Difference Between Unsaturated Polyester Resin And Polyester Resin Production Line

Unsaturated polyester resin (UPR): A thermosetting resin containing carbon-carbon double bonds (C=C) in the main chain, which needs to be crosslinked and cured after adding an initiator.

Polyester resin (generally refers to thermoplastic polyesters, such as PET/PEs): Thermoplastic plastic or coating base material that does not contain double bonds and can be melt-processed.

jacket reactor

Difference in Application Scenarios

Application areas	Unsaturated Polyester Resin	Polyester Resin
Fiberglass / composite materials	Main materials	x
Powder coating	x	Saturated type with main resin
Hot melt glue	x	TPU or polyester hot melt glue masterbatch
Gel coat / Artificial stone	Highly reactive, used with initiator	x
Industrial coating / plastic modification	High solid content systems (such as high gloss PU paint)	Can be used for PU coating and plastic toughening

Comparison of Production Line Equipment Difference

Project	Unsaturated Polyester Resin Production Line	Polyester Resin Production Line
Reactor Type	Reactor with heating jacket / inner coil (anti-corrosion)	Jacket heating reactor or sigma mixer
Process Temperature	150-220℃	180-250℃ (higher temperature)
Dilution Steps	Need to be diluted with styrene to form a liquid system	No dilution is required, the product is solid or viscous
Post-processing Equipment	Filter, cooler, vacuum system, storage tank	Extruder, film cooling belt, pelletizer
Environmental Protection Requirements	Styrene has VOC emissions (need condensation recovery)	Less volatiles, relatively environmentally friendly
Control Method	Medium degree of automation, focusing on temperature and acid value control	Higher automation, suitable for high temperature and viscous material speed and shear control

polyester resin production line

Differences Between Production Process

Unsaturated Polyester Resin: The dibasic acid and diol are reacted to form oligomers through esterification reaction, and then styrene monomer is added for dilution to form a cross-linkable liquid resin. The final product of this process is a viscous liquid resin that can be directly filled into barrels or storage tanks for use without melt granulation.

Polyester Resin: Usually, a high-temperature polycondensation process is used to first react terephthalic acid (PTA) and ethylene glycol to form oligomers, and then continue to poltmerize under high temperature vacuum to form high molecular weight polyester. Finally, after melt extrusion, strand drawing, cooling and pelletizing, a solid granular product is obtained. This process not only has higher temperatures, but also must be equipped with strand granulation and drying equipment.