A method for preparing a yellowing-resistant polyvinyl butyral resin

Abstract

This invention belongs to the field of PVB resin, specifically relating to a method for preparing a yellowing-resistant polyvinyl butyral resin. In the preparation of the polyvinyl butyral resin, this invention adopts a staged feeding process. In the first feeding stage, inorganic acid mist and a portion of n-butyral are added to obtain a first intermediate product. In the second feeding stage, an aqueous solution of organic acid and the remaining n-butyral are added to obtain a second intermediate product. Through optimization of the process steps and feeding sequence, the comprehensive properties of the obtained PVB resin, including yellowing resistance, light transmittance, and processability, are significantly improved.

Description

Technical Field

[0001] This invention belongs to the field of PVB resin, specifically relating to a method for preparing a yellowing-resistant polyvinyl butyral resin. Background Technology

[0002] Polyvinyl butyral (PVB) resin, as a high-performance polymer material, is mainly produced through the condensation reaction of polyvinyl alcohol (PVA) and n-butyral in an acidic environment. Currently, PVB resin demonstrates broad application potential in various industrial fields due to its high transparency, excellent cold and frost resistance, outstanding impact strength, high-efficiency UV resistance, and excellent sound and heat insulation properties. It also achieves good adhesion to a variety of materials such as metals, glass, wood, ceramics, and fibers.

[0003] Precipitation is currently the most common method for preparing PVB resin. It primarily involves the chemical reaction between PVA aqueous solution and n-butyraldehyde, causing PVB to slowly precipitate and form a precipitate, thus transforming the system from a homogeneous to a heterogeneous phase. Specific steps include dissolving PVA in water, reacting it with n-butyraldehyde under acidic conditions via an aldol condensation reaction to generate PVB precipitate, followed by alkali neutralization, washing, and drying to finally obtain the finished PVB product. Depending on the reaction temperature, precipitation is further subdivided into low-temperature and high-temperature methods. While the low-temperature method produces a milder and more uniform reaction, its production efficiency is relatively low; the high-temperature method is known for its high efficiency, but the uniformity of the reaction needs improvement. For example, patent document CN113429501B discloses a method for preparing PVB resin using a low-temperature method. However, both the low-temperature and high-temperature methods have their limitations, making it difficult to meet the production requirements of higher-performance PVB resins.

[0004] Yellowing resistance is a crucial indicator of PVB resin quality. Traditional methods often involve adding antioxidants to the raw materials to improve this resistance. However, some antioxidants, when added to PVB resin, may affect the transparency of the film product due to molecular structure or compatibility issues; furthermore, the addition of antioxidants increases production costs. Therefore, optimizing process conditions to prepare PVB resin with excellent yellowing resistance without using additional antioxidants has become a challenging technical problem. Summary of the Invention

[0005] This invention provides a method for preparing yellowing-resistant polyvinyl butyral resin, comprising:

[0006] S1. According to mass, mix 1000kg of pure water and 100-120kg of PVA, heat to dissolve, then cool, filter to remove residue, and obtain PVA adhesive solution;

[0007] S2. First, add the acidic reaction base liquid to the reactor. Then, feed all the PVA adhesive and 2.0-2.5 kg of n-butyraldehyde into the reactor in one go using a metering pump. At the same time, use an atomizing nozzle to add inorganic acid mist. Stir to obtain the first intermediate product.

[0008] S3. Then, using a metering pump, feed 1.0-1.35 kg of n-butyraldehyde into the first intermediate product, add 2-3 L of organic acid aqueous solution, stir, and obtain the second intermediate product;

[0009] S4. Add an emulsifier aqueous solution to the second intermediate product, stir, and then heat the reaction to obtain crude PVB.

[0010] S5. Wash the crude PVB with pure water, adjust the pH to alkaline with a pH adjuster, add plasticizer and wash with water to remove impurities, react for 1-3 hours, after the reaction is complete, wash with pure water until the conductivity is less than 10 μs / cm, dehydrate and dry to obtain the product.

