A kind of method utilizing pet to synthesize unsaturated polyester resin

Abstract

The invention provides a method for synthesizing unsaturated polyester resin by utilizing PET. The method comprises the following steps that 1, glycerol, dihydric alcohol with the boiling point exceeding 210 DEG C, waste PET and a catalyst are added and stirred at the speed of 250-300 r / min, under nitrogen protection, the temperature is raised to 210 DEG C to carry out a heat preserving reaction, after alcoholysis is carried out on PET completely, the temperature continues to be kept for 1-2 h, and cooling is carried out; 2, the temperature is lowered to below 150 DEG C, unsaturated dicarboxylic anhydrides, monohydric alcohol and residual dihydric alcohol with the boiling point lower than 210 DEG C are added, the temperature is raised to 150 DEG C-155 DEG C for carrying out the heat preserving reaction for 0.5 h, then the temperature is raised to 195 DEG C-200 DEG C step by step to carry out the constant temperature reaction, when the water yield reaches 85-90% of the theoretical amount, vacuumizing is carried out to force water to be drained, and the reaction is carried out until an acid value is smaller than 25 mgKOH / g; 3, the temperature is lowered to 155 DEG C-160 DEG C, a proper quantity of polymerization inhibitor is added, styrene is used for diluting, and cooling and filtering are carried out to obtain a finished unsaturated polyester resin product. According to the method, after being cured, the prepared resin has good toughness and physical strength, overcomes the defect of poor solubility of polyester and styrene, and is economical and environmentally friendly.

Description

technical field [0001] The invention belongs to the field of polymer chemistry, and particularly relates to a method for synthesizing non-polyester resin by utilizing PET. Background technique [0002] Polyethylene terephthalate (PET) is produced by the condensation polymerization of terephthalic acid and ethylene glycol, and is commonly referred to as polyester or PET. PET was successfully developed by British scientists in 1941. In 1949, the United Kingdom took the lead in realizing the industrial production of PET. Because of its excellent application function and high strength, all countries in the world compete to produce it since then. With the continuous growth of PET production and consumption, the amount of waste PET is also increasing. Waste PET has become a big problem of environmental pollution. Although PET waste does not directly cause harm to the environment, due to its large amount of waste and strong resistance to the atmosphere and microorganisms, from the...

AI Technical Summary

Problems solved by technology

For example, for the unsaturated polyester resin synthesized by direct alcoholysis of waste PET with glycol, since PET is polymerized from ethylene glycol and terephthalic acid, these two molecular structural units have the characteristics of symmetry, and then The alcoholysis of PET by ethylene glycol or diethylene glycol has poor compatibility with styrene, and phase separation is easy to occur. Structural diols can improve the compatibility of polyester and styrene, but propylene glycol and 2-methyl-1,3 propanediol are more expensive than other raw materials, resulting in higher resin production costs and difficult to obtain good economic benefits

The polyester synthesized after alcoholysis with dihydric alcohol introduces DCPD molecules into the polyester molecules. Although the compatibility between polyester and styrene has been improved, the control of the synthesis reaction process is relatively complicated, and the temperature control is strict. The final resin appearance is also darker

Polyols (especially glycerin) are used to replace part of glycols for alcoholysis of PET. The number of glycerin hydroxyl groups is more than that of glycols, which makes alcoholysis faster, and glycerol has a wide range of sources and low prices, but glycerol is a triol containing two primary alcohols. The hydroxyl group and a secondary hydroxyl group have different activities. During the synthesis of polyester, a network molecular structure will be formed, which makes the reaction difficult to control. It is easy to produce gel in the later stage, resulting in product scrapping or product quality degradation.

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