CN103193905B - Low-viscosity polyvinyl butyral resin, preparation method and application thereof - Google Patents

Abstract

The present invention relates to a method for preparing a low-viscosity polyvinyl butyral resin. The method adopts a two-step precipitation method, adjusts the temperature of a polyvinyl alcohol aqueous solution to 0-5°C, then adds an acid catalyst and n-butyraldehyde, performs an acetalization reaction, and obtains a low-viscosity polyvinyl butyral resin. The present invention obtains a PVB resin with a higher acetalization degree through the control of the formula and process, improves the bonding force, and the butyraldehyde group of the PVB resin can reach more than 80%, and can be used in inks, coatings and adhesives.

Description

A kind of low-viscosity polyvinyl butyral resin, preparation method and application thereof

technical field

The present invention relates to a kind of polyvinyl butyral PVB resin, preparation method and application thereof, in particular to a kind of preparation method of low viscosity polyvinyl butyral PVB resin, which is mainly used in the production of coatings, inks and adhesives Among them, it belongs to the field of polymer chemical industry.

Background technique

Polyvinyl butyral (PVB) is prepared by acetalization reaction of polyvinyl alcohol (PVA) and butyraldehyde (BA) under acid catalysis. It is a non-toxic, odorless and non-corrosive resin . Because the PVB molecule contains a long branched chain, it has good flexibility, low glass transition temperature, high tensile strength and impact strength; PVB has excellent transparency, good solubility, excellent insulation performance, very good Light resistance, water resistance, heat resistance, cold resistance and film-forming properties; the functional groups it contains can carry out various reactions such as saponification of acetyl groups, esterification and sulfonation of hydroxyl groups; it is compatible with glass, metal (especially aluminum) and other materials It has high adhesive force and has multiple functions such as safety, heat preservation, noise control and UV protection. At the same time, polyvinyl butyral PVB resin is white or slightly yellow powder or fine particles, which has excellent light resistance, heat resistance, cold resistance, oil resistance, abrasion resistance, film formation, impact resistance and corrosion resistance. Coatings and adhesives have a wide range of applications.

The ink resin is used as the carrier of the pigment in the ink and is the core material of the ink. Its quality will directly affect the performance of the ink. With the continuous development of ink technology, people have put forward higher requirements for PVB resin materials used in ink, such as no decolorization of substrates, no discoloration, and bright packaging appearance. To meet the above requirements, PVB resin must have strong adhesion (the size of the adhesion is determined by the content of butyraldehyde), and the coating film should be bright and not easy to change color. However, PVB resins in the prior art are far from satisfying the above characteristics.

In the traditional low-viscosity polyvinyl butyral PVB resin preparation process, due to the slow degradation of PVA, the entire preparation process cycle is long and the production efficiency is low. This requires that in the process of preparing low-viscosity polyvinyl butyral PVB resin, through formula and process adjustment, while improving production efficiency, successfully prepare low-viscosity polyvinyl butyral resin with high stability, high transparency and high degree of acetalization Viscosity PVB resin.

Contents of the invention

Aiming at the problems existing in the above-mentioned prior art, the invention provides a kind of preparation method of low-viscosity polyvinyl butyral PVB resin, solves low-viscosity polyvinyl butyral PVB resin production efficiency is low, acetalization degree partial Low, coating film is not bright, easy to change color and other problems.

In order to achieve the above object, the present invention adopts following technical scheme:

A method for preparing low-viscosity polyvinyl butyral resin, the method adopts a two-step precipitation method, adjusts the temperature of polyvinyl alcohol aqueous solution to 0-5°C, and then adds acid catalyst and n-butyraldehyde to carry out acetalization reaction , to obtain low viscosity polyvinyl butyral resin. Low-temperature reaction (0-5°C), which solves the problems of low viscosity polyvinyl butyral PVB resin with low acetalization degree, dull coating film and easy discoloration.

