Heat-resistant polyvinyl acetal resin and method for producing the same

Abstract

The present application relates to polyvinyl acetal resin preparation technical field, especially to IPC C08F8 field, further, a kind of heat aging resistant polyvinyl acetal resin and preparation method thereof.It includes by weight parts: polyvinyl alcohol 100 parts, aldehyde 50~70 parts, organic acid 10~70 parts, hydrochloric acid 2~5 parts, mixed solvent 500~2000 parts;The mixed solvent is the aqueous solution of organic solvent.The heat aging resistant polyvinyl acetal resin prepared by the present application has significantly improved heat aging resistant performance, and the acetalization rate and butyraldehyde utilization rate of the obtained resin are not less than hydrochloric acid catalysis, when used for intermediate film or packaging material, it has higher light transmittance, sun resistance, weather resistance and heat resistance.

Description

Technical Field

[0001] This invention relates to the field of polyvinyl acetal resin preparation technology, particularly to the field of IPC C08F8, and further to a heat-resistant aging polyvinyl acetal resin and its preparation method. Background Technology

[0002] It possesses excellent optical properties and good safety performance. Furthermore, because polyvinyl acetal resin is obtained by the condensation of polyvinyl alcohol and aldehyde, the resulting cyclic and branched structures give it both good flexibility and extremely strong adhesive properties, which is beneficial for improving its mechanical properties and enhancing its aging resistance. Currently, polyvinyl acetal resin is widely used in the automotive, construction, aerospace, solar photovoltaic modules, and daily consumer (coatings, inks) industries.

[0003] There are homogeneous and heterogeneous methods for preparing polyvinyl alcohol acetal resin. The heterogeneous method starts with polyvinyl alcohol (PVA) to form an aqueous PVA solution, adds aldehyde and acidic catalyst, reacts at a certain temperature to precipitate powder, and finally washes and dries it. Because this method is relatively simple to operate and the post-processing is simple, it has become the mainstream in the industry.

[0004] However, the heterogeneous production process often uses hydrochloric acid or other strong acids as catalysts. This has drawbacks, such as the strong acidity making it difficult to control and causing corrosion to pipes and equipment. Furthermore, as the acetalization reaction proceeds, the semi-acetalized resin begins to precipitate from the water, reducing the catalytic effect of the hydrochloric acid. This can slow down the reaction and cause it to become less uniform, resulting in an uneven degree of acetalization in the final product and affecting its quality. To address these issues, Chinese patent CN… Method 202011644464 discloses a method for preparing polyvinyl acetal resin and its application. The method involves: S10, dissolving polyvinyl alcohol and an acidic catalyst in pure water, stirring thoroughly to form a mixed solution, and cooling the mixed solution to below 20°C; S20, adding polyvinyl acetal raw materials, emulsifiers, and aldehydes to the cooled mixed solution, and stirring at 30–70°C for 1.5–5 hours to obtain mixed solution A; S30, adding sodium hydroxide solution to mixed solution A to terminate the reaction, resulting in a suspension containing solids; S40, removing impurities from the suspension, separating the solid and liquid phases, and washing and drying the obtained solids to obtain polyvinyl acetal resin. This method improves the average degree of acetalization by adding emulsifiers to refine the particles. However, residual acids and their salts, as well as emulsifiers, in the final product are difficult to remove due to their small molecular size, directly affecting product quality, especially reducing the product's optical properties and aging resistance. Summary of the Invention

[0005] To solve the above-mentioned technical problems, the first aspect of the present invention provides a heat-resistant aging polyvinyl alcohol acetal resin, which, by weight, comprises: 100 parts of polyvinyl alcohol, 50-70 parts of aldehyde, 10-70 parts of organic acid, 2-5 parts of hydrochloric acid, and 500-2000 parts of mixed solvent; wherein the mixed solvent is an aqueous solution of an organic solvent.

[0006] Preferably, the polyvinyl alcohol has an average degree of polymerization of 400–3000 and a degree of alcoholysis of 80–99%.

[0007] Preferably, the polyvinyl alcohol has an average degree of polymerization of 1000-2000 and a degree of alcoholysis of 80-99%.

[0008] Preferably, the polyvinyl alcohol has an average degree of polymerization of 1700 and a degree of alcoholysis of 99%.

