二羟甲基脲制备的GUF树脂胶黏剂的结构与性能

Structure and Properties of GUF Resin Adhesive Prepared from Dimethylol Urea

为从源头上降低木材胶黏剂中的甲醛含量,减小胶合板释放的甲醛对环境和人体造成的危害,采用无毒的乙二醛(G)取代甲醛,与二羟甲基脲(DMU)反应,合成乙二醛-尿素-甲醛(GUF)共缩聚树脂。通过红外光谱(FT-IR)对树脂的结构机理进行了表征,并测定树脂的理化性能,以探讨一种优化GUF胶黏剂的合成工艺。结果表明,原料物质的量比对树脂的固含量和黏度均有较大影响,高n(DMU)/n(G)会导致树脂的黏度大幅提高;树脂对杨木单板具有良好的润湿性,不同GUF树脂胶合板的干状胶合强度和冷水浸泡24 h后的强度均大于0.70 MPa,但胶合板会释放一定量的甲醛,且甲醛释放量会随着n(DMU)/n(G)的增加而增加。综合考虑,n(DMU)/n(G)在1~1.2的范围比较合适。

In order to diminish the formaldehyde content in wood adhesives from the source,and decrease fundamentally the harm of formaldehyde emission from wood panels to environment and human health,in this paper,glyoxal(G)was chosen to react with dimethylol urea(DMU)to prepare glyoxal-urea-formaldehyde(GUF)co-condensed resin with different molar ratios.The structural mechanism of Fourier infrared spectroscopy(FT-IR)was studied by measuring and chemistry to optimize GUF adhesive synthesis process.These results showed that the molar ratio plays important role in the solid content and viscosity of GUF resin.The high molar ratio causes a great increase in the viscosity of the resin.The resin on poplar veneer is good of wettability.Both the dry and wet bonding strength of plywood bonded with different DMU/G molar ratio GUF resins are higher than 0.70 MPa,but the formaldehyde emission of the plywood increases with the molar ratio of DMU/G.Considering the physical and chemical properties of GUF resin and formaldehyde emission,the proper molar ratio of DMU/G was in the range of 1.0∶1.0-1.2∶1.0.