Preferably, the method adopts a two-step precipitation method, adjusting the pH value of the polyvinyl alcohol aqueous solution to 9-11, adding degradation agents and accelerators, then adjusting the temperature of the polyvinyl alcohol aqueous solution to 0-5 ° C, adding acid catalysts and normal Butyraldehyde is subjected to acetalization reaction to obtain low-viscosity polyvinyl butyral resin. Adding a degradation agent degrades the polyvinyl alcohol and reduces the length of the main chain to obtain a low-viscosity polyvinyl butyral resin. The addition of the accelerator accelerates the degradation rate of PVA and improves the production efficiency of PVB resin. It takes 1 to 1.5 hours for PVA to degrade before the accelerator is added, which shows that the solution viscosity is low and the system is not viscous. After adding the accelerator, it takes 10-20 minutes for PVA to completely degrade. Adding an accelerator can promote the full degradation of polyvinyl alcohol.

Preferably, the method comprises the steps of:

(1) Dissolving polyvinyl alcohol in water to obtain an aqueous solution of polyvinyl alcohol;

(2) Adjust the pH value of the polyvinyl alcohol aqueous solution to 9-11, and add degradation agents and accelerators;

(3) adding an emulsifier to the polyvinyl alcohol aqueous solution obtained in step (2);

(4) adjusting the temperature of the polyvinyl alcohol aqueous solution obtained in step (3) to 0-5° C., and adding acid catalyst, n-butyraldehyde and antioxidant to carry out acetalization reaction;

(5) Gradually heat up to the reaction temperature and react;

(6) Dehydrating the reaction product, stabilizing it with an alkali solution, washing it with water, and drying it to obtain a white powdery polyvinyl butyral resin.

Preferably, the polyvinyl alcohol is dissolved in water at no more than 98°C, preferably the polyvinyl alcohol is dissolved in water at 90-98°C. For example, polyvinyl alcohol is dissolved in water at 91°C, 92°C, 93°C, 94°C, 95°C, 96°C or 97°C. The water is deionized water. If the temperature is too low, the dissolution rate of polyvinyl alcohol will be too slow; if the temperature is too high, such as higher than 100°C, the dissolution process of polyvinyl alcohol will be too violent and foam will easily occur.

Preferably, the concentration of the polyvinyl alcohol aqueous solution in step (1) is 7-12wt%, that is, the mass percentage of polyvinyl alcohol in the polyvinyl alcohol aqueous solution is 7-12wt%, preferably 8-11wt%, such as 7.2wt%, 7.6wt%, 8.2wt%, 8.8wt%, 9.3wt%, 9.8wt%, 10.2wt%, 10.7wt%, 11.2wt%, 11.6wt%.

Preferably, the pH value is adjusted by adding a pH regulator to the polyvinyl alcohol aqueous solution obtained in step (1).

Preferably, the emulsifier is added after adjusting the temperature of the polyvinyl alcohol aqueous solution obtained in step (2) to 30-40°C, preferably after adjusting the temperature of the polyvinyl alcohol aqueous solution obtained in step (2) to 32-38°C. For example, after adjusting the temperature of the polyvinyl alcohol aqueous solution obtained in step (2) to 31°C, 33°C, 34°C, 35°C, 36°C, 37°C or 39°C, the emulsifier is added. If the adding temperature is too high, it is easy to make the solution foam, and after adding the emulsifier, there must be sufficient time to make the solution stir evenly.

Preferably, the time for the acetalization reaction in step (4) is 1 to 2 hours, such as 1.1 hours, 1.2 hours, 1.3 hours, 1.4 hours, 1.5 hours, 1.6 hours, 1.7 hours, 1.8 hours, 1.9 hours, preferably 1.05 to 1.95 hours, more preferably 1.15 to 1.85 hours.

Preferably, the reaction temperature in step (5) is 30-40°C, such as 31°C, 32°C, 33°C, 34°C, 35°C, 36°C, 37°C, 38°C, 39°C, preferably 31.5-38.5°C , more preferably 32.5 to 37.5°C.

