Practical modification of urea-formaldehyde pre-taped
Plywood is made adhesives, leather and skinned sandwich made of three parts. According to local production status, mainly from my office close correlation between penetration and glue on from the above three parts to be analyzed separately.
First, the pre-urea-formaldehyde adhesives generally adhesive. Because the vast majority of small and medium sized local production, inevitably a lot of presence, such as solid Content is low, small viscosity, low bonding strength and higher formaldehyde problems. In particular, green plastic, in order to reduce formaldehyde emissions, it will cause serious problems, such as poor stability, tack too, preloading time is too long and strong glue Too low and so on. Due to pre-urea-formaldehyde adhesive itself is easy to penetrate solid content coupled with low, low viscosity, small initial tack and isometric preload time, its easier to penetrate, especially the most vulnerable green plastic penetration, local plywood factory in under-standing, not Debu increase the amount of flour used, and the corresponding increase of the amount of glue, glue too much to resist penetration to ensure plywood preload and bonding strength. As the heat from urea-formaldehyde adhesive, generally used for preloading have no backing plate, the most important Rather than only without preload bonding strength, its penetration time is very short, very little penetration, can in a certain amount of ammonium chloride, subjected to hot press rapid film formation, and significant province surface glue saving (i.e. glue dilute , glue less), it makes no difference A few pre-urea-formaldehyde adhesive catch, worth considering. In fact, in contrast, we can launch a pre-pre-press of the urea-formaldehyde adhesive, and to have the backing of the board without preload influence is particularly important, only the more easy to achieve pre-press, the more easily Film, its penetration shorter the time, the less permeable to the closer urea-formaldehyde adhesive heat, the more easily achieve their province province glue surface.