Method for manufacturing permeable sheets, plate members, formwork, and concrete products

Abstract

The present invention provides a permeable sheet used in molds for manufacturing concrete products, which suppresses the occurrence of shape defects such as pitting on the surface of concrete products, while also providing a permeable sheet that exhibits minimal fuzzing after demolding. [Solution] The water-permeable sheet comprises a first nonwoven fabric layer containing first resin fibers and a second nonwoven fabric layer containing second resin fibers, disposed on one side of the first nonwoven fabric layer, the air permeability of the water-permeable sheet is 3.0 μm / (Pa·s) or more, and the 60° gross value of the side of the water-permeable sheet facing the second nonwoven fabric layer is 5.0 or more.

Description

[Technical Field]

[0001] This disclosure relates to a method for manufacturing permeable sheets, plate members, formwork, and concrete products. [Background technology]

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

[0003] When hardening concrete precursors, a technique is known in which a water-permeable sheet is provided in the formwork to properly drain excess water and air bubbles from the concrete precursor. For example, Patent Document 1 discloses a water-permeable sheet for formwork in which a filtration layer (I) made of heat-fused nonwoven fabric and a breathable / water-permeable layer (II) made of nonwoven fabric are integrated. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 6-143236 [Overview of the project] [Problems that the invention aims to solve]

[0005] As described in Patent Document 1, by placing a permeable sheet on the surface of the formwork, excess water and air bubbles can be properly discharged, thereby suppressing the occurrence of shape defects such as pitting and resulting in a good concrete product. On the other hand, after the concrete precursor has hardened, the permeable sheet and formwork are usually removed (demolished) from the hardened concrete. At this time, if the permeable sheet becomes fuzzy, it becomes difficult to reuse the permeable sheet. If one tries to prevent the permeable sheet from becoming fuzzy, it may not be possible to sufficiently suppress the occurrence of shape defects such as pitting.

[0006] This disclosure is made in view of the above circumstances, and its main purpose is to provide a water-permeable sheet that suppresses the occurrence of shape defects such as pitting, while minimizing fluffing after demolding. [Means for solving the problem]

[0007] This disclosure provides a permeable sheet used in a mold for manufacturing concrete products, wherein the permeable sheet comprises 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, the permeability of the permeable sheet is 3.0 μm / (Pa·s) or more, and the 60° gross value of the side of the permeable sheet facing the second nonwoven fabric layer is 5.0 or more.

[0008] This disclosure provides a plate member used in a formwork for manufacturing concrete products, wherein the plate member comprises a substrate and the permeable sheet described above, and the substrate, the first nonwoven fabric layer and the second nonwoven fabric layer are arranged in this order in the thickness direction.

[0009] This disclosure provides a formwork for manufacturing concrete products, wherein the formwork comprises a formwork body and the permeable sheet described above, and the formwork body, the first nonwoven fabric layer and the second nonwoven fabric layer are arranged in this order in the thickness direction.

[0010] In the present disclosure, there is provided a method for manufacturing a concrete product, which includes a preparation step of preparing a formwork, and a curing step of introducing a concrete precursor into the formwork and curing the concrete precursor by a hydration reaction. The formwork has a formwork body and the above-described water-permeable sheet, and in the thickness direction, the formwork body, the first non-woven fabric layer, and the second non-woven fabric layer are arranged in this order.

Advantages of the Invention

[0011] In the present disclosure, there is an effect that a water-permeable sheet with less fluffing after demolding can be provided.

Brief Description of the Drawings

[0012] [Figure 1] It is a schematic cross-sectional view illustrating the water-permeable sheet in the present disclosure. [Figure 2] It is a schematic cross-sectional view illustrating the water-permeable sheet in the present disclosure. [Figure 3] It is a schematic cross-sectional view illustrating the manufacturing method of the water-permeable sheet in the present disclosure. [Figure 4] It is a schematic cross-sectional view illustrating the plate member in the present disclosure. [Figure 5] It is a schematic plan view illustrating the manufacturing method of the concrete product in the present disclosure. [Figure 6] It is a cross-sectional view taken along the line A-A in FIG. 5(b). [Figure 7] It is a schematic perspective view explaining the placing test using the water-permeable sheets obtained in the examples and comparative examples.

Modes for Carrying Out the Invention

[0013] The embodiments will be described below with reference to the drawings, etc. However, this disclosure can be implemented in many different ways and is not limited to the embodiments described below. In addition, the drawings may schematically represent the width, thickness, and shape of each part compared to the actual form in order to make the explanation clearer, but this is merely an example and should not be interpreted as limiting.

[0014] In this specification, when describing a manner in which one member is placed on another member, the term "above" or "below" includes, unless otherwise specified, both cases: when the other member is placed directly above or directly below the member so as to be in contact with it, and when the other member is placed above or below the member via yet another member. Similarly, in this specification, when describing a manner in which one member is placed on the surface of a member, the term "on the surface" includes, unless otherwise specified, both cases: when the other member is placed directly above or directly below the member so as to be in contact with it, and when the other member is placed above or below the member via yet another member.

