Preparation method and system of polyhydroxycarboxylate or polyhydroxycarboxylic acid polymer

Abstract

The invention relates to a preparation method and system of a polyhydroxycarboxylate or a polyhydroxycarboxylic acid polymer. The method comprises the following steps: under the action of a catalyst,carrying out a pre-polymerization reaction on a raw material hydroxyl carboxylate monomer and / or hydroxyl carboxylic acid monomer for 0.5-48 h under the conditions that the absolute pressure is 100-600 kPa and the temperature is 100-250 DEG C, and separating reaction byproducts to obtain a pre-polymerization product; reducing the pressure of the pre-polymerization product, carrying out a polymerization reaction for 1-72 h under the conditions that the absolute pressure is 5-20 kPa and the temperature is 130-280 DEG C, and separating reaction byproducts, unreacted monomers and monomer oligomersto obtain an intermediate polymerization product; and reducing the pressure of the intermediate polymerization product, carrying out a final polymerization reaction for 0.5-20 h under the conditionsthat the absolute pressure is 0.1-1 kPa and the temperature is 160-280 DEG C, and separating to obtain the product polyhydroxycarboxylate or polyhydroxycarboxylic acid polymer. The polymer has the advantages of high molecular weight, high preparation method and system efficiency and low energy consumption.

Description

technical field [0001] The invention relates to the field of polymer preparation, in particular to a preparation method and system for polyhydroxycarboxylate or polyhydroxycarboxylate polymer. Background technique [0002] Traditional polymer materials are often difficult to degrade, especially for polymer materials used in packaging and disposable products. The waste disposal methods after use have caused serious environmental pollution problems. [0003] Polyhydroxycarboxylate or polyhydroxycarboxylate is a biodegradable polyester product with good physical and chemical properties. It can be used in packaging and medical fields as a polymer material that can be degraded by the environment or metabolized by the human body. Degradation products are water and carbon dioxide. [0004] There are many synthetic methods of polyhydroxycarboxylates, polyhydroxybutyrate (PHB) through biosynthesis and polylactic acid (PLA) synthesized through ring-opening polymerization have been co...

AI Technical Summary

Problems solved by technology

[0005] However, no matter it is biosynthesis or ring-opening polymerization, they all face the disadvantages of complex process, low yield, low production efficiency and high cost.

The current method of direct polycondensation of hydroxycarboxylate or hydroxycarboxylic acid monomer is a relatively simple method for preparing polyhydroxycarboxylate or polyhydroxycarboxylic acid, but it is impossible to synthesize products with higher molecular weight in the actual production process. It is used to produce low-molecular-weight products, and then use these low-molecular-weight products to depolymerize at high temperature to produce their corresponding cyclic ester monomers, and then obtain high-molecular-weight products by ring-opening polymerization of cyclic esters

[0006] All in all, the existing direct polycondensation method cannot obtain high-molecular-weight polyhydroxycarboxylates or polyhydroxycarboxylic acids that can be directly applied, and it is often followed by long-term solid-state polymerization or the preparation of corresponding cyclic ester monomers for further processing. Only ring-opening polymerization can obtain products with a certain molecular weight. This process is long, inefficient, and consumes a lot of energy. It is difficult to achieve continuous production process, and it will also cause product quality fluctuations due to intermittent production.

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