[0011] Furthermore, the preparation method of the aforementioned yellowing-resistant polyvinyl butyral resin includes:

[0012] S1. By mass, mix 1000kg of pure water and 100-120kg of PVA, heat to 80-95℃ within 1-2 hours, dissolve for 3-5 hours, then cool to 25-35℃, filter to remove residue, and obtain PVA adhesive solution.

[0013] S2. First, add the acidic reaction base liquid to the reactor. Then, feed all the PVA adhesive and 2.0-2.5 kg of n-butyraldehyde into the reactor in one go using a metering pump. At the same time, use an atomizing nozzle to add inorganic acid mist. Stir at 100-300 rpm and 20-25℃ to obtain the first intermediate product.

[0014] S3. Then, using a metering pump, feed 1.0-1.35 kg of n-butyraldehyde into the first intermediate product, and add 2-3 L of organic acid aqueous solution. Stir at 100-300 rpm and 20-25°C to obtain the second intermediate product.

[0015] S4. Add an emulsifier aqueous solution to the second intermediate product, increase the speed to 1000-1200 rpm, keep warm and stir for 10-20 min, then heat to 60-80℃ and react for 2-3 h to obtain crude PVB.

[0016] S5. Wash the crude PVB product with pure water 1-3 times, adjust the pH to 10-11 with a pH adjuster, add plasticizer, wash with water to remove impurities, react for 1-3 hours, wash with pure water until the conductivity is less than 10 μs / cm after the reaction, and dehydrate and dry to obtain the product.

[0017] As an implementable example, the PVA has a degree of alcoholysis of 90-99% and a degree of polymerization of 1000-3000.

[0018] Furthermore, the PVA includes one or more of PVA1799, PVA2699, and PVA 0899.

[0019] Furthermore, the PVA has a degree of alcoholysis of 98-99% and a degree of polymerization of 1000-2000.

[0020] Furthermore, the PVA mentioned is PVA 1799, purchased from Inner Mongolia Shuangxin Environmental Protection Materials Co., Ltd.

[0021] The degree of hydrolysis is an indicator of the extent of the alcoholysis reaction in polyvinyl alcohol (PVA) molecules, primarily reflecting the ratio of hydroxyl (-OH) to acetyl (-COCH3) groups within the PVA molecule. In the preparation of polyvinyl butyral (PVB), the degree of hydrolysis significantly affects the product's solubility and rheological properties: a low degree of hydrolysis leads to a high acetyl content in the PVB resin, which not only reduces solubility but also negatively impacts viscosity and flowability, making it difficult to form a uniform film during processing. The degree of polymerization represents the number of repeating units in the PVA molecular chain, thus determining the length and molecular weight of the PVA molecule. In the PVB resin preparation process, the degree of polymerization has a certain influence on the product's viscosity, solubility, and processability. Specifically, an excessively high degree of polymerization leads to a significant increase in the viscosity of the PVB resin, which not only increases processing difficulty but may also weaken the product's solubility and film uniformity; conversely, while a low degree of polymerization improves processability and solubility, it may weaken the mechanical properties of the PVB resin. Therefore, the present invention preferably uses PVA with a degree of hydrolysis between 98% and 99% and a degree of polymerization between 1000 and 2000 as the raw material for preparing PVB film, so as to ensure that the obtained PVB resin has good mechanical properties.

[0022] As an example of an implementable solution, the acidic reaction substrate includes one of hydrochloric acid, sulfuric acid, nitric acid, and phosphoric acid.

[0023] As an feasible example, the mass concentration of the acidic reaction substrate is 0.1-0.5 wt%.

[0024] Furthermore, the acidic substrate is a 0.2 wt% hydrochloric acid aqueous solution with a pH of 1.8.

[0025] As an feasible example, the feed rate of the PVA adhesive is 1-3 kg / min, and the feed time is 30-60 min.