[0015] The manufacturing methods for the permeable sheet, plate members, formwork, and concrete products described herein will be explained in detail below.

[0016] A. Permeable sheet Figure 1 is a schematic cross-sectional view illustrating a permeable sheet in this disclosure. As shown in Figure 1, the permeable sheet 10 has a thickness direction D T The sheet has a first nonwoven fabric layer 1 and a second nonwoven fabric layer 2 arranged along the same line. Furthermore, the present disclosure is characterized in that the permeability of the water-permeable sheet is 3.0 μm / (Pa·s) or more, and the 60° gross value of the surface S1 on the second nonwoven fabric layer 2 side of the water-permeable sheet 10 is 5.0 or more.

[0017] According to this disclosure, by having an air permeability of the permeable sheet within a predetermined range, and the 60° gross value of the side of the second nonwoven fabric layer on the permeable sheet within a predetermined range, it is possible to suppress the occurrence of shape defects such as pitting, and to obtain a permeable sheet with less fluffing after demolding. As mentioned above, permeable sheets are required to be able to properly discharge excess water and air bubbles. Also, after the concrete precursor has hardened, the permeable sheet and formwork are usually removed (demolished) from the hardened concrete. At this time, if fluffing occurs on the permeable sheet, it becomes difficult to reuse the permeable sheet. Furthermore, if fluffing occurs on the permeable sheet, it is conceivable that fibers from the permeable sheet may remain in the hardened concrete. For this reason, a permeable sheet with less fluffing after demolding is required. To prevent fluffing of the permeable sheet, for example, it is conceivable to make the surface of the permeable sheet smooth. When manufacturing permeable sheets, for example, increasing the number of heat presses can make the surface of the sheet smooth and prevent fuzzing, but it may not be possible to sufficiently suppress the occurrence of shape defects such as pitting, as the internal density of the sheet becomes excessively high, reducing its permeability.

[0018] Permeable sheets typically have resin fibers on their surface, resulting in a low 60° gloss value. In contrast, the permeable sheet in this disclosure has a high 60° gloss value. For example, as shown in Figure 3 later, when joining the first nonwoven sheet 1a and the second nonwoven sheet 2a, by placing a paper interlining X, which functions as an auxiliary film, between the second nonwoven sheet 2a and the heating roller R1, it is possible to smooth the surface of the second nonwoven sheet 2a while preventing the internal density of the first nonwoven sheet 1a and the second nonwoven sheet 2a from becoming excessively high. This increases the 60° gloss value of the side of the permeable sheet facing the second nonwoven layer without reducing the air permeability of the permeable sheet. Furthermore, by using the paper interlining X, the second resin fibers are uniformly heat-fused on the side facing the second nonwoven layer, resulting in a permeable sheet with less fluffing after demolding. As a result, the permeable sheet can be easily reused. In addition, it is possible to suppress the residue of permeable sheet fibers in the hardened concrete.

[0019] 1. Characteristics of permeable sheets (1) 60° Gross Value In this disclosure, the 60° gross value of the side of the permeable sheet facing the second nonwoven fabric layer is typically 5.0 or higher. A 60° gross value of 5.0 or higher results in a permeable sheet with less fluffing after demolding. Furthermore, "the side of the permeable sheet facing the second nonwoven fabric layer" refers to the side of the permeable sheet that is located on the opposite side from the first nonwoven fabric layer, with respect to the second nonwoven fabric layer. In addition, the side of the permeable sheet facing the second nonwoven fabric layer typically corresponds to the surface in contact with concrete.

[0020] The above 60° gross value may be 7.5 or higher, 10.0 or higher, 12.5 or higher, 25.0 or higher, 30.0 or higher, 35.0 or higher, 36.0 or higher, 38.0 or higher, or 40.0 or higher. If the above 60° gross value is too low, it may not be possible to sufficiently suppress fuzzing after demolding. On the other hand, the above 60° gross value may be, for example, 60.0 or lower, 50.0 or lower, or 45.0 or lower. Furthermore, from the viewpoint of preventing the concrete surface from becoming excessively smooth and reducing its aesthetic appeal, the above 60° gross value may be, for example, 30.0 or lower.

[0021] The 60° gloss value is measured using a gloss meter in accordance with JIS Z8741:1997. Specifically, the gloss meter is placed with the side of the permeable sheet facing upwards (the side with the second nonwoven fabric layer), and the gloss value at 60° is read. The average value of the values ​​measured at 10 arbitrary locations is used as the 60° gloss value.

