JPS635267B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a waterproof sheet that can be sewn by heat sealing, particularly a waterproof sheet that has excellent stain resistance and weather resistance, and can be sewn by heat sealing, and a sewing method using the same. BACKGROUND ART Conventionally, flexible sheets having, for example, a fibrous base fabric and a soft vinyl chloride (PVC) resin layer on one or both sides have been used in large tents such as air domes. Such sheets have the unique advantages of PVC in terms of processability, economic efficiency, flame resistance, etc. However, on the other hand, since such tents are exposed outdoors for long periods of time, the stability of the compound is Even if the agent, etc. has been carefully examined, the resin will gradually decompose over many years, the plasticizer will migrate to the surface, and the surface will gradually become sticky, and dust will adhere to the surface. It had serious drawbacks such as contamination. As a countermeasure to this problem, an acrylic resin film layer is formed on the top surface of the PVC layer to cover the drawbacks of the conventional laminate product with only a PVC layer and to obtain the desired effect. However, depending on the usage conditions of the laminate, if the acrylic resin film layer is subjected to strong rubbing or other conditions, cracks may occur in the acrylic resin film layer, resulting in a significant shortening of the service life of the laminate, so this countermeasure is not sufficient. This has not yet been achieved. Therefore, one side of such a laminated sheet is constructed by pasting a film made of vinylidene fluoride resin/acrylic resin/PVC resin,
We have discovered a method to improve weather resistance and stain resistance by using a vinylidene fluoride resin layer on the outer surface. When such waterproof sheets are sewn using a sewing machine, water leaks from the seams, and machine sewing also has low work efficiency, so high frequency waves or hot air are often used to heat-seal the sheets. However, even if an attempt is made to join the laminated sheets having the vinylidene fluoride resin layer as the outer surface using heat-sealing sewing, the vinylidene fluoride resin layer and the waterproof layer resin on the lower surface do not adhere to each other, and therefore, this sheet also Furthermore, further improvements are desired. Problems to be Solved by the Invention The present invention provides an extremely useful waterproof sheet that has excellent stain resistance and weather resistance, can be sewn with heat fusion, and has durable stain resistance. This is what we are trying to provide. The present invention also provides a method for sewing such a waterproof sheet. Means for Solving the Problems According to the present invention, there is provided a waterproof sheet that can be sewn by heat-sealing, and this sheet has natural rubber, synthetic rubber or synthetic rubber on the surface or both front and back surfaces of the fibrous base fabric. In a waterproof sheet having a waterproof layer made of resin, a vinylidene fluoride resin layer is formed as the outermost layer on both the front and back surfaces, and an acrylic resin layer, a polyurethane resin layer, or a cyanoethylated ethylene layer is formed inside the vinylidene fluoride resin layer on both the front and back surfaces. - A vinyl alcohol copolymer layer is formed. According to the present invention, there is also provided a heat fusion sewing method characterized in that the outermost vinylidene fluoride resin layers on both the front and back surfaces of the waterproof sheet are superimposed and joined by heat fusion. An example of the waterproof sheet of the present invention will be explained with reference to FIG. In the embodiment of the waterproof sheet of the present invention shown in FIG. Vinylidene fluoride resin layers 3, 3' are formed on top of the film. Between these waterproof layers 2, 2' and the vinylidene fluoride resin layers 3, 3', there is an acrylic resin layer, a polyurethane resin layer, or a cyanoethylated ethylene-vinyl alcohol copolymer layer continuous with these layers 3, 3'. Combined layer 4,
4' is formed. In another embodiment of the waterproof sheet of the present invention, the waterproof tanks 2, 2' as described above are omitted, and the acrylic resin layer,
A polyurethane resin layer or a cyanoethylated ethylene-vinyl alcohol copolymer layer can be directly formed on the front and back surfaces of the fibrous base fabric 1 to serve as a waterproof layer. Alternatively, the waterproof tanks 2, 2' and the acrylic resin layer, polyurethane resin layer or cyanoethylated ethylene-vinyl alcohol copolymer layer 4,
