modifier is a compound of glycerol, polyethylene glycol, and pentanediol in a 1:1:1 ratio, it can work synergistically to enhance the hydrophilicity of the system, optimize the interaction between polyvinyl butyral molecules, reduce the aggregation tendency caused by hydrophobic regions, thereby improving the homogeneity and storage performance of the solution. The addition of the hydrophilic modifier can significantly optimize the microstructure of the solution, improve water flux, flux recovery rate, and antifouling ability, and ensure the long-term stability of the polyvinyl butyral solution in application.

[0086] The determination standard for the aqueous polyvinyl butyral solution prepared above needs to be standardized for ease of management.

[0087] In this embodiment of the invention, the degree of acetalization of the all-aqueous polyvinyl butyral solution is 30-50%, and the turbidity of the 10% solids content all-aqueous polyvinyl butyral solution at 25°C is ≤5 NTU.

[0088] In one possible embodiment, the acetalization of the all-aqueous PVB solution prepared by the above reaction can be effectively controlled between 30-50%, making it significantly different from the conventional solid PVB form. The turbidity of the 10% solid content all-aqueous polyvinyl butyral solution at 25°C is ≤5 NTU, which further proves that the product does not exhibit self-polymerization during long-term storage, thus demonstrating its stability.

[0089] Currently, all PVB preparations are in powder or solid form, and the raw materials used contain a large amount of organic components. The components in the organic solvent are easily volatilized during the preparation process, making them environmentally unfriendly.

[0090] In this embodiment of the invention, the following components are included, in parts by weight:

[0091] 350-450 parts PVA resin, 10-30 parts butyraldehyde, 1-10 parts hydrochloric acid, 50-150 parts deionized water, 1-10 parts degradation agent, 0.5-2.5 parts composite polymerization inhibitor A, 0.5-2.5 parts composite polymerization inhibitor B, and 0.5-1 part pH fine-tuning agent;

[0092] The degradation agent is hydrogen peroxide;

[0093] The composite polymerization inhibitor A comprises triethylamine, triethanolamine, and a phosphate buffer pair;

[0094] The phosphate buffer pair includes dipotassium hydrogen phosphate and potassium dihydrogen phosphate;

[0095] The composite polymerization inhibitor B includes sodium bisulfite, polysorbate 80, and polyvinylpyrrolidone.

[0096] In one possible embodiment, in the above raw materials, triethylamine is used to neutralize hydrochloric acid, and the product is a water-soluble ionic compound. This compound is a small molecule impurity in the system, non-toxic, odorless, and highly water-soluble. It will not precipitate from the solution and has no negative impact on the appearance and stability of the product. During the subsequent film preparation and drying process, a small amount may precipitate out, but it usually does not affect the film performance. Additionally, sodium bisulfite reacts with residual n-butyraldehyde to generate a butyraldehyde sodium bisulfite adduct. This product is also water-soluble and chemically inert ionic compound. Due to its low residual amount and inertness, it is also... The process will not affect the transparency, stability, or subsequent application performance of the all-aqueous PVB solution. Hydrogen peroxide, as a degradation agent, will volatilize as a byproduct during the reaction, thus having no impact on product performance. The added polysorbate 80 and polyvinylpyrrolidone act as stabilizers and remain in the final product, forming part of the product's composition. Their function is to prevent PVB particle aggregation, which is crucial for the product's long-term stability. Apart from this, they will not affect the product's performance. While the phosphate buffer pair, as a buffer, will remain in the product, its water solubility does not affect the product's transparency or moldability. Using the raw materials provided by this invention, toxic and volatile organic solvent residues can be disinfected, and a superior all-aqueous polyvinyl butyral solution can be prepared.