[0022] (2) Air permeability The permeable sheet in this disclosure typically has an air permeability of 3.0 μm / (Pa·s) or higher. An air permeability of 3.0 μm / (Pa·s) or higher allows excess air and water vapor in the concrete to escape properly from the concrete to the formwork, effectively suppressing the occurrence of morphological defects such as pitting. The above air permeability may be 10.0 μm / (Pa·s) or higher, 15.0 μm / (Pa·s) or higher, 50 μm / (Pa·s) or higher, 100 μm / (Pa·s) or higher, 500 μm / (Pa·s) or higher, or 1000 μm / (Pa·s) or higher.

[0023] The air permeability is measured using the Ouken-type air permeability tester in accordance with the method compliant with JIS P8117:2009. Specifically, the air permeability resistance t of the water-permeable sheet is measured. K Measure the air permeability and determine the ISO air permeability P (P = 127 / t K ). In addition, the average value of five measurements will be used as the air permeability. Air permeability resistance t K The smaller the value, the higher the air permeability.

[0024] 2. Layer composition of the permeable sheet The permeable sheet in this disclosure comprises 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. The first nonwoven fabric layer and the second nonwoven fabric layer may be in contact with each other or may be disposed between other layers.

[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 contains first resin fibers. Examples of first resin fibers include polyolefin fibers and polyester fibers. Examples of polyolefin fibers include polyethylene fibers (PE fibers), polypropylene fibers (PP fibers), and ethylene-propylene copolymer fibers (PE-PP fibers). Examples of polyester fibers include polyethylene terephthalate fibers (PET fibers).

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

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

[0029] Examples of combinations of resins constituting the core and the sheath include core-sheath fibers (PET / PE) with polyethylene terephthalate as the core and polyethylene as the sheath, and core-sheath fibers (PP / PE) with polypropylene as the core and polyethylene as the sheath. In particular, the first nonwoven fabric layer preferably has core-sheath fibers (PP / PE) or core-sheath 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 it may contain two or more types of resin fibers. If the first nonwoven fabric layer contains two or more types of resin fibers, it is preferable that they are blended together. The first nonwoven fabric layer may contain core-sheath type fibers as the first resin fiber, or it may not contain core-sheath type fibers.

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

[0033] The first resin fiber is preferably not a swellable fiber (a fiber having an OH group). For example, fibers such as rayon have an OH group and therefore absorb water and swell. When they absorb water and swell, the weave of the first nonwoven fabric layer narrows, and the water permeability decreases. The first resin fiber is usually a non-swellable fiber (a fiber that does not have an OH group).

[0034] The first resin fibers are partially heat-welded to each other, forming a nonwoven fabric. Examples of nonwoven fabrics include spunbond nonwovens, meltblown nonwovens, airlaid nonwovens, flash-spun nonwovens, chemical-bonded nonwovens, needle-punched nonwovens, stitch-bonded nonwovens, thermal-bonded nonwovens, and burst-fiber nonwovens.

[0035] (ii) Surfactants The first nonwoven fabric layer may contain a surfactant. A surfactant is typically a compound having both a hydrophilic region and a hydrophobic region. Since the first resin fiber is typically hydrophobic, the hydrophobic region of the surfactant is positioned on the surface side of the first resin fiber, exposing the hydrophilic region of the surfactant. Therefore, the hydrophilicity of the first nonwoven fabric layer is improved. The surfactant can be used alone or in combination of two or more types. On the other hand, the first nonwoven fabric layer does not necessarily have to 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 they dissociate in water, and examples include alkyltrimethylammonium salts, dialkyldimethylammonium salts, and alkylbenzyldimethylammonium salts. Anionic surfactants are surfactants that become anions when they dissociate in water, and examples include sodium fatty acid salts, monoalkyl sulfates, alkylpolyoxyethylene sulfates, alkylbenzene sulfonates, and monoalkyl phosphates.

[0037] Amphoteric surfactants are surfactants that have both anionic and cationic parts in their molecule, and depending on the pH of the solution, they can be cationic, amphoteric, or anionic. Examples include alkyldimethylamine oxide and alkyl carboxybetaine. Nonionic surfactants are surfactants that have a hydrophilic part that does not ionize. Examples include polyoxyethylene alkyl ethers, fatty acid sorbitan esters, alkyl polyglucosides, fatty acid diethanolamides, and alkyl monoglyceryl ethers.

[0038] The surfactant content in the first nonwoven fabric layer is, for example, 0.1 g / m². 2 More than 300g / m 2 The following applies. Furthermore, it is preferable that the surfactant coats the first resin fiber. For example, by surface treating the first resin fiber, the surfactant adheres to the surface of the first resin fiber so as to coat it. Examples of surface treatment methods include immersion in a treatment solution in which the surfactant is diluted with distilled water, and application of a treatment solution in which the surfactant is diluted with distilled water.

[0039] (iii) First nonwoven layer If 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 absorption 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 also 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, if 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 as well, 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 also 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 / m². 2 More than 300g / m2 is as follows, 150 g / m 2 or more, 250 g / m 2 or less may also be acceptable.

