Fire-resistant structural materials, method for manufacturing fire-resistant structural materials

Abstract

The present invention provides a fire-resistant structural material that can meet specified fire resistance performance while reducing the thickness of the fire-stopping layer. [Solution] The fire-resistant structural material 1A comprises a load-bearing section 2 made of wood with a substantially rectangular cross-section, a fire-stopping layer 3 surrounding the load-bearing section 2 while having corners, and a finishing layer 4 made of wood surrounding the fire-stopping layer 3. In a cross-sectional view, the corners of the fire-stopping layer 3 are heat-insulating improvement sections 3a with a thermal conductivity of 0.06 W / (m·K) or less, the fire-stopping layer 3 is made of wood in parts other than the heat-insulating improvement sections 3a, the thickness of the fire-stopping layer 3 is 10 mm to 40 mm, the thickness of the finishing layer 4 is 40 mm or more, and the density of the wood constituting the finishing layer 4 is 350 kg / m³ 3 That concludes the explanation. Fire-resistant structural material 1A has high fire resistance because the corners, which are exposed to flames on two sides, are protected in particular.

Description

[Technical Field]

[0001] The present invention relates to a fire-resistant structural material and a method for producing the same. [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 in the event of a fire. Even if the surface of the structural material is burned when exposed to flames, the core (load-bearing part) that supports the load must not be carbonized. To achieve this, it is thought that the fire resistance of the corners, which are heated from two sides in the event of a fire, should be increased. Conventionally, fire-resistant structures have been considered in which, for example, a heat buffer material is provided at the corners of the core material to buffer the transfer of heat (Patent Document 1). In this fire-resistant structure, the temperature rise at the corners is suppressed by the heat buffer material. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Patent No. 7499031 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] In all embodiments disclosed in Patent Document 1, the heat buffer material is made of steel, resulting in high thermal conductivity in this portion. Furthermore, generally, considering the cost of materials, there is a demand to make the fire-stopping layer as thin as possible. Therefore, the present invention aims to provide a fire-resistant structural material that can satisfy predetermined fire resistance performance while keeping the fire-stopping layer thin. It also aims to provide a method for manufacturing such a fire-resistant structural material. [Means for solving the problem]

[0005] The present invention relates to a fire-resistant structural material comprising: a load-bearing portion made of wood with a substantially rectangular cross-section; a fire-stopping layer surrounding the load-bearing portion while having corners; and a finishing layer made of wood surrounding the fire-stopping layer, wherein, in a cross-sectional view, the corners of the fire-stopping layer are heat-insulating improved portions with a thermal conductivity of 0.06 W / (m·K) or less; the portion of the fire-stopping layer other than the heat-insulating improved portions is made of wood; the thickness of the fire-stopping layer is 10 mm to 40 mm; the thickness of the finishing layer is 40 mm or more; and the density of the wood constituting the finishing layer is 350 kg / m³ 3 The above provides a fire-resistant structural material.

[0006] When structural members such as columns and beams are roughly rectangular, during a fire, the corners of the structural members are exposed to flames on two sides, making them prone to high temperatures and thus a weak point in terms of fire resistance. In this regard, the fire-resistant structural material of the present invention has a heat-insulating section at the corner of the fire-stopping layer with a thermal conductivity of 0.06 W / (m·K) or less, resulting in slow heat conduction and higher fire resistance compared to materials made solely of wood. Furthermore, the fire-resistant structural material of the present invention has high fire resistance because the wood constituting the finishing layer is thick and dense. For these reasons, the fire-resistant structural material of the present invention can reduce the thickness of the fire-stopping layer.

[0007] The fire-resistant structural material of the present invention may have one or more of the following features. • The thickness of the finishing layer is 70 mm or more. • The density of the wood that makes up the fire-stopping layer is 400 kg / m³ 3 It is less than. • The insulation improvement section is made of rock wool or a material containing resin.

[0008] The present invention also relates to a method for producing a fire-resistant structural material comprising: a load-bearing portion made of wood with a substantially rectangular cross-section; a fire-stopping layer surrounding the load-bearing portion while having corners; and a finishing layer made of wood surrounding the fire-stopping layer, wherein in a cross-sectional view, the corners of the fire-stopping layer are heat-insulating improved portions with a thermal conductivity of 0.06 W / (m·K) or less, and the portion of the fire-stopping layer other than the heat-insulating improved portion is made of wood, wherein a first fire-stopping layer material and a second fire-stopping layer material, which are part of the wood constituting the fire-stopping layer, are placed on two adjacent surfaces of the load-bearing portion, and a first finishing layer material, which is part of the wood constituting the finishing layer, is placed on the first fire-stopping layer material, The present invention provides a method for manufacturing a fire-resistant structural material, comprising: a groove forming step of bonding the second fire-stopping layer material together, cutting at least one of them so that the outer surface of the second fire-stopping layer material and the end of the first finishing layer material are located in the same plane, and forming a first groove between the end of the first fire-stopping layer material, the end of the second fire-stopping layer material, and the inner surface of the first finishing layer material; a heat-insulating improvement section forming step of placing a first heat-insulating improvement member, which is a component of the heat-insulating improvement section and is processed into an axial shape, into the first groove; and a covering step of bonding a second finishing layer material, which constitutes a finishing layer, to cover the second fire-stopping layer material, the end of the first finishing layer material, and the first heat-insulating improvement member.

