RU2381244C2 - Moulding material, method of obtaining thereof and method of obtaining plate materials on its basis - Google Patents

Abstract

FIELD: construction industry.

SUBSTANCE: invention refers to wood-working, furniture and construction industry. In order to develop non-toxic plate material, it is proposed to use moulding material from plant raw material without using synthetic binders. Moulding material in the form of plant raw material particles containing cellulose, lignine, easy- and difficult-to-hydrolyse polysaccharides and carboxyl groups is obtained by means of cavitation treatment of plant raw material; at that, it contains easy- and difficult-to-hydrolyse polysaccharides 13-18% and 28-37%, correspondingly, cellulose with copper index of 1.7-2.9 g/100 g - 53-58 %, lignine (Komarov) 31-37% and carboxyl groups 0.6-4.9 %.

EFFECT: cheap plate materials having high ecological and physic and mechanical properties are obtained from moulding material.

6 cl, 1 ex, 5 tbl

Description

The invention relates to the production of plate materials such as wood chips from plant 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 industry.

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.

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 [A. Scherbakov. Technology of composite wood materials / A. S. Scherbakov, I. A. Gamova, L. V. Melnikova. - M .: Ecology, 1992. - 192 p.]; steam explosion technology; technology for bioplastics [Bolobova A.V. Theoretical Foundations of Biotechnology of Wood Composites: In 2 books: Book II: Enzymes, Models, Processes / Bolobova A.V., Askadsky A.A., Kondrashchenko V.I., Rabinovich M.L .; [Repl. ed. A.M. Bezborodov]. - M .: Nauka, 2002. - 343 p.]. Each of the above methods has its advantages and disadvantages. The positive side is mainly an increase in the reactivity of the wood complex. 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 is 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 environmental situation.

A known method of producing composite materials from lignocellulosic raw materials [RF Patent No. 200575384], 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 min Further, the composite material is obtained by hot pressing at 210 ° C.

The closest in purpose and technical essence to the claimed invention is a method for producing composite materials from lignocellulosic material obtained by hydrothermal treatment [RF Patent No. 2152966] (prototype). The essence of this method is as follows: a solution of 0.1-15.0 parts by weight is applied to wood waste. hydrolyzing agent - hydrogen peroxide - and process them 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.

The disadvantage of the described 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. The result is dark colored tiles 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.

In our invention, these drawbacks are eliminated due to the applied cavitation processing technology.

The essence of our invention lies in the fact that the press mass in the form of plant materials (sawdust, cereal straw, etc.) containing free sugars is obtained by cavitation treatment. When pressing the resulting press mass, a composite material is obtained with physical and mechanical properties that meet the requirements of European standards.

As a result of cavitation exposure from pine wood without and with the addition of a hydrolyzing agent - sulfuric acid - a mass is formed with a content of easily and hardly hydrolyzable polysaccharides 13-18% and 28-37%, respectively, a cellulose content of 53-58% and a copper number of 1.7 -2.9 g / 100 g, the lignin content according to Komarov is 31-37%. The content of carboxyl groups is 0.6-4.9%. Thus, a chemical and functional analysis of the wood pulp subjected to cavitation treatment indicates that it contains a large number of substances having highly reactive functional groups. Under certain molding conditions, ligno-carbohydrate bonds that are similar in type and properties to natural bonds in the original wood, as well as recombination with the formation of additional structures and the appearance of new carbon-carbon and oxygen-carbon bonds, are recreated from these substances at the contact points of wood particles. polymer substances with high adhesion to the filler were obtained.

The implementation of the invention is achieved by the fact that in the method of producing a press mass according to the invention, plant materials (sawdust or particles of cereal straw with a moisture content of 3-8%, a fraction of up to 1.25 mm and 2 cm, respectively) are placed in a container with water (the hydraulic unit is 10 ) without or with the addition of a hydrolyzing agent - sulfuric acid (concentration up to 1%). The mass is subjected to cavitation for various periods of time (15-120 min). The process is accompanied by spontaneous heating of the mixture to 95 ° C. This treatment provides the necessary intensification of the processes of particle dispersion and the rapid hydrolysis of hemicelluloses, degradation of lignin with the formation of more reactive compounds.

It is the claimed qualitative and quantitative composition, cavitation treatment of plant materials without and with a hydrolyzing agent that, according to the method, provide the best fluidity of the press mass, which makes it possible to produce plate materials with good strength and hydrophobic properties in milder conditions - at a specific pressure of not higher than 11 MPa and temperature pressing not higher than 160 ° C.

