Tread and stair

Abstract

To provide treads for stairs capable of balancing fire resistance and design.SOLUTION: A tread used for stairs is composed of carbon fiber reinforced plastic, and the tensile modulus of carbon fiber constituting the carbon fiber reinforced plastic is 600 GPa or higher, and the tensile strength of the carbon fiber is 2500 MPa or higher.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to treads and stairs. [Background technology]

[0002] Conventionally, stairs with improved fire resistance have been known to ensure an escape route in the event of a fire (see, for example, Patent Document 1). The treads of such stairs are made of reinforced concrete or steel. In order to further improve fire resistance, it was necessary to take measures such as attaching fireproof boards or constructing the stairs from thick wood. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-41311 A Summary of the Invention [Problem to be solved by the invention]

[0004] Conventional staircase treads with improved fire resistance have the problem that they are not suitable for stairs in private homes, etc., where high design quality is required, such as an open exterior. In addition, there are problems in that heavy work is required on-site during construction, and the beams and walls that support the treads need to be strong.

[0005] The present disclosure has been made in consideration of the above, and aims to provide a staircase tread that is both fire-resistant and aesthetically pleasing. [Means for solving the problem]

[0006] The present disclosure relates to a tread for use in a staircase, the tread being made of carbon fiber reinforced plastic, the carbon fibers constituting the carbon fiber reinforced plastic having a tensile modulus of elasticity of 600 GPa or more and a tensile strength of the carbon fibers being 2500 MPa or more. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a perspective view showing a staircase provided with treads according to a first embodiment. [Diagram 2] FIG. 1 is a side view showing a staircase provided with treads according to a first embodiment. [Diagram 3] FIG. 2 is a bottom view showing a staircase provided with treads according to the first embodiment. [Figure 4] FIG. 11 is a perspective view showing a staircase provided with treads according to a second embodiment. [Diagram 5] FIG. 11 is a perspective view showing a staircase provided with treads according to a third embodiment. [Figure 6] FIG. 11 is a perspective view showing a staircase provided with treads according to a fourth embodiment. [Figure 7] FIG. 13 is a diagram showing the results of a combustion test according to the examples. [Figure 8] FIG. 13 is a diagram showing the results of a combustion test according to a comparative example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] First Embodiment A staircase 100 including a step 10 according to the present embodiment is shown in Figs. 1 to 3. In the following description, the staircase 100 will be described as including a support 20 that supports one end of the step 10 by fixing it to the main body 30. Specifically, the staircase will be described as a cantilever staircase in which the other end of the step 10 is not fixed to the main body 30 as shown in Figs. 1 to 3. On the other hand, the step according to the present disclosure can also be applied to a double-supported staircase in which both ends are supported, and does not need to include a support 20. In each drawing, the longitudinal direction (width direction) of the step 10 is shown as the X direction, the lateral direction (front-rear direction) of the step 10 is shown as the Y direction, and the vertical direction (thickness direction) is shown as the Z direction.

[0009] (Stepping board) As shown in Figs. 2 and 3, the step 10 is a plate-like member having a length L1X in the X direction, a length L1Y in the Y direction, and a length (thickness) L1Z in the Z direction. In Figs. 2 and 3, the step 10 is shown as a rectangular step, but the shape of the step 10 is not limited to a rectangular shape. When the shape of the step 10 is not rectangular, the length L1X in the X direction, the length L1Y in the Y direction, and the length (thickness) L1Z in the Z direction in this specification each refer to the maximum length. From the viewpoint of ensuring safety as a residential staircase, the length L1X is preferably 750 mm or more. For the same reason, the length L1Y is preferably 150 mm or more.

[0010] The step 10 has a uniform thickness, and the thickness L1Z is preferably 4 mm or more. This allows the step 10 to have a preferable fire resistance when the length L1X is 750 mm or more and the length L1Y is 150 mm or more. The thickness L1Z is preferably 30 mm or less. This allows the staircase 100 to have a preferable design. Therefore, the thickness L1Z is more preferably 4 mm or more and 30 mm or less.

[0011] The step 10 may be disposed in contact with the body 30, or may be fixed to the body 30. On the other hand, the step 10 and the body 30 do not have to be directly fixed to each other. In the following description, the body 30 to which the step 10 is fixed is described as a pillar. On the other hand, the object to which the step 10 is fixed is not limited to a pillar, and may be any object having a predetermined strength or more that can support at least the weight of a user of the cantilever staircase. The object may be, for example, a beam or girder.

