Method for preparing high-polymerization-degree polyvinyl alcohol through solution polymerization
A technology of polyvinyl alcohol and high degree of polymerization, which is applied in the field of preparation of polyvinyl alcohol, can solve the problems that polyvinyl alcohol is difficult to achieve high degree of polymerization, and achieve the effects of easy industrial production, high product purity and short polymerization time
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Embodiment 1
[0021] The present embodiment prepares high degree of polymerization polyvinyl alcohol as follows:
[0022] Step 1. Add 400mL of vinyl acetate and 85.1mL of tert-butanol to a 1000mL four-necked flask equipped with a stirrer, reflux condenser, thermometer and nitrogen protection device, raise the temperature to 50°C, and then add 2.82mL of % NPP methanol solution, react for 1h. Add 0.03 g of sorbic acid after the reaction, stop heating, and cool to room temperature to obtain a polyvinyl acetate solution.
[0023] Step 2. Under vacuum, continuously feed methanol into the polyvinyl acetate solution obtained through polymerization, and distill at 60° C. until the unreacted vinyl acetate in the solution is removed to obtain an alcoholic solution of polyvinyl acetate.
[0024] Step 3. Add a methanol solution of NaOH with a mass concentration of 45 g / L to the alcohol solution of polyvinyl acetate obtained in step 2 (the molar ratio of NaOH to polyvinyl acetate is 0.02:1), and alcoho...
Embodiment 2
[0026] The present embodiment prepares high degree of polymerization polyvinyl alcohol as follows:
[0027] Step 1. Add 400mL vinyl acetate and 72.3mL tert-butanol to a 1000mL four-necked flask equipped with a stirrer, reflux condenser, thermometer and nitrogen protection device, raise the temperature to 50°C, and then add 3.13mL containing 1.2 % BPV methanol solution, react for 2h. Add 0.05 g of sorbic acid after the reaction, stop heating, and cool to room temperature to obtain a polyvinyl acetate solution.
[0028] Step 2. Under vacuum, continuously feed methanol into the polyvinyl acetate solution obtained through polymerization, and distill at 60° C. until the unreacted vinyl acetate in the solution is removed to obtain an alcoholic solution of polyvinyl acetate.
[0029] Step 3. Add a methanol solution of NaOH with a mass concentration of 45 g / L to the alcohol solution of polyvinyl acetate obtained in step 2 (the molar ratio of NaOH to polyvinyl acetate is 0.02:1), and ...
Embodiment 3
[0031] The present embodiment prepares high degree of polymerization polyvinyl alcohol as follows:
[0032] Step 1. Add 400mL vinyl acetate and 89.6mL tert-butanol to a 1000mL four-necked flask equipped with a stirrer, reflux condenser, thermometer and nitrogen protection device, raise the temperature to 46°C, and then add 1.89mL containing 1.0 % NPP methanol solution, reacted for 3h. Add 0.02 g of sorbic acid after the reaction, stop heating, and cool to room temperature to obtain a polyvinyl acetate solution.
[0033] Step 2. Under vacuum, continuously feed methanol into the polyvinyl acetate solution obtained through polymerization, and distill at 60° C. until the unreacted vinyl acetate in the solution is removed to obtain an alcoholic solution of polyvinyl acetate.
[0034] Step 3. Add a methanol solution of NaOH with a mass concentration of 45 g / L to the alcohol solution of polyvinyl acetate obtained in step 2 (the molar ratio of NaOH to polyvinyl acetate is 0.02:1), an...
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Abstract
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