A process for the preparation of a hydroxyl-terminated polybutadiene

Abstract

The application discloses a preparation method of hydroxyl-terminated polybutadiene, which comprises the following steps: (1) adding an organic solvent and a titanium-silicon molecular sieve into an autoclave, uniformly adding 1,3-butadiene and hydrogen peroxide into the autoclave after temperature rising, and continuing to react for a certain time after the addition; and (2) obtaining the hydroxyl-terminated polybutadiene after centrifugation, water washing and water removal of the product obtained in the step (1). The method overcomes the defects in the prior art, and the obtained hydroxyl-terminated polybutadiene has the characteristics of high yield, high content of cis-1,4 structure and narrow molecular weight distribution.

Description

Technical Field

[0001] This invention relates to the field of chemical technology, specifically to a method for preparing hydroxyl-terminated polybutadiene. Background Technology

[0002] Hydroxyl-terminated polybutadiene (HTPB), commonly known as hydroxyl-terminated rubber, typically has a number-average molecular weight between 1500 and 10000. It possesses advantages such as a low glass transition temperature, good transparency, low viscosity, low volatility, oil and aging resistance, and good processability. Polyurethane elastomers prepared using hydroxyl-terminated HTPB not only exhibit high tensile and adhesive strength but also good oil and water resistance.

[0003] The properties of hydroxyl-terminated polybutadiene are closely related to its molecular chain microstructure (Journal of Macromolecular Science, Part A: Pure and Applied Chemistry, 2013, 50, 128). Based on different microstructures, it can be divided into 1,2-hydroxyl-terminated polybutadiene, cis-1,4-hydroxyl-terminated polybutadiene, and trans-1,4-hydroxyl-terminated polybutadiene. The higher the content of the cis-1,4 structure in the microstructure of hydroxyl-terminated polybutadiene, the lower its viscosity, the better its flowability, and the lower its glass transition temperature. Furthermore, the processed products exhibit superior mechanical properties, especially low-temperature mechanical properties.

[0004] Free radical polymerization using hydrogen peroxide as an initiator is one of the commonly used methods for producing hydroxyl-terminated polybutadiene. However, this method has disadvantages such as low yield of hydroxyl-terminated polybutadiene (<60%), low content of cis-1,4 structure in the microstructure of hydroxyl-terminated polybutadiene, and wide molecular weight distribution of hydroxyl-terminated polybutadiene. Summary of the Invention

[0005] To address the aforementioned technical problems, the present invention aims to provide a method for preparing hydroxyl-terminated polybutadiene. This method overcomes the shortcomings of the prior art, and the obtained hydroxyl-terminated polybutadiene has the characteristics of high yield, high content of cis-1,4 structure, and narrow molecular weight distribution.

[0006] To achieve the above-mentioned technical objectives and effects, the present invention is implemented through the following technical solution:

[0007] A method for preparing hydroxyl-terminated polybutadiene includes the following steps:

[0008] (1) Add organic solvent and titanium silicon molecular sieve into high pressure vessel, heat up, and then add 1,3-butadiene and hydrogen peroxide into high pressure vessel at a uniform rate. After the addition is complete, continue the reaction for a certain period of time.

[0009] (2) The product obtained in step (1) is centrifuged, washed with water and dehydrated to obtain hydroxyl-terminated polybutadiene.

[0010] Preferably, the organic solvent is at least one of isopropanol, methanol, and ethanol.

[0011] Preferably, the titanium-silicon molecular sieve is one of TS-1, TS-2, Ti-CHA, and Ti-Y molecular sieves, and the titanium content is 2-5%.

[0012] Preferably, the concentration of the hydrogen peroxide is 20% to 50%.

[0013] Furthermore, in step (1), after heating to 105-130°C, 1,3-butadiene and hydrogen peroxide are added; after adding 1,3-butadiene and hydrogen peroxide, the reaction continues for 1-3 hours.

[0014] Furthermore, in step (1), the mass ratio of organic solvent, titanium silicate molecular sieve, 1,3-butadiene and hydrogen peroxide is 1000:1~5:1000~3000:1~10.

[0015] Furthermore, in step (1), the addition time of 1,3-butadiene and hydrogen peroxide is 0.5 to 2 hours.

[0016] Furthermore, in step (2), the dehydration conditions are vacuum treatment at 50-80°C for 6-12 hours.