[0012] The step 10 is made of carbon fiber reinforced plastic (hereinafter, "CFRP"). The carbon fibers constituting the CFRP have a tensile modulus of elasticity of 600 GPa or more and a tensile strength of 2500 MPa or more. An example of such carbon fiber is pitch-based carbon fiber. CFRP containing the above carbon fibers has both high thermal conductivity and high heat dissipation. Therefore, by making the step 10 from the above CFRP, the fire resistance of the staircase 100 can be improved. Furthermore, by making the step 10 from the above CFRP, the amount of deflection of the step 10 can be reduced even if the thickness L1Z of the step 10 is set to 30 mm or less.

[0013] The fiber volume content of the carbon fibers contained in the CFRP is preferably 50% or more and 80% or less, which allows the footboard 10 to have a preferable fire resistance.

[0014] The footboard 10 is obtained, for example, by overlapping and bonding CFRP prepreg sheets. The CFRP prepreg sheet is a sheet in which carbon fibers are uniformly impregnated with a matrix resin such as a thermosetting resin or a thermoplastic resin. Examples of the matrix resin include epoxy resins such as bisphenol A type epoxy resin, bisphenol F type epoxy resin, and multifunctional epoxy resin, unsaturated polyester resin, vinyl ester resin, polyamide resin, and acrylic resin. It is preferable that the matrix resin has an improved heat resistance.

[0015] The step board 10 preferably contains a heat-resistant resin. Specifically, it is preferable that the step board 10 contains at least one of cyanate ester, phenol, and polyimide resin. The heat-resistant resin may be contained as a matrix resin, or the heat-resistant resin may be contained together with the matrix resin.

[0016] It is preferable that the footboard 10 contains a flame retardant instead of the above-mentioned heat-resistant resin or in addition to the heat-resistant resin. The flame retardant is not particularly limited, and any known flame retardant such as a phosphorus-based flame retardant can be used.

[0017] The CFRP prepreg sheet is preferably one in which the carbon fibers are aligned in a predetermined direction. The step plate 10 is preferably configured so that the predetermined direction in which the fibers are oriented is along the X direction, which is the longitudinal direction of the step plate 10. This provides the step plate 10 with favorable fire resistance. The predetermined direction and the X direction of the step plate 10 are preferably approximately parallel, but may have a certain angle. Specifically, the angle between the predetermined direction and the X direction of the step plate 10 is preferably 0° or more and less than 45°.

[0018] (Support) 1 to 3, the support 20 includes lower supports 21 and 23a. The lower supports 21 and 23a are disposed in contact with the lower surface of the step board 10, and support the step board 10 from below.

[0019] The lower supports 21 and 23a and the fixing member 24 are fixed and integrated by a method such as welding. The lower supports 21 and 23a and the fixing member 24 may be bonded to the footboard 10 by a known adhesive.

[0020] (lower support) As shown in Figs. 2 and 3, the lower support 21 is a plate-like member having a length L2X in the X direction, a length L2Y in the Y direction, and a length (thickness) L2Za in the Z direction. The lower support 21 extends from one end (the column 30 side) of the footboard 10 to the other end. The material constituting the lower support 21 is not particularly limited, but is preferably a metal material. Examples of metal materials include steel. The shape of the lower support 21 is not limited to a rectangular shape as shown in Figs. 2 and 3. When the shape of the lower support 21 is not rectangular, the length L2X in the X direction, the length L2Y in the Y direction, and the length (thickness) L2Za in the Z direction each refer to the maximum length.

[0021] The lower support 21 may be provided with a rib 22. The rib 22 is a member that is joined to the lower surface of the lower support 21 by welding or the like and is disposed so as to protrude below the footboard 10. The maximum length of the rib 22 in the Z direction is L2Zb. By providing the lower support 21 with the rib 22, the amount of deflection of the footboard 10 can be further reduced.

[0022] As shown in Fig. 3, the rib 22 is preferably disposed in the center of the lower support 21 in the Y direction. The rib 22 is preferably inclined so that the length in the thickness direction Z tapers from the pillar 30 side toward the tip side of the footboard 10. With the above configuration, the rib 22 can be disposed so as to be difficult to see, improving the design.

