KR102528138B1 - Processing method for improving dimensional stability, flame-resistance and proof against climate of exterior wood - Google Patents

Abstract

The present invention relates to a method for processing wood for exterior use to improve flame retardancy, dimensional stability and weather resistance. It is an exterior wood processing method that can be usefully used as an exterior material because it not only increases the durability of the flame retardant performance by improving the dimensional stability but also has the effect of enhancing the dimensional stability.

Description

Exterior wood processing method for improving flame retardancy, dimensional stability and weather resistance {Processing method for improving dimensional stability, flame-resistance and proof against climate of exterior wood}

The present invention relates to a method for processing wood for exterior use to improve flame retardancy, dimensional stability and weather resistance.

Wood, a natural polymeric compound, is lighter and stronger than other materials, is easy to process, exhibits various material properties with respect to temperature, humidity, sound, and electricity, and has a soft texture and beautiful appearance. It has been used as a material for various purposes.

However, in addition to these advantages, it has many defects such as rotting, burning, cracking, and twisting due to various causes during the use process, and thus has the disadvantage of losing its function as a material. In order to extend the useful life of wood by removing or supplementing various defects of wood, various wood preservation treatment chemicals and methods have been developed and used, and chemicals or treatment techniques can be classified according to the target of defects to be removed or supplemented. . Preservatives and preservative treatment technology to prevent wood rot (decay), insect repellent and insect repellent treatment technology to prevent insect damage, fire retardant (flame retardant, flame retardant) and fire prevention treatment technology to prevent combustion (fire), shrinkage and swelling It can be classified as a dimensional stabilizer and modification treatment technology to prevent distortion and cracking, and corresponds to wood preservative and preservation treatment technology in a broad sense. The most important element that wood preservatives (chemicals) used in processing to remove or supplement wood defects must have is that, in addition to the excellent effect acting on the defect factor, the active ingredients dissolve in moisture when exposed to precipitation during the use of preserved wood. It must have strong leaching resistance that does not elute to the outside. Active ingredients must have excellent resistance to leaching to moisture, but long-term effects can be guaranteed, and there are no restrictions on use as exterior materials such as structures directly exposed to precipitation or landscaping facilities. .

Among the wood preservatives, a fixative (adhesive) wood preservative (insect repellent) may be mentioned as a drug having excellent leaching resistance to moisture. After the active ingredients of these wood preservatives penetrate into the wood, they react with the wood chemical components inside and turn into insoluble compounds, so that even if exposed to precipitation, the problem of reducing the preservative (insect repellent) effect does not occur, ensuring a long service life of the treated wood. do.

In addition, with the spread of eco-friendly wooden houses, interest in the fire safety of wooden structures has increased, and the development of flame retardant chemicals for wood and the production of flame retardant wood are attracting attention. In order to reduce the combustibility of wood, various flame retardants have been developed and used in the manufacture of flame retardant wood, but all of these chemicals are water-soluble chemicals with no resistance to leaching to moisture, so they are not suitable for flame retardant treatment of wood used as an exterior material exposed to precipitation. and can only be used for interior wood treatment.

As a way to impart leaching resistance to moisture to flame retardant treated wood, a method and technique for developing a flame retardant (fixative or fixative flame retardant) of a poorly soluble compound that reacts with wood extract components to become insolubilized after penetrating into wood A method of preventing the leaching of the flame retardant component by water by using a water-soluble flame retardant that has been developed and used in combination with a water-insoluble (hydrophobic) compound can be considered.

The main elements constituting the flame retardant are phosphorus (P), boron (B), halogen elements (F, Cl, Br, I), etc., and fixable flame retardants centered on compounds composed of these elements have not yet been developed.

Meanwhile, Korean Patent No. 1230386 discloses a processing method for improving dimensional stability and flame retardancy of wood, Korean Patent No. 1390631 discloses a method for manufacturing flame retardant wood, and Korean Patent No. 0736211 discloses a paraffin layer formation. Although the method and apparatus are disclosed, the processing method of wood for exterior use to improve flame retardancy, dimensional stability and weather resistance of the present invention has not been disclosed yet.