[0009] In this manufacturing method, in the groove forming step, a third fire-stopping layer material, which is part of the wood constituting the fire-stopping layer, is bonded to the surface opposite to the surface to which the first fire-stopping layer material of the load-supporting part is bonded, and a third finishing layer material, which is part of the wood constituting the finishing layer, is bonded to the third fire-stopping layer material. At least one of the outer surface of the second fire-stopping layer material and the end face of the third finishing layer material are cut so that they are in the same plane, and a second groove is formed between the end face of the second fire-stopping layer material, the end face of the third fire-stopping layer material, and the inner surface of the third finishing layer material. In the heat insulation improvement section forming step, a second heat insulation improvement member, which is a component of the heat insulation improvement section and is processed into an axial shape, is placed in the second groove, and in the covering step, the second finishing layer material may be bonded so as to cover the second fire-stopping layer material, the end face of the first finishing layer material, the first heat insulation improvement member, the end face of the third finishing layer material, and the second heat insulation improvement member.

[0010] The present invention also relates to a method for manufacturing a fire-resistant structural material comprising: a load-bearing portion made of wood with a substantially rectangular cross-section; a fire-stopping layer surrounding the load-bearing portion while having corners; and a finishing layer made of wood surrounding the fire-stopping layer, wherein in a cross-sectional view, the corners of the fire-stopping layer are heat-insulating improved portions with a thermal conductivity of 0.06 W / (m·K) or less, and the portion of the fire-stopping layer other than the heat-insulating improved portions is made of wood, wherein fire-stopping layer material, which is wood constituting the fire-stopping layer other than the corners, is bonded to all four sides of the load-bearing portion, and finishing layer material, which is wood constituting the finishing layer, is bonded to the outer surfaces of two fire-stopping layer materials facing each other across the load-bearing portion. The present invention provides a method for manufacturing a fire-resistant structural material, which involves cutting the outer surface of a fire-stopping layer material that has not been bonded with a finishing layer material and the end surface of the finishing layer material so that they are located in the same plane, forming grooves at the corners of the fire-stopping layer at the end surface of the fire-stopping layer material with the finishing layer material bonded to it, the end surface of the fire-stopping layer material that has not been bonded with a finishing layer material, and the inner surface of the finishing layer material, respectively, and placing axially processed thermal insulation improvement members, which are components of the thermal insulation improvement section, into the grooves, and then bonding another finishing layer material so as to cover the outer surface of the fire-stopping layer material that has not been bonded with a finishing layer material, the end surface of the finishing layer material, and the thermal insulation improvement members.

[0011] In this manufacturing method, at least one of the outer surface of the first-bonded finishing layer and the end surface of the second-bonded finishing layer may be trimmed so that they are flush with each other. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide a fire-resistant structural material that can satisfy a predetermined fire resistance performance while making the fire-stopping layer thinner. Furthermore, according to the present invention, it is possible to provide a method for manufacturing such a fire-resistant structural material. [Brief explanation of the drawing]

[0013] [Figure 1] This is a cross-sectional view of a fire-resistant structural material according to the first embodiment of the present invention. [Figure 2] This is a cross-sectional view showing the manufacturing process of fire-resistant structural materials. [Figure 3] It is a cross-sectional view showing the manufacturing process of the fire-resistant structural material. [Figure 4] It is a cross-sectional view of the fire-resistant structural material according to the first embodiment of the present invention. [Figure 5] It is a cross-sectional view of the fire-resistant structural material according to the second embodiment of the present invention. [Figure 6] (A) to (D) are all cross-sectional views showing the aspects of the heat insulation improvement part.

Embodiments for Carrying out the Invention

[0014] The fire-resistant structural material of the present invention is made of wood, and is mainly assumed to be used as a column or a beam, and improves its fire resistance. In the present invention, "meeting the fire resistance" means that the entire load-bearing part including the corners of the load-bearing part does not carbonize during the required fire resistance time. Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In each figure, the same part or corresponding part is denoted by the same reference numeral, and duplicate explanations are omitted.

[0015] <First Embodiment> [Fire-resistant Structural Material] As shown in FIG. 1, the fire-resistant structural material 1A of the present embodiment takes a column as an example, and includes a load-bearing part 2 that is long and has a substantially square cross-section, a charring prevention layer 3 provided outside the load-bearing part 2, and a finish layer 4 provided outside the charring prevention layer 3. Here, "outside" refers to the side that is visually recognized in the radial direction of the fire-resistant structural material 1A. The fire-resistant structural material 1A has the charring prevention layer 3 arranged so as to surround the entire outer periphery of the side surface of the load-bearing part 2 forming the central part thereof, and the finish layer 4 is arranged so as to surround the entire outer periphery of the charring prevention layer 3. In addition, although each part is depicted as if it were a solid wood material in FIG. 1, FIG. 1 only shows the arrangement concept of each part, and actually, it may be a laminated wood material formed by compressing a plurality of laminates using an adhesive. Further, the fire-resistant structural material 1A may be a beam, and the cross-section may be rectangular.