[0023] 2 and 3, the lower support 23a is disposed in contact with the underside of one end of the footboard 10, which is on the pillar 30 side. The material constituting the lower support 23a is not particularly limited, but examples thereof include the same metal material as the lower support 21.

[0024] The shape of the lower support 23a is not particularly limited as long as it has a surface that contacts the lower surface of the footboard 10 and a surface that contacts the fixing member 24 perpendicular to the surface. Examples of the shape of the lower support 23a include a substantially rectangular parallelepiped shape, a substantially cubic shape, and a substantially triangular prism shape. From the viewpoint of resistance to deformation due to load, the lower support 23a preferably has a rectangular shape when viewed from the Y direction. On the other hand, the lower support 23a may be embedded inside the wall from the viewpoint of design. In this case, from the viewpoint of ease of embedding inside the wall, the shape of the lower support 23a is preferably an L-shape when viewed from the Y direction.

[0025] The lower support 23a may be a single member as shown in FIGS. 2 and 3, or a plurality of members may be provided along the Y direction of the footboard 10.

[0026] The lower supports 21 and 23a are required to have a certain level of strength to suppress bending of the tread 10. On the other hand, by configuring the lower supports 21 and 23a to be difficult to see, the design of the staircase 100 can be improved. For example, it is preferable that the area S2 of the lower surface of the lower support 21 is 0.71 times or less the area S1. The area S1 can be calculated from the lengths L1X and L1Y, and the area S2 can be calculated from the lengths L2X and L2Y.

[0027] (Fixing member) The fixing member 24 is disposed so as to abut against the upper and lower surfaces of the end portion of the footboard 10 on the pillar 30 side, which is one end side of the footboard 10 , and against the pillar 30 .

[0028] The fixing member 24 is formed with a hole h that communicates in the X direction when the fixing member 24 is disposed in contact with the pillar 30. In this case, a hole is also formed in the pillar 30 at a position corresponding to the hole h. The fixing member 24 is fixed to the pillar 30 by inserting a fixing tool such as a bolt into the hole h and fastening the fixing member 24 to the pillar 30 with a fastener such as a nut. The method of fixing the fixing member 24 to the pillar 30 is not limited to the above, and may be a method such as welding, or the above methods may be used in combination.

[0029] Second Embodiment Other embodiments of the present disclosure will be described below. Configurations similar to those in the first embodiment will be denoted by the same reference numerals and descriptions thereof may be omitted.

[0030] As shown in Fig. 4, the staircase 110 according to the second embodiment is a staircase in which both ends of the tread 10a are supported. The staircase 110 is an open-type staircase without risers. In the staircase 110, the tread 10a is fixed to a pair of left and right beams 31, 32. The beams 31, 32 are installed from the floor surface to the framework of the upper floor.

[0031] The step 10a is supported by the lower support 20a and fixed to the beams 31 and 32 by a pair of receiving members 31a and 32a. The receiving members 31a and 32a protrude above the beams 31 and 32. Therefore, the step 10a is attached so as to be raised above the beams 31 and 32. The step 10a is formed to be wider than the distance between the beams 31 and 32, and both ends protrude to the outside of the beams 31 and 32. Since both sides of the step 10a are fixed by the receiving members 31a and 32a, the thickness of the step 10a can be made smaller. The configuration of the step 10a other than the above can be the same as that of the first embodiment.

[0032] Third Embodiment As shown in Fig. 5, the staircase 120 according to the third embodiment is a staircase in which the center of the tread 10b is supported. The staircase 120 is an open-type staircase that does not have a riser. In the staircase 120, the tread 10b is fixed to a girder 33. The girder 33 is installed from the floor surface to the framework of the upper floor.

[0033] The step 10b is supported by the lower support 20b and fixed to the girder 33 by the receiving member 33a. The receiving member 33a protrudes upward beyond the girder 33. Therefore, the step 10b is attached so as to float above the girder 33. The step 10b is formed to be wider than the girder 33, with both ends protruding outward from both sides of the girder 33. The configuration of the step 10b other than the above can be the same as that of the first embodiment.

[0034] Fourth Embodiment As shown in Fig. 6, the staircase 130 according to the fourth embodiment is a staircase in which both end faces of the tread 10c are supported. The staircase 130 is an open-type staircase without risers. In the staircase 130, the tread 10c is fixed to a pair of side beams 34, 35 on the left and right. The side beams 34, 35 are installed from the floor surface to the framework of the upper floor.

