RU2637550C2 - Method for production of composite materials - Google Patents

Abstract

FIELD: technological processes.

SUBSTANCE: invention can be used for manufacture of articles of construction, finishing and other purposes in furniture and construction industries. The method for production of composite materials consists in treatment of vegetable raw material with overheated water steam, in which peat or mixture of peat with wood is used as vegetable raw at weight ratio = 1:1, and treatment of raw material with overheated water steam provided at 190-210°C and pressure 1.42 -2.03 Mpa for 10 min followed by decompression, drying of press-mass to moisture content of 5% and further hot pressing of produced press-mass at temperature of 120°C, 40 Mpa pressure for 5 min.

EFFECT: extension of raw material base by using peat for production of composite materials, possibility to produce additional amount of binding humid substances from it, reduced cost of the process by eliminating the catalysts leading to additional expenses and corrosion of process equipment.

2 tbl

Description

The invention relates to the production of composite materials such as wood chips from plant materials, including humic peat raw materials, without the use of synthetic binders. The invention can be used for the manufacture of structural, finishing and other products in the furniture and construction industries.

Plate materials such as particleboard from plant materials are traditionally made using synthetic thermosetting resins - phenol-formaldehyde, urea-formaldehyde, etc., which have a number of disadvantages. The manufacturing process is toxic. During operation, formaldehyde is released and has an irritating effect on the skin and nervous system of a person. Another disadvantage is that synthetic binders are a product of petrochemical industries and are quite expensive [AS Scherbakov Technology of composite wood materials / A.S. Shcherbakov, I.A. Gamova, L.V. Melnikova. - M.: Ecology, 1992. - 192 p.].

There are various methods of producing plate materials from crushed wood without the use of binders: a single-stage method for producing piezothermoplastics; a two-stage method for producing plastics from hydrolyzed sawdust; technology for producing ligno-carbohydrate wood plastics [Shcherbakov A.S. Technology of composite wood materials / A.S. Shcherbakov, I.A. Gamova, L.V. Melnikova. - M.: Ecology, 1992. - 192 p.].

Known methods have their advantages and disadvantages. The positive side is mainly an increase in the reactivity of lignocellulosic materials. Depending on the technological conditions, destructive processes occur in the wood, which differ in the degree of degradation of the main components. The main disadvantages of these methods are the use of high pressures (up to 20-30 MPa) and temperature (170-225 ° C), i.e. high material and energy intensity, and in some cases the need to neutralize and regenerate the product, which worsens the ecology of the processes.

A known method of producing composite materials from lignocellulosic raw materials, which consists in processing lignocellulosic crushed raw materials that do not contain free sugars, steam under pressure at 190-260 ° C to release hemicelluloses for 15 s - 10 minutes Further, the composite material is obtained by hot pressing at 210 ° C [RF patent No. 2075384, IPC C08L 97/02. publ. 03/20/1997, bull. No. 8].

The disadvantage of the described composition and the method of its preparation is that a catalyst is used and too stringent modes of steam treatment and pressing are selected. The reason is that the proposed method for producing composite materials from particles of lignocellulosic material consists of two main stages: hydrolysis of the hemicellulose part of the feedstock and thermosetting of the obtained products during hot molding.

The catalyst, which is proposed to use acid (for example, the use of sulfuric acid), having played a positive role in the hydrolysis process, is stored in the treated pulp and has a negative destructive effect on the pulp components both during pressing and subsequent use of the products. Rigid modes of steam treatment and pressing lead to an increase in energy costs and intensification of thermal degradation of the structural components of the lignocellulosic complex.

A known method for producing composite materials from lignocellulosic material obtained by hydrothermal treatment of plant materials with a solution of 0.1-15.0 wt. including hydrolyzing agent - hydrogen peroxide - with further processing of it with superheated steam at 170-180 ° C. Steamed wood waste during decompression turns into pulp wood pulp, which is dried to a moisture content of not more than 5% for subsequent processing. A pulp without the addition of binders is molded and cold pressed. Hot pressing is carried out at 120-160 ° C at a pressure of 4.0 MPa for 1 min per 1 mm of the finished product [RF patent No. 2152966, IPC C08L 97/02, publ. 07/20/2000, bull. No. 20].

A disadvantage of the known method is that the properties of the products obtained by this method strongly depend on the nature of the raw materials used and the modes of their pretreatment. As a result, the tiles are dark in color due to partial resinification. Upon receipt, the highly energy-intensive method of preparing raw materials with superheated steam and decompression, as well as complex hardware design, is used.

