Light-transmitting film with light-blocking properties in the short wavelength region, light-curable liner for pipe rehabilitation using the film and having water-blocking properties against water infiltration, and its manufacturing method

Abstract

To provide a light-transmitting film capable of selectively blocking only light rays in the short wavelength range and a light-curable liner for pipe rehabilitation using the film, which is resistant to damage, has water-blocking properties against water infiltration, and allows the film and the base material layer impregnated with a light-curable resin to be integrated after the light-curable resin has cured.SOLUTION: A light-curable liner for pipe rehabilitation has, in order from the outer circumference side, an outer foil layer 1 made of a synthetic resin film, a water-shielding sheet layer 2, a base layer 3 made of glass fiber, and an inner foil layer 4 made of a synthetic resin film. The water-shielding sheet layer 2 is made of a light-transmitting film 20 having light blocking properties for light rays in the short-wavelength range below 500 nm while having an overall light transmission of 30% or more, and a nonwoven fabric layer 24.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a light-transmitting film having a light-shielding property in the short wavelength region, and a light-curable liner for pipe rehabilitation using the film and having a water-proof property against water intrusion, and a method for manufacturing the same. [Background technology]

[0002] When pipe materials constituting a pipeline such as a sewer pipe buried underground become deteriorated, a pipe lining method has been proposed and put into practical use in which the pipeline is repaired by applying a lining to the inner surface of the deteriorated existing pipe without replacing the existing pipe with a new one. This pipe lining method uses a pipe rehabilitation liner, and the methods used to harden the resin impregnated into the base layer made of nonwoven fabric or glass fiber that makes up the pipe rehabilitation liner include a thermal hardening method using hot water or steam, and a photohardening method using ultraviolet light or visible light of 300 to 500 nm. Of these methods, the heat curing method has the advantage of being able to harden thick pipe rehabilitation liners, but on the other hand, the curing time is longer than that of the light curing method, and if water penetrates, the temperature at that point does not rise sufficiently, making the curing incomplete. Moreover, it requires large-scale heating equipment for curing, so attention is being paid to the light curing method, which does not have such problems.

[0003] Incidentally, the photocurable pipe rehabilitation liner used in the photocuring method is pulled into an existing pipe and expanded, and then irradiated with ultraviolet light or visible light of 300 to 500 nm for a predetermined period of time, thereby curing the photocurable resin impregnated into the base layer made of nonwoven fabric or glass fiber that constitutes the pipe rehabilitation liner.

[0004] When this light-curing liner for pipe rehabilitation is pulled into an existing pipe during construction, there is a concern that the light-curing resin may harden unexpectedly if exposed to sunlight containing light rays of 300 to 500 nm (sometimes referred to as "short-wavelength light rays" in this specification). To address this issue, it has been proposed to place an opaque protective film that has a high light-blocking effect against short-wavelength light, including ultraviolet rays, or a translucent protective film that can block this wavelength range on the outermost layer of a light-cured liner for pipe rehabilitation (see, for example, Patent Document 1).

[0005] However, in the case of opaque protective films, it is not possible to check the impregnation status when the photocurable resin is impregnated into the base layer made of nonwoven fabric or glass fiber.In addition, when the film is pulled into the existing pipe during construction, and after the photocurable resin impregnated into the base layer made of nonwoven fabric or glass fiber that constitutes the photocurable pipe rehabilitation liner is hardened, the illumination light irradiated from the branch pipe side does not transmit when drilling the connection part with the branch pipe, making it difficult to position and prone to incorrect drilling.

[0006] Furthermore, if a protective film is placed on the outermost layer of a photocurable liner for pipe rehabilitation, there is a risk that the protective film will be damaged by the mouth of the manhole or the steps inside the manhole during the liner insertion process.If damaged, in addition to the diffusion of the styrene odor that volatilizes from the photocurable resin impregnated into the base material layer made of nonwoven fabric or glass fiber, there is also concern that the photocurable resin will harden prematurely during the insertion process and that water will seep into the base material layer impregnated with the photocurable resin. In addition, because the protective film and the base layer impregnated with the photocurable resin do not become one after the photocurable resin hardens, there is a risk that water will penetrate between the protective film and the base layer, causing water leakage into the inside of the rehabilitated pipe. There is also a concern that the protective film will not be cut cleanly when drilling holes at the connection point with the branch pipe, making it difficult to dispose of the remaining film. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Patent No. 5620401 Summary of the Invention [Problem to be solved by the invention]

