JP2009084840A - Waterproof sheet for building substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a waterproof sheet for a building substrate, which hardly causes the intrusion of water from the periphery of a nail hole even if a nail and the like are driven in construction, which fills a microspace around the nail hole by making a water-absorbing polymer resin expanded by water absorption, even if the water intrudes, and which is excellent in water sealability and its durability. <P>SOLUTION: This waterproof sheet for the building substrate is a multilayer structure in which a nonwoven fabric with a swelling layer composed of the water-absorbing polymer resin is held by being sandwiched between two layers of synthetic resin films. The 5-40 g/m<SP>2</SP>water-absorbing polymer resin with a water absorption expansion magnification more than 200 times is formed as the swelling layer. The waterproof sheet is formed in such a manner that an occupied area of the swelling layer with respect to the nonwoven fabric is in the range of 40-100%. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a waterproof sheet for construction, and more particularly, is a base sheet for an opening around a window, an upper part of a veranda headboard, and an eaves part at the time of residential construction. The present invention relates to a waterproof sheet for building foundations that is excellent in water-stopping, durability, and workability from holes such as nails.

Conventionally, the waterproofing sheet for draining a house is mainly a sheet formed by impregnating a base paper with straight asphalt or pitch, or a sheet in which a rubber component is coated or laminated on a nonwoven fabric or a woven fabric of synthetic fibers. Is.

The water draining waterproof sheet is required to have a long-term waterproof property and a waterproof property to a hole in a portion fixed with a nail or a tucker. In particular, when water stoppage with respect to the nail hole is emphasized and a large shape change occurs in the sheet, the hole opened by the nail further expands, and rainwater or the like enters from there to cause so-called water leakage. Furthermore, there is a possibility that the vicinity of the water leakage portion may be corroded or mold may be generated due to water leakage.
Conventionally, many sheets using the above asphalt-based or synthetic rubber-based water-stopping material have been used.
However, in the case of a sheet using asphalt water-stopping material, not only the problem of nail holes, but also cracks (cracks) are likely to occur due to bending in low temperature environments such as winter, and problems such as water leakage from this part. May occur. Furthermore, since the weight per unit weight is about 700 g / m ² , it is difficult to handle, and there is a problem in safety especially in work at a high place.
In addition, in the case of a sheet using a synthetic rubber-based water-stopping material, the synthetic rubber gradually deteriorates or deteriorates due to heat or light due to long-term use, and cures or shrinks. The gap between the sheets is enlarged and the water stoppage is impaired.
Patent Document 1 discloses a water shielding sheet obtained by sticking a vinyl chloride resin film or sheet to one or both surfaces of a nonwoven fabric containing a water-absorbing resin. May cause the plasticizer to elute and lose flexibility, resulting in insufficient water stoppage, or if impact is applied at low temperatures, the sheet surface may crack and may not provide water stoppage. . Moreover, there is a concern that many dioxins are generated at the time of incineration disposal, which may lead to environmental problems. In addition, the elution of plasticizers containing environmental hormones may cause an impact on the human body.
Further, Patent Document 2 discloses an architectural waterproof sheet in which a polyethylene film, a swelling layer, and a nonwoven fabric are bonded to obtain moisture permeability and water-stopping properties. However, a thin portion of the nonwoven fabric is damaged during laying construction. The swelling agent oozes out from the damaged non-woven fabric portion, and there is a risk that the water stoppage is impaired.
JP-A-5-162258 JP 2002-316373 A

  An object of the present invention is to provide a waterproof sheet for building foundations that is excellent in water-stopping of holes by nails, tuckers, and the like, has durability toughness, is light and easy to handle.

As a result of intensive studies to achieve the above-mentioned problems, the present invention has been achieved with remarkable effects.
That is, the present invention provides (1) a multilayer structure in which a nonwoven fabric having a swollen layer made of a water-absorbing polymer resin is sandwiched between two synthetic resin films, and the swollen layer absorbs and expands water. Waterproofing for building foundations characterized in that 5-40 g / m ^{2 of} water-absorbing polymer resin with a magnification greater than 200 times is formed and the area occupied by the swelling layer with respect to the nonwoven fabric is 40-100% It is a sheet.

