What are blowing agents? | Ask Mason Knowles - SPF Consultant | Spray Foam Technical Questions and Answers | SprayFoam Magazine Q&A Forums

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dan pruglo Posted: Feb 04, 2011 11:25 PM	What are blowing agents? What exactly are blowing agents and how much blowing agent is put into a barrel of 2lb. Also can a blowing agent dissipate from polyol?
mason Posted: Feb 05, 2011 08:22 AM	Blowing agents are what causes a foam to be a foam instead of just a mass of solid material. In the sprayfoam world, blowing agents are either a chemically reactant type such as water or a physical type such as the hydrofluorocarbons (HFCs) The blowing agents are mixed in the B side of the material along with; catalyst to help control the speed of the reaction, surfactants which control the shape, size and physical properties of the foam cells and helps keep the other ingredients in solution, polyol resins which when mixed with the A side creates the solid material and fire retardants to minimize the flame spread and smoke developed in case of fire. Depending on the formula (1/2 lb, 2 lb, 3 lb density) the blowing agent makes up from 10 to 15% of the B side chemicals. The reactant type of blowing agent(water) chemically reacts with the A side of the foam causing it to create gas (carbon dioxide) that creates bubbles that form foam cells. A physical type blowing agent has a low boiling point that turns into a gas at fairly low temperatures. For example the blowing agent used in closed cell sprayfoam (HFC 245fa) has a boiling point of around 62 degrees F. When the B side is heated and mixed with the A side, it creates a gas that creates bubbles that form foam cells. Blowing agents such as HFC 245 fa can escape from the liquid blend in the B side if exposed to higher heat than recommended by the supplier. Like a hot Coke in a can, the blowing agent will create a pressure inside the drums and make them bulge. If enough blowing agent escapes from the liquid due to high temperatures, the foam would not rise as well and have a higher density than desired. So, it is important to maintain the temperature of the foam during storage and shipping (typically between 60 to 80 degrees F)
dan pruglo Posted: Feb 05, 2011 12:29 PM	so h20 is technically a blowing agent? i have some iso and poly that i mix works good but i also have some old poly that i mix with the good iso does not much becomes gooy, missing calayst or blowing agent? thanks mason great reply on blowing agents.

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Comments

dan pruglo

Posted: Feb 04, 2011 11:25 PM

What are blowing agents?

What exactly are blowing agents and how much blowing agent is put into a barrel of 2lb. Also can a blowing agent dissipate from polyol?

mason

Posted: Feb 05, 2011 08:22 AM

Blowing agents are what causes a foam to be a foam instead of just a mass of solid material.

In the sprayfoam world, blowing agents are either a chemically reactant type such as water or a physical type such as the hydrofluorocarbons (HFCs)

The blowing agents are mixed in the B side of the material along with; catalyst to help control the speed of the reaction, surfactants which control the shape, size and physical properties of the foam cells and helps keep the other ingredients in solution, polyol resins which when mixed with the A side creates the solid material and fire retardants to minimize the flame spread and smoke developed in case of fire.

Depending on the formula (1/2 lb, 2 lb, 3 lb density) the blowing agent makes up from 10 to 15% of the B side chemicals.

The reactant type of blowing agent(water) chemically reacts with the A side of the foam causing it to create gas (carbon dioxide) that creates bubbles that form foam cells.

A physical type blowing agent has a low boiling point that turns into a gas at fairly low temperatures. For example the blowing agent used in closed cell sprayfoam (HFC 245fa) has a boiling point of around 62 degrees F. When the B side is heated and mixed with the A side, it creates a gas that creates bubbles that form foam cells.

Blowing agents such as HFC 245 fa can escape from the liquid blend in the B side if exposed to higher heat than recommended by the supplier. Like a hot Coke in a can, the blowing agent will create a pressure inside the drums and make them bulge. If enough blowing agent escapes from the liquid due to high temperatures, the foam would not rise as well and have a higher density than desired. So, it is important to maintain the temperature of the foam during storage and shipping (typically between 60 to 80 degrees F)

dan pruglo

Posted: Feb 05, 2011 12:29 PM

so h20 is technically a blowing agent? i have some iso and poly that i mix works good but i also have some old poly that i mix with the good iso does not much becomes gooy, missing calayst or blowing agent?
thanks mason great reply on blowing agents.

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