Preferably, the reaction time in step (5) is 2 to 3 hours, such as 2.1 hours, 2.2 hours, 2.3 hours, 2.4 hours, 2.5 hours, 2.6 hours, 2.7 hours, 2.8 hours, 2.9 hours, preferably 2.15 to 2.85 hours hours, more preferably 2.25 to 2.75 hours.

Preferably, in step (6), after centrifuging and dehydrating the reaction product, add an alkaline solution for stabilization treatment for 2-3 hours, control the pH value within 9-10, wash twice with deionized water at 50-60°C, and finally Wash with deionized water and dry to obtain powdery low-viscosity polyvinyl butyral resin.

Preferably, the acid catalyst is any one or a mixture of at least two of dilute hydrochloric acid, dilute sulfuric acid or dilute phosphoric acid. The mixture is, for example, a mixture of dilute hydrochloric acid and dilute sulfuric acid, a mixture of dilute hydrochloric acid and dilute phosphoric acid, a mixture of dilute sulfuric acid and dilute phosphoric acid, a mixture of dilute hydrochloric acid, dilute sulfuric acid and dilute phosphoric acid. The dilute hydrochloric acid refers to hydrochloric acid with a mass fraction lower than 37%, the dilute sulfuric acid refers to sulfuric acid with a concentration below 70%, and the dilute phosphoric acid refers to 9.5-10.5 g of phosphoric acid (H ₃ PO ₄ ) per 100 ml.

Preferably, the emulsifier is selected from any one of sodium lauryl sulfate, sodium dodecylsulfonate or sodium dodecylbenzenesulfonate or a mixture of at least two of them. Said mixture is, for example, a mixture of sodium dodecylbenzenesulfonate and sodium dodecylsulfonate, a mixture of sodium dodecylbenzenesulfonate and sodium dodecylsulfate, a mixture of sodium dodecylbenzenesulfonate and sodium dodecylsulfonate, A mixture of sodium dialkylsulfate, sodium dodecylbenzenesulfonate, a mixture of sodium laurylsulfonate and sodium laurylsulfate.

Preferably, the antioxidant is any one of antioxidant 1010, antioxidant 168, antioxidant DLTDP, antioxidant 1076 or antioxidant 1024 or a mixture of at least two. Said mixture is for example the mixture of antioxidant 1010 and antioxidant 168, the mixture of antioxidant DLTDP and antioxidant 1076, the mixture of antioxidant 1010, antioxidant 168 and antioxidant DLTDP, antioxidant 1076, A mixture of Antioxidant 1024 and Antioxidant 1010.

Preferably, the degradation agent is sodium hypochlorite or/and hydrogen peroxide.

Preferably, the alkaline solution is any one or a mixture of at least two of potassium hydroxide solution, sodium hydroxide solution, sodium bicarbonate solution or ammonia water. Said mixture is for example the mixture of potassium hydroxide solution and sodium hydroxide solution, the mixture of sodium bicarbonate solution and ammoniacal liquor, the mixture of potassium hydroxide solution, sodium hydroxide solution and sodium bicarbonate solution, the mixture of ammoniacal liquor and potassium hydroxide solution .

Preferably, the pH regulator is sodium hydroxide or/and potassium hydroxide.

A kind of preparation method of low viscosity polyvinyl butyral resin, described method comprises the steps:

(1') Fully dissolve PVA in deionized water at 90-98°C to obtain a PVA aqueous solution with a concentration of 7-12wt%;

(2') Add a pH regulator to the temperature of the solution obtained in step (1'), adjust the pH value of the solution to 9-11, and then add a degradation agent and an accelerator to fully degrade the PVA;

(3') Adjust the temperature of the solution obtained in step (2') to 30-40°C and then add an emulsifier;

(4') Adjust the temperature of the solution obtained in step (3') to 0-5°C, then add acid catalyst, n-butyraldehyde and antioxidant to carry out acetalization reaction, and react at constant temperature for 1-2 hours;

(5') Gradually heat up the solution obtained in step (4') to 30-40°C, and keep the temperature constant for 2-3 hours;

(6') Centrifuge and dehydrate the solution obtained in step (5'), add alkali solution to stabilize it for 2-3 hours, control the pH value within the range of 9-10, and then wash it twice with deionized water at 50-60°C , and finally fully washed with deionized water at room temperature and then dried to obtain a white powdery low-viscosity polyvinyl butyral resin.

