Refrigeration Insulation That Adapts To Blowing Agents
June 2005
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As U.S. government regulation of refrigeration appliances becomes stricter, BASF Corporation saw the need to create foam with good insulation value that meets the new regulations. The Elastopor insulation for refrigerator applications can adapt to different blowing agents, such as 141b, CP, and 245fa in order to help meet regulations that limit the use of CFCs and HCFCs.

The company focused a lot of its development work on the energy consumption of insulation and the new regulations surrounding blowing agents. To maximize the efficiency of the polyurethane that is injected into the cabinet, BASF started with old technology, learned from past processes, and came up with a new insulation. “BASF developed new polyols to adapt to gaseous type blowing agents,” explains Fernand Saad, technical representative for BASF Corporation. The new polyols trap HFCs more efficiently than the previous types.

The Elastopor insulation adapts to different blowing agents by using the proper resins, according to Mr. Saad. BASF can make different blends from two or three different chemicals that are compatible with the different blowing agents, he explains. Additives can also be added in order to make the insulation suitable for various blowing agents.

Creating this blend to be compatible with different blowing agents did prove to be a challenge. The company relied heavily on the resins, but the additives also proved to be a key part of the insulation. Two main groups of additives are in the formation. “One group actually controls the reaction, which is important in the foaming of a refrigerator. You want the foam to basically fill the cabinet and reactivity is one of the key elements,” explains Mr. Saad. “The other group helps to form the microcellular structure, which should preferably be small and spherical in shape to enhance the insulation factor.”

The company’s aim was to create small cells in regular shapes, which placed most of the development work on the additives.

Also, BASF does not make the additives, so it needed to test numerous additives to see if they were compatible with its resin products.

Elastopor also offers a lower K-factor. According to Mr. Saad, an insulation factor of less than 0.132 BTU in/ft2 h°F @ 75°F mean temperature would be an attractive level for the consumer refrigerator market, and Elastopor suffices this criteria by having a factor less than 0.130 BTU in/ft2h°F. “The cell size reduction was achieved by incorporating the most compatible surfactant, including the use of new polyols, collectively gave a synergic effect in lowering the K-factor (insulation value).”

According to the company, the foam’s curing time or de-mold time has been reduced by 15 percent, offering the possibility of increased production levels. It can also improve the reverse heat leakage of the foamed cabinet, produce a foam with less blow holes, and adapt to other blowing agents in other appliance applications such as water heaters.


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