Fire resistant structural material

Abstract

To provide a fire resistant structural material that can extend fire resistance time without making a fire-retardant layer thicker.SOLUTION: A fire resistant structural material 1A comprises a load-bearing part 2 made of wood with an approximately rectangular cross section, a fire retardant layer 3 provided on the outside thereof, and a finishing layer 4 provided further on the outside thereof. A sheet-like reflective material 5 is provided between the fire retardant layer 3 and the finishing layer 4, so that the extension width W from the corner parts of the fire retardant layer 3 in its circumferential direction is 25 mm to 100 mm. As the reflective material 5 reflects radiant ingredients from flames, the temperature in the corner parts are suppressed from rising in the event of fire.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a fire-resistant structural material. [Background technology]

[0002] In wooden buildings, fire resistance is required for the structural materials that make up the columns and beams so that they do not collapse even in the event of a fire. It is desirable that the center of the structural materials that support the load does not carbonize even if the surface of the structural materials is exposed to fire and burns. In order to achieve this, for example, a fire-resistant structure that has a fire-stopping layer impregnated with a fire-retardant treatment agent and a surface layer that does not contain the fire-retardant treatment agent has been considered (Patent Document 1). This fire-resistant structure can prevent the progression of carbonization toward the center after the fire ends by adjusting the thickness of the fire-stopping layer so that the burning part at the end of the fire is the part injected with the fire-retardant treatment agent, and the fire stops naturally, preventing the collapse of the building. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 4958098 Summary of the Invention [Problem to be solved by the invention]

[0004] In order to extend the fire resistance time, it is possible to simply thicken the fire-retardant layer. However, thickening the fire-retardant layer not only compresses the indoor space, but also increases the cost of wood and fire-retardant treatment chemicals, which is undesirable from the viewpoint of resource conservation. Therefore, the object of the present invention is to provide a fire-resistant structural material that can extend the fire resistance time without thickening the fire-retardant layer. [Means for solving the problem]

[0005] The present invention provides a fire-resistant structural material comprising a load-supporting section made of a wood material and having a substantially rectangular cross section, a fire-retardant layer provided on the outside of the load-supporting section, and a finishing layer provided on the outside of the fire-retardant layer, in which a sheet-like reflective material is provided between the fire-retardant layer and the finishing layer so that the extension width from the corners of the fire-retardant layer in the circumferential direction of the fire-retardant layer is 25 mm to 100 mm.

[0006] When structural members such as pillars and beams are rectangular, in the event of a fire, the corners of the structural members are exposed to the flames on both sides, so they are prone to become hot and burn easily. In the fire-resistant structural member of the present invention, a sheet-like reflective material is provided in a predetermined width from the corners of the fire-stopping layer in the circumferential direction, and the reflective material reflects the radiation components from the flames, suppressing the temperature rise of the corners.

[0007] The fire-resistant structural material of the present invention may have one or more of the following characteristics: The fire-retardant layer may be wood impregnated with a fire-retardant treatment. The thickness of the fire-retardant layer may be 30mm to 70mm. The finishing layer may be wood, in which case the thickness of the finishing layer may be 20-40mm. The cross section of the fire-retardant layer is rectangular with right-angled corners, the reflective material has a fibrous backing material on one side, the side of the reflective material having the backing material faces the fire-retardant layer, and the reflective material may be provided separately from each other on the two sides of the fire-retardant layer that form the corners. The cross section of the fire-retardant layer is rectangular with rounded corners, the reflective material has a fibrous backing on one side, the side of the reflective material with the backing faces the fire-retardant layer, and the reflective material may be continuous across both sides of the fire-retardant layer that sandwich the corners. Effect of the Invention

[0008] According to the present invention, it is possible to provide a fire-resistant structural material that can extend the fire-resistant time without increasing the thickness of the fire-retardant layer. [Brief description of the drawings]