Preferably, the raw materials used in the method are composed of:

The balance is polyvinyl alcohol.

The weight percentage of n-butyraldehyde is, for example, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%.

The weight percentage of the acid catalyst is, for example, 7.5%, 8%, 8.5%, 9%, 9.5%, 10%, 10.5%, 11%, 11.5%.

The weight percentage of the emulsifier is, for example, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%.

The weight percentage of the antioxidant is, for example, 0.07%, 0.09%, 0.11%, 0.13%, 0.15%, 0.17%, 0.19%.

The weight percentage of the degradation agent is, for example, 3.4%, 3.8%, 4.2%, 4.6%, 5%, 5.4%, 5.7%.

The weight percentage of the accelerator is, for example, 0.002%, 0.003%, 0.004%, 0.005%, 0.006%, 0.007%, 0.008%, 0.009%.

The weight percentage of the pH regulator is, for example, 0.55%, 0.6%, 0.65%, 0.7%, 0.75%, 0.8%, 0.85%, 0.9%, 0.95%.

The second object of the present invention is to provide a low-viscosity polyvinyl butyral resin prepared by the above method. The low-viscosity polyvinyl butyral resin prepared by the method of the invention has high degree of acetalization, strong cohesive force, high transparency and stable quality.

The third object of the present invention is to provide the use of a low-viscosity polyvinyl butyral resin, which is used in inks, coatings and adhesives.

The low-viscosity polyvinyl butyral resin of the present invention is in the form of white powder, which does not cause the ink to appear variegated, and can have better application in the ink.

The low-viscosity polyvinyl butyral resin in the present invention refers to a polyvinyl butyral resin with a viscosity of 20-40 mPa·s. The viscosity test conditions are: rotational viscosity test, the viscosity measured by 10% PVB ethanol solution at 20°C, and the low viscosity range is 20-40mPa·s. The molecular weight _Mn of the low-viscosity polyvinyl butyral resin is 75000-85000 Daltons.

Compared with the prior art, the present invention has the following beneficial effects:

(1) The present invention successfully prepares low-viscosity PVB resin by adding a degradation agent, and improves production efficiency;

(2) Through the control of formula and process, PVB resin with higher degree of acetalization is obtained, which improves the cohesive force, and the butyraldehyde group of the PVB resin can reach more than 80%;

(3) Through the adjustment of the water washing process, the transparency and quality stability of the PVB resin are improved, and the light transmittance of the PVB resin can reach more than 85%.

Description of drawings

The technical solutions of the present invention will be further described below in conjunction with the accompanying drawings and through specific implementation methods.

Figure 1: Infrared spectra of PVA and PVB.

Detailed ways

For better illustrating the present invention, facilitate understanding technical scheme of the present invention, typical but non-limiting embodiment of the present invention is as follows:

Example 1

A low-viscosity polyvinyl butyral PVB resin is prepared from polyvinyl alcohol PVA, n-butyraldehyde, degradation agent, pH regulator, antioxidant, emulsifier and acid catalyst through acetal reaction.

The concentration of the PVA aqueous solution is 8%.

The raw materials used in the method consist of:

The rest is polyvinyl alcohol.