[0017] The beneficial effects of this invention are:

[0018] In the preparation method of this invention, a titanium-silicon molecular sieve is added. As a heterogeneous catalyst, the titanium-silicon molecular sieve can activate H₂O₂ to generate hydroxyl radicals. Compared to the generation of hydroxyl radicals from H₂O₂ upon heating, the activation of H₂O₂ using titanium-silicon molecular sieve catalysis can generate hydroxyl radicals more effectively and controllably, resulting in hydroxyl-terminated polybutadiene with high yield, high content of cis-1,4 structure, and narrow molecular weight distribution. Furthermore, the titanium-silicon molecular sieve is a solid and can be recycled and reused after the reaction. Detailed Implementation

[0019] The technical solutions of the present invention will be clearly and completely described below with reference to specific embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] This invention provides a method for preparing hydroxyl-terminated polybutadiene, comprising the following steps:

[0021] (1) Add the organic solvent and titanium-silicon molecular sieve into the autoclave, heat to 105-130℃, and then add 1,3-butadiene and hydrogen peroxide into the autoclave at a constant rate over a period of 0.5-2 hours. After the addition is complete, continue the reaction for 1-3 hours. In step (1), the organic solvent is at least one of isopropanol, methanol, and ethanol; the titanium-silicon molecular sieve is one of TS-1, TS-2, Ti-CHA, and Ti-Y molecular sieves, with a titanium content of 2-5%; and the concentration of hydrogen peroxide is 20%-50%.

[0022] In step (1), the mass ratio of organic solvent, titanium silicate molecular sieve, 1,3-butadiene and hydrogen peroxide is 1000:1~5:1000~3000:1~10;

[0023] (2) The product obtained in step (1) is centrifuged, washed with water and dehydrated to obtain hydroxyl-terminated polybutadiene. The dehydration conditions are vacuum treatment at 50-80°C for 6-12 hours.

[0024] The present invention will be further described in detail below through specific embodiments.

[0025] Example 1

[0026] (1) Isopropanol and TS-1 molecular sieve were added to the autoclave at a mass ratio of 1000:1. After heating to 115°C, 1,3-butadiene and hydrogen peroxide were added to the autoclave at a mass ratio of 1000:1000:5. After the addition was completed, the reaction continued for 3 hours. The titanium content of TS-1 molecular sieve was 3.5%, the concentration of hydrogen peroxide was 30%, and the addition time of 1,3-butadiene and hydrogen peroxide was 1.5 hours.

[0027] (2) The product obtained in step (1) is centrifuged, washed with water and dehydrated to obtain the product end-hydroxyl polybutadiene; wherein the dehydration condition is vacuum treatment at 50°C for 12 hours.

[0028] Example 2

[0029] (1) Add methanol and TS-2 molecular sieve to a high-pressure reactor at a mass ratio of 1000:5. After heating to 105℃, add 1,3-butadiene and hydrogen peroxide to the high-pressure reactor at a mass ratio of 1000:2500:10. Continue the reaction for 2 hours after the addition is complete. The titanium content of TS-2 molecular sieve is 2%, the concentration of hydrogen peroxide is 20%, and the addition time of 1,3-butadiene and hydrogen peroxide is 2 hours.

[0030] (2) The product obtained in step (1) is centrifuged, washed with water and dehydrated to obtain the product end-hydroxyl polybutadiene; wherein the dehydration condition is vacuum treatment at 80°C for 6 hours.

[0031] Example 3

[0032] (1) Ethanol and Ti-CHA molecular sieve were added to a high-pressure reactor at a mass ratio of 1000:2. After heating to 120°C, 1,3-butadiene and hydrogen peroxide were added to the high-pressure reactor at a mass ratio of 1000:3000:1. After the addition was completed, the reaction continued for 3 hours. The titanium content of Ti-CHA molecular sieve was 5%, the concentration of hydrogen peroxide was 50%, and the addition time of 1,3-butadiene and hydrogen peroxide was 0.5 hours.

[0033] (2) The product obtained in step (1) is centrifuged, washed with water and dehydrated to obtain the product end-hydroxyl polybutadiene; wherein the dehydration condition is vacuum treatment at 60°C for 8 hours.