[0009] [Figure 1] 1 is a cross-sectional view of a fire-resistant structural material according to one embodiment of the present invention. [Diagram 2] FIG. 2 is an enlarged view of a corner of a fire-resistant structural material. [Diagram 3] 10A and 10B are both enlarged views of a corner of a cross section of a fire-resistant structural material according to another embodiment. [Figure 4] FIG. 2 is a cross-sectional view of a fire-resistant structural material according to another embodiment. [Diagram 5] FIG. [Figure 6] 1 is a graph showing temperature changes. [Figure 7] 1 is a graph showing temperature changes. [Figure 8] 1 is a photograph of a cross section of a test specimen after testing. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] The fire-resistant structural material of the present invention is made of wood, and is intended to be used mainly as a pillar or beam, and to improve its fire resistance. A preferred embodiment of the present invention will be described in detail below with reference to the drawings. Note that the same or corresponding parts in each drawing are given the same reference numerals, and duplicated explanations will be omitted. In addition, in order to emphasize the features of the invention, the dimensional ratios of each member are different from the actual dimensional ratios.

[0011] <Fireproof structural materials> As shown in FIG. 1, the fireproof structural material 1A of this embodiment is an example of a column, and includes a load-bearing part 2 that is long and has a square cross section, a fire-retardant layer 3 provided on the outside of the load-bearing part 2, and a finishing layer 4 provided on the outside of the fire-retardant layer 3. Here, the "outside" refers to the side that is visible in the radial direction of the fireproof structural material 1A. In the fireproof structural material 1A, the fire-retardant layer 3 is arranged so as to surround the entire outer periphery of the side of the load-bearing part 2 that forms the center part, and the finishing layer 4 is arranged so as to surround the entire outer periphery of the fire-retardant layer 3. Note that, although each part is drawn as if it were a single solid piece of wood in FIG. 1, FIG. 1 shows the layout concept of each part, and in reality, it may be a laminated material formed by pressing together using a resorcinol-based resin adhesive or the like. Note that FIG. 5 described later shows how each part is composed of laminated wood.

[0012] The load support portion 2 is a core material that supports the load of the building. The load support portion 2 is made of wood, and the specific type and density of the wood may be the same as that used for the fire-retardant layer 3 described later, or may be a wood species with higher density and higher structural performance. The size of the cross section of the load support portion 2 may be 120 mm to 680 mm, 180 mm to 560 mm, or 240 mm to 440 mm as one side of a square. When the fire-resistant structural material 1A is a beam, the beam cross section may have a beam depth of 120 mm to 890 mm and a beam width of 120 mm to 480 mm.

[0013] The fire-retardant layer 3 functions as a layer that stops the progress of carbonization of the fire-resistant structural material 1A in the event of a fire, and is designed to be thick enough that it will not burn down completely in the thickness direction even during a fire. Materials that make up the fire-retardant layer 3 include wood injected with a fire-retardant treatment agent, and non-combustible materials such as gypsum board and mortar.

[0014] Generally, the greater the density of wood, the slower the thermal conductivity and the less likely it is to burn. Therefore, when the fire-retardant layer 3 is made of wood, the density of the wood is 400 kg / m 3 It is preferable that the resistance is 450 kg / m or more. 3More preferably, it is 480 kg / m or more. 3 More preferably, the upper limit is 600 kg / m 3 , 580kg / m 3 , 550kg / m 3 Examples of wood having such a density include larch, cypress, fir, Japanese cedar, white pine, Yezo spruce, camphor tree, red pine, etc. In terms of the abundance of resources and market price, larch is preferred.

[0015] The wood constituting the fire-retardant layer 3 has a density of 400 kg / m3 so that it is easy to impregnate with the fire-retardant treatment agent. 3 The density may be less than 390 kg / m 3 may be less than 380 kg / m 3 The lower limit of the density is 250 kg / m 3 , 270kg / m 3 , 290kg / m 3 Examples of wood having such density include cedar, Paulownia, and Japanese black pine. When wood with low density is selected, it may be necessary to make the fire-retardant layer 3 thicker than when wood with high density is selected. Cedar is suitable in terms of abundance of resources and market price.

[0016] The fire-retardant treatment agent injected into the wood that constitutes the fire-retardant layer 3 can be of any type, such as phosphorus-based, nitrogen-based, boron-based, or halogen-based agents. The method for injecting the fire-retardant treatment agent into the wood can be any method, such as immersion, coating, spraying, or reduced pressure / pressure treatment.

[0017] The thickness of the fire-retardant layer 3 varies depending on the type of wood that constitutes the fire-retardant layer 3 and the desired fire resistance time, but if fire resistance of, for example, 1 hour and 30 minutes is desired, the thickness is preferably 30 mm to 70 mm, and more preferably 40 mm to 60 mm.

