Weatherable pvc resin, its preparation method and use

Abstract

The application discloses a kind of weather-resistant PVB resin and its preparation method and application.A kind of preparation method of weather-resistant PVB resin includes the following steps: polyvinyl alcohol aqueous solution is cooled to 4-12 ℃, then emulsifier, acid catalyst is added, stirring, aldehyde is added to perform acetalization reaction, after heat preservation 0.5-1.5 h, temperature is raised to 60-75 ℃, then boric acid salt is added, and it is maintained at 60-75 ℃ for 1-2 h;Add base to perform acid-base neutralization reaction, wash with water after acid-base neutralization reaction, then adjust pH value to 11-12 by adding base again, wash with water again, centrifugal to obtain final product.The PVB resin preparation method of the application, by adding boric acid salt additive, improves the oxidation corrosion resistance and heat resistance of the resin, thereby further improving weather resistance.

Description

Technical Field

[0001] This invention relates to the field of PVB resin preparation methods, specifically to a weather-resistant PVB resin, its preparation method, and its applications. Background Technology

[0002] Polyvinyl butyral (PVB) is a high-molecular-weight resin material widely used in high-rise building curtain wall glass, ceramic products, and more. High-quality PVB is currently widely used in the automotive industry. Because automotive windshields require different levels of safety than ordinary glass, they have much higher requirements for toughness, hardness, refractive index, and light transmittance. The molecular structure of PVB determines that it possesses superior physical and chemical properties compared to other polymers, namely high viscosity, good film-forming properties, high tensile strength, and good impact resistance and elasticity. These characteristics make it suitable for use in low-temperature environments, strong light environments, high-temperature environments, and under strong impact. PVB polymer material is precisely the safety film used for automotive windshields and is an essential and crucial step in the automotive manufacturing process.

[0003] Currently, PVB films are mainly produced by hot-melt casting and extrusion of PVB resin. PVB resin is prepared from polyvinyl alcohol (PVA) through an acetal reaction. In existing technologies, good weather resistance PVB resin is typically obtained by changing the additives added during the PVA acetal reaction or by altering the reaction conditions. While such adjustments are theoretically feasible, changing the reaction conditions poses significant risks. For example, if the temperature is too low or too high, the hydroxyl groups on the PVA molecular chain first react with n-butyraldehyde to form a hemiacetal. Then, under acid catalysis, the hydroxyl groups on the hemiacetal protonate to form water. This water can only dehydrate and cyclize to form a six-membered ring acetal at a certain temperature. If the reaction temperature is too low, the hemiacetal is difficult to cyclize and is unstable, decomposing into PVA and n-butyraldehyde. If the reaction temperature is too high, the already formed six-membered ring acetal can also hydrolyze and open under acidic conditions, decomposing into PVA and n-butyraldehyde, leading to a continuous increase in the acetalization rate during the reaction. In summary, existing PVB resins have the problem of substandard weather resistance. Summary of the Invention

[0004] To overcome the problem of substandard weather resistance of existing PVB resins, one objective of this invention is to provide a method for preparing a weather-resistant PVB resin; a second objective of this invention is to provide a weather-resistant PVB resin obtained by this method; and a third objective of this invention is to provide applications of this weather-resistant PVB resin.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] The first aspect of this invention provides a method for preparing weather-resistant PVB resin, comprising the following steps:

[0007] After cooling the polyvinyl alcohol aqueous solution to 4-12℃, emulsifier and acid catalyst are added, stirred, and aldehydes are added to carry out acetalization reaction. After keeping it at this temperature for 0.5-1.5h, the temperature is raised to 60-75℃ and then borates are added. The temperature is maintained at 60-75℃ for 1-2h. An acid-base neutralization reaction is carried out by adding alkali. After the acid-base neutralization reaction, the product is washed with water, and then alkali is added again to adjust the pH value to 11-12. The product is washed with water again and centrifuged to obtain the final product.

[0008] Preferably, the weather-resistant PVB resin is prepared by means of the following raw materials in parts by weight: 100 parts of polyvinyl alcohol, 0.5-0.65 parts of emulsifier, 40-70 parts of aldehyde, and 4-7 parts of borate.

[0009] Preferably, the mass concentration of the polyvinyl alcohol aqueous solution is ≤10%.

[0010] Preferably, the acid catalyst is at least one of hydrochloric acid and sulfuric acid; the amount of acid catalyst added satisfies that the pH of the solution after addition is ≤2.