The method for preparing low-viscosity polyvinyl butyral resin may further comprise the steps:

(1) Fully dissolve 15kg of PVA in deionized water at 90-98°C to obtain a PVA aqueous solution with a concentration of 8%;

(2) Add 0.13kg of sodium hydroxide to the solution obtained in step (1), adjust the pH value of the solution at 9-11, then add 0.80kg of sodium hypochlorite and 0.0027kg of accelerator to fully degrade PVA;

(3) After adjusting the temperature of the solution obtained in step (2) to 30-40°C, add 0.027kg of sodium lauryl sulfate;

(4) After adjusting the temperature of the solution obtained in step (3) to 0-5°C, add 2.13kg of dilute hydrochloric acid with a concentration of 30%, 8.0kg of n-butyraldehyde and 0.027kg of antioxidant 1010 to carry out acetalization reaction and keep the temperature constant Reaction 1～2h;

(5) Gradually raise the temperature of the solution obtained in step (4) to 30-40°C, and keep the temperature constant for 2-3 hours;

(6) Centrifuge and dehydrate the solution obtained in step (5), add sodium bicarbonate solution to stabilize it for 2-3 hours, adjust the pH value of the solution within the range of 9-10, and then wash it with deionized water at 50-60°C for 2 Finally, fully wash with deionized water at room temperature and dry to obtain powdery low-viscosity PVB resin.

Example 2

A low-viscosity polyvinyl butyral PVB resin is prepared from polyvinyl alcohol PVA, n-butyraldehyde, degradation agent, pH regulator, antioxidant, emulsifier and acid catalyst through acetal reaction.

The concentration of the PVA aqueous solution is 10%.

The raw materials used in the method consist of:

The rest is polyvinyl alcohol.

The method for preparing low-viscosity polyvinyl butyral resin may further comprise the steps:

(1) Fully dissolve 15kg of PVA in deionized water at 90-98°C to obtain a 10% PVA aqueous solution;

(2) Add 0.18kg sodium hydroxide to the solution obtained in step (1), adjust the pH value of the solution at 9-11, then add 1.19kg sodium hypochlorite and 0.0027kg accelerator to fully degrade PVA;

(3) After adjusting the temperature of the solution obtained in step (2) to 30-40°C, add 0.0299kg of sodium dodecyl sulfate;

(4) After adjusting the temperature of the solution obtained in step (3) to 0-5°C, add 2.99kg of dilute hydrochloric acid with a concentration of 30%, 10.5kg of n-butyraldehyde and 0.0299kg of antioxidant 1076 to carry out acetalization reaction at constant temperature Reaction 1～2h;

(5) Gradually raise the temperature of the solution obtained in step (4) to 30-40°C, and keep the temperature constant for 2-3 hours;

(6) Centrifuge and dehydrate the solution obtained in step (5), add the prepared sodium bicarbonate solution to stabilize it for 2-3 hours, adjust the pH value of the solution within the range of 9-10, and then use a 50-60°C dehydrator to Washed twice with deionized water, and finally fully washed with deionized water at room temperature and then dried to obtain a powdery low-viscosity PVB resin.

Example 3

A low-viscosity polyvinyl butyral PVB resin is prepared from polyvinyl alcohol PVA, n-butyraldehyde, degradation agent, pH regulator, antioxidant, emulsifier and acid catalyst through acetal reaction.

The concentration of the PVA aqueous solution is 10%.

The raw materials used in the method consist of:

The rest is polyvinyl alcohol.

The method for preparing low-viscosity polyvinyl butyral resin may further comprise the steps:

(1) Fully dissolve 15kg of PVA in deionized water at 90-98°C to obtain a 10% PVA aqueous solution;

(2) Add 0.21 kg of potassium hydroxide to the solution obtained in step (1), adjust the pH value of the solution in the range of 9 to 11, then add 1.39 kg of hydrogen peroxide and 0.0027 kg of accelerator to fully degrade PVA;

(3) After adjusting the temperature of the solution obtained in step (2) to 30-40°C, add 0.035kg of sodium dodecylbenzenesulfonate;