[0041] (2) The second non-woven fabric layer The second non-woven fabric layer is disposed on one surface of the first non-woven fabric layer and is a layer containing second resin fibers. It has a function of retaining surplus water while retaining cement fine particles. The resin fibers contained in the second non-woven fabric layer are referred to as second resin fibers.

[0042] (i) Second resin fibers The second non-woven fabric layer contains 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 fibers may be core-sheath type fibers. Details of the core-sheath type fibers are the same as those of the core-sheath type fibers in the first resin fibers described above, so the description here is omitted. Also, the second non-woven fabric layer may contain only one type of resin fiber as the second resin fibers, or may contain two or more types of resin fibers. When the second non-woven fabric layer contains two or more types of resin fibers, it is preferable that they are blended. Also, the second non-woven fabric layer may contain core-sheath type fibers as the second resin fibers, or may not contain core-sheath type fibers. In the second non-woven fabric layer, the ratio of the core-sheath type fibers to the total amount of the second resin fibers may be 100% by mass, may be less than 100% by mass, may be 95% by mass or less, or may be 90% by mass or less. On the other hand, in the second non-woven fabric layer, the ratio of the core-sheath type fibers to the total amount of the second resin fibers may be 0% by mass, may be more than 0% by mass, may be 5% by mass or more, or may be 10% by mass or more.

[0044] The second nonwoven fabric layer may contain core-sheath type fibers, with polypropylene as the core and polyethylene as the sheath, as the second resin fiber. Alternatively, the second nonwoven fabric layer may contain polyethylene fibers as the second resin fiber. Since polyethylene fibers have a relatively low melting point, it can be difficult to produce a water-permeable sheet using them. In contrast, for example, as shown in Figure 3 described later, by arranging laminate X, a good second nonwoven fabric layer can be produced even when polyethylene fibers are used. Furthermore, in this disclosure, the surface of the second resin fiber may be polyethylene. Also, when the second resin fiber contains polyethylene, the proportion of polyethylene to all resin fibers in the second resin fiber may be, for example, 50% by mass or more, 55% by mass or more, 60% by mass or more, 70% by mass or more, 70% by mass or more, or 90% by mass or more.

[0045] (ii) Hydrophilic agents 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 fibers and the hydrophilic agent is small, the hydrophilic agent is more likely to entangle with the second resin fibers, and hydrophilicity is likely to improve. On the other hand, if the difference in solubility parameters between the two is large, it is presumed that the hydrophilic agent is less likely to entangle with the second resin fibers, and hydrophilicity is likely to decrease. 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 humectant, and animal-derived squalane extracted from shark liver oil and plant-derived squalane extracted from plants such as olives are known. An example of a squalane-based hydrophilic agent is Quinsetter SSQ-2 manufactured by Kotani Chemical Industry Co., Ltd.

[0047] Examples of polyester-based hydrophilic agents include NicePole PR-99 manufactured by Nikka Chemical Co., Ltd. Examples of olefin-based hydrophilic agents include NicePole NW-543 manufactured by Nikka Chemical Co., Ltd. Examples of nonionic silicone polymers include Quinsett PSO-7000 manufactured by Kotani Chemical Industry Co., Ltd.

[0048] The hydrophilic agent may be of the thermal crosslinking type. Thermal crosslinking hydrophilic agents polymerize through a thermal crosslinking reaction, forming a water-insoluble network molecular structure that intertwines with fibers, making them less likely to leak out and allowing for repeated use as a water-permeable sheet.

[0049] The hydrophilic agent content in the second nonwoven fabric layer is, for example, 0.1 g / m². 2 More than 100g / m 2 The following applies. Furthermore, the hydrophilic agent may coat the second resin fiber. For example, by hydrophilic treatment of the second resin fiber, the hydrophilic agent adheres to the surface of the second resin fiber, covering it. Examples of hydrophilic treatment methods include immersion in a hydrophilic treatment solution obtained by diluting the hydrophilic agent with distilled water, and application of a hydrophilic treatment solution obtained by diluting the hydrophilic agent with distilled water. Alternatively, 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 any combination of the second resin fiber and hydrophilic agent described above can be used. On the other hand, the second resin fiber and 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 also 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 / m². 2 More than 100g / m 2 The following applies: 20g / m 2 More than 80g / m 2The following are also acceptable. If the basis weight of the second nonwoven fabric layer is too small, concrete particles are more likely to penetrate, and if the basis weight of the second nonwoven fabric layer is too large, it will be difficult to absorb excess water. Furthermore, it is preferable that the basis weight of the second nonwoven fabric layer is less than that of the first nonwoven fabric layer. The difference between the basis weight of the first nonwoven fabric layer and the basis weight of the second nonwoven fabric layer is, for example, 50 g / m². 2 That is all, 100g / m 2 That's fine too.

