JP2008012915A - Manufacturing method of waterproof sheet for tunnel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a waterproof sheet for a tunnel which solidly and integrally adheres to the a tunnel structure of concrete generates no gaps between the waterproof sheet and the concrete even after passing a long period of time, does not generate breakage or others, and prevents leaching water from the ground or others from leaking into a tunnel. <P>SOLUTION: The manufacturing method of the waterproof sheet for a tunnel having a silica-containing surface layer containing the silica in the concentration of 30 to 200 mg/cm<SP>3</SP>in the depth of 5 to 30 μm from the sheet surface comprises applying a silica dispersing liquid (a<SB>1</SB>) constituted by dispersing a silica containing 90 wt.% or more of SiO<SB>2</SB>and having BET specific surface area of 80 m<SP>2</SP>/g or more in an organic solvent dissolving a synthetic resin constituting the front face layer of the synthetic resin made base sheet or a silica dispersing liquid (a<SB>2</SB>) constituted by additionally adding the thickener compatible to the synthetic resin of the front face layer of the base sheet into the silica dispersing liquid (a<SB>1</SB>) on the surface of the synthetic resin made base sheet, and heating and drying the same. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a waterproof sheet for tunnel made of synthetic resin. More specifically, the present invention is installed between a natural ground or ground and a concrete tunnel structure in tunnel construction such as a mountain tunnel or an urban underground tunnel, and exudes from the natural ground or ground. The present invention relates to a method for manufacturing a waterproof sheet for a tunnel for preventing water from leaking into the tunnel.

In tunnel construction such as mountain tunnels and underground tunnels in urban areas, the mountain tunnel method (NATM method) and shield method have been conventionally used, and in either case, leakage of water from the ground and ground to the tunnel is prevented. Waterproof sheets have been used for this purpose.
As the waterproof sheet, a waterproof sheet in which a fluororesin crosslinked foam is laminated on at least one surface of a thermoplastic resin or vulcanized synthetic resin sheet (see Patent Document 1), a propylene homopolymer block or an ethylene content of 5% by weight. A waterproof sheet (see Patent Document 2) comprising a block copolymer having the following propylene-ethylene random copolymer block A and an ethylene-propylene random copolymer block B having a propylene content of 10% by weight or more; A waterproof sheet mainly composed of a mixture of two or more different ethylene-vinyl acetate copolymers (see Patent Document 3) is known.

  However, since all of the conventional waterproof sheets described in Patent Documents 1 to 3 are inferior in adhesiveness and adhesion to a concrete structure built inside the tunnel, time elapses after the installation of the waterproof sheet. Then, the water that oozes from the ground and ground flows through the gap between the waterproof sheet and the concrete structure and flows in from the poorly joined or torn part of the waterproof sheet and from the cracks in the concrete structure into the concrete structure. It is easy to cause the problem of water leakage.

  In order to solve the above-described problems in the conventional waterproof sheet and obtain a waterproof sheet having excellent adhesion to concrete, the present inventors have prepared an ethylene-vinyl acetate copolymer having a vinyl acetate content of 80 to 99% by mass. An ethylene-vinyl acetate copolymer containing (A) and an ethylene-vinyl acetate copolymer (B) having a vinyl acetate content of 50 to 70 mass% in a mass ratio of (A) / (B) = 0.2-5 A water-impervious sheet for civil engineering work having a surface made of a combined composition was developed and applied (see Patent Document 4).

  The water shielding sheet of Patent Document 4 developed by the present inventors is superior in adhesiveness to a hydraulic material such as concrete as compared with conventional waterproof sheets as described in Patent Documents 1 to 3, It is difficult to peel off from hard materials and has an excellent water shielding effect. The present inventors have further studied based on the water shielding sheet of Patent Document 4. In order to more effectively prevent the water that has exuded from the ground and the ground from entering the concrete tunnel structure, it is necessary to further improve the adhesion characteristics of the waterproof sheet to the concrete structure. It has been found.

JP 7-329228 A Japanese Patent Laid-Open No. 9-52330 JP 2001-115791 A JP 2002-294015 A

  The object of the present invention is to firmly bond and integrate with a concrete tunnel structure, and even if a long time elapses after construction, there is no gap between the waterproof sheet and the concrete structure, thereby preventing the natural ground and the ground. It is an object of the present invention to provide a method for manufacturing a waterproof sheet for a tunnel that can completely prevent the seepage of water that has oozed out from the inside of a concrete structure.

  The present inventors have made various studies in order to achieve the above object. As a result, instead of applying an aqueous dispersion of silica to the surface of the base sheet made of synthetic resin, silica having a specific silicon dioxide content and a specific specific surface area is dissolved in the surface layer portion of the base sheet. After applying a dispersion dispersed in an organic solvent having a silica, or after applying a silica dispersion further containing a thickener having an affinity for the surface layer portion of the substrate sheet in the organic solvent dispersion of silica. When the silica-containing surface layer containing the silica at a specific concentration is formed on the surface layer portion of the base sheet from the surface to a specific depth by heating and drying, it has a high adhesive strength to concrete, and 15 N / It has been found that a waterproof sheet for tunnels having a high mortar adhesion force of cm or more can be obtained smoothly.

  In addition, the present inventors, in that case, ethylene- having a content ratio of structural units derived from vinyl acetate in a specific range as a synthetic resin for forming a surface layer portion of a base sheet made of a synthetic resin or a synthetic resin for a surface layer. When a vinyl acetate copolymer is selected and used, and when an ethylene-vinyl acetate copolymer is used as a synthetic resin constituting a portion under the surface layer portion or a synthetic resin for forming a sheet body, an organic solvent of silica is further used. When a specific ethylene-vinyl acetate copolymer is selected and used as a synthetic resin to form a thickener contained in the dispersion, it has a high tensile breaking strength with the above-mentioned high adhesion to concrete, When used for waterproofing, the waterproof sheet for tunnels can waterproof the tunnel well over a long period of time without causing damage to the sheet or leakage of water. Found that the resulting, and have completed the present invention based on their various findings.

That is, the present invention
(1) Synthesis on the surface of a base sheet made of a synthetic resin, which forms a surface layer portion of the base sheet with silica having a silicon dioxide content of 90% by mass or more and a BET specific surface area of 80 m ² / g or more Increase in affinity with silica dispersion (a ₁ ) dispersed in an organic solvent having a dissolving action on the resin, or synthetic resin constituting the surface layer portion of the substrate sheet in the silica dispersion (a ₁ ) Silica containing 30 to 200 mg / cm ³ of the silica at a depth of 5 to 30 μm from the surface of the base sheet after applying a silica dispersion (a ₂ ) further containing a sticking agent and then drying by heating. It is a manufacturing method of the waterproof sheet for tunnels made from a synthetic resin which has a silica containing surface layer characterized by forming a containing surface layer.

And this invention,
(2) The method for producing a waterproof sheet for a tunnel according to (1), wherein the thickener having an affinity for the synthetic resin constituting the surface layer portion of the base sheet and the base sheet is an ethylene-vinyl acetate copolymer;
(3) The synthetic resin constituting the surface layer portion of the base material sheet and the synthetic resin constituting the surface layer portion of the base material sheet have an affinity for the structural unit derived from vinyl acetate of 30% by mass or more. (1) or (2) a method for producing a waterproof sheet for tunnels comprising an ethylene-vinyl acetate copolymer; and
(4) The method for producing a tunnel waterproof sheet according to any one of (1) to (3), wherein the tunnel waterproof sheet having a mortar adhesive force of 15 N / cm or more is produced;
It is.

Furthermore, the present invention provides:
(5) As a base sheet made of a synthetic resin, the surface layer portion is made of an ethylene-vinyl acetate copolymer having a vinyl acetate unit content of 30% by mass or more, and the portion under the surface layer portion is ethylene-vinyl acetate copolymer Using a base material sheet made of coalescence, silica having a silicon dioxide content of 90 mass% or more and a BET specific surface area of 80 m ² / g or more on the surface of the base material sheet is 1 to the mass of the dispersion. The silica dispersion (a ₁ ) contained at a concentration of ˜20% by mass is applied at a coating amount of ² to 50 g / m ² , or the content of vinyl acetate units in the silica dispersion (a ₁ ) is 30 After applying a silica dispersion (a ₂ ) further containing ₂ % by weight or more of an ethylene-vinyl acetate copolymer as a thickener at a coating amount of ² to 50 g / m ² , drying by heating, a base sheet The silica is added to the surface layer of 3 To 200 mg / cm ³ silica-containing surface layer containing at is formed over a depth of 5~30μm from the surface of the substrate sheet, wherein (1) a to (4) any of the manufacturing method of a waterproof sheet for a tunnel.

