Preparation method of aromatic flame-retardant polyester polyol

[0028] [Example 1]

[0029] In a 1.5L stainless steel reactor equipped with a stirrer, heater, thermocouple and rectifying column, under nitrogen protection and stirring conditions, 600 g of diethylene glycol, 150 g of imidazole-4,5-dicarboxylic acid, 150 g of imidazole-4,5-dicarboxylic acid, 300 g of terephthalic acid, and tetrabutyl titanate, which accounts for 60 ppm of the total mass of the aforementioned raw materials, is additionally added as a catalyst. Start the reaction, heat up to 220°C under normal pressure and keep it for 6 hours. After detecting the acid value of the product ≤ 30mg KOH / g, reduce the gauge pressure to -80kPa within 2 hours, continue the reaction for 5 hours, cool down and discharge the material to obtain an aromatic flame retardant Polyester polyol. After testing, the acid value of the product was 0.33 mg KOH / g, the hydroxyl value was 244 mg KOH / g, and the oxygen index was 27.2%.

[0030] [Example 2]

[0031] In a 1.5L stainless steel reactor equipped with a stirrer, heater, thermocouple and rectifying column, under nitrogen protection and stirring conditions, 500 g of butanediol, 250 g of imidazole-4,5-dicarboxylic acid, 250 g of 200 g of phthalic anhydride, and triethylamine, which accounts for 20 ppm of the total mass of the aforementioned raw materials, is additionally added as a catalyst. Start the reaction, raise the temperature to 210 °C under normal pressure and keep it for 2 hours. After detecting the acid value of the product ≤ 30mg KOH / g, reduce the gauge pressure to -80kPa within 2 hours, continue the reaction for 6 hours, cool down and discharge the material to obtain an aromatic flame retardant Polyester polyol. After testing, the acid value of the product was 0.76 mg KOH / g, the hydroxyl value was 242 mg KOH / g, and the oxygen index was 29.6%.

[0032] [Example 3]

[0033] In a 1.5L stainless steel reactor equipped with a stirrer, a heater, a thermocouple and a rectifying column, under nitrogen protection and stirring conditions, 550 g of propylene glycol, 250 g of imidazole-4,5-dicarboxylic acid, 250 g of isophthalic acid were successively added. 250 g of formic acid, and tetrabutyl titanate, which accounts for 30 ppm of the total mass of the aforementioned raw materials, is added as a catalyst. Start the reaction, raise the temperature to 180°C under normal pressure and keep it for 4h. After detecting the acid value of the product ≤30mg KOH / g, reduce the gauge pressure to -80kPa within 2h, continue the reaction for 7h, cool down and discharge the material to obtain an aromatic flame retardant Polyester polyol. After testing, the acid value of the product was 0.45 mg KOH / g, the hydroxyl value was 244 mg KOH / g, and the oxygen index was 29.3%.