(4) After adjusting the temperature of the solution obtained in step (3) to 0-5°C, add 4.2kg of dilute hydrochloric acid with a concentration of 30%, 13.9kg of n-butyraldehyde and 0.035kg of antioxidant 1076 to carry out acetalization reaction and keep the temperature constant Reaction 1～2h;

(5) Gradually raise the temperature of the solution obtained in step (4) to 30-40°C, and keep the temperature constant for 2-3 hours;

(6) Centrifuge and dehydrate the solution obtained in step (5), add the prepared sodium hydroxide solution for stabilization for 2 to 3 hours, adjust the pH value of the solution within the range of 9 to 10, and then use 50 to 60 ° C to remove Washed twice with deionized water, and finally fully washed with deionized water at room temperature and then dried to obtain powdered PVB resin.

The properties of the low-viscosity polyvinyl butyral resin prepared by the above-mentioned method are shown in the following table:

Example 4

A kind of preparation method of low viscosity polyvinyl butyral resin, described method comprises the steps:

(1) Fully dissolve PVA in deionized water at 90-98°C to obtain a PVA aqueous solution with a concentration of 7wt%;

(2) Add a pH regulator to the temperature of the solution obtained in step (1) to adjust the pH value of the solution to 9-11, and then add degradation agent hydrogen peroxide and accelerator to fully degrade PVA;

(3) After adjusting the temperature of the solution obtained in step (2) to 30-40°C, add the emulsifier sodium dodecylsulfonate;

(4) Adjust the temperature of the solution obtained in step (3) to 0-5°C, then add dilute hydrochloric acid, n-butyraldehyde, and antioxidant 168 as an acid catalyst with a mass fraction of 30%, and carry out acetalization reaction. 2h;

(5) Gradually raise the temperature of the solution obtained in step (4) to 30-40°C, and keep the temperature constant for 2-3 hours;

(6) Centrifuge and dehydrate the solution obtained in step (5), add alkaline solution potassium hydroxide solution to stabilize for 2-3 hours, control the pH value within the range of 9-10, and then wash with deionized water at 50-60 °C 2 times, and finally fully washed with deionized water at room temperature and then dried to obtain a powdery low-viscosity polyvinyl butyral resin.

The raw materials used in the method consist of:

The balance is polyvinyl alcohol.

Example 5

A kind of preparation method of low viscosity polyvinyl butyral resin, described method comprises the steps:

(1) Fully dissolve PVA in deionized water at 90-98°C to obtain a PVA aqueous solution with a concentration of 12wt%;

(2) Add a pH regulator to the temperature of the solution obtained in step (1) to adjust the pH value of the solution to 9-11, then add the degradation agent sodium hypochlorite and accelerator to fully degrade PVA;

(3) After adjusting the temperature of the solution obtained in step (2) to 30-40°C, add the emulsifier sodium dodecylsulfonate;

(4) Adjust the temperature of the solution obtained in step (3) to 0-5°C, then add acid catalyst dilute hydrochloric acid with a mass fraction of 30%, n-butyraldehyde and antioxidant DLTDP to carry out acetalization reaction, constant temperature reaction 1~ 2h;

(5) Gradually raise the temperature of the solution obtained in step (4) to 30-40°C, and keep the temperature constant for 2-3 hours;

(6) Centrifuge and dehydrate the solution obtained in step (5), add alkaline solution and ammonia water to stabilize for 2 to 3 hours, control the pH value within the range of 9 to 10, and then wash it twice with deionized water at 50 to 60°C. Finally, it is fully washed with deionized water at normal temperature and then dried to obtain a powdery low-viscosity polyvinyl butyral resin.

The raw materials used in the method consist of:

The balance is polyvinyl alcohol.

The properties of the low-viscosity polyvinyl butyral resin prepared by the above-mentioned method are shown in the following table:

As shown in Figure 1 is the infrared spectrum of PVA and PVB, by this infrared spectrum figure, can prove that the reaction generation product of the present invention is really PVB.