[0016] The load-bearing section 2 is the core material that supports the load of the building. The load-bearing section 2 is made of wood, and the specific type and density of the wood may be the same as the wood used as the fire-stopping layer 3 described later, or a tree species with higher density and structural performance may be used. The size of the cross-section of the load-bearing section 2 may be 120 mm to 2000 mm, 180 mm to 560 mm, or 240 mm to 440 mm as the side length of a square. If the fire-resistant structural material 1A is a beam, the beam cross-section may have a beam depth of 120 mm to 1500 mm and a beam width of 120 mm to 480 mm.

[0017] The fire-stopping layer 3 functions as a layer that stops the progression of carbonization of the fire-resistant structural material 1A during a fire, and is designed to be thick enough that it will not be completely burned in its thickness direction even during a fire. The fire-stopping layer 3 surrounds the load-bearing section 2 while having corners, and consists of a solid heat-insulating member (heat-insulating section) 3a that constitutes the corners and a plate-like wooden section 3b that constitutes the parts other than the corners. The material that makes up the wooden section 3b is wood that has been injected with a flame-retardant treatment agent.

[0018] The wood constituting the wood section 3b has a density of 400 kg / m³ to facilitate impregnation with flame-retardant treatment agents. 3 It may be less than 390 kg / m³. 3 It may be less than 380 kg / m 3 It may be less than 250 kg / m³. 3 , 270 kg / m 3 , 290 kg / m 3 Examples include cedar, paulownia, and Japanese black pine, which have such density. Cedar is preferred due to its abundance of domestic resources and market price.

[0019] The flame retardant injected into the wood constituting the wood portion 3b can be of any type, including phosphorus-based, nitrogen-based, boron-based, and halogen-based agents. The method of injecting the flame retardant into the wood can be any method, including immersion, coating, spraying, and vacuum / pressure treatment.

[0020] The thickness of the wood portion 3b varies depending on the type of wood that makes up the fire-stopping layer 3 and the desired fire resistance time. For example, if 60 minutes of fire resistance is desired, the thickness is 10 mm to 40 mm. This thickness may also be 10 mm to 30 mm, 11 mm to 20 mm, or 12 mm to 18 mm. If 90 minutes of fire resistance is desired, the thickness may be 10 mm to 60 mm, 10 mm to 50 mm, 10 mm to 40 mm, 10 mm to 30 mm, 11 mm to 20 mm, or 12 mm to 18 mm.

[0021] One method for fixing the wooden part 3b to the load-bearing part 2 is to apply a resorcinol-based resin adhesive or the like and then press it down.

[0022] The thermal conductivity of the heat-insulating member 3a is lower than that of the wood part 3b, specifically 0.06 W / (m·K) or less. The thermal conductivity of the heat-insulating member 3a may be 0.05 W / (m·K) or less, 0.04 W / (m·K) or less, 0.03 W / (m·K) or less, or 0.02 W / (m·K) or less. The lower limit of the thermal conductivity may be 0.001 W / (m·K), 0.003 W / (m·K), or 0.005 W / (m·K). The thermal conductivity of cedar wood, which can be used as the wood part 3b, is approximately 0.087 W / (m·K).

[0023] In this specification, the value of "thermal conductivity" is the value at room temperature. Here, "room temperature" refers to the range of 20°C to 30°C, 21°C to 29°C, 22°C to 28°C, 23°C to 27°C, or 24°C to 26°C, or 25°C. "Value at room temperature" means the value measured at a specific temperature within the range of room temperature.

[0024] As materials for the heat insulation improvement member 3a, on the premise of having the above thermal conductivity, materials containing rock wool or resin can be mentioned. Examples of the resin include phenolic resin and the like. The resin may be in the form of foam (a state in which bubbles are dispersed).

[0025] As a method of fixing the heat insulation improvement member 3a to the corner of the fire prevention layer 3, as will be described later, it is possible to push the material of the axially formed heat insulation improvement member 3a into a groove formed by the ends of two adjacent wood parts 3b and the inner surface of the finish layer 4. At this time, from the viewpoint of smooth production, it is preferable to apply an adhesive to the inner surface of the groove and then push the heat insulation improvement member 3a in.

[0026] The finish layer 4 is a layer also called a decorative layer and is a layer that building users come into daily contact with. Since the finish layer 4 may be touched by the hands of building users, when the fire prevention layer 3 contains a flame retardant treatment agent, it serves as a lid to prevent the flame retardant treatment agent from flowing out to the outside. As the material constituting the finish layer 4, wood is desirable as in the case of the wood constituting the fire prevention layer 3, and in particular, cedar or larch is preferable. Alternatively, as the material constituting the finish layer 4, it is preferable that the density is higher than that of the wood constituting the fire prevention layer 3.

