Method for evaluating fireproofed wood

Abstract

To quantitatively evaluate the deliquescence of fireproofed wood.SOLUTION: A method for evaluating fireproofed wood includes: a fireproofed wood exposure step of exposing fireproofed wood subjected to fireproof agent treatment in a predetermined condition; an untreated wood exposure step of exposing untreated wood not subjected to the fireproof agent treatment in the predetermined condition; a fireproofed wood mass increase amount measurement step of measuring an increase in the amount of mass of the fireproofed wood in the fireproofed wood exposure step; and an untreated wood mass increase amount measurement step of measuring an increase in the amount of mass of the untreated wood in the untreated wood exposure step. The deliquescence of fireproofed wood is evaluated on the basis of the comparison between the increase in the amount of mass of the fireproofed wood and the increase in the amount of mass of the untreated wood.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method for evaluating flame-retardant treated wood. [Background technology]

[0002] When using wood for interior wall or ceiling finishes, interior restrictions stipulated by the Building Standards Act must be observed, so special wood called flame-retardant treated wood, which has been impregnated (for example, by pressure impregnation) with a flame-retardant agent, is often used.

[0003] Incidentally, flame retardant chemical components have deliquescent properties (they absorb water vapor (moisture) in the air and dissolve in it to form an aqueous solution), and an aqueous solution of the flame retardant chemicals may precipitate on the surface of the wood (also known as efflorescence). For example, Patent Document 1 discloses a method for evaluating such flame retardant-treated wood, in which the degree of efflorescence on the surface is confirmed after exposing the flame retardant-treated wood to a specified environment for a certain period of time. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6894099 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the above-mentioned Patent Document 1, the degree of efflorescence (deliquescence) on the wood surface is judged qualitatively by visual inspection (for example, judged with ◯, △, or ×), and no quantitative evaluation is performed.

[0006] The present invention has been made in view of the above problems, and an object of the present invention is to quantitatively evaluate the deliquescence of flame-retardant treated wood. [Means for solving the problem]

[0007] The main invention for achieving the above-mentioned object is a method for evaluating flame-retardant treated wood, comprising a flame-retardant treated wood exposure step of exposing flame-retardant treated wood treated with a flame-retardant chemical under specified conditions, an untreated wood exposure step of exposing untreated wood not treated with the flame-retardant chemical under the specified conditions, a flame-retardant treated wood mass gain measurement step of measuring the mass gain of the flame-retardant treated wood due to the flame-retardant treated wood exposure step, and an untreated wood mass gain measurement step of measuring the mass gain of the untreated wood due to the untreated wood exposure step, characterized in that the deliquescent property of the flame-retardant treated wood is evaluated based on a comparison between the mass gain of the flame-retardant treated wood and the mass gain of the untreated wood.

[0008] Other features of the present invention will become apparent from the following detailed description of the present invention and the accompanying drawings. Effect of the Invention

[0009] According to the present invention, the deliquescence of flame-retardant treated wood can be quantitatively evaluated. [Brief description of the drawings]

[0010] [Figure 1] FIG. 2 is a flow diagram of an evaluation method for flame-retardant treated wood in the present embodiment. [Diagram 2] FIG. 2 is a diagram showing the state of a test wood sample placed in a high humidity environment. [Diagram 3] FIG. 1 shows the mass change in untreated wood. [Figure 4] FIG. 1 shows the mass change in treated wood. [Diagram 5] FIG. 13 is a diagram showing an example of evaluation of the coefficient b / a and the mass increase c of dripping and pooled water. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] At least the following points will become apparent from the description of this specification and the accompanying drawings.

[0012] (Aspect 1) A method for evaluating flame-retardant treated wood, comprising: a flame-retardant treated wood exposure step of exposing flame-retardant treated wood under specified conditions; an untreated wood exposure step of exposing untreated wood that has not been treated with a flame-retardant chemical under the specified conditions; a flame-retardant treated wood mass gain measurement step of measuring the mass gain of the flame-retardant treated wood due to the flame-retardant treated wood exposure step; and an untreated wood mass gain measurement step of measuring the mass gain of the untreated wood due to the untreated wood exposure step, wherein the deliquescent property of the flame-retardant treated wood is evaluated based on a comparison between the mass gain of the flame-retardant treated wood and the mass gain of the untreated wood.

