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| | Patent 6,150,489 |
 | | The diisocyanates which are preferably used are 1,6-hexamethylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, mixtures of diphenylmethane diisocyanate isomers with a 4,4'-diphenylmethane diisocyanate content of >96% by weight, and particularly 4,4'-diphenylmethane diisocyanate and 1,5-naphthylene diisocyanate. |
 | | The molar ratio of diisocyanates to polyols is preferably 1.2:1 to 30:1. |
 | | In the prepolymer method, an isocyanate-containing prepolymer is formed from the polyol and the diisocyanate, and this prepolymer is reacted with the chain extender in a second step. |
| www.pharmcast.com /Patents/November2000/112100OG/6150489_Polyurethanes112100.htm (2444 words) |
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