[0008] In view of the problems associated with a protective film placed on the outermost layer of a photo-curable pipe rehabilitation liner used in the above-mentioned photo-curing method, and with a photo-curable pipe rehabilitation liner using the same, the present invention aims to provide a light-transmitting film that can selectively block only light in the short wavelength range, and a photo-curable pipe rehabilitation liner that uses the film, which is resistant to damage, has water-proofing properties against water intrusion, and is integrated with a base layer impregnated with a photo-curable resin after the photo-curable resin has hardened, and a method for manufacturing the same. [Means for solving the problem]

[0009] In order to achieve the above object, the light-transmitting film of the present invention having a light-shielding property in the short wavelength region comprises: A film formed by laminating a polyamide resin layer and a polyethylene resin layer, The polyethylene resin layer contains a yellow pigment and an ultraviolet absorbing agent, It has a total light transmittance of 30% or more while blocking light in the wavelength range below 500 nm. It is characterized by:

[0010] In addition, in order to achieve the same purpose, the photocurable liner for pipe rehabilitation using the light-transmitting film of the present invention that has the property of blocking light in the short wavelength range is characterized in that it has a layer in the middle where a nonwoven fabric layer is heat-sealed to the polyethylene resin layer side of the light-transmitting film that has the property of blocking light in the short wavelength range.

[0011] In addition, the photocurable liner for pipe rehabilitation using the light-transmitting film having the light-shielding property of the present invention is provided with an outer foil layer made of a synthetic resin film, a water-shielding sheet layer, a base layer made of glass fiber, and an inner foil layer made of a synthetic resin film, in that order from the outer periphery side, The water-shielding sheet layer is a layer in which a nonwoven fabric layer is heat-sealed to the polyethylene resin layer side of the light-transmitting film having a light-shielding property in the short wavelength region according to claim 1, The nonwoven fabric layer of the water-impermeable sheet layer and the glass fiber of the base material layer are impregnated with a photocurable resin. It is characterized by:

[0012] In addition, by reducing the pressure between the outer foil layer and the inner foil layer, the outer foil layer, the water-proof sheet layer, the base material layer and the inner foil layer can be brought into close contact with each other.

[0013] In addition, the method for producing a photocurable liner for pipe rehabilitation using a light-transmitting film having a light-blocking property in the short wavelength range of the present invention is a method for producing the photocurable liner for pipe rehabilitation, which is characterized by including the following steps (1) to (4). (1) A process for preparing a laminated material having, from the outer periphery side, an outer foil layer, a waterproof sheet layer, a base material layer, and an inner foil layer in that order. (2) A step of drilling a hole from the surface of the outer foil layer through the outer foil layer and the water-resistant sheet layer, and reducing the pressure between the outer foil layer and the inner foil layer using a vacuum pad through the hole. (3) A process of impregnating the nonwoven fabric layer of the waterproof sheet layer and the glass fiber of the base material layer with a photocurable resin. (4) A process of closing and sealing the hole while the pressure between the outer foil layer and the inner foil layer is reduced, thereby bringing the outer foil layer, the waterproof sheet layer, the base layer and the inner foil layer into a tightly adhered state. Effect of the Invention

[0014] According to the present invention, a light-transmitting film having a light-blocking property for short-wavelength light rays, and a photocurable liner for pipe rehabilitation having a water-proofing property against water intrusion using said film, and a method for manufacturing the same, by using a light-transmitting film that can selectively block only light rays in the short-wavelength range, it is possible to check the impregnation status when impregnating a base layer made of nonwoven fabric or glass fiber with photocurable resin, and also, after pulling the liner into an existing pipe during construction and hardening the photocurable resin impregnated into the base layer made of nonwoven fabric or glass fiber that constitutes the photocurable liner for pipe rehabilitation, the illumination light irradiated from the branch pipe side is transmitted when drilling a connection part with the branch pipe, making it easy to position the liner. In addition, the film is resistant to damage and has water-proofing properties against water infiltration, and since the film and the base layer impregnated with the photocurable resin become one after the photocurable resin hardens, problems associated with water getting in and problems with film remaining when drilling holes for the connection to the branch pipe can be eliminated. In addition, by reducing the pressure between the outer foil layer and the inner foil layer, the outer foil layer, the waterproof sheet layer, the base material layer and the inner foil layer are brought into close contact with each other, eliminating the need for spreading work at the final stage of pulling in the light-cured liner for pipe rehabilitation during construction, allowing construction to be carried out efficiently. [Brief description of the drawings]