The present invention has been derived from the above needs, and the present invention relates to a method for processing exterior wood for enhancing flame retardancy, dimensional stability and weather resistance. In addition to excellent stability and weather resistance, it was confirmed that water repellency was enhanced, and it was confirmed that nitrogen and phosphorus, which are flame retardant components included in the wood, remained even after weathering against water, thereby completing the present invention.

In order to achieve the above object, the present invention (1) after putting the exterior wood into the main tube, pressurized injection of a water-soluble flame retardant liquid;

(2) after the step (1), recovering the flame retardant liquid, depressurizing the inside of the main tube, going through a post exhaust process, and then recovering exterior wood into which the flame retardant liquid has been pressurized;

(3) after the above step (2), impregnating the exterior wood injected with the flame retardant liquid into the wax solution to replace moisture in the wood injected with the flame retardant liquid into wax; and

(4) after the step (3), wax-solidifying the exterior wood injected with the flame retardant and wax at room temperature; to improve flame retardancy, dimensional stability and weather resistance.

In addition, the present invention (1) after putting wood for exterior inside the main tube, a water-soluble flame retardant chemical solution containing at least one selected from boric acid, guanylurea phosphate and phosphoric acid Injecting under pressure for 3 to 6 hours under a pressure condition of 9 to 18 kgf/cm 2 ;

(2) after the above step (1), recovering the flame retardant liquid, reducing the pressure inside the main tube to 650 ~ 700 mmHg, going through a post exhaust process, and recovering exterior wood into which the flame retardant liquid has been pressurized injection;

(3) after the above step (2), impregnating the exterior wood into which the flame retardant liquid was pressurized into molten wax at a temperature of 70 to 105° C. to replace moisture with wax; and

(4) after the step (3), recovering the flame retardant and the wax-injected exterior wood and then solidifying the impregnated wax at room temperature; processing method is provided.

In addition, the present invention provides exterior wood with improved flame retardancy, dimensional stability and weather resistance by processing according to the processing method for exterior wood.

The present invention relates to a method for processing wood for exterior use to improve flame retardancy, dimensional stability and weather resistance. It is an exterior wood processing method that can be usefully used as an exterior material because it not only increases the durability of the flame retardant performance by improving the dimensional stability but also has the effect of enhancing the dimensional stability.

1 is a result of confirming the water repellency of wood manufactured according to the processing method of the present invention and wood treated with a flame retardant alone.
Figure 2 is a result of analyzing the elements contained in wood before weathering of flame retardant-treated wood, a is a photograph of the wood texture observed, and b is a spectrum of elements distributed in the observed tissue of a.
Figure 3 is a result of analyzing the elements contained in the wood after weathering of the wood treated with a flame retardant alone, a is a photograph of the wood tissue observed, and b is a spectrum of elements distributed in the observed tissue of a.
Figure 4 is a result of analyzing the elements contained in wood before weathering of wood according to the processing method of the present invention, a is a photograph of the observed wood structure, and b is a spectrum of elements distributed in the observed tissue of a .
5 is a result of analyzing the elements contained in wood after weathering of wood according to the processing method of the present invention, a is a photograph of the observed wood structure, and b is a spectrum of elements distributed in the observed tissue of a .

The present invention comprises the steps of (1) injecting a water-soluble flame retardant liquid under pressure after putting wood for exterior into the main tube;

(2) after the step (1), recovering the flame retardant liquid, depressurizing the inside of the main tube, going through a post exhaust process, and then recovering exterior wood into which the flame retardant liquid has been pressurized;

(3) after the above step (2), impregnating the exterior wood injected with the flame retardant liquid into the wax solution to replace moisture in the wood injected with the flame retardant liquid into wax; and

(4) after the step (3), wax solidifying the flame retardant and wax-infused exterior wood at room temperature; to improve flame retardancy, dimensional stability and weather resistance. It relates to a processing method for exterior wood.