The high content of sugars (reducing substances) in the resulting press mass provides high operational properties obtained from the slab materials.

The press mass according to the invention is a product of partial hydrolysis of the polysaccharide part and partial degradation of lignin, which does not have low molecular weight boiling substances of various hazard classes, and is capable of being processed into finished products without the addition of binders.

The sulfuric acid content of 1 wt.h. per 100 parts by weight of plant material provides the possibility of carrying out the process of hydrolysis and degradation already at 60-70 ° C under cavitation conditions.

Examples of the proposed press mass.

Example 1

1000 g of air-dried sawdust of pine wood (fraction 0.6-1.2 mm) are placed in a container. The content of the main components in pine wood is: cellulose (copper number 1.8) - 52.2%, lignin - 29.2%, easily hydrolyzable polysaccharides (LHP) - 18.5%, hard-hydrolyzable polysaccharides (THP) - 42.0% .

0.01 m ^{3 of} water (hydromodule 10) is added to the wood material, into which 10 g of concentrated sulfuric acid is preliminarily added — a hydrolyzing agent.

The mass is subjected to cavitation (productivity 9 t / h) for 60 minutes, maintaining the temperature in the reaction zone of the cavitator 60-70 ° C.

The resulting mass is dried to a moisture content of 10% and used for the manufacture of plate materials. After cavitation treatment, the obtained press mass contains LHP - 14.3%, TGP - 33.0%, copper number of the selected pulp - 2.6. The structure of the obtained products is identified by IR spectroscopy.

Plate materials were made by hot pressing under pressure. After carpet molding, cold pressing was carried out at 1 MPa, and then hot pressing was carried out at a temperature of 140 ° C and a specific pressure of 7.5 MPa for 1 min / mm of the finished plate. After that, the resulting product was cooled to 50-60 ° C without relieving pressure.

Plate material pressed from the press mass obtained according to this example has the following physical and mechanical characteristics:

density, kg / m ³ 1270 bending strength, MPa 22.4 thickness swelling in 24 hours,% 12.3 water absorption in 24 hours,% 20,2 humidity% 8.5

Table 1 shows examples of the preparation of press masses under various conditions, the content of LGP and THP, the carboxyl groups of the isolated dioxane-lignin, the copper number of the selected cellulose and the physicomechanical characteristics of the resulting plate materials.

Table 2 shows examples of the manufacture of plate materials at various pressing temperatures according to the invention, indicating LHP and TGP, the copper number of the selected pulp and the physical and mechanical properties of the obtained plate materials.

Table 3 shows examples of the manufacture of plate materials at various pressing pressures according to the invention, indicating LGP and TGP, the copper number of the selected pulp and the physical and mechanical properties of the resulting plate materials.

Table 4 shows examples of the manufacture of plate materials with different moisture content of a wood carpet according to the invention, indicating LHP and TGP, the copper number of the selected pulp and the physical and mechanical properties of the resulting plate materials.

Table 5 shows examples of the manufacture of plate materials using modifying additives according to the invention with an indication of LHP and TGP, the copper number of the selected pulp and the physical and mechanical properties of the resulting plate materials.

Claims (6)

1. The press mass in the form of particles of plant materials containing cellulose, lignin, easily and hardly hydrolyzable polysaccharides and carboxyl groups, characterized in that it is obtained by cavitation processing of said 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%. 2. The press mass according to claim 1, characterized in that the crushed wood or cereal straw is used as plant material. 3. The press mass according to claim 1, characterized in that it is obtained by cavitation treatment of plant materials with the addition of a hydrolyzing agent in an amount of 1 wt.h. per 100 parts by weight plant materials. 4. A method of obtaining a press mass according to one of claims 1 to 3, comprising placing the plant material in a container of water, which is subjected to cavitation treatment for 15-120 minutes and, due to spontaneous heating of the mixture to 95 ° C, destroy the cell wall without significant destruction of the main structural components. 5. The method according to claim 4, characterized in that the cavitation treatment of plant materials is carried out with the addition of a hydrolyzing agent in an amount of 1 wt.h. per 100 parts by weight plant materials. 6. A method of producing plate materials from a press mass according to one of claims 1 to 3, including carpet molding, cold pressing and hot pressing of plant materials, which is carried out at 120-160 ° C and a pressure of 2.5-11 MPa with carpet moisture 5-20%.