From the structural analysis, the main difference between PVA and PVB is: the content of hydroxyl groups in PVB resin is obviously less, and at the same time, a large number of butyral functional groups have appeared in the resin, and COC bonds have been added. It is shown in the infrared spectrum. It can be clearly seen from Figure 1 that the difference is that PVB has a strong absorption bee, that is, the absorption peak of COC near 1054cm ^-1 and 1150cm ^-1 , indicating that COC has appeared in the obtained resin and has been successfully carried out. Acetalization reaction. However, the absorption peak of PVA resin is not obvious in the corresponding position. The common points of the two infrared spectra are that both of them have a strong -OH absorption peak around 3450cm ^-1 , both have CH stretching vibration peaks around 2956cm ^-1 , and the carbonyl C=O absorption peak appears at 1736cm Near ^-1 , it shows that in addition to forming certain acetal groups, PVB resin also contains certain alcoholic hydroxyl groups and vinyl acetate groups.

It should be noted and understood that various modifications and improvements can be made to the invention described in detail above without departing from the spirit and scope of the invention as claimed in the appended claims. Accordingly, the scope of the claimed technical solution is not limited by any particular exemplary teaching given.

The applicant declares that the present invention illustrates the detailed methods of the present invention through the above-mentioned examples, but the present invention is not limited to the above-mentioned detailed methods, that is, it does not mean that the present invention can only be implemented depending on the above-mentioned detailed methods. Those skilled in the art should understand that any improvement of the present invention, the equivalent replacement of each raw material of the product of the present invention, the addition of auxiliary components, the selection of specific methods, etc., all fall within the scope of protection and disclosure of the present invention.

Claims (29)