[0035] Both end faces of the step plate 10c are fixed to a pair of side girders 34, 35. Therefore, the width of the step plate 10c and the distance between the pair of side girders 34, 35 are approximately the same. Since both end faces of the step plate 10c are fixed by the pair of side girders 34, 35, the thickness of the step plate 10c can be made smaller. Other than the above, the configuration of the step plate 10c can be the same as that of the first embodiment.

[0036] The above describes the staircase having the step plate according to the embodiment of the present disclosure. However, the present disclosure is not limited to the above embodiment and can be modified as appropriate. The step plate according to the present disclosure can be applied to stairs other than cantilever stairs and open-type stairs. For example, the step plate according to the present disclosure can be applied to stairs having risers. EXAMPLES

[0037] The present disclosure will be described in more detail below based on examples, but the present disclosure is not limited to these examples.

[0038] [Sample Preparation] Example 1 A sample having a length of 125±5 mm, a width of 13.0±0.5 mm, and a thickness of 2±0.5 mm was molded using CFRP containing pitch-based carbon fibers and epoxy resin. The carbon fibers were oriented such that the angle between the length direction and the orientation direction was 0°. A sample according to Example 2 was also prepared in the same manner. The tensile modulus of the carbon fibers was 720-800 GPa, and the tensile strength was 2500-3000 MPa.

[0039] Example 3 A sample according to Example 3 was produced in the same manner as in Example 1, except that the thickness was set to 4±0.5 mm.

[0040] Example 4 A sample according to Example 4 was produced in the same manner as in Example 1, except that the thickness was set to 4±0.5 mm and the orientation direction of the carbon fibers was set to an angle of 90° with the length direction.

[0041] Comparative Example 1 Except for using a CFRP containing PAN (polyacrylonitrile)-based carbon fiber, a sample according to Comparative Example 1 was produced in the same manner as in Example 1. The tensile modulus of the carbon fiber was 235 to 255 GPa, and the tensile strength was 3000 to 4000 MPa.

[0042] Comparative Example 2 A sample of Comparative Example 2 was produced in the same manner as in Example 1, except that a CFRP containing the same type of PAN-based carbon fiber as in Comparative Example 1 was used, the length was set to 100 mm, and the orientation direction of the carbon fiber was set at an angle of 90° with the length direction.

[0043] [Combustion test] A combustion test was carried out using the samples according to the above-mentioned Examples and Comparative Examples. The combustion test was a horizontal combustion test in accordance with UL94HB, a standard for evaluating the combustion characteristics of plastic materials. Specifically, the test was carried out according to the following procedure, with reference to JIS K 6911 General Test Method for Thermosetting Plastics 5.24 Flame Resistance C Method. First, the test piece was held horizontally and exposed to a 20 mm flame (40 mm flame for Example 2 only) for 30 seconds, and the fire resistance was evaluated based on the burning rate from the 25 mm mark to the 100 mm mark. Since the sample length of Comparative Example 2 was 100 mm, the above-mentioned gauge distance was set to 75 / 2 mm. The results are shown in Table 1 below.

[0044] [Table 1]

[0045] In all examples and comparative examples, the flame went out naturally, so the burning rate was calculated based on the time it took for the flame to go out. The UL94HB criteria are that the burning rate is 40 mm / min or less when the thickness of the test piece is 3 mm or more. Similarly, the burning rate is 75 mm / min or less when the thickness of the test piece is less than 3 mm. As shown in Table 1, all examples and comparative examples met the UL94HB criteria.

[0046] [Evaluation of thermal behavior of sample surface] The sample was observed during burning with a thermo camera (fixed-point observation: infrared thermography FLIR T630SC, manufactured by FLIR Systems, real-time measurement: infrared thermography testo868, manufactured by Testo Co., Ltd.) while taking video of the sample, and the thermal behavior of the sample surface was recorded. The results are shown in Figures 7 and 8. The details are as follows.

[0047] In Example 1, a combustion reaction occurred at the end after contact with the flame. The sample became red hot, but the burning area did not reach the 25 mm mark. The flame naturally went out 2 seconds after it was removed. Scorch marks were generated in the area where the flame rose. The scorch marks extended about 12 mm from the end where the flame was contacted. According to infrared thermography, the temperature of the area where the flame was contacted dropped to 150°C about 30 seconds after the flame was removed.

