Environment-protective urea-formaldehyde resin with novel structure as well as preparation method and application thereof

The invention discloses an environment-protective urea-formaldehyde resin with novel structure as well as a preparation method and an application thereof. The environment-protective urea-formaldehyde resin with novel structure is prepared from formaldehyde, carbamide, performed polymer of the carbamide and dialdehyde and one or more modifying agents according to the process steps of weak base, weak acid and weak base. In the method, the performed polymer of the carbamide and dialdehyde is introduced in the reaction of matrix resin to prepare resin and generate stable alkyl ether structure (-CH2n-O-CH2n-) so as to reduce the content of methylene ether link in the resin, and meanwhile, the introduction of polyfunctional radicals enhances the degree of crosslinking of the resin, therefore, on the premise of ensuring the cementation strength and the water resistance of the resin, the formaldehyde emission of sheet materials in use is greatly reduced. The urea-formaldehyde resin prepared by the method has the advantages of low free formaldehyde content, low cost, simple process and favorable cementation strength. The formaldehyde emission of sheet materials manufactured by the sizing agent reaches the standard of E0 grade.