Any other layer may also be formed between it and 4'. Furthermore, both or one of the waterproof layers 2 and 2' may be omitted, or both or one of the waterproof layers 2 and 2' may be omitted and any other layer may be formed in its place. It's okay. That is, the essential requirements for the waterproof sheet of the present invention are that it has a fibrous base fabric as an inner layer, that a waterproof layer exists, that a vinylidene fluoride resin layer is formed as the outermost layer on both the front and back surfaces, and Inside the vinylidene fluoride resin layer on both the front and back surfaces, an acrylic resin layer, a polyurethane resin layer, or a cyanoethylated ethylene-vinyl alcohol copolymer layer is formed continuously with this layer. However, the greatest feature of the present invention is that the protective layer of vinylidene fluoride resin, which was conventionally common sense to be formed only on one surface due to its usage and required performance, is now formed on both the front and back surfaces, overturning this common sense. Surprisingly, this not only achieved the purpose of protection, but also made it possible to perform heat-sealed sewing. The present invention will be explained in more detail below. The fibrous base fabric used in the waterproof sheet of the present invention includes natural fibers such as cotton and linen, inorganic fibers such as glass fiber, carbon fiber, and metal fibers, and recycled fibers such as viscose lace and quinpra. etc., semi-synthetic fibers such as di- and tri-acetate fibers, and synthetic resins,
For example, polyamide (nylon 6, nylon 66
etc.) fibers, polyester (polyethylene terephthalate, etc.) fibers, aromatic polyamide fibers, acrylic fibers, polyvinyl chloride fibers, polyolefin fibers, and the like. The fibers in the base fabric may be in any form such as short fiber spun yarn, long fiber yarn, split yarn, or tape yarn, and the base fabric may be a woven fabric, a knitted fabric, a nonwoven fabric, or a composite fabric thereof. It may be either. Generally, the fibers used in the waterproof sheet of the present invention are preferably polyester fibers, preferably in the form of long fibers (filaments), and preferably in the form of a plain woven fabric. Further, a woven fabric constructed by stacking parallel warp and weft yarns so as to cross each other and pressing them with leno yarns is particularly preferable. The fibrous base fabric is useful for increasing the mechanical strength of the resulting tarpaulin sheet. In the present invention, a waterproof layer is formed on the surface or both front and back surfaces of a fibrous base fabric to form a waterproof sheet. Materials for this waterproof layer include natural rubber, neoprene rubber, chloroprene rubber, silicone rubber, and hypalon. Other synthetic rubber or PVC
resin, ethylene-vinyl acetate copolymer (EVA) resin, acrylic resin, silicone resin,
Urethane resin, polyethylene (PE) resin, polypropylene (PP) resin, polyester resin, fluorine resin, and other synthetic resins can be used. The waterproof layer made of such a material has a thickness sufficient to provide the resulting waterproof sheet with the desired waterproof properties, flame retardance and mechanical strength, for example, 0.05 mm or more, preferably 0.05 to 2.0 mm. It has a thickness. These waterproof layers are coated on the fibrous base fabric by known methods such as topping, calendering, coating, and dipping using rubber or resin films, solutions, pastes, or straights as described above. can be formed into These rubbers or resins may contain plasticizers, stabilizers, colorants, ultraviolet absorbers, and other functional agents. A vinylidene fluoride resin layer is formed as the outermost layer on both the front and back surfaces of the waterproof sheet according to the present invention. As vinylidene fluoride resin, in addition to vinylidene fluoride monopolymer, vinylidene fluoride
A monomer containing mol% or more and copolymerizable with this,
For example, tetrafluoroethylene, trifluoroethylene,
A copolymer obtained by copolymerizing one or more monomers selected from vinyl fluoride, ethylene chloride trifluoride, fluorochlorovinylidene, vinylidene hexafluoride, etc. is used. In some cases, a mixture of these homopolymers or copolymers with other resins having good compatibility with them may also be used. Examples of resins having good compatibility with such vinylidene fluoride resins include polymers or copolymers mainly composed of methyl methacrylate or methyl alcohol, polyurethane resins, and cyanoethylated ethylene-vinyl alcohol copolymers. be. However, the amount of these other resin components is preferably within 30 PHR of the constituent resin amount. This vinylidene fluoride resin layer may contain processing aids such as stabilizers and lubricants and UVA, if necessary. In particular, the addition of UVA prevents photodeterioration of these resins near the bonding surface with the acrylic resin layer, polyurethane resin layer, or cyanoethylated ethylene-vinyl alcohol copolymer layer formed inside the acrylic resin layer, if necessary. It is preferable because it means However, the amount of UVA that is compatible with the vinylidene fluoride resin in a homogeneous phase is not very large, and is generally 3% or less. Furthermore, since the vinylidene fluoride resin layer is generally extremely thin, it cannot be expected that the waterproof layer will be completely protected by UVA alone from this layer. However, since the vinylidene fluoride resin layer protects only the surface layer of the sheet, it has a thickness of 0.3 to 10 μm.