[0097] In the technical solution provided by this invention, the amount of n-butyraldehyde is lower than that used conventionally. After precise proportioning in the early stage, the amount of residual butyraldehyde after the reaction generates PVB solution is small. Therefore, the use of sodium bisulfite can effectively remove excess n-butyraldehyde to terminate the reaction. At the same time, after the hydrochloric acid is neutralized by triethylamine, there is no need for multiple washing steps of hydrochloric acid in the reaction system. If triethylamine or sodium bisulfite is used alone for polymerization inhibition, in the experiment, for example, using only triethylamine can easily lead to local over-alkaliness, causing PVB particles to agglomerate and thus lose the water solubility property. Or, if only sodium bisulfite is used, since the hydrochloric acid is not neutralized, part of the reaction will still be carried out, resulting in incomplete termination of the reaction, causing the degree of acetalization to be greater than 50%, which also leads to a decrease in water solubility.

[0098] If composite polymerization inhibitor A and composite polymerization inhibitor B are directly mixed and added dropwise, the progress of acetalization can be controlled under certain controlled conditions. However, different degrees of reaction will occur, and the control of acetalization degree cannot reach the most ideal state.

[0099] The raw materials given above represent a range. In order to prepare better products, it is necessary to provide more specific formulas and dosages.

[0100] In this embodiment of the invention, the following components are included, in parts by weight:

[0101] 400 parts PVA resin, 20 parts butyraldehyde, 5 parts hydrochloric acid, 100 parts deionized water, 5 parts degradation agent, 2 parts composite polymerization inhibitor A, 2 parts composite polymerization inhibitor B, and 0.7 parts pH fine-tuning agent;

[0102] The degradation agent is hydrogen peroxide;

[0103] The composite polymerization inhibitor A comprises triethylamine, triethanolamine, and a phosphate buffer pair;

[0104] The phosphate buffer pair includes dipotassium hydrogen phosphate and potassium dihydrogen phosphate;

[0105] The composite polymerization inhibitor B includes sodium bisulfite, polysorbate 80, and polyvinylpyrrolidone.

[0106] In one possible embodiment, using the above-mentioned formulation of components and dosages, a fully aqueous PVB solution with superior performance and better stability can be prepared.

[0107] Experimental Example 1

[0108] An all-aqueous polyvinyl butyral solution comprises the following components, in parts by weight:

[0109] 350 parts PVA resin, 10 parts butyraldehyde, 1 part hydrochloric acid, 50 parts deionized water, 1 part degradation agent, 0.5 parts composite polymerization inhibitor A, 0.5 parts composite polymerization inhibitor B, and 0.5 parts pH fine-tuning agent;

[0110] The degradation agent is hydrogen peroxide; the composite polymerization inhibitor A includes triethylamine, triethanolamine and a phosphate buffer pair; the phosphate buffer pair includes dipotassium hydrogen phosphate and potassium dihydrogen phosphate; the composite polymerization inhibitor B includes sodium bisulfite, polysorbate 80 and polyvinylpyrrolidone.

[0111] Includes the following steps:

[0112] Deionized water and PVA resin were stirred at 90°C until the PVA resin was completely dissolved to obtain a PVA aqueous solution.

[0113] The degradation agent was slowly added dropwise to the obtained PVA aqueous solution, and the viscosity was measured during the reaction until the viscosity dropped to 750. A PVA-degraded aqueous solution was obtained;

[0114] Cool the obtained degraded PVA aqueous solution to 2-7℃, add n-butyraldehyde, and add concentrated hydrochloric acid dropwise. Stir well, raise the temperature to 2-15℃, maintain the reaction for 1.5 hours, and then raise the temperature to 10-25℃ and maintain the reaction for 2 hours.

[0115] During the reaction, the transmittance of the reaction solution was measured at a wavelength of 600 nm. When the transmittance dropped to 80-85%, a compounded polymerization inhibitor A (triethylamine, triethanolamine, and phosphate buffer were added to deionized water in a mass ratio of 3:1:3 and stirred until homogeneous) was added dropwise to the reaction system. The mixture was stirred continuously for 8 minutes to cut off the acetalization process in the reaction system. Then, a compound polymerization inhibitor B was added dropwise to the reaction system and the mixture was stirred for 6 minutes to terminate the acetalization process in the reaction system, resulting in an all-aqueous polyvinyl butyral solution.

