Water-permeable sheet, plate member, formwork, and method of manufacturing concrete products

Abstract

To provide a water-permeable sheet with little fluffing after being removed from a mold. [Solution] A water-permeable sheet used in formwork for manufacturing concrete products, the water-permeable sheet having a first nonwoven fabric layer containing a first resin fiber and a second nonwoven fabric layer arranged on one side of the first nonwoven fabric layer and containing a second resin fiber, the 60° gloss value of the surface of the water-permeable sheet facing the second nonwoven fabric layer being 5.0 or higher.

Description

[Technical Field]

[0001] The present disclosure relates to a method for manufacturing a water-permeable sheet, a plate member, a formwork, and a concrete product. [Background technology]

[0002] Generally, concrete products are produced by assembling formwork made of metal such as iron or wood, and pouring a concrete precursor (a mixture containing cement, aggregate, and water) into the assembled formwork. The concrete precursor in the formwork hardens through a hydration reaction, resulting in a concrete product with high strength.

[0003] A technique for providing a water-permeable sheet on a formwork to properly drain excess water and air bubbles from the concrete precursor when the concrete precursor is hardened is known. For example, Patent Document 1 discloses a water-permeable sheet for formwork, which is an integrated unit of a filtration layer (I) made of heat-sealed nonwoven fabric and an air-permeable / water-permeable layer (II) also made of nonwoven fabric. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 6-143236 Summary of the Invention [Problem to be solved by the invention]

[0005] As described in Patent Document 1, by placing a water-permeable sheet on the surface of the formwork, excess water and air bubbles can be properly drained, resulting in a good concrete product. After the concrete precursor is hardened, the water-permeable sheet and formwork are usually removed from the hardened concrete (removed from the formwork). If fluffing occurs on the water-permeable sheet during this process, it becomes difficult to reuse the water-permeable sheet.

[0006] The present disclosure has been made in consideration of the above-mentioned circumstances, and has as its main object to provide a water-permeable sheet that generates little fluff after being removed from the mold. [Means for solving the problem]

[0007] The present disclosure provides a water-permeable sheet used in a formwork for manufacturing concrete products, the water-permeable sheet having a first nonwoven fabric layer containing first resin fibers and a second nonwoven fabric layer disposed on one side of the first nonwoven fabric layer and containing second resin fibers, wherein the 60° gloss value of the surface of the water-permeable sheet facing the second nonwoven fabric layer is 5.0 or greater.

[0008] The present disclosure provides a plate member used in a formwork for manufacturing concrete products, the plate member having a substrate and the above-mentioned water-permeable sheet, in which the substrate, the first nonwoven fabric layer, and the second nonwoven fabric layer are arranged in this order in the thickness direction.

[0009] The present disclosure provides a formwork for manufacturing concrete products, the formwork having a formwork body and the above-mentioned water-permeable sheet, in which the formwork body, the first nonwoven fabric layer, and the second nonwoven fabric layer are arranged in this order in the thickness direction.

[0010] The present disclosure provides a method for manufacturing a concrete product, which includes a preparation step of preparing a formwork, and a hardening step of pouring a concrete precursor into the formwork and hardening the concrete precursor through a hydration reaction, wherein the formwork has a formwork body and the above-mentioned water-permeable sheet, and the formwork body, the first nonwoven fabric layer, and the second nonwoven fabric layer are arranged in this order in the thickness direction. [Effects of the Invention]

[0011] The present disclosure has the effect of providing a water-permeable sheet that has little fluffing after being removed from the mold. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a schematic cross-sectional view illustrating a water-permeable sheet according to the present disclosure. [Figure 2] 1 is a schematic cross-sectional view illustrating a water-permeable sheet according to the present disclosure. [Figure 3] 1A to 1C are schematic cross-sectional views illustrating a method for producing a water-permeable sheet according to the present disclosure. [Figure 4] 1 is a schematic cross-sectional view illustrating a plate member according to the present disclosure. [Figure 5] 1 is a schematic plan view illustrating a method for manufacturing a concrete product according to the present disclosure. [Figure 6] FIG. 5(b) is a cross-sectional view taken along the line AA in FIG. [Figure 7] FIG. 1 is a schematic perspective view illustrating a casting test using the water-permeable sheets obtained in the examples and comparative examples. DETAILED DESCRIPTION OF THE INVENTION

[0013] Below, embodiments will be described with reference to the drawings etc. However, the present disclosure can be implemented in many different forms and is not limited to the description of the embodiments exemplified below. Furthermore, to clarify the explanation, the drawings may show the width, thickness, and shape of each part schematically compared to the actual form, but this is merely an example and should not be construed as limiting.

[0014] In this specification, when describing a mode in which another component is disposed on a certain component, the term "above" or "below" refers to both a case in which another component is disposed directly above or below the certain component so as to be in contact with the component, and a case in which another component is disposed above or below the certain component with another component interposed therebetween, unless otherwise specified. Also, in this specification, when describing a mode in which another component is disposed on the surface of a certain component, the term "on the surface" refers to both a case in which another component is disposed directly above or below the certain component so as to be in contact with the component, and a case in which another component is disposed above or below the certain component with another component interposed therebetween, unless otherwise specified.

[0015] The methods for manufacturing the water-permeable sheet, plate member, formwork, and concrete product according to the present disclosure will be described in detail below.

