JP6936564B2 - Refractory wood material - Google Patents

Description

The present invention relates to a refractory wood member suitable for use as a building structural member such as a column or a beam, and more particularly to a refractory wood member having improved fire resistance performance at a corner portion in a cross section of the member.

Conventionally, when constructing a structure with wooden columns and beams made of wood-based material, the wood-based material is vulnerable to fire, so if necessary, the wood-based material is covered with a heat insulating material to suppress the temperature rise due to fire heating. Measures are being taken. When a fire-resistant wood member such as a wooden pillar or a wooden beam having a square cross section whose surface layer is covered with a heat insulating material such as gypsum board receives fire heating, the inner wood part becomes hot due to heat conduction through the heat insulating material of the surface layer.

In particular, as shown in FIG. 7, in the fire-resistant wood member in which the wood core material 1 which is the load support portion is covered with the plaster board 2, the wood pillar having the square cross section of (1) is heated by the heat F from the surroundings due to the fire. In the case of a wooden beam with a square cross section provided under the floor 4 in (2), the amount of heat input to the two corners 3 at the lower end is the side surface. It is larger than 5 (the amount of heat input per unit area with respect to 5), and the temperature is higher than that of the side surface portion 5. Since these corners 3 are easily heated from two directions at right angles in a cross-sectional view, the thermal deterioration of the corners 3 becomes a weak point in fire resistance such as load bearing performance of wood members. .. That is, when the corner portion 3 exceeds the ignition temperature of the wood earlier than the side surface portion 5 and starts combustion, the fire spreads to the inside or the side surface portion 5 which has not yet reached the ignition temperature, and the member cross section is damaged due to carbonization and ashing. Inviting, there is a risk that the structure will collapse due to a decrease in the bearing capacity of the members.

On the other hand, fire-resistant wood members that have been devised in various ways in order to secure the fire-resistant performance of the corners are known (see, for example, Patent Documents 1 to 4).

Japanese Unexamined Patent Publication No. 2012-136939 Japanese Patent No. 4871660 Japanese Unexamined Patent Publication No. 2015-129431 JP-A-2015-061969

However, in the above-mentioned conventional structure, in order to improve the fire-resistant performance of the corner portion, a material having high fire-resistant performance is specially used for the portion, or the entire member is covered with the thickness of the fire-resistant coating required for the corner portion. As a result, the coating layer became thicker. Therefore, there are problems that the manufacturing method of the refractory wood member becomes complicated and the coating layer becomes thick, so that the cost increases and the cross section of the member also becomes large.

Therefore, there has been a demand for the development of a refractory wood member capable of slimming the cross section of the member while having the same structural performance as the conventional one.

The present invention has been made in view of the above, and an object of the present invention is to provide a refractory wood member capable of slimming the cross section of the member.

In order to solve the above-mentioned problems and achieve the object, the fire-resistant wood member according to the present invention is a fire-resistant wood member having a core material made of a wood material that supports a load, and is at least a core material. It is characterized in that a high thermal conductive material having a thermal conductivity higher than that of the core material is provided in a predetermined region including the surface of the corner portion in the cross section.

Further, the other fire-resistant wood member according to the present invention further includes a burn-stop layer or a finishing material provided on the outside of the core material in the above-described invention, and the high thermal conductive material includes a core material and a burn-stop layer or a finishing material. It is provided between the two, and is characterized by having a higher thermal conductivity than a burnout layer or a finishing material.

Further, in the other refractory wood member according to the present invention, in the above-mentioned invention, the second burn-stop layer provided on the outside of the core material and the first burn-stop layer provided on the outside of the second burn-stop layer are further added. The high thermal conductive material is provided between the second refractory layer and the first refractory layer, and is characterized by having a higher thermal conductivity than the second refractory layer and the first refractory layer.

Further, in the above-described invention, the other fire-resistant wood member according to the present invention further includes a burn-stop layer provided on the outside of the core material and a finishing material provided on the outside of the burn-stop layer. , Provided between the core material and the burn-out layer, or at least one of the burn-off layer and the finishing material, has a higher thermal conductivity than the core material and the burn-off layer, or the burn-off layer and the finishing material. It is characterized by being large.

