WO2020054838A1 - Method for producing noncombustible material, and noncombustible material - Google Patents

Abstract

[Problem] To ensure the noncombustibility of a noncombustible material by boric acid alone without adding an additive to promote the dissolution of boric acid. [Solution] First, an object 2 to be treated, which serves as the main material of a noncombustible material, is placed in an impregnation tank 1 in which is stored a boric acid aqueous solution. The boric acid aqueous solution is a solution of boric acid dissolved in water without adding an additive to promote the dissolution of boric acid in water. Next, the boric acid introduced into the impregnation tank 1 is furthermore dissolved while raising the temperature of the boric acid aqueous solution under a pressurized environment, whereby the concentration of the boric acid aqueous solution with which the object 2 to be treated is to be impregnated is made higher than the maximum solubility under an atmospheric-pressure environment. Then, the temperature of boric acid aqueous solution, the concentration of which has been raised, is reduced under conditions that maintain a pressurized state at least until the temperature drops to the boiling point under an atmospheric-pressure environment, thereby precipitating the boric acid with which the object 2 to be treated is impregnated.

Description

Method for producing noncombustible material and noncombustible material

The present invention relates to a method for producing a non-combustible material and a non-combustible material, and more particularly to non-combustible material using boric acid.

Conventionally, water-soluble inorganic salts such as boric acid, borax, phosphoric acid, ammonium salt of strong acid, and sodium silicate have been known as one of fire retardants added to incombustible wood used for building applications. Regarding this inorganic salt, Non-Patent Document 1 generally states that when performing a fire protection treatment using an inorganic salt, it is difficult to obtain a sufficient fire protection effect with a single agent, and two or more types of agents may be mixed and used. Many points are pointed out. Also, it has been pointed out that boric acid and borax are difficult to use as fire retardants because they have a low fire-protection effect and low solubility when used alone. However, it is pointed out that the use of a mixture of both eliminates the disadvantages.

Patent Document 1 discloses that boric acid and borax are contained in an amount exceeding the solubility of a single compound at 40 to 100 ° C., and x part of boric acid and y part of borax (provided that (x ≧ 35, y ≧ 40) is disclosed as a stable boron compound liquid composition containing 8.3 mol / kg or more in terms of boron. Patent Document 2 discloses a wood-based noncombustible chemical in which a phosphoric acid-based noncombustible chemical, which is an organic phosphate containing nitrogen, is dissolved in an aqueous solution of an ammonium chemical that is gasified by heating to a solubility equal to or higher than a single solubility. It has been disclosed.

Japanese Patent No. 50799983 Japanese Patent No. 4444991

As pointed out in Non-Patent Document 1 described above, boric acid alone has a weak fire-protection effect and a low solubility, so that it is difficult to use it as a fire-retardant, and boric acid is added to promote the dissolution of boric acid. It was a general recognition in the art that an object (such as borax) should be added. However, since borax or the like has deliquescence (hygroscopicity), there is a problem that this causes whitening of the material to be treated and water dripping due to the appearance of water droplets. In addition, as described in Patent Document 2, when an ammonia-based chemical is used, there is a problem that an ammonia odor is generated. When an attempt is made to remove the ammonia odor, a drying process is performed for a longer time than usual to promote thermal decomposition. Therefore, another problem such as an increase in manufacturing cost occurs.

The present invention has been made in view of such circumstances, and an object of the present invention is to ensure the non-combustibility of a non-combustible material using boric acid alone without adding an additive for promoting dissolution of boric acid. It is.

べ く In order to solve such a problem, a first invention provides a method for producing a noncombustible material having a charging step, a high concentration step, and a precipitation step. In the charging step, a boric acid aqueous solution in which boric acid is dissolved and an object to be treated as a main material of a non-combustible material are charged into the impregnation tank without adding an additive for promoting dissolution of boric acid. In the concentration step, the boric acid aqueous solution to be impregnated inside the object to be treated is dissolved in the atmospheric pressure environment by further dissolving the boric acid introduced into the impregnation tank while raising the temperature of the boric acid aqueous solution under a pressurized environment. The concentration becomes higher than the solubility below. In the precipitation step, the boric acid impregnated inside the object to be treated is lowered by lowering the temperature of the aqueous solution of boric acid with a high concentration, on condition that the pressurized state is maintained at least until the temperature drops to the boiling point under the atmospheric pressure environment. Precipitate.