[0015] [Figure 1] FIG. 1 is an explanatory diagram showing one embodiment of a light-transmitting film having a light-blocking property for light rays in the short wavelength range according to the present invention, and a light-curable liner for pipe rehabilitation using the film and having a water-blocking property against water intrusion. [Diagram 2] 1 is a graph showing the transmittance for each wavelength range of light transmitted through a light transmission film having a light blocking property for light rays in the short wavelength range. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, embodiments of the light-transmitting film having a light-blocking property in the short wavelength region and a light-curable liner for pipe rehabilitation using the film and having a water-blocking property against water intrusion of the present invention will be described with reference to the drawings.

[0017] FIG. 1 shows one embodiment of the light-transmitting film of the present invention that is capable of blocking light rays in the short wavelength range, and a light-curable liner for pipe rehabilitation that uses the film and is waterproof against water infiltration. This photocurable liner for pipe rehabilitation is used in a pipe lining method in which the liner is pulled into an aged existing pipe P and, in an expanded state, irradiated with 300 to 500 nm ultraviolet or visible light for a predetermined period of time, thereby hardening the photocurable resin impregnated into the base layer made of glass fiber that constitutes the liner, thereby lining the inner surface of the aged existing pipe P and repairing the pipeline of the existing pipe P. From the outer periphery, the liner is provided, in that order, with an outer foil layer 1 made of synthetic resin film, a waterproof sheet layer 2, a base layer 3 made of glass fiber, and an inner foil layer 4 made of synthetic resin film.

[0018] The outer foil layer 1 is provided as the outermost layer to prevent damage to the photocurable pipe rehabilitation liner and to impart gas barrier properties to prevent the diffusion of organic solvents such as styrene that volatilize from the photocurable resin. For example, a film in which a polyamide resin layer and a polyethylene resin layer are laminated with an adhesive layer therebetween is used; in this embodiment, a film in which polyamide resin layers 11, 12 and polyethylene resin layers 13, 14 are laminated with an adhesive layer 15 therebetween is used. Here, either or both of the polyamide resin layer and the polyethylene resin layer each composed of two layers are used. The layer structure may be one layer or three or more layers, an adhesive layer may be provided between the same type of resin layers, or the adhesive layer may be formed from an adhesion promoter that is premixed with the resin that constitutes the polyamide resin layer and / or the polyethylene resin layer.

[0019] The water-proof sheet layer 2 is intended to impart the water-proofing properties of the photocurable liner for pipe rehabilitation and light-shielding properties against short-wavelength light including ultraviolet rays, as well as to prevent the volatilization of the photocurable resin components, and is composed of, for example, a film 20 obtained by an inflation molding method, in which a polyamide resin layer 21 and a polyethylene resin layer 22 are laminated via an adhesive layer 23, and a nonwoven fabric layer 24 heat-sealed to the polyethylene resin layer 22 side of the film 20. Here, the adhesive layer can be formed from an adhesion promoter that is preliminarily mixed with the resin that constitutes the polyamide resin layer and / or the polyethylene resin layer. The polyethylene resin layer 22 contains a yellow pigment and an ultraviolet absorbing agent, so that the film 20 has a total light transmittance of 30% or more while blocking light rays in the wavelength range of 500 nm or less. Here, "cutting light in the wavelength range of 500 nm or less" means having blocking performance in the wavelength range of 500 nm or less so that the photocurable resin used in the photocurable liner for pipe rehabilitation does not harden (does not gel) for at least two hours under an outdoor (sunlight) exposure environment; more specifically, this means that the transmittance in the wavelength range of 450 nm or less is 0.1% or less, and the transmittance in the wavelength range of 450 to 500 nm is 0.5% or less.

[0020] The polyamide resin layer 21 of the waterproof sheet layer 2 is a layer for preventing the volatilization of the photocurable resin components and blocking the diffusion of styrene odor, and does not contain any additives that would inhibit this. It is made of, for example, a polyamide 6 / 66 copolymer with a layer thickness of about 10 to 50 μm, preferably about 10 to 30 μm, and more preferably about 15 to 25 μm.