According to the fire-resistant wood member according to the present invention, it is a fire-resistant wood member having a core material made of a wood material that supports a load, and at least in a predetermined region including the surface of a corner portion in the cross section of the core material. Since a high thermal conductive material having a higher thermal conductivity than the core material is provided, it is possible to suppress the temperature rise of the corner portion, which is a weak point in terms of fire resistance, and to significantly improve the fire resistance performance of the corner portion. Therefore, even if the member is made thinner, the structural performance equal to or higher than that of the conventional one can be ensured, and the cross section of the member can be slimmed down and the cost can be reduced. Further, by using this refractory wood member for pillars, beams, etc. in the room, the openness of the room space is enhanced, and the room can be effectively utilized.

Further, according to another fire-resistant wood member according to the present invention, a burn-stop layer or finishing material provided on the outside of the core material is further provided, and the high thermal conductive material is provided between the core material and the burn-stop layer or finishing material. Since it is provided and has a higher thermal conductivity than the burn-off layer or the finishing material, the effect that the high thermal conductive material can suppress the temperature rise of the corners, which is a weak point in terms of fire resistance, and can significantly improve the fire resistance performance of the corners. Play. Further, the non-burning layer can suppress heat transfer to the core material due to a fire and prevent carbonization and combustion of the core material. Further, the finishing material can give a wood texture to the outside of the core material.

Further, according to another refractory wood member according to the present invention, a second burn-stop layer provided on the outside of the core material and a first burn-stop layer provided on the outside of the second burn-stop layer are further provided to provide high heat. The conductive material is provided between the second burn-stop layer and the first burn-stop layer, and has a higher thermal conductivity than the second burn-stop layer and the first burn-stop layer. It has the effect of suppressing the temperature rise of the corners and significantly improving the fire resistance performance of the corners. Further, the second burn-off layer and the first burn-off layer can suppress heat transfer to the core material due to a fire and prevent carbonization and combustion of the core material.

Further, according to another fire-resistant wood member according to the present invention, a burn-stop layer provided on the outside of the core material and a finishing material provided on the outside of the burn-stop layer are further provided, and the high thermal conductive material is a core material. Since it is provided between the and the stop-burn layer or at least one of the stop-burn layer and the finishing material, it has a higher thermal conductivity than the core material and the stop-burn layer, or the stop-burn layer and the finishing material. The high thermal conductive material has the effect of suppressing the temperature rise of the corners, which is a weak point in terms of fire resistance, and significantly improving the fire resistance performance of the corners. Further, the non-burning layer suppresses the transfer of heat to the core material due to a fire, prevents carbonization and combustion of the core material, and the finishing material can impart a wood texture to the outside of the core material.

1 (1) is a cross-sectional view showing the first embodiment of the refractory wood member according to the present invention, (2) is an enlarged view of a corner portion of (1), and (3) is a cross-sectional view showing a comparative example of the present invention. FIG. 6 (4) is an enlarged view of a corner portion of (3). FIG. 2 (1) is a cross-sectional view showing the second embodiment of the refractory wood member according to the present invention, (2) is an enlarged view of a corner portion of (1), and (3) is a cross-sectional view showing a comparative example of the present invention. FIG. 6 (4) is an enlarged view of a corner portion of (3). FIG. 3 is a diagram showing a change over time in the temperature at the corner of the core material (in the case of a core material having a 10 cm square). FIG. 4 is a diagram showing a change with time (in the case of a 20 cm square core material) of the core material corner temperature. FIG. 5 is a diagram showing the temperature distribution (in the case of a 10 cm square core material) on the surface of the core material (positions symmetrical from the corner to the side surface), (1) is 30 minutes after the start of heating, and (2). Is 60 minutes. FIG. 6 is a diagram showing the temperature distribution (in the case of a 20 cm square core material) on the surface of the core material (positions symmetrical from the corner to the side surface), (1) is 30 minutes after the start of heating, and (2). Is 60 minutes. FIG. 7 is an example of a conventional fire-resistant wood member that receives fire heating, (1) is a horizontal cross-sectional view of a wood pillar, and (2) is a vertical cross-sectional view of a wood beam.

Hereinafter, embodiments of the refractory wood member according to the present invention will be described in detail with reference to the drawings, taking the case of wood pillars as an example. The present invention is not limited to this embodiment.

(Embodiment 1)
First, Embodiment 1 of the present invention will be described.
As shown in FIGS. 1 (1) and 1 (2), the refractory wood member 100 according to the present embodiment includes a core material 10 made of a wood material that supports a load and a high heat conductive material provided outside the core material 10. It is a wooden pillar including a 12 and a burn-off layer 14 provided on the outside of the high heat conductive material 12. The shape of the cross section of the core material 10 and the entire member including the core material 10 is a regular quadrangular shape (polygonal shape).