[0052] In this disclosure, the first nonwoven fabric layer and the second nonwoven fabric layer may be in direct contact. In this case, it is preferable that the first nonwoven fabric layer and the second nonwoven fabric layer are welded at the interface between the two layers. On the other hand, 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 layers As shown in Figure 2, the water-permeable sheet 10 may have an adhesive layer 3 on the side of the first nonwoven fabric layer 1 opposite to the second nonwoven fabric layer 2. It is preferable to attach the adhesive layer 3 to the substrate or the mold body (for example, the substrate 11 or the mold body 21 in Figure 5(a)).

[0054] Examples of adhesives used in the adhesive layer include acrylic resin-based adhesives, urethane resin-based adhesives, silicone resin-based adhesives, vinyl chloride resin-based adhesives, and rubber-based 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 Figure 2, the water-permeable sheet 10 may have a release layer 4 on the side of the adhesive layer 3 opposite to the first nonwoven fabric layer 1. By providing a release layer 4, the adhesive layer 3 can be protected until it is attached to the substrate or mold body (for example, the substrate 11 or mold body 21 in Figure 5(a)). Examples of materials for the release layer 4 include paper, resin, and metal. Another example of a method for forming the adhesive layer is to coat the release layer 4 with an adhesive layer forming composition, dry it, and then laminate the side of the first nonwoven fabric layer 1 opposite to the second nonwoven fabric layer 2. Yet another example of a method for forming the adhesive layer is to attach a sheet-like adhesive layer to the side of the first nonwoven fabric layer 1 opposite to the second nonwoven fabric layer 2.

[0056] 4. Permeable sheet The thickness of the permeable sheet in this 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 permeable sheet is also used as a mold for manufacturing concrete products.

[0057] 5. Method for manufacturing a water-permeable sheet The method for manufacturing the permeable sheet in this disclosure is not particularly limited. For example, as shown in Figure 3, a method can be used in which a precursor laminate comprising 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 heating roller R1. It is preferable that the roller R2 is not heated. The heating roller R1 can be selected from, for example, a metal roller or a rubber roller. On the other hand, it is preferable that the roller R2 is a rubber roller. By using a rubber roller, the elasticity of the rubber makes it easier to press the first nonwoven fabric sheet 1a and the second nonwoven fabric sheet 2a together. By heating and pressurizing, the first nonwoven fabric sheet 1a and the second nonwoven fabric sheet 2a are densified and heat-welded to each other, and a permeable sheet having a first nonwoven fabric layer 1 and a second nonwoven fabric layer 2 is obtained. The heating temperature of the heating roller is, for example, 150°C to 190°C, and may be 160°C to 180°C.

[0058] In particular, as shown in Figure 3, by heating and pressurizing the second nonwoven fabric sheet 2a with a heating roller R1 via a laminating film X, the surface of the second nonwoven fabric layer 2 becomes smooth, and a permeable sheet having a second nonwoven fabric layer 2 with a high 60° gloss value is obtained. In particular, when the heating roller R1 is a rubber roller, the elasticity of the rubber makes it easier to press the first nonwoven fabric sheet 1a and the second nonwoven fabric sheet 2a together. On the other hand, the surface irregularities of the rubber roller are relatively large, and when heating and pressurizing are performed, these irregularities are transferred to the second nonwoven fabric layer 2a side, making it difficult to sufficiently increase the 60° gloss value of the side of the permeable sheet facing the second nonwoven fabric layer 2a. In contrast, using a smooth laminating film X (usually the surface of the laminating film X is smoother than the surface of the rubber roller) has the advantage of making it easier to increase the 60° gloss value of the side of the permeable sheet facing the second nonwoven fabric layer 2a. Examples of laminating films include resin sheets. The resin used in the resin sheet is not particularly limited, but polyethylene terephthalate (PET) is one example. The surface of the resin sheet may be smooth or it may have irregularities. Having some irregularities on the surface of the resin sheet prevents 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 its aesthetic appeal. Therefore, using a resin sheet with irregularities 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 because polyethylene fibers have a relatively low melting point. For instance, if the temperature of the heating roller is lowered, the first nonwoven fabric sheet and the second nonwoven fabric sheet may not be sufficiently bonded, and conversely, if the temperature of the heating roller is raised, the polyethylene fibers may melt and become entangled in the heating roller. In contrast, as shown in Figure 3, by heating and pressurizing the second nonwoven fabric sheet 2a with the heating roller R1 via a laminating film 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.

[0060] B. Plate member The plate member in this disclosure is a plate member used in a formwork for manufacturing concrete products, and the plate member comprises a substrate and the permeable sheet described above, and in the thickness direction, the substrate, the first nonwoven fabric layer and the second nonwoven fabric layer are in this order.

[0061] Specifically, as shown in Figure 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 In this configuration, the substrate 11, the first nonwoven fabric layer 1, and the second nonwoven fabric layer 2 are arranged in this order. Furthermore, the permeable sheet 10 shown in Figure 4 has an adhesive layer 3 on the side of the first nonwoven fabric layer 1 opposite to the second nonwoven fabric layer 2, and the adhesive layer 3 and the substrate 11 are arranged to face each other. In addition, although not specifically shown, when bonding the permeable sheet and the substrate, an adhesive layer may be provided on at least one of the permeable sheet and the substrate.