By the manufacturing method of the present invention, it is firmly bonded and integrated with a concrete tunnel structure, and even if a long time elapses after construction, there is no gap between the waterproof sheet and the concrete structure, thereby A waterproof sheet for a tunnel that can completely block water that has oozed from the ground and prevent the oozed water from entering the inside of the concrete structure can be manufactured smoothly.
Furthermore, since the waterproof sheet for tunnels obtained by the production method of the present invention has a large tensile strength at break, even if the waterproof sheet is stressed during or after the installation of the waterproof sheet, damage or other problems may occur. It does not occur and its excellent waterproof effect can be maintained for a long time.

The present invention is described in detail below.
In the present invention, the surface layer portion of the base sheet is composed of silica having a silicon dioxide content of 90% by mass or more and a BET specific surface area of 80 m ² / g or more on the surface of the base sheet made of synthetic resin. Silica dispersion (a ₁ ) dispersed in an organic solvent having a dissolving action on the synthetic resin, or an affinity with the synthetic resin constituting the surface layer portion of the substrate sheet in the silica dispersion (a ₁ ) After applying a silica dispersion (a ₂ ) further containing a thickener, it is dried by heating and contains the silica at a depth of 5 to 30 μm from the surface of the base sheet at 30 to 200 mg / cm ³ . A method for producing a waterproof sheet for tunnel made of synthetic resin having a silica-containing surface layer, wherein a silica-containing surface layer is formed.
By this production method of the present invention, a tunnel waterproof sheet excellent in adhesive strength with concrete can be produced smoothly with good processability.

In the production method of the present invention, in order to obtain a tunnel waterproof sheet having high adhesive strength with concrete forming a tunnel, the content of silicon dioxide as silica for forming a silica-containing surface layer on the tunnel waterproof sheet Is used and silica having a BET specific surface area of 80 m ² / g or more is used.

In general, silica contains subcomponents such as aluminum oxide, iron oxide, and graphite in addition to silicon dioxide, which is the main component. These subcomponents have the ability to react and bond with cement. Therefore, if these subcomponents are contained in silica in an amount of 10% by mass or more and the silicon dioxide content in silica is less than 90% by mass, the adhesive strength of the tunnel waterproof sheet to concrete or mortar is sufficient. In particular, a tunnel waterproof sheet having a “mortar adhesive strength” of 15 N / cm or more cannot be obtained.
For example, a silicon-based mineral containing graphite called silica black or black silica is laid under the floor of a house using its deodorizing, antibacterial, and dehumidifying actions, but the silicon dioxide content is about 80% by mass. Yes, even if a silica-containing surface layer is formed using such a material, a waterproof sheet for tunnels having a mortar adhesive strength of 15 N / cm or more cannot be obtained.
In the present invention, a silica having a higher purity is more preferably used as a silica for forming a silica-containing surface layer in a tunnel waterproof sheet (hereinafter sometimes simply referred to as “waterproof sheet”). Silica having an amount of 92% by mass or more, particularly 95% by mass or more is preferably used.

Furthermore, in the present invention, it is necessary to use silica having a BET specific surface area of 80 m ² / g or more as silica having a silicon dioxide content of 90 mass% or more, and a BET specific surface area of 90 m ² / g or more. A thing of 100 m < ² > / g or more is used more preferably. If the BET specific surface area of silica is too small outside the above range, the contact area between silica and concrete and reaction points will be reduced when a concrete raw material is applied to the silica-containing surface layer of the waterproof sheet. It can no longer be obtained. The BET specific surface area is known to be inversely proportional to the primary particle diameter of the particles, and the silica used in the present invention having a BET specific surface area of 80 m ² / g or more generally has a primary particle diameter of 40 nm or less.

Examples of the method for producing silica include a wet method, a dry method, an electric arc method, etc. In the present invention, the content of silicon dioxide produced by a wet method from the viewpoint of the balance between the cohesiveness of particles and moisture adsorption. Is preferably 90% by mass or more and a BET specific surface area of 80 m ² / g or more. Furthermore, wet methods include precipitation and gel methods, but the number of silanol groups that react with concrete to form tobermorite is greater in the silica obtained by the precipitation method than in the silica obtained by the gel method. Therefore, silica obtained by a precipitation method and having a silicon dioxide content of 90% by mass or more and a BET specific surface area of 80 m ² / g or more is preferably used. The number of silanol groups is generally about 8 / nm ² for silica obtained by the precipitation method and about 5 / nm ^{2 for} silica by the gel method.

In the production method of the present invention, silica having a silicon dioxide content of 90% by mass or more and a BET specific surface area of 80 m ² / g or more [hereinafter, “silica (SiO ₂ ≧≧ 90%, BET ≧ 80 m ² / g) ”or simply“ silica ”] is dispersed in an organic solvent having a dissolving action on the synthetic resin constituting the surface portion of the base sheet. (a ₁₎ or coating, or the silica dispersion (a ₁₎ silica dispersion further contain a thickener and synthetic resin constituting the surface layer portion of the substrate sheet is compatible in (a ₂ ), And then dried by heating to form a silica-containing surface layer on the substrate sheet.

As a base material sheet made of a synthetic resin to which the silica dispersion (a ₁ ) or the silica dispersion (a ₂ ) is applied, a synthetic resin in which a surface layer portion to be a silica-containing surface layer is composed of at least an ethylene-vinyl acetate copolymer A sheet made from the resin is preferably used. Among them, as a base material sheet, the surface layer portion is composed of an ethylene-vinyl acetate copolymer having a content ratio of structural units derived from vinyl acetate (hereinafter referred to as “vinyl acetate units”) of 30% by mass or more. A resin sheet is more preferably used, and a synthetic resin sheet made of an ethylene-vinyl acetate copolymer having a surface layer portion containing 32% by mass or more of vinyl acetate units is more preferably used. A synthetic resin sheet made of an ethylene-vinyl acetate copolymer having a content ratio of 32 to 50% by mass is more preferably used.
An ethylene-vinyl acetate copolymer, particularly an ethylene-vinyl acetate copolymer containing a vinyl acetate unit in a proportion of 30% by mass or more is excellent in adhesion to concrete. Moreover, an ethylene-vinyl acetate copolymer having a vinyl acetate unit content of 30% by mass or more, more preferably 32% by mass or more, and particularly 32 to 50% by mass is excellent in solubility in an organic solvent.

A synthetic resin sheet made of an ethylene-vinyl acetate copolymer having a vinyl acetate unit content of 30% by mass or more on the surface layer portion is used as the base sheet, and silica (SiO ₂ ≧ _{90%, BET ≧ 80m 2 /} g) silica dispersion obtained by dispersing (a ₁₎ or the dispersion (a ₁₎ to a further coating to heating and drying the silica dispersion (a ₂₎ the addition of a thickener In this case, the surface layer portion of the base sheet is well swollen and / or dissolved by the silica dispersion (a ₁ ) or the organic solvent used in the silica dispersion (a ₂ ), and the swelling and / or dissolution thereof. Since the silica is uniformly dispersed and adhered to the surface layer portion, heat drying is performed. Therefore, silica (SiO ₂ ≧ 90%, BET ≧ 80 m ₂₎ extends from the outermost surface to the inside of the surface layer portion made of an ethylene-vinyl acetate copolymer. / g) is evenly dispersed The silica is a silica-containing surface layer which is firmly held is formed on the substrate sheet together in a resin forming the surface layer portion.
In particular, the use thickener further added silica dispersion (a _2), to the polymer deposited also adhere used as a thickening agent in the surface layer of the base sheet after heat drying, silica (SiO ₂ ≧ 90%, BET ≧ 80 m ₂ / g) is more firmly held in the silica-containing surface layer.
When the surface layer portion of the base sheet is formed from an ethylene-vinyl acetate copolymer having a vinyl acetate unit content of less than 30% by mass, the surface layer portion of the base sheet is less likely to be swollen by an organic solvent. It is difficult to form a silica-containing surface layer in which silica (SiO ₂ ≧ 90%, BET ≧ 80 m ² / g) is uniformly dispersed and firmly held from the outermost surface to a predetermined depth.

