Water-shielding sheet

Abstract

To provide a water-shielding sheet in which a bonding layer exhibits a good bonding strength even when manufactured using a molten resin.SOLUTION: A water-shielding sheet 1 comprises: a base material layer 10 made of a thermoplastic resin and having a water-shielding property; and an adhesive layer 20 having a structure that allows a fluid adhesive to pass therethrough, and provided on one side of the base material layer 10. A portion of the thermoplastic resin penetrates into the adhesive layer 20, and in the adhesive layer 20, an exposed thickness that is a thickness of a portion into which the thermoplastic resin is not penetrated is 100 μm or more.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a waterproof sheet. [Background technology]

[0002] Block mats, which are easy to construct and transport, are widely used to protect river banks and slopes of reclaimed land. Generally, block mats are made up of a number of concrete blocks attached to a flexible support sheet. Block mats can be quickly and easily installed by laying them on a leveled slope using a crane or other equipment and fixing them in place with anchor pins or other equipment.

[0003] In recent years, damage caused by heavy rains has been increasing nationwide due to the effects of global warming. When heavy rains cause rivers to flood, the sediment on the riverbanks is carried away, causing the riverbanks to collapse and flood. In order to prevent such collapses and floods caused by rising water levels, there is an increasing need for water-impermeable and waterproof block mats. Patent Document 1 describes a resin sheet for block mats that can be used for such purposes. This sheet has a base layer with water-proofing properties and a bonding layer provided on one side of the base layer to increase the bonding strength with the support sheet of the block mat, and exhibits water-proofing properties as a whole. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2020-122329 A Summary of the Invention [Problem to be solved by the invention]

[0005] As will be described in more detail below, the inventors have newly discovered a problem that arises when making such a water-proof sheet using a specific method, more specifically, a method of forming a base layer using a molten resin, and have completed the present invention.

[0006] An object of the present invention is to provide a waterproof sheet in which the bonding layer exhibits good bonding strength even when produced using a molten resin. [Means for solving the problem]

[0007] The present invention is a waterproof sheet comprising a base layer made of a thermoplastic resin and having water-proofing properties, and an adhesive layer provided on one side of the base layer and having a structure that allows a fluid adhesive to pass through. In this waterproof sheet, a portion of the thermoplastic resin penetrates into the bonding layer, and the exposed thickness of the bonding layer, which is the thickness of the portion not penetrated by the thermoplastic resin, is 100 μm or more. Effect of the Invention

[0008] According to the present invention, a waterproof sheet can be provided in which the bonding layer exhibits good bonding strength even when produced using a molten resin. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic cross-sectional view of a waterproof sheet according to one embodiment of the present invention. [Diagram 2] FIG. 13 is a diagram for explaining the definition of an exposed thickness of a bonding layer. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] An embodiment of the present invention will be described with reference to FIGS. 1 is a cross-sectional view showing a schematic diagram of a waterproof sheet 1 according to the present embodiment. The waterproof sheet 1 includes a base layer 10 having waterproof properties and a bonding layer 20 provided on one surface of the base layer 10.

[0011] The material of the base layer 10 may be a thermoplastic resin, and examples of the material include low-density polyethylene (hereinafter, "LDPE"), linear low-density polyethylene (hereinafter, "LLDPE"), ethylene-vinyl acetate copolymer (hereinafter, "EVA"), polyvinyl chloride (hereinafter, "PVC"), etc. The base layer 10 may be a single layer, or may be composed of multiple layers. The base layer 10 may be formed of one type of resin material, or may be formed by mixing two or more types of resin materials. For example, mixing EVA with polyethylene provides the following advantages: improved handling during construction, resistance to tearing on uneven ground when laid, and resistance to stretching of the resin when lifted up in a state where it is joined to a block mat. Furthermore, the substrate layer 10 may also contain auxiliary components such as a weather resistance stabilizer. Examples of the weather resistance stabilizer include hindered amine light stabilizers (HALS).

[0012] The bonding layer 20 can be made of a known nonwoven fabric, for example, a nonwoven fabric made by intertwining synthetic fibers into a sheet shape. In addition, a nonwoven fabric made of natural fibers can also be used. Paper is also included in the nonwoven fabric of the present invention.

[0013] The waterproof sheet 1 exhibits waterproof performance as a whole, that is, the performance of suppressing the permeation of water from one side to the other side in the thickness direction, due to the waterproof property of the base layer 10. Therefore, by bonding it to a support sheet described later in the process of manufacturing a block mat, a waterproof block mat can be manufactured. As another method of use, waterproof performance can be imparted to a block mat by joining the waterproof sheet 1 to the support sheet of an already completed block mat.

[0014] A sheet having the same structure as the waterproof sheet 1 can be produced by bonding a resin film that will form the base layer 10 and a nonwoven fabric that will form the bonding layer 20 together with an adhesive, or by co-extruding a molten resin material that will form the base layer 10 and a nonwoven fabric that will form the bonding layer 20 together. Here, the inventors have found a new problem that occurs when the latter method is used.