[0013] According to the evaluation method of flame-retardant treated wood of embodiment 1, the deliquescence of the flame-retardant treated wood can be quantitatively evaluated.

[0014] (Aspect 2) It is desirable that the evaluation method of flame-retardant treated wood described in aspect 1 further includes a liquid mass gain measurement step of measuring the mass gain of the liquid dripped from the flame-retardant treated wood by the flame-retardant treated wood exposure step, and evaluating the deliquescent property of the flame-retardant treated wood based on the mass gain of the flame-retardant treated wood, the mass gain of the untreated wood, and the mass gain of the liquid.

[0015] According to the evaluation method of flame-retardant treated wood of the second aspect, the deliquescence can be evaluated more accurately.

[0016] (Aspect 3) The method for evaluating flame-retardant treated wood according to aspect 2, further comprising: 3 ), the mass increase of the flame retardant treated wood is b (g / cm 3 ), the mass increase of the liquid is c (g / cm 3 ), it is desirable to evaluate c×b / a.

[0017] According to the evaluation method of flame-retardant treated wood of embodiment 3, c is the result of deliquescence, and b / a is a coefficient indicating the ease of deliquescence, so that the deliquescence can be evaluated by the value of c×b / a.

[0018] (Aspect 4) In the method for evaluating flame-retardant treated wood described in aspect 3, it is desirable to plot based on a, b, and c on a coordinate system in which the magnitude of c is set on the first axis and the magnitude of (b / a) is set on the second axis intersecting the first axis.

[0019] According to the evaluation method of flame-retardant treated wood of embodiment 4, the deliquescent characteristic of the flame-retardant treated wood can be visually understood.

[0020] (Aspect 5) In the method for evaluating flame-retardant treated wood according to any one of the first to fourth aspects, it is preferable to continue measuring each mass increase until each mass increase becomes constant.

[0021] According to the evaluation method of flame-retardant treated wood of the fifth aspect, the mass increase due to deliquescence can be accurately determined, and therefore the deliquescence can be accurately evaluated.

[0022] (Aspect 6) A method for evaluating flame-retardant treated wood, comprising: a flame-retardant treated wood exposure step in which flame-retardant treated wood that has been treated with a flame-retardant chemical is exposed under specified conditions; and a liquid mass gain measurement step in which an increase in mass of a liquid dripped from the flame-retardant treated wood by the flame-retardant treated wood exposure step is measured, and the deliquescence of the flame-retardant treated wood is evaluated based on the increase in mass of the liquid.

[0023] According to the evaluation method of flame-retardant treated wood of the sixth aspect, the deliquescence can be quantitatively evaluated.

[0024] === Implementation form === <<About fire-retardant treated wood>> As part of measures against global warming, efforts are being made to use as much wood as possible in the interior of buildings made of reinforced concrete or steel, which is a source of carbon dioxide fixation. When using wood for wall and ceiling finishes, interior restrictions stipulated by the Building Standards Act must be observed, so a special type of wood called fire-retardant wood is often used.

[0025] Here, fire-retardant treated wood refers to wood that is produced by impregnating the interior (interior of wood) with a specific fire-retardant agent (liquid) in a pressurized container in a manufacturing factory. The wood used for fire-retardant treated wood is not particularly limited, but examples thereof include logs, lumber, sliced ​​veneer, and plywood.

[0026] Flame retardant components include phosphoric acid, diammonium hydrogen phosphate, ammonium dihydrogen phosphate, ammonium carbamyl polyphosphate, diguanidine phosphate, guanylurea phosphate, boric acid, sodium tetraborate (decahydrate), sodium octaborate (tetrahydrate), ammonium sulfate, and sodium hexametaphosphate (see JIS A9011:2020 "Flame retardant treatment method for wood materials"). In practice, phosphoric acid-based compounds and boric acid-based compounds are used in multiple combinations.

[0027] The general method for treating with fire retardants is the "pressure injection method." Specifically, the container containing the wood is sealed and the pressure inside the container is reduced for a certain period of time (for example, reduced to -0.08 MPa or less), and then the container is filled with the working liquid (fire retardant solution) and pressurized (for example, pressurized to 0.5 MPa or more). This allows the fire retardant to be injected into the interior of the wood.