1. a kind of preparation method of low-viscosity polyvinyl butyral resin is characterized in that, described method adopts two-step precipitation method, the pH value of regulating polyvinyl alcohol aqueous solution is 9～11, adds degradation agent and promotor, Then adjust the temperature of polyvinyl alcohol aqueous solution to be 0～5 ℃, add acid catalyst and n-butyraldehyde, carry out acetalization reaction, obtain low-viscosity polyvinyl butyral resin; the butyral group of described polyvinyl butyral resin reaches More than 80%. 2. The method according to claim 1, characterized in that the method comprises the steps of: (1) Polyvinyl alcohol is dissolved in water to obtain an aqueous solution of polyvinyl alcohol; (2) adjust the pH value of polyvinyl alcohol aqueous solution to be 9～11, and add degradation agent and accelerator; (3) adding emulsifier in the polyvinyl alcohol aqueous solution that step (2) obtains; (4) adjusting the temperature of the polyvinyl alcohol aqueous solution obtained in step (3) to be 0 to 5° C., and adding an acid catalyst, n-butyraldehyde and an antioxidant to carry out an acetalization reaction; (5) gradually warming up to reaction temperature, reaction; (6) Dehydrating the reaction product, stabilizing it with an alkali solution, washing it with water, and drying it to obtain a white powdery low-viscosity polyvinyl butyral resin. 3. The method according to claim 2, characterized in that polyvinyl alcohol is dissolved in water at a temperature not exceeding 98°C. 4. The method according to claim 3, characterized in that polyvinyl alcohol is dissolved in water at 90-98°C. 5. The method according to claim 2, characterized in that the concentration of the polyvinyl alcohol aqueous solution in step (1) is 7-12 wt%. 6. The method according to claim 5, characterized in that the concentration of the polyvinyl alcohol aqueous solution in step (1) is 8-11 wt%. 7. The method according to claim 2, characterized in that, by adding a pH regulator to the aqueous polyvinyl alcohol solution obtained in step (1) to adjust the pH value. 8. The method according to claim 2, characterized in that the emulsifier is added after the temperature of the polyvinyl alcohol aqueous solution obtained in step (2) is adjusted to 30-40°C. 9. The method according to claim 8, characterized in that the emulsifier is added after adjusting the temperature of the polyvinyl alcohol aqueous solution obtained in step (2) to 32-38°C. 10. The method according to claim 2, characterized in that the time for the acetalization reaction in step (4) is 1 to 2 hours. 11. The method according to claim 10, characterized in that the time for the acetalization reaction in step (4) is 1.05 to 1.95 hours. 12. The method according to claim 11, characterized in that the time for the acetalization reaction in step (4) is 1.15 to 1.85 hours. 13. The method according to claim 2, characterized in that the reaction temperature in step (5) is 30-40°C. 14. The method according to claim 13, characterized in that the reaction temperature in step (5) is 31.5-38.5°C. 15. The method according to claim 14, characterized in that the reaction temperature in step (5) is 32.5-37.5°C. 16. The method according to claim 2, characterized in that the reaction time in step (5) is 2-3 hours. 17. The method according to claim 16, characterized in that the reaction time in step (5) is 2.15-2.85 hours. 18. The method according to claim 17, characterized in that the reaction time in step (5) is 2.25-2.75 hours. 19. The method according to claim 2, characterized in that, in step (6), after the reaction product is centrifuged and dehydrated, an alkaline solution is added for stabilization treatment for 2 to 3 hours, the pH value is controlled within 9 to 10, and then 50 to 60 The deionized water at ℃ was washed twice, and finally washed with deionized water at room temperature and dried to obtain a powdery low-viscosity polyvinyl butyral resin. 20. The method according to claim 2, wherein the acid catalyst is selected from any one of dilute hydrochloric acid, dilute sulfuric acid or dilute phosphoric acid or a mixture of at least two. 21. The method according to claim 2, wherein the emulsifier is selected from any one of sodium lauryl sulfate, sodium dodecylsulfonate or sodium dodecylbenzenesulfonate or A mixture of at least two. 22. The method according to claim 2, wherein the antioxidant is selected from any one of antioxidant 1010, antioxidant 168, antioxidant DLTDP, antioxidant 1076 or antioxidant 1024 one or a mixture of at least two. 23. The method according to claim 2, wherein the degradation agent is sodium hypochlorite or/and hydrogen peroxide. 24. The method according to claim 2, wherein the alkaline solution is any one of potassium hydroxide solution, sodium hydroxide solution, sodium bicarbonate solution or ammonia water or a mixture of at least two. 25. The method according to claim 7, wherein the pH regulator is sodium hydroxide or/and potassium hydroxide. 26. The method of claim 1, further comprising the steps of: (1') fully dissolving PVA in deionized water at 90-98° C. to obtain a PVA aqueous solution with a concentration of 7-12 wt %; (2') add pH adjusting agent in the solution that step (1') obtains, regulate solution pH value at 9～11, then add degradation agent and promotor and make PVA fully degrade; (3') adding emulsifier after adjusting the temperature of the solution obtained in step (2') to 30-40°C; (4') Adjust the temperature of the solution obtained in step (3') to 0-5°C, then add acid catalyst, n-butyraldehyde and antioxidant, carry out acetalization reaction, and react at constant temperature for 1-2 hours; (5') The solution obtained in step (4') is gradually warmed up to 30～40°C, and kept at a constant temperature for 2～3h; (6') Centrifuge and dehydrate the solution obtained in step (5'), add an alkali solution to stabilize it for 2-3 hours, control the pH value within the range of 9-10, and then wash it twice with deionized water at 50-60°C , and finally fully washed with deionized water at room temperature and then dried to obtain a white powdery low-viscosity polyvinyl butyral resin. 27. The method of claim 1, wherein the raw materials used in the method are composed of: 28. A low-viscosity polyvinyl butyral resin, characterized in that the low-viscosity polyvinyl butyral resin is prepared by the method according to any one of claims 1-27. 29. A use of the low-viscosity polyvinyl butyral resin as claimed in claim 28, characterized in that the low-viscosity polyvinyl butyral resin is used in inks, coatings and adhesives.