In the base sheet made of synthetic resin, the type of synthetic resin that forms a portion below the surface layer portion that becomes the silica-containing surface layer is not particularly limited, and ethylene-vinyl acetate copolymer, polyvinyl chloride, ECB (ethylene. Copolymer / bitumen), thermoplastic polyurethane, olefin polymer, and other thermoplastic synthetic resins.
Among them, in the present invention, the base sheet is preferably a synthetic resin sheet in which the surface layer portion is composed of the above-described ethylene-vinyl acetate copolymer, and the portion below the surface layer portion is also composed of the ethylene-vinyl acetate copolymer. Used.
The ethylene-vinyl acetate copolymer has high tensile strength, tear strength, etc., has a high elongation rate, is easy to be molded by extrusion molding, calender roll, etc., and has excellent chemical resistance, as well as vinyl acetate. The physical properties of the polymer can be adjusted by changing the copolymerization ratio of the unit. Therefore, when trying to produce a waterproof sheet having a tensile strength at break of 10 MPa or more and a tensile elongation at break of 300% or more by the production method of the present invention, not only the surface layer portion of the base sheet but also the surface layer portion. It is preferable to use a synthetic resin sheet made of an ethylene-vinyl acetate copolymer for the lower part.

  As a base material sheet, the surface layer portion of the base material sheet is made of an ethylene-vinyl acetate copolymer having a vinyl acetate unit content of 30% by mass or more, and the portion below the surface layer portion is also made of an ethylene-vinyl acetate copolymer. In using the synthetic resin sheet, the portion below the surface layer portion of the base sheet has a vinyl acetate unit content of 5 to 50% by mass, more preferably 7 to 30% by mass, especially 10 to 20% by mass. % Of ethylene-vinyl acetate copolymer is preferable from the viewpoint of good physical property retention of the waterproof sheet at low temperatures.

  In the synthetic resin base material sheet, the synthetic resin constituting the lower part of the surface part that becomes the silica-containing surface layer is, if necessary, an inorganic filler such as calcium carbonate, a pigment, a flame retardant, a plasticizer, etc. You may contain 1 type, or 2 or more types.

  The base sheet may not have a fabric layer such as a woven or knitted fabric or a non-woven fabric, or a woven or knitted fabric on the inside or the other surface (the surface opposite to the surface layer portion that becomes the silica-containing surface layer), You may have fabric layers, such as a nonwoven fabric. When the fabric layer is not provided, a waterproof sheet having a high tensile breaking elongation (particularly, a waterproof sheet having a tensile breaking elongation of 300% or more) can be obtained. A high tarpaulin can be obtained.

The base before applying the silica dispersion (a ₁ ) or the silica dispersion (a ₂ ) in terms of flexibility, workability, lightness, strength, tear resistance, etc. of the finally obtained waterproof sheet for tunnel The total thickness of the material sheet is preferably 1.5 mm or more, more preferably 2 mm or more, and further preferably 2 to 5 mm. If the thickness of the base sheet is too thin, it will become thin when the waterproof sheet is stretched (especially when stretched more than 300%) at the time of construction in the tunnel or after construction, and it will be difficult to keep the water-insulation sufficiently. On the other hand, if it is too thick, the handling property at the time of construction to the tunnel tends to be poor.
Moreover, the thickness of the surface layer part (surface layer part before forming a silica containing surface layer) in a base material sheet is 0.05-1 mm, It is 0.1-0.5 mm especially on the surface of a base material sheet. It is preferable from the viewpoint that the silica-containing surface layer can be smoothly formed on the surface layer portion of the substrate sheet by applying the silica dispersion liquid (a ₁ ) or the silica dispersion liquid (a ₂ ) and drying by heating.
Moreover, generally the thickness of the part below the surface layer part in a base material sheet is 0.5-4 mm, It is especially preferable from points, such as intensity | strength, workability, and tear resistance, that it is 1-2 mm.

The content of silica (SiO ₂ ≧ 90%, BET ≧ 80 m ² / g) in the silica dispersion (a ₁ ) or silica dispersion (a ₂ ) applied to the surface of the base sheet made of synthetic resin is determined by silica dispersion relative to the weight of the liquid (a ₁₎ or a silica dispersion (a ₂₎ it is preferably 1-20 mass%, more preferably from 2 to 10 wt%, 3 to 7 wt% Is more preferable.
If the silica dispersion (a ₁ ) or silica dispersion (a ₂ ) contains too little silica (SiO ₂ ≧ 90%, BET ≧ 80 m ² / g), the silica formed on the surface layer of the base sheet The content of silica (SiO ₂ ≧ 90%, BET ≧ 80 m ² / g) in the contained surface layer becomes too small, and a waterproof sheet having high adhesive strength with the concrete forming the tunnel cannot be obtained. On the other hand, if the silica dispersion (a ₁ ) or the silica dispersion (a ₂ ) contains too much silica (SiO ₂ ≧ 90%, BET ≧ 80 m ² / g), the silica dispersion (a ₁ ) or silica During storage of the dispersion (a ₂ ), silica (SiO ₂ ≧ 90%, BET ≧ 80 m ² / g) precipitates and aggregates, resulting in poor storage stability, and the silica dispersion (a ₁ ) or silica dispersion Since the viscosity of the liquid (a ₂ ) becomes too high, workability when the silica dispersion (a ₁ ) or the silica dispersion (a ₂ ) is applied to the substrate sheet is lowered, and uniform application is difficult. Furthermore, due to the relative decrease in the amount of the organic solvent in the silica dispersion, the swelling and / or dissolution action of the surface portion of the base sheet by the organic solvent is reduced, and silica (SiO ₂ ≧ 90%, BET ≧ 80 m ² / g) is not easily held firmly in the surface layer portion.

As an organic solvent used for the preparation of the silica dispersion (a ₁ ) and the silica dispersion (a ₂ ), an ethylene-vinyl acetate copolymer in which the surface layer portion of the base sheet has a vinyl acetate unit content of 30% by mass or more Can be used toluene, xylene, ethyl acetate, tetrahydrofuran, methyl ethyl ketone, etc. Among them, toluene, tetrahydrofuran, methyl ethyl ketone are preferably used from the viewpoint of drying property and solubility of the surface layer resin.
Silica dispersion (a ₁ ) in which silica (SiO ₂ ≧ 90%, BET ≧ 80 m ² / g) is dispersed in an organic solvent that has a dissolving action on the synthetic resin forming the surface layer portion of the base sheet or In addition to the method of the present invention using the silica dispersion (a ₂ ) further containing a thickener, silica (SiO ₂ ≧ 90%, BET ≧ 80 m ² / g) is dispersed in water. When using a dispersion or an aqueous silica dispersion to which a polymer for thickening is further added, or even an organic solvent, it has a dissolving action on the synthetic resin forming the surface layer portion of the base sheet. When a silica dispersion in which silica (SiO ₂ ≧ 90%, BET ≧ 80 m ² / g) is dispersed in an organic solvent that is not shown or has a small dissolving action is used, water as a dispersion medium or a small dissolving action is used. Swelling and / or swelling with respect to the synthetic resin in which the organic solvent forms the surface layer portion of the base sheet Has no dissolving action, so that silica is not firmly held by the base sheet in a state where the silica is taken into the surface layer portion of the base sheet, and has a high adhesive strength to the concrete forming the tunnel. In particular, it is extremely difficult to obtain a waterproof sheet for tunnels having a mortar adhesive strength of 15 N / cm or more.

In the production method of the present invention, silica (SiO ₂ ≧ 90%, BET ≧ 80 m ² / g) is formed on the surface layer portion of the base sheet, regardless of whether the silica dispersion (a ₁ ) or the silica dispersion (a ₂ ) is used. ) In a stable state, the silica-containing surface layer is formed, and a waterproof sheet having high adhesive strength with the concrete forming the tunnel can be obtained. Among them, a silica dispersion liquid further containing a thickener When (a ₂ ) is used, the silica (SiO ₂ ≧ 90%, BET ≧ 80 m ² / g) is more unlikely to fall off from the silica-containing surface layer due to the action of the thickener, and the adhesion to concrete is further increased. A waterproof sheet can be obtained.