[0048] In Example 2, a combustion reaction occurred from the end after contact with the flame. The sample became red hot, and the burning area spread to the 25 mm marked line. The flame naturally went out 11 seconds after the flame was removed. Scorch marks were generated in the area where the flame rose. The scorch marks extended about 40 mm from the end where the flame was contacted. Thermography confirmed that heat spread in the direction of the carbon fiber orientation immediately after contact with the flame. The temperature of the area where the flame was contacted dropped to 150°C about 30 seconds after the flame was removed.

[0049] In Example 3, a combustion reaction occurred from the end after contact with the flame. However, the flame was smaller than in Example 1. The sample became red hot, but the burning area did not reach the 25 mm mark. The flame naturally went out less than one second after the flame was removed. A scorch mark occurred in the area where the flame rose. The scorch mark extended about 12 mm from the end where the flame was contacted. Thermography confirmed that heat spread over a narrower area than in Example 1 immediately after contact with the flame. The temperature of the area where the flame was contacted dropped to 150°C about 15 seconds after the flame was removed.

[0050] In Example 4, a combustion reaction occurred from the end after contact with the flame. The sample became red hot, but the burning area did not reach the 25 mm mark. After the flame was removed, the flame was maintained in the fiber direction and naturally went out after 55 seconds. A scorch mark was generated in the area where the flame rose. The scorch mark was about 20 mm from the end of the flame. Thermography confirmed that heat spread in the orientation direction of the carbon fiber immediately after contact with the flame, but did not spread in a direction perpendicular to the orientation direction. The temperature of the area where the flame was contacted dropped to 150°C about 75 seconds after the flame was removed.

[0051] In Comparative Example 1, a combustion reaction occurred from the end after contact with the flame. The sample became red hot and the burning range expanded, and the burning range spread beyond the 25 mm mark. The flame naturally went out 23 seconds after the flame was removed. The burned sample had fibers remaining over a distance of about 37 mm from the end of the flame, as if they had been torn. Thermography showed that the range of temperatures above 400°C was large compared to Example 1, and the range of temperatures from 150 to 200°C was narrow. The temperature of the area where the flame was contacted dropped to 150°C about 50 seconds after the flame was removed.

[0052] In Comparative Example 2, a combustion reaction occurred from the end after contact with the flame. The sample became red hot and the burning range expanded, and the burning range spread beyond the 25 mm mark and burned down. The fire continued to spread for 60 seconds after the flame separated, and after spreading by about 10 to 20 mm, the fire naturally went out. Thermography showed that the range above 400°C was larger than in Example 4, and the spread of heat below 200°C was similar. The temperature of the part where the flame had been contacted dropped to 150°C about 55 seconds after the flame went out.

[0053] From the above, it was confirmed that the samples of each Example using pitch-based carbon fiber have superior fire resistance compared to the samples of each Comparative Example using PAN-based carbon fiber. It was confirmed that by making the sample thickness 4 mm, the combustion range is narrower than when the thickness is 2 mm, and the temperature drop after the flame is released is also faster. It was confirmed that by orienting the carbon fiber in the longitudinal direction of the sample, heat is conducted in the longitudinal direction, and the time until spontaneous flame extinguishing is short. [Explanation of symbols]

[0054] 100, 110, 120, 130 stairs, 10, 10a, 10b, 10c treads

Claims

1. A tread for use on a staircase, It is made of carbon fiber reinforced plastic, The tensile modulus of the carbon fibers constituting the carbon fiber reinforced plastic is 600 GPa or more, The tensile strength of the carbon fiber is 2500 MPa or more.

2. 2. The tread of claim 1, wherein the carbon fiber is a pitch-based carbon fiber.

3. The footboard according to claim 1 or 2, wherein the carbon fiber reinforced plastic contains at least one of a cyanate ester, a phenol, a polyimide resin, and a flame retardant.

4. 3. The footboard according to claim 1, wherein a fiber volume content of the carbon fibers in the carbon fiber reinforced plastic is 50% or more and 80% or less.

5. The footboard according to claim 1 or 2, wherein the carbon fibers are aligned along the longitudinal direction of the footboard.

6. The step plate according to claim 1 or 2, wherein the thickness of the step plate is 4 mm or more.

7. The step plate according to claim 6, wherein the length of the step plate in the longitudinal direction is 750 mm or more and the length of the step plate in the lateral direction is 150 mm or more.

8. A staircase using the tread according to claim 1 or 2.

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