[0021] The polyethylene resin layer 22 of the water-proof sheet layer 2 is a layer for imparting light-blocking properties against light in the short wavelength range including ultraviolet rays, and contains a yellow pigment and an ultraviolet absorber as additives for this purpose.The polyethylene resin layer 22 is made of linear low-density polyethylene (LLDPE) having a layer thickness of, for example, about 80 to 200 μm, preferably about 100 to 180 μm, and more preferably about 120 to 150 μm.

[0022] The yellow pigment as an additive effectively functions to cut light in the wavelength range of 400 to 500 nm, and may be either organic or inorganic, and examples thereof include 2,4-dihydro-5-methyl-4-(phenylazo)-2-phenyl-3H-pyrazol-3-one ("SUMIPLAST YELLOW GC" (trade name) or "SUMIPLAST YELLOW R" (trade name) manufactured by Sumika Chemtex Corporation), isoindolinone, isoindoline, azomethine, anthraquinone, anthrone, xanthene (all of which are organic yellow pigments), zinc sulfide, cadmium sulfide (cadmium yellow), and bismuth vanadate (bismuth vanadium yellow) (all of which are inorganic yellow pigments). The amount of the yellow pigment added is about 0.2 to 2.0% by weight, preferably about 0.3 to 1.0% by weight, and more preferably about 0.5% by weight.

[0023] The ultraviolet absorber as an additive effectively functions to cut light in the wavelength range of 400 nm or less, and examples of such an ultraviolet absorber include zinc oxide (ZnO) (zinc oxide type 1) and 2-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole ("Tinuvin 326" (product name) manufactured by BASF Japan Ltd.). The amount of ultraviolet absorber added is about 3 to 5% by weight, preferably about 4% by weight, in the case of zinc oxide (ZnO), and about 0.5 to 2% by weight, preferably about 1% by weight, in the case of "Tinuvin 326" (product name). If necessary, an antioxidant such as tetrakis[3-(3',5'-di-t-butyl-4'-hydroxyphenyl]phenyl]propanediol may be used as an additive to prevent oxidation deterioration due to light or heat. Pentaerythritol]nyl)propionate ("Irganox 1010" (trade name) manufactured by BASF Japan Ltd.) can be added in an amount of about 0.5% by weight. It is preferable that these additives are added in the form of a master batch prior to molding so that the additives are uniformly mixed in advance.

[0024] A more specific example of the film 20 is shown below. Polyamide resin layer 21: Polyamide 6 / 66 copolymer (100% by weight) with a layer thickness of 20 μm Polyethylene resin layer 22: Linear low-density polyethylene (LLDPE) (95.5% by weight) having a layer thickness of 130 μm Yellow pigment contained in the polyethylene resin layer 22: 2,4-dihydro-5-methyl-4-(phenylazo)-2-phenyl-3H-pyrazol-3-one ("SUMIPLAST YELLOW GC" (trade name) or "SUMIPLAST YELLOW R" (trade name) manufactured by Sumika Chemtex Corporation) (0.5% by weight) Ultraviolet absorbing agent contained in the polyethylene resin layer 22: zinc oxide (ZnO) (zinc oxide type 1) (4% by weight) Table 1 and Figure 2 show the transmittance of this film 20 for each wavelength range of light (measured using an ultraviolet, visible and near infrared spectrophotometer "UH4150 manufactured by Hitachi High-Tech Corporation"), and Table 2 shows the total light transmittance and haze (haze value). (Measured using a haze meter "NDH500 manufactured by Nippon Denshoku Industries Co., Ltd." in accordance with JIS K 7361-1 / HAZE:JIS K 7136.)

[0025] [Table 1]

[0026] [Table 2]

[0027] The nonwoven fabric layer 24 of the waterproof sheet layer 2 has a basis weight of, for example, 40 g / m 2 It consists of polyester.

[0028] The base material layer 3 forms the main part of the lining (rehabilitation pipe) applied to the inner surface of the deteriorated existing pipe P, and in this embodiment, a glass fiber layer 31 and a nonwoven fabric (spunlace) layer 32 are laminated together.

