Study On The Adhesive Properties And Application Of Moisture Curing Isocyanate Adhesive (YQJ-S)

In this paper technological conditions were studies on bonding veneers with one — component moisture curing isocyanate (YQJ—S) adhesive at high moisture content (MC). The effects of MC, resin consumption, pressure, pressing time and preserving time on the adhesive properties were discussed in detail. It showed that the MC of veneers and resin consumption were remarkable factors; and the veneers, with MC up to 100%, could be successfully glued with YQJ —S adhesive. To get the same bonding strength, the resin consumption was just 1/2 to 1/3 out of that of traditional adhesives.Producing top—grade decoration veneer from fast—grown and small—diameter logs is an effective method to solve the shortage problem of the large diameter precious wood. It is also an important way to increase the added value of small—diameter logs. The YQJ—S adhesive can produce laminwood by veneer with high MC. And manufacturing slice veneers by laminwood can simplify the manufacturing process, reduce the cost. Moreover, the products are high — grade ornaments with the property of environmental protection, weathering resistance. Consequently man-made veneers and laminated veneers are made based on the optimized processes. The performance evaluateon indicated that the final products laminated wood and veneers met the demands, especially water resistance, thermal resistance were superior to these made by the traditional adhesive.The reaction tendency of YQJ — S adhesive and wood with high MC was evaluated by DSC (differential scanning calorimetry). Under the condition of the same MC of wood powder, the initial temperature and peak temperature of reaction of birch—wood powder with YQJ—S adhesive increased with high heating rate. The peak temperature of the wood powder with higher MC was smaller with the same heating rate. These indicated that YQJ—S adhesive and birch wood powder with high MC can react at room temperature sufficiently. The higher is the MC, the more sufficient is the reaction of YQJ—S adhesive with wood powder.By comparing the reactions of manchurian ash or birch wood powder with YQJ—S adhesive respectively, it appeared that, under the condition, the reaction of manchurian ash with YQJ—S adhesive is faster than that of birch with YQJ—S adhesive. It maight be caused by that manchurian ash is ring—porous wood, but birch is diffuse—porous wood, which resulted that the water was diffused quicker in manchurian ash than that in birch under the condition of high MC and heatring rate. Consequently, the reaction of manchurian ash with YQJ —S adhesive can be occurred at the very low temperature and the reaction come to be the maximum quickly. It indicated that the required activated energy was required for the reaction of YQJ—S adhesive with birch wood powder with high MC.