Press composition for the manufacture of chipboard and method for producing chipboard on the basis of the press - composition

 

Use: in the manufacture of chipboard and fibre materials used in the furniture and construction industries. Press composition contains particles of lignocellulosic material containing lignin, cellulose, hemicellulose, free of sugar, formed by sequential processing gidrolizuemye agents - sulfuric or phosphoric acid and steam and the modifying agent: ferric sulfate or chloride of zinc, or copper chloride. The implementation of the invention is achieved by the fact that steamed at a temperature of 170-190oWith wood pulp introduce the modifying agent. Plate material produced by hot pressing of the composition at a temperature of 100-120oC. the present invention allows to obtain a plate material of low toxicity, characterized by high physical and mechanical properties. 2 S. and 1 C.p. f-crystals, 5 PL.

The invention relates to the production of chipboard-based particles of vegetable origin, in particular to press the composition and method of production of composite materials based on it.

The invention can be used for the manufacture of products constructionistic of plant origin, for example wood, known for a long time. For bonding particles of wood use synthetic thermosetting resins prepared from phenols, urea and formaldehyde.

Despite the constant improvement in these compositions, they have several serious drawbacks. They are toxic to humans, because in the process of exploitation of finished products, vapours of phenol and formaldehyde, providing irritant effect on the skin and nervous system. Another disadvantage is that the synthetic binding of the road, as they are made from petrochemical products. The cost of the binders is a big part of the cost of finished products (about 60%).

A known method of manufacturing a wood-fiber material, whereby to reduce toxicity, the authors propose to use as a binder adduct is neutralized tall oil pitch and a water-soluble salts of polyvalent metals. The use of production waste - tall pitch allows you to receive and economic effect. [RF patent 2012486, CL 27 N 3/04, 1994].

The disadvantage of this method are numerous technological operations related to obtaining binding: nakie the application of binder atomization of the melt.

Known technical solutions closest to destination and technical nature of the claimed object is a method of obtaining a composite material of the particles of lignocellulosic material, which is composed of cellulose, lignin, hemicellulose, which contains large quantities of free sugars derived from carbohydrate portion of plant material and its processing acid catalyst and steam, and the catalyst is applied to the material in a quantity not more than 5 wt.% prior to steam treatment. [RF patent 2075384, CL 27 K 9/00, 1997].

The composite material produced by hot pressing lignocellulosic material is treated with steam at a temperature of 190-260oWith time, without imposing any binders.

The method eliminates the use of synthetic binder type phenol-formaldehyde resins, however, it is not possible to obtain plates with high physical-mechanical indicators.

The aim of the invention is the improvement of physico-mechanical properties of plate materials and reducing energy consumption by reducing the temperature pressing.

The invention consists in that the press-composition-based particles lignier), to significantly increase the mechanical properties of plate materials.

Chemical and functional analysis of wood pulp after steam treatment under pressure shows that it contains a large number of substances (reducing agents, polyphenols, aliphatic acid), having a highly reactive functional group. Reducing substances (sugar), produced in large quantities (up to 15-20%) in wood fiber, have a carbonyl group, prone to nucleophilic attach. Native lignin, as the polyfunctional polymer contains phenolic and alcoholic hydroxyl, carbonyl (aldehyde and ketone) groups, double bonds, which ensures a high reaction activity in various reactions.

By heating the hydrolyzed pulp happen polycondensation reactions, including carbonyl groups formed sugars. Used salt can catalyze both the formation of hydroxymethylfurfural, one of the main products of the dehydration of sugars, and the reaction between phenol plot lignocellulosic material and the carbonyl group of sugar or hydroxymethylfurfural.

Osushestvleniu free of sugar, enter salt of iron, copper or zinc in the amount of 0.25 to 1.0 wt.h. on 100 wt.h. steamed and dried wood pulp or of vegetable mass of agricultural wastes (straw, chaff, flax).

The implementation of the invention is achieved in that in a method of producing plate materials according to the invention, the metal salt is applied to the lignocellulosic material after steam treatment, followed by its drying, molding, carpet, cold-pressing and hot pressing at a temperature of 100-120oC.

The claimed composition is press-composition and processing of lignocellulosic material by steam under pressure to provide, according to the method, sufficient razvlechenie lignocellulosic material with minimal thermal decomposition of biopolymers plant materials, thus enabling production of Board materials with good strength and hydrophobic properties at specific pressure not exceeding 3-5 MPa and a temperature of the pressing 100-120oC.

Use gidrolizuemye agent allows for the processing of wood material in a short period of time (1-15 minutes).

Press the composition according to the invention, is a product of partial hydrolysis of the policy the Oia without the introduction of binders.

The use of catalytic amounts of the modifying agent can significantly improve the mechanical properties of the plates and to carry out the process of pressing wood pulp at a temperature of 100-120oWith that leads to a reduction in energy costs and reducing the cost of the plates.

The upper and lower limits of the content of the modifying agent in the press of the composition is determined experimentally and is substantiated by the examples in the table.1 and 2.

An example of obtaining the proposed press composition.

The mold is placed 100 g of air-dry technological chips birch (size 1-5 cm). In the chips is applied pre-dissolved in water (90-100 ml) concentrated sulfuric acid in the amount of 0.5 g Wood chips coated with gidrolizuut agent is maintained at 20oWith two hours for uniform impregnation of the whole wood.

Processing of the sample vapor is heated to 180oWith the reactor, the design of which allows to maintain a constant pressure (1.25 MPa) and temperature. After 10 min after the start of treatment is decompression of the reactor for a time of less than 1.0, in which the treated lignocellulosic material with the steam moves in that iron(2) based on 100 g of air-dried pulp), then the mass is dried to a moisture content of 5%.

After formation of the Mat is cold-pressing at 1-2 MPa, and then hot pressing at 100oWith specific pressure of 4 MPa for 1 min per 1 mm of the finished plate. After that, the plate is cooled to 50-60oWith no pressure relief.

Composite material extruded from the press of the composition obtained in this example has the following characteristics: Density, kg/m3- 1330 tensile strength in bending, MPa - 44,9 Water for 24 hours, % - 10,7 Swelling for 24 hours, % - 16,9 table. 1 shows examples of making a press-compositions using various amounts of ferric sulphate according to the invention, indicating the conditions of handling and compaction properties of the obtained materials.

In table. 2 shows examples of making a press-compositions with different amounts of zinc chloride, according to the invention, indicating the conditions of processing, pressing and properties of produced materials.

In table. 3 and 4 show examples of composite materials from plant agricultural waste (straw, buckwheat, fire flax) using different amounts mod is litnih materials.

In table. 5 shows examples of composite materials from wood pulp at different temperature pressing.

Claims

1. Press composition for the manufacture of chipboard, containing particles of lignocellulosic material, which is composed of cellulose, lignin, hemicellulose, free sugars derived from carbohydrate portion of plant material and its processing gidrolizuemye agents - acid and then steam, characterized in that it contains particles, is obtained when using as gidrolizuemye agent sulfuric or phosphoric acid, and further includes a modifying agent selected from the group consisting of ferric sulfate (2), zinc chloride and copper chloride.

2. Press composition under item 1, characterized in that as a lignocellulosic material it contains a material selected from the group of: shredded wood, fire flax and straw of cereal.

3. The method of obtaining chipboard based on the press of a composition containing particles of lignocellulosic material, which is composed of cellulose, lignin, hemicellulose, free of sugar and products of their thermal properties, formed at about the second pressing and hot pressing, characterized in that use press composition under item 1 and the hot pressing is carried out at 100-120oC.

 

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