The object of research - the technological process of manufacturing plywood. The aim - to develop the regimes for gluing the veneers for the manufacture of low-toxicity plywood on the basis of modified urea-formaldehyde adhesive compositions modified by wood fiber sludge. Research methods: physical, mechanical, chemical, drying-weighting, viscosimetric, potentiometric, flat pressing, perforating, statistical analysis. Scientific novelty: for the first time it was established that wood fiber sludge has an acidic nature, and the content of compounds in it differs from the chemical composition of wood. In particular, the content of holocellulose in the sludge is approximately 1,5 times smaller, and the content of lignin is 1,5 times greater, compared to their average content in the wood. It was first established that the addition of wood fiber sludge as a filler to a urea-formaldehyde adhesive composition reduces the concentration of ions of the Hydrogen and curing time, but increases the viscosity of adhesives, as well as makes it possible to obtain low-toxic adhesives with mass fractions of free formaldehyde 0.06-0.08% . The regresion dependences of the content of formaldehyde in the plywood and its shear strength from the parameters of the regime for gluing the veneers, in particular the amount of wood fiber sludge in the adhesive composition, the adhesive spread, the duration and the temperature of the pressing, were obtained. These dependencies allow setting the rational parameters of the regime for gluing the veneers and predict the content of formaldehyde in plywood and its shear strength from these parameters. Practical value: it was proposed and protected by the patent of the formulation of the adhesive composition based on urea-formaldehyde resin using wood fiber sludge as a filler, which provides low formaldehyde content in the adhesive composition, as well as the regimes for gluing the veneers that provide low levels of formaldehyde content in plywood and its normative indices of the shear strength. Recommendations for introducing adhesive formulations on plywood enterprises and the regimes for gluing the veneers based on adhesive compositions using wood fiber sludge for the production of plywood with reduced formaldehyde content have been developed. The corresponding implementation acts were compiled. The results of the research of developed adhesive compositions, modified with wood fiber sludge, and samples of plywood, made on their basis in the production conditions, confirmed the certainty of the conclusions of the dissertation. The economic effect is calculated and the feasibility of introducing into the production the research results, which will allow reducing the cost of glue and payment for formaldehyde emissions, because of their reduction due to the use of adhesive compositions with wood fiber sludge, and preventing environmental damage to the environment and especially to humans, is proven. The area - woodworking.
