Processing Technology of High Solid Content Starch-Based Wood Adhesive

Abstract:

The high solid content starch-based wood adhesive was prepared by two-seed process. Firstly，the concentration effect of hydrochloric acid on viscosity of the high solid content starch-based wood adhesive was studied. Considering the degradation effect on shear strength，1.0 mol/L of hydrochloric acid was used. Then，two seed polymerization process was applied to further lower the viscosity of the system and improve the adhesive properties. Effects of the first/second seed ratio and the adding time of the second seed on storage stability of the high solid content starch-based wood adhesive were studied. It was shown that the adhesive showed the lowest viscosity and the best storage property with the first/second seed ratio of 8∶2 and the second seed being added after reacting for 2.5 h. Finally，the preparation was stable and less reflux with the conditions of 1% of APS(starch dry basis)，addition of 70% of the total APS at the beginning of reaction，10% of the total APS after adding the second seed and the rest 20% after taking out the second seed. The starch-based adhesive prepared by two-seed process possessed bimodal particle size distribution. The particles with different sizes reached the closest packing condition and more amount of emulsifier could be adsorbed on the surface of the small particles to restrain the starch retrogradation，which greatly improved the storage property of the high solid content of starch-based wood adhesive.