[0016] A. Permeable sheet 1 is a schematic cross-sectional view illustrating a water-permeable sheet according to the present disclosure. As shown in FIG. 1, the water-permeable sheet 10 is T The water-permeable sheet 10 has a first nonwoven fabric layer 1 and a second nonwoven fabric layer 2 arranged along the line S1. Another feature of the present disclosure is that the 60° gloss value of the surface S1 of the water-permeable sheet 10 facing the second nonwoven fabric layer 2 is 5.0 or more.

[0017] According to the present disclosure, when the 60° gloss value of the surface of the water-permeable sheet facing the second nonwoven fabric layer is within a predetermined range, the water-permeable sheet has less fuzz after being removed from the form. As described above, after the concrete precursor is hardened, the water-permeable sheet and formwork are usually removed from the hardened concrete (removed from the form). If fuzzing occurs in the water-permeable sheet at this time, it becomes difficult to reuse the water-permeable sheet. Furthermore, if fuzzing occurs in the water-permeable sheet, it is possible that fibers from the water-permeable sheet will remain in the hardened concrete. Therefore, there is a demand for a water-permeable sheet that has less fuzz after being removed from the form.

[0018] Water-permeable sheets typically have resin fibers on their surfaces, resulting in a low 60° gloss value. In contrast, the water-permeable sheets of the present disclosure have a high 60° gloss value. For example, as shown in FIG. 3 (described later), when joining a first nonwoven fabric sheet 1a and a second nonwoven fabric sheet 2a, a slip sheet X functioning as an auxiliary film can be placed between the second nonwoven fabric sheet 2a and the heating roller R1 to smooth the surface of the second nonwoven fabric sheet 2a. This increases the 60° gloss value of the surface of the water-permeable sheet facing the second nonwoven fabric layer, and the second resin fibers are uniformly heat-fused on the surface facing the second nonwoven fabric layer, resulting in a water-permeable sheet with less fuzz after demolding. This facilitates reuse of the water-permeable sheet. Furthermore, this method can prevent fibers from remaining in hardened concrete.

[0019] 1. Characteristics of permeable sheets (1) 60° gloss value In the present disclosure, the 60° gloss value of the surface of the water-permeable sheet facing the second nonwoven fabric layer is typically 5.0 or greater. A 60° gloss value of 5.0 or greater results in a water-permeable sheet with less fuzz after demolding. Furthermore, "the surface of the water-permeable sheet facing the second nonwoven fabric layer" refers to the surface of the water-permeable sheet that is located on the opposite side of the second nonwoven fabric layer from the first nonwoven fabric layer. Furthermore, the surface of the water-permeable sheet facing the second nonwoven fabric layer typically corresponds to the surface that comes into contact with concrete.

[0020] The 60° gloss value may be 7.5 or more, 10.0 or more, 12.5 or more, 25.0 or more, 30.0 or more, or 35.0 or more. If the 60° gloss value is too low, it may be difficult to sufficiently suppress fuzzing after demolding. On the other hand, the 60° gloss value may be, for example, 60.0 or less, 50.0 or less, or 45.0 or less. Furthermore, from the viewpoint of preventing the concrete surface from becoming excessively smooth and reducing the designability, the 60° gloss value may be, for example, 30.0 or less.

[0021] The 60° gloss value is measured using a gloss meter according to JIS Z8741:1997. Specifically, the surface of the water-permeable sheet facing the second nonwoven fabric layer is placed on the gloss meter, and the 60° gloss value is read. The 60° gloss value is the average of values ​​measured at 10 random locations.

[0022] (2) Air permeability The water-permeable sheet of the present disclosure preferably has an air permeability of 3.0 μm / (Pa·s) or more, because this can prevent the concrete from becoming deformed, such as with pitting. The air permeability may be 10.0 μm / (Pa·s) or more, 100 μm / (Pa·s) or more, or even 1000 μm / (Pa·s) or more.

[0023] The air permeability is measured using an Oken air permeability tester in accordance with JIS P8117:2009. Specifically, the air permeability resistance of the water-permeable sheet is K Measure the air permeability P and calculate the ISO air permeability P (P = 127 / t K ) The air permeability is calculated by taking the average of five measurements. K The smaller the value, the greater the air permeability value.

[0024] 2. Layer structure of permeable sheet The water-permeable sheet according to the present disclosure includes a first nonwoven fabric layer containing first resin fibers and a second nonwoven fabric layer disposed on one surface of the first nonwoven fabric layer. The first and second nonwoven fabric layers may be disposed so as to be in contact with each other, or may be disposed with another layer interposed therebetween.

[0025] (1) First nonwoven layer The first nonwoven fabric layer contains first resin fibers and has the function of discharging excess water that migrates from the second nonwoven fabric layer to the outside. The resin fibers contained in the first nonwoven fabric layer are referred to as first resin fibers.

[0026] (i) First resin fiber The first nonwoven fabric layer includes first resin fibers. Examples of the first resin fibers include polyolefin fibers and polyester fibers. Examples of the polyolefin fibers include polyethylene fibers (PE fibers), polypropylene fibers (PP fibers), and ethylene-propylene copolymer fibers (PE-PP fibers). Examples of the polyester fibers include polyethylene terephthalate fibers (PET fibers).

[0027] The first resin fiber may be a sheath-core fiber. A sheath-core fiber is a fiber having a core and a sheath that surrounds the core. The melting point of the resin that constitutes the core is usually higher than the melting point of the resin that constitutes the sheath. Furthermore, the resin that constitutes the core and the resin that constitutes the sheath are usually different types of resin.

[0028] Examples of resins constituting the core include polyolefin resins such as polypropylene and ethylene-propylene copolymer, and polyester resins such as polyethylene terephthalate. Among these, polypropylene is preferred as the resin constituting the core. On the other hand, examples of resins constituting the sheath include polyolefins such as polyethylene, polypropylene, and ethylene-propylene copolymer, and polyesters such as polyethylene terephthalate.