[0009] Preferably, the aldehyde is at least one of C1-C10 aliphatic aldehydes and C7-C10 aromatic aldehydes.

[0010] Preferably, the aldehyde is a C1-C10 aliphatic aldehyde.

[0011] Preferably, the aldehyde is a C1-C6 aliphatic aldehyde.

[0012] Preferably, the C1 to C6 aliphatic aldehydes are selected from any one of formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde, pentanaldehyde, and hexanal.

[0013] Preferably, the aldehyde is butyraldehyde.

[0014] Preferably, the weight ratio of hydrochloric acid to organic acid is 3:(10-70).

[0015] Preferably, the weight ratio of hydrochloric acid to organic acid is 3:(10-50).

[0016] Preferably, the organic acid is an aqueous solution of an organic acid.

[0017] Preferably, the organic acid in the aqueous solution has a mass concentration of 15-30 wt%.

[0018] Preferably, the organic acid in the aqueous solution has a mass concentration of 20 wt%.

[0019] Preferably, the organic acid is a natural organic acid.

[0020] Preferably, the natural organic acid is a component of fruits or vegetables.

[0021] Preferably, the natural organic acid is selected from any one of citric acid, sorbic acid, acetic acid, succinic acid, tartaric acid, oxalic acid, and malic acid.

[0022] Preferably, the natural organic acid is citric acid.

[0023] During their research, the inventors discovered that when most of the hydrochloric acid was replaced with organic acid, and the weight ratio of hydrochloric acid to organic acid was controlled at 3:(10-70), especially when the weight ratio was 3:(10-50), polyvinyl alcohol acetal resin with high acetal degree and high aldehyde utilization rate could be obtained at lower acidity (pH between 3.0 and 5.0) (previous technologies mostly use pH between 2.0 and 3.0), comparable to that obtained using strong acid (hydrochloric acid) as a catalyst. Simultaneously, the inventors also unexpectedly discovered that the technical solution of this invention significantly improved the heat aging resistance of polyvinyl alcohol acetal resin compared to that prepared using only hydrochloric acid as a catalyst. This indicates that the polyvinyl alcohol acetal resin prepared by the technical solution of this invention contains fewer residual impurities, especially less residual acid, thus avoiding premature molecular chain breakage and decomposition of the polyvinyl alcohol acetal resin at high temperatures due to the presence of impurities.

[0024] Preferably, the organic solvent is selected from at least one of monohydric alcohols, polyhydric alcohols, acetone, and cyclohexanone.

[0025] Preferably, the monohydric alcohol is selected from any one of methanol, ethanol, and propanol.

[0026] Preferably, the polyol is selected from any one of ethylene glycol, propylene glycol, and glycerol.

[0027] Preferably, the mass concentration of the organic solvent in the aqueous solution is 0.1 to 15 wt%.

[0028] Preferably, the weight ratio of the organic acid to the mixed solvent is 1:(35-70).

[0029] In existing technologies, polyvinyl alcohol is often dissolved in water and condensed with aldehydes. However, as the reaction time increases, the solubility of polyvinyl alcohol acetal resin decreases due to the reduction in the number of hydrogen bonds in the system. This leads to the product entanglement with the catalyst or shielding of unreacted polyvinyl alcohol, resulting in a decrease in the acetal yield.

[0030] During their research, the inventors discovered that when the mixed solvent of this invention is an aqueous solution of an organic solvent, and the organic solvent is at least one of a monohydric alcohol, a polyhydric alcohol, acetone, or cyclohexanone, it not only increases the acetalization rate of polyvinyl alcohol acetal resin but also improves its heat aging resistance. The inventors speculate that this is because the mixed solvent of this invention has good permeability and strong dissolving power for polyvinyl alcohol and aldehydes during the condensation process, improving the uniformity of the dispersion of raw materials in the system. This allows the reaction to proceed smoothly even when most of the hydrochloric acid is replaced with organic acids (in a lower acidic environment). Simultaneously, the inventors found that the use of the mixed solvent makes the reaction more controllable. By precisely controlling the temperature, while improving the acetalization rate and the uniformity of the system viscosity, the amount of acid used can be further reduced, lowering costs. The mixed solvent after the reaction is complete can be reused after filtration and separation.

