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Views: 0 Author: Site Editor Publish Time: 2025-06-16 Origin: Site
Polyester polyols are commonly used in the production of polyurethane (PU) foams, including all-water-foamed systems where water acts as the sole blowing agent (reacting with isocyanate to generate CO₂ for foaming). Below are key considerations for using polyester polyols in water-blown PU foams:
Hydroxyl Value (OHV): Typically ranges from 30–300 mg KOH/g, depending on foam hardness and crosslinking needs.
Functionality (f): Usually 2–3 (for flexible foams) or higher (3–6) for rigid foams.
Acid Value: Should be low (<2 mg KOH/g) to avoid side reactions with isocyanates.
Molecular Weight: Lower MW for rigid foams, higher MW for flexible foams.
Better Mechanical Properties: Higher tensile strength, abrasion resistance, and durability compared to polyether polyols.
Thermal Stability: Superior heat resistance, making them suitable for high-temperature applications.
Hydrolytic Stability (if optimized): Some aliphatic or aromatic polyester polyols can be formulated for improved hydrolysis resistance.
Eco-Friendly: Water-blown foams avoid volatile organic compounds (VOCs) like CFCs or pentane.
| Challenge | Solution |
|---|---|
| High viscosity | Use low-viscosity polyols or blends with polyethers. |
| Hydrolytic instability | Select polyesters with hydrophobic backbones (e.g., aromatic or long-chain aliphatic). |
| Slow reactivity | Catalysts (e.g., amine or tin-based) can accelerate foaming. |
| Foam brittleness | Plasticizers or chain extenders (e.g., 1,4-butanediol) can improve flexibility. |
Flexible Foams: Automotive seating, shoe soles, mattresses.
Rigid Foams: Insulation panels, construction materials.
Coatings & Adhesives: Water-blown PU dispersions.
| Component | Function | Example |
|---|---|---|
| Polyester polyol | Base resin | OHV: 50–150, f=2–3 |
| Water (1–5%) | Blowing agent | Generates CO₂ |
| MDI/TDI | Isocyanate | NCO index: 90–110 |
| Amine catalyst | Reaction accelerator | Dabco 33LV |
| Silicone surfactant | Foam stabilizer | Tegostab B-8465 |
| Flame retardant (optional) | Safety | Phosphorus-based |
| Product Model | Hydroxyl value (mgKOH/g) | Acid Value (mgKOH/g) | Moisture (%) | Viscosity (CPS 25℃) |
| XF-2003 | 200±10 | ≤1.5 | ≤0.1 | 2000±500 |
| XF-2006 | 170±10 | ≤0.5 | ≤0.1 | 1500±500 |