[0028] Finally, the pressure inside the container is reduced (for example, to -0.08 MPa or less) to drain off excess working liquid, and the wood is removed from the container and dried in a prescribed manner.

[0029] Fire-retardant treated wood manufactured in this way can only be used as a wall or ceiling finishing material subject to interior restrictions after going through the required procedures and receiving certification as a "fire-resistant material" or "semi-fire-resistant material" from the Minister of Land, Infrastructure, Transport and Tourism.

[0030] By the way, when selecting an interior finish from among the fire-retardant treated woods of various manufacturers, it is important to choose one that is as unlikely to cause a phenomenon called deliquescence as possible. It is desirable to select the following. Deliquescence is a phenomenon in which a substance, when exposed to the atmosphere, absorbs water (water vapor) from the atmosphere, dissolves in it, and forms an aqueous solution. Deliquescence occurs when the water vapor pressure (saturation vapor pressure) of the saturated aqueous solution of the substance is smaller than the water vapor pressure of the atmosphere in contact with it.

[0031] Because flame retardants are prone to deliquescence, they can absorb water vapor (moisture) from the air during use of flame retardant-treated wood, causing the aqueous solution of the flame retardant to leach onto the wood surface. When the moisture dissipates, the flame retardant precipitates as white crystals, which is known to mar the aesthetic appearance of the wood surface (this phenomenon is also known as efflorescence).

[0032] So far, no method has been proposed to quantitatively evaluate the deliquescence of fire-retardant treated wood. In general, the quality of fire-retardant treated wood is evaluated empirically by actually using the wood.

[0033] In addition, the Japan Housing and Wood Technology Center, a public interest incorporated foundation, has stipulated quality tests for "efflorescence-suppressing painted wood building materials" in its "Quality Performance Evaluation Standards for Superior Wood Building Materials (AQ)." However, this stipulation is a method of visually observing the appearance of the degree of chemical elution from the surface of flame-retardant-treated wood after a prescribed test, and may depend on the subjective judgment of the tester (it is not a quantitative evaluation).

[0034] Therefore, in this embodiment, it is possible to quantitatively evaluate the deliquescence of fire-retardant treated wood.

[0035] <<Evaluation of fire-retardant treated wood>> In this embodiment, the deliquescence of the flame-retardant treated wood was evaluated from the following two viewpoints. (Point 1) It is preferable that the mass of fire-retardant treated wood does not increase easily even when exposed to high humidity. (Point 2) It is better if the mass of dripping and pooling water is less likely to increase.

[0036] Here, the dripped and pooled water in aspect 2 refers to the aqueous solution (corresponding to a liquid) resulting from the deliquescence of the flame retardant chemical that dissolves on the surface of the flame retardant-treated wood and drips (see Figure 2), which directly leads to staining (efflorescence) on the wood surface. Note that in the case of an increase in mass (increase in mass of flame retardant-treated wood) in aspect 1, this includes both the aqueous solution that dissolves on the surface of the wood and that remains inside the wood (not directly connected to staining).

[0037] <Evaluation method> FIG. 1 is a flow diagram of the method for evaluating flame-retardant treated wood in this embodiment.

[0038] First, test wood treated with a flame retardant (impregnated with a flame retardant) (fire retardant treated wood, hereinafter also referred to as treated wood) and test wood not treated with a flame retardant (hereinafter also referred to as untreated wood) were each left (exposed) in a high humidity environment (S01). In step S01, the treated wood corresponds to the flame retardant treated wood exposure step, and the untreated wood corresponds to the untreated wood exposure step. The same wood was used for the treated wood and the untreated wood. Test methods such as preparation of test wood were performed in accordance with JIS Z2101:2009 (Testing methods for wood).

[0039] Figure 2 shows the state of test wood placed in a high humidity environment. As shown in Figure 2, test wood (treated wood in the figure) was placed on a metal tray and left in a high humidity environment (temperature 40°C, humidity 90% RH). Exposure to this high humidity environment caused moisture from the air to be absorbed into the treated wood, increasing the mass of the wood. Figure 2 also shows that an aqueous solution of the flame retardant agent dripped from the treated wood and accumulated in the tray (dripping / accumulated water).