[0031] The second aspect of this invention provides a method for preparing heat-resistant aging polyvinyl alcohol acetal resin, comprising the following steps: adding polyvinyl alcohol to a mixed solvent, mixing evenly at 85℃~95℃, filtering, adding hydrochloric acid and organic acid and mixing evenly, cooling, adding aldehyde dropwise to react, and obtaining a reaction solution of granular resin; adding sodium hydroxide solution to the reaction solution to neutralize, finally making the pH of the reaction solution = 10, and then sequentially filtering, washing with deionized water, and drying to obtain the resin.

[0032] Preferably, the temperature after cooling is below 10°C.

[0033] Preferably, the temperature after cooling is 8±1℃.

[0034] Preferably, the conditions for the reaction of adding aldehyde dropwise are: maintaining the cooling temperature for 20-40 minutes and then raising the temperature, maintaining the raised temperature for 2.5-3.5 hours.

[0035] Preferably, the temperature after heating is above 50°C.

[0036] Preferably, the temperature after heating is 60±1℃.

[0037] Beneficial effects:

[0038] 1. In this invention, by replacing most of the hydrochloric acid with organic acid and controlling the weight ratio of hydrochloric acid to organic acid to be 3:(10-70), especially when the weight ratio of hydrochloric acid to organic acid is 3:(10-50), polyvinyl alcohol acetal resin with high acetal degree and high aldehyde utilization rate can be obtained under lower acidity (pH between 3.0 and 5.0) (most existing technologies use pH between 2.0 and 3.0). At the same time, the inventors also unexpectedly discovered that the technical solution of this invention significantly improves the heat aging resistance of polyvinyl alcohol acetal resin compared to that prepared using only hydrochloric acid as a catalyst.

[0039] 2. The mixed solvent of the present invention has good permeability and strong solubility for polyvinyl alcohol and aldehyde during the condensation process of polyvinyl alcohol and aldehyde, which improves the uniformity of the dispersion of raw materials in the system. As a result, the reaction can proceed smoothly when most of the hydrochloric acid is replaced by organic acid (in a lower acidic environment).

[0040] 3. Due to the use of mixed solvents, the reaction is more controllable in this invention. By precisely controlling the temperature, the acetal rate and system viscosity uniformity can be improved, while the amount of acid used can be further reduced, thus lowering the cost. The mixed solvent can be reused after filtration and separation after the reaction is completed.

[0041] 4. This invention uses a mixed solvent and organic acid, which can produce a product powder with high acetal degree, aldehyde utilization rate and excellent heat aging resistance under low acidity conditions. It also greatly reduces the amount of alkali solution used, which objectively reduces the amount of salt generated. This reduces the number of washing cycles and saves a lot of washing water, while also improving the degree of acetalization and distribution uniformity, thereby obtaining a resin material with stronger heat aging resistance and better light transmittance.

[0042] 5. This invention ensures the catalytic ability of organic acids by using mixed solvents and reducing the amount of hydrochloric acid. Moreover, the organic acids are naturally extracted, basically non-toxic and harmless, and can be naturally degraded after discharge, without polluting the environment at all.

[0043] 6. The raw materials provided by this invention are simple and the preparation method is convenient, which is conducive to improving the production efficiency and product quality of polyvinyl acetal resin and promoting the mass production of polyvinyl alcohol acetal resin. Detailed Implementation

[0044] Example 1

[0045] Example 1 provides a heat-resistant aging polyvinyl butyral resin, which, by weight, comprises: 100 parts polyvinyl alcohol, 60 parts butyral, 10 parts organic acid, 3 parts hydrochloric acid, and 500 parts mixed solvent; the mixed solvent is an aqueous solution of methanol.

[0046] The polyvinyl alcohol has an average degree of polymerization of 1700 and a degree of alcoholysis of 99%.

[0047] The organic acid is an aqueous solution of citric acid.

[0048] The citric acid aqueous solution has a citric acid concentration of 20 wt%.

[0049] The methanol concentration in the aqueous solution is 0.1 wt%.

