A method of manufacturing a molded modified wood

 

(57) Abstract:

Essence: in the method of manufacturing a molded modified hardwood impregnation of wood blanks aqueous solution of urea carried out under vacuum. Pressing is carried out in two stages with pressure relief between them, and on stage I pressed material can withstand 5-25 min, at stage II stand 45-95 minutes Later after pressing, heat treatment is carried out at a temperature of 150-180°C for 60-150 minutes impregnation of the workpieces is carried out in the presence of phosphoric acid at a ratio of urea and phosphoric acid from 2.5 : 1 to 30 : 1. The consumption of urea is 5-15% by weight of absolutely dry wood blanks. 2 C.p. f-crystals, 2 tab.

The invention relates to woodworking industry and can be used in the manufacture of flooring, furniture parts, parts for decoration of halls and wall panels.

Known methods for producing molded modified wood by impregnation of wood urea, drying and pressing (1).

The disadvantage of this method is the duration of the process.

The closest analogue of the claimed technical solution tapetki wood blanks aqueous solution of urea, pressing at a pressure of 0.5 to 3 MPa and a temperature of 160-180aboutWith and heat treatment (2).

This impregnation is carried urea solution with a concentration of not more than 30% for 1-9 days., and thermal processing of impregnated wood is carried out before pressing at a temperature of 110-120about.

The disadvantage of this method is that during heat treatment to remove the plasticizer (H2On and on subsequent processing stages - pressing at a temperature of 160-190aboutWith the reduction of the quantity of plasticizer has a negative effect on the quality of pressed wood. Additionally, the known method is also a long process.

New technical result of the claimed method is the intensification of the process while improving the quality pressed wood.

Achieved a new technical result due to the fact that in the method of manufacturing a molded modified wood, mainly for flooring, by impregnation of wood blanks aqueous solution of urea, pressing at a pressure of 0.5 to 3.0 MPa and a temperature of 160-180aboutWith and heat treatment, impregnation carried out under the th material can withstand 5-25 min, at stage II stand 45-95 min, and heat treatment is carried out after pressing at a temperature of 150-180aboutC for 60-150 minutes

Impregnation of wood blanks urea can be carried out also in the presence of phosphoric acid from 2.5:1 to 30:1. Thus, urea, take in the amount of 5-15% by weight of absolutely dry wood blanks, and phosphoric acid in amount of from 0.5 to 2.0% by weight of absolutely dry wood blanks.

It is known that to intensify the impregnation of wood by conducting impregnation under vacuum (journal Paper industry", N 6, 1970).

However, the proposed method using the impregnation method "vacuum - pressure - vacuum" (instead of soaking the prototype) provides a uniform introduction of the urea solution in the cell wall of wood and remove excess mortar from her pores and capillaries, which is necessary to put the urea worked during subsequent pressing of the most efficient.

A positive effect in the two-stage compression wood is associated with pressing billets with high water content and is as follows.

The water in the first stage of pressing spectralis limnogeology complex. Urea increases the plasticization. In General this leads to a softening of the high-molecular components at the temperature of extrusion and napressovyvaniya wood under pressure.

The pressure relief is required for the free removal of the main part of the water in the form of steam. Reducing the drying time compared to drying in a compressed state. The physical state of the soft component is not changed. The rise of pressure in the second stage up to a maximum value is reached, the specified degree of compaction. Then spend a stepped pressure relief.

At this stage undergo chemical reactions of transformation of the main wood components and their interaction with the urea and products terupravleniya. Plasticizing effect as drying and turning disappears, and macromolecular reaction knitting stabilized compressed wood.

Immediately after pressing the wood comes to deepening of chemical reactions on the heat treatment in the chamber by the flow of hot air. The advantage of separate heat is the rational use of expensive baling equipment and better removal leave

The invention is illustrated by the following examples.

P R I m e R 1. A method of manufacturing a molded modified aspen wood is as follows. Air-dry the workpiece from aspen size HH (initial density blanks 470 kg/m3) loads in a vertical position in the autoclave, create a vacuum 0,095 MPa and maintain the workpiece 10 minutes Then the autoclave serves a 10% solution of urea (flow rate 15% of absolutely dry blanks), establish atmospheric pressure and withstand the workpiece 10 min, then the solution is drained. The total duration of the impregnation 30 minutes

Then the samples are subjected to two-step compaction process in the following modes:

I step pressing. Increase of pressure up to 2.5 MPa (within 30 s), Parking 5 min and discharge pressure;

II stage. Increase of pressure up to 2.5 MPa (within 10 s), Parking for 45 min, then manual reset pressure to atmospheric;

Samples extracted from the frame and heat treated in a Cabinet with adjustable temperature at a temperature of 170aboutC for 120 minutes

The obtained modified aspen wood condition within 5 days to a moisture content of 6% and feel by current standards.

The test results of the modified wood are presented in table.2.

P R I m e R s 4-6. A method of manufacturing a molded modified aspen wood is carried out analogously to example 1, but as an interim solution using a solution containing urea in the presence of phosphoric acid. The specific ratio of urea: phosphoric acid in the impregnating solution, as well as the specific values of the technological parameters of the implementation stages of the method are given in table.1.

The test results of the modified wood are presented in table.2.

P R I m e R s 4-6. A method of manufacturing a molded modified aspen wood is carried out analogously to example 1, but as an interim solution using a solution containing urea in the presence of phosphoric acid. The specific ratio of urea: phosphoric acid in the impregnating solution, as well as the specific values of the technological parameters of the implementation stages of the method are given in table.1.

The results of the tests of the modified tree is a private aspen wood is as follows. Air-dry the workpiece from aspen size HH impregnated with 15% urea solution by the method of hot-cold bath for 24 h, and then carry out the heat treatment of the impregnated wood at a temperature of 180aboutC. the Heated billet is pressed at a pressure of 2.5 MPa and a temperature of 170aboutWith over 360 minutes

The obtained modified aspen wood condition within 5 days to a moisture content of 6% and feel by current standards.

The test results of the modified wood are presented in table.2.

The analysis of table. 1,2 shows that the proposed set of features ensures the achievement of a new technical result, both in terms of process intensification (example 1-6 - the duration of the impregnation 20-40 min; duration of pressing 55-115 min; duration of heat treatment 150-180 min; example 9 - prototype - the duration of the impregnation 1440 min; duration of pressing 360 min; duration of heat treatment 360 min, and improve the quality of the target material is an example of 1.5 (the proposed method) at 40-50 MPa higher Flexural strength, specific strength greater 0.08 / , and the water absorption is reduced by 1.3-2.1 g/is but for flooring by impregnation of wood blanks aqueous solution of urea, pressing at a pressure of 0.5 to 3.0 MPa and a temperature of 160-180oWith and heat treatment, characterized in that the impregnation is carried out under vacuum, the pressing is carried out in two stages with pressure relief between them, and at the first stage of the compression material can withstand 5-25 min, in the second stage stand 45-95 min, and heat treatment is carried out after pressing at 150-180oC for 60-150 minutes

2. The method according to p. 1, characterized in that the impregnation of the blanks urea is carried out in the presence of phosphoric acid at a ratio of urea and phosphoric acid from 2.5:1 to 30:1.

3. The method according to PP. 1 and 2, characterized in that the urea charge in the amount of 5-15% by weight of absolutely dry wood blanks, and phosphoric acid in amount of from 0.5 to 2.0% by weight of absolutely dry wood blanks.

 

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