  Moreover, (2) is the waterproof sheet for building foundations according to (1), wherein the bonding area ratio between the nonwoven fabric and the synthetic resin film is 30 to 100%.

  Moreover, in (3), the film thickness of one synthetic resin film is 50 to 300 μm, the film thickness of the other synthetic resin film is 5 to 60 μm, and the static friction coefficient between the two films is 0.2 or more. The waterproof sheet for architectural foundations according to (1) or (2), which is characterized in that

Moreover, the waterproof sheet for building foundations according to any one of (1) to (3), wherein the nonwoven fabric is (4) formed of synthetic fibers having a basis weight of 30 to 300 g / m ² .

Moreover, (5) is the waterproof sheet for building foundations according to any one of (1) to (4), wherein at least one of the two-layer synthetic resin films contains a linear low-density polyethylene resin.

Also, in (6), fix to the plywood with a JIS S6030 regulation No. 3 U stapler spelling needle, and in accordance with JIS A 5430 10.6 (water permeability test), put water to a height of 50 mm in the tube and leave it for 24 hours. water leakage area of the plywood when it is waterproof sheet for building foundation according to any of characterized in that it does not exceed ^{1cm 2 (1) ~ (5} ).

The waterproof sheet for building foundations of the present invention is a multilayer structure in which a nonwoven fabric having a swelling layer made of a water-absorbing polymer resin is sandwiched between two synthetic resin films, and the swelling layer absorbs water. Waterproofing for building foundations, characterized in that 5-40 g / m ^{2 of} water-absorbing polymer resin with a magnification of greater than 200 is formed and the area occupied by the swelling layer with respect to the nonwoven fabric is 40-90% It is a sheet. Since the waterproof sheet for building foundations of the present invention has a synthetic resin film that is waterproof and has good water resistance in nail holes and a swelling layer of a water-absorbing polymer resin having a water absorption expansion ratio of more than 200 times, a nail or the like is attached to the sheet. Even if it is struck, water does not easily enter from the periphery of the nail hole, and moisture that has entered from the periphery of the nail hole is absorbed by the water-absorbing polymer resin, and the resin swells and fills the fine space around the nail. It prevents water from penetrating and exhibits excellent water stopping properties. Further, in the present invention, since the swelling layer is sandwiched between two synthetic resin films, even when the water-absorbing polymer resin absorbs water and gels, the water-absorbing polymer resin oozes out on the front and back surfaces of the sheet. Further, the swelling of the gelled water-absorbing polymer resin in the vertical direction (sheet thickness direction) is suppressed, so that the gaps in the nail hole portions are efficiently and quickly filled. In addition, since the nonwoven fabric is sandwiched between two layers of synthetic resin films, a lightweight and tough sheet with excellent durability can be obtained.

As shown in FIG. 1, the waterproof sheet for building foundations of the present invention is a multilayer structure in which a nonwoven fabric is sandwiched between two layers of synthetic resin films, and water is absorbed in the surface, back surface or nonwoven fabric of the nonwoven fabric. A swelling layer formed of 5 to 40 g / m ² of a water-absorbing polymer resin having an expansion ratio of more than 200 times is provided, and an area occupied by the swelling layer with respect to the nonwoven fabric is 40 to 100%. It is a waterproof sheet for architectural foundations characterized.

The synthetic resin film used in the present invention preferably has a melting point of 100 ° C. or higher, more preferably 110 ° C. or higher. A synthetic resin film having a melting point of less than 100 ° C. may cause the sheet itself to be melted or deformed by heat when the window frame sash becomes high temperature due to solar radiation.
Materials that can be used include polyolefin resins such as polypropylene, high density polyethylene, low density polyethylene, and linear low density polyethylene, vinyl acetate resins such as ethylene acetate copolymer, polyvinyl alcohol ethylene vinyl acetate copolymer, ethylene vinyl acetate copolymer, and polyester. And polyurethane resins such as polyethylene, polyether and polycarbonate, and polyester resins such as polyethylene terephthalate and polybutylene terephthalate. Among these resins, linear low density polyethylene is preferably used in terms of melting point, flexibility, tear strength, and weather resistance.

