What Does Urea Resin (UF) Mean?
A urea resin is a type of synthetic resin created from the condensation of urea and formaldehyde to form a polymeric molecule. As such, it is often referred to as urea-formaldehyde (UF) or urea-methanal. Urea ((NH2)2C=O) and formaldehyde (H2C=O) form polymeric structures with the form:
H[NHC=ONHCH2]nOH, or H[NHC=ONHCH2OCH2]nNHC=ONHCH2OH
when synthesized in acidic or alkaline conditions, respectively.
The advantages of UF resins include fast cure times, high strength and cost effectiveness. Disadvantages include sensitivity to moisture and toxicity from slowly released formaldehyde. UF resins are primarily used in interior wood adhesion, but are also used in decorative laminates, controlled-release nitrogen fertilizers and foam insulation.
Corrosionpedia Explains Urea Resin (UF)
Formulations of urea resins have desirable physical properties, including:
- High tensile strength
- High surface hardness
- High flexibility
- High heat distortion temperature
- Fast cure speed
- Low water absorption
- Low moisture resistance
- Consistent volume
Urea resins have a refractive index of 1.55. Cure times may be lower than 2 seconds under elevated temperatures.
The breakdown of urea resins releases formaldehyde gas, which causes health issues when the concentration is above 1.0 ppm. Above 3.0-5.0 ppm, respiratory irritation, coughing, burning sensations, rashes and increased risk of cancer development can occur.
Due to the health dangers, urea resin based foams are no longer used for insulation, despite their convenient application procedures. Commercial companies have developed low-formaldehyde emitting urea resin formulations.
Urea resins work well as adhesives in the wood industry to connect wooden and particleboards. It is also used in coatings. Movie production crews have used urea foam as artificial snow.