[0029] Examples of combinations of the resin constituting the core and the resin constituting the sheath include sheath-core fibers (PET / PE) with a polyethylene terephthalate core and a polyethylene sheath, and sheath-core fibers (PP / PE) with a polypropylene core and a polyethylene sheath. Of these, it is preferable that the first nonwoven fabric layer has sheath-core fibers (PP / PE) or sheath-core fibers (PET / PE) as the first resin fibers.

[0030] The first nonwoven fabric layer may contain only one type of resin fiber as the first resin fiber, or may contain two or more types of resin fibers. When the first nonwoven fabric layer contains two or more types of resin fibers, they are preferably blended.

[0031] The first nonwoven fabric layer may contain, as the first resin fibers, highly hydrophilic sheath-core fibers (PP / PE) in which the sheath-core fibers (PP / PE) have a polypropylene (PP) core and a polyethylene (PE) sheath and are coated with a surfactant, and sheath-core fibers (PP / PE) have a polypropylene (PP) core and a polyethylene (PE) sheath. The proportion of the highly hydrophilic sheath-core fibers (PP / PE) to the total of the highly hydrophilic sheath-core fibers (PP / PE) and the sheath-core fibers (PP / PE) is, for example, 20% by mass or more and 80% by mass or less, or may be 40% by mass or more and 60% by mass or less.

[0032] The first nonwoven fabric layer may contain, as the first resin fibers, polypropylene fibers (PP) and sheath-core fibers (PP / PE) with a polypropylene (PP) core and a polyethylene (PE) sheath. The proportion of the sheath-core fibers (PP / PE) to the total of the polypropylene fibers (PP) and the sheath-core fibers (PP / PE) is, for example, 20% by mass or more and 80% by mass or less, or may be 40% by mass or more and 60% by mass or less.

[0033] The first resin fibers are preferably not swellable fibers (fibers having OH groups). For example, fibers such as rayon have OH groups, so they absorb water and swell. When they absorb water and swell, the mesh of the first nonwoven fabric layer narrows, reducing water permeability. The first resin fibers are usually non-swellable fibers (fibers without OH groups).

[0034] The first resin fibers are partially heat-welded to each other to form a nonwoven fabric, such as a spunbonded nonwoven fabric, a meltblown nonwoven fabric, an airlaid nonwoven fabric, a flash-spun nonwoven fabric, a chemically bonded nonwoven fabric, a needle-punched nonwoven fabric, a stitch-bonded nonwoven fabric, a thermally bonded nonwoven fabric, or a burst fiber nonwoven fabric.

[0035] (ii) surfactants The first nonwoven fabric layer may contain a surfactant. A surfactant is typically a compound having a hydrophilic region and a hydrophobic region. Since the first resin fiber is typically hydrophobic, the hydrophobic region of the surfactant is disposed on the surface side of the first resin fiber, exposing the hydrophilic region of the surfactant. This improves the hydrophilicity of the first nonwoven fabric layer. The surfactant may be used alone or in combination of two or more. On the other hand, the first nonwoven fabric layer does not necessarily contain a surfactant.

[0036] Examples of surfactants include cationic surfactants, anionic surfactants, amphoteric surfactants, and nonionic surfactants. Cationic surfactants are surfactants that become cations when dissociated in water, and examples thereof include alkyltrimethylammonium salts, dialkyldimethylammonium salts, and alkylbenzyldimethylammonium salts. Anionic surfactants are surfactants that become anions when dissociated in water, and examples thereof include fatty acid sodium salts, monoalkyl sulfates, alkyl polyoxyethylene sulfates, alkylbenzene sulfonates, and monoalkyl phosphates.

[0037] Amphoteric surfactants are surfactants that have both anionic and cationic moieties in the molecule, and become cationic, amphoteric, or anionic depending on the pH of the solution, such as alkyldimethylamine oxide and alkylcarboxybetaine. Nonionic surfactants are surfactants that have a non-ionizable hydrophilic portion, such as polyoxyethylene alkyl ether, fatty acid sorbitan ester, alkyl polyglucoside, fatty acid diethanolamide, and alkyl monoglyceryl ether.

[0038] The content of the surfactant in the first nonwoven fabric layer is, for example, 0.1 g / m 2 More than 300g / m 2The surfactant preferably coats the first resin fibers. For example, the surfactant is attached to the first resin fibers so as to coat the surfaces of the first resin fibers by surface-treating the first resin fibers. Examples of surface-treating methods include immersing the fibers in a treatment solution prepared by diluting the surfactant with distilled water, and applying a treatment solution prepared by diluting the surfactant with distilled water.

[0039] (iii) First nonwoven layer When the first nonwoven fabric layer contains a surfactant, the second nonwoven fabric layer does not need to contain a hydrophilic agent. By increasing the hydrophilicity of the first nonwoven fabric layer, the water absorbency of the second nonwoven fabric layer can be improved even if the second nonwoven fabric layer does not contain a hydrophilic agent. Alternatively, the first nonwoven fabric layer may contain a surfactant, and the second nonwoven fabric layer may further contain a hydrophilic agent. In this case, the hydrophilic agent may be kneaded into the second resin fibers or may coat the second resin fibers. On the other hand, when the first nonwoven fabric layer does not contain a surfactant, it is preferable that the second nonwoven fabric layer contains a hydrophilic agent. In this case, the hydrophilic agent may be kneaded into the second resin fibers or may coat the second resin fibers.