[0027] Generally, since wood has slower heat conduction and is more difficult to burn as its density is higher, the wood constituting the wood part 3b has a density of 350 kg / m 3 or more is used. This density may be 400 kg / m 3 or more, may be 450 kg / m 3 or more, and may be 480 kg / m 3 or more. Examples of such wood having such a density include cedar, larch, cypress, fir, hiba, white pine, spruce, Japanese elm, red pine, etc. From the perspective of the abundance of domestic resources and market prices, cedar or larch is suitable. From the perspective of density and high self-extinguishability, larch is suitable.

[0028] The thickness of the finishing layer 4 is 40 mm or more if a 60-minute fire resistance performance is desired. This thickness may be 41 mm to 80 mm, 42 mm to 70 mm, 43 mm to 60 mm, or 44 mm to 50 mm. Since the production of the fire-stopping layer 3 is time-consuming and expensive, in order for the fire-resistant structural material 1A to meet the required fire resistance performance, the thickness of the outermost layer, the finishing layer 4, which is relatively easy to produce, is set within the above range to allow time for heat to be transferred to the interior. Furthermore, if a 90-minute fire resistance performance is desired, the thickness of the finishing layer 4 may be 70 mm or more, 75 mm to 110 mm, or 80 mm to 100 mm.

[0029] Furthermore, the total thickness of the fire-stopping layer 3 and the finishing layer 4 may be 50 mm to 100 mm, 52 mm to 90 mm, or 55 mm to 80 mm if a 60-minute fire resistance performance is desired. This thickness may be 80 mm to 130 mm, 90 mm to 120 mm, or 95 mm to 110 mm if a 90-minute fire resistance performance is desired.

[0030] The finishing layer 4 can be provided by attaching four plate-shaped finishing layer materials having the above-mentioned thickness to each surface of the rectangular fire-stopping layer 3 in cross-sectional view. The finishing layer material can be fixed to the fire-stopping layer 3 by applying a resorcinol-based resin adhesive and pressing it down, or by using metal fixing members such as screws or nails.

[0031] The normal carbonization rate of wood is approximately 0.6 mm / min. In this case, the required thickness of the finishing layer 4 can be calculated by multiplying this by the desired fire resistance time. For example, if you want to provide a fire resistance time of 60 minutes, you should ensure that the finishing layer 4 is 0.6 mm / min × 60 = 36 mm thick. On the other hand, if the finishing layer 4 is made too thick, the burning time as a combustible material will increase, and the thermal impact on the load-bearing part 2 will be greater, so it is preferable that the upper limit of the thickness of the finishing layer 4 is the value mentioned above.

[0032] Structural materials with a roughly rectangular cross-section are prone to fire-resistant weaknesses in the event of a fire, as the two surfaces flanking the corner are exposed to flames, making them susceptible to high temperatures (e.g., 300°C to 400°C). In this respect, the fire-resistant structural material 1A of this embodiment has a heat-insulating member 3a at the corner of the fire-stopping layer 3, which has a thermal conductivity of 0.06 W / (m·K) or less. As a result, heat conduction is slow, and it has higher fire resistance than the wood portion 3b. Furthermore, the wood constituting the finishing layer 4 of the fire-resistant structural material 1A of this embodiment is thick and dense, which allows for more time before the heat of the fire is transferred to the load-bearing portion 2. Therefore, the fire-resistant structural material 1A of this embodiment can satisfy the required fire resistance performance while keeping the thickness of the fire-stopping layer 3 low.

[0033] [Method for manufacturing fire-resistant structural materials] The method for manufacturing the fire-resistant structural material 1B shown in Figure 4 will be explained. Fire-resistant structural material 1B specifically shows the shapes of the members that make up each part, and is essentially the same as fire-resistant structural material 1A. Although not shown in Figure 4, all the wood used (load-bearing part 2, fire-stopping layer materials 3b1-3b4, and finishing layer materials 4a1-4a4) is laminated timber. In addition, fire-stopping layer materials 3b1-3b4 are pre-treated with a flame-retardant agent.

[0034] First, a long piece of lumber with a roughly square cross-section is prepared as the load-bearing section 2 and laid on the frame. As shown in Figure 2, plate-shaped fire-stopping layer materials 3b1 to 3b4 are glued to each of the four faces of the load-bearing section 2. Here, as shown in Figure 4, the names of the members, clockwise from the top of the illustration, are the first fire-stopping layer material 3b1, the second fire-stopping layer material 3b2, the third fire-stopping layer material 3b3, and the fourth fire-stopping layer material 3b4. Next, the first finishing layer material 4a1 and the third finishing layer material 4a3, which are the wood that constitutes the finishing layer, are glued to the outer faces of the first fire-stopping layer material 3b1 and the third fire-stopping layer material 3b3, which are opposite each other on either side of the load-bearing section 2.

[0035] Then, at least one of the following is trimmed so that the outer surface of the second fire-stopping layer 3b2 (which does not have a finishing layer bonded to it), the end of the first finishing layer 4a1, and the end of the third finishing layer 4a3 are located in the same plane. Similarly, at least one of the following is trimmed so that the outer surface of the fourth fire-stopping layer 3b4 (which does not have a finishing layer bonded to it), the opposite end of the first finishing layer 4a1, and the opposite end of the third finishing layer 4a3 are located in the same plane. This completes the first intermediate structure 10A shown in Figure 2 (groove formation process). In the first intermediate structure 10A, grooves 7 are formed at four locations corresponding to the corners of the fire-stopping layer: at the edges of the fire-stopping layer materials (3b1, 3b3) to which the finishing layer materials (4a1, 4a3) are bonded, at the edges of the fire-stopping layer materials (3b2, 3b4) to which the finishing layer materials are not bonded, and on the inner surface of the finishing layer materials (4a1, 4a3).

