Hot Sale Spraying Rigid Foam Polyester Polyol NXF-400

For spray polyurethane foam (SPF), the polyester polyol you choose has a big impact on reactivity, adhesion, dimensional stability, and fire performance. 

What Spraying Foam Needs from a Polyester Polyol

Compared with slabstock or boardstock, spray foam requires polyols that provide:

• Fast but controllable reactivity (short cream & gel time)

• Good adhesion to concrete, metal, wood

• High crosslink density for rigidity

• Thermal and fire performance (especially PIR spray)

• Manageable viscosity for spray equipment

Recommended Polyester Polyol Types for Spray Foam

Aromatic Polyester Polyols (Most Common)

Best for:

• Closed-cell SPF

• Roofing spray foam

• PIR spray insulation

Typical properties

• OH value: 200–400 mg KOH/g

• Functionality: 2.5–3.5

• Viscosity: 1,500–5,000 cP @25 °C

Advantages

• Excellent rigidity

• Better fire performance than polyether polyols

• Strong adhesion

• Cost-effective

Modified Aromatic Polyester Polyols

Used when you need:

• Lower viscosity for easier spraying

• Better B-side compatibility

• Improved dimensional stability

Often blended with:

• Low-viscosity polyether polyols

• Reactive flame retardants

Polyester Polyol vs Polyether Polyol in SPF

Closed-cell SPF & PIR → Polyester polyol dominant
Open-cell SPF → Mostly polyether polyol

Typical Polyester Polyol Role in Spray Formulation

In a closed-cell spray foam B-side, polyester polyol usually makes up:

• 30–70% of total polyol blend

Blended with:

• Polyether polyol (processing & flexibility)

• Flame retardants

• Catalysts (amine + potassium for PIR)

• Surfactants

• Blowing agents (HFO / water)

 Prameters

Summary Recommendation

If your target is:

• Closed-cell SPF insulation → Aromatic polyester polyol (OH 220–260)

• PIR spray foam / roofing → Higher OH aromatic polyester polyol

• Easy spraying + balanced performance → Modified aromatic polyester polyol blend