[0116] The steps for adding composite polymerization inhibitor B are as follows: first, add sodium bisulfite dropwise into the reaction system, stir evenly and continue the reaction for 2 minutes; then add polysorbate 80 dropwise into the reaction system, continue the reaction for 2 minutes, and finally add polyvinylpyrrolidone dropwise into the reaction system, stir evenly and continue the reaction for 2 minutes.

[0117] Experiment Example 2

[0118] An all-aqueous polyvinyl butyral solution comprises the following components, in parts by weight:

[0119] 370 parts PVA resin, 15 parts butyraldehyde, 5 parts hydrochloric acid, 80 parts deionized water, 3 parts degradation agent, 1.5 parts composite polymerization inhibitor A, 1.5 parts composite polymerization inhibitor B, and 0.6 parts pH fine-tuning agent;

[0120] The degradation agent is hydrogen peroxide; the composite polymerization inhibitor A includes triethylamine, triethanolamine and a phosphate buffer pair; the phosphate buffer pair includes dipotassium hydrogen phosphate and potassium dihydrogen phosphate; the composite polymerization inhibitor B includes sodium bisulfite, polysorbate 80 and polyvinylpyrrolidone.

[0121] Includes the following steps:

[0122] Deionized water and PVA resin were stirred at 92°C until the PVA resin was completely dissolved to obtain a PVA aqueous solution.

[0123] The degradation agent was slowly added dropwise to the obtained PVA aqueous solution, and the viscosity was measured during the reaction until the viscosity dropped to 790. A PVA-degraded aqueous solution was obtained;

[0124] The obtained PVA degraded aqueous solution was cooled to 2-7℃, n-butyraldehyde was added, and concentrated hydrochloric acid was added dropwise. The mixture was stirred evenly, heated to 2-15℃, and the reaction was maintained for 1.8 hours. Then the temperature was raised to 10-25℃ and the reaction was maintained for 2.5 hours.

[0125] During the reaction, the transmittance of the reaction solution was measured at a wavelength of 600 nm. When the transmittance dropped to 80-85%, a compounded polymerization inhibitor A (triethylamine, triethanolamine, and phosphate buffer were added to deionized water in a mass ratio of 3:1:3 and stirred until homogeneous) was prepared by slowly adding the compounded polymerization inhibitor A to the reaction system. The mixture was stirred for 10 minutes to cut off the acetalization process in the reaction system. Then, a compound polymerization inhibitor B was slowly added to the reaction system and the mixture was stirred for 9 minutes to terminate the acetalization process in the reaction system, resulting in an all-aqueous polyvinyl butyral solution.

[0126] The steps for adding composite polymerization inhibitor B are as follows: first, add sodium bisulfite dropwise into the reaction system, stir evenly and continue the reaction for 3 minutes; then add polysorbate 80 dropwise into the reaction system, continue the reaction for 3 minutes, and finally add polyvinylpyrrolidone dropwise into the reaction system, stir evenly and continue the reaction for 3 minutes.

[0127] Experimental Example 3

[0128] An all-aqueous polyvinyl butyral solution comprises the following components, in parts by weight:

[0129] 400 parts PVA resin, 20 parts butyraldehyde, 5 parts hydrochloric acid, 100 parts deionized water, 5 parts degradation agent, 2 parts composite polymerization inhibitor A, 2 parts composite polymerization inhibitor B, and 0.7 parts pH fine-tuning agent;

[0130] The degradation agent is hydrogen peroxide; the composite polymerization inhibitor A includes triethylamine, triethanolamine and a phosphate buffer pair; the phosphate buffer pair includes dipotassium hydrogen phosphate and potassium dihydrogen phosphate; the composite polymerization inhibitor B includes sodium bisulfite, polysorbate 80 and polyvinylpyrrolidone.

[0131] Includes the following steps:

[0132] Deionized water and PVA resin were stirred at 95°C until the PVA resin was completely dissolved to obtain a PVA aqueous solution.

