含疏水结构分子对脲醛树脂胶调制黏度的控制

Effect of Molecules Containing Hydrophobic Groups on Viscosity of Urea Formaldehyde Resin

为减缓改性脲醛树脂与面粉调配后黏度快速升高对胶合板淋胶工艺施胶均匀性的影响,本研究提出利用含疏水结构分子的乙二醇油酸酯、三油酸甘油酯和吐温-80削弱调配胶液组分间缔合作用,控制胶液黏度,并探讨含疏水结构分子对胶液黏度及其变化速率以及胶合强度的影响。结果表明,非离子型表面活性剂类含疏水结构分子的吐温-80添加量为胶液质量的1.6%时,胶液黏度由4039mPa·s降低至3429mPa·s,且在调配后0.5~5.5h内,胶液黏度平均增加速率相比对照组降低74%。非离子型表面活性剂类含疏水结构分子的亲水端保障其在胶液体系中均匀分散,疏水端有效削弱胶液组分间缔合作用;适当添加非离子型表面活性剂类含疏水结构分子,可提高胶合板的胶合强度,但添加过量时,会降低胶合板的胶合强度。

The viscosity of the glue increased rapidly when the modified urea-formaldehyde resin combined with flour at the sprinkling process of manufacturing plywood.It significantly affects the uniformity of the adhesive layer.This study proposed a method to control the viscosity of the glue by diluting the association between the glue components with the molecules containing hydrophobic groups(ethylene glycol oleate,triolein,and Tween-80).The effects of the molecules containing hydrophobic groups on the viscosity and the change rate of the glue were discussed.Results show that when the amount of Tween-80 which was non-ionic surfactant was 1.6%of the glue mass,the viscosity of the glue decreased from 4039 mPa·s to 3429 mPa·s.Within 0.5~5.5 hours after mixing,the average increase rate of the glue viscosity reduced by 74%compared to the control group.The hydrophilic end of the molecules containing hydrophobic groups which were non-ionic surfactant ensures its uniform dispersion in the glue.The association between the components of the glue was effectively diluted by the hydrophobic end of the non-ionic surfactant.In addition,when the amount of non-ionic surfactant was appropriate,the bonding strength of the plywood prepared with the corresponding adhesive was higher than that of the control group.However,an excessive addition of the additive led to a decrease in the bonding strength of the plywood.