[0011] Preferably, after the polyvinyl alcohol aqueous solution is cooled to 6-10°C, an emulsifier and an acid catalyst are added.

[0012] Preferably, in the preparation method of the weather-resistant PVB resin, aldehydes are added to carry out an acetalization reaction, and after holding at a temperature for 0.8-1.2h, the temperature is raised to 65-70℃ and then borate is added, and the temperature is maintained at 65-70℃ for 1-2h.

[0013] Preferably, the aldehydes include at least one of formaldehyde, acetaldehyde, n-butyraldehyde, lauraldehyde, tridecanal, myristaldehyde, methylhexylacetaldehyde, methyl octylacetaldehyde, methyl nonylacetaldehyde, trimethylhexanal, tetramethylhexanal, trans-2-hexenal, 2-nonenal, trans-4-decenal, undecenal, and nonadienal.

[0014] Preferably, the aldehydes are added in two steps: after adding the emulsifier and acid catalyst, a portion of the aldehydes are added, and the remaining aldehydes are added simultaneously with the addition of the borate.

[0015] More preferably, the aldehydes are added in two steps, with the carbon chain of the later-added aldehyde being shorter than that of the earlier-added aldehyde. In some preferred embodiments of the present invention, the earlier-added aldehyde is butyraldehyde, and the later-added aldehyde is an aldehyde with a shorter carbon chain than butyraldehyde, for example, acetaldehyde. The polyvinyl butyral resin of the present invention is prepared by a two-step precipitation method. After a certain reaction time, an appropriate amount of acetaldehyde and boric acid additive are added to form a mixed polyvinyl butyral product. The carbon chain of acetaldehyde is shorter than that of butyraldehyde. The longer the carbon chain of the aldehyde, the higher the toughness and elasticity of the resin, but the poorer the heat resistance. Adding a small amount of acetaldehyde after a certain reaction time helps to improve the heat resistance of the mixed resin. The borate additive will form a complex borate film with the dissolved oxygen therein, which can alleviate surface corrosion and improve the resistance to oxidation corrosion.

[0016] Preferably, the viscosity of the polyvinyl alcohol at 20°C is 20-30 cp; more preferably, the viscosity of the polyvinyl alcohol at 20°C is 22-24 cp.

[0017] Preferably, the degree of polymerization of the polyvinyl alcohol is 1000-3000; when the degree of polymerization of polyvinyl alcohol is less than 1000, the viscosity of the obtained polyvinyl alcohol acetal product is low, and the strength of the PVB film is insufficient; when the degree of polymerization of polyvinyl alcohol exceeds 3000, the viscosity in water is high, making it difficult for the acetalization reaction to be complete.

[0018] Preferably, the emulsifier includes at least one of rosin acid, resin acid, sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, sodium alkyl sulfonate, and sodium dibutylnaphthalene sulfonate; in some specific embodiments of the present invention, the emulsifier is sodium dodecylbenzene sulfonate.

[0019] Preferably, the borate includes at least one of metaborate, orthoborate, and polyborate; more preferably, the borate is a nitrogen-containing borate ester, wherein the coordination bond formed by nitrogen and boron is more conducive to the stability of the structure.

[0020] A second aspect of the present invention provides a weather-resistant PVB resin, which is prepared by the above-described method for preparing weather-resistant PVB resin.

[0021] Preferably, the hydroxyl content of the weather-resistant PVB resin is 16-22 wt%.

[0022] The weather-resistant PVB resin of the present invention may also contain additives such as flame retardants, antistatic agents, surfactants, fluorescent whitening agents, and oxidants as needed. These additives may be used alone or in combination of two or more.

[0023] A third aspect of the present invention provides the application of this weather-resistant PVB resin in the preparation of interlayer films in laminated glass.

[0024] The beneficial effects of this invention are:

[0025] The PVB resin preparation method of the present invention improves the resin's resistance to oxidation and corrosion, as well as its heat resistance, by adding borate additives, thereby further enhancing its weather resistance.

[0026] The PVB resin prepared by this invention has better heat resistance than conventional resins, and also shows good improvement in flexibility and adhesion. It can be used for the preparation of interlayer films in laminated glass, and has significant economic and social benefits. Attached Figure Description

[0027] Figure 1 The PVB resin prepared in Example 1;

[0028] Figure 2 The PVB resin prepared in Example 2;

[0029] Figure 3 The PVB resin prepared in Comparative Example 1;

[0030] Figure 4 The PVB resin prepared for Comparative Example 2. Detailed Implementation

[0031] The present invention will be further described in detail below through specific embodiments. Unless otherwise specified, the raw materials, reagents, or apparatus used in the embodiments and comparative examples are all available from conventional commercial sources or can be obtained by existing technical methods. Unless otherwise specified, the test or experimental methods are conventional methods in the art.