[0018] The fire-retardant layer 3 can be fixed to the load-supporting portion 2 by applying a resorcinol-based resin adhesive or the like and then pressing.

[0019] The finishing layer 4 is also called the decorative layer, and is the layer that building users come into contact with on a daily basis. Since the finishing layer 4 may be touched by hand, if the fire-retardant layer 3 contains a fire-retardant treatment agent, it acts as a lid to prevent the fire-retardant treatment agent from leaking out. Materials constituting the finishing layer 4 include the same wood as that constituting the fire-retardant layer 3, and in particular, cedar or larch is preferable.

[0020] The thickness of the finishing layer 4 is preferably 20 mm to 40 mm, more preferably 25 mm to 35 mm, and even more preferably 28 mm to 33 mm. Since the production of the fire-retardant layer 3 requires a lot of time and cost, in order to improve the fire resistance of the fire-resistant structural material 1A, by setting the thickness of the finishing layer 4, which is the outermost layer and can be produced relatively easily, within the above range, it is possible to easily gain time for heat to be transmitted to the inside.

[0021] The normal carbonization speed of wood is, for example, about 0.6 mm / min. In this case, the thickness required for the finishing layer 4 can be calculated by multiplying this by the fire resistance time to be imparted. For example, if a fire resistance time of 30 minutes is to be imparted, the finishing layer 4 should be made 0.6 mm / min x 30 = 18 mm thick. In the past, when a decorative layer with a thickness of 10 mm was used as the finishing layer, the thickness of the finishing layer 4 in this embodiment is 10 mm + 18 mm = 28 mm. On the other hand, if the finishing layer 4 is made too thick, the burning time as a combustible material will be longer and the thermal effect on the load support part 2 will be greater, so the upper limit of the thickness of the finishing layer 4 is preferably the above value.

[0022] The method of fixing the finishing layer 4 to the fire-retardant layer 3 may be the same as the method of fixing the fire-retardant layer 3 to the load-bearing part 2 .

[0023] The fireproof structural material 1A is provided with sheet-like reflective materials 5 at the four corners of the fireproof layer 3 between the fireproof layer 3 and the finishing layer 4. As shown in FIG. 2, the reflective materials 5 each have a predetermined extension width W from the corners of the fireproof layer 3 in the circumferential direction of the fireproof layer 3. In this embodiment, the reflective material 5 is in the form of a single sheet folded at the corners so that it forms an L-shape with the corners as the center in the cross section. The extension width W is preferably 25 mm to 100 mm, more preferably 28 mm to 80 mm, and even more preferably 30 mm to 60 mm. The extension width W may be common to the four corners or may be different from each other.

[0024] The reflective material 5 extends in the longitudinal direction of the fire-resistant structural material 1A with a uniform extension width W. That is, when the fire-resistant structural material 1A is a column, the reflective material 5 is provided from the capital to the base, and when the fire-resistant structural material 1A is a beam, the reflective material 5 is provided over the entire length of the beam.

[0025] The constituent material of the reflective material 5 is preferably a material capable of reflecting the radiant component of heat, and is preferably a metal. Specific examples of materials with high reflectivity include silver, aluminum, mercury, etc. In particular, aluminum is preferable. In this embodiment, the reflective material 5 is configured as a single reflective layer 5A made of a single material.

[0026] From the viewpoint of reducing the step occurring between the fire-retardant layer 3 and the finishing layer 4, the thickness of the reflective layer 5A may be 0.05 mm to 1.0 mm, 0.1 mm to 0.8 mm, or 0.2 mm to 0.6 mm.

[0027] To fix the reflective material 5 to the fire-retardant layer 3, an epoxy resin adhesive is preferably used.

[0028] <Effects> When structural members such as pillars and beams have a rectangular cross section, in the event of a fire, the corners of the structural members are exposed to flames on both sides, making them prone to high temperatures and flammability. In this regard, the fire-resistant structural member 1A of this embodiment has a sheet-like reflecting material 5 provided at a specified width from the corners of the fire-retardant layer 3 in the circumferential direction, so that the reflecting material 5 reflects the radiation component of the flame and suppresses radiant heat transfer. This suppresses the temperature rise at the corners.

