METHOD OF MAKING PLYWOOD Russian patent published in 2024 - IPC B27D1/04 

FIELD: woodworking industry.

SUBSTANCE: adhesive is made by adding to dry nanocrystalline cellulose in amount of 2% of the total weight of the adhesive in amount of 12% to obtain a suspension, which with constant mechanical stirring for 10 minutes is gradually added to phenol-formaldehyde resin in amount of 86% or to carbamide-formaldehyde resin in amount of 85.2%, after which the formed mixture is treated with an ultrasonic field with oscillation frequency of 24 kHz for 3 minutes at room temperature. A hardener – ammonium chloride in amount of 0.8% is additionally added to the mixture with carbamide-formaldehyde resin after treatment with an ultrasonic field and mixed with it. After that, the obtained adhesive in amount of 155 g/m² is applied on both surfaces of the middle layer and the inner surfaces of the outer layers of the birch veneer and laid on top of each other, plywood is cold pressed under pressure of 1.1-1.5 MPa for 10-12 minutes and its hot pressing under pressure of 2 MPa at temperature of 115-120 °C for 8.3-10 minutes, holding plywood at room temperature and humidity 60% for 24 hours and its treatment with pulse magnetic field with intensity of 18⋅10⁴ A/m at room temperature for 1 min by series of symmetric unipolar pulses of triangular shape with duration of 10 mcs, repetition frequency of 100 Hz and amplitude of 0.3 T.

EFFECT: higher physical-mechanical and ecological properties of plywood.

1 cl, 1 tbl