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Where Is the Vacuum Used in the Preparation of PBAT for Degraded Plastics

Where is the vacuum used in the preparation of PBAT for degraded plastics? Read on and you’ll understand!

Driven by environmental policies, most countries around the world have now started to restrict the use of traditional plastics, enterprises responded one after another, PLA, PBAT, PHA, PCL, PBS and other biodegradable plastics in disposable tableware, packaging, agriculture, automotive, medical, textile and other fields of application is ushering in new opportunities for market development. As an important member of biodegradable plastics, PBAT has attracted much attention in recent years due to its high cost performance, and its industrialization technology and preparation process are becoming more and more mature. Today, let’s get to know the “celebrity” of biodegradable plastics: PBAT.

Where is the vacuum used in the preparation of PBAT for degraded plastics - Vacculex

What is PBAT

PBAT is polybutylene terephthalate-adipate, which is a thermoplastic biodegradable plastic. It is a copolymer of butylene adipate and butylene terephthalate, so it has the characteristics of both PBA and PBT, with good ductility and elongation at break, as well as good heat resistance and impact properties.

According to the source of biodegradable plastics can be divided into bio-based biodegradable materials and petrochemical-based biodegradable materials, PBAT is one kind of petrochemical-based biodegradable plastics. Because the petroleum-based cost of PBAT is lower, its investment intensity is smaller and it is expected to become the largest biodegradable plastic category in the future.

What is PBAT - Vacculex

Biodegradable plastic raw material source classification, can be in the soil, sand and other natural conditions, and microbial abnormal action degradation into carbon dioxide, water and other small molecules or low molecular compounds.

Basic properties of PBAT

  • PBAT is a semi-crystalline polymer with a crystallization temperature of about 110°C
  • Melting point around 130℃
  • Density is between 1.18g/ml~1.3g/ml
  • Crystallinity around 30%
  • Shore hardness >85

Preparation method of PBAT

The raw materials for the preparation of PBAT are mainly adipic acid (AA), terephthalic acid (PTA) and butanediol (BDO) as monomers, which are synthesized into poly(adipic acid/butanediol terephthalate) through esterification or ester exchange reaction and polycondensation reaction in certain ratio, and then the final product is produced through three steps of esterification, polycondensation and pelletizing.

There are three types of esterification processes: co-esterification, split-esterification and tandem esterification. Among them, co-esterification process only needs one reactor for one esterification reaction, so it has the characteristics of short process flow, high raw material utilization, short reaction time and high production efficiency, which is widely used by chemical enterprises.

PBAT preparation and vacuum technology

Regardless of co-esterification, split-esterification, or tandem esterification, the focus in all three processes is on strict control of the reaction esterification mode, esterification time, condensation temperature, stabilizer, and condensation vacuum. These key factors can directly affect the synthesis process and ultimately the performance of the product.

In the esterification process, in order to reduce the occurrence of side reactions of BDO, reduce the generation of THF and reduce the consumption of raw materials, the whole esterification reaction is carried out under vacuum conditions, and the vacuum environment can reduce the temperature of esterification reaction, which also reduces the energy consumption required for production. Therefore, the development of vacuum technology and equipment has greatly increased the domestic PBAT production capacity.

PBAT preparation and vacuum technology​ - Vacculex

As an example from a customer, Vacculex supplied a total of 18 sets of vacuum units for the 500,000 ton capacity Sinochem Donghua Tianye project. Among them, 6 sets of screw vacuum pumps are used for pre-polymerization, 6 sets of screw vacuum pumps are used for final polycondensation, and another 6 sets of screw vacuum pumps are used for viscosification, providing a stable vacuum environment for PBAT esterification and production.

PBAT preparation and vacuum technology​ - Vacculex

With the expansion of the scope and intensity of “plastic restriction”, biodegradable plastics will usher in a period of rapid development. At present, the global PBAT market demand is strong, the price of PBAT is high, the industry concentration is high, the potential market is large, and the industrialization prospect is good.

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