  The thickness of one synthetic resin film is preferably 50 to 300 μm, and more preferably 80 to 250 μm. If the thickness is less than 50 μm, the sash frame hits the sheet when the sash frame hits it, and the film may be torn and torn, making it difficult to prevent waterproofing and preventing the seepage from the swelling layer. There is a possibility that the tear strength of the material cannot be maintained. Moreover, when it becomes thicker than 300 micrometers, while the waterproof sheet for building foundations becomes hard, it is difficult to wind, and furthermore, since the weight per unit area becomes heavy, it may be difficult to handle.

  In addition, the surface of the synthetic resin film used for the surface layer can be embossed or the like for the purpose of imparting anti-slip properties. The unevenness of the film surface due to embossing or the like is preferably 20 to 200 μm, more preferably 50 to 100 μm. If the unevenness on the film surface is less than 20 μm, the slip resistance may not be obtained. On the other hand, if the difference in film surface unevenness is larger than 200 μm, the thickness of the product increases, the winding diameter becomes thick, and the handling may be difficult. Examples of the film surface pattern include round dots, diamond-shaped dots, and turtle shell-shaped dots. The shape, the number of irregularities, and the contact area are not particularly limited as long as they have anti-slip properties.

  Moreover, 5-60 micrometers is preferable and, as for the thickness of the other synthetic resin film, More preferably, it is 20-50 micrometers. If the thickness is less than 5 μm, the film may be damaged due to abrasion with the laying base, and the water-absorbing polymer resin may ooze out and the waterproof property may be lost. If it is thicker than 60 μm, the strength and the like are sufficient, but the weight increases, which may make it difficult to handle, and is not economical.

The synthetic resin film used for the back layer is constructed for the purpose of preventing the seepage of the resin when the water-absorbing polymer resin is gelled at the time of water absorption as described above, and further reinforcing the entire waterproof sheet for building foundations. It is what you are doing.

Moreover, it is preferable that the static friction coefficient (based on the measuring method of JIS K7125 8.1) of two layers of synthetic resin films shall be 0.2 or more, More preferably, it is 0.3 or more. When the coefficient of static friction is less than 0.2, when the sheet is wound in a roll shape, winding slippage may occur due to slippage, which may hinder workability in carrying and construction.
In order to obtain a coefficient of static friction between the synthetic resin films of 0.2 or more, it is preferable that the uneven surface area of the film surface layer is 90% or more of the area of each of the two layers. If the area of the convex portion is smaller than 90%, the contact area between the two layers is reduced, and the static friction coefficient may be less than 0.2. Moreover, when using the synthetic resin whose static friction coefficient between synthetic resin films is less than 0.2, a static friction coefficient can be 0.2 or more by making the synthetic resin film surface uneven | corrugated by embossing. There is also a method of forming an unevenness by applying a rubber-based resin, but the rubber-based resin changes in quality at a high temperature, and there is a possibility that the sheet cannot be separated at the time of disassembly due to close contact with the film.

The glass transition temperature of the synthetic resin used for the two-layer synthetic resin film is preferably 0 ° C. or lower. When the glass transition temperature is higher than 0 ° C., the sheet flexibility is lost when icing occurs on the sheet surface, and there is a risk that the sheet may crack due to bending during construction at low temperatures. Specific examples of the synthetic resin having a glass transition temperature of 0 ° C. or lower include polybutadiene and linear low density polyethylene.