[0133] The degradation agent was slowly added dropwise to the obtained PVA aqueous solution, and the viscosity was measured during the reaction until the viscosity dropped to 800. A PVA-degraded aqueous solution was obtained;

[0134] Cool the obtained degraded PVA aqueous solution to 2-7℃, add n-butyraldehyde, and add concentrated hydrochloric acid dropwise. Stir well, raise the temperature to 2-15℃, maintain the reaction for 2 hours, and then raise the temperature to 10-25℃ and maintain the reaction for 3 hours.

[0135] During the reaction, the transmittance of the reaction solution was measured at a wavelength of 600 nm. When the transmittance dropped to 80-85%, a compounded polymerization inhibitor A (triethylamine, triethanolamine, and phosphate buffer were added to deionized water in a mass ratio of 3:1:3 and stirred until homogeneous) was added dropwise to the reaction system. The mixture was stirred continuously for 10 minutes to cut off the acetalization process in the reaction system. Then, a compound polymerization inhibitor B was added dropwise to the reaction system and the mixture was stirred for 15 minutes to terminate the acetalization process in the reaction system, resulting in an all-aqueous polyvinyl butyral solution.

[0136] The steps for adding composite polymerization inhibitor B are as follows: First, add sodium bisulfite to the reaction system, stir evenly and continue the reaction for 5 minutes; then add polysorbate 80 to the reaction system, continue the reaction for 5 minutes, and finally add polyvinylpyrrolidone to the reaction system, stir evenly and continue the reaction for 5 minutes.

[0137] Experiment Example 4

[0138] An all-aqueous polyvinyl butyral solution comprises the following components, in parts by weight:

[0139] 420 parts PVA resin, 25 parts butyraldehyde, 8 parts hydrochloric acid, 120 parts deionized water, 8 parts degradation agent, 2.0 parts composite polymerization inhibitor A, 2.0 parts composite polymerization inhibitor B, and 0.8 parts pH adjuster;

[0140] The degradation agent is hydrogen peroxide; the composite polymerization inhibitor A includes triethylamine, triethanolamine and a phosphate buffer pair; the phosphate buffer pair includes dipotassium hydrogen phosphate and potassium dihydrogen phosphate; the composite polymerization inhibitor B includes sodium bisulfite, polysorbate 80 and polyvinylpyrrolidone.

[0141] Includes the following steps:

[0142] Deionized water and PVA resin were stirred at 95°C until the PVA resin was completely dissolved to obtain a PVA aqueous solution.

[0143] The degradation agent was slowly added dropwise to the obtained PVA aqueous solution, and the viscosity was measured during the reaction until the viscosity dropped to 830. A PVA-degraded aqueous solution was obtained;

[0144] The obtained PVA degradation aqueous solution was cooled to 2-7℃, n-butyraldehyde was added, and concentrated hydrochloric acid was added dropwise. The mixture was stirred evenly, heated to 2-15℃, and the reaction was maintained for 2 hours. Then the temperature was raised to 10-25℃ and the reaction was maintained for 3.5 hours.

[0145] During the reaction, the transmittance of the reaction solution was measured at a wavelength of 600 nm. When the transmittance dropped to 80-85%, a compounded polymerization inhibitor A (triethylamine, triethanolamine, and phosphate buffer were added to deionized water in a mass ratio of 3:1:3 and stirred until homogeneous) was added dropwise to the reaction system. The mixture was stirred continuously for 12 minutes to cut off the acetalization process in the reaction system. Then, a compound polymerization inhibitor B was added dropwise to the reaction system and the mixture was stirred for 18 minutes to terminate the acetalization process in the reaction system, resulting in an all-aqueous polyvinyl butyral solution.

[0146] The steps for adding composite polymerization inhibitor B are as follows: First, add sodium bisulfite dropwise into the reaction system, stir evenly and continue the reaction for 6 minutes; then add polysorbate 80 dropwise into the reaction system, continue the reaction for 6 minutes, and finally add polyvinylpyrrolidone dropwise into the reaction system, stir evenly and continue the reaction for 6 minutes.