[0050] A method for preparing heat-resistant aging polyvinyl butyral resin includes the following steps: adding polyvinyl alcohol to a mixed solvent, mixing evenly at 85±1℃, filtering, adding hydrochloric acid and organic acid and mixing evenly, cooling to 8±1℃, adding butyral dropwise, keeping warm for 30 min, raising the temperature to 60±1℃, keeping warm for 3 h, and obtaining a reaction solution of granular resin; adding sodium hydroxide solution to the reaction solution to make the pH of the reaction solution = 10, and then sequentially filtering, washing with deionized water, and drying to obtain the final product.

[0051] Example 2

[0052] Example 2 provides a heat-resistant aging polyvinyl butyral resin, which, by weight, comprises: 100 parts polyvinyl alcohol, 60 parts butyral, 30 parts organic acid, 3 parts hydrochloric acid, and 1200 parts mixed solvent; the mixed solvent is an aqueous solution of ethanol.

[0053] The polyvinyl alcohol has an average degree of polymerization of 1700 and a degree of alcoholysis of 99%.

[0054] The organic acid is an aqueous solution of sorbic acid.

[0055] The sorbic acid aqueous solution has a sorbic acid concentration of 20 wt%.

[0056] The ethanol in the aqueous solution has a mass concentration of 1 wt%.

[0057] A method for preparing heat-resistant aging polyvinyl butyral resin includes the following steps: adding polyvinyl alcohol to a mixed solvent, mixing evenly at 85±1℃, filtering, adding hydrochloric acid and organic acid and mixing evenly, cooling to 8±1℃, adding butyral dropwise, keeping warm for 30 min, raising the temperature to 60±1℃, keeping warm for 3 h, and obtaining a reaction solution of granular resin; adding sodium hydroxide solution to the reaction solution to make the pH of the reaction solution = 10, and then sequentially filtering, washing with deionized water, and drying to obtain the final product.

[0058] Example 3

[0059] Example 3 provides a heat-resistant aging polyvinyl butyral resin, which, by weight, comprises: 100 parts polyvinyl alcohol, 60 parts butyral, 30 parts organic acid, 3 parts hydrochloric acid, and 2000 parts mixed solvent; the mixed solvent is an aqueous solution of ethylene glycol.

[0060] The polyvinyl alcohol has an average degree of polymerization of 1700 and a degree of alcoholysis of 99%.

[0061] The organic acid is an aqueous solution of acetic acid.

[0062] The acetic acid in the aqueous acetic acid solution has a mass concentration of 20 wt%.

[0063] The aqueous solution of ethylene glycol has a mass concentration of 3 wt%.

[0064] A method for preparing heat-resistant aging polyvinyl butyral resin includes the following steps: adding polyvinyl alcohol to a mixed solvent, mixing evenly at 85±1℃, filtering, adding hydrochloric acid and organic acid and mixing evenly, cooling to 8±1℃, adding butyral dropwise, keeping warm for 30 min, raising the temperature to 60±1℃, keeping warm for 3 h, and obtaining a reaction solution of granular resin; adding sodium hydroxide solution to the reaction solution to make the pH of the reaction solution = 10, and then sequentially filtering, washing with deionized water, and drying to obtain the final product.

[0065] Example 4

[0066] Example 4 provides a heat-resistant aging polyvinyl butyral resin, which, by weight, comprises: 100 parts polyvinyl alcohol, 60 parts butyral, 30 parts organic acid, 3 parts hydrochloric acid, and 1600 parts mixed solvent; the mixed solvent is an aqueous solution of propylene glycol.

[0067] The polyvinyl alcohol has an average degree of polymerization of 1700 and a degree of alcoholysis of 99%.

[0068] The organic acid is an aqueous solution of succinic acid.

[0069] The succinic acid aqueous solution has a succinic acid concentration of 20 wt%.

[0070] The propylene glycol aqueous solution has a propylene glycol mass concentration of 5 wt%.

[0071] A method for preparing heat-resistant aging polyvinyl butyral resin includes the following steps: adding polyvinyl alcohol to a mixed solvent, mixing evenly at 85±1℃, filtering, adding hydrochloric acid and organic acid and mixing evenly, cooling to 8±1℃, adding butyral dropwise, keeping warm for 30 min, raising the temperature to 60±1℃, keeping warm for 3 h, and obtaining a reaction solution of granular resin; adding sodium hydroxide solution to the reaction solution to make the pH of the reaction solution = 10, and then sequentially filtering, washing with deionized water, and drying to obtain the final product.