The nonwoven fabric used in the present invention is preferably a nonwoven fabric composed of long fibers having no change in appearance at a temperature of 100 ° C., a dimensional change of 1% or less, and a tensile strength of 100 N / 5 cm or more. If the tensile strength is less than 100 N / 5 cm, the product may be damaged by an external force when constructing the product. Such non-woven fabrics are non-woven fabrics in which long filament filaments made of synthetic resin such as polyester, polyamide, polyacryl, and polyolefin are deposited in high density and non-directionally, and are spun, drawn, opened, and bonded. The long fibers are randomly deposited and bonded by the direct spinning method in which the above steps are continuously performed. Specifically, a synthetic resin that can be spun is put into an extruder to be in a molten state, and a non-woven fabric by a spunbond method in which a fiber extruded from a spinning nozzle is drawn by a roller method or an air jet method, a molten resin A melt blown nonwoven fabric that is sprayed from a spinning nozzle together with a high-pressure gas stream into a stretched fiber, or a solution in which a spinnable synthetic resin is dissolved in a solvent at high temperature and high pressure is discharged into the atmosphere through the spinning nozzle to vaporize the solvent. And non-woven fabrics produced by flash spinning, which are converted into fibers.
The basis weight of the nonwoven fabric is preferably 30 to 300 g / m ² , more preferably 40 to 100 g / m ² . If it is smaller than 30 g / m ^2, the strength of the entire sheet may not be sufficiently secured. If it is larger than 300 g / m ² , the nonwoven fabric is thick and heavy, so that the workability during carrying and construction deteriorates.
The thickness of the nonwoven fabric is preferably 0.2 to 1.5 mm, more preferably 0.4 to 0.8 mm. If the thickness is less than 0.2 mm, the non-woven fabric will be lost and the workability may be deteriorated. On the other hand, if it is larger than 1.5 mm, the handleability becomes worse, for example, the winding diameter increases.
Moreover, it is preferable that this nonwoven fabric is formed with the synthetic fiber whose melting | fusing point is 100 degreeC or more, More preferably, it is 110 degreeC or more. Nonwoven fabrics made of natural fibers lose strength when they soak in water, and the sheet itself may be damaged. In addition, nonwoven fabrics made of synthetic fibers with a melting point of less than 100 ° C have a window frame sash. When the temperature becomes higher, the sheet itself may be dissolved or deformed by heat.

The water-absorbing polymer resin used in the present invention includes cellulose / acrylonitrile polymer, starch / acrylonitrile polymer, acrylic acid / vinyl alcohol copolymer, sodium acrylate polymer, sodium acrylate / acrylamide polymer, polyethylene oxide modified product. , Isobutylene / maleic anhydride copolymer, etc., but synthetic water-absorbing polymer resin systems such as polyacrylic acid copolymer and vinyl alcohol copolymer are preferred from the viewpoint of heat stability and water expansion coefficient. Used. A combination of these resins can also be used.
The water absorption expansion ratio of the water-absorbing polymer resin needs to be larger than 200 times, more preferably 400 times or more. If the water absorption expansion ratio is 200 times or less, it is difficult to completely fill the minute space around the nail even if moisture entering from the periphery of the nail is absorbed.
In the present invention, the water absorption expansion ratio is measured by adding excess distilled water to a dried water-absorbing polymer resin and allowing it to stand at 20 ° C. for 24 hours, and then obtaining the water absorption from the weight change before and after water absorption. The water absorption expansion ratio was calculated.
[Formula 1] Water absorption expansion ratio = Amount of water absorption / Dry weight These water-absorbing polymer resins are bonded to the front or back surface of the nonwoven fabric using a binder in a fine powder state, or impregnated in the nonwoven fabric layer. Is preferably as small as possible and is preferably 100 μm or less. If it is larger than 100 μm, it will be difficult to uniformly apply to the nonwoven fabric, and it will be difficult to obtain a stable water-stopping property. As the binder to be used, vinyl resin, urethane resin, silicon resin, acrylic resin, epoxy resin, ester resin, etc. can be used. Among them, acrylic resin is used from the viewpoint of good handleability during processing and cost. System resins are preferably used. Examples of the method for applying the water-absorbing polymer resin include a coating method, a gravure method, a screen printing method, an impregnation method, and a spray method.
The application amount of the water-absorbing polymer resin is 5 to 40 g / ^{m 2} in a dry state, preferably 10 to 30 g / ^{m 2.} When the applied amount is less than 5 g / m ^2, sufficient there is a possibility can not be maintained waterstop since it is not possible filling the gap nail holes, also be imparted more than 40 g / m ^2, expanded resin nail hole As a result, it is difficult to improve the performance and is wasted in terms of cost.
Moreover, the occupation area with respect to the nonwoven fabric of the swelling layer which consists of a water absorbing polymer resin is 40 to 100%, Preferably it is 50 to 100%. If the occupied area is less than 40%, the area where the water-absorbing polymer resin is not applied becomes wider, and there is a portion where the water-absorbing polymer resin does not exist around the nail in the nail hole, thereby exhibiting water-stopping performance. There is a possibility that it cannot be done.