Here, in the first invention, in the concentration increasing step, the temperature of the boric acid aqueous solution is preferably set to 120 ° C. or higher, and a more preferable range is 140 to 160 ° C. Further, the concentration increasing step is to increase the concentration of the boric acid aqueous solution by dissolving boric acid as a solid substance that has not completely dissolved and is precipitated in the immersion tank, with the temperature rise of the boric acid aqueous solution. Is also good. In addition, prior to the concentration increasing step, an impregnation tank into which the processing target is charged is placed under a vacuum environment to further provide an air removing step for removing air contained in the processing target. Is also good. Further, in the precipitation step, the boric acid aqueous solution may be cooled by heat exchange with a cooling liquid.

The second invention provides a non-combustible material containing boric acid, containing no additive for promoting the dissolution of boric acid in water, and having a boric acid content of 180 kg / m ³ or more.

The third invention contains boric acid, does not contain an additive for promoting the dissolution of boric acid in water, and has a total calorific value of 8 MJ when heated for 20 minutes in a heat generation test using a corn calorimeter. / M ² or less.

According to the first aspect, the temperature of the boric acid aqueous solution is increased in a pressurized environment. Since the solubility of boric acid increases as the temperature increases, it has a high temperature dependency, so if the temperature of a boric acid aqueous solution is raised under a pressurized environment, the addition of boric acid to promote the dissolution of boric acid in water will occur. A large amount of boric acid can be dissolved in water without adding a substance. This increases the amount of boric acid deposited inside the object to be treated, so that a noncombustible material having excellent noncombustibility can be obtained. Further, according to the second and third inventions, nonflammability in conformity with legal standards can be ensured, and an additive having a deliquescent (hygroscopicity) such as borax is not included. Water dripping due to whitening and the appearance of water droplets can be prevented.

Explanatory drawing of the input process of the processing object Explanatory drawing of the air removal process from the processing object Illustration of the heating process under atmospheric pressure environment Illustration of the process for increasing the concentration of a boric acid aqueous solution under a pressurized environment Illustration of boric acid precipitation process Characteristics table for each test piece by exothermic test with corn calorimeter

不 The non-combustible material according to the present embodiment is used for architectural purposes, and the goal is to obtain performance certification in accordance with the Building Standards Act of Japan (exothermic test). The feature of this incombustible material is that boric acid alone as a fire retardant ensures sufficient fire protection performance without using an additive such as borax added to promote dissolution of boric acid. . Hereinafter, a method for manufacturing a noncombustible material will be described with reference to FIGS. 1 to 5.

{Circle over (1)} First, as shown in FIG. 1, the boric acid aqueous solution and the object to be treated 2 are charged into the impregnation tank 1. The boric acid aqueous solution is a mixture of water and boric acid without adding an additive for promoting the dissolution of boric acid in water. The amount of boric acid charged into the impregnation tank 1 is 67 g / 100 ml or more, and the solid remaining without being dissolved in water is precipitated at the bottom of the impregnation tank 1. Generally, additives for promoting the dissolution of boric acid in water include, but are not limited to, borax, phosphoric acid, and ammonium salts. The boric acid solid remains to dissolve more boric acid in the subsequent process. The processing object 2 is a main material of non-combustible material, and is typically a general wood (solid material), a compressed material, a laminated material, a plywood, an oriented strand board (OSB), a particle board. , Laminated Veneer Lumber (LVL), Parallel Strand Lumber (PSL), Oriented Strand Lumber (OSL), Medium Density Fiberboard (MDF), etc. In addition, bamboo, grass, paper, cardboard and the like may be used. A weight 3 is placed on the upper part of the processing object 2 so as not to float from the liquid.