In step (1), the water-soluble flame retardant liquid preferably contains at least one selected from boric acid, guanylurea phosphate, and phosphoric acid, but is not limited thereto.

In the step of pressurizing and injecting the water-soluble flame retardant chemical solution after putting the wood for exterior in step (1) into the main tube, after putting the wood for exterior in the main tube and sealing it, the pressure inside the main tube was adjusted to 650 ~ 700mmHg Then, after going through the entire exhaust process for 30 to 60 minutes, the flame retardant liquid is injected into the main tube, and the flame retardant liquid is pressurized into the wood for 3 to 6 hours under a pressure condition of 9 to 18 kgf/㎠ using a pressure pump. Injection is preferred, but not limited thereto.

In the step (2), the post-exhaustion is preferably performed by adjusting the pressure inside the main tube to 650 to 700 mmHg for 30 to 60 minutes, but is not limited thereto.

In the above step (3), the step of replacing the moisture inside the wood into which the flame retardant chemical solution is pressurized is replaced with wax by immersing the wood into which the flame retardant chemical solution is pressurized into molten wax at a temperature of 70 to 105 ° C. It is preferable to do so, but it is not limited thereto.

In addition, the present invention (1) after putting the wood for exterior inside the main tube, a water-soluble flame retardant chemical solution containing at least one selected from boric acid, guanylurea phosphate and phosphoric acid Injecting under pressure for 3 to 6 hours under a pressure condition of 9 to 18 kgf/cm 2 ;

(2) after the above step (1), recovering the flame retardant liquid, reducing the pressure inside the main tube to 650 ~ 700 mmHg, going through a post exhaust process, and recovering exterior wood into which the flame retardant liquid has been pressurized injection;

(3) after the above step (2), impregnating the exterior wood into which the flame retardant liquid was pressurized into molten wax at a temperature of 70 to 105° C. to replace moisture with wax; and

(4) after the step (3), recovering the flame retardant and the wax-injected exterior wood and then solidifying the impregnated wax at room temperature; processing method is provided.

In addition, the present invention provides exterior wood with improved flame retardancy, dimensional stability and weather resistance by processing according to the processing method for exterior wood.

In the present invention, the pressure treatment refers to a method of injecting a wood preservative into wood by putting wood into a sealed main container and applying pressure and pressure through a pump based on the pressurized preservative treatment method of wood.

The former exhaust treatment refers to the exhaust treatment for the purpose of extracting air from the wood and deeply infiltrating the working fluid in a large amount in the injection treatment, and the latter exhaust treatment is to extract the excess working fluid from the inside of the wood after the pressurization process of the pressure treatment is completed. It means the target exhaust treatment.

Hereinafter, the present invention will be described in more detail using examples. These examples are only for explaining the present invention in more detail, and it is obvious to those skilled in the art that the scope of the present invention is not limited thereto.

Example 1. Flame retardant treatment and paraffin wax treatment of wood

(1) Wood flame retardant treatment (step 1): pressurized injection (fill cell method) process

① Put the treated wood into the main chemical pipe and seal it → ② Depressurize the inside of the main chemical pipe and exhaust it (650~700mmHg, 30~60 minutes) → ③ Inject flame retardant chemical solution into the main chemical pipe (fill the inside of the main chemical pipe with chemical solution) → ④ Pressurize and push the chemical liquid into the wood using a pressurized pump (Pressure force 9~18kg/㎠, 3~6 hours) → ⑤ Pressurization stop → ⑥ Recover the chemical liquid → ⑦ Depressurize the inside of the main chemical pipe and exhaust (650~700mmHg, 30~60 minutes) → ⑧ Recovery of wood pressurized with flame retardant liquid

(2) Paraffin Wax Treatment (Step 2): Heating-Decompression-Pressure Process

① The flame-retardant chemical injection wood treated in step 1 was immersed in a molten wax bath installed in the main tube and sealed. At this time, the wood was fixed so that it would not float on the surface of the wax solution due to buoyancy.