[0036] Next, four axially molded heat-insulating members 3a are prepared. As shown in Figure 3, the heat-insulating members 3a are pressed into the four grooves 7 of the first intermediate structure 10A (heat-insulating section formation step). It is preferable to apply adhesive to the inner surface of the grooves 7 before this placement. If the heat-insulating members 3a are made of a rigid material, they may obstruct the surface and protrude from the flat plane prepared in the previous step. If the cross-sectional shape is made smaller to avoid this, the grooves 7 cannot be properly filled with the heat-insulating members 3a. Therefore, it is desirable that the heat-insulating members 3a are made of an elastic material that can be crushed when force is applied. If the heat-insulating members 3a are elastic, it is preferable that they are molded to be larger than the inner diameter of the grooves 7. This allows the heat-insulating members 3a to be filled into the grooves 7 without any gaps. This completes the second intermediate structure 10B. Furthermore, if, due to the length of the fire-resistant structural material 1B in the axial direction, one heat-insulating member 3a cannot completely fill one groove 7, multiple heat-insulating members 3a may be used in a continuous manner in the axial direction.

[0037] Next, the second finishing layer 4a2 is glued to the outer surface of the second fire-stopping layer 3b2, the end of the first finishing layer 4a1, the end of the third finishing layer 4a3, and the heat-insulating members 3a, 3a. Similarly, the fourth finishing layer 4a4 is glued to the outer surface of the fourth fire-stopping layer 3b4, the opposite end of the first finishing layer 4a1, the opposite end of the third finishing layer 4a3, and the heat-insulating members 3a, 3a. Then, at least one of the outer surface of the first finishing layer 4a1, the end of the second finishing layer 4a2, and the end of the fourth finishing layer 4a4 is trimmed so that they are flush. Similarly, at least one of the outer surface of the third finishing layer 4a3, the opposite end of the second finishing layer 4a2, and the opposite end of the fourth finishing layer 4a4 is trimmed so that they are flush. This completes the fire-resistant structural material 1B shown in Figure 4 (coating process). This cutting process may be omitted if not necessary. In addition, the opposing pair of finishing layer materials 4a2 and 4a4 may be intentionally extended to create a shape in which each end protrudes, in which case the cutting process is also unnecessary.

[0038] In this manufacturing method, the placement of the heat-insulating member 3a is made easy by using a procedure that includes a first intermediate structure 10A having a groove 7. Furthermore, since the heat-insulating member 3a is bonded on three surfaces within the groove 7, the risk of it peeling off during subsequent manufacturing processes is reduced. In addition, when bonding the second finishing layer material 4a2 and the fourth finishing layer material 4a4 in the second intermediate structure 10B, the outer surface of the second fire-stopping layer material 3b2 or the fourth fire-stopping layer material 3b4, the end of the first finishing layer material 4a1, and the end of the third finishing layer material 4a3 are all covered simultaneously, resulting in high work efficiency. As a result, it becomes easy to manufacture fire-resistant structural materials in which a different material from wood is placed at the corners of the fire-stopping layers.

[0039] <Second Embodiment> A second embodiment of the present invention will now be described. The difference between the fire-resistant structural material 1C of the second embodiment shown in Figure 5 and the fire-resistant structural material 1A of the first embodiment is that a cavity 3c and a foamed fire-resistant layer 3d are present at the corners of the fire-stopping layer. The following explanation will focus on this point.

[0040] As shown in Figure 5, a cavity 3c is formed at the corner of the fire-stopping layer 3 between the ends of two adjacent wooden sections 3b, 3b and the inner surface of the finishing layer 4. Within the cavity 3c, a sheet-like foamed fire-resistant layer 3d is attached to the ends of the wooden sections 3b, 3b. Near the corner of the load-bearing section 2, the two foamed fire-resistant layers 3d fill the ends of the wooden sections 3b, 3b without gaps, with the thickness of one layer in contact with the surface of the other. The thickness of the foamed fire-resistant layer 3d may be 1 mm to 5 mm, or 2 mm to 4 mm. Although Figure 5 shows an embodiment in which independent sheet-like foamed fire-resistant layers 3d are attached to the ends of the two wooden sections 3b, 3b, a single foamed fire-resistant layer 3d sheet may also be folded and attached at a right angle as much as possible.

[0041] The foamed refractory layer 3d is a layer composed of a refractory agent that has foaming properties. Ammonium polyphosphate is an example of such a refractory agent.

[0042] The method for forming the foamed fire-resistant layer 3d involves laminating a pre-formed sheet onto the edges of the wooden section 3b.

