Press composition, its preparation and method of production of composite materials based on it

 

(57) Abstract:

Usage: the invention relates to the production of the pressing mass of particles of vegetable origin (shredded wood, fire flax, hemp, GWS-share, sunflower husk, straw cereals) and can be used for the manufacture of products without the use of synthetic binders, construction, finishing assignments used in the furniture and construction industries. With the aim of creating a non-toxic composite materials offered press is a piece of wood particles, containing at least 5% of free sugars, gidrolizuemye agent and does not require the introduction of additional binders in the manufacture of composite materials based on it. The inventive waste wood put a solution of 0.1 - 15.0 wt.h. gidrolizuemye agent is hydrogen peroxide and treat them with superheated steam at 170 - 180C. Steamed wood waste when decompressing become spongy wood pulp, for which further processing is dried to a moisture content of not more than 5%. Wood fibrous mass without the addition of binders formed into and carry out cold-pressing. Hot press the crystals, characterized by high physical-mechanical and hydrophobic characteristics. 3 S. and 1 C.p. f-crystals, 5 PL.

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

The invention can be used in the preparation of raw materials for the manufacture of products for structural, finishing, and other purposes in the furniture and construction industries.

Widely known compositions based on particles of vegetable origin. They typically consist of two main parts: wood filler and a polymeric binder. As polymeric binders used synthetic thermosetting resins prepared from phenols, urea, formaldehyde or isocyanates.

The disadvantage of the described compositions is that they are toxic to humans: during manufacturing and during operation of the finished product vapours of phenol and formaldehyde, providing irritant effect on skin and mucous membranes. Another serious disadvantage of such composition is here binders is a big part of the cost of finished products (about 60%).

Known composition based particles woody raw materials for the manufacture of pressed plates without making the outside of the binder additives and method for producing molded products from wood material without adding binders [patent Application N 94008403/15, class B 27 N 3/11, BI N 13, 1995, S. 62 and RF Patent N 2033319, class B 27 N 3/02, BI N 11, 1995, S. 136, respectively].

The disadvantage of the described compositions and method is that required grinding of raw materials to the size of wood flour (2 to 3 mm), and hot pressing is carried out in harsh conditions: at high specific pressure (30 MPa) and high temperatures (200-220oC), considerably higher than the temperature at which thermal decomposition of wood. The proposed composition and method for producing boards based on the physical impact on wood (temperature, pressure) which, basically, are formed labile hydrogen bonds. High density composites (1300-1400 kg/m3) provides them with high strength properties, but may not provide a high resistance.

Known technical solutions closest to destination and technical nature of the claimed object is a method for compo is wlosy, contains large quantities of free sugars derived from carbohydrate portion of plant material and its processing acid catalyst and steam, and the catalyst charge in the amount of not more than 5 wt.% before steam treatment [RF Patent N 2075384, class B 27 N 9/11, BI N 8, 1997, S. 145].

The composite material produced by hot pressing lignocellulosic material is treated with steam at a temperature of 190-260oC with acid catalyst without further addition of any binders.

The disadvantage of the described compositions and method of reception is the fact that you are using an acid catalyst. The fact that the proposed method of producing composite materials of the particles of lignocellulosic material consists of two main stages: hydrolysis hemicellulose part of the starting materials and the heat of the products obtained in thermoforming process. The catalyst, in which it is proposed to use acid (example using sulfuric acid), playing a positive role in the process of hydrolysis, is retained in the treated wood mass and has a sharply negative destructible impact on wood supply, the process of hot pre is presumed to press composition based particles of lignocellulosic material, containing free sugars, and how it is received, providing the composition defined properties and their variation within the required limits and the method of obtaining a composite material with high physical-mechanical indicators, based on the proposed press composition. The invention is devoid of the above disadvantages associated with destruction effect on the wood pulp used gidrolizuemye agent.

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.

Chemical and functional analysis of wood pulp bartering hydrolysis suggests that it contains a large number of substances (reducing agents, polyphenols, aliphatic acid), having a highly reactive functional group. Under certain conditions (temperature, acidity credibility adhesion to wood fiber.

The implementation of the invention is achieved in that a press-composition of the lignocellulosic material, characterized by the presence of these biodegradable gidrolizuemye agent and free sugars derived from hemicellulose part of the source material. Gidrolizuemye agent, in which it is proposed to use a solution of hydrogen peroxide, in the first stage accelerates the hydrolysis of polysaccharides, decomposing at a simple neutral substances (water, oxygen), and does not destructible actions for wood fibre in the process of hot pressing and subsequent operation.

The implementation of the invention is achieved in that in a method of producing a press-compositions according to the invention on the lignocellulosic material at room temperature cause a certain amount of gidrolizuemye agent dissolved in water, and then the material is treated with steam under pressure at elevated temperatures, while providing defibering rate ligneous particles and rapid hydrolysis of hemicellulose to free sugars.

It is claimed the qualitative and quantitative composition, processing lignocellulosic material restorelocation razvlechenie lignocellulosic material with minimal thermal decomposition of biopolymers plant materials, that allows production of Board materials with good strength and hydrophobic properties at specific pressure not higher than 5 MPa and a temperature of pressing is not above 160oC.

