JP7104673B2 - Building board - Google Patents

Description

The present invention relates to a building board and a method for manufacturing a building board. More specifically, the present invention relates to a building board and a method for manufacturing a building board, which is formed from a molding material containing a hydraulic inorganic material as a main component and has a core portion and a skin portion covering the core portion.

Conventionally, building boards mainly composed of materials such as cement and gypsum have been used for various building materials such as outer walls of buildings. In recent years, due to a shortage of craftsmen and an aging population, there is a demand for weight reduction of building boards.

For example, Patent Document 1 describes a building board in which a plurality of hollow portions penetrating in the longitudinal direction of the base material are provided in the lateral direction (width direction) of the base material. Such a building board is lighter in weight than a building board having no hollow portion, and is excellent in transportability, workability, and reduction of burden on the building frame.

Further, as a further lightweight method for building boards, it is considered to reduce the specific density of the materials forming the building boards.

Japanese Unexamined Patent Publication No. 2000-210921

However, the strength of building boards made of low-density materials tends to decrease, and when workers such as craftsmen transport or construct the building boards, the building boards are prone to breakage or other damage. There was a problem.

The present invention has been made in view of the above points, and provides a building board and a method for manufacturing a building board, which is lighter than the conventional one, has sufficient strength, and is less likely to be damaged such as swinging. The purpose is to do.

One aspect of the building board according to the present invention includes a plate-shaped core portion and a skin portion that covers at least the front surface and the back surface of the core portion and both side surfaces facing each other and is integrated with the core portion. The core portion is formed of a cured product of a core material, and the skin portion is formed of a cured product of a skin material containing an inorganic main material and reinforcing fibers. The skin portion bites into the core portion in the recess formed by pressing on the surface of the skin portion. The skin portion has a higher specific density than the core portion, and a part of the skin portion bites into a part of the core portion to form a rib.

The building board of the present invention has ribs formed of a skin material having a higher specific density than the core material even if the core portion is formed by using a core material having a lower specific density than the skin material. It can be reinforced with ribs to increase its strength, and although it is lighter than before, it is less likely to break or break.

FIG. 1A is a schematic cross-sectional view of a building board according to the first embodiment of the present invention. FIG. 1B is an enlarged view of a main part of the building board shown in FIG. 1A. FIG. 2A is a schematic cross-sectional view of the building board according to the first reference form. FIG. 2B is a schematic cross-sectional view of the building board according to the second reference form. FIG. 2C is a schematic cross-sectional view of the building board according to the third reference form. FIG. 2D is a schematic cross-sectional view of the building board according to the fourth reference embodiment. FIG. 3 is a schematic plan view of an extrusion molding machine used for manufacturing a building board according to the first embodiment of the present invention, and a mold included in the extrusion molding machine. FIG. 4 is a schematic cross-sectional view of the mold shown in FIG. FIG. 5 is a schematic perspective view of a core provided inside the mold shown in FIG. FIG. 6A is a schematic plan view of a hollow pin provided inside the mold shown in FIG. FIG. 6B is a schematic side view of the hollow pin shown in FIG. 6A. FIG. 7 is a schematic perspective view showing a state in which the hollow pin shown in FIG. 6A is provided inside the core shown in FIG. FIG. 8 is a schematic cross-sectional view showing how the skin material flows when the building board according to the first embodiment of the present invention is manufactured. FIG. 9 is a schematic perspective view of a core used for manufacturing the building board according to the first reference embodiment. FIG. 10 is a schematic perspective view of a core used for manufacturing the building board according to the second reference embodiment. FIG. 11 is a schematic perspective view of a core used for manufacturing the building board according to the third reference embodiment. FIG. 12 is a schematic perspective view of a core used for manufacturing the building board according to the fourth reference embodiment.

Hereinafter, modes for carrying out the present invention will be described.

