Regulation of the specific consumption of resin over the surface of wood particles in the production of particle boards

The analysis of industrial microchips of the outer layers and chips of the inner layer of particle boards with a fine-structured surface is carried out. In the workshop, the selection of a fine fraction of wood particles and its withdrawal from the process flow is not carried out. The studied chips had the following rock composition: aspen – 60%, birch – 20%, pine – 20%. The absolute moisture content of the chips is 2%. The fractional composition of wood particles and their linear dimensions are determined. The specific surface area was calculated for each fraction and for the chip mixture as a whole. A method has been developed for calculating the specific surface area, taking into account the content of bark and rot in wood raw materials, as well as the moisture content of dry chips. The average size of microchips: length 1.79 mm, width 0.35 mm, thickness 0.07 mm. The total surface of 1 kg of microchips is 120 m2. Of these, the largest area of about 81% are the surfaces of layers of wood particles, the shares of the side faces and ends of the microarray, respectively, 15 and 4%. With an average weighted basic density of wood raw materials of 427 kg/m3, the recommended dry resin distribution is 13.7%. At this rate, the calculated specific consumption of dry resin on the surface of wood particles of microchips is 1.14 g/m2. The microarray contains a significant amount of the smallest wood particles of a fraction of 0.5/0 mm – 22.8% of the total mass. The specific surface area of the particles of this fraction is 266 m2/kg, it occupies 50.6% of the total surface area of the microarray. The removal of fine particles of 0.5/0 mm fraction in the amount of 10% of the mass of the microchips allows to reduce the surface area of the microchips from 120 to 104 m3 or by 13.3%, and the surface area of this fraction from 50.6 to 36.4% of the total area of the microchips. With a resin consumption of 13.7%, the calculated specific consumption of dry resin on the surface of the microchip will be 1.32 g/m2. An increase in the specific consumption of resin from 1.14 to 1.32 g/m2 or by 15.8%. Average chip sizes of the inner layer: length 6.25 mm, width 0.88 mm, thickness 0.27 mm. The total surface of 1 kg of chips is 42.9 m2. Of these, the largest area of about 77% are the surfaces of wood particle layers, the shares of the side faces and ends of the microarray, respectively, 20 and 3%. The recommended consumption of dry resin is 10.2%. With this consumption, the even specific consumption of dry resin on the chip surface is 2.38 g/m2. The content of the smallest wood particles of 0.5/0 mm fraction is 5.2% of the total chip mass. The specific surface area of the particles of this fraction is 281 m2/kg, it occupies 34.1% of the total chip surface area of the inner layer. The removal of fine particles of 0.5/0 mm fraction in the amount of 5% of the chip mass reduces its surface area from 42.9 to 30.2 m2 or by 29.6%, and the surface area of this fraction from 34.1 to 2.0% of the total chip area. With a resin consumption of 10.2%, the calculated specific consumption of dry resin on the surface of the wood chips of the inner layer will be 3.38 g/m2. An increase in the specific resin consumption from 2.38 to 3.38 g/m2 or by 42.0%. With a mass fraction of the outer layers of 40%, the removal of 10% of the mass of microchips is 4% of the total flow of dry chips. The similar removal of 5% of small particles from the chips of the inner layer is 3% of the total flow. The sum of the removed fraction of 0.5/0 mm fraction particles is 7% of the total chip mass. Removal of a part of the smallest particles of 0.5/0 mm fraction from the general flow of dry chips leads to an effective increase in the specific consumption of resin over the surface of the remaining chips. When 7% of wood particles of this fraction are removed, the calculated specific resin consumption increases on the surface of the chipboard outer layers from 1.14 to 1.32 g/m2 or by 15.8%, and on the chip surface of the inner layer from 2.38 to 3.38 g/m2 or by 42.0%.

1. Mihajlichenko A.L., Sadovnichij F.P. Drevesinovedenie i lesnoe tovarovedenie. M.: Vysshaya shkola, 1978. 224 p. (In Russ.)

2. Otlev I.A., SHtejnberg C.B., Otleva L.S., Bova YU.A., ZHukov N.I., Konash G.I. Spravochnik po proizvodstvu drevesnostruzhechnyh plit. 2-e izd. pe-rerab. i dop. M.: Lesn. prom-st', 1990. 384 p. ISBN–5–7120–0242–6. (In Russ.)

3. Ugolev B.N. Drevesinovedenie i lesnoe tovarovedenie. M.: GOU VPO MGUL, 2007. 351 p. (In Russ.)

4. Vasil'ev V.V. Aktual'nye tekhnologicheskie problemy proizvodstva sinte-ticheskih smol i drevesnyh plit. Izvestiya Sankt-Peterburgskoj lesotekhnicheskoj akademii, 2020, iss. 230, pp. 173–186. DOI: 10.21266/2079-4304.2020.230.173-186. (In Russ.)