(2) Next, as shown in FIG. 2, the impregnation tank 1 into which the object to be treated 2 is charged is placed under a vacuum pressure environment, that is, a space state in which the pressure is lower than the atmospheric pressure. Specifically, first, the impregnation tank 1 is accommodated in the closed tank 4. Next, the pressure in the closed vessel 4 is reduced to a predetermined pressure, and this state is maintained for a predetermined time (for example, about 60 minutes). Thereby, the air contained in the processing target object 2 is discharged to the outside. The reason for providing this step is to remove fine air present in the fibers of the processing target object 2 in the fibers of the processing object 2 and thereby impregnate the boric acid aqueous solution, thereby promoting the impregnation of the boric acid aqueous solution in the subsequent step. is there. In addition, even if this step is not performed, this step may be omitted as long as a sufficient impregnation amount of the boric acid aqueous solution can be secured.

Next, as shown in FIG. 3, after taking out the impregnating tank 1 from the closed tank 4, by heating the bottom of the impregnating tank 1 under the atmospheric pressure environment, the boric acid aqueous solution is heated to about 100 ° C. . As a result, boric acid (shown by hatching) as a precipitate introduced into the impregnation tank 1 in the previous charging step dissolves, and the concentration of the boric acid aqueous solution increases as the temperature increases. The reason for providing this step is to shorten the processing time in the next step under a pressurized environment by increasing the concentration of the boric acid aqueous solution to a certain level.

Next, as shown in FIG. 4, the impregnation tank 1 is heated in a pressurized environment with high-temperature steam, and the temperature of the boric acid aqueous solution is raised to a predetermined temperature, for example, a temperature higher than 100 ° C. The solubility of boric acid in water increases as the water temperature rises to 70 ° C. or higher. By heating in a pressurized environment, boric acid as a precipitate introduced into the impregnation tank 1 in the previous charging step is further dissolved, and the boric acid aqueous solution to be impregnated inside the object 2 is treated under atmospheric pressure. The concentration is higher than the lower maximum solubility. When the atmospheric pressure is the standard atmospheric pressure (1 atm), the maximum solubility of the boric acid aqueous solution is a solubility at a boiling point of 100 ° C., for example, a concentration obtained by dissolving 40.25 g of boric acid in 100 g of water.

高温 As a device used in this step, a high-temperature high-pressure vessel is used as the high-pressure tank 5. The high-temperature and high-pressure container is a device that raises and heats the internal temperature with high-temperature steam of 100 ° C. or more, and the temperature is adjusted by pressurizing saturated steam. For example, the pressure in the high-pressure tank is 0.196 MPa at 120 ° C., 0.36 Mpa at 140 ° C., and 0.618 Mpa at 160 ° C. As a specific processing content of this step, first, the impregnation tank 1 is accommodated in the high-pressure tank 5. Next, the inside of the high-pressure tank 5 is pressurized by high-temperature steam to about 0.4 to 0.6 MPa (4 to 6 atm). For example, when the temperature of the steam is 140 ° C., the pressure is increased to 0.4 MPa, when the temperature is 160 ° C., the pressure is increased to 0.6 MPa, and the temperature of the impregnation tank 1 in the high-pressure tank 5 is also increased to the same extent. This state is maintained for a predetermined time (for example, 3 to 6 hours). As a result, the solid of boric acid precipitated in the impregnation tank 1 is further dissolved, and the solubility of the boric acid aqueous solution is also increased under the atmospheric pressure environment. In the present embodiment, the temperature of the boric acid aqueous solution is set to 120 ° C. or higher, more preferably 140 to 160 ° C. It should be noted that the pressurization in this step can promote the impregnation of the treatment object 2 with the concentrated boric acid aqueous solution (impregnation promoting effect).