[0147] Experimental Example 5

[0148] An all-aqueous polyvinyl butyral solution comprises the following components, in parts by weight:

[0149] 450 parts PVA resin, 30 parts butyraldehyde, 10 parts hydrochloric acid, 150 parts deionized water, 10 parts degradation agent, 2.5 parts composite polymerization inhibitor A, 2.5 parts composite polymerization inhibitor B, and 1 part pH adjuster.

[0150] The degradation agent is hydrogen peroxide; the composite polymerization inhibitor A includes triethylamine, triethanolamine and a phosphate buffer pair; the phosphate buffer pair includes dipotassium hydrogen phosphate and potassium dihydrogen phosphate; the composite polymerization inhibitor B includes sodium bisulfite, polysorbate 80 and polyvinylpyrrolidone.

[0151] Includes the following steps:

[0152] Deionized water and PVA resin were stirred at 98°C until the PVA resin was completely dissolved to obtain a PVA aqueous solution.

[0153] The degradation agent was slowly added dropwise to the obtained PVA aqueous solution, and the viscosity was measured during the reaction until the viscosity dropped to 850. A PVA-degraded aqueous solution was obtained;

[0154] The obtained PVA degraded aqueous solution was cooled to 2-7℃, n-butyraldehyde was added, and concentrated hydrochloric acid was added dropwise. The mixture was stirred evenly, heated to 2-15℃, and the reaction was maintained for 2.5 hours. Then the temperature was raised to 10-25℃ and the reaction was maintained for 4 hours.

[0155] During the reaction, the transmittance of the reaction solution was measured at a wavelength of 600 nm. When the transmittance dropped to 80-85%, a compounded polymerization inhibitor A (triethylamine, triethanolamine, and phosphate buffer were added to deionized water in a mass ratio of 3:1:3 and stirred until homogeneous) was added dropwise to the reaction system. The mixture was stirred continuously for 15 minutes to cut off the acetalization process in the reaction system. Then, a compound polymerization inhibitor B was added dropwise to the reaction system and the mixture was stirred for 24 minutes to terminate the acetalization process in the reaction system, resulting in an all-aqueous polyvinyl butyral solution.

[0156] The steps for adding composite polymerization inhibitor B are as follows: first, add sodium bisulfite dropwise into the reaction system, stir evenly and continue the reaction for 8 minutes; then add polysorbate 80 dropwise into the reaction system, continue the reaction for 8 minutes, and finally add polyvinylpyrrolidone dropwise into the reaction system, stir evenly and continue the reaction for 8 minutes.

[0157] Comparative Example 1

[0158] An all-aqueous polyvinyl butyral solution comprises the following components, in parts by weight:

[0159] 380 parts PVA resin, 20 parts butyraldehyde, 5 parts hydrochloric acid, 100 parts deionized water, 2 parts degradation agent, 2 parts composite polymerization inhibitor A, and 0.5 parts pH adjuster;

[0160] The degradation agent is hydrogen peroxide; the composite polymerization inhibitor A includes triethylamine, triethanolamine and a phosphate buffer pair; the phosphate buffer pair includes dipotassium hydrogen phosphate and potassium dihydrogen phosphate.

[0161] Includes the following steps:

[0162] Deionized water and PVA resin are stirred at a temperature of 90-98℃ until the PVA resin is completely dissolved to obtain a PVA aqueous solution.

[0163] The degradation agent was slowly added dropwise to the obtained PVA aqueous solution, and the viscosity was measured during the reaction until the viscosity dropped to 750. A PVA-degraded aqueous solution was obtained;

[0164] Cool the obtained degraded PVA aqueous solution to 2-7℃, add n-butyraldehyde, and add concentrated hydrochloric acid dropwise. Stir well, raise the temperature to 2-15℃, maintain the reaction for 1.5 hours, and then raise the temperature to 10-25℃ and maintain the reaction for 3 hours.