The thickness is preferably 1 to 5 μm, and more preferably 1 to 5 μm. In the present invention, an acrylic resin layer is provided immediately inside the outermost vinylidene fluoride resin layer on both the front and back surfaces.
A polyurethane resin layer or a cyanoethylated ethylene-vinyl alcohol copolymer layer is formed. The thickness of these layers 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 preferably a resin whose main component is a polymer or copolymer whose main monomer is an ester of C ₁ -C ₄ alcohol of acrylic acid or methacrylate. The main constituent monomers of such acrylic ester resins are specifically methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate, butyl acrylate, and butyl methacrylate,
Particularly preferred are methyl acrylate and methyl methacrylate. Comonomers to be copolymerized with these main constituent monomers include, for example, esters of _C1 to _C12 alcohols of acrylic acid or methacrylic acid, vinyl fluoride, vinylidene fluoride, vinyl chloride, vinylidene chloride, vinyl acetate,
Monomers include styrene, acrylonitrile, methacrylonitrile, and butadiene. These copolymers are not limited to random copolymers, but may also be graft copolymers. For example, a polymer obtained by adding vinylidene fluoride to a methyl methacrylate polymer and then grafting the same can also be used. Although acrylates containing amino groups, imino groups, ethyleneimine residues, and alkylene diamine residues can also be used, particularly preferred results are obtained when using acrylates containing aziridinyl groups. The acrylic resin layer may contain a small amount of other resin having 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 can be said of the cyanoethylated ethylene-vinyl alcohol copolymer.
Furthermore, ultraviolet absorbers (UVA) may be added to these resin layers in order to provide durable weather resistance. The amount of UVA to be added is preferably determined so as to block approximately 50% or more of incident ultraviolet rays. The amount of UV blocking is determined by the concentration of UVA in these resin layers containing UVA and the thickness of this layer, but if the UVA concentration is too low, it is necessary to increase the thickness of these resin layers. Therefore, the UVA concentration of these resin layers should preferably be 0.3% or more, more preferably 1.0% or more. However, if the UVA concentration in this resin layer is too high, it may bleed to the interface with the vinylidene fluoride resin layer constituting the outermost layer and reduce the adhesive strength with this layer, which is not preferable. Of course, the compatibility with these resins and vinylidene fluoride resins differs depending on the type of UVA, so the upper limit of its concentration differs, but even benzotriazole-type UVA, which has a relatively high affinity for vinylidene fluoride resins, can also be used. If it exceeds 30 PHR, the two layers tend to peel off at the interface, so it is preferable to keep it at about 30 PHR or less. As UVA,
Not only benzotriazole-based resins, but also benzophenone-based resins, salicylic acid ester-based resins, or copolymerized resins of these and other resins can be used, and there are no particular limitations. When manufacturing the waterproof sheet of the present invention, for example, a sheet with a waterproof layer formed on the surface or both front and back surfaces of a fibrous base fabric is first manufactured, and then an acrylic resin, a polyurethane resin, or a cyanoethylated ethylene-vinyl alcohol copolymer is used. may be coated, and then vinylidene fluoride resin may be applied and formed. Alternatively, vinylidene fluoride resin, vinylidene fluoride resin/acrylic resin, polyurethane resin, or cyanoethylated ethylene-vinyl resin prepared separately may be coated on both the front