CN-119978334-B - Method for synthesizing water-soluble polyester without catalyst

Abstract

The invention relates to a method for synthesizing water-soluble polyester without a catalyst, which comprises the following steps of (1) compounding dicarboxylic acid, dihydric alcohol and dibasic acid salt, wherein (n 1 +n 3 )：n 2 ＝(1.02～3)：1,n 1 ) is the amount of dicarboxylic acid, n 2 is the amount of dihydric alcohol, and n 3 is the amount of dibasic acid salt, (2) carrying out esterification reaction under inert atmosphere at the reaction temperature of 80-220 ℃ for 1-20 h, and (3) carrying out polycondensation reaction under vacuum condition at the reaction temperature of 220-300 ℃ for 1-10 h.

Inventors

• ZHANG HONGJIE
• WANG MIAOMIAO
• LV WANGYANG
• CHEN WENXING

Assignees

• 浙江理工大学

Dates

Publication Date

20260508

Application Date

20250110

Claims (3)

1. 1. A method for catalyst-free synthesis of a water-soluble polyester, comprising the steps of: (1) The material preparation method comprises the steps of preparing materials of dicarboxylic acid, dihydric alcohol and dibasic acid salt, wherein (n 1 + n 3 ）：n 2 ＝（1.02～3）：1,n 1 is the amount of the materials of the dicarboxylic acid, n 2 is the amount of the materials of the dihydric alcohol and n 3 is the amount of the materials of the dibasic acid salt, and the molar ratio of the dicarboxylic acid to the dibasic acid salt is 0.9-60; Wherein the dicarboxylic acid is succinic acid or glutaric acid, the dibasic acid salt is isophthalic acid-5-sodium sulfonate, and the dihydric alcohol comprises one or more of ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, heptanediol, octanediol, nonanediol, decanediol, undecanediol, dodecanediol, tetradecanediol, polyethylene glycol, polypropylene glycol and polytetrahydrofuran; (2) Carrying out esterification reaction in an inert atmosphere, wherein the temperature of the esterification reaction is 80-220 ℃ and the time is 1-20 h; (3) And (3) carrying out polycondensation reaction under the vacuum condition, wherein the temperature of the polycondensation reaction is 200-300 ℃ and the time is 1-10 h.
2. 2. The method according to claim 1, wherein in the step (2), the temperature of the esterification reaction is 130 to 220 ℃ and the time is 6 to 10 hours.
3. 3. The method according to claim 1, wherein in the step (3), the vacuum degree is <30Pa, the temperature of the polycondensation reaction is 220 to 260 ℃ and the time is 2 to 8 hours.

Description

Method for synthesizing water-soluble polyester without catalyst Technical Field The invention belongs to the technical field of polyester synthesis, and particularly relates to a method for synthesizing water-soluble polyester without a catalyst. Background The synthetic polymer material has become an indispensable general material in the modern society because of its light weight, low cost, excellent corrosion resistance and durability, and is widely applied to a plurality of fields such as packaging, construction, transportation, electronics, etc. The materials have good mechanical property, chemical stability and processing convenience, and meet various industrial requirements, so the materials are widely used in daily life. However, most of the raw materials for synthesizing the high molecular materials are derived from petroleum-derived compounds, such as polyethylene PE, polypropylene PP, polyethylene terephthalate PET and the like, and the plastic products bring about environmental sustainability challenges while improving the quality of life. Although these synthetic materials have significant advantages and a wide range of applications in many fields, they also have significant drawbacks. Firstly, the recycling process of the materials is very difficult, and the recycling system is imperfect and the treatment cost is high mainly due to the complex chemical structure and the diversified processing modes. Secondly, most synthetic polymer materials are not naturally degradable in the environment due to extremely long degradation period, and are easy to accumulate in the natural environment for a long time, so that a large amount of plastic garbage is formed. The large amount of untreated plastic wastes not only occupy a large amount of land resources, but also cause serious pollution to natural ecosystems such as water, soil, air and the like, and further form potential threat to the health of wild animals, plants and human beings. Therefore, the non-degradability and difficult recovery of synthetic polymeric materials are significant challenges to current environmental protection and sustainable development. At present, aliphatic polyesters, although having better biodegradability, have a longer degradation period, and are difficult to degrade, especially under unfavorable environmental conditions (such as dry or sterile environments). And aliphatic polyesters generally have low water solubility, are not soluble or have low solubility in water, and are therefore generally unsuitable for water-based applications, which has limited some applications in which water-soluble materials are required. In addition, the synthesis of aliphatic polyesters generally relies on the introduction of metal catalysts to promote the polymerization reaction and increase the molecular weight of the polyester. However, the use of such metal catalysts may result in metal residues of the catalyst, thereby bringing potential risks and hazards to human health and the ecological environment, and this also limits their use in high-end applications. As early as 1929, the precursor Carothers in the field of polymer chemistry has systematically studied the preparation of polyesters by direct polyesterification of dicarboxylic acids and diols in the absence of catalysts, in which the system can promote the increase in molecular weight by autocatalysis of the dicarboxylic acids. However, carothers have encountered significant challenges in maintaining a balanced carboxyl to hydroxyl ratio during polyesterification, which is critical to obtaining high molecular weight polyesters. At the same time, the reduction of the terminal carboxyl groups in the late stage of polyesterification further hampers the success of the synthesis. Subsequently, the industry has adopted transesterification using an excess of alcohol as a synthetic method. This approach helps achieve equimolar ratios between functional groups through exchange of small alcohol molecules. Because of the absence of autocatalytic carboxyl groups and the high activation energy associated with transesterification, heavy metal catalysts are required to improve reaction efficiency. In general, the process of removing the metal catalyst residues from the polyester requires the use of organic solvents, which not only increases the production cost significantly, but may introduce solvent residue problems, thereby creating new environmental and safety hazards. Therefore, how to eliminate the toxic metal catalyst residues in polyesters fundamentally, while keeping the cost to a minimum, remains a significant challenge in the current polyester synthesis. Disclosure of Invention Based on the above-mentioned disadvantages and shortcomings of the prior art, it is an object of the present invention to at least solve one or more of the above-mentioned problems of the prior art, in other words, it is an object of the present invention to provide a catalyst-free process for synthesizing water-