② The temperature of the molten wax in which the wood was immersed was maintained at 70 to 105 ° C by heating for 24 hours. The wood into which the flame retardant liquid is injected is heated by the wax solution to evaporate moisture inside the wood and fill the inside of the main tube with steam. Therefore, the vapor was discharged by weakly reducing the pressure every 2 to 3 hours. In this process, the active ingredient of the flame retardant liquid is not evaporated, only moisture is evaporated, and replaced with a wax solution. Therefore, this process is a process in which the wax injection is performed simultaneously with the drying of the flame retardant treated wood.

③ The inside of the main tube was decompressed (650-700mmHg, 30-60 minutes) in order to completely remove the remaining moisture inside the wood and inject the wax solution into the cell lumen inside the wood.

④ Stop depressurization and return the inside of the main cylinder to normal pressure (atmospheric pressure).

⑤ Pressurize the inside of the main tube using compressed gas (pressurization force 9~18kg/㎠, 3~6 hours): The flame retardant active ingredient remaining inside the treated wood (cell lumen and cell wall) is completely coated with wax to prevent moisture loss. It is a dimensional stabilization treatment process by volume treatment that prevents contact and at the same time prevents dissolution, and prevents shrinkage or swelling by filling the empty space (cell lumen or gap) inside the cell with wax solution.

⑥ Pressure stopped.

⑦ Wood injected with flame retardant and wax solution was recovered.

⑧ The wax was solidified at room temperature.

Example 2. Flame retardant performance, dimensional stability and water repellency evaluation

A test specimen of yellow-leaved tree (tulip), a broad-leaved tree expected to be expanded in the future as a domestic attribute tree, was produced, and it is registered as a flame retardant for wood with the American Wood Protection Association (AWPA), and it has been shown to have excellent wood flame retardant performance. A known product, Dricon (manufacturer: Lonza), was used as a flame retardant. The flame retardant is composed of three components: boric acid, guanylurea phosphate and phosphoric acid.

(1) Difference in flame retardant performance

For untreated and each treated specimen, the average ignition time and weight loss rate were measured and compared using TCA (Thermal Characteristic Analyzer, a type of Cone Calorimeter Method).

In order to compare the difference in water leaching properties of the active ingredients of the flame retardant, a weathering operation (forcibly exposed to water to test the water leaching resistance of the wood flame retardant) was performed. Specifically, after immersing in tap water at room temperature 10 times the volume of the test specimen while stirring for 24 hours, drying in hot air (60 ° C) for 24 hours was performed twice.

Table 1 shows the difference in flame retardant performance (average weight loss due to ignition time and combustion) for each treatment method.

Changes in flame retardant performance before and after weathering of each treated timber processing method average ignition time
(candle) by combustion
Average Weight Loss (%) Before weathering After weathering Before weathering After weathering untreated 19.7 12.7 40.8 52.4 flame retardant alone
process 89.3 11.3 25.7 40.2 paraffin wax
exclusive processing 12.3 11.8 36.8 37.2 Processing of the present invention
(Flame Retardant - Paraffin Wax) 19.0 13.1 23.5 29.9

Comparing the average ignition time before weathering, the wood treated with paraffin wax alone caught fire the fastest, and the wood treated only with flame retardant caught fire last. Wood treated with the processing method of the present invention showed ignition later than paraffin wax treatment alone and faster than flame retardant treatment alone, which was similar to the ignition level of untreated wood.

After weathering, the ignition time of all treated woods was very short, showing a phenomenon in which the fire caught fire quickly. In particular, wood treated with flame retardant alone tended to have a very short ignition time because all active ingredients exhibiting flame retardant performance were leached by weathering operation.

Wood treated with the processing method of the present invention also tended to catch fire quickly due to weathering, but caught fire relatively late compared to other treated wood. This result was determined to be due to suppression of dissolution of the flame retardant component by post-treatment of the paraffin wax.