[0032] Example 1

[0033] The method for preparing the weather-resistant PVB resin in this embodiment includes the following steps:

[0034] 1) Preparation of polyvinyl alcohol aqueous solution: Add 100 parts by weight of polyvinyl alcohol (PVA) to an appropriate amount of deionized water to prepare a polyvinyl alcohol aqueous solution with a mass fraction of less than 10%, and heat to dissolve.

[0035] 2) Cooling condensation: After slowly cooling the dissolved PVA solution to 8°C, while maintaining the stirring rate, add 0.6 parts by weight of sodium dodecylbenzenesulfonate (DBS) as an emulsifier and stir it thoroughly. Then add 13 parts by weight of hydrochloric acid as a catalyst to maintain the solution acidity at pH ≤ 2. After stirring thoroughly, slowly add 46 parts by weight of n-butyraldehyde and slightly increase the stirring rate to prevent solid agglomeration until the acetalization reaction is completed and the solution becomes heterogeneous. After keeping it at a low temperature for 1 hour, raise the temperature at a uniform rate to 67.5°C and add 11.5 parts by weight of acetaldehyde and 6 parts by weight of a borate ester mixture. Keep it at this temperature for 1.5 hours.

[0036] 3) Neutralization: After the incubation at 67.5℃ is completed, add an appropriate amount of liquid alkali to adjust the pH of the solution to between 3.8 and 4.1, neutralize the acidity and slow down the acetal reaction, and incubate for 0.5h.

[0037] 4) Post-processing: After the neutralization with alkali is completed, the product is washed with cold water several times, an appropriate amount of liquid alkali is added to terminate the reaction, the pH is adjusted to between 11 and 12, and then washed with hot water several times. The product is obtained by centrifugation, air drying, etc.

[0038] Example 2

[0039] The method for preparing the weather-resistant PVB resin in this embodiment includes the following steps:

[0040] 1) Preparation of polyvinyl alcohol aqueous solution: Add 100 parts by weight of polyvinyl alcohol to an appropriate amount of deionized water to prepare a polyvinyl alcohol aqueous solution with a mass fraction of less than 10%, and heat to dissolve.

[0041] 2) Cooling condensation: After slowly cooling the dissolved PVA solution to 8°C, while maintaining the stirring rate, add 0.6 parts by weight of sodium dodecylbenzenesulfonate (DBS) emulsifier and stir it thoroughly. Then add 13 parts by weight of hydrochloric acid catalyst to maintain the solution acidity at pH ≤ 2. After stirring evenly, slowly add 57.5 parts by weight of n-butyraldehyde and slightly increase the stirring rate to prevent solid agglomeration until the acetalization reaction is completed and the solution becomes heterogeneous. After keeping it at a low temperature for 1 hour, raise the temperature at a uniform rate to 67.5°C and add 6 parts by weight of borate ester mixture. Keep it at this temperature for 1.5 hours.

[0042] 3) Neutralization: After the incubation at 67.5℃ is completed, add an appropriate amount of liquid alkali to adjust the pH of the solution to between 3.8 and 4.1, neutralize the acidity and slow down the acetal reaction, and incubate for 0.5h.

[0043] 4) Post-processing: After the neutralization with alkali is completed, the product is washed with cold water several times, an appropriate amount of liquid alkali is added to terminate the reaction, the pH is adjusted to between 11 and 12, and then washed with hot water several times. The product is obtained by centrifugation, air drying, etc.

[0044] Comparative Example 1

[0045] The preparation method of the weather-resistant PVB resin in this comparative example includes the following steps:

[0046] 1) Preparation of polyvinyl alcohol aqueous solution: Add 100 parts by weight of polyvinyl alcohol to an appropriate amount of deionized water to prepare a polyvinyl alcohol aqueous solution with a mass fraction of less than 10%, and heat to dissolve.

[0047] 2) Cooling condensation: After slowly cooling the dissolved PVA solution to 8°C, while maintaining the stirring rate, add 0.6 parts by weight of sodium dodecylbenzenesulfonate (DBS) as an emulsifier and stir it thoroughly. Then add 13 parts by weight of hydrochloric acid as a catalyst to maintain the solution acidity at pH ≤ 2. After stirring thoroughly, slowly add 46 parts by weight of n-butyraldehyde and slightly increase the stirring rate to prevent solid agglomeration until the acetalization reaction is completed and the solution becomes heterogeneous. After keeping it at a low temperature for 1 hour, raise the temperature at a uniform rate to 67.5°C and add 11.5 parts by weight of acetaldehyde. Keep it at this temperature for 1.5 hours.