[0165] During the reaction, the transmittance of the reaction solution was measured at a wavelength of 600 nm. When the transmittance dropped to 80-85%, the compounded polymerization inhibitor A (triethylamine, triethanolamine and phosphate buffer were added to deionized water in a mass ratio of 3:1:3 and stirred evenly to obtain the compound polymerization inhibitor A) was slowly added dropwise to the reaction system. The mixture was stirred continuously for 8-15 minutes to cut off the acetalization process in the reaction system.

[0166] The appearance of particles after the above preparation process indicates the failure of preparing an all-aqueous polyvinyl butyral solution.

[0167] Comparative Example 2

[0168] An all-aqueous polyvinyl butyral solution comprises the following components, in parts by weight:

[0169] 400 parts PVA resin, 20 parts butyraldehyde, 5 parts hydrochloric acid, 100 parts deionized water, 2 parts degradation agent, 1.5 parts composite polymerization inhibitor B, and 0.8 parts pH adjuster;

[0170] The degradation agent is hydrogen peroxide; the composite polymerization inhibitor B includes sodium bisulfite, polysorbate 80, and polyvinylpyrrolidone.

[0171] Includes the following steps:

[0172] Deionized water and PVA resin were stirred at 95°C until the PVA resin was completely dissolved to obtain a PVA aqueous solution.

[0173] The degradation agent was slowly added dropwise to the obtained PVA aqueous solution, and the viscosity was measured during the reaction until the viscosity dropped to 800. A PVA-degraded aqueous solution was obtained;

[0174] Cool the obtained degraded PVA aqueous solution to 2-7℃, add n-butyraldehyde, and add concentrated hydrochloric acid dropwise. Stir well, raise the temperature to 2-15℃, maintain the reaction for 2 hours, and then raise the temperature to 10-25℃ and maintain the reaction for 3 hours.

[0175] During the reaction, the transmittance of the reaction solution was measured at a wavelength of 600 nm. When the transmittance dropped to 80-85%, composite polymerization inhibitor B was slowly added dropwise to the reaction system, and the reaction was stirred for 15 minutes to terminate the acetalization in the reaction system.

[0176] The steps for adding composite polymerization inhibitor B are as follows: First, add sodium bisulfite to the reaction system, stir evenly and continue the reaction for 5 minutes; then add polysorbate 80 to the reaction system, continue the reaction for 5 minutes, and finally add polyvinylpyrrolidone to the reaction system, stir evenly and continue the reaction for 5 minutes.

[0177] The appearance of particles after the above preparation process indicates the failure of preparing an all-aqueous polyvinyl butyral solution.

[0178] Comparative Example 3

[0179] An all-aqueous polyvinyl butyral solution comprises the following components, in parts by weight:

[0180] 300 parts PVA resin, 20 parts butyraldehyde, 5 parts hydrochloric acid, 100 parts deionized water, 5 parts degradation agent, 2 parts composite polymerization inhibitor A, 2 parts composite polymerization inhibitor B, and 0.8 parts pH fine-tuning agent;

[0181] The degradation agent is hydrogen peroxide; the composite polymerization inhibitor A is triethylamine; and the composite polymerization inhibitor B is sodium bisulfite.

[0182] Includes the following steps:

[0183] Deionized water and PVA resin were stirred at 95°C until the PVA resin was completely dissolved to obtain a PVA aqueous solution.

[0184] The degradation agent was slowly added dropwise to the obtained PVA aqueous solution, and the viscosity was measured during the reaction until the viscosity dropped to 800. A PVA-degraded aqueous solution was obtained;

[0185] Cool the obtained degraded PVA aqueous solution to 2-7℃, add n-butyraldehyde, and add concentrated hydrochloric acid dropwise. Stir well, raise the temperature to 2-15℃, maintain the reaction for 2 hours, and then raise the temperature to 10-25℃ and maintain the reaction for 3 hours.