[0072] Example 5

[0073] Example 5 provides a heat-resistant aging polyvinyl butyral resin, which, by weight, comprises: 100 parts polyvinyl alcohol, 60 parts butyral, 50 parts organic acid, 3 parts hydrochloric acid, and 2000 parts mixed solvent; the mixed solvent is an aqueous solution of glycerol.

[0074] The polyvinyl alcohol has an average degree of polymerization of 1700 and a degree of alcoholysis of 99%.

[0075] The organic acid is an aqueous solution of tartaric acid.

[0076] The tartaric acid aqueous solution has a tartaric acid concentration of 20 wt%.

[0077] The glycerol aqueous solution has a glycerol mass concentration of 8 wt%.

[0078] A method for preparing heat-resistant aging polyvinyl butyral resin includes the following steps: adding polyvinyl alcohol to a mixed solvent, mixing evenly at 85±1℃, filtering, adding hydrochloric acid and organic acid and mixing evenly, cooling to 8±1℃, adding butyral dropwise, keeping warm for 30 min, raising the temperature to 60±1℃, keeping warm for 3 h, and obtaining a reaction solution of granular resin; adding sodium hydroxide solution to the reaction solution to make the pH of the reaction solution = 10, and then sequentially filtering, washing with deionized water, and drying to obtain the final product.

[0079] Example 6

[0080] Example 6 provides a heat-resistant aging polyvinyl butyral resin, which, by weight, comprises: 100 parts polyvinyl alcohol, 60 parts butyral, 30 parts organic acid, 3 parts hydrochloric acid, and 1200 parts mixed solvent; the mixed solvent is an aqueous solution of acetone.

[0081] The polyvinyl alcohol has an average degree of polymerization of 1700 and a degree of alcoholysis of 99%.

[0082] The organic acid is an aqueous solution of oxalic acid.

[0083] The oxalic acid aqueous solution has a mass concentration of 20 wt%.

[0084] The acetone concentration in the aqueous solution is 10 wt%.

[0085] A method for preparing heat-resistant aging polyvinyl butyral resin includes the following steps: adding polyvinyl alcohol to a mixed solvent, mixing evenly at 85±1℃, filtering, adding hydrochloric acid and organic acid and mixing evenly, cooling to 8±1℃, adding butyral dropwise, keeping warm for 30 min, raising the temperature to 60±1℃, keeping warm for 3 h, and obtaining a reaction solution of granular resin; adding sodium hydroxide solution to the reaction solution to make the pH of the reaction solution = 10, and then sequentially filtering, washing with deionized water, and drying to obtain the final product.

[0086] Example 7

[0087] Example 7 provides a heat-resistant aging polyvinyl butyral resin, which, by weight, comprises: 100 parts polyvinyl alcohol, 60 parts butyral, 30 parts organic acid, 3 parts hydrochloric acid, and 1200 parts mixed solvent; the mixed solvent is an aqueous solution of cyclohexanone.

[0088] The polyvinyl alcohol has an average degree of polymerization of 1700 and a degree of alcoholysis of 99%.

[0089] The organic acid is an aqueous solution of malic acid.

[0090] The malic acid aqueous solution has a malic acid concentration of 20 wt%.

[0091] The aqueous solution of cyclohexanone has a mass concentration of 1 wt%.

[0092] A method for preparing heat-resistant aging polyvinyl butyral resin includes the following steps: adding polyvinyl alcohol to a mixed solvent, mixing evenly at 85±1℃, filtering, adding hydrochloric acid and organic acid and mixing evenly, cooling to 8±1℃, adding butyral dropwise, keeping warm for 30 min, raising the temperature to 60±1℃, keeping warm for 3 h, and obtaining a reaction solution of granular resin; adding sodium hydroxide solution to the reaction solution to make the pH of the reaction solution = 10, and then sequentially filtering, washing with deionized water, and drying to obtain the final product.

[0093] Comparative Example 1

[0094] Comparative Example 1 provides a heat-resistant aging polyvinyl butyral resin, which, by weight, comprises: 100 parts polyvinyl alcohol, 60 parts butyral, 30 parts hydrochloric acid aqueous solution, 3 parts hydrochloric acid, and 1200 parts mixed solvent; wherein the mixed solvent is an aqueous solution of ethanol.