As the thickener used for the silica dispersion (a ₂ ), the base sheet is an ethylene-vinyl acetate copolymer (particularly, the ethylene-acetic acid having a vinyl acetate unit content in the surface layer of the base sheet is 30% by mass or more). Vinyl copolymer)), the content of vinyl acetate units is 30 to 90% by mass from the viewpoint of affinity with the ethylene-vinyl acetate copolymer constituting the surface layer portion of the base sheet. In particular, 30 to 70% by mass of an ethylene-vinyl acetate copolymer is preferably used. Silica dispersion amount of the thickener in (a ₂₎ is preferably 20 mass% or less relative to the weight of the organic solvent to form a silica dispersion (a _2), 2-10 wt% It is more preferable. If the addition amount of the thickener is too large, the swelling action of the silica dispersion (a ₂ ) on the surface of the base sheet is lowered, and silica (SiO ₂ ≧ 90%, BET ≧ 80 m) is formed on the surface layer portion of the base sheet. ² / g) is hard to adhere and contain.

In general, the coating amount of the silica dispersion (a ₁ ) or the silica dispersion (a ₂ ) for forming the silica-containing surface layer on the synthetic resin substrate sheet is preferably ² to 50 g / m ² , more preferably ^{30g / m 2, 8~20g / m} 2 is more preferable. Whether the amount of silica dispersion (a ₁ ) or silica dispersion (a ₂ ) applied is too small or too large, silica (SiO ₂ ≧ 90%, BET ≧ 80 m ² / It becomes difficult to form a silica-containing surface layer containing g) in a suitable amount, and in particular, a silica-containing surface layer containing silica (SiO ₂ ≧ 90%, BET ≧ 80 m ² / g) at a concentration of ³⁰ to 200 mg / cm ^3. It tends to be difficult to manufacture a waterproof sheet for tunnels having a high adhesive force with concrete, having a thickness of 5 to 30 μm from the surface of the waterproof sheet.

In general, the drying treatment after applying the silica dispersion (a ₁ ) or the silica dispersion (a ₂ ) to the synthetic resin base sheet is generally performed using the silica dispersion (a ₁ ) or the silica dispersion (a ₂ ). Silica (SiO ₂ ≥90%, BET ≥80m ² / g) can be firmly attached to and contained in the surface layer by performing the reaction at a temperature ranging from the boiling point of the organic solvent used for the preparation to the boiling point + 20 ° C. Moreover, it is preferable from the viewpoint of preventing thermal deterioration of the waterproof sheet.

In producing a tunnel waterproof sheet by the production method of the present invention, in the finally obtained tunnel waterproof sheet, silica (SiO ₂ ≧ 90%, BET ≧ 80 m ² / g) is 30 to 200 mg / cm ³ . It is necessary that the silica-containing surface layer contained at a concentration is formed over a depth of 5 to 30 μm from the surface of the waterproof sheet.
In producing a tunnel waterproof sheet by the production method of the present invention, in the finally obtained tunnel waterproof sheet, the content of silica (SiO ₂ ≧ 90%, BET ≧ 80 m ² / g) in the silica-containing surface layer described above the amount (concentration), it is preferable that such the range of 40~100mg / cm ^3, and more preferably set to be in the range of 45~80mg / cm ^3.
Moreover, when manufacturing the waterproof sheet for tunnels by the manufacturing method of the present invention, in the finally obtained waterproof sheet for tunnels, silica (SiO ₂ ≧ 90%, BET ≧ 80 m ² / g) is 30 to 200 mg / cm. The thickness (depth from the surface) of the silica-containing surface layer contained at a concentration of ³ is preferably in the range of 6 to 20 μm, and more preferably in the range of 7 to 18 μm.

In tunnel waterproof sheets, if the content (concentration) of silica (SiO ₂ ≧ 90%, BET ≧ 80m ² / g) in the silica-containing surface layer is too small, the adhesive strength with concrete tends to be small (especially mortar adhesive strength) However, if the content (concentration) of silica (SiO ₂ ≧ 90%, BET ≧ 80 m ² / g) in the silica-containing surface layer is too high, the strength of the silica-containing surface layer itself decreases. In addition, a decrease in the bonding strength between the silica-containing surface layer and the underlying layer and the occurrence of cracks in the silica-containing surface layer tend to cause a decrease in the mortar adhesion force of the waterproof sheet, cracks on the sheet surface, and the like.
In the waterproof sheet for tunnels, even if the content (concentration) of silica (SiO ₂ ≧ 90%, BET ≧ 80 m ² / g) in the silica-containing surface layer is 30 to 200 mg / cm ³ , the thickness of the silica-containing surface layer If the thickness (depth from the surface) is too small, the adhesive force with concrete tends to be small (particularly the mortar adhesive force tends to be less than 15 N / cm), while the silica-containing surface layer is too thick, Cracks are likely to occur in the silica-containing surface layer.

In producing a waterproof sheet for tunnels by the production method of the present invention, silica (SiO ₂ ≧ 90) can be obtained only by applying the silica dispersion (a ₁ ) or the silica dispersion (a ₂ ) and heat-drying once. %, BET ≧ 80 m ² / g) at a concentration of ³⁰ to 200 mg / cm ³ and a depth (thickness) from the surface of the waterproof sheet in the range of 5 to 30 μm cannot be formed. Until a silica-containing surface layer containing silica (SiO ₂ ≧ 90%, BET ≧ 80 m ² / g) at a concentration of ³⁰ to 200 mg / cm ³ is formed at a depth of 5 to 30 μm from the surface of the waterproof sheet, The application of the silica dispersion liquid (a ₁ ) or the silica dispersion liquid (a ₂ ) and the subsequent heat drying treatment are preferably repeated a plurality of times (overcoating is performed).

Adjustment of the content (concentration) of silica (SiO ₂ ≧ 90%, BET ≧ 80 m ² / g) in the silica-containing surface layer and the depth (thickness) of the silica-containing surface layer from the surface of the waterproof sheet is carried out by adjusting the silica dispersion (a ₁₎ or silica dispersion (a ₂₎ silica (SiO ₂ ≧ 90% in the content of the BET ≧ 80m ² / g), silica dispersion (concentration of the thickener in a ₂₎ in the silica dispersion liquid ( coating amount of a ₁ ) or silica dispersion (a ₂ ), time from application of the dispersion to heat drying, heating drying time, application of silica dispersion (a ₁ ) or silica dispersion (a ₂ ) It can be performed by adjusting the number of times of heat drying (number of overcoating).

The tunnel waterproof sheet obtained by the production method of the present invention has a silica-containing surface layer containing silica (SiO ₂ ≧ 90%, BET ≧ 80 m ² / g) at a concentration of ³⁰ to 200 mg / cm ^{3 from} the surface of the waterproof sheet. By having a thickness (depth) of 5 to 30 μm, when the cement material for concrete formation is applied on the silica-containing surface layer of the waterproof sheet, the calcium component in the cement in the water curing reaction process And silica in the silica-containing surface layer ((SiO ₂ ≥90%, BET ≥80m ² / g) react to form a strong tobermorite, so that the waterproof sheet and concrete are firmly and completely integrated. The

In particular, in carrying out the production method of the present invention, as a base sheet made of synthetic resin, the content of vinyl acetate units in the surface layer portion is 30% by mass or more, more preferably 32% by mass or more, and particularly 32 to 50% by mass of ethylene. -It consists of a vinyl acetate copolymer, and the portion under the surface layer portion is an ethylene-vinyl acetate copolymer, particularly the content of vinyl acetate units is 5 to 50% by mass, more preferably 7 to 30% by mass, especially 10 to 20%. A base sheet made of a mass% ethylene-vinyl acetate copolymer was used, and silica (SiO ₂ ≧ 90%, BET ≧ 80 m ² / g) was added to the surface of the base sheet with respect to the weight of the dispersion. A silica dispersion (a ₁ ) containing at a concentration of ˜20% by weight is applied at a coating amount of 2-50 g / m ² , in particular 5-30 g / m ² , or in the silica dispersion (a ₁ ). The content ratio of vinyl acetate unit as a thickener is 30-9 Wt%, in particular 30 to 70 wt% ethylene - silica dispersion further contain a vinyl acetate copolymer (a ₂₎ a 2 to 50 g / m ^2, in particular coated at a coverage of from 5 to 30 g / m ² Then, when adopting a method in which it is dried by heating at a temperature within the range of the boiling point of the organic solvent to the boiling point + 20 ° C., silica (SiO ₂ ≧ 90%, BET ≧ 80 m ² / g) is added to 30 to 200 mg / cm 3. ^The silica-containing surface layer contained at a ratio (concentration) of ³ is formed over a depth of 5 to 30 μm from the surface of the synthetic resin waterproof sheet, has a high mortar adhesive strength of 15 N / cm or more, and 10 MPa or more It is possible to smoothly manufacture a waterproof sheet for tunnels having extremely high tensile breaking strength and excellent properties.