(First Embodiment)
FIG. 1A shows the building board 1 of the present embodiment. This figure shows a cross-sectional view when the building board 1 is cut along a line parallel to the lateral direction. Therefore, the building board 1 is formed to be long in the direction orthogonal to the lateral direction (the direction perpendicular to the paper surface of FIG. 1A). The building board 1 is formed in a substantially rectangular shape in a plan view, and real parts that can be connected to other building boards 1 are provided at both side ends (both ends in the lateral direction).

The building board 1 is formed to include a core portion 2 and a skin portion 3. The core portion 2 is formed in a plate shape, and the skin portion 3 is formed so as to cover the front surface and the back surface of the core portion 2 and both end faces (end faces in the lateral direction). Further, the core portion 2 and the skin portion 3 are integrally formed, and a plurality of ribs 30 that bite into the core portion 2 are integrally formed on the skin portion 3. The rib 30 is formed so as to extend along the longitudinal direction of the core portion 2 (the same as the longitudinal direction of the building board 1). Further, a plurality of hollow portions 4 are formed in the core portion 2 . The hollow portion 4 is a hollow portion formed over substantially the entire length of the core portion 2 in the longitudinal direction.

Each rib 30 and each hollow portion 4 are formed so as to extend along one edge in the longitudinal direction of the core portion 2, and the plurality of ribs 30 and the plurality of hollow portions 4 are the above-mentioned one of the core portion 2. They are arranged in parallel in the direction orthogonal to the edge (the lateral direction of the building board 1). Considering the appearance and the like, the thickness of the skin portion 3 is preferably 1 mm or more, and preferably 1/3 or less of the thickness of the entire building board 1.

A pattern is formed on the surface of the building board 1 (the surface of the skin portion 3) by the recesses 31. Further, the surface of the building board 1 may be coated with a sealer and a paint for surface finishing, if necessary.

The building board 1 can swing 5 times or more under the conditions of an amplitude of 200 mm and a cycle of 1 time / second in a state where one end in the direction (longitudinal direction) along the rib 30 is fixed. The term "amplitude possible" as used herein means that even if the building board 1 is oscillated under this condition, the building board 1 is not damaged such as runout. By providing the building board 1 with such a configuration, it is possible to suppress the swinging of the building board 1 when the building board 1 is constructed or transported.

The number of ribs 30 and the distance between the ribs 30 are affected by the shape of the ribs 30, the size of the ribs 30, and the like, but are preferably 1/100 mm or more. In this case, damage to the building board 1 during transportation can be particularly suppressed. The heights X of the plurality of ribs 30 may be different from each other, or may all be the same. The cross-sectional shapes of the plurality of ribs 30 may be different or all may be the same. In order to sufficiently suppress damage to the building board 1, the height X of the rib 30 shown in FIG. 1B is preferably 3 mm or more. If the height X of the rib 30 is less than 3 mm, damage to the building board 1 may not be sufficiently suppressed. The cross-sectional shape of the rib 30 provided on the back surface side of the core portion 2 is triangular, but is not limited thereto. For example, the cross-sectional shape of the rib 30 may be a square shape or a semicircular shape.

Since the building board 1 as described above has ribs 30, it is not easily damaged. That is, when a worker such as a craftsman transports the building board 1 by himself, the building board 1 may be held aside at a substantially central portion in the longitudinal direction. In this case, as the worker moves, the building board 1 is swung around, and a load such as bending in the thickness direction is likely to be applied to both ends of the building board 1 in the longitudinal direction. Therefore, in the building board 1 of the present embodiment, long ribs 30 are provided in a direction parallel to the longitudinal direction of the building board 1, whereby even if the building board 1 is subjected to the above load, the building board 1 is provided. 1 can be reinforced with ribs 30, and damage such as swinging during transportation of the building board 1 can be suppressed.

On the other hand, when there are two workers, each worker holds both ends of the building board 1 in the longitudinal direction and carries the building board 1. Further, the building board 1 may be placed against a wall or the like with its longitudinal direction turned up and down. In these cases, the substantially central portion of the building board 1 in the longitudinal direction is warped and deformed so as to bend, and a load is applied to the substantially central portion of the building board 1. However, since the building board 1 is provided with the rib 30 as described above, Even when a load is applied to the substantially central portion of the building board 1, damage can be suppressed.