[0026] As an example of an implementable solution, the inorganic acid mist includes one of sulfuric acid, hydrochloric acid, nitric acid, and phosphoric acid.

[0027] Furthermore, the inorganic acid mist is a hydrochloric acid aqueous solution with a mass concentration of 0.2 wt%.

[0028] Furthermore, the feed rate of the inorganic acid mist is 0.1-0.5 kg / min, and the feed time is 10-30 min.

[0029] As an implementable example, the organic acid aqueous solution includes one of p-toluenesulfonic acid aqueous solution, formic acid aqueous solution, acetic acid aqueous solution, tartaric acid aqueous solution, benzoic acid aqueous solution, and salicylic acid aqueous solution.

[0030] Furthermore, the organic acid aqueous solution is a p-toluenesulfonic acid (PTSA) aqueous solution, and the mass concentration of PTSA is 10-25 wt%.

[0031] As an example of implementation, the raw materials for preparing the emulsifier aqueous solution include an emulsifier and water.

[0032] As an implementable example, the emulsifier includes one or more of sodium stearate, sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, and sodium fatty alcohol sulfate.

[0033] Furthermore, the emulsifier is sodium dodecyl sulfate.

[0034] Furthermore, the mass concentration of the emulsifier in the aqueous solution is 10-25 wt%.

[0035] As an implementable example, the plasticizer includes one or more of dibutyl sebacate, dioctyl phthalate, dioctyl sebacate, dioctyl adipate, dibutyl phthalate, and dioctyl phthalate.

[0036] Furthermore, the plasticizer is dibutyl sebacate.

[0037] Beneficial effects

[0038] (i) In the initial feeding stage S2 of PVB preparation, 2.0-2.5 kg of n-butyraldehyde (more preferably 60-70% of the total n-butyraldehyde) is added to the reaction system first. This can ensure that the acetalization reaction is more uniform and the degree of acetalization is more balanced during the reaction process. This effectively reduces the difference in acetalization distribution and helps to improve the performance stability and consistency of the final product.

[0039] (ii) In the S3 step reaction, adding organic acid and the remaining butyraldehyde (1.0-1.35 kg, more preferably 30-35% of the total butyraldehyde) can rapidly bring the reaction of the subsequent feed materials to a degree of acetalization consistent with the overall reaction. Simultaneously, increasing the amount of organic acid promotes a uniform increase in the degree of acetalization of all PVB resins, approaching the theoretical design value. This not only improves reaction efficiency but also ensures that the final product's degree of acetalization meets the expected requirements, and that the PVB resin exhibits high resistance to yellowing.

[0040] (III) During the preparation process, inorganic ionic acids mainly remain in the first stage of the S2 step system. These inorganic ionic acids can be effectively removed during the water washing stage due to the effect of internal and external osmotic pressure. However, when organic acids are added in the S3 step, crystal nuclei have already formed. Although the organic acids are relatively difficult to wash away at this point, they are mainly present on the outer surface of the resin and are therefore easier to remove in subsequent processing compared to when introduced at the beginning of the reaction. This effectively reduces the impact of inorganic ionic acids and organic acids on the final product.

[0041] (iv) In step S2 of this invention, hydrochloric acid is added by atomization and combined with a negative pressure vacuum vortex formed by high-speed stirring, which can effectively disperse it into the reaction system, avoiding the difference in PVB resin particle size caused by excessive local concentration, thereby ensuring the stability and consistency of the resin and its resistance to yellowing, which has a significant impact on improving the quality and performance stability of the final product.

[0042] (V) In this invention, since all corrosive materials are added and processed in the reaction vessel, the maintenance pressure on the front-end equipment is greatly reduced. This not only extends the service life of the equipment but also reduces production interruptions and losses caused by equipment failures. At the same time, it improves the safety and stability of the production process, providing a strong guarantee for the company's continuous production and development. Detailed Implementation

[0043] Example 1

[0044] This example provides a method for preparing yellowing-resistant polyvinyl butyral resin, specifically as follows:

[0045] S1. By mass, mix 1000kg of pure water at 30℃ and 100kg of PVA 1799. Stir at 100rpm during the mixing process, raise the temperature to 90℃ within 1 hour, dissolve for 3 hours, then cool down to 30℃, filter to remove residue, and obtain PVA adhesive solution.

