Technique for preparing polyester polyol

Abstract

The invention relates to a technique for preparing polyester polyol. The technique mainly comprises the steps of rapid heating esterification, normal-pressure catalysis and micromolecule dihydric alcohol supplement which are conducted synchronously for alcohol to acid ratio stabilization, pressure reduction condensation polymerization and pressure reduction cooling. Total reaction time is 12-15 hours. By the adoption of the technique, reaction time can be effectively shortened, energy consumption can be reduced, controllability and repeatability are high, the technological process is stable, the problems that in the existing polyester polyol synthesis process, dihydric alcohol loss is serious, reaction time is long, efficiency is low, acid hydroxyl value controllability is poor, and acid regurgitation occurs when temperature reduces are solved, and the synthesized polyester polyol is controllable in acid hydroxyl value, excellent in color and stable in reactivity.

Description

Technical field [0001] The invention relates to a preparation method of a polyol, in particular to a preparation method of a polyester polyol, and belongs to the technical field of chemical material synthesis. Background technique [0002] Polyester polyol has excellent temperature resistance and oil resistance. It is one of the most important raw materials for the synthesis of polyurethane elastomers. The polyurethane elastomer material prepared by reacting with diisocyanate has good wear resistance, high resilience and solvent resistance. Good and other characteristics, it has been widely used in the fields of casters, solvent-resistant rubber rollers, industrial belts, and mining screens. [0003] Chinese patent CN102827364A discloses a production method of polyester polyol, which adopts the method of adding a catalyst before, which has the problems of ineffective hydrolysis of titanate or butyl tin catalysts and low catalytic efficiency of the later transesterification reaction...

AI Technical Summary

Problems solved by technology

[0003] Chinese patent CN102827364A discloses a production method of polyester polyol, which adopts the method of pre-adding catalyst, which has the problems of hydrolysis failure of titanate or butyltin catalyst and low catalytic efficiency of transesterification reaction in the later stage, and the production cycle is long. The hydroxy acid value cannot be simply controlled; Chinese patent CN101050270 discloses a polyester polyol used for synthesizing leather bottom material and its preparation method, but the total production process takes up to 30 hours, the energy consumption is large and the efficiency is low, and when the catalyst is added The selected timing is 5-10mgKOH / g, and it is often necessary to react under reduced pressure for a certain period of time before returning to normal pressure and adding a catalyst, which undoubtedly increases the reaction time and operational difficulty; Chinese patent CN102850535B discloses a method for quickly synthesizing polyester polyols at low pressure In this method, pressurization is used to increase the rate of esterification reaction, and the water generated in the reaction is discharged by releasing the pressure. Although the reaction time of polyester polyol is reduced to a certain extent, the positive pressure is used in the early stage and the negative compression is used in the later stage. The operation is relatively complicated and the stability is poor; Chinese patent CN104987496A discloses a method for removing acid value during the synthesis of polyester polyols. In the patent, the method of adding alkaline alcohol solution to the polyester polyol polymerization kettle is used to reduce the acidity of the system. Although the problem of high acid value or acid reflux in the synthesis process of polyester polyols has been solved to a certain extent, it is necessary to cool down and add alkaline alcohol solution to neutralize the acidic groups in the system, and it is also necessary to heat up and distill to remove the alkali Alcohol solution in neutral alcohol, the operation is complicated and inevitably affects the subsequent application reaction of polyester polyol

[0004] At present, the synthesis process of polyester polyol generally adopts longer reaction time and larger alkyd ratio, that is, there is a large excess of diol, and the method of temperature rise and temperature control is single, resulting in large loss of diol, many side reactions, and reaction. Disadvantages such as long time, high energy consumption, high acid value, and easy yellowing of the product