Further, it is preferable that the rib 30 is provided on the back surface side of the core portion 2. As described above, when two workers carry the building board 1 or lean against a wall, the surface side of the building board 1 is often turned up. Therefore, a load in the direction of being pulled in the longitudinal direction is likely to be applied to the building board 1 on the back surface side. Therefore, by providing the rib 30 on the back surface side of the core portion 2, the back surface of the building board 1 is reinforced by the rib 30, and when the building board 1 is transported by two people or leans against a wall. Damage can be particularly suppressed. Of course, the rib 30 may be provided on the surface side of the core portion 2, and in this case, the strength of the building board 1 can be further improved and damage is unlikely to occur.

Hereinafter, the manufacturing method of the above-mentioned building board 1 will be described.

The core portion 2 is formed of a cured product of the core material, and the skin portion 3 is formed of a cured product of the skin material. Both the core material and the skin material are molding materials containing a hydraulic inorganic material, but the core material is prepared to have a lower specific density than the skin material. The core material and the skin material contain, for example, an inorganic main material, an inorganic admixture, an organic admixture, reinforcing fibers, and water.

As the inorganic main material, a compound containing at least one of silicon and calcium can be used, and a hydraulic inorganic material such as cement can be used. The inorganic main material may further contain fly ash, silica fume, silica stone powder and the like.

The inorganic admixture is an inorganic foam used as a lightweight aggregate, and examples thereof include pearlite, fly ash balloon, and vermiculite. Further, as the inorganic admixture, mica, wallastnite and the like can be used.

Examples of the organic admixture include methyl cellulose and organic foamed particles. Examples of the organic foamed particles include foamed particles such as a styrene resin, a vinylidene chloride resin, and an acrylonitrile resin.

Examples of the reinforcing fibers include natural fibers such as pulp fibers, organic fibers such as polypropylene and vinylon, and inorganic fibers such as glass fibers, rock wool and carbon fibers.

The blending ratio of each component contained in the core material and the skin material is not particularly limited, but the blending ratio of each component is appropriately adjusted so that the specific gravity of the core material is lower than the specific density of the skin material. By making the specific gravity of the core material lower than the specific gravity of the skin material, the absolute dry specific density of the core portion 2 can be made lower than the absolute dry specific density of the skin portion 3, and the weight of the building board 1 can be reduced. .. Further, the skin portion 3 having a high specific density is made denser than the core portion 2, the strength of the skin portion 3 can be made higher than that of the core portion 2, and the strength of the entire building board 1 can be improved.

The mixing ratio of each component contained in the core material is, for example, that the core material contains an inorganic main material in the range of 73 to 97% by weight, the inorganic admixture in the range of 1 to 20% by weight, and the organic admixture in the range of 1 to 20% by weight. It is preferable that the reinforcing fiber is contained in the range of 1 to 3.5% by weight and the reinforcing fiber is contained in the range of 1 to 3.5% by weight. The mixing ratio of each component contained in the skin material is, for example, an inorganic main material in the range of 69.5 to 97.5% by weight, an inorganic admixture in the range of 1 to 20% by weight, and an organic substance. It is preferable that the system admixture is contained in the range of 1 to 3.5% by weight and the reinforcing fiber is contained in the range of 1 to 7% by weight.

The building board 1 is manufactured by extrusion-molding a core material and a skin material with an extrusion molding machine 10 as shown in FIG.

The extrusion molding machine 10 includes a first extruder 11 and a second extruder 12. The first extruder 11 and the second extruder 12 are connected to the mold 100. The mold 100 is provided with an inflow port 103 at its tip and an extrusion port 104 at its rear end. The inflow port 103 is connected to the first extruder 11. Therefore, the skin material flows into the inflow port 103 from the first extruder 11.