[0029] The inner foil layer 4 is provided on the innermost side to prevent damage to the photocurable pipe rehabilitation liner and to impart gas barrier properties to prevent the diffusion of organic solvents such as styrene that volatilize from the photocurable resin. For example, a film in which a polyamide resin layer and a polyethylene resin layer are laminated with an adhesive layer therebetween is used. In this embodiment, a film in which polyamide resin layers 41, 42 and polyethylene resin layers 43, 44 are laminated with an adhesive layer 45 therebetween is used. Here, the layer structure of either or both of the polyamide resin layer and the polyethylene resin layer, each of which is composed of two layers, can be one layer or three or more layers, an adhesive layer can be provided between the resin layers of the same type, or the adhesive layer can be formed from an adhesion promoter that has been pre-blended into the resin that constitutes the polyamide resin layer and / or the polyethylene resin layer. The inner foil layer 4 is removed after the photocurable resin has hardened.

[0030] In the photocurable pipe rehabilitation liner, the nonwoven fabric layer 24 of the waterproof sheet layer 2 and the glass fiber layer 31 and nonwoven fabric (spunlace) layer 32 of the base material layer 3 are impregnated with a photocurable resin.

[0031] Incidentally, this light-curable pipe rehabilitation liner can be manufactured through the following steps (1) to (4). (1) A step of preparing a laminated material having, from the outer periphery side, an outer foil layer 1, a waterproof sheet layer 2, a base material layer 3, and an inner foil layer 4 in that order. (2) A process of drilling a hole from the surface of the outer foil layer 1 through the outer foil layer 1 and the water-proof sheet layer 2, and reducing the pressure between the outer foil layer 1 and the inner foil layer 4 using a vacuum pad through this hole. Here, the holes are drilled using a grindstone with a shaft, and the holes are formed at equal intervals in the longitudinal direction of the laminated material, for example, every several meters. The pressure is reduced to, for example, about 90 kpa. (3) A step of impregnating the nonwoven fabric layer 24 of the waterproof sheet layer 2 and the glass fiber layer 31 and nonwoven fabric (spunlace) layer 32 of the base material layer 3 with a photocurable resin. Here, a required amount of photocurable resin is poured into the base material layer 3 between the outer foil layer 1 and the inner foil layer 4 in advance. (4) A process of closing and sealing the hole while the pressure between the outer foil layer 1 and the inner foil layer 4 is reduced, thereby bringing the outer foil layer 1, the water-proof sheet layer 2, the base layer 3 and the inner foil layer 4 into a tightly adhered state. Here, adhesive tape such as polyester film tape is used to close the hole.

[0032] In this way, the pressure between the outer foil layer 1 and the inner foil layer 4 is reduced and the air is expelled, and the outer foil layer 1, the waterproof sheet layer 2, the base material layer 3 and the inner foil layer 4 are brought into close contact with each other, thereby eliminating the need for the stretching work to stretch out the slack in the base material layer 3 during the final stage of pulling in the light-cured liner for pipe rehabilitation during construction, and construction can be carried out efficiently.

[0033] The photocurable pipe rehabilitation liner using the light-transmitting film 20 having the ability to block light in the short wavelength range can be expected to provide the following effects. By using the light-transmitting film 20 that can selectively block only light rays in the short wavelength range, the impregnation state can be checked when the base material layer 3 made of nonwoven fabric or glass fiber is impregnated with the photocurable resin. During construction, the liner is pulled into the existing pipe P, and the light-curing resin impregnated into the base layer 3 made of nonwoven fabric and glass fiber that constitutes the light-curing liner for pipe rehabilitation is hardened. After that, when drilling the connection part with the branch pipe, the illumination light irradiated from the branch pipe side passes through, making it easy to position the liner. The outer foil layer 1 is provided on the outermost side to prevent the photocurable pipe rehabilitation liner from being damaged and to prevent the photocurable resin components from volatilizing. By impregnating the nonwoven fabric layer 24 of the waterproof sheet layer 2 and the glass fiber layer 31 and nonwoven fabric (spunlace) layer 32 of the base material layer 3 with photocurable resin, the light-transmitting film 20 and the base material layer 3 impregnated with photocurable resin become one after the photocurable resin hardens, which eliminates problems associated with water getting in and problems with film remaining when drilling holes for the connection to the branch pipe. The outer foil layer 1, waterproof sheet layer 2, base material layer 3 and inner foil layer 4 are tightly adhered to each other and do not easily slip, eliminating the need for stretching work in the final stage of pulling in the light-cured liner for pipe rehabilitation during construction, allowing construction to be carried out efficiently.