[0048] 3) Neutralization: After the incubation at 67.5℃ is completed, add an appropriate amount of liquid alkali to adjust the pH of the solution to between 3.8 and 4.1, neutralize the acidity and slow down the acetal reaction, and incubate for 0.5h.

[0049] 4) Post-processing: After the neutralization with alkali is completed, the product is washed with cold water several times, an appropriate amount of liquid alkali is added to terminate the reaction, the pH is adjusted to between 11 and 12, and then washed with hot water several times. The product is obtained by centrifugation, air drying, etc.

[0050] Comparative Example 2

[0051] The preparation method of the weather-resistant PVB resin in this comparative example includes the following steps:

[0052] 1) Preparation of polyvinyl alcohol aqueous solution: Add 100 parts by weight of polyvinyl alcohol to an appropriate amount of deionized water to prepare a polyvinyl alcohol aqueous solution with a mass fraction of less than 10%, and heat to dissolve.

[0053] 2) Cooling condensation: After slowly cooling the dissolved PVA solution to 8°C, while maintaining the stirring rate, add 0.6 parts by weight of sodium dodecylbenzenesulfonate (DBS) emulsifier and stir it thoroughly. Then add 13 parts by weight of hydrochloric acid catalyst to maintain the solution acidity at pH ≤ 2. After stirring evenly, slowly add 57.5 parts by weight of n-butyraldehyde and slightly increase the stirring rate to prevent solid agglomeration until the acetalization reaction is completed and the solution becomes heterogeneous. Then keep it at low temperature for 1 hour and then raise the temperature to 67.5°C at a uniform rate. Keep it at this temperature for 1.5 hours.

[0054] 3) Neutralization: After the incubation at 67.5℃ is completed, add an appropriate amount of liquid alkali to adjust the pH of the solution to between 3.8 and 4.1, neutralize the acidity and slow down the acetal reaction, and incubate for 0.5h.

[0055] 4) Post-processing: After the neutralization with alkali is completed, the product is washed with cold water several times, an appropriate amount of liquid alkali is added to terminate the reaction, the pH is adjusted to between 11 and 12, and then washed with hot water several times. The product is obtained by centrifugation, air drying, etc.

[0056] The PVB resin prepared above was subjected to the following performance tests:

[0057] (1) Determination of hydroxyl content:

[0058] 1. Test reagents: pyridine (AR), acetic anhydride (AR), 1,2-dichloroethane (AR), phenolphthalein indicator, sodium hydroxide standard solution (0.5 mol / L).

[0059] 2. Test Method: Accurately weigh 1 g (0.1 mg accurate) of polyvinyl acetal sample into a 250 mL ground glass conical flask. Prepare a mixture of 90 mL pyridine and 10 mL acetic anhydride in a fume hood. Accurately add 10 mL of this mixture to the sample. Attach a condenser to the conical flask and reflux at 95 °C for 3 hours until the sample is completely dissolved. Cool the mixture to room temperature, then add 25 mL of 1,2-dichloroethane from the top of the condenser. Remove the condenser, stopper the flask, and gently shake. Add 5 mL of distilled water to wash the stopper and flask walls, gently shake, and let stand for 1 hour. Pipette 25 mL of distilled water along the walls of the conical flask, add 2 mL of phenolphthalein indicator, and titrate with 0.5 mol / L sodium hydroxide standard solution. Analytical Results: The reaction product acetic acid can be detected with 0.5 mol / L sodium hydroxide standard solution. Let Vs represent the volume of NaOH neutralizing acetic acid, and E represent the mass of the neutralized sample. Let Vb represent the volume of NaOH standard solution consumed by the blank sample, that is, the volume in the blank sample in which acetic anhydride is completely converted into acetic acid. 1 mol of acetic acid corresponds to 1 mol of polyvinyl alcohol (44 g).

[0060] Hydroxyl content is calculated using the following formula

[0061]

[0062] In the formula:

[0063] X – Hydroxyl content, %;

[0064] Vb – Volume of sodium hydroxide standard solution consumed in titration of blank sample, mL;

[0065] Vs – Volume of sodium hydroxide standard solution consumed in titrating the sample, in mL;

[0066] C – Actual concentration of sodium hydroxide standard solution, mol / L;

[0067] E – Sample mass, g;

[0068] H – Volatile content of the sample, resin volatile content determination result, %.