FIG. 4 shows a schematic cross-sectional view of the mold 100. The mold 100 includes an upper mold 101, a lower mold 102, a core 105, a flow path 106, a flow path 107, and a flow path 108. The upper die 101 and the lower die 102 are stacked so as to face each other in the vertical direction. The flow path 106, the flow path 107, and the flow path 108 merge with the flow path 106 and the flow path 107 in the mold 100 at a merging portion 109 provided on the extrusion port 104 side. Therefore, the extrusion port 104 is connected to the flow path 106, the flow path 107, and the flow path 108.

A cavity is formed inside the mold 100. A core 105 is provided in this cavity. The flow path 106 is between the lower surface of the upper mold 101 and the upper surface of the core 105 appearing in the cross-sectional view of FIG. 4, and the flow path 107 is between the upper surface of the lower mold 102 and the lower surface of the core 105. Is. The flow path 106 and the flow path 107 are connected to the inflow port 103. Therefore, the skin material flows through the flow path 106 and the flow path 107. The thickness of the core 105 gradually decreases from the vicinity of the inflow port 103 toward the inflow port 103. Further, the thickness of the end of the core 105 on the extrusion port 104 side gradually decreases toward the extrusion port 104. The tip of the core 105 on the extrusion port 104 side is arranged so as to face the extrusion port 104. The upper surface of the tip of the core 105 is formed as a flat inclined surface 111 toward the tip, and the lower surface of the tip of the core 105 is formed as a flat inclined surface 112 toward the tip. A flow path 108 is formed inside the core 105. This flow path 108 is connected to the second extruder 12. Specifically, the flow path 108 in the core 105 is connected to the second extruder 12 via a pipe 17. Therefore, the core material kneaded by the second extruder 12 flows into the flow path 108. Further, a rectangular opening 110 leading to the flow path 108 is formed at the tip of the core 105.

FIG. 5 shows a schematic perspective view of the core 105. The tip of the core 105 is formed of a pair of tip members 121 provided at the top and bottom. The tip member 121 is formed as an inclined surface 122 whose upper surface is inclined downward toward the downstream side. Inclined portions 123 are provided at both end portions of the tip member 121. Each inclined portion 123 is formed in a substantially triangular shape in a plan view so as to be inclined downward from the side end portion of the inclined surface 122 toward the side, and is formed on two sides located on the outer side of each inclined portion 123. Is provided with a side wall portion 124.

The tip of the core 105 is formed by vertically symmetrically providing the tip member 121 as described above. In this case, the upper tip member 121 and the lower tip member 121 are provided upside down. The upper tip member 121 and the lower tip member 121 are joined to each other with the side wall portions 124 facing up and down, and an opening 110 leading to the flow path 108 is formed between the tip edges of the facing inclined surfaces 122. The opening 110 is formed by being surrounded by the tip edge of the inclined surface 122, the inclined portion 123, and the side wall portion 124. Further, the inclined surface 122 of the upper tip member 121 is formed as the inclined surface 111 of the core 105, and the inclined surface 122 of the lower tip member 121 is formed as the inclined surface 112 of the core 105. Further, the inclined portion 123 of the upper tip member 121 is formed so as to be inclined downward from the side end portion of the inclined surface 122 toward the side. Further, the inclined portion 123 of the lower tip member 121 is formed so as to be inclined upward from the side end portion of the inclined surface 122 toward the side.

A hollow molded body 300 is provided in the flow path 108 of the core 105. As shown in FIG. 6A, the hollow molded body 300 includes a main body portion 301 and a plurality of protruding rods 302. As shown in FIG. 6B, the plurality of protruding rods 302 are arranged in a row at intervals. The dimensions and shape of the plurality of protruding rods 302 are not particularly limited.

FIG. 7 shows a core 105 in which the hollow molded body 300 is arranged in the flow path 108. When the hollow molded body 300 is arranged in the flow path 108, a part of the plurality of protruding rods 302 protrudes from the opening 110. By providing the core 105 in the mold 100 and extrusion molding using the mold 100, it is possible to manufacture a building plate 1 having a hollow structure in which the hollow portion 4 is formed in the core portion 2.

