A method for inhibiting polymerization side reactions

Abstract

The invention relates to a method for inhibiting polymerization side reaction. The method is characterized in that when in the process of preparing a polymer by utilizing binary acid I and dihydric alcohol I as the main raw materials, a guide substance is added in the esterifying stage, and the molar ratio of binary acid I to dihydric alcohol I is controlled to be 1: 1.05-1.10; the esterifying reaction is performed under the temperature of 180-240 DEG C, and thus the polymerization side reaction is inhibited; the content of the side reaction product in the final product is not greater than 1.0wt%; the guide substance is an esterifying substance generated through binary acid II and dihydric alcohol II in reaction; binary acid I is different from binary acid II; and dihydric alcohol I is different from dihydric alcohol II or is the same as dihydric alcohol II; the weight-average molecular weight distribution coefficient of the final product is 1.2-1.6; the intrinsic viscosity is 0.60-1.20dL / g; the color and luster degree is not greater than 10. According to the method, side reaction is reduced; the esterifying reaction is quick; the molecular weight distribution of the prepared product is concentrated distribution; few byproducts are produced; the quality is high; and the application prospect is extremely good.

Description

Technical field [0001] The invention belongs to the field of polymer preparation, and relates to a method for inhibiting polymerization side reactions, in particular to a method for adding guides to inhibit polymerization side reactions in an esterification process. Background technique [0002] Polyester refers to the general term for polymers obtained by polycondensation of polyols and polyacids. Mainly refers to polyethylene terephthalate (PET), customarily also includes linear thermoplastic resins such as polybutylene terephthalate (PBT) and polyarylate. It is a class of polymers with excellent properties and a wide range of uses. It has been widely used in fiber, plastic, film and other fields. [0003] The existing polyester preparation methods are mainly based on the direct esterification route, and the esterification reaction is carried out with a relatively large alkyd molar ratio, that is, a large excess of alcohol. For example, the patent CN201510081949.3 discloses th...

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Problems solved by technology

[0004] The larger alkyd molar ratio brings the following problems: 1) under the condition that the existing alkyd molar ratio is 1.2 to 1.5, the dihydric alcohol undergoes self-condensation under high alkyd molarity to generate by-products, which are harmful to polyester The fiber-forming property of polyester causes greater impact, and high molar ratio needs to consume more dibasic alcohol raw materials simultaneously, increases cost; 2) for polyester, the esterification stage is directly related to the quality of final polycondensation product, so prior art Under high alkyd-acid molar ratio, carry out sufficient esterification reaction under the esterification time of more than 3 hours, this very easily causes the generation of side reaction in the esterification process; Polycondensation reaction can produce polyester, and the intrinsic viscosity of the precondensation product is generally above 0.25dL / g, which results in a wide molecular weight distribution of the final polyester, poor processing performance of polyester, and easy to produce Phenomena such as wool, broken ends, waste silk, etc.