水 The water temperature of the boric acid aqueous solution is maintained at the set temperature by pressurizing with high-temperature steam. Since the temperature of the water vapor around the impregnation tank 1 is maintained at this temperature, if the temperature of the impregnation tank 1 reaches, for example, 140 ° C., the temperature changes to 140 ° C. as it is. The water temperature can be measured, for example, by placing a temperature sensor in the high-pressure tank 5 and immersing it in an aqueous boric acid solution.

{Circle around (2)} After a predetermined time has elapsed, the temperature of the high-pressure tank 5 is lowered, and the concentration of the boric acid solution is lowered, whereby boric acid impregnated inside the processing object 2 is precipitated. In this temperature decreasing process, the pressurized state is maintained at least until the temperature falls to the boiling point under the atmospheric pressure environment. The reason for maintaining the pressurized state is as follows. First, it is to prevent evaporation of water in the boric acid aqueous solution. When the pressure in the high-pressure tank 5 is returned to normal pressure in order to take out the impregnating tank 1 at a high temperature, the boric acid aqueous solution exceeds 100 ° C. at that point, so that it boils at a stretch and evaporates. Second, the reduction of the boric acid content contained in the processing target object 2 is minimized. When the pressure is rapidly decreased, the boric acid aqueous solution boils, and a large amount of boric acid that has penetrated into the processing target object 2 is released to the outside. Third, it is to prevent the water surface of the boric acid aqueous solution from lowering and to prevent the processing target 2 from being exposed.

(5) After that, when the internal temperature has reached about 90 ° C. after about 1.5 hours, or when the internal temperature has reached room temperature, the pressurization in the high-pressure tank 5 is stopped. Then, when the internal pressure becomes 0.6 MPa or less and the internal temperature becomes about 70 ° C. after a predetermined time elapses, or when the internal temperature becomes room temperature, the pressure in the high-pressure tank 5 is gradually reduced. Thereafter, when the internal pressure becomes 0.2MP or less, the valve 5a is opened to return the internal pressure to the atmospheric pressure, and then the impregnation tank 1 is taken out of the high-pressure tank 5. At this time, the temperature of the boric acid aqueous solution is about 90 ° C. or room temperature.

(5) Finally, as shown in FIG. 5, the temperature of the concentrated boric acid aqueous solution is gradually lowered under the atmospheric pressure environment. Specifically, the impregnation tank 1 taken out of the high-pressure tank 5 is immersed in a cooling liquid tank 6 storing a cooling liquid (for example, water). Thereby, the boric acid aqueous solution is cooled by heat exchange with the cooling liquid. Alternatively, it is cooled to room temperature while maintaining the pressurized state. As a result, as the cooling gradually progresses, boric acid impregnated inside the processing object 2 gradually precipitates as a solid.

Thereafter, after the temperature is brought to room temperature, the processing object 2 is taken out of the impregnation tank 1, and the non-combustible material is completed through a drying step and the like. The non-combustible material produced through the above series of treatments has, as its characteristics, first, boric acid and no additives for promoting dissolution of boric acid in water. . Second, the boric acid in the non-combustible material exists almost uniformly throughout the inside as compared with a method of spraying boric acid from the outside.

FIG. 6 is a characteristic table for each test piece in a heat generation test (when heated for 20 minutes) using a corn calorimeter. The exothermic test using a corn calorimeter is based on ISO5660 used in Japan for the fire performance test of the new Building Standard Law enforced from June 2001 in Japan. In order to receive national accreditation, it must clear the standards of this test.

試 験 The test results shown in the table show the characteristics of twelve test pieces. As a test body, cedar wood, which is one of the processing objects 2, is used. As the test conditions, initially, the weight percentage of water and boric acid (the weight percentage of boric acid including boric acid and insoluble boric acid with respect to the total weight of boric acid and water) charged into the impregnation tank 1 is 40% or 50%. The heating temperature in a pressurized environment is 150 ° C. (sample numbers 1-2) and 160 ° C. (sample numbers 3-12). The content of boric acid in the noncombustible material is measured as follows. First, a plurality of samples of the same size are extracted from a cedar material (base material), a sample having a median weight is prepared as an untreated sample, and the other samples are used for impregnation. The dimensions of the sample are 100 mm * 100 mm * 50 mm. Next, both the impregnated sample and the untreated sample are subjected to a drying treatment, and then the absolute dry weight is measured. Then, the value obtained by subtracting the absolute dry weight of the untreated sample from the absolute dry weight of each impregnated sample is defined as the boric acid content. Here, the “absolute dry weight” refers to the weight at the time when the weight is completely changed (for example, 24 hours) in the dryer and the weight no longer changes.

