JPH07108562B2 - Tarpaulin that can be heat-sealed - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-sealable waterproof sheet, and more particularly to a heat-sealable waterproof sheet having excellent stain resistance and weather resistance.

[0002]

2. Description of the Related Art Conventionally, for example, a flexible sheet having a soft vinyl chloride (PVC) resin layer on one or both sides of a fibrous base fabric has been used for a large tent such as an air dome.
Such a sheet has advantages peculiar to PVC in terms of processability, economical efficiency, flameproofness, etc. On the other hand, since such a tent is exposed to the outdoors for a long time,
Even if the stabilizers to be blended are thoroughly examined, the resin gradually decomposes over the years, and the plasticizer migrates to the surface to gradually make the surface sticky and dust on the surface. It had a serious defect such as adherence and contamination.

As a countermeasure against this, an acrylic resin film layer is formed on the upper surface of the PVC layer to cover the drawbacks of the conventional laminated product having only the PVC layer and obtain a predetermined effect. However, depending on the condition of use of the laminated product, cracking may occur in the acrylic resin film layer under conditions such as strong rubbing, resulting in a marked reduction in the useful life of the laminated product. Has not yet reached.

However, the surface of such a laminated sheet is constituted by sticking a film made of vinylidene fluoride resin / acrylic resin / PVC resin, and the vinylidene fluoride resin layer is used as the outer surface, A method for improving weather resistance and stain resistance was found. When such a waterproof sheet is sewn with a sewing machine, water leaks from the seams, and because the sewing efficiency of the sewing machine is poor, high-frequency or hot air is often used to perform heat-sealing. However, even if it is attempted to join the laminated sheet having the vinylidene fluoride resin layer as the outer surface by using the heat-sealing method, the vinylidene fluoride resin layer does not adhere, and therefore this sheet is also required to be further improved. By the way.

[0005]

DISCLOSURE OF THE INVENTION The present invention is a very useful waterproof sheet having excellent antifouling property and weather resistance, capable of being heat-sealed and having a durable antifouling property. Is to provide.

[0006]

According to the present invention, there is provided a heat-sealable waterproof sheet, which comprises natural rubber, synthetic rubber or A waterproof sheet having a waterproof layer made of synthetic resin is characterized in that a vinylidene fluoride resin layer is formed as an outermost layer on an upper surface thereof and an acrylic resin layer is formed on an entire outermost layer of the lower surface thereof.

An example of the waterproof sheet of the present invention will be described with reference to FIG. In the embodiment of the waterproof sheet of the present invention shown in FIG. 1, waterproof layers 2, 2 ′ made of natural rubber, synthetic rubber or synthetic resin are formed on both front and back surfaces of a fibrous base cloth 1, and the waterproof layer 2 on the side of the waterproof layer 2 is A vinylidene fluoride resin layer 3 is formed on the uppermost outermost layer. If necessary, between these waterproof layer 2 and the vinylidene fluoride resin layer 3, and contiguous with the layers Polyurethane resin layer or cyanoethylated ethylene - vinyl alcohol copolymer layer may be formed . On the other hand, an acrylic resin layer 4 is formed on the entire outer surface of the lowermost outermost layer on the waterproof layer 2 ′ side so as to be continuous with the waterproof layer 2 ′.

In another aspect of the waterproof sheet of the present invention,
The above-described and a waterproof layer 2 is omitted Polyurethane resin layer or cyanoethylated ethylene - vinyl alcohol copolymer layer
Formed directly on the surface of the fibrous base cloth 1 , or the waterproof layer 2 '
Is omitted and the acrylic resin layer, polyurethane resin layer or
Anoethylated ethylene-vinyl alcohol copolymer layer
It can be directly formed on the back surface of the fibrous base fabric 1 to form a waterproof layer. Alternatively, the waterproof layer 2 and the port Riureta <br/> down resin layer or cyanoethylated ethylene - can also be formed of any other layer between the vinyl alcohol copolymer layer and the waterproof layer 2 'and acrylic Another arbitrary layer may be formed between the resin layer 4 and the resin layer 4. Further, the waterproof layer 2'may be omitted, or the waterproof layer 2'may be omitted and other arbitrary layer may be formed instead.