Examples of the method for sandwiching the nonwoven fabric between the two layers of synthetic resin films include a method in which the synthetic resin is melt laminated to the nonwoven fabric by extrusion lamination. The film material to be used is not particularly limited as long as it is a resin that can be extruded and laminated with a T-die or the like and has good adhesion to the nonwoven fabric. As preferred resins, synthetic resins such as polyolefin, polyvinyl acetate, polyester, polyurethane, and polystyrene are easily melt-extruded, have good adhesiveness, and are economically preferable. Among these, an appropriate material can be selected in consideration of the kind of the nonwoven material to be used and the adhesiveness with the resin film.
In addition, when using a synthetic resin film that has already been formed into a film, a method of heat lamination with a resin that can be extruded and laminated with a T-die that has good adhesion to the nonwoven fabric is used. Can be appropriately selected from the synthetic resins listed above. The adhesive used is not particularly limited as long as a solvent system or an emulsion system is selected depending on the method and purpose.
As other methods, methods such as ordinary dry lamination and wet lamination can be used, but the melt lamination method is preferably used from the economical viewpoint.
Further, the ratio of the adhesion area between the two-layer synthetic resin film and the nonwoven fabric including the swelling layer is preferably 30% or more. If the adhesion area is lower than 30%, when the water-absorbing polymer resin absorbs moisture and swells, sufficient adhesion strength may not be obtained, and the synthetic resin film and the nonwoven fabric may peel off, causing resin flow, water leakage, There is a risk of bleeding.

The total weight of the waterproof sheet for building foundations of the present invention is preferably 100 to 600 g / m ² , more preferably 200 to 400 g / m ² . If it is lighter than 100 g / m ^{2, the} sheet will be easily damaged by the wind during construction and the workability may be deteriorated. If it is heavier than 600 g / m ² , it will be difficult to carry high places. There is a risk that it will be worse.
Moreover, the total thickness of the waterproof sheet for building foundations of the present invention is preferably 200 to 1000 μm. If the total thickness is less than 200 μm, sufficient strength as a waterproof sheet may not be obtained. Moreover, when larger than 1000 micrometers, a waterproof sheet becomes difficult to bend and there exists a possibility that a workability may worsen.

  In addition, the strength of the waterproof sheet for building foundations of the present invention is preferably 20 N or more for both the length (length direction) and the width (width direction of the roll) in the tear strength measurement based on JIS L 1096. If the tear strength is less than 20N, the nail hole portion (surrounding) strength cannot be maintained when walking on the architectural foundation tarpaulin after nailing the building construction tarpaulin. There is a risk of water leakage from this part.

  The weight of each of the nonwoven fabric and the synthetic resin film constituting the waterproof sheet for building foundations in the present invention is appropriately selected so that the total weight and total strength of the waterproof sheet for building foundations fall within the above prescribed range, and 100 ° C. By appropriately combining the non-woven fabric and resin film having the above melting points and a water-absorbing polymer resin excellent in thermal stability, a waterproof sheet for building foundations excellent in durability that hardly resists thermal degradation can be obtained.

〔Example〕
EXAMPLES Hereinafter, although this invention is demonstrated in more detail based on an Example, it does not specifically limit to an Example. In addition, each characteristic value in an Example is measured with the following method.

(Nail hole water resistance)
In an environment of room temperature (20 to 25 ° C.), a filter paper is sandwiched between a 12 mm thick plywood and the produced waterproof sheet (sample), and a spelling needle (shoulder width of 12 mm, foot) of No. 3 U stapler specified by JIS S6030 from the surface of the sample. 10mm long, T3-10MB manufactured by MAX). Thereafter, based on JIS A 5430 10.6 (permeability test), water was poured into a tube upright on the sample surface to a height of 50 mm, and the water leakage state to the filter paper after being left for 24 hours was evaluated as follows.
○: Water leakage trace area on the filter paper is 1 cm ² or less ×: Water leakage trace area on the filter paper is larger than 1 cm ²

