| 摘要 |
PURPOSE:The titled paste solution which does not lose its essential adhesiveness for a long time at room temperature and does not require washing, prepared by adding defatted soybean powder to a urea resin plywood adhesive containing free urea. CONSTITUTION:3-20pts.wt. defatted soybean powder is added to 100pts.wt. urea resin plywood adhesive containing 0.6-5wt% free urea. Conventionally, as a urea resin plywood adhesive, there has been used one which contains, in addition to a resin, flour as an extender, NH4Cl as a curing agent, etc. and, if necessary, water. When the excessive paste solution remaining after finishing the work and machines, apparatus, etc. to which the past solution is attached are left without any treatment, the attached paste solution, next day, will be dry or highly viscous and they will be brought to the state unsuitable for use. On the contrary, when the defatted doybean powder is added, the urea is decomposed by the action of urease cntained in the powder and forms ammonia. Accordingly, gelation or solidification of a paste solution can be controlled. On the other hand, during high-temperature compression for bonding plywood, the urease rapidly loses its activity and at the same time, the action of the curing agent is heightened and the resin performs its essential bonding by curing. |
