SU1613332A1 - Method of producing wood particle boards - Google Patents

Abstract

The invention relates to the woodworking industry and can be used in the manufacture of wood-based panels. The purpose of the invention is to reduce the release of formaldehyde from the plates. For this, single-layer slabs with a thickness of 16 mm and an average bulk density of 760 kg / m ³ are made by mixing wood chips with a moisture content of 2-3% with a urea-formaldehyde resin KF-MT and a modifying additive or their mixture. Pneumatic molding of the chip carpet is then carried out. Hot pressing was carried out at 160 ° C, specific pressure of 2.9 MPa and pressing time of 0.31 min / mm of the finished plate. The modifying additive is prepared in a vertically heated container with a stirrer. The capacity is filled with the calculated amount of water and water glass, heated with stirring to 40-60 ° C. Then carbamide, ammonium silicofluoride, aluminum sulfate and casein glue in the powder are sequentially poured, mixed with each component until a homogeneous mixture is obtained. The amount of dry ammonium silicofluoride to dry resin is 4%. Use the following ratio of components in the modifying additive, wt.%: Ammonium silicofluoride 10-30

liquid glass (dry basis) 0.05-0.4

carbamide 15-40

aluminum sulphate 0.2-2.5

casein glue powder 5-16

water the rest. 4 tab.

Description

70.68 19.08 8.48 0.35

1.41

or with their mixture; pneumatic molding of particleboard carpet: by hot pressing at 160 ° C, specific pressure of 2.9 MPa and pressing time of 31 min / mm of the finished plate.

The modifying additive is prepared in a vertically heated container with a stirrer. The calculated amount of water is poured into the container, water glass is heated, with stirring, to 40-60 ° C, the carbamide, silicon oil and 1RISM ammonium, aluminum sulfate and | keein glue in the powder are subsequently poured. With each com- pant; mix until a homogeneous mass is obtained. The casein glue used is casein glue in powder, GOST 3056-74, of the following composition | wt.%:

j Technical acid casein

; Hacheen lime

I sodium fluoride

: Copper sulfate

i Kerosene1 1

P examples of the binder ratio of dry

Ammonium fluoride to dry resin

| about 4 wt.%.

Examples of formulations of the composition of the modifying additive based on aqueous solution of ammonium silicofluoride and their characteristics are given respectively in Table. 1 and 2. In table. Table 3 shows examples of values of binder indicators based on the urea-formaldehyde resin and modifying additives. Table. 4 - values of indicators of plates made as || 1 when pre-mixing the resin with | Iodificating additive (indicated in the number 1), and when applied separately, moles and modifying additives on wood chips (indicated in the denominator). I Isolation of formaldehyde from plates |

ten

15

20

25

thirty

35

40

with chromotropic acid according to the West German FRI method after holding the sample plates at 40 ° C for 24 hours. The physicomechanical indicators of the plates are determined after 3 days of exposure of the plates in natural conditions.

Thus, the implementation of the invention in the industry of wood-based panels on urea-formaldehyde resin makes it possible to produce class E 1 boards of toxicity instead of boards of class E 2 according to a known method.

Claims (1)

The invention of the method for manufacturing chipboard boards, comprising mixing dried wood particles with a urea formaldehyde resin and a modifying additive based on an aqueous solution of ammonium fluorofluoride or mixtures thereof, the subsequent formation of a carpet and hot pressing, different in that that, in order to reduce the release of formaldehyde from the plates, the modifying additive additionally contains liquid glass, urea, aluminum sulfate and casein glue in the powder in the following ratio of components to tsiruyuschey additive wt. Ammonium silicofluoride 10-30 Liquid glass (dry basis) 0.05-0.4 Urea 15-40 Aluminum sulphate or 0.2-2.5 Casein powder glue 5-16 Water Else In this case, the modifying additive is prepared by successive mixing by heating in water of liquid glass, urea, ammonium silicate, aluminum sulphate and casein glue in the powder. Examples of formulations composition modifying additives Table Properties of an aqueous solution of the modifying additive Table 2 Properties of binders with an aqueous solution of the modifier add ;, v1i b l and c a 3 Chipboard Performance T a b l and c a 4