Low Pressure 2K SPF Kits

UNIQUE CHALLENGES RELATED TO BLOWING AGENT ADAPTATIONS

JUNE 6, 2014

CPI LOW PRESSURE WORKGROUP
Foam kit technology

Applications

Importance of shelf life

Chemistry considerations

Summary 

Conclusion

Outline
The Next Two Slides Graphically 

Illustrate Basic 2 Component 

Low Pressure (LP) SPF Kit 

Technology

DEFINITION OF A “LOW PRESSURE 2 COMPONENT SPF KIT” 

Spray polyurethane foam (SPF) products that are pressurized to

< 250 psi during manufacture and are sold in pressurized 

containers as two parts or components (2K) (A side & B side), also 

referred to as 2K-LP Kits.
2K Low Pressure SPF Foam Kits

isocyanate

• 134a

• A-component

polyol blend • B-component

A

B

• 134a

Blowing agent must be partially 

soluble in the liquid A 

& B side components

Blowing agent is the

sole propellant. Also

maintains proper A/B

ratio. 

150-200 psi
2K Low Pressure SPF Foam Kits

polymer

After mixing the polyol blend and 

isocyanate, polymerization begins in the 

gun nozzle with the blowing agent acting 

as the propellant and foaming agent

A & B must be

on ratio

Mixing Nozzle
Typical Applications of 2K LP Kits

◦ Used for air sealing and insulation in commercial and residential construction 

(next slide..)

◦ Portability of kits enables their use on difficult-to-reach jobsites

◦ High rise commercial construction

◦ In-field pipeline insulation in gas and oil transport

◦ Small, tight spaces, i.e. roof/wall junctures in commercial building renovation

◦ Also used in other industries such as mining and transportation (cold storage) 

6
Typical Energy-Saving Application Areas for 2K Low Pressure SPF Kits
Special Area of Concern: Shelf Life 

2K Low Pressure SPF is sold through distribution 

The kits must have at least one year shelf life because:

◦ They are transported to distribution centers and outlets across 

the US & Globally

◦ They remain in distribution channels for 1 – 6 months

◦ Contractors often use kits 1 – 6 months after purchase

◦ Contractors leave them on jobsites for extended periods before 

use

Kits can be exposed to elevated temperatures (> 80F) during 

transportation, storage or end-use in hot climates
Low GWP blowing agents are designed to break apart in the atmosphere

◦ The only known alternative blowing agent, Solstice GBA (aka 1234ze, trans 1,3,3,3-

tetrafluoropropene), contains a carbon-carbon double bond 

◦ The carbon double bond is the site of attack for UV radiation, which ultimately leads to a low 

GWP

This carbon double bond is particularly susceptible to attack by the tertiary 

amines used to catalyze SPF 

Breakdown of the blowing agent within the packaged product creates chain 

reactions, resulting in poor shelf life

Chemistry Considerations Regarding 

Alternative Blowing Agents 
Solstice GBA, aka 1234ze

carbon-carbon

double bond
Continued..

In 2K low pressure SPF products, temperature & pressure combine to accelerate

chemical reactions within the foam cylinders

◦ Low pressure SPF products are pressurized to 150 – 200 psi during manufacture

◦ This pressure forces the molecules in the B-side blend to “interact” with each other more 

quickly than at atmospheric pressure (i.e. in drums that are not pressurized until use)

◦ Strongly basic tertiary amines are utilized in all forms of SPF to catalyze foam’s A/B reaction

◦ These amines are strong enough to affect Solstice GBA’s carbon-carbon double bond, 

especially under pressure

◦ Results in unpredictable B-side chemical reactions
Results of Shelf Life Testing

The inherent pressure contained within the 2K LP products, coupled with 

exposure of the kits to excessive heat during transportation, storage, and use, 

can create a mild “pressure cooker” environment, which potentially leads to 

unwanted chemical reactions 

134a is a very stable molecule under these conditions

To date, low pressure manufacturers are observing shelf lives much less than 

one year 

◦ Replacing 134a with Solstice GBA in current formulations results in approx. 2 – 8 week shelf 

life in standard manufacturer testing*

◦ Solstice GBA is NOT a drop-in solution

*manufacturers collective observations
Summary

Due to the unique nature of 2K low pressure SPF products, manufacturers will 

require a longer time frame than high pressure SPF suppliers when converting to 

alternatives. The only known alternative gaseous blowing agent for low pressure 

SPF products, 1234ze, presents serious challenges related to shelf life. The 

amount of R&D time needed to overcome this issue is unpredictable. In 

addition, low pressure SPF manufacturers also face the same challenges as High 

Pressure SPF with regards to product testing requirements and time frames.*

* May 20, 2014 presentation by CPI to EPA Snap Office
Conclusion 

Low pressure manufacturers will need to reformulate and test all formulations 

for shelf life stability – the known alternative is not a drop in, and appears to 

contribute to unwanted and irreversible reactions in the product

The current alternative gaseous blowing agent is unproven in any commercial 

application, and gives unacceptable results in low pressure manufacturer’s

testing

There is a need for additional blowing agent options

A zero GWP product solution can be achieved given the proper amount of time 

and suitable alternatives
CPI Low Pressure Work Group 

Convenience Products

Dow Products

Fomo Products, Inc.

RHH Foam Systems