RU2496634C2 - Method of wood anti-fire and bio-protection processing - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to woodworking industry. Proposed method consists in thermal impregnation with aqueous solution including nitrogen-containing component and borax. Said nitrogen-containing component represents carbamide at the following ratio of components in wt %: borax -10-1, carbamide - 10-15, water making the rest. Additionally, lime is used in amount of 20-30% with respect to amount of water. Proposed method comprises saturation of wood with aromatisers by injecting the latter into closed chamber with wood in amount of 1-2 g per 1 m³ of wood and holding it for 24 hours.

EFFECT: higher quality of treatment, longer life of wooden articles.

3 cl

Description

The invention relates to the woodworking industry, and in particular to methods for impregnating wood billets with protective compounds, to obtain non-combustible, rot-resistant materials and structures.

There are a large number of ways to protect wood products in order to increase their service life and quality, containing various techniques, using a variety of solutions.

Known methods of fire protection of wood, including treatment with compositions containing soda ash, boric acid and sodium fluoride in wt.%, Respectively: 1-15, 1-5,2, the rest of the water, OST 13-135-82. "Protective agents for wood." Solutions of fire-retardant drugs FBS and BS-13. Technical requirements. Min forestry and pulp and paper industry of the USSR.

The disadvantage of these methods is the use of compounds with high toxicity due to the use of sodium fluoride.

There is also known a method of fire retardant impregnation of wood (No. 2307736, B27K 3/52, publ. 10.10.2007) with a composition containing an aqueous solution of phosphoric acid and urea, a film-forming alcohol solution of tetraethoxysilane with ultrafine powder (UDP), selected from aluminum or fluoroplastic powder, with the following ratio of components, wt.%:

Orthophosphoric acid 20-30 Urea 15-25 Tetraethoxysilane 1.2-2.5 Monohydroxy alcohol 12.5-13.0 UDP 0.06-0.08 Water Rest

The disadvantages of the method of impregnation of wood with a known composition are the processing time, because the impregnating composition is applied in 2-3 layers, the drying time of each layer at room temperature is 2 hours and a significant number of components of the composition.

The closest technical solution to the claimed invention is a method of processing wood, which consists in sequentially impregnating wooden structures at a temperature of 10-60 ° C with two aqueous solutions, which are fire-retardant compositions for primary and secondary (secondary) impregnation. The solution for primary impregnation contains inorganic salts with fire and bioprotective properties: ammonium dihydrogen phosphate, magnesium sulfate heptahydrate, borax, surfactant and water in the following proportions, wt.%: Ammonium dihydrogen phosphate 11.0-12.0 , seven-water magnesium sulfate 23.0-25.0, borax 5.0-6.0, surfactant 1.0-1.5, water 55.0-60.0.

Solution for repeated (secondary) impregnation of 18.0-21.0% aqueous solution of calcium chloride (No. 2200088, B27K 3/52, publ. 10.03.2003).

The disadvantages of this method are its complexity, complexity, duration in the technological design, as well as the presence of energy consumption during its implementation.

An object of the present invention is a method for producing high-quality fire-resistant wood while reducing energy consumption, toxicity, laboriousness and duration of the production process, simplifying the technology and reducing the cost of the final product.

The technical result is achieved by the fact that in the method of fire-retardant treatment of wood, which is a temperature impregnation with an aqueous solution comprising a nitrogen-containing component and a drill, in contrast to the prototype, carbamide is used as the nitrogen-containing component, in the following ratio, wt.%:

Borax - 10-15

Urea - 10-15

Water - The rest,

and additionally introduced lime in an amount of 20-30% in relation to the amount of water.

First, a layer of lime is laid at the bottom of the tank, then a stack of wood is placed over it, then water is supplied, and borax and urea are added 20-30 minutes after the start of the reaction of water with lime.

The method involves saturating the wood with flavorings, by injecting the latter into a closed chamber with wood, at the rate of 1-2 g per 1 m ^{3 of} wood and holding it for 24 hours.

The method is implemented as follows.

A layer of quicklime (GOST 9179-77) is laid at the bottom of the tank at the rate of 230-240 kg per m ^{3 of} water, then a stack of wood mounted on a grid is installed above it.

The tank is closed with a lid and filled with water. As a result of the exothermic reaction between lime and water, the composition begins to boil:

CaO + H ₂ O-Ca (OH) ₂ +63.7 kJ / mol.

Lime reacts with water to form hydrated lime Ca (OH) ₂ . With the temperature and chemical effects of the solution on wood, all microflora in the vegetative stage is inactivated.