[0043] The thickness of the foamed fire-resistant layer 3d varies depending on the required fire resistance time. For example, if 60-minute fire resistance is required, the thickness of the foamed fire-resistant layer 3d is 1 mm or more. This thickness may be 1.5 mm to 3.0 mm, or 2.0 mm to 2.5 mm. If 90-minute fire resistance is required, the thickness of the foamed fire-resistant layer 3d is preferably 2 mm or more, but may be 2.5 mm to 6.0 mm, or 3.0 mm to 5.0 mm. Even if 90-minute fire resistance is required, it is also possible to achieve the same result by using the same thickness for the foamed fire-resistant layer 3d as for 60-minute fire resistance and instead increasing the thickness of the finishing layer 4.

[0044] The foamed fire-resistant layer 3d covers at least 40% of the surface area of ​​the inner surface of the hollow wood (here, the ends of two adjacent wood sections 3b, 3b and the inner surface of the finishing layer 4). This percentage (hereinafter referred to as the "coverage percentage") may be at least 45%, at least 50%, or at least 55%. For example, if the thickness of the wood section 3b is 15 mm and the thickness of the foamed fire-resistant layer 3d is 1.5 mm, the percentage is (12 × 2 + 1.5 × 2) / (12 × 4) = 0.56, which is 56%. In this calculation, the surface area of ​​the wood is replaced with the length of the line segment in the cross-sectional view.

[0045] Structural materials with a roughly rectangular cross-section are prone to becoming fire-resistant weak points in fire because the two surfaces flanking the corner are exposed to flames and become extremely hot. In this respect, the fire-resistant structural material 1C of this embodiment has a thick and dense wood that makes up the finishing layer, resulting in high fire resistance of the finishing layer. Furthermore, when heated, the foamed fire-resistant layer 3d expands toward the cavity 3c, forming an insulating layer, thus increasing its insulating properties. For these reasons, the fire-resistant structural material 1C of this embodiment can reduce the thickness of the fire-stopping layer.

[0046] Furthermore, in the fire-resistant structural material 1C, considering the manufacturing procedure, the foamed fire-resistant layer 3d is provided on the end grain of the wooden part 3b within the cavity 3c, making it easier to manufacture the fire-resistant structural material 1C compared to when the foamed fire-resistant layer 3d is provided on other parts of the cavity 3c.

[0047] The fire-resistant structural material 1C of the second embodiment may take other forms, as long as the coverage ratio is at least 40%. For example, as shown in Figure 6(A), the foamed fire-resistant layer 3d does not necessarily need to be provided over the entire end surface of the wood portion 3b. Considering ease of manufacture, the foamed fire-resistant layer 3d may not be provided near the corners of the load-bearing portion 2, leaving some of the end surfaces of the wood portions 3b, 3b exposed. Even in this case, the foam generated by heating will sufficiently reach the exposed end surfaces.

[0048] Furthermore, as shown in Figure 6(B), the fire-resistant structural material 1C may have the foamed fire-resistant layer 3d provided on the inner surface of the finishing layer 4 in the cavity 3c, rather than on the ends of the wood parts 3b, 3b. In this case, the foamed fire-resistant layer 3d must be positioned relative to the finishing layer 4, which increases the difficulty of manufacturing. However, because the foamed fire-resistant layer 3d is close to the finishing layer 4, the temperature rises quickly, and it is possible to expect it to foam up at an early stage and exhibit thermal insulation properties.

[0049] Furthermore, as shown in Figure 6(C), the fire-resistant structural material 1C may have a form in which the width of the wooden parts 3b, 3b is shortened so that the cavity 3c is L-shaped in cross-section. In this case, it is preferable that the distance at which the ends of the two wooden parts 3b, 3b are set back from the apex of the load-bearing part 2 is the same for both. In this form, the load-bearing part 2, which must not be carbonized, will face the cavity 3c (through the foamed fire-resistant layer 3d), but the volume of the cavity 3c and the area of ​​the foamed fire-resistant layer 3d will be larger, resulting in high thermal insulation.

[0050] Furthermore, as shown in Figure 6(D), the fire-resistant structural material 1C may have a configuration in which one end of adjacent wooden sections 3b, 3b covers a portion of the end of the other. In this configuration, the wooden section 3b that covers a portion of the end also covers a portion of the end of the other wooden section 3b at its other end. In this configuration, the end of the wooden section 3b that has a portion of its end covered is also partially covered on the opposite end by another wooden section 3b. In this case, the corner of the load-bearing section 2 is completely covered by the wooden sections 3b, 3b, thus providing strong protection to the corner of the load-bearing section 2. In this case, the tolerance for misalignment in the configuration of the foamed fire-resistant layer and the bonding of the members becomes larger, making it easier to manufacture the fire-resistant structural material 1C.

[0051] Although preferred embodiments of the present invention have been described above, the present invention is not limited in any way to the above embodiments. For example, in the first embodiment, an example of an improved heat insulation member 3a made of rock wool or a material containing resin was shown, but a part of the improved heat insulation member may be air. If the entire improved heat insulation member is air, the fire resistance tends to be inferior, so it is preferable to avoid a configuration in which the entire improved heat insulation member is air. Furthermore, in a configuration in which a part of the improved heat insulation member is air, it is preferable that 40% or more of the inner surface of the wood forming the cavity is not exposed to the cavity (for example, covered with a foamed fire-resistant layer). In addition, the wood portion 3b constituting the fire-stopping layer 3 may be made of a non-combustible material other than wood (gypsum board, calcium silicate board, etc.).