[0069] Two parallel tests should be performed, and the arithmetic mean of the two results should be taken as the test result. The significant values ​​should be rounded to two decimal places according to the provisions of GB / T1250 and GB / T8170. Permissible error: The difference between the two values ​​of the parallel test results shall not exceed 0.3%.

[0070] (2) Determination of volatile resins:

[0071] 1. Experimental apparatus: electronic analytical balance, desiccator, moisture analyzer.

[0072] 2. Test Method: Before using the instrument, connect the power supply. Set the temperature to 90℃ and the detection time to 5 minutes. Place the iron pan containing the powder into the instrument and zero it. Weigh 5-8g (±0.1g) of the sample using a foil paper pan, place it into the instrument, and press the "start" switch to begin the test. The instrument will sound an alarm after the test is complete. Press the "stop" button to read the data. The read data is the moisture content to be measured. Two parallel tests should be performed, and the arithmetic mean of the two results should be taken as the test result. The significant value should be rounded to two decimal places according to the provisions of GB / T1250 and GB / T8170. Allowable error: The difference between the two values ​​of the parallel test results should not exceed 0.3%.

[0073] (3) Determination of resin melt index content:

[0074] 1. Test reagent: plasticizer.

[0075] 2. Test Method: Before using the instrument, level it. Connect the power supply, set the temperature to 118℃, and heat. Once the temperature displayed on the digital thermometer reaches 118℃, maintain the temperature for 20-30 minutes. Set the parameters: sampling mode is "time-controlled," sampling time is 300s, and the load is 21.6kg. Weigh 1.250g of plasticizer and 3.750g of PVB resin samples separately using an electronic balance. Stir with a glass rod until the mixture is homogeneous. Remove the guide sleeve and plunger, and quickly add the mixture into the barrel using a funnel. Replace the plunger and guide sleeve, and press firmly. The entire process should be completed within one minute. Press the test button to reset the time display to zero. Connect the photoelectric sensor and displacement gauge. Move the handwheel to raise or lower the rack until the swing arm engages the center of the base weight. Then rotate the handwheel to lower the rack. When the piston reaches the lower mark, it contacts the photoelectric sensor, the instrument cuts the material once, and an audible alarm sounds, starting the timer. After applying the required load and preheating for four minutes, remove the swing arm, press the reset button first, then the test button, and start the timing test again. Each time the time display reaches the set value, cut the material once and restart the timing. Take two consecutive sections of material, cool them, and weigh them. The resulting weight is the melt flow index value.

[0076] After cutting the sample strip, turn the handwheel to disengage the weight holder from the plunger, pull out the plunger guide sleeve, pull out the furnace body pull plate, and gently press the die out of the material cylinder with the cleaning rod. Immediately clean the inner hole with the die drill, and then wipe the outer surface clean with cotton gauze. Wrap the cotton gauze around the head of the cleaning rod and insert it into the material cylinder to wipe until the cylinder is clean. Push the furnace body pull plate in, install the die, plunger, and guide sleeve, and preheat for 4-5 minutes before the next test. Retain two decimal places for the values.

[0077] (4) Resin viscosity test:

[0078] 1. Test reagents: n-Butanol: AR.

[0079] 2. Test methods:

[0080] Dissolution: Place the sample (>8g) in a moisture analyzer (90±1℃) and bake for 5 minutes, then remove and cool in a desiccator; then weigh 7±0.01g of the sample and 133g±0.1g of n-butanol solvent. Add approximately half of the n-butanol to a clean, dry 250mL three-necked flask (with stirring). While stirring, slowly add 7g of the sample, then add the remaining reagent to the three-necked flask. Open the constant temperature water bath and maintain the temperature at (50±2℃) to dissolve the sample until it is completely dissolved.

[0081] Calculation of total solvent weight:

[0082]

[0083] In the formula:

[0084] R – Volatile content, resin volatile content determination result, %;

[0085] T – Total weight of solvent, in grams.

[0086] Viscosity testing steps:

[0087] Use the level indicator to ensure the instrument is level. Install the rotor and cup: Place rotor #3 into cup #3, and tighten the screw end of rotor #3 counterclockwise to the rotor connection port of the instrument; then adjust the height of the viscometer using the screws on the viscometer holder, ensuring the liquid level mark on the rotor is in the cup and the rotor is not in contact with the bottom of the cup; slightly move the cup so that the rotor is in the center of the cup.