That is, the essential requirements for the waterproof sheet of the present invention are that it has a fibrous base cloth as an inner layer, has a waterproof layer, and has a vinylidene fluoride resin layer as an outermost layer on the upper surface. , And that the acrylic resin layer is formed on the entire lower surface of the outermost layer. Hereinafter, the present invention will be described more specifically. The fibrous base fabric used in the waterproof sheet of the present invention includes natural fibers such as cotton and hemp, inorganic fibers such as glass fiber, carbon fiber and metal fiber, recycled fibers such as viscose rayon and cupra. , Semi-synthetic fibers such as di- and tri-acetate fibers, and synthetic fibers such as polyamide (nylon 6, nylon 66 etc.) fibers, polyester (polyethylene terephthalate etc.) fibers, aromatic polyamide fibers, acrylic fibers, poly It is composed of at least one selected from vinyl chloride fiber, polyolefin fiber and the like. The fibers in the base fabric may have any shape such as short fiber spun yarn, long fiber yarn, split yarn, tape yarn, etc., and the base fabric may be a woven fabric, a knitted fabric, a non-woven fabric or a composite thereof. It may be any of cloth. Generally, the fibers used in the waterproof sheet of the present invention are preferably polyester fibers, which are preferably in the form of long fibers (filaments), and preferably form a plain woven fabric. Further, a woven fabric formed by stacking warp yarns and weft yarns arranged in parallel so as to intersect each other and pressing them with a twine yarn is particularly preferable. The fibrous base cloth is
It is useful for maintaining the mechanical strength of the obtained waterproof sheet at a high level.

In the present invention, a waterproof layer is formed by forming a waterproof layer on the front surface or both front and back surfaces of the fibrous base cloth, and the material of this waterproof layer is natural rubber, neoprene rubber, chloroprene rubber, silicone. Rubber, Hypalon and other synthetic rubbers, PVC resin, ethylene-vinyl acetate copolymer (EVA) resin, acrylic resin (upper surface
This resin is placed just below the outermost vinylidene fluoride resin layer.
( Excluding the case where the waterproof layer is formed) , a silicone resin, a urethane resin, a polyethylene (PE) resin, a polypropylene (PP) resin, a polyester resin, a fluororesin and other synthetic resins can be used. The waterproof layer made of such a material has a thickness sufficient to impart desired waterproofness and flame retardancy and mechanical strength to the resulting waterproof sheet,
For example, 0.05 mm or more, preferably 0.05 to 2.
It has a thickness of 0 mm.

These waterproof layers are formed by a known method, for example, a method such as topping, calendering, coating, dipping, etc., using the rubber or resin film, solution, paste or straight as described above.
It can be formed on a fibrous base fabric. These rubbers or resins may contain a plasticizer, a stabilizer, a colorant, an ultraviolet absorber, and other function-imparting agents.

On the upper surface of the waterproof sheet according to the present invention, a vinylidene fluoride resin layer is formed as the outermost layer. As the vinylidene fluoride resin, in addition to vinylidene fluoride homopolymer, vinylidene fluoride is contained in an amount of 70 mol% or more, and a monomer copolymerizable therewith, for example, tetrafluoroethylene, trifluoroethylene, fluorine. A copolymer obtained by copolymerizing at least one monomer selected from vinyl chloride, trifluoroethylene chloride, fluorochlorovinylidene, and vinylidene hexafluoride is used. In some cases, a mixture containing other resins having good compatibility with these homopolymers or copolymers can be used. Examples of the resin having good compatibility with such vinylidene fluoride resin include, for example, a polymer or copolymer mainly composed of methyl methacrylate or methyl acrylate, a polyurethane resin or a cyanoethylated ethylene-vinyl alcohol copolymer. is there. However, it is preferable that these other resin components be within 30 PHR of the constituent resin amount.

If necessary, the vinylidene fluoride resin layer may contain a stabilizer, a processing aid such as a lubricant, and UVA. In particular, the addition of UVA is
Preferred meanings to prevent light degradation of these resins in the vicinity of the junction surface of the vinyl alcohol copolymer layer - optionally the bottom are formed in Lupo polyurethane resin layer or cyanoethylated ethylene. However, the amount of UVA that is compatible with the vinylidene fluoride resin in a uniform phase is not so large, and is generally 3% or less. In addition, since the vinylidene fluoride resin layer is generally extremely thin, it cannot be expected that UVA of this layer completely protects the waterproof layer.