[0034] Example 4

[0035] (1) Methanol and Ti-Y molecular sieve were added to a high-pressure reactor at a mass ratio of 1000:2. After heating to 130°C, 1,3-butadiene and hydrogen peroxide were added to the high-pressure reactor at a mass ratio of 1000:1000:5. After the addition was completed, the reaction continued for 3 hours. The titanium content of Ti-Y molecular sieve was 3%, the concentration of hydrogen peroxide was 30%, and the addition time of 1,3-butadiene and hydrogen peroxide was 1 hour.

[0036] (2) The product obtained in step (1) is centrifuged, washed with water and dehydrated to obtain the product end-hydroxyl polybutadiene; wherein the dehydration condition is vacuum treatment at 50°C for 12 hours.

[0037] Comparative Example 1

[0038] (1) Isopropanol, 1,3-butadiene and hydrogen peroxide were added to a high-pressure reactor in a mass ratio of 1000:1000:5, and the mixture was heated to 115°C and reacted for 3 hours; the concentration of hydrogen peroxide was 30%.

[0039] (2) The product obtained in step (1) is washed with water and dehydrated to obtain the product end-hydroxyl polybutadiene; wherein the dehydration condition is vacuum treatment at 50°C for 12 hours.

[0040] Comparative Example 2

[0041] (1) Isopropanol was added to the autoclave and heated to 115°C. Then, 1,3-butadiene and hydrogen peroxide were added to the autoclave at a uniform rate according to the mass ratio of isopropanol, 1,3-butadiene and hydrogen peroxide of 1000:1000:5. After the addition was completed, the reaction continued for 3 hours. The concentration of hydrogen peroxide was 30%, and the addition time of 1,3-butadiene and hydrogen peroxide was 1.5 hours.

[0042] (2) The product obtained in step (1) is washed with water and dehydrated to obtain the product end-hydroxyl polybutadiene; wherein the dehydration condition is vacuum treatment at 50°C for 12 hours.

[0043] The hydroxyl value, yield, cis-1,4 structure content, and molecular weight distribution of the terminal hydroxyl polybutadiene in each example and comparative example are shown in Table 1.

[0044] Table 1

[0045]

[0046] As shown in Table 1, compared with Comparative Example 1 and Comparative Example 2, the hydroxyl-terminated polybutadiene in Examples 1-4 of the present invention has the characteristics of high yield, high content of cis-1,4 structure and narrow molecular weight distribution.

[0047] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any modifications or equivalent transformations made based on the content of the present invention specification, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A method for preparing hydroxyl-terminated polybutadiene, characterized in that, Includes the following steps: (1) Add the organic solvent and titanium-silicon molecular sieve into the autoclave, heat up, and then add 1,3-butadiene and hydrogen peroxide into the autoclave at a uniform rate. After the addition is complete, continue the reaction for a certain period of time. The titanium-silicon molecular sieve is one of TS-1, TS-2, Ti-CHA, and Ti-Y molecular sieves, and the titanium content is 2-5%. (2) The product obtained in step (1) is centrifuged, washed with water and dehydrated to obtain hydroxyl-terminated polybutadiene.

2. The method for preparing hydroxyl-terminated polybutadiene according to claim 1, characterized in that, The organic solvent is at least one of isopropanol, methanol, and ethanol.

3. The method for preparing hydroxyl-terminated polybutadiene according to claim 1, characterized in that, The concentration of the hydrogen peroxide is 20% to 50%.

4. The method for preparing hydroxyl-terminated polybutadiene according to claim 1, characterized in that, In step (1), after heating to 105~130℃, 1,3-butadiene and hydrogen peroxide are added; after adding 1,3-butadiene and hydrogen peroxide, the reaction continues for 1~3 hours.

5. The method for preparing hydroxyl-terminated polybutadiene according to claim 1, characterized in that, In step (1), the mass ratio of organic solvent, titanium silicate molecular sieve, 1,3-butadiene and hydrogen peroxide is 1000:1~5:1000~3000:1~10.

6. The method for preparing hydroxyl-terminated polybutadiene according to claim 1, characterized in that, In step (1), the addition time of 1,3-butadiene and hydrogen peroxide is 0.5 to 2 hours.

7. The method for preparing hydroxyl-terminated polybutadiene according to claim 1, characterized in that, In step (2), the dehydration conditions are vacuum treatment at 50~80℃ for 6~12 hours.

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