Method for whole-process alkaline synthesis of urea resin wood adhesive

Abstract

The invention belongs to the technical field of artificial board production and in particular discloses a method for whole-process alkaline synthesis of a urea resin wood adhesive. In the synthesis process, a composite alkali catalyst is used, the whole synthesis process is implemented under an alkaline condition, and formaldehyde and urea are added for multiple times, specifically, the method comprises the following steps: firstly, adding a formaldehyde solution into a reaction kettle to react with primary urea in different batches, and secondly, adding secondary urea into the reaction kettleto implement reactions in different batches. The urea resin wood adhesive synthesized by using the method has structure performance similar to that of a urea resin synthesized by using an alkali-acid-alkali process, the problem that a primary polymer generated at an alkali reaction stage in the alkali-acid-alkali process can be partially rearranged as a methylene bridge bond at the alkali reaction stage can be solved, and the content of an ether bond in the urea resin can be reduced. By adopting the method, the industry knowledge that a urea resin cannot be synthesized by using an alkali onlyis contradicted, and the blank of synthesizing the urea resin by using the alkali only is made up.

Description

technical field

[0001] The invention belongs to the technical field of wood-based panel production, in particular to a method for preparing a whole-process alkaline synthetic urea-formaldehyde resin wood adhesive. Background technique

[0002] Urea-formaldehyde resin is the most important basic adhesive in the production of wood-based panels, which has significant advantages such as fast curing speed and low manufacturing cost.

[0003] At present, the synthesis process of urea-formaldehyde resin is mainly a three-stage synthesis process of weak base-weak acid-weak base. The formaldehyde-urea molar ratio (F / U) of the process in the first alkaline reaction stage is generally controlled above 2 / 1, and the final molar ratio is reduced by adding the second urea in the final alkaline reaction stage, while achieving the reduction of free The purpose of formaldehyde content. The traditional theory holds that methylolation reaction mainly occurs in the initial alkaline reaction st...

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