A kind of manufacturing method of polyester chip for heat shrinkable film

Abstract

The invention discloses a preparation method for polyester slices for a heat shrinkable film; with terephthalic acid, modified diol, ethylene glycol and modified dibasic acid as main materials, underthe action of compound auxiliary agents, the polyester slices are obtained by step-by-step beating, low temperature step-by-step esterification, condensation polymerization and grain-sized dicing. Themodified copolyester produced by the method has the advantages of excellent hue, good heat shrinkage, short melting range and small difference between product batches.

Description

technical field [0001] The invention discloses a method for making a special polyester chip for heat-shrinkable films, and belongs to the field of copolymerized modified polyester production. Background technique [0002] Heat shrinkable film is widely used in the packaging industry of beverages and daily necessities, etc., and it is mainly made of PVC and PS. PVC heat-shrinkable film has the characteristics of high transparency, good gloss, and high shrinkage rate. However, since beverage bottles are mostly made of PET, the PVC label needs to be removed during regeneration. The process is cumbersome, and there is a problem of available chlorine, which directly affects environmental protection. PS heat-shrinkable label film also has a cumbersome regeneration process. At present, polyester products (PETG) modified by 1,4-cyclohexanedimethanol (PETG) are very suitable for the preparation of heat shrinkable films, but because of its raw and auxiliary materials 1,4-cyclohexaned...

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Problems solved by technology

Such as patent CN102807669A discloses a kind of introduction of the second modified monomer dicarboxylic acid on the basis of neopentyl glycol monomer modified PET to improve the thermal shrinkage of neopentyl glycol single modified monomer, and by introducing Melt enhancer, which makes the copolyester molecules branched and partially crosslinked polyester viscosity and strength, but in the production process of the modified polyester, due to the high esterification temperature, there are many side reactions, which seriously affect the hue of the product

Patent CN104327256A discloses a production process of polyester chips for modified heat-shrinkable films, which adopts a three-pot process: esterification→precondensation→final polycondensation, and optimizes the processes of each point to produce slices with good heat shrinkability, high intrinsic viscosity, and hue Good, uniform quality, but in the actual production process, the esterification of neopentyl glycol is relatively slower than that of ethylene glycol, and it is difficult for neopentyl glycol to be completely blocked into the molecular chain, resulting in thermal shrinkage of products between batches The performance varies greatly, which is mainly due to the different content of neopentyl glycol contained in the products between batches. In addition, because most of the neopentyl glycol is released from the polycondensation tank during the polycondensation process, the follow-up processing costs are increased, and Not environmentally friendly

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