[0040] The thickness of the first nonwoven fabric layer is, for example, 0.5 mm or more and 3.0 mm or less, and may be 1.0 mm or more and 2.0 mm or less. The basis weight of the first nonwoven fabric layer is, for example, 100 g / m 2 More than 300g / m 2 less than 150 g / m 2 More than 250g / m 2 It may be the following:

[0041] (2) Second nonwoven layer The second nonwoven fabric layer is disposed on one side of the first nonwoven fabric layer and contains second resin fibers, which have the function of retaining cement particles while allowing excess water to pass through. The resin fibers contained in the second nonwoven fabric layer are referred to as second resin fibers.

[0042] (i) Second resin fiber The second nonwoven fabric layer includes second resin fibers. Examples of the second resin fibers include polyolefin fibers and polyester fibers. Examples of the polyolefin fibers include polyethylene fibers (PE fibers), polypropylene fibers (PP fibers), and ethylene-propylene copolymer fibers (PE-PP fibers). Examples of the polyester fibers include polyethylene terephthalate fibers (PET fibers).

[0043] The second resin fiber may be a sheath-core fiber. Details of the sheath-core fiber are the same as those of the first resin fiber described above, and therefore will not be described here. The second nonwoven fabric layer may contain only one type of resin fiber as the second resin fiber, or may contain two or more types of resin fibers. When the second nonwoven fabric layer contains two or more types of resin fibers, they are preferably blended.

[0044] The second nonwoven fabric layer may contain, as the second resin fiber, a core-sheath fiber having a polypropylene core and a polyethylene sheath. The second nonwoven fabric layer may also contain, as the second resin fiber, polyethylene fiber. Polyethylene fiber has a relatively low melting point, which can make it difficult to produce a water-permeable sheet. In contrast, by arranging an interleaf paper X, as shown in FIG. 3 (described later), a good second nonwoven fabric layer can be produced even when polyethylene fiber is used.

[0045] (ii) Hydrophilic Agent The second nonwoven fabric layer may contain a hydrophilic agent. Adding a hydrophilic agent makes it easier for excess water from the concrete precursor to pass through. Furthermore, if the difference in solubility parameters between the second resin fiber and the hydrophilic agent is small, the hydrophilic agent will easily become entangled with the second resin fiber, and hydrophilicity will likely be improved. On the other hand, if the difference in solubility parameters between the two is large, it is presumed that the hydrophilic agent will not easily become entangled with the second resin fiber, and hydrophilicity will likely be reduced. The hydrophilic agent may be used alone or in combination of two or more types. On the other hand, the second nonwoven fabric layer does not have to contain a hydrophilic agent.

[0046] Examples of hydrophilic agents include squalane-based hydrophilic agents, polyester-based hydrophilic agents, olefin-based hydrophilic agents, and nonionic silicone polymers. Squalane-based hydrophilic agents are hydrophilic agents containing squalane or its derivatives. Squalane is also known as a moisturizing agent, and animal-based squalane extracted from shark liver oil and plant-based squalane extracted from plants such as olives are known. Examples of squalane-based hydrophilic agents include Queensetter SSQ-2 manufactured by Kotani Chemical Industry Co., Ltd.

[0047] An example of a polyester-based hydrophilic agent is Nicepol PR-99 manufactured by Nicca Chemical Co., Ltd. An example of an olefin-based hydrophilic agent is Nicepol NW-543 manufactured by Nicca Chemical Co., Ltd. An example of a nonionic silicone polymer is Queenset PSO-7000 manufactured by Kotani Chemical Industry Co., Ltd.

[0048] The hydrophilic agent may be a thermally crosslinkable agent. A thermally crosslinkable hydrophilic agent is polymerized by a crosslinking reaction caused by heat to form a network molecular structure that is insoluble in water, and thus entangles with the fibers, making it difficult for the agent to flow out, allowing the agent to be reused as a water-permeable sheet.

[0049] The content of the hydrophilic agent in the second nonwoven fabric layer is, for example, 0.1 g / m 2 More than 100g / m 2 The hydrophilic agent may also coat the second resin fiber. For example, by subjecting the second resin fiber to a hydrophilic treatment, the hydrophilic agent is attached so as to coat the surface of the second resin fiber. Examples of hydrophilic treatment include a method of immersing the fiber in a hydrophilic treatment solution prepared by diluting the hydrophilic agent with distilled water, and a method of applying a hydrophilic treatment solution prepared by diluting the hydrophilic agent with distilled water. On the other hand, the hydrophilic agent may be kneaded into the second resin fiber. That is, the hydrophilic agent may be present inside the second resin fiber.

[0050] When the second nonwoven fabric layer contains a hydrophilic agent, the combination of the second resin fiber and the hydrophilic agent is not particularly limited, and for example, any combination of the second resin fiber and the hydrophilic agent described above can be used. On the other hand, the second resin fiber and the hydrophilic agent may be, for example, the following combinations.

[0051] (iii) Second nonwoven layer The thickness of the second nonwoven fabric layer is, for example, 0.03 mm or more and 0.5 mm or less, and may be 0.05 mm or more and 0.3 mm or less. The basis weight of the second nonwoven fabric layer is, for example, 15 g / m 2 More than 100g / m 2 less than 20 g / m 2 More than 80g / m 2 or less. If the basis weight of the second nonwoven fabric layer is too small, concrete particles are likely to penetrate, and if the basis weight of the second nonwoven fabric layer is too large, it becomes difficult to absorb excess water. In addition, the basis weight of the second nonwoven fabric layer is preferably less than that of the first nonwoven fabric layer. The difference between the basis weights of the first and second nonwoven fabric layers is, for example, 50 g / m 2 or more, and 100 g / m 2 It may be more than that.