[0040] Untreated wood was also exposed to a high humidity environment in the same way. Even with untreated wood, the wood absorbed moisture when left in a high humidity environment, causing an increase in mass. However, since untreated wood does not contain flame retardant chemicals, the amount of mass increase was smaller than that of treated wood. Furthermore, with untreated wood, no dripping or pooling of water occurred, as will be described later.

[0041] Then, at a predetermined time interval (in this embodiment, at 24-hour (one-day) intervals), the mass increase of each test piece of wood (treated wood, untreated wood) and the mass increase of dripping and pooled water were measured (S02). In step S02, measuring the mass increase of treated wood corresponds to the flame-retardant treated wood mass increase measuring step, and measuring the mass increase of untreated wood corresponds to the untreated wood mass increase measuring step. Also, measuring the mass increase of dripping and pooled water of treated wood corresponds to the liquid mass increase measuring step.

[0042] The mass increase of each test wood (treated and untreated) was calculated by measuring the mass of each test wood before exposure and subtracting the mass measurement result before exposure from the mass measurement result after exposure. The mass increase of dripped and accumulated water was calculated by measuring the mass of the tray (including dripped and accumulated water) after exposure and subtracting the mass of the tray only.

[0043] In this way, the measurement was continued until the mass increase reached a constant weight (hereinafter, n days) on the constant weight day. Note that the constant weight refers to a state in which the mass change is 0.5% or less when measured at intervals of 6 hours (24 hours in this embodiment) (see page 2 of JIS A9011:2020 "Flame retardant treatment method for wood materials" and page 6 of JIS Z2101:2009 "Testing method for wood").

[0044] Then, based on the respective mass increases, the deliquescence of the treated wood was evaluated (S03), as described below.

[0045] Fig. 3 is a graph showing the mass change in untreated wood, and Fig. 4 is a graph showing the mass change in treated wood. The horizontal axis of Fig. 3 and Fig. 4 represents time (h), and the vertical axis represents the mass increase (g / cm 3 ) Note that the amount of fire retardant treatment agent injected into the wood is controlled per unit volume, so the mass increase is converted to per unit volume of the test wood. In this embodiment, the mass was measured every day (24 hours). The plots in the figure with gaps indicate that measurements were not taken on weekends, etc.

[0046] In addition, in Figs. 3 and 4, triangle marks (△) indicate the measurement results of the mass increase of the wood, and circles (◯) indicate the measurement results of the mass increase of the dripped and accumulated water.

[0047] As can be seen from Figure 3, for untreated wood, the mass increase of the wood increased slightly on the first day, but remained almost unchanged thereafter, and dripping and pooling of water was almost zero.

[0048] In contrast, in the case of treated wood in Figure 4, the mass increase of the wood increases up to the fourth day (96h) and remains almost constant thereafter. Also, dripping and pooling water is almost zero until the third day, but begins to increase slightly on the fourth day and remains almost constant at around 400h. Note that the longer the number of days until the constant mass day (n days) (the larger the number of n), the longer the risk of efflorescence may last.

[0049] Here, the constant weight day n is set to 18 days (432 h), and the mass increase of the untreated wood at that time is a (g / cm 3 ), and the mass increase of treated wood is b (g / cm 3 ), and the mass increase of dripping and pooling water in the treated wood is c (g / cm 3 ), then from Figures 3 and 4, a, b, and c will have the following values: a = 0.0304 (g / cm 3 ) b = 0.2273 (g / cm 3 ) c = 0.1837(g / cm 3 )

[0050] The mass increase c occurs as a result of the aqueous solution dripping from the treated wood due to deliquescence of the flame retardant treatment chemical, and as a result of further deliquescence of the dripped aqueous solution.

[0051] Furthermore, the value (b / a) obtained by dividing the mass increase b by the mass increase a is a value (coefficient) indicating the ease of deliquescence of the treated wood.