[0046] S2. First, add 20L of 0.2wt% hydrochloric acid aqueous solution with pH=1.8 to a 200L reactor. Then, feed all the PVA adhesive and 2.3kg of n-butyraldehyde into the reactor in one go using a metering pump. The feed rate of the PVA adhesive is 2kg / min and the feed time is 30min. At the same time, feed 0.2wt% hydrochloric acid mist using an atomizing nozzle. The feed time of the hydrochloric acid mist is 10min and the feed rate is 0.2kg / min. Then, stir at 200rpm and 20℃ to obtain the first intermediate product.

[0047] S3. Then, using a metering pump, feed 1.13 kg of n-butyraldehyde into the first intermediate product, and add 2 L of 10 wt% PTSA aqueous solution. Stir at 300 rpm and 25°C to obtain the second intermediate product.

[0048] S4. Add 0.2L of 10wt% sodium dodecyl sulfate aqueous solution to the second intermediate product, increase the speed to 1000rpm, keep warm and stir for 10min, then heat to 75℃ and react for 2h to obtain crude PVB.

[0049] S5. Wash the crude PVB twice with pure water, then adjust the pH to 10-11 with 5wt% sodium hydroxide aqueous solution, add 1.2kg of dibutyl sebacate, wash with water to remove impurities, react for 2 hours, after the reaction is complete, wash with pure water until the conductivity of the product is less than 10μs / cm, and then dehydrate and dry to obtain the product.

[0050] Example 2

[0051] This example provides a method for preparing yellowing-resistant polyvinyl butyral resin, specifically as follows:

[0052] S1. By mass, mix 1000kg of pure water at 30℃ and 100kg of PVA 1799. Stir at 100rpm during the mixing process, raise the temperature to 90℃ within 1 hour, dissolve for 3 hours, then cool down to 30℃, filter to remove residue, and obtain PVA adhesive solution.

[0053] S2. First, add 20L of 0.2wt% hydrochloric acid aqueous solution with pH=1.8 to a 200L reactor. Then, feed all the PVA adhesive and 2.32kg of n-butyraldehyde into the reactor in one go using a metering pump. The feed rate of the PVA adhesive is 2kg / min and the feed time is 30min. At the same time, feed 0.2wt% hydrochloric acid mist using an atomizing nozzle. The feed time of the hydrochloric acid mist is 10min and the feed rate is 0.2kg / min. Then, stir at 200rpm and 20℃ to obtain the first intermediate product.

[0054] S3. Then, using a metering pump, feed 1.14 kg of n-butyraldehyde into the first intermediate product, and add 2 L of 10 wt% PTSA aqueous solution. Stir at 300 rpm and 25°C to obtain the second intermediate product.

[0055] S4. Add 0.2L of 10wt% sodium dodecyl sulfate aqueous solution to the second intermediate product, increase the speed to 1000rpm, keep warm and stir for 10min, then heat to 80℃ and react for 2h to obtain crude PVB.

[0056] S5. Wash the crude PVB twice with pure water, then adjust the pH to 10-11 with 5wt% sodium hydroxide aqueous solution, add 1.2kg of dibutyl sebacate, wash with water to remove impurities, react for 2 hours, after the reaction is complete, wash with pure water until the conductivity of the product is less than 10μs / cm, and then dehydrate and dry to obtain the product.

[0057] Example 3

[0058] This example provides a method for preparing yellowing-resistant polyvinyl butyral resin, specifically as follows:

[0059] S1. By mass, mix 1000kg of pure water at 30℃ and 100kg of PVA 1799. Stir at 100rpm during the mixing process, raise the temperature to 90℃ within 1 hour, dissolve for 3 hours, then cool down to 30℃, filter to remove residue, and obtain PVA adhesive solution.