[0062] According to this disclosure, using the permeable sheet described above results in a plate member with less fuzzing after demolding. The permeable sheet is the same as described in "A. Permeable Sheet" above.

[0063] The substrates in this disclosure are not particularly limited, but examples include wood substrates and metal substrates. Examples of wood substrates include wood veneer, wood plywood, particleboard, and wood fiberboard. Examples of metal substrates include iron plates and steel plates.

[0064] C. Formwork The formwork in this disclosure is a formwork for manufacturing concrete products, and the formwork comprises a formwork body and the permeable sheet described above, and in the thickness direction, the formwork body, the first nonwoven fabric layer and the second nonwoven fabric layer are arranged in this order.

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

[0066] According to this disclosure, using the permeable sheet described above results in a formwork with less fuzzing after demolding. The permeable sheet is the same as described in "A. Permeable Sheet" above.

[0067] The formwork body in this disclosure is not particularly limited, but examples include wooden formwork and metal formwork. As shown in Figure 5(a), the formwork body 21 may be composed of a combination of multiple substrates 21. That is, the formwork 30 may be composed of a combination of multiple plate members (members having substrates 21 and permeable sheets 10).

[0068] D. Manufacturing methods for concrete products The present disclosure relates to a method for manufacturing a concrete product, comprising a preparation step of preparing a formwork, and a hardening step of placing a concrete precursor into the formwork and hardening the concrete precursor by a hydration reaction, wherein the formwork comprises a formwork body and the permeable sheet described above, and in the thickness direction, the formwork body, the first nonwoven fabric layer and the second nonwoven fabric layer are arranged in this order.

[0069] Specifically, as shown in Figure 5(a), first, a formwork 30 is prepared (preparation step). The formwork 30 has a formwork body 21 and a permeable sheet 10, and in the thickness direction, it has the formwork body 21, the first nonwoven fabric layer 1 and the second nonwoven fabric layer 2 in this order. Next, as shown in Figure 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). Also, as shown in Figure 6, excess water and air bubbles contained in the concrete precursor 51 are properly discharged through the permeable sheet 10.

[0070] According to this disclosure, by using the permeable sheet described above, a concrete product with minimal residual fibers from the permeable sheet can be obtained.

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

[0072] 2.Curing process The hardening process in this disclosure is a process of placing a concrete precursor into the above-mentioned formwork and hardening the concrete precursor by 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 water-reducing agents. Furthermore, the method of pouring the concrete precursor into the formwork is not particularly limited, and known methods can be employed.

[0074] 3. Concrete Products The method for manufacturing concrete products in this disclosure may include a demolition step after the hardening step for removing the formwork from the concrete product. The applications of the concrete products in this disclosure are not particularly limited, but include, for example, buildings, roads, dams, elevated bridges, tunnels, and port facilities.

[0075] This disclosure is not limited to the embodiments described above. The embodiments described above are illustrative, and any configuration that is substantially identical to the technical idea described in the claims of this disclosure and achieves similar effects is included within the technical scope of this disclosure. [Examples]

[0076] [Comparative Example 1] The nonwoven fabric sheet used in the first nonwoven layer comprises 50% by mass of highly hydrophilic core-sheath fibers (PP / PE) in which polypropylene (PP) is the core and polyethylene (PE) is the sheath, and which are coated with a surfactant, and 50% by mass of core-sheath fibers (PP / PE) in which polypropylene (PP) is the core and polyethylene (PE) is the sheath, and a nonwoven fabric sheet (manufactured by Tsujitomi Co., Ltd., FTPP220, basis weight 220g / m²) 2 A nonwoven fabric sheet with a PP core and a PE sheath (Thermal Bond PP / PE, manufactured by Shinwa Co., Ltd., 9540FOF, basis weight 40g / m²) was prepared for use in the second nonwoven fabric layer. 2 A material with a thickness of 0.169 mm was prepared.

[0077] These nonwoven fabric sheets were cut to a size of 5 cm x 10 cm and laminated. The resulting laminate was heated and pressurized (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] [Comparative Example 2] A water-permeable sheet was obtained in the same manner as in Comparative Example 1, except that the number of heating and pressurizing cycles using a pair of rubber rollers was changed from one to two.

[0079] [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 laminated. Furthermore, a PET separator (Nipper Co., Ltd., PET75X1-J8, arithmetic mean height Sa 1.9 μm, 60° gloss value 104.0 (measurement surface: release coating side)) was laminated as a backing 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.

[0080] [Comparative Example 3] As the nonwoven fabric sheet used for the second nonwoven fabric layer, a nonwoven fabric sheet containing PE fibers alone (manufactured by Maeda Kosen Co., Ltd., SE-2030E, basis weight 30g / m²) is used. 2 The permeable sheet was manufactured in the same manner as in Comparative Example 1, except that a material with a thickness of 0.22 mm was used. However, the molten PE fibers adhered to the laminating roll, and it was not possible to obtain a permeable sheet.