[0052] Furthermore, for example, in the second embodiment, the foamed fire-resistant layer 3d is in the form of a sheet. However, as a method for forming the foamed fire-resistant layer 3d, if the fire-resistant agent is solid, for example, a method may be adopted in which the fire-resistant agent is dispersed in a resin to prepare a coating solution, and this solution is applied to the end surface of the wood part 3b. Methods for curing the resin include air drying, heating, ultraviolet irradiation, etc.

[0053] The present invention also includes the following embodiments. ·[1] A load-bearing section made of wood with a roughly rectangular cross-section, A fire-stopping layer surrounding the load-supporting portion, having corners, A fire-resistant structural material comprising a finishing layer made of wood that surrounds the aforementioned fire-stopping layer, In a cross-sectional view, the corner of the fire-stopping layer is hollow, and at least 40% of the inner surface of the wood forming the hollow is covered with a foamed fire-resistant layer. The fire-stopping layer consists of wood in parts other than the cavity. The thickness of the aforementioned fire-stopping layer is 10 mm or more and 40 mm or less. The thickness of the aforementioned finishing layer is 40 mm or more. The density of the wood constituting the aforementioned finishing layer is 350 kg / m³ 3 That concludes the explanation of fire-resistant structural materials. ·[2] The fire-resistant structural material described in [1] above, wherein the thickness of the finishing layer is 70 mm or more. ·[3] The density of the wood constituting the aforementioned fire-stopping layer is 400 kg / m³ 3 A fire-resistant structural material as described in [1] above, which is less than [1]. ·[4] The fire-resistant structural material described in [1] above, wherein the foamed fire-resistant layer is provided on the end grain of the wood constituting the fire-stopping layer. ·[5] The fire-resistant structural material according to [1] above, wherein at the corner of the fire-stopping layer, both ends of the fire-stopping layer extending along the first side of the substantially rectangular shape cover a portion of the end grain of the wood constituting the fire-stopping layer extending along the second side and the third side perpendicular to the first side, respectively. ·[6] The fire-resistant structural material described in [1] above, wherein the inner surface of the wood forming the cavity is composed only of the fire-stopping layer and the finishing layer. [Examples]

[0054] The present invention will be explained in more detail below with reference to experimental examples.

[0055] The materials used are as follows: • Cedar wood…Laminated timber. Density is approximately 350 kg / m³.3 . When used to construct a fire-stopping layer, use flame-retardant treated material (amount of flame-retardant treatment agent fixed = 156 kg / m 3 The substance is injected to make it flame-retardant. Larch wood…Laminated timber. Density is approximately 500 kg / m³. 3 • Adhesive: Resorcinol-based resin adhesive

[0056] <60-minute fire resistance test> [Experimental Example 1] (Preparation of test specimens) A fire-resistant structural material with the shape shown in Figure 4 was fabricated. • Core material (load-bearing section): 300mm square cedar wood. • Fire-stopping layer: 15mm thick cedar wood. • Finishing layer: 45mm thick larch wood. The test specimen was prepared using the first intermediate structure 10A shown in Figure 2 and the second intermediate structure 10B shown in Figure 3. As the thermal insulation improving member, axially molded rock wool (with a thermal conductivity of approximately 0.038 W / (m·K) at room temperature) was used.

[0057] (Test method) The test specimen was heated in a refractory furnace for 60 minutes so that the temperature around its perimeter followed the ISO 834 curve.

[0058] (Judgment method) The results of the fire resistance test were determined by visual inspection. It is known that wood ignites or carbonizes at temperatures around 260°C. • Visual inspection: The surface of the load-bearing area was visually inspected to ensure that no areas were carbonized. If no areas were carbonized, it was considered "good," and if any area was carbonized, it was considered "bad."

[0059] (result) The fire resistance test results were "good." The composition of the fire-resistant structural material and the test results are shown in Table 1.

[0060] [Experimental Example 2] The test specimen was prepared in the same manner as in Experimental Example 1, except that the material for the improved insulation section was changed to phenolic resin foam (thermal conductivity at room temperature is 0.019 W / (m·K)), and a fire resistance test was conducted. The results are shown in Table 1.

[0061] [Experimental Example 3] We created a structural material that does not have any special structures at the corners of the fire-stopping layer. In other words, the entire fire-stopping layer is made of wood. • Core material (load-bearing section): 300mm square cedar wood. • Fire-stopping layer: 10mm thick cedar wood. • Finishing layer: 50mm thick larch wood. A test specimen was prepared by laminating a fire-stopping layer around the core material and a finishing layer around the fire-stopping layer. A fire resistance test was conducted in the same manner as in Experimental Example 1. The results are shown in Table 1.

[0062] [Experimental Example 4] The test specimens were prepared in the same manner as in Experimental Example 3, except that the thickness of the fire-stopping layer was set to 12 mm and the thickness of the finishing layer was set to 48 mm. A fire resistance test was then conducted in the same manner as in Experimental Example 1. The results are shown in Table 1.