[0060] S2. First, add 20L of 0.2wt% hydrochloric acid aqueous solution with pH=1.8 to a 200L reactor. Then, feed all the PVA adhesive and 2.3kg of n-butyraldehyde into the reactor in one go using a metering pump. The feed rate of the PVA adhesive is 2kg / min and the feed time is 30min. At the same time, feed 0.2wt% hydrochloric acid mist using an atomizing nozzle. The feed time of the hydrochloric acid mist is 10min and the feed rate is 0.2kg / min. Then, stir at 200rpm and 20℃ to obtain the first intermediate product.

[0061] S3. Then, using a metering pump, feed 1.16 kg of n-butyraldehyde into the first intermediate product, and add 2 L of 10 wt% PTSA aqueous solution. Stir at 300 rpm and 25°C to obtain the second intermediate product.

[0062] S4. Add 0.2L of 10wt% sodium dodecyl sulfate aqueous solution to the first intermediate product, increase the speed to 1000rpm, keep warm and stir for 10min, then heat to 75℃ and react for 2h to obtain crude PVB.

[0063] S5. Wash the crude PVB twice with pure water, then adjust the pH to 10-11 with 5wt% sodium hydroxide aqueous solution, add 1.2kg of dibutyl sebacate, wash with water to remove impurities, react for 2 hours, after the reaction is complete, wash with pure water until the conductivity of the product is less than 10μs / cm, and then dehydrate and dry to obtain the product.

[0064] Example 4

[0065] This example provides a method for preparing yellowing-resistant polyvinyl butyral resin, specifically as follows:

[0066] S1. By mass, mix 1000kg of pure water at 30℃ and 100kg of PVA 1799. Stir at 100rpm during the mixing process, raise the temperature to 90℃ within 1 hour, dissolve for 3 hours, then cool down to 30℃, filter to remove residue, and obtain PVA adhesive solution.

[0067] S2. First, add 20L of 0.2wt% hydrochloric acid aqueous solution with pH=1.8 to a 200L reactor. Then, feed all the PVA adhesive and 2.3kg of n-butyraldehyde into the reactor in one go using a metering pump. The feed rate of the PVA adhesive is 2kg / min and the feed time is 30min. At the same time, feed 0.2wt% hydrochloric acid mist using an atomizing nozzle. The feed time of the hydrochloric acid mist is 10min and the feed rate is 0.2kg / min. Then, stir at 200rpm and 20℃ to obtain the first intermediate product.

[0068] S3. Then, using a metering pump, feed 1.2 kg of n-butyraldehyde into the first intermediate product, and add 2 L of 10 wt% PTSA aqueous solution. Stir at 300 rpm and 25°C to obtain the second intermediate product.

[0069] S4. Add 0.2L of 10wt% sodium dodecyl sulfate aqueous solution to the second intermediate product, increase the speed to 1000rpm, keep warm and stir for 10min, then heat to 75℃ and react for 2h to obtain crude PVB.

[0070] S5. Wash the crude PVB twice with pure water, then adjust the pH to 10-11 with 5wt% sodium hydroxide aqueous solution, add 1.2kg of dibutyl sebacate, wash with water to remove impurities, react for 2 hours, after the reaction is complete, wash with pure water until the conductivity of the product is less than 10μs / cm, and then dehydrate and dry to obtain the product.

[0071] Comparative Example 1

[0072] This example provides a method for preparing polyvinyl butyral resin, specifically as follows:

[0073] S1. By mass, mix 1000kg of pure water at 30℃ and 100kg of PVA 1799. Stir at 100rpm during the mixing process, raise the temperature to 90℃ within 1 hour, dissolve for 3 hours, then cool down to 30℃, filter to remove residue, and obtain PVA adhesive solution.