The core material 10 is made of laminated lumber (wood material) that supports a load. As the core material 10, for example, a general laminated lumber made of sugi, larch, or the like can be used. The thickness (distance between opposite sides) of the core material 10 can be appropriately adjusted according to the intended use, but can be, for example, about 450 mm.

The high thermal conductive material 12 is made of a material having a higher thermal conductivity than the adjacent core material 10 and the burn-off layer 14. When the non-burning layer 14 is composed of a heat insulating material such as a gypsum board, examples of the material having a higher thermal conductivity than the heat insulating material and the wood material include a metal film such as a general steel material, a stainless steel material, and an aluminum alloy, and a metal plate. The high thermal conductive material 12 can be made of such a material. Further, in the example of the figure, the case where the high thermal conductive material 12 is provided on the entire circumference of the core material 10 is shown, but the present invention is not limited to this. That is, in order to achieve the object of the present invention of suppressing the temperature rise of the corner portion 16 (corner portion), a high thermal conductive material is formed on the surface of the core material in a predetermined region including the corner portion 16 in at least the cross section of the core material 10. 12 may be provided. In this case, the high thermal conductive material 12 may be provided in an L shape so that the corner portion 16 becomes a bent portion, and the extension measured from the corner portion 16 is, for example, 1/1 of the length of one side of the core material 10. It may be about 4.

The non-flammable layer 14 is a coating layer having fire resistance, for example, an endothermic and / or heat insulating inorganic material, a non-flammable non-flammable material, or a nonflammable material that foams when it receives heat and significantly increases its thickness to insulate. It can be made of a material such as a refractory sheet or a refractory film that exhibits properties. The non-burning layer 14 has a function of preventing heat transfer to the adjacent inner high thermal conductive material 12 and core material 10 in the event of a fire, and does not carbonize or burn the core material 10 to the core material 10. It exerts the effect of suppressing heat conduction. When the burn-off layer 14 is made of an inorganic material, a board-like material such as a reinforced gypsum board, a gypsum board, or a calcium silicate board can be used. Further, the thickness thereof can be appropriately adjusted according to the application. The thicker the thickness, the better the effect of suppressing heat conduction. These boards may be stacked to a predetermined thickness. Here, materials such as reinforced gypsum board, gypsum board, and calcareous board (calcium silicate board) are suitable as the burn-off layer 14 because they can be obtained at an extremely low price and have high heat insulating properties and endothermic properties. .. When the non-combustible layer 14 is made of a non-combustible material, for example, non-combustible wood obtained by impregnating wood with a chemical such as boric acid and treating it with non-combustible material can be used. The thickness of the burn-off layer 14 can be appropriately adjusted according to the intended use, but is preferably about 15 mm to 45 mm, more preferably about 30 mm, for example. When the refractory layer 14 is made of a material such as the above-mentioned refractory sheet or refractory film, its thickness can be appropriately adjusted according to the application, but is preferably about 1 mm to 12 mm, for example. , 1.5 mm to 6 mm is more preferable.

The operation of the refractory wood member 100 configured as described above will be described.
1 (1) and 1 (2) show the present embodiment, and FIGS. 1 (3) and 1 (4) show comparative examples. A comparative example is a conventional structure including only a core material 10 and a burn-out layer 14. As shown in FIGS. 1 (4) and 1 (2), the thicknesses of the burn-off layer 14 of the comparative example and the present embodiment are set to t ₀ and t _s , respectively, and the corner portion 16 is heated by the heat F from the surroundings due to the fire. Let the heat energy flowing into (hatched portion) be E ₀ and E _s , and the temperature of the corner portion 16 (hatched portion) be T ₀ and T _s .

Here, as shown in FIG. 1 (2), the high thermal conductive material 12 of the present embodiment acts to disperse the thermal energy H concentrated in the corner portion 16 in the side surface portion central direction G. _{Therefore, assuming} that the thickness of the burn-out layer 14 is t ₀ = t _{s, the thermal energy E 0} > E _s flowing into the corner portion 16 and the temperature T ₀ > T _s . Therefore, according to the present embodiment, it is possible to suppress the temperature rise of the corner portion 16 as compared with the comparative example.