However, since the vinylidene fluoride resin layer protects only the surface layer of the sheet, 0.3 to 10
It preferably has a thickness of μm, more preferably 1 to 5 μm. In the present invention, the upper surface Polyurethane resin layer immediately below the outermost layer of vinylidene fluoride resin layer or cyanoethylated ethylene - preferably forms a vinyl alcohol copolymer layer, the thickness of these layers, preferably The thickness is preferably 0.5 to 30 μm, more preferably 2 to 20 μm, and is generally larger than the thickness of the vinylidene fluoride resin layer.

The acrylic resin constituting the acrylic resin layer useful in the present invention is mainly composed of a polymer or copolymer having a C _{1 to} C ₄ alcohol ester of acrylic acid or methacrylic acid as a main constituent monomer. Resins are preferred. The main constituent monomers of such an acrylic ester resin are specifically methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate, butyl acrylate and butyl methacrylate, and particularly methyl acrylate and methyl acrylate. Methacrylate is preferred. Examples of comonomers copolymerized with these main constituent monomers include esters of C _{1 to} C ₁₂ alcohols of acrylic acid or methacrylic acid, vinyl fluoride, vinylidene fluoride, vinyl chloride, vinylidene chloride, vinyl acetate, styrene. , Acrylonitrile, methacrylonitrile and butadiene. These copolymers are not limited to random copolymers and may be graft copolymers. For example,
It is also possible to use a polymer obtained by adding vinylidene fluoride to a methyl methacrylate polymer and then graft-polymerizing this. An acrylate containing an amino group, an imino group, an ethyleneimine residue, or an alkylenediamine residue can be used, but particularly preferable results are obtained when an acrylate containing an aziridinyl group is used.

The acrylic resin layer may contain a small amount of another resin having a good compatibility with the acrylic resin. In particular, PVC resin, polyurethane resin, and vinylidene fluoride resin are all useful because they have good compatibility with acrylic resin. The same applies to the cyanoethylated ethylene-vinyl alcohol copolymer. Further, an ultraviolet absorber (UVA) may be added to these resin layers in order to impart durable weather resistance. It is preferable that the compounding amount of UVA is determined so that the incident ultraviolet light can be blocked by about 50% or more. This UV blocking amount depends on the concentration of UVA in these resin layers containing UVA and the thickness of this layer.
If the concentration is too low, it is necessary to increase the thickness of these resin layers and therefore the UVA of these resin layers.
The concentration is preferably 0.3% or more, more preferably 1.0
Should be at least%. However, UVA in this resin layer
If the concentration is too high, bleeding may occur at the interface with the vinylidene fluoride resin layer forming the uppermost outermost layer and the adhesive strength with this layer may be reduced, such being undesirable. Of course U
The compatibility of these resins and vinylidene fluoride resins varies depending on the type of VA, so the upper limit of the concentration is different, but even benzotriazole-based UVAs that have a relatively high affinity for vinylidene fluoride resins have 30 PHR.
If it exceeds, it becomes easy to peel off at the interface of both layers, so 3
It is preferable to keep it at about 0 PHR or less. As the UVA, not only benzotriazole-based UVA, but also benzophenone-based, salicylate-based UVA, or those obtained by copolymerizing these with other resins is not particularly limited. .

[0017] In manufacturing a waterproof sheet of the present invention, for example, a sheet formed a waterproof layer on the surface or both surfaces of the fibrous base fabric is first prepared, then the depot polyurethane resin or cyanoethylated ethylene - vinyl alcohol with or without coating a copolymer and may be formed by coating a vinylidene fluoride resin, also thereon separately manufactured polyvinylidene fluoride or polyvinylidene fluoride / polyurethane resins or cyanoethylated the surface alternatively A laminated film of an ethylene-vinyl alcohol copolymer may be attached. This vinylidene fluoride resin or vinylidene fluoride resin / polyurethane resin laminated film is thin,
If a problem in workability arises, such as PVC film having a thickness of 30 to 50 [mu] m, polyvinylidene fluoride / Polyurethane resins or cyanoethylated ethylene as a support waterproof substrate if - vinyl alcohol copolymer It is also possible to make a laminated film made of / PVC resin or the like and attach it to the above sheet. Although the production of such a laminated film is not particularly limited,
The resin of each layer is compositely flowed from the composite T die or the composite cylindrical die, and the flat sheet or the cylinder is coextruded,
It is desirable from the standpoints of adhesion between layers and productivity that it is carried out by a conventional method and then heat treatment if necessary.

