Catalysts Play a Key Role in the Production of Polyurethane Foams by Controlling Polymerization and Expansion Reactions
Why Are Catalysts Important?
In addition to altering the speed of these reactions, catalysts significantly influence the final physical properties of the foam.
Even though catalysts are used in small quantities in formulations, selecting the right one is critical to maintaining the quality of the final foam. A proper choice prevents issues like cracks, scorching (yellowing), excessive shrinkage, and material losses.
Depending on the production process, three types of catalysts need to be defined:
- Polymerization Catalyst
- Expansion Catalyst
- Balanced Catalyst (Polymerization/Expansion)
In all cases, delayed-action (blocked) catalysts can be used if necessary. These help simplify the process and aid in eliminating air bubbles. A perfect combination of amine and organometallic catalysts is also essential for balanced reactions. This combination ensures foams with greater air permeability, higher resilience, and low permanent deformation.
Types of Catalysts
Amine Catalysts
Polymerization/Gelling Catalysts
- Promote the reaction between polyol and isocyanate.
Often sufficient to produce conventional polyurethane foam, but expansion catalysts are usually required for most formulations
Expansion Catalysts
Facilitate the reaction between water and isocyanate, generating gases that expand the foam.
Balanced Catalysts
- Combine polymerization and expansion reactions to ensure foam quality.
- Prevent premature polymerization, which could trap gases and cause side cracks in blocks
Blocked Catalysts
- Delay the start of reactions (cream time) without significantly affecting the final growth time.
- These can be applied to polymerization, expansion, or balanced catalysts.
Organometallic Catalysts
Organometallic catalysts, such as tin octoate, are essential for flexible polyurethane foam production. They accelerate the “isocyanate-hydroxyl” polymerization reaction (commonly known as the gelling reaction).
Storage
- Keep in sealed containers in a dry place.
- Once opened, use promptly (solutions diluted in polyol should be used the same day).
Why Not Use Just One Type of Catalyst?
The type and concentration of the catalyst depend on the desired foam characteristics and specific production conditions, such as:
- Ambient temperature
- Mold temperature
- Formulation complexity
- Skin formation
- Curing and demolding times
- Block height
Understanding these factors ensures the selection of the most suitable catalyst, guaranteeing superior foam quality.
Technology for Flexible Foams
Amino provides a complete line of solutions for Flexible Polyurethane Foams.
Our portfolio includes silicones, amines, pigments, additives, binders, and ready-to-use systems. With a technical team of polyurethane experts, we guide customers toward the best solutions, combining high-quality raw materials with process efficiency.
Amino Solutions for Flexible Foams
Performance Additives
- Silicone surfactants
- Amine catalysts for expansion and gelling
- Delayed-action catalysts
- Low-VOC catalysts
- Tin octoate
- Liquid and paste pigments
- Adhesion promoter additives (flame bonding)
- Cell-opening additives
- Additives for elongation and tear resistance
- Hardness additives
- Anti-scorching additives
- Halogenated and non-halogenated flame retardants
Ready-to-Use Flexible Systems
- Viscoelastic systems for block processes (all MDI-based)
- Viscoelastic systems for block processes (TDI-based)
- Viscoelastic systems for molded processes (MDI-based)
- Hyper-soft systems for block processes (TDI-based)
- Hyper-soft systems for molded processes (MDI-based)
- Flexible HR systems for block processes (MDI-based and TDI-based)
- Flexible HR systems for molded processes (MDI-based and TDI-based)
Complementary Products for Flexible Foams
- Binder adhesives
- Adhesives for foam-to-fiber bonding (sponges)
- Gel pads
For more information about Amino Technology, contact us at +55 11 4077-3777 or email us at vendas@amino.com.br.