[0186] During the reaction, the transmittance of the reaction solution was measured at a wavelength of 600 nm. When the transmittance dropped to 80-85%, composite polymerization inhibitor A (triethylamine) was slowly added dropwise to the reaction system, and the mixture was stirred continuously for 8-15 minutes to cut off the acetalization process in the reaction system. Then, composite polymerization inhibitor B (sodium bisulfite) was slowly added dropwise to the reaction system, and the mixture was stirred for 10 minutes to terminate the acetalization process in the reaction system, thus obtaining an all-aqueous polyvinyl butyral solution.

[0187] The steps for adding composite polymerization inhibitor B are as follows: first, add sodium bisulfite dropwise into the reaction system, stir evenly, and continue the reaction for 5 minutes.

[0188] The aqueous polyvinyl butyral solution obtained from Comparative Document 3 was stored at 40°C, and its changes were observed. Precipitation appeared on the 20th day, indicating that the prepared product had poor stability and could not be used.

[0189] The difference between Comparative Example 1 and other experimental examples is that only a single composite polymerization inhibitor A was used. The difference between Comparative Example 2 and other experimental examples is that only a single composite polymerization inhibitor B was used. The difference between Comparative Example 3 and other experimental examples is that composite polymerization inhibitor A is triethylamine and composite polymerization inhibitor B is sodium bisulfite. Since neither Comparative Example 1 nor Comparative Example 2 could prepare a fully aqueous polyvinyl butyral solution, it was impossible to conduct experimental comparisons of product performance.

[0190] Experiments 1-5 and Comparative Example 3 were compared experimentally. The comparison included acetalization detection, 10% water-soluble turbidity detection, storage days at 25℃, and storage days at 40℃. The test results are shown in the table below:

[0191] acetalization degree 10% water-soluble turbidity Days of storage at 25℃ Days of storage at 40℃ Experimental Example 1 45% 4NTU 400 days 235 days Experiment Example 2 42% 2NTU 390 days 235 days Experimental Example 3 38% 2NTU 320 days 235 days Experiment Example 4 35% 3NTU 310 days 235 days Experimental Example 5 32% 4NTU 300 days 235 days Comparative Example 3 36% 4NTU 150 days 20 days

[0192] Through the experimental analysis of the above examples and comparative examples, it can be concluded that the aqueous polyvinyl butyral solution prepared by the present invention has good stability. In addition, by improving the formulation for preparing the aqueous polyvinyl butyral solution, the use of organic solvents is reduced, thereby reducing environmental pollution and harm to the human body. The formulation contains composite polymerization inhibitor A and composite polymerization inhibitor B, which play a key role in the preparation of the aqueous polyvinyl butyral solution, enabling it to control the degree of acetalization of the reaction, avoid particle agglomeration during the reaction, and thus maintain the degree of acetalization at 30-50%, thereby ensuring water solubility.

[0193] The optional embodiments of the present invention have been described in detail above. However, the embodiments of the present invention are not limited to the specific details in the above embodiments. Within the scope of the technical concept of the embodiments of the present invention, various simple modifications can be made to the technical solutions of the embodiments of the present invention, and these simple modifications all fall within the protection scope of the embodiments of the present invention.

[0194] 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.

[0195] 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 an all-aqueous polyvinyl butyral solution, characterized in that, Includes the following steps: Deionized water and PVA resin are stirred at a temperature of 90-98℃ until the PVA resin is completely dissolved to obtain a PVA aqueous solution. The degradation agent was slowly added dropwise to the obtained PVA aqueous solution, and the viscosity value was measured during the reaction until the viscosity dropped to 750-850 mPa·s, thus obtaining the degraded PVA aqueous solution. Cool the obtained degraded PVA aqueous solution to 2-7℃, add n-butyraldehyde, and dropwise add concentrated hydrochloric acid. Stir evenly, raise the temperature to 2-15℃, maintain the reaction for 1.5-2.5 hours, then raise the temperature to 10-25℃ and maintain the reaction for 2-4 hours. During the reaction, the transmittance of the reaction solution was measured at a wavelength of 600 nm. When the transmittance dropped to 80-85%, the compounded polymerization inhibitor A was slowly added dropwise to the reaction system, and the mixture was stirred continuously for 8-15 minutes to cut off the acetalization process in the reaction system. Then, the compound polymerization inhibitor B was slowly added dropwise to the reaction system, and the mixture was stirred for 6-24 minutes to terminate the acetalization process in the reaction system, resulting in an all-aqueous polyvinyl butyral solution. The composite polymerization inhibitor A comprises triethylamine, triethanolamine, and a phosphate buffer pair; The composite polymerization inhibitor B includes sodium bisulfite, polysorbate 80, and polyvinylpyrrolidone.