The tunnel waterproof sheet obtained by the production method of the present invention preferably has a mortar adhesive strength of 15 N / cm or more, more preferably has a mortar adhesive strength of 17 N / cm or more, and 18 N More preferably, it has a mortar adhesive strength of not less than / cm. The upper limit value of the mortar adhesive force is not particularly limited, but is preferably 30 N / cm or less from the viewpoint of production cost.
The tunnel waterproof sheet having a mortar adhesive strength of 15 N / cm or more obtained by the production method of the present invention is firmly bonded to the concrete structure constructed on the waterproof sheet over the entire surface, and the waterproof sheet and the concrete structure In the meantime, there is no gap that becomes a flow path of water that oozes from the ground or the ground, and good waterproofness can be exhibited over a long period of time.

  Here, the “mortar adhesive strength” of the waterproof sheet in the present specification means that a mortar liquid prepared by thoroughly mixing 100 parts by weight of ordinary Portland cement, 200 parts by weight of standard sand and 50 parts by weight of water is adjusted to a predetermined size. About the thing which poured into the thickness (depth) 4cm on the concrete adhesive surface of the cut | disconnected waterproof sheet, and cured the mortar by hardening | curing for 28 days at 20 degreeC in the airtight state, a waterproof sheet is 180 degreeC from one edge part. The average peel strength (N) per 1 cm width of the waterproof sheet when peeled 2 cm at an angle of 10 mm / min. The detailed measurement method of “mortar adhesive strength” is as described in the section of the following examples.

Moreover, in the waterproof sheet for tunnels obtained by the production method of the present invention, the tensile strength at break is preferably 10 MPa or more, more preferably 15 MPa or more, and further preferably 18 MPa or more.
Furthermore, in the waterproof sheet for tunnels obtained by the production method of the present invention, the tensile breaking elongation is not particularly limited, but if it is 300% or more, further 500% or more, particularly 750% or more, a higher waterproof effect is obtained. Obtainable.
In the waterproof sheet for tunnels obtained by the production method of the present invention, the upper limit values of the tensile strength at break and tensile elongation at break are not particularly limited, but the tensile strength at break is preferably 50 MPa or less from the viewpoint of the cost of the resin used, Further, the tensile elongation at break is preferably 1000% or less from the viewpoint of workability.
Here, the “tensile rupture strength” and “tensile rupture elongation” of the waterproof sheet in this specification mean the tensile rupture strength and the tensile rupture elongation measured according to JIS K6773.

  When tunnel construction is performed using the waterproof sheet for tunnel obtained by the manufacturing method of the present invention, the waterproof sheet is formed on the ground and ground part of the tunnel including the primary lining surface, etc. In general, a method of placing a material for forming a concrete structure on the waterproof sheet is employed. In particular, the tunnel waterproof sheet obtained by the manufacturing method of the present invention is suitably used for the urban NATM construction method, especially a tunnel with improved airtightness and water shielding called water tight. A waterproof sheet is laid to prevent ingress of groundwater from outside the tunnel.

In the construction method described above, the waterproof sheet laid on the ground and ground of the tunnel including the primary lining surface is placed when the concrete structure that becomes the tunnel body is laid from the inside of the waterproof sheet after the waterproof sheet is laid. It is necessary to prevent problems such as tearing of the waterproof sheet due to the pressure of concrete, or stretching of the waterproof sheet in the concave portion of the ground and local stress applied to the waterproof sheet.
The tunnel waterproof sheet having a high tensile fracture strength of 10 MPa or more obtained by the production method of the present invention, particularly a tunnel waterproof sheet having a high tensile fracture strength of 10 MPa or more and a high tensile fracture elongation of 300% or more, At that time, it is not torn by the pressure of the cast concrete, and even if the waterproof sheet is stretched by the concave portion of the ground and the waterproof sheet is locally stressed, the damage does not occur. In addition, the tunnel waterproof sheet having high tensile breaking strength and high tensile breaking elongation obtained by the production method of the present invention is less likely to be damaged even if stress is applied to the waterproof sheet after the tunnel is constructed, Good waterproof performance can be maintained over a long period of time.

  When performing waterproofing work in the tunnel using the waterproof sheet obtained by the manufacturing method of the present invention, the work may be performed using a single waterproof sheet or a plurality of waterproof sheets depending on the construction content or the like. Construction may be performed using a sheet. When construction is performed using a plurality of waterproof sheets, the end portions of the waterproof sheets may be joined, or the end portions of the waterproof sheet and the end portions of other sheets may be joined. The joining of the end portions can be performed by, for example, a heat fusion method using high frequency dielectric heating or high frequency induction heating, a method using an adhesive, or the like.

Hereinafter, the present invention will be specifically described with reference to examples and the like, but the present invention is not limited to the following examples.
In the following examples, the content of silicon dioxide in silica, the BET specific surface area of silica, the tensile strength at break of the waterproof sheet, the tensile elongation at break, the thickness of the silica-containing surface layer in the waterproof sheet, the silica content in the silica-containing surface layer, and Measurement of the adhesive strength of the mortar of the waterproof sheet and determination of the presence or absence of water leakage inside the tunnel were performed as follows.

(1) Content of silicon dioxide in silica:
The content of silicon dioxide (SiO ₂ ) in silica was determined from the following mathematical formula (i).

SiO ₂ content (% by mass) = 99.80 (% by mass) − (C _A + C _B + C _C + D) (i)

[Wherein, C _A is the content (mass%) of Al ₂ O ₃ in silica, C _B is the content (mass%) of Fe ₂ O ₃ in silica, and C _C is the content of Na ₂ O in silica. Content (mass%), D shows the weight loss rate (mass%) with respect to the mass of the silica before a heating when heating a silica at 105 degreeC for 2 hours, and also heating at 1000 degreeC for 1 hour. The contents of Al ₂ O ₃ , Fe ₂ O ₃ and Na ₂ O in silica were measured using fluorescent X-rays. In addition, in the above formula (i), the reason why the fixed value at the time of obtaining the content of SiO ₂ is not 100% by mass but 99.80% by mass is that trace impurities (TiO ₂ , CaO, MgO in silica) And SO ₄ ) are contained in an amount of 0.20% by mass, and the value obtained by subtracting the content of the trace impurities is adopted as a fixed value. ]

(2) BET specific surface area of silica:
The BET specific surface area of silica was measured by the BET method using an automatic specific surface area measuring device “Gemini 2375” manufactured by Shimadzu Corporation.

(3) Tensile breaking strength and tensile breaking elongation of the waterproof sheet:
Both the tensile strength at break and the tensile elongation at break of the waterproof sheet were measured according to JIS K6773.
Specifically, the tensile strength at break of the waterproof sheet is determined under the conditions of a temperature of 20 ° C. and a humidity of 65% (RH) using an Instron 5566 tester according to the method described in Section 7 of JIS K 6773. went.
In addition, the tensile elongation at break of the waterproof sheet was measured under the conditions of a temperature of 20 ° C. and a humidity of 65% (RH) using an Instron 5566 tester according to the method described in 7.6 of JIS K6773. went.

(4) Thickness of the silica-containing surface layer in the waterproof sheet:
The waterproof sheet obtained in the following example was cut with a microtome in the width direction, and the cut surfaces were photographed at three locations with an electron microscope (1000 times magnification) at intervals of 50 cm (the length of the width at which each portion was photographed) Thickness = 0.1 mm), the thickness (depth) of the silica-containing surface layer at each photographing location was measured, and the average value of the three locations was taken as the thickness of the silica-containing surface layer.