[0034] The above describes one embodiment of the light-transmitting film of the present invention that has the ability to block light in the short wavelength range, and the light-cured liner for pipe rehabilitation that uses the film and has water-proofing properties against water intrusion. However, the present invention is not limited to the above configuration, and the configuration can be changed as appropriate within the scope of the spirit of the present invention. [Industrial Applicability]

[0035] The light-transmitting film of the present invention having the ability to block light in the short wavelength range and the photocurable liner for pipe rehabilitation using the film and having water-proofing against water infiltration are capable of selectively blocking only light in the short wavelength range, are resistant to damage, and the film and the base layer impregnated with the photocurable resin are integrated after the photocurable resin has hardened. Therefore, the film can be suitably used as a photocurable liner for pipe rehabilitation used in a pipe lining method in which a lining is applied to the inner surface of an existing deteriorated pipe to repair the pipeline of the existing pipe. [Explanation of symbols]

[0036] 1 Outer foil layer 11 Polyamide resin layer 12 Polyamide resin layer 13 Polyethylene resin layer 14 Polyethylene resin layer 15 Adhesive layer 2. Water-impermeable sheet layer 20 Film (light-transmitting film with short-wavelength light blocking properties) 21 Polyamide resin layer 22 Polyethylene resin layer 23 Adhesive layer 24 Non-woven layer 3 Base material layer 31 Glass fiber layer 32 Nonwoven fabric (spunlace) layer 4 Inner foil layer 41 Polyamide resin layer 42 Polyamide resin layer 43 Polyethylene resin layer 44 Polyethylene resin layer 45 Adhesive layer

Claims

1. A film formed by laminating a polyamide resin layer and a polyethylene resin layer, The polyethylene resin layer contains a yellow pigment and an ultraviolet absorbing agent, It has a total light transmittance of 30% or more while blocking light in the wavelength range of 500 nm or less. A light-transmitting film having a light-shielding property in the short wavelength region, characterized by:

2. A light-curing type liner for pipe rehabilitation using a light-transmitting film with short wavelength light blocking properties, characterized in that it has a layer in the middle, in which a nonwoven fabric layer is heat-sealed to the polyethylene resin layer side of the light-transmitting film with short wavelength light blocking properties as described in claim 1.

3. The sheet is provided with an outer foil layer made of a synthetic resin film, a waterproof sheet layer, a base layer made of glass fiber, and an inner foil layer made of a synthetic resin film, in that order from the outer periphery side. The water-shielding sheet layer is a layer obtained by heat-sealing a nonwoven fabric layer to the polyethylene resin layer side of the light-transmitting film having a light-shielding property in the short wavelength region according to claim 1, The nonwoven fabric layer of the water-impermeable sheet layer and the glass fiber of the base material layer are impregnated with a photocurable resin. A light-curing liner for pipe rehabilitation that is waterproof against water infiltration and uses a light-transmitting film that has the ability to block light rays in the short wavelength range.

4. By reducing the pressure between the outer foil layer and the inner foil layer, the outer foil layer, the water-shielding sheet layer, the base material layer and the inner foil layer are brought into close contact with each other. A light-curing liner for pipe rehabilitation having water-proofing properties against water intrusion, using the light-transmitting film having a light-shielding property in the short wavelength region as claimed in claim 3.

5. A method for producing a photocurable liner for pipe rehabilitation as described in claim 4, which is provided with water-proofing properties against water intrusion by using a light-transmitting film with light-blocking properties in the short wavelength range, characterized in that it includes the following steps (1) to (4). (1) A process for preparing a laminated material having, from the outer periphery, an outer foil layer, a waterproof sheet layer, a base material layer, and an inner foil layer in that order. (2) A step of drilling a hole from the surface of the outer foil layer through the outer foil layer and the water-resistant sheet layer, and reducing the pressure between the outer foil layer and the inner foil layer using a vacuum pad through the hole. (3) A step of impregnating the nonwoven fabric layer of the waterproof sheet layer and the glass fibers of the base material layer with a photocurable resin. (4) A process of closing and sealing the hole while the pressure between the outer foil layer and the inner foil layer is reduced, thereby bringing the outer foil layer, the waterproof sheet layer, the base layer and the inner foil layer into a tightly adhered state.

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