[0095] The polyvinyl alcohol has an average degree of polymerization of 1700 and a degree of alcoholysis of 99%.

[0096] The hydrochloric acid in the aqueous solution has a mass concentration of 20 wt%.

[0097] The ethanol in the aqueous solution has a mass concentration of 1 wt%.

[0098] A method for preparing heat-resistant aging polyvinyl butyral resin includes the following steps: adding polyvinyl alcohol to a mixed solvent, mixing evenly at 85±1℃, filtering, adding hydrochloric acid and organic acid and mixing evenly, cooling to 8±1℃, adding butyral dropwise, keeping warm for 30 min, raising the temperature to 60±1℃, keeping warm for 3 h, and obtaining a reaction solution of granular resin; adding sodium hydroxide solution to the reaction solution to make the pH of the reaction solution = 10, and then sequentially filtering, washing with deionized water, and drying to obtain the final product.

[0099] Comparative Example 2

[0100] Comparative Example 2 provides a heat-resistant aging polyvinyl butyral resin, which, by weight, comprises: 100 parts polyvinyl alcohol, 60 parts butyral, 30 parts hydrochloric acid aqueous solution, 3 parts hydrochloric acid, and 1200 parts mixed solvent; wherein the mixed solvent is an aqueous solution of ethylene glycol.

[0101] The polyvinyl alcohol has an average degree of polymerization of 1700 and a degree of alcoholysis of 99%.

[0102] The hydrochloric acid in the aqueous solution has a mass concentration of 20 wt%.

[0103] The aqueous solution of ethylene glycol has a mass concentration of 3 wt%.

[0104] A method for preparing heat-resistant aging polyvinyl butyral resin includes the following steps: adding polyvinyl alcohol to a mixed solvent, mixing evenly at 85±1℃, filtering, adding hydrochloric acid and organic acid and mixing evenly, cooling to 8±1℃, adding butyral dropwise, keeping warm for 30 min, raising the temperature to 60±1℃, keeping warm for 3 h, and obtaining a reaction solution of granular resin; adding sodium hydroxide solution to the reaction solution to make the pH of the reaction solution = 10, and then sequentially filtering, washing with deionized water, and drying to obtain the final product.

[0105] Comparative Example 3

[0106] Comparative Example 3 provides a heat-resistant aging polyvinyl butyral resin, which, by weight, comprises: 100 parts polyvinyl alcohol, 60 parts butyral, 30 parts organic acid, 3 parts hydrochloric acid, and 1200 parts purified water.

[0107] The polyvinyl alcohol has an average degree of polymerization of 1700 and a degree of alcoholysis of 99%.

[0108] The organic acid is an aqueous solution of sorbic acid.

[0109] The sorbic acid aqueous solution has a sorbic acid concentration of 20 wt%.

[0110] A method for preparing heat-resistant aging polyvinyl butyral resin includes the following steps: adding polyvinyl alcohol to pure water, mixing evenly at 85±1℃, filtering, adding hydrochloric acid and organic acid and mixing evenly, cooling to 8±1℃, adding butyral dropwise, keeping warm for 30 min, raising the temperature to 60±1℃, keeping warm for 3 h, and obtaining a reaction solution of granular resin; adding sodium hydroxide solution to the reaction solution to make the pH of the reaction solution = 10, and then sequentially filtering, washing with deionized water, and drying to obtain the final product.

[0111] Performance testing:

[0112] 1. Acetal rate: The polyvinyl butyral resin provided in the example was tested for acetal rate. The specific test method is as follows: (1) Accurately weigh 0.4g of sample into a 250mL conical flask, add 20mL of anhydrous ethanol to dissolve the sample, and after complete dissolution, add 10mL of hydroxylamine hydrochloride solution with a concentration of 1mol / L; (2) After the sample is mixed evenly, install a spherical condenser on the conical flask, heat in a 95℃ water bath, and reflux for 2.5 hours; (3) After sufficient cooling (generally about 1 hour), first add 50mL of distilled water to rinse the condenser, and add the washing liquid into the conical flask. Take out the conical flask and cool it to room temperature. (4) Add 5 drops of bromophenol blue indicator, and titrate with 0.1mol / L sodium hydroxide solution until the solution color changes from yellow to yellow-green to green to disappear and turn blue. This is the titration endpoint, and the titration amount is V. (5) Perform a blank test, and the titration amount is V0. Calculate the acetal rate according to the following formula: Wherein: B-percentage of butyraldehyde, %; m-mass of sample, g; P-purity of sample, %; V-volume of sodium hydroxide solution used in sample test, mL; V0-volume of sodium hydroxide solution used in blank test, mL; N-molar concentration of sodium hydroxide solution, mol / L. Two parallel tests were performed, and the arithmetic mean was taken as the test result. The difference between the two values ​​of the parallel test results should not be greater than 0.3%. The results are shown in Table 1.