[0052] In the present disclosure, the first nonwoven fabric layer and the second nonwoven fabric layer may be in direct contact with each other. In this case, the first nonwoven fabric layer and the second nonwoven fabric layer are preferably welded to each other at the interface between the two layers. Alternatively, the first nonwoven fabric layer and the second nonwoven fabric layer may be laminated via an adhesive layer. The adhesive layer is preferably patterned. The adhesive layer preferably contains, for example, a hot melt adhesive.

[0053] (3) Other demographics As shown in Fig. 2, the water-permeable sheet 10 may have an adhesive layer 3 on the surface of the first nonwoven fabric layer 1 opposite to the second nonwoven fabric layer 2. The adhesive layer 3 is preferably attached to a substrate or a form body (for example, the substrate 11 or form body 21 in Fig. 5(a)).

[0054] Examples of adhesives used in the adhesive layer include acrylic resin adhesives, urethane resin adhesives, silicone resin adhesives, vinyl chloride resin adhesives, and rubber adhesives. The adhesive layer may be a solid layer or a porous layer. The thickness of the adhesive layer is not particularly limited, but is, for example, 1 μm or more and 100 μm or less.

[0055] As shown in FIG. 2, the water-permeable sheet 10 may have a release layer 4 on the surface of the adhesive layer 3 opposite the first nonwoven fabric layer 1. By providing the release layer 4, the adhesive layer 3 can be protected until it is attached to a substrate or a form body (for example, the substrate 11 or the form body 21 in FIG. 5(a)). Examples of materials for the release layer 4 include paper, resin, and metal. One example of a method for forming an adhesive layer is to apply an adhesive layer-forming composition to the release layer 4, dry it, and then laminate the surface of the first nonwoven fabric layer 1 opposite the second nonwoven fabric layer 2. Another example of a method for forming an adhesive layer is to attach a sheet-like adhesive layer to the surface of the first nonwoven fabric layer 1 opposite the second nonwoven fabric layer 2.

[0056] 4.Water-permeable sheet The thickness of the water-permeable sheet in the present disclosure is not particularly limited, but may be, for example, 0.5 mm or more and 3.0 mm or less, or 1.0 mm or more and 2.0 mm or less. The water-permeable sheet is used in a formwork for producing a concrete product.

[0057] 5. Manufacturing method of water-permeable sheet The method for producing a water-permeable sheet according to the present disclosure is not particularly limited. For example, as shown in FIG. 3, a method may be used in which a precursor laminate including a first nonwoven fabric sheet 1a containing first resin fibers and a second nonwoven fabric sheet 2a containing second resin fibers is heated and pressurized using a heated roller R1. The roller R2 is preferably unheated. The heating and pressurization densifies the first nonwoven fabric sheet 1a and the second nonwoven fabric sheet 2a, and simultaneously heat-welds them to each other, thereby obtaining a water-permeable sheet having a first nonwoven fabric layer 1 and a second nonwoven fabric layer 2. The heating temperature of the heated roller may be, for example, 150°C or higher and 190°C or lower, or may be 160°C or higher and 180°C or lower.

[0058] In particular, as shown in FIG. 3 , by applying heat and pressure to the second nonwoven fabric sheet 2a with a heating roller R1 via an interleaving paper X that functions as an auxiliary film, the surface of the second nonwoven fabric layer 2 is smoothed, resulting in a water-permeable sheet having a second nonwoven fabric layer 2 with a high 60° gloss value. Examples of interleaving paper include resin sheets. Resins used in resin sheets are not particularly limited, but examples include polyethylene terephthalate (PET). The surface of the resin sheet may be smooth or may have irregularities. Having some irregularities on the surface of the resin sheet can prevent the surface of the second nonwoven fabric layer from becoming excessively smooth. If the surface of the second nonwoven fabric layer becomes excessively smooth, the surface of the concrete may also become excessively smooth, which may reduce the design quality. Therefore, using an irregular resin sheet can prevent the surface of the concrete from becoming excessively smooth.

[0059] For example, if the second nonwoven fabric layer contains polyethylene fibers as the second resin fibers, it may be difficult to produce a water-permeable sheet due to the relatively low melting point of polyethylene fibers. For example, lowering the temperature of the heating roller may result in insufficient bonding between the first and second nonwoven fabric sheets. Conversely, raising the temperature of the heating roller may cause the polyethylene fibers to melt and become entangled in the heating roller. In contrast, as shown in FIG. 3, by applying heat and pressure to the second nonwoven fabric sheet 2a with the heating roller R1 via an interleaving paper X that functions as an auxiliary film, it is possible to prevent the polyethylene fibers from becoming entangled in the heating roller R1 even when the temperature of the heating roller R1 is raised, and furthermore, the first nonwoven fabric sheet 1a and the second nonwoven fabric sheet 2a can be sufficiently bonded together.

[0060] B. Plate member The plate member of the present disclosure is a plate member used in a formwork for manufacturing concrete products, and the plate member has a substrate and the above-mentioned water-permeable sheet, and in the thickness direction has the substrate, the first nonwoven fabric layer, and the second nonwoven fabric layer, in this order.

