Polyurethane Foam 

Sealants

Tom Fishback

Fomo Products

February 15, 2012
2

Topics

• Foam sealants 101

• Types of products

• Applications & End Users

• PPE and labeling considerations 

• MDI exposure monitoring
3

Basic PU Chemistry

• Polyurethane is formed by the mixing and 

reaction of two components:

• “A Side” – diisocyanates

• “B Side – polyol blend

• With foam sealants, a third ingredient, the 

blowing agent, is added

• Low molecular weight hydrocarbon blowing agent used in 

consumer products
4

Manufacturing

•

• Flammable or non-flammable

•

• Blend of up to 10 ingredients

•

•

• MDI (reacts with water)

PROPELLANT

POLYOL

ISOCYANATE
5

Prepolymer Formation

• Solvent for the prepolymer

• Propellant for expelling prepolymer

 from the can 

•‘Blowing agent’ to build the cell 

 structure

PRE-POLYMER After mixing both components together,

polymerization begins with a conversion to 

a polyurethane prepolymer
6

PU One-Component Foam Terminology 

• OCF – One-component foam

• Most common term globally 

• Also known as IFS (insulating foam sealants)

• Tack-Free Time – skin formed on foam surface

• Typically 3 – 20 min.

• Cure Time – maximum foam physical properties 

achieved

• Typically 12 - 24 hours

– Determined through testing of ultimate physical properties, i.e. 

compression strength
7

OCF Sealants

• OCF sealants

• Isocyanate and Polyol combined in one container at 

time of manufacture

• Mixed at slightly greater than 1:1 into container

• Forms NCO-terminated PU in container

• 3-15% PMDI in container as marketed

• 3 – 10% DIY, 3 – 15% professional

• Reacts with ambient moisture

• R-NHCOOH + R - NCO ---> (R-NHCO)20 ---> 

R-NHCONH-R+ CO2
8

Types of Products

• OCF dispensed with 

plastic straw

– Professional & 

DIY

• OCF dispensed with 

professional gun

– Professional
9

Types of Products

• Cylinder OCF

• 10 – 20 lbs of 

chemical

• Dispensed with 

brass wand

• Professional 

product
10

Energy Efficiency

• Main usage for OCF in US: air sealing 

for energy efficiency.

• DOE states that up to 40% of heating 

and cooling energy is lost through air 

leakage in the building envelope

12

Global Market Size and Manufacturers

• > 250M cans annually

• Manufacturers

• N. America (3)

• Europe (>10)

• China (>10)
13

PPE Information

15

Typical Label Warnings


18

Worker Exposure Monitoring Case Study

• Species monitored: 

• MDI

• MDI & main oligomer (“3-ring”, n=1)

• Occupational Exposure Guidelines

• OSHA: 200 mg/m3 MDI (20 ppb; ceiling)

• ACGIH TLV®: 51 mg/m3 MDI (5 ppb; 8-h TWA)
19

MDI Monitoring Case Study

• In this study a cylinder foam product 

was used

– OCF cylinder foam contains 10 – 15% concentration of 

free MDI as opposed to 3 – 10% for OCF cans sold in DIY 

retail

– Foam bead dispensing times are typically longer for OCF 

cylinder products than for OCF cans purchased by 

consumers
20

Results From MDI Workplace Exposure 

Study: OCF Cylinder Foam 

Study 3,4,5: Lab Application 

• Adhesive, single use container; 11-24 min application

• Area samples at 1-20’, source ( 18”)

• Methods: Filter sampler (Study 3: IsoCheck; Studies 4,5: 13mm)

Sample Type MDI mg/m3

; Mean 

[range]

n* #ND

Personal -

Applicator

ND(6) [ND(1) –

ND(8)]

11 11

Area: Near (1-3’)

 Far (10-20’)

ND(1) 

[olig=ND(6)] 

ND(0.9) 

[olig=ND(5)]

1

1

1

1

Area: Source 9.2 [ND(6) – 51] 15 13

*n= # of samples; #ND = # of 

samples that were below 

limit of detection
21

Conclusion From Case Study

• Respirator use not necessary for typical 

OCF DIY application.
22

Questions?
APPENDIX 
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Sampler Types

– Coated Filter

– Impinger

– Impinger + filter

Exposure Monitoring
25

Iso Check Sampler

Exposure Monitoring