Then, the building board 1 is manufactured as follows using the extrusion molding machine 10.

First, the skin material is charged into the inlet 13 of the first extruder 11, and the core material C is charged into the inlet 15 of the second extruder 12. The skin material S and the core material C are conveyed while being kneaded by a screw 14 provided in the first extruder 11 and a screw 16 provided in the second extruder 12, respectively.

Next, the core material C flows from the second extruder 12 into the flow path 108 via the pipe 17. Further, the skin material flows from the first extruder 11 through the inflow port 103 into the flow path 106 and the flow path 107.

Next, the core material C that has passed through the flow path 108 reaches the opening 110. At this time, the core material C flows while avoiding the protruding rod 302 of the hollow molded body 300 provided in the flow path 108. The core material C discharged from the opening 110 is formed into a plate shape having a hollow structure in accordance with the shape of the opening 110 and the shape of the protruding rod 302.

Further, the skin material S passing through the flow path 106 and the skin material S passing through the flow path 107 merge at the merging portion 109. As a result, the core material C formed into a plate shape is wrapped with the skin material S. FIG. 8 shows how the skin material S flows at the confluence portion 109. This figure is a cross-sectional view of the confluence portion 109 of the mold 100. As shown by the arrows in this figure, the skin material S flows to both sides of the protruding rod 302 so as to avoid the protruding rod 302 protruding from the opening 110. Therefore, a large amount of skin material S flows between the adjacent protruding rods 302. In particular, a large amount of skin material S flows below the protruding rod 302. As a result, when the core material C is wrapped by the skin material S, a part of the skin material S bites into the core material C, and ribs 30 are formed on both sides of the hollow portion 4 on the back surface side of the core portion 2 of the building board 1. The corresponding part is formed.

Next, the core material C and the skin material S are extruded from the extrusion port 104 while the core material C is wrapped by the skin material S. By cutting the core material C and the skin material S to arbitrary lengths, an uncured molded product (green sheet) is formed.

Next, by applying a press or the like to the surface side of the uncured molded body, a recess corresponding to the recess 31 provided on the surface of the skin portion 3 of the building board 1 shown in FIG. 1B is formed. The concave portion 31 can make a pattern on the surface of the building board 1. Further, when this recess is formed, a part of the skin material bites into the core material, and a rib corresponding to the rib 30 provided on the surface side of the core portion 2 can be formed. That is, by forming recesses on the surface of the uncured molded product by pressing or the like, the surface pattern of the building board 1 can be formed, and ribs can be formed on the surface side of the core portion 2.

By curing and curing this uncured molded body, the building board 1 as described above is manufactured.

( First reference form)
The building board 1 of the first reference form shown in FIG. 2A is formed so that the shape, spacing, and number of ribs 30 are different from those of the building board 1 of FIGS. 1A and 1B. When manufacturing the building board 1, it is preferable to use the core 205 shown in FIG. 9 instead of the core 105 described above.

As shown in FIG. 9, the tip portion of the core 205 has the same configuration as the core 105 shown in FIG. 7, except that it is formed of two tip members 221. A plurality of rib forming recesses 223 are provided on the inclined surface 222 of the tip member 221. The rib forming recess 223 is formed recessed from the inclined surface 222. The plurality of rib forming recesses 223 are each formed in a strip shape in a plan view. The rib forming recesses 223 are arranged in a direction orthogonal to the inclination direction of the inclined surface 222, respectively. The cross-sectional shape of the rib forming recess 223 is, for example, rectangular, but is not limited to this, and may be, for example, triangular or semicircular. The opening 110 of the core 205 has an upper side formed by the tip edge of the inclined surface 222 and a lower side formed by the tip edge of the inclined surface 222. The hollow molded body 300 shown in FIGS. 6A and 6B is provided in the flow path 108 of the core 205. Therefore, a plurality of protruding rods 302 project from the opening 110.