[0061] 4, the plate member 20 has a substrate 11 and a water-permeable sheet 10. The plate member 20 has a thickness direction D T 4 has, in this order, a substrate 11, a first nonwoven fabric layer 1, and a second nonwoven fabric layer 2. The water-permeable sheet 10 shown in Fig. 4 has an adhesive layer 3 on the surface of the first nonwoven fabric layer 1 opposite to the second nonwoven fabric layer 2, and is disposed so that the adhesive layer 3 and the substrate 11 face each other. Although not particularly shown, an adhesive layer may be provided on at least one of the water-permeable sheet and the substrate when the water-permeable sheet and the substrate are bonded together.

[0062] According to the present disclosure, by using the above-described water-permeable sheet, a plate member with less fuzz after demolding can be obtained. Note that the water-permeable sheet is the same as that described above in "A. Water-permeable sheet."

[0063] The substrate in the present disclosure is not particularly limited, but examples thereof include wood substrates and metal substrates. Examples of wood substrates include wood veneers, wood plywood, particle boards, and wood fiber boards. Examples of metal substrates include iron plates and steel plates.

[0064] C. Formwork The formwork in the present disclosure is a formwork for manufacturing concrete products, and the formwork has a formwork body and the above-mentioned water-permeable sheet, and in the thickness direction has the formwork body, the first nonwoven fabric layer, and the second nonwoven fabric layer, in this order.

[0065] Specifically, as shown in Figure 5(a), the form 30 has a form body 21 and a water-permeable sheet 10. The form 30 also has, in the thickness direction, the form body 21, a first nonwoven fabric layer 1, and a second nonwoven fabric layer 2, in this order. That is, the first nonwoven fabric layer 1 is disposed between the form body 21 and the second nonwoven fabric layer 2.

[0066] According to the present disclosure, by using the above-mentioned water-permeable sheet, a formwork with less fuzzing after demolding can be obtained. Note that the water-permeable sheet is the same as that described above in "A. Water-permeable sheet."

[0067] The formwork body in the present disclosure is not particularly limited, but examples thereof include wooden formwork and metal formwork. As shown in Fig. 5(a), the formwork body 21 may be formed by combining a plurality of substrates 21. That is, the formwork 30 may be formed by combining a plurality of plate members (members having substrates 21 and water-permeable sheets 10).

[0068] D. Manufacturing methods for concrete products The method for manufacturing a concrete product according to the present disclosure includes a preparation step of preparing a formwork, and a hardening step of pouring a concrete precursor into the formwork and hardening the concrete precursor through a hydration reaction, wherein the formwork has a formwork body and the above-mentioned water-permeable sheet, and has, in the thickness direction, the formwork body, the first nonwoven fabric layer, and the second nonwoven fabric layer, in this order.

[0069] Specifically, as shown in FIG. 5(a), first, a formwork 30 is prepared (preparation step). The formwork 30 has a formwork main body 21 and a water-permeable sheet 10, and in the thickness direction, the formwork main body 21, a first nonwoven fabric layer 1, and a second nonwoven fabric layer 2, in that order. Next, as shown in FIG. 5(b), a concrete precursor 51 is poured into the formwork 30, and the concrete precursor 51 is hardened by a hydration reaction to obtain a concrete product 50 (hardening step). Furthermore, as shown in FIG. 6, excess water and air bubbles contained in the concrete precursor 51 are properly discharged via the water-permeable sheet 10.

[0070] According to the present disclosure, by using the above-described water-permeable sheet, a concrete product can be obtained with little residual fibers of the water-permeable sheet.

[0071] 1. Preparation process The preparation step in this disclosure is a step of preparing a formwork. The formwork is the same as that described above in "C. Formwork."

[0072] 2.Curing process The hardening step in the present disclosure is a step of pouring a concrete precursor into the formwork and hardening the concrete precursor through a hydration reaction.

[0073] The concrete precursor contains cement, aggregate, and water. Examples of cement include Portland cement. Examples of aggregate include sand, gravel, crushed stone, and crushed sand. The concrete precursor may also contain admixtures such as a water-reducing agent. The method for pouring the concrete precursor into the formwork is not particularly limited, and known methods can be used.

[0074] 3. Concrete products The method for producing a concrete product according to the present disclosure may include a peeling step of peeling the formwork from the concrete product after the hardening step. The uses of the concrete product according to the present disclosure are not particularly limited, and examples thereof include buildings, roads, dams, viaducts, tunnels, and port facilities.

[0075] The present disclosure is not limited to the above-described embodiments. The above-described embodiments are merely examples, and anything that has substantially the same configuration as the technical idea described in the claims of the present disclosure and exhibits similar effects is included within the technical scope of the present disclosure. [Example]

[0076] [Comparative Example 1] The nonwoven fabric sheet used for the first nonwoven fabric layer was a nonwoven fabric sheet (manufactured by Tsujitomi Co., Ltd., FTPP220, basis weight 220 g / m) containing 50 mass % of highly hydrophilic sheath-core fibers (PP / PE) in which the core-sheath fibers (PP / PE) had a polypropylene (PP) core and a polyethylene (PE) sheath and were coated with a surfactant, and 50 mass % of sheath-core fibers (PP / PE) in which the core-sheath fibers had a polypropylene (PP) core and a polyethylene (PE) sheath. 2 A nonwoven fabric sheet having a thickness of 1.366 mm was prepared for the second nonwoven fabric layer. A core-sheath fiber sheet with PP as the core and PE as the sheath (Thermal Bond PP / PE, manufactured by Shinwa Co., Ltd., 9540FOF, basis weight 40 g / m) was also prepared. 2 , thickness 0.169 mm) was prepared.

