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Copromoters for UPR

Arxada, formerly Lonza, offers a wide range of intermediate chemistries, including diketene derivatives. Diketene derivatives have an important use as copromoters in polyester resin manufacturing.

Unsaturated Polyester Resin

Unsaturated polyester resin (UPR) is used across a wide variety of industries, from fiberglass reinforced plastics (FRP) to construction materials and marine coatings. Because of its excellent mechanical properties, corrosion resistance, and ease of processing, UPR is a versatile and desirable resin. UPR can also act as a matrix material in composites, where it is reinforced with fibers such as fiberglass, carbon fiber, or aramid. The addition of UPR in composites results in enhanced strength, stiffness and durability. However, unsaturated polyester resins are inherently limited by their poor impact resistance, thermal stability, and weatherability, and rely on intermediate additives to enhance performance properties. Copromoters are among the key additives used in UPR production to improve the resin system.


Copromoters function by facilitating the polymerization process and modifying the molecular structure of the polyester matrix. They commonly act as reactive diluents, co-monomers, or modifiers, influencing the crosslinking density, curing kinetics, and final properties of the resin.

A key function of copromoters is controlling the viscosity of the resin, ensuring optimal flow characteristics during processing. By regulating viscosity, copromoters facilitate uniform distribution of UPR within composite systems, thereby enhancing interfacial adhesion and mechanical properties. Copromoters also help prevent shrinkage and internal stresses during curing, resulting in improved dimensional stability and reducing cracking and warping. Moreover, copromoters can influence the cure times and exothermic behavior of the resin system, giving formulators greater control over processing parameters and reducing the risk of defects in the final product.

Copromoters not only improve the processability of the resin but also impart desirable attributes like flexibility, toughness, and thermal stability to the cured composite. Copromoters promote crosslinking reactions within unsaturated polyesters, thereby improving the strength, stiffness, and chemical resistance of the cured composite. By copolymerizing with the base polyester resin, copromoters introduce additional crosslinking sites to create unique resins with enhanced performance attributes.

There are a multitude of copromoters used in UPR formulations, including styrene, vinyl toluene, unsaturated monomers, and diketene derivatives. Arxada is a leading manufacturer of diketene derivative co-promoters for unsaturated polyester resins.

Arxada Diketene Derivatives

Diketene derivatives are widely used as copromoters in the production and modification of unsaturated polyester resins. Arxada offers several diketene chemistries that provide versatility, simplify processing, and enhance performance.
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