[0063] [Experimental Example 5] The test specimens were prepared in the same manner as in Experimental Example 3, except that the thickness of the fire-stopping layer was set to 15 mm and the thickness of the finishing layer was set to 45 mm. A fire resistance test was then conducted in the same manner as in Experimental Example 1. The results are shown in Table 1.

[0064] [Experimental Example 6] A fire-resistant structural material with the shape shown in Figure 5 (but without a foamed fire-resistant layer) was fabricated. • Core material (load-bearing section): 300mm square cedar wood. • Fire-stopping layer: 12mm thick cedar wood. • Finishing layer: 48mm thick larch wood. A test specimen was prepared via the first intermediate structure 10A shown in Figure 2, and a fire resistance test was conducted in the same manner as in Experimental Example 1. The results are shown in Table 1.

[0065] [Experimental Example 7] A fire-resistant structural material with the shape shown in Figure 5 was fabricated. • Core material (load-bearing section): 300mm square cedar wood. • Fire-stopping layer: 12mm thick cedar wood. • Finishing layer: 48mm thick larch wood. • Foamed fire-resistant layer: A sheet made of ammonium polyphosphate; 1.5 mm thick. A test specimen was prepared via the first intermediate structure 10A shown in Figure 2, and a fire resistance test was conducted in the same manner as in Experimental Example 1. The results are shown in Table 1.

[0066] [Experimental Example 8] The test specimen was prepared in the same manner as in Experimental Example 7, except that the thickness of the finishing layer was set to 38 mm, and the fire resistance test was conducted in the same manner as in Experimental Example 1. The results are shown in Table 1.

[0067] [Experimental Example 9] A fire-resistant structural material with the shape shown in Figure 6(D) was fabricated. In Figure 6(D), the overlap of one wooden section 3b covering the end grain of the adjacent wooden section 3b was set to 5 mm. A test specimen was prepared and a fire resistance test was conducted in the same manner as in Experimental Example 1. The results are shown in Table 1.

[0068] <90-minute fire resistance test> [Experimental Example 10] The test specimens were prepared in the same manner as in Experimental Example 7, except that the core material was 150 mm square, the fire-stopping layer thickness was 15 mm, and the finishing layer thickness was 65 mm, and a fire resistance test was conducted. The results are shown in Table 1.

[0069] [Experimental Example 11] The test specimen was prepared in the same manner as in Experimental Example 10, except that the thickness of the finishing layer was set to 85 mm, and a fire resistance test was conducted. The results are shown in Table 1. [Table 1] [Industrial applicability]

[0070] This invention can be used in wooden buildings. [Explanation of Symbols]

[0071] 1A, 1B, 1C... Fire-resistant structural material, 2... Load-bearing part, 3... Fire-stopping layer, 3a... Heat insulation improvement member (heat insulation improvement part), 3b... Wood part, 3b1... First fire-stopping layer material, 3b2... Second fire-stopping layer material, 3b3... Third fire-stopping layer material, 3b4... Fourth fire-stopping layer material, 3c... Cavity, 3d... Foamed fire-resistant layer, 4... Finishing layer, 4a1... First finishing layer material, 4a2... Second finishing layer material, 4a3... Third finishing layer material, 4a4... Fourth finishing layer material, 7... Groove, 10A... First intermediate structure, 10B... Second intermediate structure.

Claims

1. A load-bearing section made of wood with a roughly rectangular cross-section, A fire-stopping layer surrounding the load-supporting portion, having corners, A fire-resistant structural material comprising a finishing layer made of wood that surrounds the aforementioned fire-stopping layer, In a cross-sectional view, the corner of the fire-stopping layer is hollow, and at least 40% of the inner surface of the wood forming the hollow is covered with a foamed fire-resistant layer. The aforementioned fire-stopping layer consists of wood in parts other than the aforementioned cavity. The thickness of the aforementioned fire-stopping layer is 10 mm or more and 40 mm or less. The thickness of the aforementioned finishing layer is 40 mm or more. The density of the wood constituting the aforementioned finishing layer is 350 kg / m³ ３ That concludes the explanation of fire-resistant structural materials.

2. The fire-resistant structural material according to claim 1, wherein the thickness of the finishing layer is 70 mm or more.

3. The density of the wood constituting the aforementioned fire-stopping layer is 400 kg / m³ ３ A fire-resistant structural material according to claim 1, which is less than [amount missing].

4. The fire-resistant structural material according to claim 1, wherein the foamed fire-resistant layer is provided on the end grain of the wood constituting the fire-stopping layer.

5. The fire-resistant structural material according to claim 1, wherein at the corner of the fire-stopping layer, both ends of the fire-stopping layer extending along the first side of the substantially rectangular shape cover a portion of the end grain of the wood constituting the fire-stopping layer extending along the second side and the third side perpendicular to the first side, respectively.

6. The fire-resistant structural material according to claim 1, wherein the inner surface of the wood forming the cavity is composed only of the fire-stopping layer and the finishing layer.

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