三聚氰胺-甲醛树脂鞣剂粒径变化对鞣革性能的影响

Effect of particle size variation of melamine-formaldehyde resin tanning agent on tanning properties

以三聚氰胺和甲醛为原料,研究了其在水中反应时p H、摩尔比、温度和反应时间等因素对三聚氰胺-甲醛(MF)树脂粒径的影响,并以此为基础探究了三聚氰胺和甲醛在明胶与皮胶原纤维中原位反应生成鞣剂的粒径对明胶热稳定性及鞣革湿热稳定性的影响。试验表明,树脂鞣剂的粒径随着缩聚p H值的降低、摩尔比的增大,温度的升高和缩聚时间的延长而增大。当甲醛与三聚氰胺的摩尔比为3∶1,温度45℃,p H值为8.5,羟甲基化反应3h时树脂粒径小,利于其向皮纤维中渗透。完全渗透后控制缩聚p H值在4.5,缩聚反应2h时粒径较大,有利于鞣剂粒子与胶原纤维上的活性基团结合,进而提高皮胶原的湿热稳定性。

With melamine and formaldehyde as raw materials, the effects of various parameters including pH, molar ratio, temperature and reaction time on the particle size of melamine-formaldehyde （MF） resins in water phase were investigated. Under the guidance of the results, the influence of particle size of MF resins on the thermal stability of gelatin and the hydrothermal stability of tanned leather based on in-situ tannage were further studied. The results show that the particle size of MF resins increases with the decreasing of pH value, the increasing of molar ratio and temperature, and the extending of ployensation time. It＇ s beneficial for small particle size of MF resins to penetrate into the collagen fiber when molar ratio of formaldehyde to melamine is 3 ： 1, temperature is 45℃, pH value is 8.5 and methylolation reaction time is 3h. After fully penetration of pre-polymer, when the polycondensation pH value of 4.5 and condensation time 2h, the larger size of MF particles will be obtained. It is beneficial to combination of tanning agent particles and the active groups of collagen, thus improving the hydrothermal stability of collagens.