[0015] Specifically, it was found that if an excessive amount of the molten resin penetrates into the nonwoven fabric that becomes the bonding layer, the function of the bonding layer 20 is reduced. When a waterproof sheet is applied to a block mat, the adhesive supplied from the block side penetrates the support sheet and penetrates into the bonding layer. As a result, the bonding layer and the block are firmly bonded by the adhesive located in the support sheet and on both sides in the thickness direction. However, if a large amount of molten resin that will become the base layer penetrates into the nonwoven fabric during the manufacture of the waterproof sheet, the space in the joining layer into which the adhesive that is supplied when the waterproof sheet is used is reduced. As a result, it was found that the adhesive cannot sufficiently penetrate into the joining layer, and the bonding to the joining object such as a block is reduced. It was also found that this phenomenon is more likely to occur as the temperature of the molten resin that will become the base layer 10 during manufacture increases.

[0016] After extensive investigation into this phenomenon, the inventors discovered that the bonding layer can perform adequately by setting the exposed thickness, which is the thickness of the portion of the bonding layer that has not been penetrated by the molten resin that forms the base material layer, to a predetermined value or greater. Details will be explained using experimental examples, but specifically, it has been discovered that by making the exposed thickness 100 μm or more, the base material layer 10, which exhibits water-blocking properties, can be firmly bonded to the object to be bonded using a liquid adhesive.

[0017] The exposed thickness can be increased by a number of methods described below. By using these methods alone or in appropriate combination, the exposed thickness of the bonding layer 20 can be made 100 μm or more. Use thick non-woven fabric. -Weight (density (g / m 2 )) high-performance nonwoven fabric is used. The material of the base layer 10 is a resin with high melt viscosity.

[0018] A method for measuring the exposed thickness in the present invention will be described. A cross-sectional photograph is obtained of a completed waterproof sheet, including both a portion where there is no or little bonding layer 20 on the base material layer 10, such as the peripheral portion 2 shown in Fig. 1, and a portion where the bonding layer 20 is disposed on the base material layer 10. In the obtained cross-sectional photograph, as shown in Fig. 2, the upper surface 10a of the base material layer 10 in the portion where there is no bonding layer 20 thereon is set as a reference, and the distance D1 between the upper surface 10a and the upper surface 20a of the bonding layer 20 in the thickness direction of the waterproof sheet is defined as the exposed thickness of the bonding layer 20. In the case where there is no portion on the base material layer 10 where the bonding layer 20 is not present, if the nonwoven fabric is needle-punched, the portion that has become thin due to processing may be the upper surface 10a. In the case where the nonwoven fabric is not needle-punched, the highest position of the portion where the resin has penetrated may be the upper surface 10a. When taking a cross-sectional photograph, it is preferable to leave the cross-section for about 5 minutes after forming the cross-section to stabilize the bonding layer 20. The exposed thickness can be calculated by counting the number of pixels using the image, or the like.

[0019] The waterproof sheet according to the present invention will be further described using experimental examples. The technical scope of the present invention is not limited in any way solely on the basis of the specific contents of the experimental examples. (Experimental Example 1) The bonding layer was a nonwoven fabric (Ekure 3501A manufactured by Toyobo Co., Ltd.) made of embossed polyester long fibers produced by the spunbond method. The thickness and basis weight of the nonwoven fabric are shown in Table 1 below. The thickness was measured using a Mitutoyo Count Outside Micrometer M800, and the basis weight was measured in accordance with JIS L-1913. EVA was selected as the material for the substrate layer, and in a molten state, it was extruded onto the nonwoven fabric at approximately 190° C. to form a substrate layer having a thickness of 1.1 mm on one side of the nonwoven fabric.

[0020] As described above, a waterproof sheet according to Experimental Example 1 was produced.

[0021] (Experimental Example 2) The bonding layer was a nonwoven fabric (Ekure 3601B, manufactured by Toyobo Co., Ltd.) made of embossed polyester long fibers produced by the spunbond method. The thickness and basis weight of the nonwoven fabric are shown in Table 1 below. The waterproof sheet of Experimental Example 2 was produced in the same manner as Experimental Example 1 except for the above.

[0022] (Experimental Example 3) The bonding layer was a nonwoven fabric (Ekure 3501AD, manufactured by Toyobo Co., Ltd.) made of embossed polyester long fibers produced by the spunbond method. The thickness and basis weight of the nonwoven fabric are shown in Table 1 below. The waterproof sheet of Experimental Example 3 was produced in the same manner as Experimental Example 1 except for the above.

[0023] (Experimental Example 4) The bonding layer was a nonwoven fabric (Ekure 3501B, manufactured by Toyobo Co., Ltd.) made of embossed polyester long fibers produced by the spunbond method. The thickness and basis weight of the nonwoven fabric are shown in Table 1 below. The waterproof sheet of Experimental Example 4 was produced in the same manner as Experimental Example 1 except for the above.

