Amines Play a Crucial Role in Polyurethane Manufacturing. Learn more about this essential raw material and explore AMINO’s comprehensive range of products.
Among the various chemical components used in the formulation of flexible polyurethane foams, amines—key catalysts for the reaction between isocyanates and water—are fundamental.
To produce foam, the polyurethane polymer is expanded by the introduction of gas bubbles. A convenient source of gas is carbon dioxide, generated from the reaction of an isocyanate group with water.
Figure I – Chemical reaction of amine and isocyanate generating CO2 for foam expansion
The intermediate product of this reaction is thermally unstable carbamic acid, which spontaneously decomposes into an amine and carbon dioxide. The diffusion of carbon dioxide into pre-nucleated bubbles in the reacting medium causes expansion, resulting in foam. Further reaction between the amine and additional isocyanate produces a disubstituted urea.
Amines are organic bases formed by replacing one, two, or three hydrogen atoms in ammonia (NH3) with carbon chains. Thus, the functional group of amines can be one of the three shown below:
Figure II – Functional groups of amines
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Classification of Amines
Based on the number of hydrogen atoms replaced, amines are classified as:
- Primary amines: 1 hydrogen replaced
- Secondary amines: 2 hydrogens replaced
- Tertiary amines: 3 hydrogens replaced
Tertiary amines are the most commonly used catalysts in the production of flexible polyurethane foams. These can be divided into four categories based on their effects on foam processability and final properties:
- Gelling or polymerization catalysts
- Blowing catalysts
- Delayed-action catalysts
- Skin curing catalysts
- Reactive catalysts
Table I – Types of tertiary amines
| CATALYST | CHARACTERISTICS/APPLICATION |
| N,N-dimethylethanolamine (DMEA) | Reactive blowing catalyst, low-cost liquid with minimal odor, used in flexible and rigid foams. |
| Diaminobicyclooctane (DABCO) or triethylenediamine (TEDA) | Gelling catalyst, water-soluble solid used in all types of polyurethane. |
| N,N-dimethylcyclohexylamine (DMCHA) | Low-cost liquid with strong odor, used in rigid foams, balancing gelling and blowing reactions. |
| bis-(2-dimethylaminoethyl) ether (BDMAEE) | Excellent blowing catalyst, low-odor liquid used in flexible block and molded foams. |
| bis-(2-dimethylaminoethyl) ether ethoxylated (BDMAEEE) | Reactive blowing amine for molded flexible foams. |
| 2-(2-dimethylaminoethoxy)-ethanol (DMAEE) | Reactive blowing amine for low-density flexible foams. |
| N-ethylmorpholine | Skin curing catalyst, volatile liquid with low viscosity used in molded flexible foams. |
| N,N,N’,N’,N’’-pentamethyldiethylenetriamine (PMDETA) | Blowing catalyst used in flexible, semi-rigid, and rigid foams, ensuring excellent flow at the start of the reaction. |
Reducing Odor in Foams
Some amines impart residual odor to the foam, limiting their use in applications like mattresses and upholstered furniture. Using more volatile amines can reduce odor but may also affect curing due to rapid catalyst loss. To address this, many catalyst suppliers have introduced amines with reactive isocyanate groups that bind to the polymer network, though this may reduce catalytic activity.
AMINO’s Comprehensive Amines Portfolio
AMINO offers a wide range of amines to meet diverse demands, including catalysts for gelling, polymerization, cream time control, solids (crystals), and blowing. Key products include AMICAT CMR 333, AMICAT CLR 312, AMICAT CRH 300, AMICAT AWS 337, and AMICAT CRH 351, among others. Technical datasheets are available to assist manufacturers in selecting the best amine for their applications.
Applications of Amino’s Amicat Line
- CLR 312, CRH 351, AWS 337, and CMR 333: Flexible foam (continuous process)
- CMR 333, AWS 337, and CMR 355: Flexible foam (discontinuous process)
- CLR 312, CMR 333, and AWS 337: Flexible foam (cylindrical block)
- CMR 333: Hypersoft foam (molded/block process)
- CLR 312 and CMR 333: High-resilience foam (block process)
- CLR 312, CMR 333, and CRH 351: High-resilience foam (molded process)
- CMR 333, CRH 351, CRH 315, and COM 388: Rigid foam (molded/block/spray process)
AMINO also provides technical expertise to recommend the most suitable catalysts for diverse polyurethane applications.