(5) Content ratio of silica in the silica-containing surface layer of the waterproof sheet:
From the waterproof sheet photographed with the electron microscope in (4) above, cut out a test piece of length x width = 3 cm x 3 cm), put the test piece in a crucible and heat it to 800 ° C in an electric furnace to remove all organic matter. Vaporize and color the remaining ash by adding hydrochloric acid and ammonium molybdate, and measure the content of silica contained in the test piece against a calibration curve prepared from a sample of known concentration (Molybdenum blue method) ), The content ratio of silica in the silica-containing surface layer of the waterproof sheet was determined from the following mathematical formula (ii). In addition, in the waterproof sheet, silica may be included in a portion below the silica-containing surface layer, but since the amount thereof is extremely small, the silica contained below the silica-containing surface layer also contains silica. Treated as if it were contained in the surface layer.

Content ratio of silica in the silica-containing surface layer (mg / cm ³ ) = (W / V) × 100 (ii)

[Wherein, W = content of the silica contained in the test piece (mg), V = volume of the silica-containing surface layer in the test piece = thickness of the silica-containing surface layer (cm) × vertical dimension of the test piece (cm) X Indicates the horizontal dimension (cm) of the test piece. ]

(8) Mortar adhesive strength of waterproof sheet:
(I) Ordinary Portland cement (ordinary Portland cement manufactured by Taiheiyo Cement Co., Ltd.) and dried Toyoura standard sand are mixed well at a ratio of sand: cement = 2: 1 (mass ratio), and 0.5 mass of water is mixed therewith. Part was added and stirred well to prepare a mortar solution.
(Ii) A rectangular test piece of width × length = 4 cm × 16 cm is cut and collected from the waterproof sheet along the length direction, and the test piece is width × length × depth = 4 cm × 16 cm × 4 cm. The bottom of the mold is laid with the surface for adhering the mortar facing upward, and the mortar liquid prepared in (i) above is poured from above, and bubbles are removed from the mortar by stirring and vibration. The mold was placed in a sealed container so as not to evaporate and cured at 20 ° C. for 28 days.
(Iii) After curing is completed, the mortar piece to which the waterproof sheet is adhered is taken out from the mold, the surface to which the waterproof sheet is adhered is turned up, and one end of the waterproof sheet in the longitudinal direction is peeled off 2 cm from the mortar piece. Along with the width direction of the peeled end portion, a polyester canvas (Kuraray Co., Ltd. “E5 base fabric” piece (width × length = 4 cm × 20 cm) is firmly connected so as not to come off with a stapler. As shown in Fig. 2, peel off at an angle of 180 ° at a speed of 10 mm / min until peeling 2 cm in the length direction of the sheet (excluding the length part peeled off to connect the polyester canvas pieces). In this case, the stress was continuously measured, and after the peeling of 2 cm was completed, the average peeling strength (N) was calculated from the chart. Since the width of the test piece was 4 cm, the value calculated above was divided by 4 to obtain the width. Peel per cm The stress (N / cm) at the time of separation was determined, and three test pieces were cut and collected for each waterproof sheet, the same test as described above was performed, and the average value of the three test pieces was determined as the mortar adhesive strength. It was.

(9) Judgment of leakage inside tunnel:
A watertight tunnel was constructed by the urban NATM construction method at a point 20 meters underground. Specifically, as shown in FIG. 2, a horizontal hole having an elliptical cross section (major axis about 15 m, minor axis about 10 m) is excavated at a point 20 m underground, and concrete is sprayed on the upper half of the horizontal hole, and the lower half is blown. After placing concrete, place the silica-containing layer of the waterproof sheet 1 facing the atmosphere (place the surface without the silica-containing layer in contact with the concrete) and cover it with concrete 2 (cover A tunnel was constructed by driving rock bolts 3 with a concrete thickness of about 20 cm). After the construction was completed, the groundwater level was restored, and the presence of water leakage into the tunnel was observed after 28 days.

The types and contents of the ethylene-vinyl acetate copolymer and silica used in the following examples are as shown below.
[Ethylene-vinyl acetate copolymer]
○ Ethylene-vinyl acetate copolymer (I) :
"Evaflex EV45LX" manufactured by Mitsui DuPont Polychemical Co., Ltd.
(Content ratio of vinyl acetate unit = 46 mass%, ethylene unit content ratio = 54 mass%, MFR = 2.5 g / 10 min)
○ Ethylene-vinyl acetate copolymer (II) :
“Ultrasen 631” manufactured by Tosoh Corporation (vinyl acetate unit content ratio = 20 mass%, ethylene unit content ratio = 80 mass%, MFR = 1.5 g / 10 min)
○ Ethylene-vinyl acetate copolymer (III) :
“Ultrasen 6M51A” manufactured by Tosoh Corporation (vinyl acetate unit content ratio = 15 mass%, ethylene unit content ratio = 85 mass%, MFR = 0.6 g / 10 min)
○ Ethylene-vinyl acetate copolymer (IV) :
“Evaflex 420P” manufactured by Dainippon Ink Co., Ltd. (vinyl acetate unit content ratio = 60 mass%, ethylene unit content ratio = 40 mass%, MFR = 15 g / 10 min)
○ Ethylene-vinyl acetate copolymer (V) :
“Evaflex P1905” manufactured by Mitsui DuPont Polychemical Co., Ltd. (vinyl acetate unit content: 19% by mass, ethylene unit content: 81% by mass, MFR = 2.5 g / 10 min)
○ Ethylene-vinyl acetate copolymer (VI) :
“Evaflex P2505” manufactured by Mitsui DuPont Polychemical Co., Ltd. (vinyl acetate unit content ratio = 25 mass%, ethylene unit content ratio = 75 mass%, MFR = 2.0 g / 10 min)

[silica]
○ Silica (i) :
“Nippal LP” manufactured by Tosoh Silica Co., Ltd. (silicon dioxide content = 93 mass%, BET specific surface area = 200 m ² / g)
○ Silica (ii) :
“Nip seal E200A” manufactured by Tosoh Silica Co., Ltd. (content of silicon dioxide = 94 mass%, BET specific surface area = 140 m ² / g)
○ Silica (iii) :
“Nip seal E75” manufactured by Tosoh Silica Co., Ltd. (silicon dioxide content = 94 mass%, BET specific surface area = 45 m ² / g)

Example 1
(1) 50 parts by mass of ethylene-vinyl acetate copolymer (I) is mixed with 50 parts by mass of ethylene-vinyl acetate copolymer (II), melt-kneaded at 170 ° C, and then extruded and cut into a rod shape at 170 ° C. Thus, pellets of the ethylene-vinyl acetate copolymer composition for the A layer were produced.
(2) The pellet for the A layer produced in the above (1) is supplied to one melt kneader of a two-layer extrusion type extruder (manufactured by Hitachi Zosen), and one T die (die lip width 220 cm, From the die temperature (200 ° C), melt-extruded into a sheet (layer A), and from the other T-die (die lip width 220 cm, die temperature 200 ° C), the ethylene-vinyl acetate copolymer (III) was melt-extruded into a sheet (B layer), laminated both immediately after extrusion, laminated sheet (base sheet) having a width of 220 cm, A layer thickness of 0.4 mm, and B layer thickness of 1.6 mm (total sheet thickness) 2 mm). In addition, the content rate (average value) of the vinyl acetate unit in the ethylene-vinyl acetate copolymer composition which comprises A layer was 33 mass%.

(3) 5 parts by mass of silica (i), 85 parts by mass of toluene and a 50% methanol solution of ethylene-vinyl acetate copolymer (“Coponil 9484” manufactured by Nippon Synthetic Chemical Industry Co., Ltd., ethylene-vinyl acetate copolymer) A silica dispersion was prepared by mixing 10 parts by mass of 80% by mass of vinyl acetate units in the coalesced mixture and stirring sufficiently.
(4) After applying the silica dispersion prepared in (3) above with a gravure roll on the surface of the layer A side of the laminated sheet (base sheet) produced in (2) above at a rate of 10 g / m ² And dried at 130 ° C. for 1 minute. This application / drying operation was repeated three times to produce a waterproof sheet shown in FIG. 3A having a silica-containing surface layer in the surface layer portion of the A layer.
(5) Tensile rupture strength, tensile rupture elongation, thickness (depth) of the silica-containing surface layer from the surface of the layer A, silica content in the silica-containing surface layer, mortar adhesive strength of the waterproof sheet obtained in (4) above When the presence or absence of water leakage when installed inside the tunnel was measured or evaluated by the method described above, it was as shown in Table 1 below.
FIG. 4 is a photograph of a cross section (upper part of layer A) of the waterproof sheet obtained in Example 1 taken with an electron microscope (“S-2600N type” manufactured by Hitachi High-Technologies Corporation) (1000 × magnification). Yes, as shown in FIG. 4, a silica-containing surface layer having a thickness (depth) of 13 μm was formed on the surface layer portion of the waterproof sheet. Silica was slightly contained below the silica-containing surface layer, but all was contained within a depth of 0.1 mm from the outermost surface of the waterproof sheet, and was not contained deeper than that.