Then, after 20-30 minutes, for each m ^{3 of} water, the borax (GOST 8429-77) is supplied at a rate of 90-100 kg and urea (GOST 2081-92) is 90-100 kg. At a temperature of the impregnating solution of 100-60 ° C, the wood can withstand 60 minutes. Next, the stack is raised above the tank, and after the free solution has drained, the stack is moved to a drying warehouse.

The method involves saturating the wood with flavorings by injecting the latter into a closed chamber with wood at the rate of 1-2 g per 1 m ^{3 of} wood and holding it for 24 hours.

Using quicklime allows you to raise the temperature of the solution without using other energy sources and maintain the optimum temperature (100-60 ° C) throughout the saturation period, due to which the pores of the wood expand, the solution penetrates deeper into them, all harmful insects, their larvae and putrefactive microorganisms, and subsequently processed wood according to the proposed method, wood becomes an unacceptable material for them. Such material can be used in construction with a guarantee of a decade.

Experimentally, it was found the optimal amount of lime necessary to comply with the time and temperature conditions of wood processing, and it was found that borax has some inhibitory effect on the process of extinguishing lime and that an increase in the percentage of borax in the solution worsens the full course of the chemical reaction.

The data of the tests are shown in Table 1.

Table 1 The percentage of components in the solution Borax - 20%; Urea - 20%;
Water - ost. (Lime - 20.0% of the amount of water) Borax - 15%; Urea - 15%;
Water - ost. (Lime - 20% of the amount of water) t Borax - 10%; Urea - 10%;
Water - ost. (Lime - 20% of the amount of water) Borax - 5%; Urea - 5%;
Water - ost. (Lime - 20% of the amount of water) Borax - 3%; Urea - 3%;
Water-ost. (Lime - 20% of the amount of water) Bura-10% Urea ---;
Water - ost. (Lime - 20% of the amount of water) Bura; Urea - 10% -;
Water - ost. (Lime - 20.0% of the amount of water) Borax - 1.0-2.0%; Urea - 9.0-10%;
Water - ost. (Lime - 20% of the amount of water) Lime extinguishing reaction not leaking is leaking rapid flow rapid flow, low salt growth rapid flow, low salt growth rapid flow rapid flow rapid flow, low salt growth

To test the fire-bioprotective effectiveness of the proposed method for processing wood billets, tests were carried out for fire-retardant efficiency and resistance to biodegradation.

10 samples of pine wood were prepared in the form of rectangular bars with a cross section of 30 × 60 mm and a fiber length of 150 mm (according to GOST 16363-98) for impregnation according to the developed technology and testing for fire retardant efficiency.

Before the test, the processed and dried wood samples were conditioned under the conditions specified in 4.1.3, GOST 16363-98, and weighed with an error of not more than 0.1 g. A facility was installed to determine the fire-retardant effectiveness of coatings and impregnations according to GOST 16363-98.

The test results at an air temperature of 23 ° C and a relative humidity of 68% are presented in Table 2.

table 2 But-
sample measures Sample weight, g Consumption of the working staff Dry weight gain Sample weight loss The average weight loss of the samples before processing before burning after burning impregnating composition, kg / m ² dry flame retardant consumption, kg / m ² (g) (%) (g) (%) one 108 115 95.45 22 0.228 19.55 17 18.52 15.9 2 111 117 99.45 19 0.196 17.55 fifteen 3 110 117 98.28 19 0.228 18.72 16 four 109 116 98.6 22 0.228 17.40 fifteen 5 109 115 95.45 21 0.196 19.55 17 6 111 118 96.76 eighteen 0.228 21.24 eighteen 7 108 115 97.75 twenty 0.228 17.25 fifteen 8 110 118 99.12 twenty 0.261 18.88 16 9 110 118 100.3 19 0.261 17.70 fifteen 10 108 116 98.6 21 0.228 17.40 fifteen

According to the test results, a group of fire-retardant effectiveness of the tested impregnating composition is established with this method of its application, according to GOST 16363-98:

When the mass loss of the sample is not more than 9%, a group of fire-retardant efficiency is established for the wood protection product.

With a mass loss of more than 9%, but not more than 25%, a group of fire-retardant efficiency is established for wood protection products.

With a mass loss of more than 25%, it is believed that this product does not provide fire protection for wood.

The test results showed an average weight loss of samples equal to 15%, therefore, according to GOST 16363-98, wood treated by the proposed method, you can assign the 2nd group of fire-retardant efficiency.