Comparing the difference in weight loss due to combustion, the untreated wood showed the greatest difference both before and after weathering, and the wood treated with only paraffin wax showed no significant difference before and after weathering.

The wood treated with flame retardant alone showed a very small weight loss before weathering, but showed a rapid weight loss after weathering because all flame retardant components were leached. The wood treated with the processing method of the present invention showed the smallest weight loss even before weathering, and even after weathering, a small weight loss occurred compared to other treated wood. It was judged to have contributed to the expression.

The wood treated with paraffin wax alone tended to catch fire easily due to the short ignition time, but the reason why the weight loss due to combustion was smaller than that of the untreated wood was that the burning of the wood substance was caused by the heat absorbing action of the paraffin wax injected into the treated wood. It was judged to be due to delay.

<Comparison of flame retardant performance>

Before weathering treatment: flame retardant treatment alone > combined treatment (invention) > paraffin wax treatment alone > no treatment

After weathering: Combined treatment (invention) > Paraffin wax treatment alone > Flame retardant treatment alone > No treatment

(2) Comparison of dimensional stability

The volume water absorption rate and volume swelling rate were investigated and compared for each treatment method.

As a result, as shown in Table 2, it was confirmed that the dimensional stability of the wood treated with the processing method of the present invention was smaller than that of paraffin-only treated wood, but the water absorption rate and swelling rate were lower than untreated and flame retardant-treated wood.

Dimensional stability of each treated lumber processing conditions Dimensional stability Volume absorption rate (%) Volume swelling rate (%) untreated 74.1 15.6 Flame retardant treatment alone 64.6 13.0 Paraffin wax treatment alone 8.2 8.0 invention technology processing
(Flame Retardant - Paraffin Wax) 23.8 11.0

(3) Difference in water repellency (contact angle of water droplets)

As a result of confirming the contact angle of water droplets for each treatment condition, as shown in Table 3 and FIG. 1, the wood treated with the processing method of the present invention has a very large contact angle of water droplets compared to untreated and flame retardant alone treatment, and paraffin wax alone treatment wood It was found that the water repellency was superior to that of This means that the water wettability is very low and the dimensional stability is excellent.

Water droplet contact angle of each treated wood processing conditions water droplet contact angle Right (°) left (°) Average (°) untreated 66.0 66.0 66.0 Flame retardant treatment alone 34.3 34.2 34.3 Paraffin wax treatment alone 96.7 96.6 96.7 invention technology processing
(Flame Retardant - Paraffin Wax) 103.6 104.0 103.8

Example 3. Checking the distribution state of the constituent elements (nitrogen and phosphorus) of the flame retardant in wood

Using a scanning electron microscope (SEM) and an energy dispersive characteristic X-ray analyzer (EDS), changes in the distribution of active components of the flame retardant before and after weathering were analyzed in the wood treated with the flame retardant alone and the wood treated with the processing method of the present invention.

① Distribution of flame retardant elements (N and P) before weathering of wood treated with flame retardant alone

Characteristic X-ray spectra of phosphorus (P) and nitrogen (N), which are constituent elements of the used flame retardant, were detected, although insignificant. Here, carbon and oxygen represent constituent elements of wood, which is an organic material, and are elements detected regardless of flame retardant treatment. Among the detected elements, the proportions of N and P, which are components of the flame retardant, were 0.86wt% and 0.44wt%, respectively, which means that the flame retardant was distributed in the wood before weathering.

② Distribution of flame retardant elements (N and P) after weathering of wood treated with flame retardant alone

Looking at the ratio of constituent elements in the wood tissue subjected to weathering after treatment with flame retardant alone, N and P, which were present in the treated wood tissue before weathering, were not detected at all (both N and P were 0.00 wt%). From these results, it was confirmed that all the flame retardants were leached by moisture during weathering, and that the wood flame retardant had no resistance to leaching (weather resistance) to moisture at all (FIG. 3).