Example 2
(1) 5 parts by mass of silica (ii), 90 parts by mass of toluene and 5 parts by mass of ethylene-vinyl acetate copolymer (I) were mixed and sufficiently stirred to prepare a silica dispersion.
(2) The same as Example 1 except that the silica dispersion prepared in (1) of this Production Example was used in Example 1 instead of the silica dispersion prepared in (3) of Example 1. Operation was performed to produce a waterproof sheet having a silica-containing surface layer in the surface layer portion of the A layer.
(3) Tensile rupture strength, tensile rupture elongation, thickness (depth) of the silica-containing surface layer from the surface of the layer A, content of silica in the silica-containing surface layer, mortar adhesive strength of the waterproof sheet obtained in (2) above When the presence or absence of water leakage when installed inside the tunnel was measured or evaluated by the method described above, it was as shown in Table 1 below.

Example 3
(1) 60 parts by mass of an ethylene-vinyl acetate copolymer (IV), 40 parts by mass of an ethylene-vinyl acetate copolymer (VI), 10 parts by mass of calcium carbonate (“Shirashin Grass O” manufactured by Shiraishi Calcium Co., Ltd.) and silicon 1 part by mass of a system lubricant (“LBT-100” manufactured by Sakai Chemical Co., Ltd.) was melt-kneaded at 170 ° C., then extruded into a rod shape and cut to produce pellets for the A layer.
(2) 25 parts by mass of an ethylene-vinyl acetate copolymer (IV), 75 parts by mass of an ethylene-vinyl acetate copolymer (V), 10 parts by mass of calcium carbonate (“Shirashin Grass O” manufactured by Shiraishi Calcium Co., Ltd.) and silicon 1 part by mass of a system lubricant (“LBT-100” manufactured by Sakai Chemical Co., Ltd.) was melt-kneaded at 170 ° C., then extruded into a rod shape and cut to produce pellets for the B layer.

(3) Using the pellets for the B layer produced in the above (2), kneading and molding at 170 ° C. with a calender roll (Nippon Roll, reverse L4, diameter 56 cm, width 152 cm), width 150 cm, thickness A 0.4 mm sheet was obtained.
(4) The sheet manufactured in the above (3) is charged from the lower side of the calender roll, melted in the same manner as in the above (2), and put out by a calender, the same with a width of 150 cm and a thickness of 0.4 mm Sheets made of an ethylene-vinyl acetate copolymer composition were stacked and bonded together to obtain a sheet having a width of 150 cm and a thickness of 0.8 mm. This operation was further repeated twice to finally produce a B layer sheet having a width of 150 cm and a thickness of 1.6 mm.
(5) The sheet for the B layer obtained in the above (4) is charged from the lower side of the same calender roll as above, and the same calendar is used from above using the pellet for the A layer manufactured in the above (1). It is melted by a roll and discharged onto a 0.4 mm thick sheet (A layer) and bonded onto the B layer sheet. The width is 150 cm, and the total thickness is 2 mm (A layer 0.4 mm, B layer). 1.6 mm) laminated sheet (base material sheet) was produced.

(6) On the surface of layer A of the laminated sheet (base material sheet) produced in (5) above, the same silica dispersion prepared in (3) of Example 1 is gravure roll at a rate of 10 g / m ² Then, the coating was dried at 130 ° C. for 1 minute. This coating / drying operation was repeated three times to produce a waterproof sheet having a silica-containing surface layer in the surface layer portion of the A layer.
(7) Tensile rupture strength, tensile rupture elongation, thickness (depth) of the silica-containing surface layer from the surface of the layer A, content of silica in the silica-containing surface layer, mortar adhesive strength of the waterproof sheet obtained in (6) above When the presence or absence of water leakage when installed inside the tunnel was measured or evaluated by the method described above, it was as shown in Table 1 below.

<< Comparative Example 1 >>
(1) In (3) of Example 1, the amount of silica added was changed to 1 part by mass when preparing the silica dispersion, and the number of times of application of the silica dispersion in the gravure roll in (4) of Example 1 was determined. A waterproof sheet was produced in the same manner as in Example 1 except that it was changed once.
(2) Tensile rupture strength, tensile rupture elongation, thickness (depth) of the silica-containing surface layer from the surface of the layer A, silica content in the silica-containing surface layer, mortar adhesive strength When the presence or absence of water leakage when installed inside the tunnel was measured or evaluated by the method described above, it was as shown in Table 2 below.

<< Comparative Example 2 >>
(1) In Example 1, A layer was formed using the pellet which added the same silica (i) used in Example 1 in the ratio of 1 mass% at the time of manufacture of the pellet for A layer, and also silica. A waterproof sheet shown in FIG. 3B in which silica was dispersed throughout the layer A was produced in the same manner as in Example 1 except that the dispersion liquid was not applied.
(2) Tensile rupture strength, tensile rupture elongation, thickness (depth) of the silica-containing surface layer from the surface of the layer A, silica content in the silica-containing surface layer, mortar adhesive strength When the presence or absence of water leakage when installed inside the tunnel was measured or evaluated by the method described above, it was as shown in Table 2 below.

<< Comparative Example 3 >>
(1) A waterproof sheet having a silica-containing surface layer in the surface layer portion of the A layer was produced in the same manner as in Example 1 except that silica (iii) was used instead of silica (i).
(2) Tensile rupture strength, tensile rupture elongation, thickness (depth) of the silica-containing surface layer from the surface of the layer A, silica content in the silica-containing surface layer, mortar adhesive strength When the presence or absence of water leakage when installed inside the tunnel was measured or evaluated by the method described above, it was as shown in Table 2 below.

<< Comparative Example 4 >>
(1) Ethylene-vinyl acetate copolymer (I): ethylene-vinyl acetate copolymer (II) = 30: 70 (mass ratio) A waterproof sheet having a silica-containing surface layer in the surface layer portion of the A layer was produced in the same manner as in Example 1 except that the above was changed.
(2) Tensile rupture strength, tensile rupture elongation, thickness (depth) of the silica-containing surface layer from the surface of the layer A, silica content in the silica-containing surface layer, mortar adhesive strength When the presence or absence of water leakage when installed inside the tunnel was measured or evaluated by the method described above, it was as shown in Table 2 below.

<< Comparative Example 5 >>
(1) In the same manner as in Example 1 except that the organic solvent used for preparing the silica dispersion in Example 1 (3) was changed from toluene to methanol, the surface layer portion of the A layer has a silica-containing surface layer. A waterproof sheet was produced.
(2) Tensile rupture strength, tensile rupture elongation, thickness (depth) of the silica-containing surface layer from the surface of the layer A, silica content in the silica-containing surface layer, mortar adhesive strength The presence or absence of water leakage when installed inside the tunnel was measured or evaluated by the method described above, and as shown in Table 3 below.

<< Comparative Example 6 >>
(1) In the preparation of the silica dispersion in Example 1 (3), except that 85 parts by mass of water was used instead of 85 parts by mass of toluene, the surface layer part of the A layer was used in the same manner as in Example 1. A waterproof sheet having a silica-containing surface layer was produced.
(2) Tensile rupture strength, tensile rupture elongation, thickness (depth) of the silica-containing surface layer from the surface of the layer A, silica content in the silica-containing surface layer, mortar adhesive strength The presence or absence of water leakage when installed inside the tunnel was measured or evaluated by the method described above, and as shown in Table 3 below.