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

The high content of sugars (reducing substances) in the resulting wood mass provides a press of the composition and from the composite materials of high performance properties.

The press arrangement according to the invention is a product of partial hydrolysis of the polysaccharide of the plant material contains free sugars in an amount not less than 5 wt.% and able to be processed into the finished product without the introduction of binders.

The content of hydrogen peroxide in the composition should be from 5.1 to 15.0 wt. hours at 100 wt. including lignocellulosic material. This ratio provides the possibility of hydrolysis of at 170-190oC and allows you to selectively destroy only hemicellulose part of the plant material and to obtain press the song with the highest possible content of its the heat part of the material during the steam treatment, and avoids the occurrence of deep degradation reactions in the process of pressing and operation.

Use gidrolizuemye agent in an amount more than 5 wt.% reduces the temperature and time of heat treatment, resulting in reduced energy costs and increased productivity. The presence of the upper limit when using gidrolizuemye agent due to its impact on accelerating thermal decomposition at hot pressing the resulting wood mass.

Examples of obtaining the proposed press song

Example 1. The mold is placed 100 g of air-dry technological chips birch (size 1-5 cm). The content of the main components in birch wood is lignin - 20.0%, the pulp and 49.2%, easy-hydrolyzed polysaccharides (LGB) is 21.8%.

Wood material is applied pre-dissolved in water (90 - 100 ml) concentrated solution (30%) hydrogen peroxide in the amount of 5.1, Wood chips coated with gidrolizuut agent is maintained at 20oC two hours for uniform impregnation of the whole wood.

Processing of the sample vapor is conducted as follows. The sample is loaded into a preheated who atory for 10-15 C. In the process maintain a constant reactor pressure (1.25 MPa) and temperature. After 10 min after the start of the decompression processing is carried out of the reactor for a time of less than 1.0, in which the treated lignocellulosic material with the steam moves into the receiving cyclone.

The obtained fibrous mass is analyzed for the content of the formed reducing substances (PB), a residual content of easy-hydrolyzed polysaccharides (LGB), moisture content, and after drying to a moisture content of not more than 5%, is used for the manufacture of composite materials. Obtained after decompression wood weight (absolutely dry) contains: RV - 13,2%, LGB to 5.8%, the moisture content of 42%.

Composite material from the resulting fibrous mass (after drying the moisture content of the mass to 5%), were produced by hot pressing under pressure. After formation of the Mat, was carried out by cold-pressing at 1 to 2 MPa, and then was carried out by hot pressing at 150oC when specific pressure of 4 MPa for 1 min/mm of the finished plate. The resulting product was cooled to 50-60oC without pressure relief.

Composite material, pressed - 1220

the tensile strength in bending, MPa - 34,5

water absorption for 24 hours, % - 15,6

swelling for 24 hours, % - 15,5

Table 1 shows examples of making a press-compositions using different quantities gidrolizuemye agent according to the invention, indicating the conditions of handling and compaction, the content of the formed reducing substances (PB), residual easy-hydrolyzed polysaccharides (LGB) and physico-mechanical properties of the obtained materials.

Table 2 shows examples of making a press-songs under different treatment conditions according to the invention with the conditions of extrusion, the content of the formed reducing substances (PB), residual easy-hydrolyzed polysaccharides (LGB) and physico-mechanical properties of the obtained materials.

Table 3 provides examples of making a press-songs from different lignocellulosic materials according to the invention, indicating the conditions of handling and compaction, the content of the formed reducing substances (PB), residual easy-hydrolyzed polysaccharides (LGB) and physico-mechanical properties of the obtained materials.

Sources of information

1. The material of construction of the plates and method of manufacture". Patent application 94008403/15 from 21.03.94 MKI 4 B 27 N 3/00, publ. BI N 13, 1995, S. 62.

2. Patent N 2033319 from 27.10.92, MKI 4 B 27 N 3/02, publ. BI N 11, 1995, S. 136.

3. Patent N 2075384 from 20,03.97, MKI6B 27 K 9/00, publ. BI N 8, 1997, S. 145.

1. Press composition containing particles of lignocellulosic material, which is composed of cellulose, lignin, hemicellulose, free of sugar in an amount not less than 5%, obtained from the carbohydrate portion of plant material and its processing gidrolizuut agent and steam, characterized in that as gidrolizuemye agent use hydrogen peroxide in the following ratio, wt.h.:

Lignocellulosic material - 100

The peroxide - 5,10 - 15,00

2. Press composition under item 1, characterized in that as a lignocellulosic material it contains a material selected from the group consisting of comminuted wood, flax, hemp, GWS-share, straw of cereals and sunflower husk.

3. The method of obtaining press otcu ferry wherein the processing as gidrolizuemye agent use hydrogen peroxide and steam processing is carried out at 170 - 190oC.

4. Method of production of composite materials based on the press of a composition containing cellulose, lignin, hemicellulose, free of sugar and products of their thermal properties, including the formation of the Mat, cold-pressing and hot pressing, wherein the hot pressing is carried out at 120 - 160oC.

 

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