[0029] In this embodiment, the reflective material 5 is provided between the fire-retardant layer 3 and the finishing layer 4. If the reflective material 5 were provided between the fire-retardant layer 3 and the load-supporting portion 2, it would be difficult to obtain the effect of suppressing radiant heat transfer. From the viewpoint of heat conduction, it is considered that the heat transfer to the load-supporting portion 2 will be the same regardless of whether the reflective material 5 is provided between the fire-retardant layer 3 and the finishing layer 4 or between the fire-retardant layer 3 and the load-supporting portion 2. However, in terms of the effect of blocking radiant heat, the reflective material 5 can be more effectively suppressed from transferring heat to the load-supporting portion 2 by arranging it "between the fire-retardant layer 3 and the finishing layer 4," which is closer to the fire surface.

[0030] Due to the amendment of the Building Standards Act Enforcement Order in 2023, the fire resistance time required for wooden buildings has been changed. After the amendment, 1 hour fire resistance is required for the first 4 floors counting from the top floor, and 1 hour 30 minutes fire resistance is required for the 5th to 9th floors counting from the top floor. In addition, 2 hours fire resistance is required for the 10th to 14th floors counting from the top floor, and 2 hours 30 minutes fire resistance is required for the 15th to 19th floors counting from the top floor. The fire-resistant structural material 1A of the present embodiment is particularly effective in improving the fire resistance of a structural material that has a conventional 1 hour fire resistance performance to 1 hour 30 minutes fire resistance performance without increasing the thickness of the fire-stopping layer.

[0031] Although the preferred embodiment of the present invention has been described above, the present invention is not limited to the above embodiment. For example, the above embodiment shows a mode in which the load support portion 2 has a square cross section, but the load support portion may have a rectangular cross section, and may also be rectangular. In this case, the extension width W of the reflector 5 may be the same as when the cross section is square.

[0032] In the above embodiment, the reflective material 5 is a reflective layer 5A made of a single material. However, as shown in FIG. 3(A), the reflective material 5 may have a reflective layer 5A and a fibrous backing material 5B on one side of the reflective layer 5A. If the reflective layer 5A is thin, it may be torn when it is attached to the fire-retardant layer 3, which makes the workability poor. This problem can be improved by using a sheet of the reflective material 5 backed by a fiber reinforcement material such as glass mesh. However, the flexibility of the reflective material with the backing material is poor, and it is difficult to bend the reflective material into an L-shape and attach it to a right-angled corner. In this case, as shown in FIG. 3(A), it is preferable to provide the reflective material 5 separately on the two sides constituting the corner of the circumferential surface of the fire-retardant layer 3. This makes it easy to attach the reflective material 5 to the corner without any gaps. At this time, the backing material 5B is attached so that it faces the fire-retardant layer 3.

[0033] In addition, in the above embodiment, the corners of the fire-retardant layer 3 are right angles, but the corners of the fire-retardant layer 3 may be rounded, as in the fire-resistant structural material 1C shown in Fig. 3(B). In this case, even when a reflective material 5 having a backing material 5B is used, the rounded shape can be followed, so that one piece of reflective material 5 can be attached continuously across the two surfaces that sandwich the corners.

[0034] In addition, while the above embodiment shows a configuration in which the fire-resistant structural material is not in contact with other structural materials (mainly columns), the fire-resistant structural material may be in a configuration in which it is in contact with the underside of the floor slab 6 (mainly beams), as in the fire-resistant structural material 1D shown in Fig. 4. In this case, the side of the fire-resistant structural material 1D in contact with the floor slab 6 is not exposed to flames from two sides in the event of a fire, and therefore no reflective material 5 is required. EXAMPLES

[0035] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[0036] Assuming that the pillars are fireproof, aluminum sheets were used as reflective materials. In order to verify the effect of the aluminum sheets in suppressing radiative heat transfer, tests were conducted with the aluminum sheets extended at widths of 50 mm and 20 mm.