When the building board 1 is manufactured by using the mold 100 to which the core 205 is applied, the skin material passing through the flow path 106 and the skin material passing through the flow path 107 merge at the merging portion 109. A portion corresponding to the rib along the rib forming recess 223 is formed on the lower surface of the skin material passing through the flow path 106 and the upper surface of the skin material passing through the flow path 107. Further, the core material that has passed through the flow path 108 is formed into a plate shape having a hollow structure by a plurality of projecting rods 302. In this state, the core material is wrapped with the skin material. Therefore, the portion corresponding to the rib of the skin material bites into the core material, and the portion corresponding to the rib 30 is formed on the back surface side and the front surface side of the core portion 2. By curing and curing this uncured molded body, the building board 1 shown in FIG. 2A is manufactured.

( Second reference form)
The building board 1 of the second reference form shown in FIG. 2B has a structure in which the hollow portion 4 is not formed in the core portion 2, that is, a solid structure. The skin portion 3 of the building board 1 is provided with a plurality of ribs 30 on the back surface side and the front surface side of the core portion 2. When manufacturing the building board 1, it is preferable to use the core 305 shown in FIG. The core 305 has the same configuration as the core 205 shown in FIG. 9, except that the hollow molded body 300 is not provided in the flow path 108.

When the building board 1 is manufactured by using the mold 100 to which the core 305 is applied, the skin material passing through the flow path 106 and the skin material passing through the flow path 107 merge at the merging portion 109. A portion corresponding to the rib along the rib forming recess 223 is formed on the lower surface of the skin material passing through the flow path 106 and the upper surface of the skin material passing through the flow path 107. Further, the core material that has passed through the flow path 108 is formed in the shape of a plate having a solid structure. In this state, the core material is wrapped with the skin material. Therefore, the skin material bites into the core material, and portions corresponding to the ribs 30 are formed on the back surface side and the front surface side of the core portion 2. By curing and curing this uncured molded body, the building board 1 shown in FIG. 2B is manufactured.

( Third reference form)
In the building board 1 of the third reference form, as shown in FIG. 2C, the skin portion 3 has ribs 30 only on the surface side of the core portion 2. When manufacturing the building board 1, it is preferable to use the core 405 shown in FIG. Of the two upper and lower tip members 221 of the core 405, the rib forming recess 223 is formed only on the upper tip member 221 and the rib forming recess 223 is not formed on the lower tip member 221. Has the same configuration as the core 305 shown in FIG.

When the building board 1 is manufactured by using the mold 100 to which the core 405 is applied, the skin material passing through the flow path 106 and the skin material passing through the flow path 107 merge at the merging portion 109. A portion corresponding to the rib along the rib forming recess 223 is formed on the lower surface of the skin material passing through the flow path 106, and a portion corresponding to the rib is formed on the upper surface of the skin material passing through the flow path 107. Not formed. Further, the core material that has passed through the flow path 108 is formed in the shape of a plate having a solid structure. In this state, the core material is wrapped with the skin material. Therefore, the portion corresponding to the rib of the upper skin material bites into the core material, and the portion corresponding to the rib 30 provided on the surface side of the core portion 2 is formed. By curing and curing this uncured molded body, the building board 1 shown in FIG. 2C is manufactured.

( Fourth reference form)
As shown in FIG. 2D, the building board 1 of the fourth reference form has the skin portion 3 provided with the rib 30 only on the back surface side of the core portion 2. When manufacturing the building board 1, the core 405 shown in FIG. 12 can be used. Of the two upper and lower tip members 221 of the core 405, the rib forming recess 223 is formed only on the lower tip member 221 and the rib forming recess 223 is not formed on the upper tip member 221. Has the same configuration as the core 305 shown in FIG. Then, when the building board 1 is manufactured by using the mold 100 to which the core 405 is applied, the skin material passing through the flow path 106 and the skin material passing through the flow path 107 merge at the merging portion 109. However, a portion corresponding to the rib along the rib forming recess 223 is formed on the upper surface of the skin material that has passed through the flow path 107, but is not formed on the lower surface of the skin material that has passed through the flow path 106. Further, the core material that has passed through the flow path 108 is formed in the shape of a plate having a solid structure. In this state, the core material is wrapped with the skin material. Therefore, the portion corresponding to the rib of the lower skin material bites into the core material, and the portion corresponding to the rib 30 provided on the surface side of the core portion 2 is formed. By curing and curing this uncured molded body, the building board 1 shown in FIG. 2D is manufactured.

