Polyurethane: the closed-cell advantage.

Rigid foam has the following qualities making it suitable as insulation:

• Low thermal conductivity
• Low water absorption
• Excellent adhesion to a range of materials
• Thermal stability from −160 °C to 120 °C
• Flow properties suitable to fill any shape of cavity
• Good flame retardant performance

Building industry

• Sandwich panels and rigid slabs
• Pre-insulated pipes; moulded or cut half-pipe sectionals
• Spray foam
• Supports for lightweight concrete and prefabricated walls / slabs

Thermal insulation for the food industry

• Refrigerated showcases; domestic & commercial refrigerators and deep-freeze chests
• Fishing-vessel hulls & storage areas; ice boxes
• Refrigerated containers, trucks and transport

Hot / cold purposes

• Hot-water heater tanks
• Insulated drink & food containers
• Temperature-controlled rooms and vessels

Polyurethane is based on the polyaddition reaction between a polyol and a diisocyanate — an exothermic reaction. Polymerization is influenced by the type of polyol and isocyanate components as well as additives. Cell formation is obtained by adding a blowing agent (halogenated hydrocarbons with a low boiling point, or water, which reacts with isocyanate groups to form CO₂).

Density classes

Material class	Density	Typical uses
Solid PU elastomers	1,200 kg/m³	Print rollers, cast elastomers, RIM solid plastics
Microcellular foams & elastomers	800 kg/m³	Coatings, adhesives, sealants, elastomers
Low-density foams	from ~6 kg/m³	Footwear soles, integral-skin, bedding & upholstery, packaging
Rigid insulation foam (KPI)	30–55 kg/m³	Spray, panel and pour-in-place insulation

Thermal conductivity — rigid PU vs other insulation (equal performance thickness)

Insulation material	K-value W/m·°C	Thickness (mm)
Rigid polyurethane foam	0.019	34
Phenolic foam	0.037	42
Expanded polystyrene	0.040	48
Expanded cork	0.045	50
Fibre glass	0.045	40
Reinforced cement	0.050	90
Glass mineral wool	0.055	55
Foam glass	0.060	69

Thermal conductivity — rigid PU vs other insulation (equal performance thickness)

Insulation material	K-value W/m·°C	Thickness (mm)
Rigid polyurethane foam	0.019	34
Phenolic foam	0.037	42
Expanded polystyrene	0.040	48
Expanded cork	0.045	50
Fibre glass	0.045	40
Reinforced cement	0.050	90
Glass mineral wool	0.055	55
Foam glass	0.060	69

Product features (finished product)

• Form and dimensional stability · thermal conductivity · density
• Compressive strength, tensile strength, impact resistance
• Cell structure — open/closed cell content · burning properties
• E-modulus, flexibility and elongation · surface hardness
• Moisture-vapour and gas permeability

Process features (during processing)

• Good flowability · adjusted reactivity and curing
• Component and substrate temperature control
• Demoulding time and demouldability
• Easily sprayable, low aerosol formation · miscibility
• Wide processing tolerance

Environment — waste sources within KPI are carefully monitored under the environmental care system; waste is separately stored and removed, with a dedicated controlled storage area for chemical waste. Our production and formulations aim for the least possible environmental consequences.

Grade	Mix ratio (polyol:MDI)	Applied density kg/m³	Remarks
SS 30 / 35 / 40	100:100	30–42	HCFC spray systems, good insulation & dimensional properties · DIN 4102-1 B3
SS 40F2	100:100	40–42	HCFC spray · DIN 4102-1 B2
PS 40 / 45 / 70	100:115–120	40–46	Discontinuous panel; also cavity filling & hand-mix insulation · B3
PS 44F2	100:125	44–46	Fire doors — up to 20-minute fire rating
PS 70F2	100:115	40–42	Discontinuous panel with 141b · DIN 4102-1 B2
PS 40NP	100:7.5 (n-pentane):142	42–45	n-pentane system for discontinuous panel production
PS 30	100:115	40–42	Polystyrene-bead adhesive by spray, construction
RS 40	100:130	~40	Refrigeration systems
WH / PS 20	—	—	Water-heater insulation grades
AS 100	100:150	40–42	Water-based PU adhesive for styrene-board panels (continuous)
HD 500	100:100	150–160	High-density PU for wood imitation
BS 40	100:100	40–42	Pour-in-place grade

TDS & MSDS sheets for every grade are available from our technical team on request.

To achieve the best results from these systems, good spraying practices must be followed:

• Substrate preparation — surfaces must be free of oil, grease, waxes, rust scale, loose dirt and water. Some metal surfaces need sandblasting and priming for adequate adhesion.
• Substrate temperature — has a major effect on foam density and adhesion; cold-weather spraying requires compromises.
• Machine setup — accurate ratio, temperature and pressure (see our GRACO Reactor line) protect the specified insulation value.