[0052] Therefore, the value (c×b / a) obtained by multiplying the mass increase c by the coefficient b / a is an index showing the deliquescence of the treated wood, and in this embodiment, c×b / a=1.37. It is preferable that the mass increase c and the coefficient b / a are small. For this reason, it is also preferable that the value of c×b / a is small. By calculating and comparing this value of c×b / a for each flame-retardant treated wood, it is possible to quantitatively evaluate the level of deliquescence (i.e., the risk of efflorescence).

[0053] FIG. 5 is a diagram showing an example of the evaluation of the coefficient b / a and the mass increase c of dripping and pooling water. The horizontal axis of the diagram (corresponding to the first axis) is the mass increase c (g / cm 3 ) and the vertical axis (corresponding to the second axis) represents the coefficient b / a. The results of the above-mentioned treated wood are plotted on the coordinate system defined by the vertical and horizontal axes.

[0054] The deliquescence of each treated wood (characteristics in viewpoints 1 and 2) can be visually understood by conducting similar tests for each treated wood and plotting the results as shown in Fig. 5. For example, if the results for another treated wood are within the range hatched with diagonal lines, that treated wood has better deliquescence than the treated wood of this embodiment.

[0055] ===Other embodiments=== The above-mentioned embodiment is for the purpose of facilitating understanding of the present invention, and is not intended to limit the present invention. The present invention can be modified or improved without departing from the spirit of the present invention, and it goes without saying that the present invention includes equivalents thereof.

[0056] In the above embodiment, the mass increase of untreated wood is expressed as a (g / cm 3 ), and the mass increase of treated wood is b (g / cm 3 ), and the mass increase of dripping and pooling water in the treated wood is c (g / cm 3 ), but the present invention is not limited to this. For example, only b / a may be evaluated, or only c may be evaluated.

[0057] Also, ba = d(g / cm 3 ), then d corresponds to the mass of water absorbed by the flame retardant agent contained in the treated wood (surface and interior). This allows, for example, evaluation of (d+c) / a, or evaluation of d / a or c / a. In these cases, the deliquescence of the flame retardant treated wood can be quantitatively evaluated.

Claims

1. A flame retardant-treated wood exposure step of exposing the flame retardant-treated wood treated with a flame retardant agent under predetermined conditions; An untreated wood exposure step of exposing untreated wood that has not been treated with a flame retardant chemical under the predetermined conditions; a step of measuring the mass gain of the flame-retardant treated wood by the exposure step; and a step of measuring the mass increase of the untreated wood due to the untreated wood exposure step; and evaluating the deliquescence of the flame-retardant treated wood based on a comparison of a mass increase of the flame-retardant treated wood with a mass increase of the untreated wood.

2. A method for evaluating flame-retardant treated wood according to claim 1, The method further includes a liquid mass increase measurement step of measuring a mass increase of the liquid dripped from the flame retardant treated wood by the flame retardant treated wood exposure step; A method for evaluating flame-retardant treated wood, comprising evaluating the deliquescence of the flame-retardant treated wood based on the mass increase of the flame-retardant treated wood, the mass increase of the untreated wood, and the mass increase of the liquid.

3. The method for evaluating flame-retardant treated wood according to claim 2, The mass increase of the untreated wood was a (g / cm ３ ), the mass increase of the flame retardant treated wood is b (g / cm ３ ), the mass increase of the liquid is c (g / cm ３ ) and Evaluate c×b / a A method for evaluating flame-retardant treated wood.

4. The method for evaluating flame-retardant treated wood according to claim 3, A magnitude of c is set on a first axis, and a magnitude of (b / a) is set on a second axis intersecting the first axis, and plotting is performed based on the a, b, and c. A method for evaluating flame-retardant treated wood.

5. A method for evaluating the flame-retardant treated wood according to any one of claims 1 to 4, comprising: Continue measuring each mass increase until each mass increase reaches a constant mass. A method for evaluating flame-retardant treated wood.

6. A flame retardant-treated wood exposure step of exposing the flame retardant-treated wood treated with a flame retardant agent under predetermined conditions; A liquid mass increase measurement step of measuring a mass increase of the liquid dropped from the flame retardant treated wood by the flame retardant treated wood exposure step; and evaluating the deliquescence of the flame-retardant treated wood based on the mass increase of the liquid.

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