The Low Toxicity Of Urea-formaldehyde Resin Synthesis Reaction Kinetic Studies

Urea formaldehyde resin has many advantages such as abundant raw materials, low cost, good agglutinative performance and so on. So it is used for wood adhesive widely. However, it has some disadvantages: large shrinkage in solidified process, causing crevice of rubber layer easily, especially slowly emitting of toxic substances (for example formaldehyde, methyl alcohol) in the use process which seriously affect healthy in mind and body of people. Therefore, the researches on the synthetic technique, reactive dynamics and toxicity of urea formaldehyde have the extremely practical significance.Through consulting massive correlative literatures, the certain understandings on the research and current situations of production and usage of UF resin in domestic and abroad, have been got comprehensively analyzed and summarized. In view of existence insufficiency of UF resin, this article is mainly to research comprehensively on the synthetic reaction dynamics and toxicity of UF resin on the basis of predecessor's studies. The main content of this article was divided into following four parts:1 The optimum seeking of synthetic technique of low formaldehyde UF resin. The main synthetic technique parameters that influence on the performances of UF resin were researched through experiments. The experimental results indicate that: (1) with the decreasing of the molar ratio of formaldehyde and urea, the viscosity and solid-content of UF resin increase, but the content of hydroxyl and free formaldehyde in the resin decrease. The optimum molar ratio of formaldehyde and urea has been chosen at 1.2:1 through experiments. (2) In the resin polycondensation process, pH of reactive system increasing, on the one hand, can cause the content of hydroxyl in the resin gradually to increase and to prolong storage time of resin, on the other hand, can cause the viscosity of resin to reduce. In order to satisfy the need of actual production,...