Hereinafter, the present invention will be specifically described with reference to Examples.

(Examples 1 and 2, Comparative Example 2)
A core material and a skin material were prepared by blending an inorganic main material, an inorganic admixture, an organic admixture, reinforcing fibers, and water in the proportions shown in Table 1 below. The water content in Table 1 is the ratio of water to the total solid content in each of the core material and the skin material.

The above core material and skin material were molded using an extrusion molding machine 10 including a first extruder 11, a second extruder 12, and a mold 100 shown in FIG. 3, to prepare a molded product. The mold 100 includes a core 505 shown in FIG. The core 505 is provided with rib forming recesses 223 on the inclined surface 222 of the lower tip member 221. The number of rib forming recesses, that is, the number of ribs 30, is as shown in Table 2 below. Changed to. The distance between the rib forming recesses was 100 mm.

This molded product was steam-cured at 60 to 80 ° C. for 24 hours, and then autoclaved at a maximum temperature of 160 ° C. for a total of 10 hours. Then, the water content of the molded product was adjusted to 10% by a dryer.

As a result, a building board 1 having dimensions of width 500 mm, thickness 16 mm, and length 3000 mm, and having a core portion 2 and a skin portion 3 as shown in FIGS. 1A and 1B was manufactured. The thickness of the skin portion 3 of the building board 1 was 1 mm. Further, the heights X of the plurality of ribs 30 included in the skin portion 3 were within the range of 3 to 5 mm.

The absolute dry specific density of the core portion 2 of the building board 1 was 0.70 , and the absolute dry specific gravity of the skin portion 3 was 1.02 . The bending strength of the building board 1 was 8.0 MPa.

(Comparative Example 1)
Building boards were manufactured in the same manner as in Examples 1 and 2 and Comparative Example 2 except that the rib forming recess 223 was not provided on the inclined surface 222 on the lower side of the core 505 included in the mold 100.

The dimensions, absolute dry specific gravity, and bending strength of this building board were the same as those in Examples 1 and 2.

(Evaluation of handleability)
One end of the building board 1 of Examples 1 and 2 and Comparative Examples 1 and 2 was held and fixed, and the unfixed end of the building board 1 was oscillated at an amplitude of about 200 mm and a cycle of 1 time / sec. .. The number of amplitudes until the building board 1 breaks is shown in Table 2 below together with the number of ribs 30.

As shown in Table 2, in the building boards of Examples 1 and 2 in which the skin portion 3 is provided with the rib 30 provided on the back surface side of the core portion 2, the skin portion 3 is not provided with the rib 30 in Comparative Example 1. The number of amplitudes until it breaks is larger than that of the building board of Comparative Example 2 in which the number of building boards and ribs 30 is small. Therefore, the building boards of Examples 1 and 2 are less likely to be damaged during transportation than the building boards of Comparative Examples 1 and 2.

1 Building board 2 Core part 3 Skin part 30 Ribs 31 Recesses

Claims (3)

Plate-shaped core and
A skin portion that covers at least the front surface and the back surface of the core portion and both side surfaces facing each other and is integrated with the core portion.
With
The core portion is formed of a cured product of the core material, and the core portion is formed.
The skin portion is formed of a cured product of a skin material containing an inorganic main material and reinforcing fibers.
In the recess formed by pressing on the surface of the skin portion, the skin portion bites into the core portion.
The skin portion has a higher specific density than the core portion,
A building board in which ribs are formed by a part of the skin portion biting into a part of the core portion. The recess forms a surface pattern,
The building board according to claim 1. The thickness of the skin portion is 1 mm or more .
The core material contains an inorganic main material and reinforcing fibers.
The building board according to claim 1 or 2.

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