Generally, when the amount of boric acid impregnated into wood, including the case where an additive is contained, exceeds about 200 kg / m ^3, the total calorific value in the exothermic test (when heated for 20 minutes) is less than 8 MJ / m ² . It is said that. According to the present embodiment, even without using an additive for accelerating the dissolution of boric acid in water, the boric acid content is 180 kg / m ³ or more, and / or an exothermic test using a corn calorimeter. And a total calorific value during heating for 20 minutes of 8 MJ / m ² or less can be realized. As shown in the table, all of the specimens Nos. 1 to 12 had a boric acid content of 188 kg / m ³ or more and a total calorific value of 8 MJ / m ² or less. Effectively satisfies the certification criteria for non-combustible materials based on the law (exothermic test).

In addition, although the above experimental results are obtained by using cedar wood as a sample, it is expected that the desired non-combustibility of cypress is also obtained. Also, it is considered that effective non-combustible performance can be obtained for wood having a lower specific gravity than cedar, such as falkata, paulownia, balsa, white wood close to cedar, white pine, hiba, and spruce.

In the present embodiment, the impregnation tank 1, the closed tank 4 and the high-pressure tank 5 are separately used, but it is not indispensable to divide these three tanks, and one or two tanks may have the same function. .

As described above, according to this embodiment, the temperature of the boric acid aqueous solution is raised to a temperature higher than 100 ° C. in a pressurized environment. Since the solubility of boric acid has a high temperature dependency, which increases as the temperature increases, a large amount of boric acid can be dissolved in water by raising the temperature of a boric acid aqueous solution under a pressurized environment. Conventionally, boric acid alone has a weak fire-protection effect and has a low solubility, so it is difficult to use it as a fire-retardant.In order to promote the dissolution of boric acid, borax, phosphoric acid, and additives such as ammonium salts are used. However, in the present embodiment, the dissolution of boric acid is promoted by heating under a pressurized environment. By increasing the concentration of the boric acid aqueous solution under a pressurized environment, the amount of boric acid deposited inside the object to be treated 2 can be increased, so that the incombustibility of the noncombustible material conforming to the Building Standards Law (exothermic test) Can be secured.

In the present embodiment, boric acid exceeding the maximum solubility of boric acid at the standard atmospheric pressure (1 atm) is charged into the impregnation tank 1 in the charging step in advance (at this time, a part of boric acid is dissolved. However, it is precipitated as a solid without being dissolved), and is further dissolved in the concentration increasing step. However, the present invention is not limited to such a procedure, and the timing at which boric acid is introduced into the impregnation tank 1 may be performed in parallel with the temperature increase in the concentration increasing step, or May be performed alternately with the temperature rise.

Further, according to the present embodiment, basically, it is possible to impregnate the treatment object 2 only with inexpensive boric acid, and it is not necessary to synthesize an expensive non-combustible chemical. Can be manufactured. In addition, boric acid itself is a substance used to wash eyes in the past, and does not harm the human body unless taken in large quantities. Therefore, it can be said that the noncombustible material of boric acid alone has high safety for the human body.