In the waterproof sheet of the present invention, the thickness and material of the acrylic resin layer forming the outermost layer on the lower surface can be selected in substantially the same manner as described above for these resin layers on the upper surface. In this case, the lower surface is less likely to be exposed to direct sunlight, and thus UVA need not be compounded as much as the upper surface, and compounding can be omitted. Further, this layer can be formed not only by sticking the film as described above but also by coating. Further, other copolymers and other processing agents can be added to this layer as long as the adhesion is not impaired. Further, for the purpose of promoting adhesiveness with the waterproof layer, for example, when a PVC waterproof layer is formed, measures such as mixing PVC with this layer can be taken.

The polyurethane resin used in the present invention is freely selected with respect to its use form, and includes a plasticizer, a stabilizer,
Colorants, lubricants and other various additives can be freely added within the known range. An example of the polyurethane resin useful in the present invention, particularly the thermoplastic polyurethane elastomer resin, is shown below.

As the polyurethane elastomer, one obtained by reacting an organic polyisocyanate with a polymer polyol and, if necessary, a chain extender is used. As the organic polyisocyanate, aliphatic, alicyclic or aromatic polyisocyanate, for example, hexamethylene diisocyanate, lysine diisocyanate, cyclohexylene diisocyanate, dicyclohexylmethane diisocyanate, isophorone diisocyanate, tolylene diisocyanate, xylylene diisocyanate, phenylene diisocyanate, diphenylmethane. Diisocyanate (MDI), biphenylene diisocyanate,
Examples include naphthylene diisocyanate. Among these, MDI or an organic diisocyanate mainly containing MDI is preferable.

The polymer polyols include polyether polyols, polyester polyols, polyether ester polyols, polymer polyols and two of these.
Mention may be made of mixtures of more than one species. Polyether polyols include alkylene oxides (ethylene oxide, propylene oxide, butylene oxide, etc.),
Those obtained by polymerizing or copolymerizing (block or random) a heterocyclic ether (tetrahydrofuran etc.), for example, polyethylene glycol, polypropylene glycol, polyethylene-propylene (block or random) glycol, polytetramethylene ether glycol, polyhexa Mention may be made of methylene ether glycol, polyoctamethylene ether glycol and mixtures of two or more thereof. As the polyester polyol, dicarboxylic acid (adipic acid, succinic acid,
Sebacic acid, glutaric acid, maleic acid, fumaric acid, phthalic acid, etc.) and glycols (ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, 1,8-octamethylenediol, neopentyl glycol) , Bishydroxymethylcyclohexane, bishydroxyethylbenzene, alkyl dialkanolamine, etc.), such as polyethylene adipate, polybutylene adipate, polyhexamethylene adipate, polyethylene / propylene adipate: polylactone diol such as polyadduct Caprolactone diol: and mixtures of two or more thereof. As the polyether ester polyol, an ether group-containing diol (the above-mentioned polyether diol, diethylene glycol, triethylene glycol, dipropylene glycol, etc.) or a mixture thereof with another glycol is used as the above-mentioned dicarboxylic acid or dicarboxylic acid anhydride (anhydrous phthalate). Acid, maleic anhydride, etc.)
And those obtained by reacting with alkylene oxides, such as poly (polytetramethylene ether) adipate.

Further, as the polymer polyol, a high molecular weight polyol (the above-mentioned polyether polyol, polyester polyol, and / or polyether ester polyol) or a mixture thereof with a medium to low molecular weight diol is used. Examples thereof include those obtained by polymerizing acrylonitrile and styrene).
Average molecular weight of polymer polyol (by hydroxyl value titration)
Is usually 500 to 5000, preferably 700 to 400
0, particularly preferably 2000 to 3500.

