Unsaturated polyester resins

As a manufacturer of fiber-reinforced plastics or as an industrial user, rest assured of the advantages of Gremolith AG's unsaturated polyester resins:

  • Customized to meet your requirements.
  • Filled variants with specific properties.
  • Fire- and flame-retardant settings.
  • Adhesive resins with highest tensile shear strength.
  • Binders for mastics, mortars and fillers.

Unsaturated polyester resins are reactive resins that are synthesized by the polycondensation of diols and dicarboxylic acids. The choice of monomers and the ratios to one another control the properties during processing and of the cured product. Depending on the application, the processing method, the type, and amount of reinforcing material as well as the hardener component are selected individually. Typically, crosslinking, based on free-radical induced polymerization mechanism, takes place at room temperature.

Resin base


Standard resin with a good mechanical resistance, short curing times, but a relatively low chemical resistance.


Highest chemical and hydrolysis resistance, high heat deflection temperature, and very high mechanical stability.


Very high mechanical stability as well as a very high resistance to hydrolysis, chemicals and UV irradiation.


Higher grade resin with high strength parameters and a high resistance to hydrolysis and chemicals.

In addition, there are variants with special property profiles.



With Gremolith AG’s unsaturated polyester resins, combined with suitable reinforcing materials and a suitable processing method, you will succeed in creating product solutions tailored to the respective applications.

  • As laminating, spraying, pressing, winding and injection resins for all types of glass-fiber-reinforced plastic parts.

  • Surface resins as gel coats or top coats for the protection and color design of plastic parts.

  • As casting resins for the button and jewelry industry and for polymer concrete production.

  • Additive products such as hardeners (peroxides), accelerators, inhibitors, release agents and color pastes.

Additional products

Gremolith AG offers all manufacturers of fiber-reinforced plastic parts all necessary additional products, such as gelcoats, topcoats, hardeners, accelerators, release agents, as well as a comprehensive program for the production of GRP molds.


Special modifications and formulations of Gremolith AG's unsaturated polyester resins offer you solutions for fire- and flame-retardant systems that meet the relevant standards for rail vehicles, commercial vehicles, tanks, pipes, ship and boat building, and in the construction industry.

  • EN45545-2

  • DIN EN ISO 5659-2

  • ISO 5658-2

  • ISO 5660

  • EN 13501

  • BS 467

Compared to unsaturated polyester resins, vinyl ester resins offer a particularly high chemical and thermal resistance. Typically dissolved in styrene, they react under the same conditions to form high-strength, thermoset plastics.

  • Copolymer made/composed of epoxy resin with/and monocarboxylic acids.

  • Exceptional chemical stability against acids, alkalis, and a wide range of other chemicals​​​​​​​.

  • High thermal resistance with good mechanical properties.

  • Application in corrosive environments, e.g. in chemical process plants or other industries with similar requirements.

This special variant of unsaturated polyester resins are formulated without styrene and can be applied wherever styrene is to be avoided from a physiological or occupational hygiene perspective.

Polyurethane and epoxy casting resins

The wide range of casting resins based on polyurethane and epoxy resins offers you a variety of possible applications in model and mold making. Depending on the casting process you are aiming for, whether solid casting, backfilling or front-layer casting, you can choose between a series of suitable products.


  • Efficient and economical production of foam, RIM and vacuum thermoforming molds.

  • For models, core souls and negatives.

  • Customized to the respective casting processes.

  • Casting of components for motors and insulators in the electrical industry.

Furan and phenolic resins

With over 30 years of experience, at Gremolith AG we develop and produce special furan and phenolic resins. We guarantee the highest quality standards throughout all production steps.

Phenolic resins are synthesized as polycondensate of phenol with formaldehyde.

Furan resins are copolymers of furfuryl alcohol, urea, phenol, etc.


  • Applications in adhesives, impregnations, electrical insulations, coatings and composites.
  • Exceptional heat and fire-resistant properties​​​​​​​​​​​​​​.
  • Binder for sand casting molds.


Production of laminates, coatings, and moldings compounds with acid-curing aqueous phenolic resins.

  • Railway applications – Fire protection in rail vehicles according to EN45545-2: HL3
  • Flame-retardant and combustible
  • Very hard plastics or plastic films
  • Excellent temperature and chemical resistance
  • Very good dimensional stability
  • Very low water absorption/uptake

Furan resins are becoming increasingly important from an ecological point of view, since the starting materials can be generated from food production residues. Free of fossil raw materials, this strategy enables us to produce thermoset, fiber-reinforced plastics, composites, or natural fiber-reinforced semi-finished products.