According to the present embodiment, since there is no deliquescent (hygroscopic) additive such as borax, it is possible to prevent whitening of the incombustible material and water dripping due to the appearance of water droplets due to this. Deliquescence refers to a phenomenon in which a substance takes in water (water vapor) in the air and spontaneously turns into an aqueous solution. Liquefaction occurs when there is a small volume of saturated aqueous solution on the crystal surface and its saturated vapor pressure is less than atmospheric water vapor pressure. Water vapor in the atmosphere is taken into the surface of the saturated aqueous solution, and the saturated aqueous solution is diluted. However, the amount of substance of the crystal is sufficiently large, and even if some water dissolves the crystal, the crystal is not completely dissolved. Thus, the volume of the saturated aqueous solution continues to increase, eventually dissolving all the crystals, and then diminishing until the water vapor pressure of the aqueous solution equals the water vapor pressure in the atmosphere. Then, further absorption of water stops. Due to this deliquescence, the noncombustible material absorbs water, and a phenomenon in which they drip (misunderstanding as dew condensation) or water in which boric acid in the processing object 2 is dissolved appears on the surface, and becomes white when the water dries. It causes the whitening phenomenon. This is a major hindrance to the use of non-combustible materials, and causes the problem that glue cannot be formed because the strength of the adhesive does not appear. Not including a deliquescent substance as a noncombustible material is extremely effective in promoting the use of the noncombustible material and in ensuring the adhesive strength of the laminated wood.

物質 Among substances having a deliquescent property, as a substance that increases the solubility of boric acid, secondary ammonium phosphate, borax (sodium tetraborate decahydrate), and ammonium hydrogen carbonate are known. In addition, phosphoric acid is one that may increase the solubility of boric acid, and tinboa (disodium octaborate tetrahydrate) is one that mainly contains boric acid.

DESCRIPTION OF SYMBOLS 1 Impregnation tank 2 Processing object 3 Weight 4 Sealed tank 5 High pressure tank 6 Coolant tank

Claims (8)

1. In the method of manufacturing a noncombustible material,
   Without adding an additive for promoting the dissolution of boric acid, a boric acid aqueous solution in which boric acid is dissolved, and a charging step of charging a treatment target serving as a main material of a non-combustible material into an impregnation tank,
   By raising the temperature of the boric acid aqueous solution under a pressurized environment and further dissolving the boric acid introduced into the impregnation tank, the boric acid aqueous solution to be impregnated inside the object to be treated is higher than the maximum solubility under the atmospheric pressure environment. A high concentration step of increasing the concentration,
   Precipitation step of precipitating boric acid impregnated inside the object to be treated by lowering the temperature of the concentrated boric acid aqueous solution, provided that the pressurized state is maintained at least until the temperature drops to the boiling point under the atmospheric pressure environment. And a method for producing a non-combustible material.
2. The method for producing a noncombustible material according to claim 1, wherein in the concentration increasing step, the temperature of the boric acid aqueous solution is set to 120 ° C or higher.
3. The method for producing a noncombustible material according to claim 2, wherein in the concentration increasing step, the temperature of the boric acid aqueous solution is set to 140 to 160 ° C.
4. The concentration increasing step is to increase the concentration of the boric acid aqueous solution by dissolving boric acid as a solid substance that has not completely dissolved and is precipitated in the impregnation tank along with the temperature increase of the boric acid aqueous solution. The method for producing a noncombustible material according to any one of claims 1 to 3, wherein:
5. Prior to the step of increasing the concentration, the method further comprises an air removing step of removing air contained in the processing object by placing the impregnation tank into which the processing object is charged under a vacuum pressure environment. The method for producing a non-combustible material according to any one of claims 1 to 3.
6. The method for producing a noncombustible material according to any one of claims 1 to 5, wherein the precipitation step cools the boric acid aqueous solution by heat exchange with a cooling liquid.
7. In noncombustible materials,
   A non-combustible material comprising boric acid, containing no additive for promoting the dissolution of boric acid in water, and having a boric acid content of 180 kg / m ³ or more.
8. In noncombustible materials,
   Contains boric acid, does not contain additives to promote the dissolution of boric acid in water, and has a total calorific value of 8 MJ / m ² or less when heated for 20 minutes in a heat generation test using a corn calorimeter. Non-combustible material characterized by the following.

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