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US 5,674,971 AGranted
Urea-formaldehyde resin composition and method of preparation thereof
AssigneeGeorgia-Pacific Resins, Inc.
InventorLarry R. Graves
Life of this patent
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Abstract
A urea-formaldehyde resin useful as a binder for making a variety of products, and a method for making the resin. The resin is prepared by reacting formaldehyde, urea, and ammonia in at least a two under alkaline conditions and optionally neutralizing the resin in a third step. The urea-formaldehyde resin thus produced has good resistance to hydrolysis, cures quickly, and is characterized by low formaldehyde emissions (release).
Claims28
A method of preparing a urea-formaldehyde resin comprising
- mixing formaldehyde (F), urea (U), and ammonia and heating the mixture at an alkaline pH to an elevated temperature for a time sufficient to form a cyclic triazone/triazine polymer, the reactants being present in amounts to provide an initial F/U mole ratio between about 1.2:1 and 1.8:1 and an ammonia to urea mole ratio between about 0.05:1 and 1.2:1;
- adding additional formaldehyde to the mixture to yield a cumulative F/U mole ratio of between about 1.5:1 and 3.0:1, adding an acid to lower the pH, and reacting for a time sufficient produce the urea-formaldehyde resin.
A urea-formaldehyde resin prepared by a method comprising:
- mixing formaldehyde (F), urea (U), and ammonia and heating the mixture at an alkaline pH to an elevated temperature for a time sufficient to form a cyclic triazone/triazine polymer, the reactants being present in amounts to provide an initial F/U mole ratio of between about 1.2:1 and 1.8:1 and an ammonia to urea mole ratio of between about 0.05:1 and 1.2:1;
- adding additional formaldehyde to yield a cumulative F/U mole ratio of between about 1.5:1 and 3.0:1, adding an acid to lower the pH, and reacting for a time sufficient produce the urea-formaldehyde resin.
Dependencies are inferred from the claim text.