[0077] These nonwoven fabric sheets were each cut into a size of 5 cm x 10 cm and stacked. The resulting laminate was heated and pressed (10 kgf) using a pair of rubber rollers (only the rubber roller on the second nonwoven fabric sheet side was heated to 160°C). The conveying speed was 1.5 m / min. This resulted in a water-permeable sheet having a first nonwoven fabric layer and a second nonwoven fabric layer.

[0078] [Example 1] Two types of nonwoven fabric sheets were prepared in the same manner as in Comparative Example 1. These nonwoven fabric sheets were each cut to a size of 5 cm x 10 cm and stacked. Furthermore, a PET separator (PET75x1-J8, manufactured by Nippa Corporation, arithmetic mean height Sa 1.9 μm, 60° gloss value 104.0 (measurement surface: release coat side)) was stacked as an interleaf paper on the nonwoven fabric sheet used for the second nonwoven fabric layer. A water-permeable sheet was obtained in the same manner as in Comparative Example 1, except that the resulting laminate was used.

[0079] [Example 2] The nonwoven fabric sheet used for the second nonwoven fabric layer was a nonwoven fabric sheet containing PE fiber alone (Maeda Kosen Co., Ltd., SE-2030E, basis weight 30 g / m 2 , thickness 0.22 mm) was used, Example 1 In the same manner, a water-permeable sheet was obtained.

[0080] [Example 3] A water-permeable sheet was obtained in the same manner as in Example 2, except that the temperature of the rubber rollers was changed from 160°C to 180°C and the number of times heating and pressing by the pair of rubber rollers was changed from once to three times.

[0081] [Reference example 1] A water-permeable sheet was obtained in the same manner as in Example 3, except that the number of nonwoven fabric sheets used in the second nonwoven fabric layer was changed from one to two.

[0082] [Example 4] Except for the use of a matte film (Toray Industries, Lumirror 50X42G, arithmetic mean height Sa 1.6 μm, 60° gloss value 14.1) as the interleaf, Example 2 In the same manner, a water-permeable sheet was obtained.

[0083] [Example 5] Except for the use of a matte film (Toray Industries, Lumirror 50X44, arithmetic mean height Sa 3.7 μm, 60° gloss value 47.1) as the interleaf, Example 2 In the same manner, a water-permeable sheet was obtained.

[0084] [evaluation] (gross value) The 60° gloss value of the surface of the water-permeable sheet obtained in each Example and Comparative Example facing the second nonwoven fabric layer was measured. The 60° gloss value was measured using a gloss meter (a micro-TRI-gloss gloss meter manufactured by BYK) in accordance with JIS Z8741:1997. Specifically, the surface of the water-permeable sheet facing the second nonwoven fabric layer was placed on the gloss meter, and the 60° gloss value was read. The 60° gloss value was calculated by averaging values ​​measured at 10 random locations. The results are shown in Table 1.

[0085] (Air permeability) The air permeability of the water-permeable sheets obtained in each Example and Comparative Example was measured. The air permeability was measured using an Oken-type air permeability smoothness tester (KG2S manufactured by Asahi Seiko Co., Ltd.) according to a method in accordance with JIS P8117:2009. Specifically, the air permeability resistance t K The ISO air permeability P was calculated (P = 127 / t K The air permeability was calculated by averaging five measurements. The results are shown in Table 1.

[0086] (Pouring test) A casting test was conducted using the water-permeable sheets obtained in each example and comparative example. Specifically, as shown in Figure 7, two plate members were prepared by cutting the water-permeable sheet to a size of 100 mm x 50 mm and attaching it to a plywood board of the same size. The two plate members were arranged with a 20 mm gap between them so that the water-permeable sheets faced each other. Next, the positions of the two opposing plate members were fixed with two pieces of plywood (100 mm x 50 mm) to obtain a formwork. Ready-mixed concrete (60-minute quick-drying instant concrete manufactured by Toyo Materan Co., Ltd., mix ratio: 100 (concrete) / 18.2 (water)) was poured into the obtained formwork and pressed down with a medicine spoon. The concrete was allowed to harden at room temperature for three days, and then the formwork was removed from the hardened concrete.

[0087] The fluffing of the water-permeable sheet in the removed formwork was evaluated according to the following criteria. The results are shown in Table 1. 〇: 0 fluff △: 1 to 9 fluffs ×: 10 or more fluffs

[0088] The appearance of the hardened concrete was observed, and the number of pits (defective shapes) with a maximum diameter φ of 0.5 mm or more and less than 3.0 mm was counted and evaluated according to the following criteria. The results are shown in Table 1. ◎:0 pieces 〇:1 piece △: 2 or more and 4 or less ×: 5 or more and 9 or less ××: 10 or more avatars or avatars with a maximum diameter of 3.0 mm or more

[0089] [Table 1]

[0090] As shown in Table 1, Example 1 was able to suppress fuzzing compared to Comparative Example 1. This is presumably because the 60° gloss value of the surface of the water-permeable sheet facing the second nonwoven fabric layer was increased by disposing an interleaf paper when preparing the water-permeable sheet. Similar to Example 1, Examples 2 to 5 were also able to suppress fuzzing. Furthermore, Examples 1 to 5 were also able to suppress the occurrence of pockmarks. Note that Example 3 had a greater number of pockmarks than the other Examples. This is presumably because the high lamination temperature and the frequent densification with the rubber roller reduced the water absorption of the second nonwoven fabric layer. Reference Example 1 had a greater number of pockmarks than Example 3. However, fuzzing was also suppressed in Reference Example 1, and the occurrence of pockmarks can be sufficiently suppressed by, for example, adjusting the processing conditions. Furthermore, in Reference Example 1, the second nonwoven fabric layer can be made thicker, which may improve durability.