[0081] [Example 2] As the nonwoven fabric sheet used for the second nonwoven fabric layer, a nonwoven fabric sheet containing PE fibers alone (manufactured by Maeda Kosen Co., Ltd., SE-2030E, basis weight 30g / m²) is used. 2 A water-permeable sheet was obtained in the same manner as in Example 1, except that a material with a thickness of 0.22 mm was used.

[0082] [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 pressurizing by the pair of rubber rollers was changed from one to three times.

[0083] [Comparative Example 4] 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.

[0084] [Example 4] A water-permeable sheet was obtained in the same manner as in Example 2, except that a matte film (Toray Industries, Ltd., Lumirror 50X42G, arithmetic mean height Sa 1.6 μm, 60° gloss value 14.1) was used as the laminating sheet.

[0085] [Example 5] A water-permeable sheet was obtained in the same manner as in Example 2, except that a matte film (Toray Industries, Ltd., Lumirror 50X44, arithmetic mean height Sa3.7μm, 60° gloss value 47.1) was used as the laminating sheet.

[0086] [evaluation] (Gross value) The 60° gloss value was measured on the side of the second nonwoven fabric layer in the permeable sheets obtained in each example and comparative example. The 60° gloss value was measured using a gloss meter (micRo-TRI-gloss gloss meter manufactured by BYK) in accordance with the method compliant with JIS Z8741:1997. Specifically, the permeable sheet was placed with the side of the second nonwoven fabric layer facing upwards, and the gloss value at 60° was read. The average value of the values ​​measured at 10 arbitrary locations was used as the 60° gloss value. The results are shown in Table 1.

[0087] (Air permeability) The air permeability of the permeable sheets obtained in each example and comparative example was measured. The air permeability was measured using a Wangyan-type air permeability and smoothness tester (KG2S, manufactured by Asahi Seiko Co., Ltd.) in accordance with the method compliant with JIS P8117:2009. Specifically, the air permeability resistance t of the permeable sheet was measured. KThe air permeability P was measured and the ISO air permeability P was determined (P = 127 / t K Furthermore, the average value of five measurements was used as the air permeability. The results are shown in Table 1.

[0088] (Concrete pouring test) A concrete casting test was conducted using the permeable sheets obtained in each example and comparative example. Specifically, as shown in Figure 7, two board members were prepared by cutting the permeable sheet to a size of 100 mm x 50 mm and attaching them to plywood of the same size. The two board members were placed with a 20 mm gap between them so that the permeable sheets faced each other. Next, the positions of the two opposing board members were fixed with two pieces of plywood (100 mm x 50 mm) to obtain a formwork. Ready-mix concrete (Toyo Materan Co., Ltd., 60-minute quick-drying instant concrete, mix ratio: 100 (concrete) / 18.2 (water)) was poured into the obtained formwork and pressed down with a spatula. The concrete was allowed to harden at room temperature for 3 days, and then the formwork was removed from the hardened concrete.

[0089] The fluffiness of the permeable sheet on the detached formwork was evaluated according to the following criteria. The results are shown in Table 1. ○: No lint or fuzz △: 1 to 9 hairs ×: More than 10 fuzzy hairs

[0090] The appearance of the hardened concrete was observed, and the number of pitting (defective shapes) with a maximum diameter of φ between 0.5 mm and 3.0 mm was measured 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 ××: There are 10 or more pits, or pits with a maximum diameter of φ of 3.0 mm or more.

[0091] [Table 1]

[0092] As shown in Table 1, Example 1 was able to suppress fuzzing more effectively than Comparative Example 1. This is presumed to be because the 60° gloss value on the side of the second nonwoven fabric layer in the permeable sheet was increased by placing a lamination sheet during the manufacturing process. On the other hand, comparing Comparative Example 1 and Comparative Example 2, changing the number of heating and pressing cycles using a pair of rubber rollers from one to two resulted in a smoother surface on the permeable sheet and an improvement in the 60° gloss value. However, this also resulted in a decrease in air permeability due to clogging of the internal structure of the permeable sheet. As a result, while Comparative Example 2 suppressed fuzzing more effectively than Comparative Example 1, the occurrence of pitting was significant. Thus, comparing Example 1 with Comparative Examples 1 and 2, it was possible to improve the 60° gloss value without reducing air permeability by using lamination sheeting to manufacture the permeable sheet.

[0093] Examples 2-5, like Example 1, were able to suppress fluffing. Furthermore, the occurrence of pitting was also suppressed in Examples 1-5. However, Example 3 had a greater number of pitting compared to the other examples. This is presumed to be because the high lamination temperature and the increased number of densification steps using the rubber roller resulted in lower air permeability and reduced water absorption of the second nonwoven fabric layer. Comparative Example 4 also had a greater number of pitting than Example 3 due to its lower air permeability.