As the chain extender, a low molecular weight polyol having a molecular weight of less than 500, for example, ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-
Hexanediol, diethylene glycol, triethylene glycol, thiodiglycol (thiodiethanol, etc.); polyamines, for example, ethylenediamine, propylenediamine, butylenediamine, hexamethylenediamine and other aliphatic diamines, piperazine, 1,4-diaminopiperazine, 1, Alicyclic polyamines such as 3-cyclohexylenediamine and dicyclohexylmethanediamine, aromatic polyamines such as diphenylmethanediamine, tolylenediamine and phenylenediamine, aromatic-aliphatic polyamines such as xylylenediamine, hydrazine and monoalkylhydrazine; alkanolamines , Ethanolamine, propanolamine; and mixtures of two or more thereof. Of these, preferred are low molecular weight diols (especially ethylene glycol).

However, the present invention is not limited to the above examples, and any other thermoplastic polyurethane resin can be used, and it is not limited to an ester type, an ether type, or the like, and is melted by heat and heat-pressed. Any material that can be welded (welded) can be used. The waterproof sheet thus obtained has excellent antifouling properties and weather resistance, and can be heat-sealed. That is, two sheets of this waterproof sheet are superposed, the uppermost outermost vinylidene fluoride resin layer and the lowermost outermost acrylic resin layer are brought into contact with each other, and fusion-bonded by ultrasonic heating, high-frequency heating or hot air. . When heat-sealing is performed in this manner, the adhesive strength is 0 to 3 kg / 3 cm for a sheet having no acrylic resin layer on the lower surface like a conventional waterproof sheet.
However, in the case of the waterproof sheet of the present invention, the adhesive strength is 6 to 10 kg / 3 cm, which is a preferable value exceeding about 5 kg / 3 cm which is practically required.
It may be possible to sandwich a film made of a resin which gives a preferable adhesive force at the time of such heat fusion sewing between two sheets to perform fusion bonding, but in this case, the adhesion force with the waterproof sheet is used. The adhesive strength is 3 ~
It is about 4 kg / 3 cm, and there is a difficulty in locating necessary parts during the fusion work, which is not preferable in terms of work. Also,
It is conceivable to partially form these resin layers on the lower surface instead of the continuous outermost layer on the lower surface, but in this case, work such as applying these resin layers at the time of sewing is troublesome and reduces workability. , Harm the working environment. Therefore, if these resin layers are formed as a continuous layer on the entire lower surface from the beginning like the waterproof sheet of the present invention, the waterproof sheet itself can be manufactured inexpensively and easily, and the sewing can be performed. It has the advantage that it can be performed wherever it is needed.

[0025]

[0026]

[0027]

[0028]

EXAMPLES The present invention will be further described below with reference to examples.
It Example 1 Vinylon fiber canvas having the following structure and density ( 20/3 × 20/4 ) / (45 × 38) basis weight of 360 g / m ² was used as a base fabric, and a hypalon resin waterproof layer and a silicone were used for the base fabric, respectively. A resin waterproof layer, an EVA resin waterproof layer, an acrylic resin waterproof layer and a urethane resin waterproof layer are formed, and an acrylic adhesive SC462 made by Sony Chemicals is used on the upper surface of the resin , and vinylidene fluoride resin (4 μm) / cyanoethylated ethylene is used. A film made of vinyl alcohol copolymer (10 μm)
Its cyanoethylated ethylene-vinyl alcohol copolymerization
It was attached with the body surface facing the waterproof sheet (I). Similarly, polyvinylidene fluoride (4 [mu] m) / polyurethane resin (10 [mu] m) made of a film that a polyurethane trees the
It was attached with the oil side facing the waterproof sheet (II). Further, an adhesive SC462 was applied to the back surface to a thickness of 5 μm to prepare a waterproof sheet (Group A) according to the present invention. Also,
For comparison, a sheet having no back side coated with an acrylic adhesive was prepared and used as a comparative sheet (group B).

For each of these sample sheets,
Stack the 3 cm edges as described in the text above,
The output of 2kW and the frequency of 40.68MHz are superimposed on the
A high frequency treatment was performed for 3 seconds by a frequency oscillator. As a result, the peel strength (kg / 3 cm) was as follows. Surface composition of waterproof layer A group B group Hypalon resin I 8.0 0.3 II 8.4 0.3 Silicone resin I 6.5 0 II 6.8 0.1 EVA resin I 8.1 0.9 II 8 .2 0.8 Acrylic resin I 9.0 8.9 II 9.0 9.2 Urethane resin I 8.6 8.4 II 8.8 9.4 In addition, the waterproof layer of the group B sheet is Acry
A sheet made of resin is an example of the present invention.