[0113] 2. Butyraldehyde utilization rate: Weigh the polyvinyl butyral resin provided in the example and calculate the butyraldehyde utilization rate as 72*(m-m0) / (54*m1), where m is the mass of polyvinyl butyral, m0 is the mass of polyvinyl alcohol, and m1 is the mass of butyraldehyde. The results are shown in Table 1.

[0114] 3. Transmittance of resin film: The polyvinyl butyral resin provided in the example was used to prepare a film, and the transmittance was tested. The specific method is as follows: (1) Take two pieces with a thickness of 2 mm and a size of 100×100 mm. 2The glass was rinsed with distilled water and dried, then wiped clean with alcohol; 7.5g of the resin to be tested was weighed; the pure resin powder was poured into the tool containing the glass, and another piece of glass was placed on top, and the glass was placed in a vulcanizing machine with a set temperature of 180℃. The set temperature was referenced from the vulcanizing machine correction results. The glass was preheated for 15-20 minutes, and the special tool was removed and pressed for 30 minutes. The surface of the assembled glass was cleaned to ensure that the film thickness after assembly was 0.6-0.7mm. (2) The impurities after assembly were visually inspected. After observing that there were no impurities, the transmittance of the assembled glass was tested with a haze meter. The results are shown in Table 1.

[0115] 4. YI (yellow index) value of resin film after 180℃ and 2h: The polyvinyl butyral resin provided in the example was prepared into a film, and the YI value after high temperature was tested. The specific method is as follows: (1) Take two pieces with a thickness of 2mm and a size of 100×100mm. 2 The glass was rinsed with distilled water and dried, then wiped clean with alcohol; 7.5g of the resin to be tested was weighed; the pure resin powder was poured into the tool containing the glass, and another piece of glass was placed on top, and the tool was placed in an aging chamber with a set temperature of 180℃. The temperature was set and heated for 2 hours. The surface of the assembled glass was cleaned to ensure that the film thickness after assembly was 0.6~0.7mm. (2) The impurities after assembly were visually inspected. After observing that there were no impurities, the YI value of the assembled glass was tested with a haze meter. The results are shown in Table 1.

[0116] Table 1 Performance Characterization Tests

[0117]

[0118] As can be seen from Table 1, by adding mixed solvents and organic acids, the amount of hydrochloric acid used is reduced, which is beneficial to improving the heat aging resistance of the polyvinyl butyral resin of the present invention. Moreover, the acetal rate and butyral utilization rate of the obtained resin are not lower than those of hydrochloric acid catalysis. When used as an intermediate film or encapsulation material, it has high light transmittance, sun resistance, weather resistance and heat resistance.

Claims

1. A heat-resistant and aging-resistant polyvinyl alcohol acetal resin, characterized in that, By weight, the raw materials include: 100 parts polyvinyl alcohol, 60 parts butyraldehyde, 10 parts organic acid, 3 parts hydrochloric acid, and 500 parts mixed solvent; the mixed solvent is an aqueous solution of methanol. The polyvinyl alcohol has an average degree of polymerization of 1700 and a degree of alcoholysis of 99%. The organic acid is an aqueous solution of citric acid; The citric acid aqueous solution has a citric acid concentration of 20 wt%. The methanol concentration in the aqueous solution is 0.1 wt%.

2. A method for preparing the heat-resistant aging-resistant polyvinyl acetal resin according to claim 1, characterized in that, Includes the following steps: Polyvinyl alcohol is added to a mixed solvent and mixed evenly. Then hydrochloric acid and organic acid are added and mixed evenly. Finally, aldehyde is added and reacted to obtain the product.

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