(Nail hole water stop and durability)
JIS A1415 (Table 4) solar radiation exposure test was conducted using the surface of the sheet construction as the irradiation surface, and then a sheet subjected to heat treatment at 80 ° C. ± 2 ° C. for 14 weeks according to JIS K7271, A water-stopping test was conducted, and the water leakage state to the filter paper after being left for 24 hours was evaluated as follows.
○: Water leakage trace area on the filter paper is 1 cm ² or less ×: Water leakage trace area on the filter paper is larger than 1 cm ²

(Durable tear strength)
A JIS A1415 (Table 4) solar radiation accelerated exposure test was conducted using the sheet construction surface as the irradiated surface, and then a sheet subjected to heat treatment at 80 ° C. ± 2 ° C. for 14 weeks in accordance with JIS K7271, using JIS L1096 as a test specimen. It evaluated below by the retention with respect to the tear strength in (8.15.2 A-2 method) and the tear strength before solar radiation acceleration | stimulation exposure.
○: Retention rate of tear strength of 15 N or more and 50% or more before promotion of solar radiation ×: Retention rate of tear strength of less than 15 N or less than 50% before promotion of solar radiation

[Stability over time]
JIS A1415 (Table 4) is subjected to solar radiation accelerated exposure test using the sheet construction surface as the irradiated surface, and then the dimensional change (shrinkage rate) after heat treatment at 80 ° C ± 2 ° C for 14 weeks according to JIS K7271 did.
○: Shrinkage rate is 1% or less ×: Shrinkage rate is greater than 1%

[Rolling slip prevention]
The static friction coefficient between two layers of sheets was measured based on JIS K7125 8.1 and evaluated as follows.
○: Winding deviation hardly occurs when the coefficient of static friction is 0.2 or more.
×: Winding deviation is likely to occur smaller than the static friction coefficient 0.2.

〔Workability〕
Judged by ease of carrying as follows.
○: One product with a weight of less than 600 g / m ² (300 mm width and 20 m roll) can be easily carried with one hand.
X: It is difficult to carry one product (20 mm roll with 300 mm width) weighing 600 g / m ² or more with one hand.

[Example 1]
Gravure a water-absorbing polymer resin (manufactured by Sanyo Kasei Kogyo Co., Ltd.) made of starch-polyacrylate with a water absorption expansion ratio of 600 times on a polyester spunbond nonwoven fabric (manufactured by Toyobo Co., Ltd.) having a basis weight of 60 g / m ^2. It applied so that 20 g / m < ² > might adhere to 80% of this nonwoven fabric area with a roll coater as solid content. While the molten low-density polyethylene having a weight of 25 g / m ² is extruded from a T-die onto the surface of the nonwoven fabric coated with the water-absorbing polymer resin, the linear low-density has a thickness of 100 μm and a density of 0.95 g / cm ^3. By heat laminating a polyethylene film (made by Sakai Chemical Industry Co., Ltd.) with a pressure roll, and extruding low-density polyethylene to a thickness of 50 μm from the T-die on the opposite side of the heat-laminated film, and pressing with a pressure roll. A waterproof sheet for architectural foundations having a target thickness of 350 μm and a weight of 250 g / m ² was obtained. The static friction coefficient between the synthetic resin film of the surface layer and back layer of the obtained waterproof sheet for building foundations was 0.3, and the linear low density polyethylene film surface was used as the surface layer. The evaluation results are shown in Table 1.

[Example 2]
To a polypropylene spunbonded nonwoven fabric (made by Idemitsu Unitech Co., Ltd.) having a weight of 100 g / m ² , a water-absorbing polymer resin (Aqua reserve GP made by Nippon Synthetic Chemical Co., Ltd.) made of crosslinked polyvinyl alcohol having a water absorption expansion ratio of 400 times is used. A gravure roll coater was applied to 50% of the nonwoven fabric area so as to adhere 30 g / m ² as a solid content. Low-density polyethylene film with a thickness of 350 μm and a density of 0.95 g / cm ³ (Sakai Chemical Industry Co., Ltd.) (Made by company) is adhered by dry laminating method, and a polyethylene vinyl acetate film having a thickness of 50 μm is adhered by dry laminating method to the surface not coated with water-absorbing polymer resin, and the target is 650 μm in weight and 280 g / weight. A waterproof sheet for architectural foundation m ² was obtained. The static friction coefficient between the synthetic resin film of the surface layer and back layer of the obtained waterproof sheet for building foundations was 0.5, and the low density polyethylene film surface was used as the surface layer. The evaluation results are shown in Table 1.