③ Distribution of elements (N and P) of the flame retardant before weathering of wood treated with the processing method of the present invention (flame retardant-paraffin wax)

The distribution of flame retardant components was confirmed before weathering in the structure of the wood treated by the processing method of the present invention (N: 1.53wt%, P: 0.66wt%).

As a result, it was confirmed that wax was filled in the cell lumen of the conduit and the wood fiber in the tissue observation secondary electron image of FIG. 4 (a).

④ Distribution of flame retardant elements (N and P) after weathering of wood treated with the processing method of the present invention (flame retardant-paraffin wax)

The distribution of the flame retardant component was confirmed after weathering in the structure of the wood treated by the processing method of the present invention (N: 0.05wt%, P: 0.49wt%).

As a result, as shown in FIG. 5, it was confirmed that the wax filled in the cell lumen of the conduit and the wood fiber was still present in the tissue observation secondary electron image of a even after weathering. Unlike in the wood treated with the flame retardant alone, it was confirmed that even after weathering treatment, the ratio of constituent elements of the active ingredient of the flame retardant decreased in the observed tissue of the treated wood, but remained.

It can be judged that this is the result of suppressing moisture penetration into the wood tissue and leaching of active ingredients by moisture as the wood cell walls and cell lumen penetrated with the flame retardant active ingredient are filled with the hydrophobic paraffin wax treated subsequent to the flame retardant treatment. there is.

Claims (7)

(1) After putting the exterior wood into the main cylinder and sealing it, adjust the pressure inside the main cylinder to 650 ~ 700mmHg, and then go through the exhausting process for 30 ~ 60 minutes, and then pour the flame retardant chemical into the main cylinder. and injecting a flame retardant liquid into the wood for 3 to 6 hours at a pressure of 9 to 18 kgf/cm 2 using a pressure pump;
(2) After the step (1), the flame retardant liquid is recovered, the inside of the main tube is depressurized to 650 to 700 mmHg for 30 to 60 minutes, and then the flame retardant liquid is pressure-injected. step;
(3) After the step (2), the exterior wood into which the flame retardant chemical solution recovered in the step (1) is pressure-injected is immersed in a molten wax bath installed in the main cylinder, heated to 70 to 105 ° C, and present inside the wood. In order to evaporate moisture without evaporating the flame retardant component, the pressure is periodically reduced for 2 to 3 hours to discharge steam, and then the inside of the main tube is reduced to 650 to 700 mmHg for 30 to 60 minutes to penetrate the cell lumen inside the wood. Infiltrating wax into; and
(4) after the step (3), recovering the exterior wood into which the flame retardant and wax are injected, and then solidifying the wax impregnated inside the wood at room temperature; to improve flame retardancy, dimensional stability and weather resistance, including A method for processing wood for exterior use. The exterior wood according to claim 1, characterized in that in the step (1), the water-soluble flame retardant liquid contains at least one selected from boric acid, guanylurea phosphate and phosphoric acid. processing method. delete delete delete (1) After putting wood for exterior inside the main tube, a water-soluble flame retardant chemical solution containing at least one selected from boric acid, guanylurea phosphate, and phosphoric acid is applied at 9 to 18 kgf / cm 2 Injecting under pressure for 3 to 6 hours under a pressure condition of;
(2) after the above step (1), recovering the flame retardant liquid, reducing the pressure inside the main tube to 650 ~ 700 mmHg, going through a post exhaust process, and recovering exterior wood into which the flame retardant liquid has been pressurized injection;
(3) after the above step (2), impregnating the exterior wood into which the flame retardant liquid was pressurized into molten wax at a temperature of 70 to 105° C. to replace moisture with wax; and
(4) after the step (3), recovering the flame retardant and the wax-injected exterior wood and then solidifying the impregnated wax at room temperature; processing method. Exterior wood with improved flame retardancy, dimensional stability and weather resistance by processing according to the processing method of any one of the exterior wood processing methods selected from claims 1, 2 and 6.

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