As described above, according to the fire-resistant wood member 100, the high heat conductive material 12 is provided on the surface of the core material 10 including the corner portion 16 which is a weak point in terms of fire resistance due to the concentration of heat energy. By dispersing the heat energy concentrated on the corner portion 16 in the direction along the surface of the core material, the temperature rise of the corner portion 14 can be suppressed and the fire resistance performance thereof can be remarkably improved. Therefore, even if the member is made thinner, the structural performance equal to or higher than that of the conventional one can be ensured, and the cross section of the member can be slimmed down and the cost can be reduced. Further, by using the refractory wood member 100 for pillars (or beams) in the room, the openness of the room space is enhanced, and the room can be effectively utilized.

In addition, in the above-described embodiment, a finishing material for imparting a wood texture to the outside of the burn-off layer 14 may be further provided. Alternatively, instead of the burn-off layer 14, a finishing material for imparting a wood texture may be provided on the outside of the core material 10. With this finishing material, the outer surface of the refractory wood member 100 can have a wood texture or a wood grain appearance. As the finishing material, it is desirable to use a wood material such as wood or laminated wood for cosmetics in order to reduce costs, but a building finishing material such as cloth may be used. The thickness of the finishing material is preferably, for example, about 3 mm to 30 mm, but of course, it may be thinner than this.

Further, in the above embodiment, the burn-stop layer 14 may be composed of two or more burn-stop layers having different actions and functions. Even in this way, it is possible to obtain the same effects as described above.

(Embodiment 2)
Next, Embodiment 2 of the present invention will be described.
As shown in FIGS. 2 (1) and 2 (2), the refractory wood member 200 according to the present embodiment has a core material 10 made of a wood material that supports a load and a second burn provided outside the core material 10. It is a wooden column including a stop layer 14B, a high heat conductive material 12 provided on the outside thereof, and a first burn stop layer 14A provided on the outside of the high heat conductive material 12.

The high thermal conductive material 12 is made of a material having a higher thermal conductivity than the adjacent first stop layer 14A and second stop layer 14B. Since the high thermal conductive material 12 is the same as the member described in the first embodiment, detailed description thereof will be omitted.

Since the core material 10, the second stop layer 14B, and the first stop layer 14A are the same as the core material 10 and the stop layer 14 described in the first embodiment, detailed description thereof will be omitted.

The second burn-off layer 14B and the first burn-off layer 14A are made of the same material in the present embodiment, but the present invention is not limited to this, and are made of different materials having different actions and functions. It doesn't matter. In addition, a finishing material for imparting a wood texture to the outside of the first burn-off layer 14A may be further provided. Further, in addition to the second burn-stop layer 14B and the first burn-stop layer 14A, one or more burn-stop layers may be provided. In this case, the refractory wood member as a whole has three or more layers (plurality of layers) of stop-burning layers. Further, a finishing material for imparting a wood texture to the outside of the outermost burn-off layer may be provided.

The operation of the refractory wood member 200 configured as described above will be described.
2 (1) and 2 (2) show the present embodiment, and FIGS. 2 (3) and 2 (4) show comparative examples. A comparative example is a conventional structure including only a core material 10 and a burn-out layer 14. As shown in FIGS. 2 (4) and 2 (2), the thicknesses of the burn-stop layer 14 of the comparative example, the first burn-stop layer 14A and the second burn-stop layer 14B of the present embodiment are t ₀ and t _{s1, respectively.} , T _s2, and the heat energy flowing into the corner portion 16 (hatched portion) due to the heating F from the surroundings due to the fire is E ₀ , E _s , and the temperature of the corner portion 16 (hatched portion) is T ₀ , T _s . do.

Here, as shown in FIG. 2 (2), the high thermal conductive material 12 of the present embodiment acts to disperse the thermal energy H concentrated in the corner portion 16 in the side surface portion central direction G. Therefore, if the thickness of the burn-out layer 14 is t ₀ = t _s1 + t _{s2 , the thermal energy E 0} > E _s flowing into the corner portion 16 and the temperature T ₀ > T _s . Therefore, according to the present embodiment, it is possible to suppress the temperature rise of the corner portion 16 as compared with the comparative example. It should be noted that the more heat is blocked outside the high heat conductive material 12, the smaller the inflowing heat energy is, so that the effect of dispersing the heat energy from the corner portion 16 is higher. Therefore, it is preferable that the high thermal conductive material 12 is arranged closer to the core material 10.