[0074] S2. First, add 20L of 0.2wt% hydrochloric acid aqueous solution with pH=1.8 to a 200L reactor. Then, feed all the PVA adhesive and 2.3kg of n-butyraldehyde into the reactor in one go using a metering pump. The feed rate of the PVA adhesive is 2kg / min and the feed time is 30min. At the same time, add 2L of 10wt% PTSA aqueous solution. Then, stir at 200rpm and 20℃ to obtain the first intermediate product.

[0075] S3. Then, using a metering pump, 1.13 kg of n-butyraldehyde is fed into the first intermediate product, and 0.2 wt% hydrochloric acid mist is fed into the product using an atomizing nozzle. The feeding time of the hydrochloric acid mist is 10 min, and the feeding rate is 0.2 kg / min. Then, the mixture is stirred at 300 rpm and 25°C to obtain the second intermediate product.

[0076] S4. Add 0.2L of 10wt% sodium dodecyl sulfate aqueous solution to the second intermediate product, increase the speed to 1000rpm, keep warm and stir for 10min, then heat to 75℃ and react for 2h to obtain crude PVB.

[0077] S5. Wash the crude PVB twice with pure water, then adjust the pH to 10-11 with 5wt% sodium hydroxide aqueous solution, add 1.2kg of dibutyl sebacate, wash with water to remove impurities, react for 2 hours, after the reaction is complete, wash with pure water until the conductivity of the product is less than 10μs / cm, and then dehydrate and dry to obtain the product.

[0078] Comparative Example 2

[0079] This example provides a method for preparing polyvinyl butyral resin, specifically as follows:

[0080] S1. By mass, mix 1000kg of pure water at 30℃ and 100kg of PVA1799. Stir at 100rpm during the mixing process, raise the temperature to 90℃ within 1 hour, dissolve for 3 hours, then cool down to 30℃, filter to remove residue, and obtain PVA adhesive solution.

[0081] S2. First, add 20L of 0.2wt% hydrochloric acid aqueous solution with pH=1.8 to a 200L reactor. Then, feed all the PVA adhesive and 2.3kg of n-butyraldehyde into the reactor in one go using a metering pump. The feed rate of the PVA adhesive is 2kg / min and the feed time is 30min. At the same time, add 2L of 10wt% PTSA aqueous solution. Then, stir at 200rpm and 20℃ to obtain the first intermediate product.

[0082] S3. Then, using a metering pump, feed 1.13 kg of n-butyraldehyde into the first intermediate product, and add 2 L of 10 wt% PTSA aqueous solution. Stir at 300 rpm and 25°C to obtain the second intermediate product.

[0083] S4. Add 0.2L of 10wt% sodium dodecyl sulfate aqueous solution to the second intermediate product, increase the speed to 1000rpm, keep warm and stir for 10min, then heat to 75℃ and react for 2h to obtain crude PVB.

[0084] S5. Wash the crude PVB twice with pure water, then adjust the pH to 10-11 with 5wt% sodium hydroxide aqueous solution, add 1.2kg of dibutyl sebacate, wash with water to remove impurities, react for 2 hours, after the reaction is complete, wash with pure water until the conductivity of the product is less than 10μs / cm, and then dehydrate and dry to obtain the product.

[0085] In Examples 1-4 and Comparative Examples 1-2, PVA1799 was purchased from Inner Mongolia Shuangxin Environmental Protection Materials Co., Ltd., and other raw materials were ordinary commercially available products.

[0086] Performance Evaluation

[0087] Test subjects: Polyvinyl butyral prepared in Examples 1-4 and Comparative Examples 1-2; Test items and methods are as follows, and test results are detailed in Table 1.

[0088] 1. Hydroxyl value test method

[0089] Accurately weigh 1 g of polyvinyl butyral (to a minimum of 0.1 mg) and place it in a 250 mL ground-glass stoppered Erlenmeyer flask. Accurately add 10 mL of a pyridine-acetic anhydride mixture (9 mL pyridine + 1 mL acetic anhydride). Attach a condenser to the Erlenmeyer flask and heat to 95 °C under reflux for 3 hours until the sample is completely dissolved. Cool to room temperature, add 25 mL of 1,2-dichloroethane through the top of the condenser, remove the condenser, stopper the flask, and gently shake to mix.