[Comparative Example 1]
A water-absorbing polymer resin having a water expansion coefficient of 200 times (Arakawa Chemical Industries, Ltd. polyacrylic acid-based water-absorbing polymer resin Arasop) is attached to 90% of the nonwoven fabric area as a solid content of 40 g / m ^2. A waterproof sheet for building foundations having a thickness of 350 μm and a weight of 250 g / m ² was obtained in the same manner as in Example 1 except that the coating was applied. The coefficient of static friction between the synthetic resin film of the surface layer and the back layer of the obtained waterproof sheet for building foundations is 0.3, and Table 1 shows the evaluation results using the linear low density polyethylene film surface as the surface layer.

[Comparative Example 2]
A water-absorbing polymer resin having a water absorption expansion ratio of 600 times (fat starch-polyacrylate water-absorbing polymer resin manufactured by Sanyo Chemical Industries, Ltd.) is attached to 35% of the nonwoven fabric area as a solid content of 40 g / m ^2. A waterproof sheet for building foundations having a thickness of 650 μm and a weight of 280 g / m ² was obtained in the same manner as in Example 1 except that the coating was applied to the base material. The coefficient of static friction between the synthetic resin film of the surface layer and the back layer of the obtained waterproof sheet for building foundations is 0.3, and Table 1 shows the evaluation results using the linear low density polyethylene film surface as the surface layer.

[Comparative Example 3]
The rubber-modified asphalt sheet was laminated with the asphalt-impregnated non-woven fabric and the asphalt-impregnated paper sandwiched to obtain a waterproof sheet for building foundation having a thickness of 850 μm and a weight of 750 g / m ² . The evaluation results are shown in Table 1.

[Comparative Example 4]
A polypropylene nonwoven fabric and a polyethylene sheet were laminated to obtain a waterproof sheet for building foundations having a thickness of 300 μm and a weight of 220 g / m ² . The evaluation results are shown in Table 1.

It is the schematic example which shows the cross section of the waterproof sheet for building foundations of this invention.

Explanation of symbols

1. 1. Synthetic resin film on the surface layer Swelling layer (water-absorbing polymer resin)
3. 3. Nonwoven fabric Synthetic resin film for the back layer

Claims (6)

A multilayer structure in which a non-woven fabric having a swelling layer made of a water-absorbing polymer resin is sandwiched between two synthetic resin films, and the water-absorbing polymer having a water absorption expansion ratio larger than 200 times as the swelling layer A waterproof sheet for building foundations, wherein the resin is formed in an amount of 5 to 40 g / m ² and the area occupied by the swelling layer with respect to the nonwoven fabric is 40 to 100%. The waterproof sheet for architectural foundations according to claim 1, wherein the non-woven fabric and the synthetic resin film have an adhesion area ratio of 30 to 100%.   The thickness of one synthetic resin film is 50 to 300 μm, the thickness of the other synthetic resin film is 5 to 60 μm, and the coefficient of static friction between the two layers of film is 0.2 or more. The waterproof sheet for building foundations according to claim 1 or 2. Waterproof sheet for building foundation according to claim 1 nonwoven fabric of basis weight are formed by synthetic fibers 30~300g / m ^2.   The waterproof sheet for building foundations according to any one of claims 1 to 4, wherein at least one of the two-layer synthetic resin films contains a linear low-density polyethylene resin. Fixing to plywood with a No. 3 U stapler spelling needle specified in JIS S6030, and water to the plywood when placed in a tube to a height of 50 mm and allowed to stand for 24 hours according to JIS A 5430 10.6 (water permeability test) The waterproof sheet for building foundations according to claim 1, wherein a leak area does not exceed 1 cm ² .

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