[0030]

As can be seen from the above, the waterproof sheet according to the present invention has a protective layer of vinylidene fluoride resin, and therefore, while maintaining excellent antifouling property, weather resistance and durability, the entire back surface is protected. Since the sheet has an acrylic resin layer, the sheet has an extremely great industrial value as a sheet that can be easily and inexpensively sewn.

[Brief description of drawings]

FIG. 1 is a cross-sectional view schematically showing an example of the waterproof sheet of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Fibrous base fabric 2, 2 '... Waterproof layer 3 ... Vinylidene fluoride resin layer 4 ... Acrylic resin layer

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location B29K 627: 12 633: 04

Claims (15)

[Claims] 1. A waterproof sheet having a fibrous base cloth having a waterproof layer made of natural rubber, synthetic rubber or synthetic resin on the front surface or both front and back surfaces thereof, wherein a vinylidene fluoride resin layer is formed as an outermost layer on the upper surface of the waterproof sheet. A heat-sealable waterproof sheet having an acrylic resin layer formed on the entire lower surface of the outermost layer. Wherein in said top surface, Polyurethane resin layer or cyanoethylated ethylene under the polyvinylidene fluoride layer - waterproof sheet according to claim 1, wherein the vinyl alcohol copolymer layer is formed. 3. The waterproof sheet according to claim 1, wherein an acrylic resin layer, a polyurethane resin layer or a cyanoethylated ethylene-vinyl alcohol copolymer layer is formed on the waterproof layer on the lower surface. 4. The waterproof sheet according to claim 1, wherein the acrylic resin layer forms the waterproof layer. 5. The waterproof sheet according to claim 1, wherein the waterproof layer has a thickness of 0.05 to 2.0 mm. 6. The resin according to claim 1, wherein the acrylic resin layer is made of a resin containing a polymer or a copolymer whose main monomer is an ester of a C _{1 to} C ₄ alcohol of acrylic acid or methacrylic acid. The waterproof sheet according to any one. 7. The acrylic resin is acrylic acid or
C of methacrylic acid ₁ ~ C _Four Alcohol ester and ac
C of phosphoric acid or methacrylic acid ₁ ~ C ₁₂ Alcoholic
Ester, vinyl fluoride, vinylidene fluoride, vinyl chloride
, Vinylidene chloride, vinyl acetate, styrene, acrylo
With nitrile, methacrylonitrile or butadiene
The waterproof sheet according to claim 6, which is a polymer. 8. The acrylic resin layer is made of PVC resin or poly
Contract containing urethane resin or vinylidene fluoride resin
The waterproof sheet according to claim 6 or 7. Wherein said acrylic resin phase, a polyurethane resin layer or cyanoethylated ethylene - claims 1-8 which vinyl alcohol copolymer layer has a thickness of 0.5~30μm
The waterproof sheet according to any one of 1. 10. The waterproof sheet according to claim 9 , wherein the layer has a thickness of 2 to 20 μm. 11. waterproof sheet according to any one of claims 1 to 10, wherein the vinylidene fluoride resins is a copolymer containing at least 70 mol% of vinylidene fluoride homopolymer or a vinylidene fluoride. 12. The vinylidene fluoride resin layer is fluorinated.
Compatibility of vinylidene resin and this vinylidene fluoride resin
10. The resin composition according to claim 9, wherein the resin composition is a mixed resin with another resin having good
Tarpaulin. 13. Compatibility with the vinylidene fluoride resin
Other resins with good
Polymer or copolymer mainly composed of acrylate,
Polyurethane resin or cyanoethylated ethylene-vinyl
The waterproof sheet according to claim 14, which is an alcohol polymer. 14. The vinylidene fluoride resin layer has a thickness of 0.3.
Waterproof sheet according to any one of claims 1 to 13 having a thickness of 10 .mu.m. 15. waterproof sheet according to claim 15, wherein the thickness of the vinylidene fluoride resin layer is 1 to 5 [mu] m.