As described above, according to the fire-resistant wood member 200, high heat conduction between the first burn-stop layer 14A and the second burn-stop layer 14B in the region including the corner portion 16 where the heat energy is concentrated and becomes a weak point in fire resistance. A material 12 is provided, and by dispersing the thermal energy concentrated in the corner portion 16 through the high heat conductive material 12 in the direction along the surface of the core material, the temperature rise of the corner portion 14 is suppressed, and the temperature rise thereof is suppressed. Fire resistance performance can be significantly improved. Therefore, even if the member is made thinner, the structural performance equal to or higher than that of the conventional one can be ensured, and the cross section of the member can be slimmed down and the cost can be reduced. Further, by using the refractory wood member 200 for pillars (or beams) in the room, the openness of the room space is enhanced, and the room can be effectively utilized.

(Verification of Action and Effect of the Present Invention)
Next, verification of the action and effect of the present invention will be described.
In this verification, as an example, a wooden pillar in which a 10 cm square core material is covered with a heat insulating material (burn-off layer) made of a gypsum board having a total thickness of 30 mm and a 20 cm square core material made of a gypsum board having a total thickness of 30 mm. Heat conduction was calculated when a wooden pillar with a regular square cross section covered with a heat insulating material (burn-off layer) was heated for 1 hour according to the standard heating temperature-time curve defined in IOS 834 from its four sides. In the calculation, a metal plate (steel plate equivalent to SS400) was inserted as a high thermal conductive material between the heat insulating material and the wood core material, and the thickness thereof was used as a calculation parameter. The water content of the gypsum board was 6 wt%, the water content of the core material was 10 wt%, and the latent heat of vaporization at 100 ° C. was taken into consideration. In this analysis, it was assumed that the wood-based material does not burn even if the ignition temperature of the wood-based material is exceeded. FIGS. 3 and 4 show the time course of the corner temperature, and FIGS. 5 and 6 show the temperature distribution of the core material surface at 30 minutes and 60 minutes after the start of heating.

From FIGS. 3 and 4, it can be seen that by inserting the steel plate (metal plate), the temperature rise at the corner portion is suppressed as compared with the case where the steel plate is not inserted. The thicker the steel sheet, the greater the effect of suppressing the temperature rise is due to the large heat capacity of the steel sheet. Further, regarding the calculation result of the thickness of each steel plate, there is no big difference in the corner temperature between the case where the core material cross section is 10 cm × 10 cm and the case where the core material cross section is 20 cm × 20 cm. From this, it can be said that the influence of the size of the cross section of the core material is small in the dispersion of the thermal energy concentrated in the corners.

In the surface temperature distribution of the core material 60 minutes after the start of heating in FIGS. 5 and 6, there is a range in which the temperature with the steel plate is higher than that without the steel plate. That is, in the case of a core material of 10 cm × 10 cm, the temperature is higher than that of “without steel plate” in the range of 25 mm or more away from the corner when the steel plate thickness is 0.1 mm and in the range of 30 mm or more when the steel plate thickness is 0.5 mm. In the case of a 20 cm × 20 cm core material, the temperature is higher than that of “without steel plate” in a range of about 30 to 60 mm away from the corner when the steel plate thickness is 0.1 mm. It can be said that this indicates that the thermal energy of the corners is moved in the direction parallel to the surface of the core material because the thermal conductivity of the steel plate is larger than that of the gypsum board or the wood core material.

From the results of FIGS. 3 and 4, it was considered that the influence of the size of the core material cross section was small in the dispersion of the thermal energy concentrated in the corner portion, and in FIG. 6, the distance from the corner portion was 60 mm or more. Since the surface temperature of the side surface of the core material when heated for 1 hour in a distant range is almost the same, if the steel plate thickness is 5 mm or less, the steel plate layer should be provided in the range of 60 mm or more from the corner. , It can be said that it has the effect of suppressing the temperature rise in the corners.

In the above description, a member having a quadrangular cross section has been taken as an example, but the present invention is not limited to this, and the present invention can be applied to a wooden member having a triangular cross section or a polygonal cross section of a pentagon or more, and has a quadrangular cross section. It is possible to achieve the same action and effect as in the case. That is, providing the high thermal conductive material 12 on the surface of the core material 10 including the corner portion 16 is effective in suppressing the temperature rise of the corner portion 16 and improving the fire resistance performance.