The test samples, along with the control, not subjected to any processing, were tested for resistance to biodegradation, especially to rot caused by wood-decomposing fungi and microorganisms. The tests were carried out for 3 months. On pre-weighed wood samples with a size of 20 × 20 × 150 mm and a moisture content of 15%, placed in the flasks, a white house mushroom (Poria vaporaria) was applied and left in a dark place at room temperature.

The effectiveness of the test impregnation was carried out by the loss of samples of their mass, as decomposition by the fungus. The results obtained are presented in Table 3.

Table 3 No. p / p Pine core Pine sapwood Oak core Sapwood oak Pine core (counter.) Pine sapwood (counter) Oak core (counter) Oak sap. (counter) Infection of samples with porcini mushroom (3 months) one --- --- --- --- 2 --- - ++ --- --- 3 --- --- --- --- four --- - + --- --- 5 --- --- --- --- 6 - --- --- --- 7

Control (no processing) 1 (3 arr.) - ++ - ++ - + - + 2 (3 arr.) - ++ +++ - ++ - ++ 3 (3 arr.) - ++ - ++ --- - ++

As can be seen from Table 3, the test samples showed good ability to withstand wood-destroying fungi when tested for infection with porcini mushroom. So, at the end of the third month of the test, only single samples (2 pcs.) From the batch of samples (pine, sapwood) were subject to growth on the surface of the mycelium of the porcini mushroom.

In almost all, untreated, control samples, a weight loss of 68% to complete destruction was recorded.

The protective activity of the developed method was tested without fail against the fungus Coniophora puteana.

The effectiveness of the method is judged by the loss of wood mass. So, at a solution concentration (borax - 10-15%, urea - 10-15%, water - the rest; + lime - 20-30%), the weight loss of the wood was on average 2.83%. Based on this, the antiseptic properties of the proposed method in relation to the wood-destroying pine fungus Coniophora puteana can be considered quite effective.

The protection of samples processed by the new method against blue stain mushrooms was tested.

Evaluation of the effectiveness of the method was carried out after 5, 10 and 15 days of exposure on the average area of damage to the fungi of the surface of 3 groups of samples in%, which on the 15th day of testing turned out to be 10% in one of the three groups of impregnated wood samples, while how all groups of control samples were affected by 30-40% already on the 5th day of testing.

In addition, “field” tests of the samples were carried out according to the method recommended by the European standard EN 252 for determining the effectiveness of wood antiseptics. According to this technique, samples 500 × 50 × 25 mm in size were prepared, which were buried to a depth of 30 cm in the manmade soil of farmland. The results after six months of testing showed the following weight loss by the test samples as shown in Table 4:

Table 4 Test objects Mass loss in% Samples processed by the new method 2 (oak) - 6 (pine) Control (untreated) samples 11 (oak) - 48 (pine)

Studies have shown that the proposed method of fire-retardant treatment of wood provides it with the 2nd group of fire-retardant efficiency and optimal protection parameters from wood-destroying, wood-dying mushrooms and other pathogens, leading to damage and destruction of wood products.

Analysis of the entire series of tests allows us to consider the fire-retardant properties imparted to the wood blanks by the proposed method - a consequence of the experimentally found combination of composition components and special technological methods for introducing them into the processed wood.

Unlike the prototype, the method does not require:

- heating the impregnating composition, and uses the heat of the exothermic reaction of the interaction of lime with water;

- 2-3 hours of mixing the dissolving ingredients of the composition and the need to use 2 compositions, and is implemented in one go.

The method according to the present invention is efficient, fast, simple in technical design and cheap, provides the wood with the 2nd group of fire-retardant efficiency, destroys all the bio-forms present in the wood at the time of processing and protects against new infection. It improves quality by creating a uniform fire and bioprotective layer, which increases the service life of wood products.

The method can be easily implemented both in the factory and directly at the construction site.

Claims (3)

1. The method of fire-retardant treatment of wood, which is a temperature impregnation with an aqueous solution comprising a nitrogen-containing component and borax, characterized in that carbamide is used as the nitrogen-containing component, in the following ratio, wt.%:
Borax 10-15 Urea 10-15 Water Rest,
and additionally introduced lime in an amount of 20-30% in relation to the amount of water. 2. The method of fire-retardant treatment of wood according to claim 1, characterized in that at first a layer of lime is laid on the bottom of the tank, then a stack of wood is placed over it, then water is supplied, and borax and urea are added after 20-30 minutes, after the start of the water reaction with lime. 3. The method of fire-retardant treatment of wood according to claim 1, characterized in that it enriches the wood with flavorings by injecting the latter into a closed chamber with wood, at the rate of 1-2 g per 1 m ^{3 of} wood and holding it for 24 hours