[0090] Add 5 mL of distilled water to wash the stopper and walls of the flask, gently shake to mix, and let stand for 1 hour. Use a pipette to transfer distilled water along the walls of the conical flask to rinse, and add approximately 2 mL of phenolphthalein indicator. Titrate with 0.5 mol / L sodium hydroxide standard solution until the solution turns red, which is the endpoint. Perform a blank experiment simultaneously.

[0091] Formula for calculating hydroxyl content

[0092]

[0093] In the formula: X -- percentage of hydroxyl content, %.

[0094] Vb -- The volume of sodium hydroxide solution used in the blank test, in mL;

[0095] Vs -- The volume of sodium hydroxide solution used in the sample test, in mL;

[0096] C -- Molar concentration of sodium hydroxide solution, mol / L;

[0097] M -- Mass of the sample, in grams;

[0098] H -- Volatile content of the sample, %.

[0099] The difference between the two values ​​of the parallel test results should not exceed 0.3%.

[0100] 2. Viscosity test

[0101] Place the sample (>15g) in an oven (60±1℃) and bake for 5 hours. Remove and cool in a desiccator for later use. Weigh 133±0.1g of ethanol for later use. Add approximately half the amount of ethanol to a clean, dry 250mL three-necked flask (with a stirrer). While stirring, add the remaining ethanol to the flask. Turn on the power and heat (50±2℃) to dissolve the ethanol completely. After cooling, weigh the solution. If solvent is lost, replenish the solvent to accurately prepare a 5% n-butanol solution.

[0102] Take 200 mL of the prepared ethanol solution, with the sample temperature at 30 °C, place it on a viscometer for testing, and record the test results.

[0103] 3. Light transmittance test

[0104] Polyvinyl butyral and plasticizer 3GO (triethylene glycol diisooctanoate) were mixed at a mass ratio of 3:1 to obtain a PVB film. The PVB film samples were cut to size of 50mm x 60mm, and the number of samples was 3 pieces. The process was carried out in accordance with the provisions of GB / T 2410-2008.

[0105] 4. Haze Test

[0106] Polyvinyl butyral and plasticizer 3GO (triethylene glycol diisooctanoate) were mixed at a mass ratio of 3:1 to obtain a PVB film. The PVB film samples were cut to size of 50mm x 60mm, and the number of samples was 3 pieces. The process was carried out in accordance with the provisions of GB / T 2410-2008.

[0107] 5. Yellow Index

[0108] This includes the yellow index before aging and the yellow index after material aging. The aging conditions are: 180℃, 2h; carried out in accordance with the provisions of HG / T 3862-2006.

[0109] Table 1

[0110]

[0111]

[0112] The experimental results from Examples 1-4 and Comparative Examples 1-2 show that, in the preparation of polyvinyl butyral, adding 60-70% of the total amount of inorganic acid mist and n-butyral first, followed by the addition of an aqueous organic acid solution and the remaining n-butyral, can effectively improve the overall performance of PVB resin, including its resistance to yellowing, light transmittance, and haze. The overall performance of the product is significantly improved.