[0091] As described above, the present disclosure provides, for example, the following inventions.

[0092] [1] A water-permeable sheet used in a formwork for manufacturing concrete products, the water-permeable sheet has a first nonwoven fabric layer containing first resin fibers, and a second nonwoven fabric layer disposed on one surface of the first nonwoven fabric layer and containing second resin fibers; The water-permeable sheet has a 60° gloss value of 5.0 or more on the surface of the water-permeable sheet facing the second nonwoven fabric layer.

[0093] [2] The water-permeable sheet according to [1], wherein the 60° gloss value of the surface of the water-permeable sheet facing the second nonwoven fabric layer is 10.0 or more.

[0094] [3] The water-permeable sheet according to [1] or [2], wherein the water-permeable sheet has an air permeability of 3.0 μm / (Pa·s) or more.

[0095] [4] The water-permeable sheet according to any one of [1] to [3], wherein the water-permeable sheet has an air permeability of 15.0 μm / (Pa·s) or more.

[0096] [5] The water-permeable sheet according to any one of [1] to [4], wherein the first nonwoven fabric layer contains a surfactant.

[0097] [6] The water-permeable sheet according to [5], wherein the first resin fibers are coated with the surfactant.

[0098] [7] The water-permeable sheet according to [5] or [6], wherein the surfactant is at least one of a cationic surfactant, an anionic surfactant, an amphoteric surfactant, and a nonionic surfactant.

[0099] [8] A water-permeable sheet according to any one of [1] to [7], wherein the second nonwoven fabric layer contains, as the second resin fiber, a core-sheath fiber having a polypropylene core and a polyethylene sheath.

[0100] [9] The water-permeable sheet according to any one of [1] to [7], wherein the second nonwoven fabric layer contains polyethylene fibers as the second resin fibers.

[0101]

[10] A plate member used in a formwork for manufacturing concrete products, The plate member has a substrate and a water-permeable sheet according to any one of [1] to [9], A plate member in which the substrate, the first nonwoven fabric layer, and the second nonwoven fabric layer are arranged in this order in the thickness direction.

[0102]

[11] A formwork for producing concrete products, The formwork has a formwork body and a water-permeable sheet according to any one of [1] to [9], The form, in which the form body, the first nonwoven fabric layer, and the second nonwoven fabric layer are arranged in this order in the thickness direction.

[0103]

[12] The formwork described in

[11] , wherein the formwork body is constructed by combining a plurality of substrates.

[0104]

[13] a preparation step of preparing a formwork; a hardening step of pouring a concrete precursor into the formwork and hardening the concrete precursor through a hydration reaction; A method for manufacturing a concrete product comprising: The formwork has a formwork body and a water-permeable sheet according to any one of [1] to [9], A method for manufacturing a concrete product, wherein the formwork body, the first nonwoven fabric layer, and the second nonwoven fabric layer are arranged in this order in the thickness direction. [Explanation of symbols]

[0105] 1...First nonwoven fabric layer 2…Second nonwoven fabric layer 3 … Adhesive layer 4 … Release layer 10...Water-permeable sheet 20 … Plate member 30... Formwork

Claims

1. A water-permeable sheet used in a formwork for manufacturing concrete products, the water-permeable sheet includes a first nonwoven fabric layer containing first resin fibers, and a second nonwoven fabric layer disposed on one surface of the first nonwoven fabric layer and made of polyethylene fibers as second resin fibers; A water-permeable sheet, wherein the 60° gloss value of the surface of the water-permeable sheet facing the second nonwoven fabric layer is 5.0 or more.

2. The water-permeable sheet according to claim 1, wherein the 60° gloss value of the surface of the water-permeable sheet facing the second nonwoven fabric layer is 10.0 or more.

3. The water-permeable sheet according to claim 1, wherein the water-permeable sheet has an air permeability of 3.0 μm / (Pa·s) or more.

4. The water-permeable sheet according to claim 1, wherein the water-permeable sheet has an air permeability of 15.0 μm / (Pa·s) or more.

5. The water-permeable sheet according to claim 1 , wherein the first nonwoven fabric layer contains a surfactant.

6. The water-permeable sheet according to claim 5 , wherein the first resin fibers are coated with the surfactant.

7. 6. The water-permeable sheet according to claim 5, wherein the surfactant is at least one of a cationic surfactant, an anionic surfactant, an amphoteric surfactant, and a nonionic surfactant.

8. A plate member used in a formwork for manufacturing concrete products, The plate member has a substrate and the water-permeable sheet according to any one of claims 1 to 7, A plate member, comprising the substrate, the first nonwoven fabric layer, and the second nonwoven fabric layer arranged in this order in the thickness direction.

9. A formwork for producing concrete products, The formwork has a formwork body and the water-permeable sheet according to any one of claims 1 to 7, A formwork in which the formwork body, the first nonwoven fabric layer, and the second nonwoven fabric layer are arranged in this order in the thickness direction.

10. The formwork according to claim 9 , wherein the formwork body is formed by combining a plurality of substrates.

11. a preparation step of preparing a formwork; a hardening step of pouring a concrete precursor into the formwork and hardening the concrete precursor through a hydration reaction; A method for manufacturing a concrete product comprising: The formwork has a formwork body and the water-permeable sheet according to any one of claims 1 to 7, A method for manufacturing a concrete product, in which the formwork body, the first nonwoven fabric layer, and the second nonwoven fabric layer are arranged in this order in the thickness direction.

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