Method for producing compressed panels from cereal crop waste

Abstract

The invention relates to building materials produced by recovering and recycling cereal crop waste. A method for producing compressed panels from cereal crop waste includes the steps of drying, forming and hot pressing. Fibre particles having a size of from 0.9 mm to 30 mm have urea-formaldehyde resin applied thereto first for the outer layers, in an amount of 14-18%, and then for the inner layers, in an amount of 9-15%. Hot pressing is then carried out at a temperature of 150-180°С under a pressure of 6-6.5 MPa for 30 seconds, followed by holding for 5-10 minutes until the pressure decreases to 1-1.5 MPa. The result is an efficient use of cereal crop waste, an environmentally friendly manufacturing process, and panels that have high physical and technical characteristics.

Description

[0001] METHOD FOR PRODUCING PRESSED BOARDS FROM GRAIN WASTE

[0002] The invention relates to construction and insulation materials, waste-free and resource-saving technologies, as well as to ecology, in particular to methods for the disposal and processing of grain crop waste.

[0003] A method for producing construction and insulation boards from straw is known. Bales of clean, dry, light-colored straw are fed into the machine by gravity through loading hatches. After being chopped, the straw is packed into tunnels approximately 1.2 m wide and 5 cm high and compressed under a pressure of 1400 kN / m. 2 at a temperature of 150 to 250°C. No binders are used. A paper facing is glued to the board, after which the board is allowed to cool and cut into pieces of the required length (Staniforth AP Cereal Straw. - M. 1983).

[0004] The disadvantage of this method is that chopping the straw requires a large amount of energy, and the resulting slab of chopped straw has low mechanical strength, requiring it to be covered with paper.

[0005] The objective of the invention is to develop a method for producing a low-cost alternative to raw materials from grain crop waste (straw) for the production of fibreboard with technical properties not inferior to those made from wood fibre.

[0006] The technical result of solving the stated problem is a modification of the production method of pressed straw boards using urea-formaldehyde resin.

[0007] The said technical result is achieved by the fact that a method is proposed for producing pressed boards from straw using: urea-formaldehyde resin, in which straw with a moisture content of up to 18% must be crushed and broken down into short and long fibers, then the resulting fibers are dried in a laboratory drying chamber to 2% moisture, then urea-formaldehyde resin is applied to the fiber particles, and for the outer layers the resin is 14-18%, and for the inner layers - 9-15%, the resulting carpet of resinous particles undergoes a hot pressing process at a temperature of 150-180 °C, while the pressing cycle takes place under a pressure of 6-6.5 MPa for 30 seconds, and the pressure is reduced to 1-1.5 MPa with a long holding time, after pressing the board is cooled at room temperature.

[0008] This method allows the production of pressed boards using straw as the main raw material, which makes it possible to obtain an alternative to fiberboard, with high technical characteristics, as shown in Table 1.

[0009] The result is a straw-fiber board with the following physical and mechanical properties:

[0010] Table 1

[0011] The method for producing pressed slabs is as follows.

[0012] Example: Wheat straw is crushed in a medium-grinding rotary knife mill, resulting in a coarse fraction from 0.9 mm to 30 mm. The resulting straw fiber mass is dried in a vacuum dryer to a moisture content of less than 2%. Urea-formaldehyde resin is applied (with the resin making up 14-18% for the outer layers and 9-15% for the inner layers), and the prepared straw sample, corresponding to the mass of the formed board, is uniformly distributed in the forming cavity of a stationary closed-type mold. Then, in a hydraulic press with heating plates, the mold is heated to a temperature of 180°C. After reaching the specified temperature, the sample is hot-pressed at a pressure of 6.5 MPa for 30 seconds, after which the formed board with a thickness of 6 mm is removed from the mold at a reduced pressure of 1.5 MPa.

[0013] The advantages of the proposed invention are the rational use of grain production waste, the environmental friendliness of the technological process, and the production of a BOARD with high physical and technical characteristics, an alternative to fiberboard.

[0014] Boards produced using this method are a cheap and competitive alternative to fibreboard.

Claims

CLAUSES OF THE INVENTION A method for producing pressed boards from grain crop waste, including drying, forming and hot pressing, characterized in that urea-formaldehyde resin is applied to fiber particles (ranging in size from 0.9 mm to 30 mm), first for the outer layers at 14-18%, then for the inner layers at 9-15%, then hot pressing is carried out at a temperature of 150-180°C under a pressure of 6-6.5 MPa for 30 seconds, followed by holding for 5-10 minutes until the pressure drops to 1-1.5 MPa.

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