2. The preparation method according to claim 1, characterized in that, The mass ratio of the triethylamine, triethanolamine and phosphate buffer pair is 3:1:3; Triethylamine, triethanolamine, and phosphate buffer were added to deionized water in a certain mass ratio and stirred until homogeneous to obtain composite polymerization inhibitor A.

3. The preparation method according to claim 1, characterized in that, The steps for adding composite polymerization inhibitor B are as follows: first, add sodium bisulfite dropwise into the reaction system, stir evenly and continue the reaction for 2-8 minutes; then add polysorbate 80 dropwise into the reaction system, continue the reaction for 2-8 minutes, and finally add polyvinylpyrrolidone dropwise into the reaction system, stir evenly and continue the reaction for 2-8 minutes.

4. The preparation method according to claim 1, characterized in that, The amount of composite polymerization inhibitor B added is 8%-15% of the mass of butyraldehyde.

5. The preparation method according to claim 1, characterized in that, The process also includes adding composite polymerization inhibitor B, followed by adding a pH adjuster, which is a 20% triethylamine aqueous solution, to the reaction system. The addition is stopped when the pH value in the reaction system is maintained at 6.5-7.5, and the mixture is stirred continuously for 20-35 minutes to obtain an all-aqueous polyvinyl butyral solution.

6. The preparation method according to claim 1 further includes adding a hydrophilic modifier to the obtained aqueous polyvinyl butyral solution, wherein the amount of hydrophilic modifier added is 0.5-2% of the mass of the aqueous polyvinyl butyral solution.

7. The aqueous polyvinyl butyral solution prepared by the method according to any one of claims 1 to 6, wherein the degree of acetalization of the aqueous polyvinyl butyral solution is 30-50%, and the turbidity of the aqueous polyvinyl butyral solution with a solid content of 10% is ≤5 NTU at 25°C.

8. The all-aqueous polyvinyl butyral solution according to claim 7, characterized in that, Includes the following components, in parts by weight: 350-450 parts PVA resin, 10-30 parts butyraldehyde, 1-10 parts hydrochloric acid, 50-150 parts deionized water, 1-10 parts degradation agent, 0.5-2.5 parts composite polymerization inhibitor A, and 0.5-2.5 parts composite polymerization inhibitor B; The degradation agent is hydrogen peroxide; The composite polymerization inhibitor A comprises triethylamine, triethanolamine, and a phosphate buffer pair; The phosphate buffer pair includes dipotassium hydrogen phosphate and potassium dihydrogen phosphate; The composite polymerization inhibitor B includes sodium bisulfite, polysorbate 80, and polyvinylpyrrolidone.

9. The all-aqueous polyvinyl butyral solution according to claim 8, characterized in that, Includes the following components, in parts by weight: 400 parts PVA resin, 20 parts butyraldehyde, 5 parts hydrochloric acid, 100 parts deionized water, 5 parts degradation agent, 2 parts composite polymerization inhibitor A, and 2 parts composite polymerization inhibitor B; The degradation agent is hydrogen peroxide; The composite polymerization inhibitor A comprises triethylamine, triethanolamine, and a phosphate buffer pair; The phosphate buffer pair includes dipotassium hydrogen phosphate and potassium dihydrogen phosphate; The composite polymerization inhibitor B includes sodium bisulfite, polysorbate 80, and polyvinylpyrrolidone.

10. The application of the all-aqueous polyvinyl butyral solution according to claim 7 in the fields of inks and coatings.