FARVESTABILISEREDE PHENOLHARPIKSSKUMSTOFFER SAMT FREMGANGSMAADE TIL FREMSTILLING DERAF
The present invention relates to foams made of resol-type phenolic resins which do not discolor as quickly as prior-art phenolic foams. With the additive in accordance with the invention, even colored foams will not darken as readily. The foams in accordance with the invention contain as stabilizers...
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Zusammenfassung: | The present invention relates to foams made of resol-type phenolic resins which do not discolor as quickly as prior-art phenolic foams. With the additive in accordance with the invention, even colored foams will not darken as readily. The foams in accordance with the invention contain as stabilizers salts of phosphinic acid or phosphonic acid, such as the primary alkali phosphites or the alkali phosphinates. The stabilizers, which protect the foams against the action of light and/or air and/or heat, are used in amounts ranging from 0.1 to 5 weight percent. The present invention further relates to methods of preparing such foams. In a preferred method, the stabilizers are admixed with an expandable resol-type phenolic resin, the mixture so obtained is mixed with the other substances necessary to formation of a foam, and the whole mixture is then foamed conventionally. |
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