[0037] <Production of test specimen> Specimen 1E shown in Figure 5 was prepared. A 120 mm square cedar laminated timber was prepared as the core material (load-bearing portion). Thermocouples S1 to S8 for measuring temperature were attached as temperature sensors at eight locations shown in Figure 5 (the four corners of the core material and the center between each corner). A 50 mm thick cedar laminated timber (amount of fire-retardant treatment agent fixed = 156 kg / m2) was placed around the core material as a fire-retardant layer. 3 (injected with fire-retardant material to make it fire-retardant) was bonded with a resorcinol-based resin adhesive. The corners of the fire-retardant layer were right angles. Two types of 0.2 mm thick aluminum sheets backed with glass mesh were prepared, one with a width of 20 mm and the other with a width of 50 mm. As shown in Fig. 5, two of the four corners were bonded with an aluminum sheet with an extension width of W1 = 50 mm with an epoxy resin adhesive, and the other two corners were bonded with an aluminum sheet with an extension width of W2 = 20 mm. Finally, a 30 mm thick cedar wood was bonded with a resorcinol-based resin adhesive as a decorative layer around the fire-retardant layer. In this way, specimen 1E, a mock pillar with a horizontal cross section of 280 mm square and a total length of 700 mm, was produced.

[0038] <Testing and Evaluation> Test specimen 1E was placed in a fireproof furnace, the lid was placed on it, and it was heated for 90 minutes according to the ISO834 curve. After heating, the test was continued until the maximum temperature was confirmed by thermocouples S1 to S8, after which the specimen was removed from the furnace and its cross section was examined. The results of the temperature change are shown in Figures 6 and 7. The cross-sectional observation is shown in Figure 8.

[0039] The test result was deemed to have passed if both of the following two evaluation items were met. Evaluation item 1: The temperature of the thermocouple placed at the boundary between the core material and the fire-stopping layer must not reach 260°C, which is the ignition temperature of wood. Evaluation item 2: When the cross section was observed after the test, carbonization had not progressed to the core material.

[0040] On the side of the test specimen where the aluminum sheet was 50 mm wide, the thermocouple temperature did not exceed 260°C at any of the three points (Fig. 6). Additionally, cross-sectional observation showed that the carbonization at the corners had not reached the core material (left side of Fig. 8). In contrast, on the side where the aluminum sheet was 20 mm wide, the thermocouple temperature exceeded 260°C at one corner (Fig. 7), and cross-sectional observation showed that the carbonization had reached the core material at that corner (right side of Fig. 8). [Industrial Applicability]

[0041] The present invention can be used in wooden buildings. [Explanation of symbols]

[0042] 1A, 1B, 1C, 1D...fire-resistant structural material, 1E...test specimen (fire-resistant structural material), 2...load-bearing part, 3...fire-retardant layer, 4...finishing layer, 5...reflective material, 5A...reflective layer, 5B...lining material, 6...floor slab, S1 to S8...thermocouples, W, W1, W2...extension width.

Claims

1. A load support portion made of wood and having a substantially rectangular cross section; A fire-retardant layer provided on the outer side of the load-bearing portion; A fire-resistant structural material comprising a finishing layer provided on the outside of the fire-retardant layer, A fire-resistant structural material in which a sheet-like reflective material is provided between the fire-retardant layer and the finishing layer so that the extension width of the fire-retardant layer from the corner of the fire-retardant layer in the circumferential direction is 25 mm to 100 mm.

2. 2. The fire-resistant structural material according to claim 1, wherein the fire-retardant layer is wood impregnated with a fire-retardant treatment agent.

3. 3. The fire-resistant structural material according to claim 1, wherein the fire-retardant layer has a thickness of 30 mm to 70 mm.

4. The finish layer is wood, The fire-resistant structural material according to claim 1 or 2, wherein the finishing layer has a thickness of 20 mm to 40 mm.

5. The cross section of the fire-retardant layer is rectangular with right-angled corners; The reflective material has a fibrous backing on one side, The surface of the reflector having the backing material faces the fire-retardant layer, 3. The fire-resistant structural material according to claim 1, wherein the reflecting material is provided separately on two surfaces of the fire-retardant layer that constitute the corner portion.

6. The cross section of the fire-retardant layer is a rectangle with rounded corners, The reflective material has a fibrous backing on one side, The surface of the reflector having the backing material faces the fire-retardant layer, 3. The fire-resistant structural material according to claim 1, wherein the reflective material is continuous over two surfaces of the fire-retardant layer that sandwich the corner portion.

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