As described above, according to the fire-resistant wood member according to the present invention, it is a fire-resistant wood member having a core material made of a wood material that supports a load, and at least the surface of a corner portion in a cross section of the core material. Since a high thermal conductive material having a higher thermal conductivity than the core material is provided in a predetermined region including, the temperature rise of the corner portion, which is a weak point in fire resistance, is suppressed, and the fire resistance performance of the corner portion is remarkably improved. Can be done. Therefore, even if the member is made thinner, the structural performance equal to or higher than that of the conventional one can be ensured, and the cross section of the member can be slimmed down and the cost can be reduced. Further, by using this refractory wood member for pillars, beams, etc. in the room, the openness of the room space is enhanced, and the room can be effectively utilized.

Further, according to another fire-resistant wood member according to the present invention, a burn-stop layer or finishing material provided on the outside of the core material is further provided, and the high thermal conductive material is provided between the core material and the burn-stop layer or finishing material. Since it is provided and has a higher thermal conductivity than the burn-off layer or the finishing material, the high thermal conductive material can suppress the temperature rise of the corner portion, which is a weak point in terms of fire resistance, and can significantly improve the fire resistance performance of the corner portion. Further, the non-burning layer can suppress heat transfer to the core material due to a fire and prevent carbonization and combustion of the core material. Further, the finishing material can give a wood texture to the outside of the core material.

Further, according to another fire-resistant wood member according to the present invention, a second burn-stop layer provided on the outside of the core material and a first burn-stop layer provided on the outside of the second burn-stop layer are further provided to provide high heat. The conductive material is provided between the second burn-stop layer and the first burn-stop layer, and has a higher thermal conductivity than the second burn-stop layer and the first burn-stop layer. It is possible to suppress the temperature rise of the corner portion and significantly improve the fire resistance performance of the corner portion. Further, the second burn-off layer and the first burn-off layer can suppress heat transfer to the core material due to a fire and prevent carbonization and combustion of the core material.

Further, according to another fire-resistant wood member according to the present invention, a burn-stop layer provided on the outside of the core material and a finishing material provided on the outside of the burn-stop layer are further provided, and the high thermal conductive material is a core material. Since it is provided between the and the stop-burn layer or at least one of the stop-burn layer and the finishing material, it has a higher thermal conductivity than the core material and the stop-burn layer, or the stop-burn layer and the finishing material. The high thermal conductive material can suppress the temperature rise of the corners, which is a weak point in terms of fire resistance, and can significantly improve the fire resistance performance of the corners. Further, the non-burning layer suppresses the transfer of heat to the core material due to a fire, prevents carbonization and combustion of the core material, and the finishing material can impart a wood texture to the outside of the core material.

As described above, the refractory wood member according to the present invention is useful for use as a building structural member, and is particularly suitable for slimming the cross section of the member and thus reducing the cost.

10 Core material 12 High thermal conductive material 14 Stop-burning layer 14A First stop-burning layer 14B Second stop-burning layer 16 Corner corner (corner)
100,200 refractory wood members

Claims (2)

A fire-resistant wood-based member made of a wood-based material that supports a load and having a core material having a regular square cross section and a burn-off layer or finishing material provided on the outside of the core material.
Only the length 1/4 of the range of one side of the cross section of the core surface of the corner portion in the cross section of the core member from the angular portion of including the entire circumference of the region, a large high thermal conductivity of the thermal conductivity than the core material The material is provided,
The high thermal conductive material is provided between the core material and the stop-burning layer or the finishing material, and has a higher thermal conductivity than the stop-burning layer or the finishing material. A fire-resistant wood member characterized by suppressing a temperature rise of the corner portion, which is a weak point in terms of fire resistance, and improving the fire resistance performance of the corner portion by dispersing in a direction along the surface of the corner. A fire-resistant wood having a core material made of a wood-based material that supports a load, a second burn-stop layer provided on the outside of the core material, and a first burn-stop layer provided on the outside of the second burn-stop layer. It ’s a member,
A high thermal conductive material having a higher thermal conductivity than the core material is provided in a predetermined region including at least the surface of the corner portion in the cross section of the core material.
High thermal conductivity material is disposed between the second burning blind layer and the first burn blind layer, resistance to fire wood you wherein the thermal conductivity is greater than the second burning blind layer and the first burning blind layer Element.

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