| 摘要 |
A process for producing stable urea-aldehyde polymers with high structural strength from two storable liquid ingredients. In this process, partially cured liquid urea-formaldehyde resin is reacted with an aqueous cross-linking solution comprising one or more alkyl or aryl dialdehydes containing two to eight molecular carbons and the hydrogen ion concentration needed to catalyze the completion of the reaction of the dialdehydes and the urea-formaldehyde. The process for producing urea-aldehyde polymers, having improved structural strength and reduced aldehyde vapor emission during their production and prolonged use, is especially effective for manufacturing products for the building industry, such as urea-aldehyde insulating foam, wood-filled particle board, and plywood. The increased polymer strength and the elimination of the hazardous and objectionable aldehyde odor is achieved by maintaining the molecular ratio of total aldehyde moieties to urea to about 1.8 and the molecular ratio of the aldehyde moieties in the dialdehydes to those in formaldehyde at about 0.2. The process requires that the dialdehydes be substantially contained in the cross-linking solution for system storability and long term reactivity. The hydrogen ion concentration required in the cross-linking solution is represented by a pH of about 3 and may be achieved by addition of water soluble acid or by heating the mixture and converting some aldehydes to acids.
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