[0088] Sample preparation: Use a thermometer to check that the sample temperature is 20℃. Then pour the resin sample into cup No. 3 up to the liquid level mark on the rotor, avoiding the mixing of air bubbles and impurities.

[0089] Sample testing: First, open the indicator needle by moving the pointer clamp in the opposite direction of the arrow. Then, turn the instrument power switch to "ON". After the rotor starts rotating, the sample solution will remain balanced at a certain position. When the pointer remains unchanged at a certain scale for about 10 seconds, you can read the reading the pointer is pointing to in range NO.3. After the test, turn the power switch to "OFF", close the indicator needle by moving the pointer clamp in the direction of the arrow, and unscrew the rotor in the clockwise direction. Then, pour the test sample back into the original sample container and wash the rotor and cup with solvent.

[0090] Result calculation:

[0091] Viscosity value (CP / 20℃) = Reading (P) × 100

[0092] (5) Resin heat resistance test:

[0093] 1. Test apparatus: Oven.

[0094] 2. Test method: Weigh 5g of sample and place it in a container. Set the oven to 180℃, put the sample in the oven, and bake at high temperature for 30 minutes. Then take it out and observe the degree of yellowing of the sample.

[0095] The test results are shown in Table 1 below.

[0096] Table 1 Performance Test Results

[0097] Test item Example 1 Example 2 Comparative Example 1 Comparative Example 2 Hydroxyl content 18.8％ 18.1％ 18.0％ 18.7％ Volatile matter 0.1％ 0.1％ 0.1％ 0.1％ Melt index 6.6 7.2 6.5 7.0 Viscosity 230 230 210 210 Heat resistance Normal Slightly yellowed Yellowed Yellowed

[0098] Images of the PVB resins finally prepared in Examples 1-2 and Comparative Examples 1-2 are attached. Figures 1-4 As shown in the above test results, compared with the control group without borate additives, the PVB resin with borate additives has better resistance to oxidation and corrosion. When the addition ratio is the same, using butyraldehyde and acetaldehyde as acetal reaction reagents results in a lower melt index and higher heat resistance.

[0099] The above embodiments are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a weather-resistant PVB resin, characterized in that, Includes the following steps: After cooling the polyvinyl alcohol aqueous solution to 4-12℃, emulsifier and acid catalyst are added, stirred, and aldehydes are added to carry out acetalization reaction. After keeping it at this temperature for 0.5-1.5h, the temperature is raised to 60-75℃ and then borates are added. The temperature is maintained at 60-75℃ for 1-2h. An acid-base neutralization reaction is carried out by adding alkali. After the acid-base neutralization reaction, the product is washed with water, and then the pH is adjusted to 11-12 by adding alkali again. The product is washed with water again and centrifuged to obtain the final product. The aldehydes are added in two steps: after adding the emulsifier and acid catalyst, some aldehydes are added; and the remaining aldehydes are added at the same time as the borates are added. The carbon chain of the aldehydes added later is shorter than that of the aldehydes added earlier. The weather-resistant PVB resin comprises the following raw materials in parts by weight: 100 parts polyvinyl alcohol, 0.5-0.65 parts emulsifier, 40-70 parts aldehyde, and 4-7 parts borate.

2. The method for preparing the weather-resistant PVB resin according to claim 1, characterized in that, The aldehydes include at least one of formaldehyde, acetaldehyde, n-butyraldehyde, lauraldehyde, tridecanal, myristaldehyde, methylhexylacetaldehyde, methyl octylacetaldehyde, methyl nonylacetaldehyde, trimethylhexanal, tetramethylhexanal, trans-2-hexenal, 2-nonenal, trans-4-decenal, undecenal, and nonadienal.

3. The method for preparing weather-resistant PVB resin according to claim 1, characterized in that, The viscosity of the polyvinyl alcohol at 20°C is 20-30 cp.

4. The method for preparing the weather-resistant PVB resin according to claim 3, characterized in that, The degree of polymerization of the polyvinyl alcohol is 1000-3000.

5. The method for preparing weather-resistant PVB resin according to claim 1, characterized in that, The borates include at least one of metaborates, orthoborates, and polyborates.

6. A weather-resistant PVB resin, characterized in that, It is prepared by the method for preparing weather-resistant PVB resin according to any one of claims 1 to 5.

7. The application of the weather-resistant PVB resin according to claim 6 in the preparation of interlayer film in laminated glass.

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