[0024] (Experimental Example 5) A wet spunlace nonwoven fabric (NR92040 manufactured by Sanwa Paper Co., Ltd.) made of rayon and pulp fibers was used as the bonding layer. The thickness and basis weight of the nonwoven fabric are shown in Table 1 below. The waterproof sheet of Experimental Example 5 was produced in the same manner as Experimental Example 1 except for the above.

[0025] The waterproof sheets of each example were evaluated for the following two items. (Exposed thickness of bonding layer) Measurements were made according to the above definition using cross-sectional photographs taken with an optical microscope (Hirox KH-8700). The height of the upper surface of the bonding layer was calculated by the arithmetic mean value of the heights at five randomly selected points. (Bonding strength with objects to be joined) A PET substrate with a silicone coating of 75 μm in thickness was prepared. 5.6 to 6.3 g of epoxy-amine adhesive was applied and spread on the silicone-coated surface. Next, a sheet using Taslan textured yarn described in JP 2011-26947 A (hereinafter, "textured yarn sheet"), which was intended as a support sheet for the block mat, was superimposed on the adhesive layer. Furthermore, the waterproof sheets according to each example were superimposed with the bonding layer facing the textured yarn sheet, and left to stand for 24 hours or more under a pressure of 2 kgf or more and an environment of 5°C or higher to harden the adhesive. This resulted in a waterproof sheet assembly according to each example, in which the PET substrate and the waterproof sheet were bonded via the adhesive that had permeated the textured yarn sheet. A 10mm wide test piece was cut out from each waterproof sheet joint, and a 180° peel test was performed using a universal testing machine (A&D Corporation, Tensilon RTG-1225) with the PET substrate and waterproof sheet clamped together, and the maximum peel strength was recorded. The results are shown in Table 1.

[0026] [Table 1]

[0027] In Experimental Examples 1 to 3, in which the exposed thickness of the bonding layer was 100 μm or more, the peel strength was 10 N / cm or more. This suggests that when applied to block mats, peeling of the waterproof sheet due to its own weight can be effectively prevented even if the completed block mat is lifted by gripping the block with heavy machinery.

[0028] On the other hand, in Experimental Examples 4 and 5, where the exposed thickness of the bonding layer was less than 100 μm, the peel strength was insufficient at less than 10 N / cm. From the results of Experimental Examples 1 to 5, it was inferred that it is not easy to estimate the exposed thickness in the completed waterproof sheet from the basis weight and thickness of the nonwoven fabric used in the bonding layer. 2 It was shown that by using a nonwoven fabric having a thickness of 160 μm or more, it is almost certain that a bonding layer with an exposed thickness of 100 μm or more can be achieved.

[0029] The waterproof sheet according to the present embodiment, which was constructed based on the above experiments, includes a base layer and a bonding layer, and has a sufficient exposed thickness at the bonding layer, which allows the base layer to exhibit a sufficient waterproof function while being bonded to an object to which waterproofing is to be imparted with sufficient bonding strength using a fluid adhesive.

[0030] The above describes the embodiments and experimental examples of the present invention, but the technical scope of the present invention is not limited to the contents of the above embodiments, etc., and various modifications and deletions can be made to each component without departing from the spirit of the present invention.

[0031] The configuration of the bonding layer is not limited to the above-mentioned nonwoven fabric, but may be any material, such as knitted fabric or porous material, that has a structure through which a fluid adhesive can permeate in the thickness direction.

[0032] The scope of application of the waterproof sheet of the present invention is not limited to the block mat described above, but can be attached using a fluid adhesive to various objects where waterproofing should be imparted or enhanced, such as waste disposal sites, offshore structures, and building rooftops and terraces, and sufficient bonding strength can be ensured.

[0033] The waterproof sheet of the present invention, in addition to exhibiting water blocking properties, can also inhibit the penetration of substances other than water, such as oil, soil, etc. Furthermore, since it also exhibits a certain degree of inhibition effect on the penetration of gas, sound (audible and inaudible ranges), heat, light (visible and invisible ranges), etc., it can also be used in applications that impart or enhance the shielding properties of these substances to objects. [Explanation of symbols]

[0034] 1. Waterproof sheet 10 Base material layer 20 Bonding layer

Claims

1. A base layer made of a thermoplastic resin and having water impermeability; A bonding layer having a structure through which a fluid adhesive can pass and provided on one surface of the base material layer; Equipped with A part of the thermoplastic resin penetrates into the bonding layer, In the bonding layer, an exposed thickness, which is a thickness of a portion into which the thermoplastic resin has not penetrated, is 100 μm or more. Waterproof sheet.

2. The bonding layer is made of a nonwoven fabric. The waterproof sheet according to claim 1.

3. The base material layer contains an ethylene-vinyl acetate copolymer as the thermoplastic resin. The waterproof sheet according to claim 1.

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