[0094] As described above, this disclosure provides, for example, the following inventions.

[0095] [1] A permeable sheet used in formwork for manufacturing concrete products, The permeable sheet described above comprises 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. A permeable sheet having a 60° gross value of 5.0 or more on the side facing the second nonwoven fabric layer, and an air permeability of 3.0 μm / (Pa·s) or more.

[0096] [2] The permeable sheet according to [1], wherein the 60° gross value of the side of the permeable sheet facing the second nonwoven fabric layer is 10.0 or greater.

[0097] [3] The permeable sheet according to [1], wherein the 60° gross value of the side of the permeable sheet facing the second nonwoven fabric layer is 36.0 or greater.

[0098] [4] A permeable sheet as described in any of [1] to [3] above, wherein the permeability of the permeable sheet is 15.0 μm / (Pa·s) or higher.

[0099] [5] A water-permeable sheet according to any one of [1] to [4], wherein the first nonwoven fabric layer contains a surfactant.

[0100] [6] The permeable sheet according to [5], wherein the first resin fiber is coated with the surfactant described above.

[0101] [7] The permeable sheet according to [5] or [6], wherein the surfactant is at least one of a cationic surfactant, an anionic surfactant, an amphoteric surfactant, or a nonionic surfactant.

[0102] [8] The 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 type fiber having polypropylene as the core and polyethylene as the sheath.

[0103] [9] A 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.

[0104]

[10] The above-mentioned second resin fiber contains polyethylene, The water-permeable sheet according to any one of [1] to [9], wherein the proportion of polyethylene to all resin fibers in the above-mentioned second resin fiber is 50% by mass or more.

[0105]

[11] The permeable sheet according to any one of [1] to

[10] , wherein in the second nonwoven fabric layer, the proportion of core-sheath type fibers to the total amount of the second resin fibers is less than 100% by mass.

[0106]

[12] A plate member used in formwork for manufacturing concrete products, The above-mentioned plate member comprises a substrate and a water-permeable sheet as described in any of [1] to

[11] , 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.

[0107]

[13] A formwork for manufacturing concrete products, The above formwork comprises a formwork body and a permeable sheet as described in any of [1] to

[11] , 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.

[0108]

[14] The above-mentioned formwork body is the formwork described in

[13] , which is composed of multiple substrates combined together.

[0109]

[15] The preparation process involves preparing the formwork, A hardening step is performed in which a concrete precursor is placed into the above-mentioned formwork and the concrete precursor is hardened by a hydration reaction. A method for manufacturing a concrete product having the following characteristics: The above formwork comprises a formwork body and a permeable sheet as described in any of [1] to

[11] , 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]

[0110] 1...First nonwoven fabric layer 2...Second nonwoven fabric layer 3 … Adhesive layer 4 … Release layer 10… Permeable sheet 20 … Plate member 30… Formwork

Claims

1. A permeable sheet used in formwork for manufacturing concrete products, The permeable sheet comprises 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. The permeability of the aforementioned water-permeable sheet is 3.0 μm / (Pa·s) or higher. A permeable sheet wherein the 60° gloss value of the side of the permeable sheet facing the second nonwoven fabric layer is 5.0 or greater.

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

3. The permeable sheet according to claim 1, wherein the 60° gloss value of the side of the permeable sheet facing the second nonwoven fabric layer is 36.0 or more.

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

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

6. The permeable sheet according to claim 5, wherein the first resin fiber is coated with the surfactant.

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

8. The water-permeable sheet according to claim 1, wherein the second nonwoven fabric layer contains, as the second resin fiber, a core-sheath type fiber having polypropylene as the core and polyethylene as the sheath.

9. The water-permeable sheet according to claim 1, wherein the second nonwoven fabric layer contains polyethylene fibers as the second resin fibers.

10. The aforementioned second resin fiber contains polyethylene, The water-permeable sheet according to claim 1, wherein the ratio of polyethylene to all resin fibers in the second resin fiber is 50% by mass or more.

11. The permeable sheet according to claim 1, wherein in the second nonwoven fabric layer, the proportion of core-sheath type fibers to the total amount of the second resin fibers is less than 100% by mass.

12. A plate member used in formwork for manufacturing concrete products, The plate member comprises a substrate and a water-permeable sheet according to any one of claims 1 to 11. 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.

13. A formwork for manufacturing concrete products, The formwork comprises a formwork body and a permeable sheet according to any one of claims 1 to 11. 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.

14. The formwork according to claim 13, wherein the formwork body is composed of a combination of multiple substrates.

15. The preparation process involves preparing the formwork, A hardening step is to pour a concrete precursor into the formwork and harden the concrete precursor by a hydration reaction, A method for manufacturing a concrete product having the following characteristics: The formwork comprises a formwork body and a permeable sheet according to any one of claims 1 to 11. 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.

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