As can be seen from the results in Tables 1 to 3, in Examples 1 to 3, a base sheet made of synthetic resin [consisting of an ethylene-vinyl acetate copolymer having a vinyl acetate unit content of 30% by mass or more. Silica (SiO ₂ ≧ 90%, BET ≧ 80 m ² / g) is coated on the surface of the base material sheet consisting of the surface layer (A layer) and the main body (B layer) made of ethylene-vinyl acetate copolymer. Dispersed in an organic solvent (toluene) having a dissolving action on the surface layer part (A layer) of the material, and further contains a thickener (ethylene-vinyl acetate copolymer having a vinyl acetate unit content of 30% by mass or more) The silica-containing surface layer in which the concentration of silica (SiO ₂ ≧ 90%, BET ≧ 80 m ² / g) is in the range of ³⁰ to 200 mg / cm ³ is applied to the surface of the waterproof sheet. Tunnel protection over a depth in the range of 5 to 30 μm By producing the sheet, the adhesive strength of the mortar is as high as 15 N / cm or more (18.7 to 20.7 N / cm), and the tensile strength at break is as high as 10 MPa or more (19.8 to 23.4 MPa). A waterproof sheet for tunnels having an elongation of as high as 300% or more (825 to 1079%), excellent adhesion to concrete, and causing no water leakage when constructed in a tunnel has been obtained.

In contrast, in the waterproof sheet for tunnel manufactured in Comparative Example 1, the content (concentration) of silica in the silica-containing surface layer is too small as 18 mg / cm ^3, and the thickness of the silica-containing surface layer from the waterproof sheet surface is too small. By being too thin as 4 μm, both the silica content (concentration) in the silica-containing surface layer and the thickness of the silica-containing surface layer are out of the scope of the present invention, so that the mortar adhesive force is as small as 8.3 N / cm. Adhesion to concrete was inferior, and water leakage occurred when constructed in the tunnel.
Moreover, in the waterproof sheet for tunnels manufactured in Comparative Example 2, the silica content (concentration) in the silica-containing surface layer is too small as 10 mg / cm ^3, and the thickness of the silica-containing surface layer from the waterproof sheet surface is 400 μm. It is too thick, and both the content (concentration) of silica in the silica-containing surface layer and the thickness of the silica-containing surface layer are out of the scope of the present invention. The adhesiveness was inferior, and water leakage occurred when constructed in the tunnel.

In Comparative Example 3, silica having a small BET specific surface area of 45 m ² / g was used, and silica (SiO ₂ ≧ 90%, BET ≧ 80 m ² / g) having a BET specific surface area of 80 m ² / g or more was not used. In the waterproof sheet for tunnel manufactured in Comparative Example 3, the content (concentration) of silica in the silica-containing surface layer and the thickness of the silica-containing surface layer from the surface of the waterproof sheet were within the range defined by the present invention, but the mortar Adhesive strength was as small as 8.0 N / cm and poor adhesion to concrete, and water leakage occurred when constructed in a tunnel.
In Comparative Example 4, a synthetic resin sheet made of an ethylene-vinyl acetate copolymer having a vinyl acetate unit content of 27.8% by mass as the base sheet is used, and silica (SiO ₂ ≧ 90%) is used as the silica dispersion. , BET ≧ 80 m ² / g) in toluene (containing a thickener) and toluene (silica) with respect to the ethylene-vinyl acetate copolymer forming the surface layer portion of the base sheet In the waterproof sheet for tunnels produced in Comparative Example 4 because the dissolution action of the dispersion medium of the dispersion liquid is insufficient, the content (concentration) of silica in the silica-containing surface layer and the surface of the waterproof sheet in the silica-containing surface layer Although the thickness was within the range specified in the present invention, the mortar adhesive strength was as small as 5.3 N / cm and the adhesion to concrete was inferior, and water leakage occurred when constructed in the tunnel. I started.

In Comparative Example 5, a dispersion (containing a thickener) in which silica (SiO ₂ ≧ 90%, BET ≧ 80 m ² / g) is dispersed in methanol is used as the silica dispersion, and methanol (dispersion of silica dispersion) is used. Since the medium does not wait for the dissolving action on the ethylene-vinyl acetate copolymer forming the surface layer portion of the base sheet, the tunnel waterproof sheet produced in Comparative Example 5 contains silica in the silica-containing surface layer. The amount (concentration) is too small, and the thickness of the silica-containing surface layer from the surface of the waterproof sheet is too thin, both of which are out of the range defined in the present invention, so that the mortar adhesive strength is 5.1 N / cm. Small and inferior to concrete, water leaked when constructed in a tunnel.
In Comparative Example 6, a dispersion (containing a thickener) in which silica (SiO ₂ ≧ 90%, BET ≧ 80 m ² / g) is dispersed in water is used as the silica dispersion, and water (dispersion of the silica dispersion) is used. Medium) does not wait for the dissolving action on the ethylene-vinyl acetate copolymer forming the surface layer portion of the base sheet, so that the tunnel waterproof sheet produced in Comparative Example 6 contains silica in the silica-containing surface layer. The amount (concentration) is too small, and the thickness of the silica-containing surface layer from the waterproof sheet surface is too thin, both of which are out of the range defined in the present invention, so that the mortar adhesive strength is 0.5 N / cm. Small and inferior to concrete, water leaked when constructed in a tunnel.

  By the manufacturing method of the present invention, it is firmly bonded and integrated with a concrete tunnel structure, and even if a long time elapses after the construction, there is no gap between the waterproof sheet and the concrete structure, and the construction is performed in the tunnel. Even if stress is applied to the waterproof sheet during or after construction, it will not cause damage or other problems, and it will be able to smoothly prevent water that has exuded from the ground and the ground from leaking into the tunnel structure. A sheet can be manufactured smoothly.

It is the figure which showed the measuring method of the mortar adhesive force of a waterproof sheet. It is the figure which showed typically the tunnel structure which constructed the waterproof sheet. It is the figure [(a)] which showed typically the section of the waterproof sheet obtained in Example 1, and the figure [(b)] which showed the section of the waterproof sheet obtained in comparative example 2 typically. 2 is an electron micrograph of a cross section (A layer portion) of the waterproof sheet obtained in Example 1. FIG.

Explanation of symbols

1 Tarpaulin 2 Lining concrete 3 Rock bolt

Claims (5)

On the surface of the base sheet made of synthetic resin, silica having a silicon dioxide content of 90% by mass or more and a BET specific surface area of 80 m ² / g or more is applied to the synthetic resin constituting the surface layer portion of the base sheet. A silica dispersion (a ₁ ) dispersed in an organic solvent exhibiting a dissolving action, or a thickener having an affinity for the synthetic resin constituting the surface layer portion of the substrate sheet in the silica dispersion (a ₁ ) A silica-containing surface layer containing 30 to 200 mg / cm ³ of the silica at a depth of 5 to 30 μm from the surface of the base sheet after applying the silica dispersion (a ₂ ) further contained and then drying by heating. A method for producing a waterproof sheet for tunnels made of a synthetic resin having a silica-containing surface layer.   The method for producing a waterproof sheet for tunnels according to claim 1, wherein the thickener having affinity for the base resin and the synthetic resin constituting the surface layer portion of the base sheet is made of an ethylene-vinyl acetate copolymer.   Ethylene-acetic acid in which the synthetic resin constituting the surface layer portion of the base sheet and the thickener having an affinity for the synthetic resin constituting the surface layer portion of the base sheet are 30% by mass or more of the structural unit content derived from vinyl acetate The manufacturing method of the waterproof sheet for tunnels of Claim 1 or 2 which consists of a vinyl copolymer.   The manufacturing method of the waterproof sheet for tunnels of any one of Claims 1-3 which manufactures the waterproof sheet for tunnels whose mortar adhesive force is 15 N / cm or more. As a base sheet made of synthetic resin, the surface layer portion is made of an ethylene-vinyl acetate copolymer having a vinyl acetate unit content ratio of 30% by mass or more, and the portion under the surface layer portion is made of an ethylene-vinyl acetate copolymer. Using a base material sheet, on the surface of the base material sheet, silica having a silicon dioxide content of 90% by mass or more and a BET specific surface area of 80 m ² / g or more is 1 to 20 masses based on the mass of the dispersion. % Of silica dispersion (a ₁ ) is applied at a coating amount of 2-50 g / m ² , or the content of vinyl acetate units in the silica dispersion (a ₁ ) is 30% by mass or more. A silica dispersion (a ₂ ) further containing an ethylene-vinyl acetate copolymer as a thickener was applied at a coating amount of ² to 50 g / m ² and then dried by heating to obtain a surface layer portion of the base sheet. And 30 to 20 of the silica. The manufacturing method of the waterproof sheet for tunnels of any one of Claims 1-4 which forms the silica containing surface layer contained at 0 mg / cm < ³ > over the depth of 5-30 micrometers from the surface of a base material sheet.