Claims

1. A method for preparing a yellowing-resistant polyvinyl butyral resin, characterized in that, include: S1. According to mass, mix 1000kg of pure water and 100-120kg of PVA, heat to dissolve, then cool, filter to remove residue, and obtain PVA adhesive solution; S2. First, add the acidic reaction base liquid to the reactor. Then, feed all the PVA adhesive and 2.0-2.5 kg of n-butyraldehyde into the reactor in one go using a metering pump. At the same time, use an atomizing nozzle to add inorganic acid mist. Stir to obtain the first intermediate product. S3. Then, using a metering pump, feed 1.0-1.35 kg of n-butyraldehyde into the first intermediate product, add 2-3 L of organic acid aqueous solution, stir, and obtain the second intermediate product; S4. Add an emulsifier aqueous solution to the second intermediate product, stir, and then heat the reaction to obtain crude PVB. S5. Wash the crude PVB with pure water, adjust the pH to alkaline with a pH adjuster, add plasticizer and wash with water to remove impurities, react for 1-3 hours, after the reaction is complete, wash with pure water until the conductivity is less than 10 μs / cm, dehydrate and dry to obtain the product.

2. The method for preparing the yellowing-resistant polyvinyl butyral resin according to claim 1, characterized in that, include: S1. By mass, mix 1000kg of pure water and 100-120kg of PVA, heat to 80-95℃ within 1-2 hours, dissolve for 3-5 hours, then cool to 25-35℃, filter to remove residue, and obtain PVA adhesive solution. S2. First, add the acidic reaction base liquid to the reactor. Then, feed all the PVA adhesive and 2.0-2.5 kg of n-butyraldehyde into the reactor in one go using a metering pump. At the same time, use an atomizing nozzle to add inorganic acid mist. Stir at 100-300 rpm and 20-25℃ to obtain the first intermediate product. S3. Then, using a metering pump, feed 1.0-1.35 kg of n-butyraldehyde into the first intermediate product, and add 2-3 L of organic acid aqueous solution. Stir at 100-300 rpm and 20-25°C to obtain the second intermediate product. S4. Add an emulsifier aqueous solution to the second intermediate product, increase the speed to 1000-1200 rpm, keep warm and stir for 10-20 min, then heat to 60-80℃ and react for 2-3 h to obtain crude PVB. S5. Wash the crude PVB product with pure water 1-3 times, adjust the pH to 10-11 with a pH adjuster, add plasticizer, wash with water to remove impurities, react for 1-3 hours, wash with pure water until the conductivity is less than 10 μs / cm after the reaction, and dehydrate and dry to obtain the product.

3. The method for preparing the yellowing-resistant polyvinyl butyral resin according to claim 1, characterized in that, The PVA has a degree of alcoholysis of 90-99% and a degree of polymerization of 1000-3000.

4. The method for preparing the yellowing-resistant polyvinyl butyral resin according to claim 1, characterized in that, The acidic reaction substrate includes one of hydrochloric acid, sulfuric acid, nitric acid, and phosphoric acid.

5. The method for preparing the yellowing-resistant polyvinyl butyral resin according to claim 4, characterized in that, The mass concentration of the acidic reaction substrate is 0.1-0.5 wt%.

6. The method for preparing the yellowing-resistant polyvinyl butyral resin according to claim 1, characterized in that, The feed rate of the PVA adhesive solution is 1-3 kg / min, and the feed time is 30-60 min.

7. The method for preparing the yellowing-resistant polyvinyl butyral resin according to any one of claims 1-6, characterized in that, The inorganic acid mist includes one of sulfuric acid, hydrochloric acid, nitric acid, and phosphoric acid.

8. The method for preparing the yellowing-resistant polyvinyl butyral resin according to claim 7, characterized in that, The feed rate of the inorganic acid mist is 0.1-0.5 kg / min, and the feed time is 10-30 min.

9. The method for preparing the yellowing-resistant polyvinyl butyral resin according to claim 1, characterized in that, The organic acid aqueous solution includes one of the following: p-toluenesulfonic acid aqueous solution, formic acid aqueous solution, acetic acid aqueous solution, tartaric acid aqueous solution, benzoic acid aqueous solution, and salicylic acid aqueous solution.

10. The method for preparing the yellowing-resistant polyvinyl butyral resin according to claim 1, characterized in that, The raw materials for the emulsifier aqueous solution include emulsifier and water; The emulsifier includes one or more of sodium stearate, sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, and sodium fatty alcohol sulfate.

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