Known press mass in the form of particles of plant materials containing cellulose, lignin, easily and hardly hydrolyzable polysaccharides and carboxyl groups, which is obtained by cavitation processing of plant materials, while it contains easily and hardly hydrolyzable polysaccharides 13-18% and 28 -37%, respectively, cellulose with a copper number of 1.7-2.9 g / 100 g - 53-58%, Komarov lignin 31-37% and carboxyl groups 0.6-4.9% [RF patent No. 2381244, IPC C08L 97/02, publ. 02/10/2010, bull. No. 4].

The disadvantage of the described composition and method for its preparation is the use of a sulfuric acid catalyst. The acid catalyst, having played a positive role in the hydrolysis process, is retained in the treated pulp and has a negative destructive effect on the pulp components both during pressing and subsequent use of the products. In addition, its use leads to additional corrosion of technological equipment.

Known press composition for the manufacture of composite materials with improved performance by pre-processing lignocellulosic materials with water at room temperature for 20-120 minutes, followed by steam treatment and further hot pressing [RF patent No. 2277554, IPC C08L 97/02, publ. 06/10/2006, bull. No. 16]. The disadvantages of this technical solution are: two-stage process and its total duration up to 120 minutes

The claimed invention differs from analogues in that the raw material base expands due to the use of peat, the use of which allows to obtain significant quantities of its own binders in the composition of composite materials due to the presence in addition to lignin and polysaccharides in addition to its composition peat humic substances with pronounced binding properties [Kopanitsa N.O., Kudyakov A.I., Kovaleva M.A. Peat-wood heat-insulating building materials. - Tomsk: SST Publishing House, 2009. - 183 p.].

In the claimed invention, the disadvantages of existing analogues are eliminated as follows: the use of peat allows you to expand the raw material base and to obtain significant amounts of proprietary binders in the composition of composite materials during the manufacturing of composite materials due to the presence of additional humic substances in the composition of peat containing a wide range of different reactive oxygen-containing functional groups, and the exclusion of the use of catalysts (sulfuric acid and hydrogen peroxide a) prevents corrosion of processing equipment.

The essence of the claimed invention lies in the fact that a method for producing composite materials has been developed, which consists in processing vegetable raw materials with superheated steam, characterized in that peat or a mixture of peat with wood is used as vegetable raw materials, and processing of raw materials with superheated steam is carried out at 190-210 ° C and a pressure of 1.42-2.03 MPa for 10 min, followed by decompression, drying of the press mass to a moisture content of 5% and further hot pressing of the resulting press mass at a temperature of 120 ° C, pressure 40 MPa 5 minutes

EFFECT: expansion of the raw material base by using peat to obtain composite materials, the possibility of obtaining an additional amount of humic binders from it, cheaper process due to the exclusion of catalysts, leading to additional costs and corrosion of technological equipment.

The implementation of the claimed invention is achieved as follows.

Samples of sawdust of vegetable raw materials with a volume of 0.5 liter are loaded into a reactor of an explosive autohydrolysis apparatus preheated to 190-210 ° C, the design of which allows the material to be heated with steam to a predetermined temperature. During the steam treatment, a constant pressure (1.62-2.03 MPa) and temperature (190-210 ° С) are maintained in the reactor. 10 minutes after the start of treatment, the reactor is decompressed by an explosive method (for a period of not more than 1 s), as a result of which the processed composite material based on plant materials is transferred to the receiving cyclone together with steam.

Composite material from the resulting mass after it was dried to a moisture content of 5% was prepared by hot pressing under a pressure of 40 MPa and at a temperature of 120 ° C for 5 minutes. After cooling, the tile is removed from the press, and its properties are studied. For the obtained composite materials, the density, ultimate strength in bending, water absorption and swelling are determined in accordance with GOST 10634-88 and 10635-88.

Table 1 shows the influence of the conditions for processing raw materials with water vapor on the composition of the obtained composite materials. Table 2 shows data on the influence of the processing conditions of peat and a mixture of peat and pine wood with steam on the properties of the obtained composite materials.

* a mixture of 50% peat and 50% sawdust of pine wood (fraction 0.5-1.0 mm).

As shown by studies of the properties of the obtained composite materials (table 2), composite materials based on peat and a mixture of peat and wood obtained after treatment with superheated steam and subsequent hot pressing satisfy the requirements of GOST for strength characteristics, water absorption and swelling.

Claims (1)

A method of producing composite materials, which consists in processing plant materials with superheated water vapor, characterized in that peat or a mixture of peat and wood is used as plant materials in a mass ratio of 1: 1, and the processing of raw materials with superheated water vapor is carried out at 190-210 ° C and a pressure of 1.42-2.03 MPa for 10 min, followed by decompression, drying of the press mass to a moisture content of 5% and further hot pressing of the resulting press mass at a temperature of 120 ° C, a pressure of 40 MPa for 5 min.