and back surfaces. A laminated film of alcohol copolymer may be attached. If the thickness of the laminated film of vinylidene fluoride resin or vinylidene fluoride resin/acrylic resin is thin and there is a problem with workability, it is preferable to use a waterproof film such as a PVC film with a thickness of 30 to 50 μm. It is also possible to prepare a laminated film made of vinylidene fluoride resin/acrylic resin, polyurethane resin, or cyanoethylated ethylene-vinyl alcohol copolymer/PVC resin, etc. using the material as a support, and then adhere this to the above-mentioned sheet. Although the production of such a laminated film is not particularly limited, it is possible to coextrude a flat sheet or a cylindrical object by making the resin of each layer flow in a composite manner from a composite T die or a composite cylindrical die,
From the viewpoint of interlayer adhesion and productivity, it is preferable to take the film in a conventional manner and further heat treat it if necessary. The polyurethane resin used in the present invention can be freely selected in terms of its use form, and plasticizers, stabilizers, colorants, lubricants, and various other tactile agents can be freely added within known ranges. Examples of polyurethane resins, particularly thermoplastic polyurethane elastomer resins useful in the present invention are shown below. As the polyurethane elastomer, one obtained by reacting an organic polyisocyanate with a polymeric polyol and, if necessary, a chain extender is used. Organic polyisocyanates include aliphatic, cycloaliphatic or aromatic polyisocyanates, such as hexamethylene diisocyanate, lysine diisocyanate, cyclohexylene diisocyanate, dicyclohexylmethane diisocyanate, isophorone diisocyanate, tolylene diisocyanate, xylylene diisocyanate, phenylene diisocyanate, Examples include diphenylmethane diisocyanate (MDI), biphenylene diisocyanate, naphthylene diisocyanate, and the like. Among these, MDI or an organic diisocyanate mainly composed of MDI is preferred. Examples of the polymer polyol include polyether polyols, polyester polyols, polyether ester polyols, polymer polyols, and mixtures of two or more thereof.
Polyether polyols include those obtained by polymerizing or copolymerizing (block or random) alkylene oxides (ethylene oxide, propylene oxide, butylene oxide, etc.), heterocyclic ethers (tetrahydrofuran, etc.),
Examples include polyethylene glycol, polypropylene glycol, polyethylene-propylene (block or random) glycol, polytetramethylene ether glycol, polyhexamethylene ether glycol, polyoctamethylene ether glycol, and mixtures of two or more thereof. As polyester polyol,
Dicarboxylic acids (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-octamethylene diol, neopentyl glycol, bishydroxymethylcyclohexane, bishydroxyethylbenzene, alkyl dialkanolamine, etc.), such as polyethylene adipate, poly Examples include butylene adipate, polyhexamethylene adipate, polyethylene/propylene adipate, polylactone diols such as polycaprolactone diols, and mixtures of two or more thereof. As the polyether ester polyol, ether group-containing diols (the above-mentioned polyether diols, diethylene glycol, triethylene glycol, dipropylene glycol, etc.) or mixtures of these and other glycols are combined with the above-mentioned dicarboxylic acids or dicarboxylic acid anhydrides (phthalic anhydride, etc.). acid, maleic anhydride, etc.) and alkylene oxide, such as poly(polytetramethylene ether) adipate. In addition, as the polymer polyol, ethylenically unsaturated monomers (acrylonitrile, styrene, etc.) and those obtained by polymerizing them. The average molecular weight of the polymer polyol (by hydroxyl value titration) is usually 500 to 5000, preferably 700 to 5000.
4000, particularly preferably 2000 to 3500. As the chain extender, low-molecular polyols with a molecular weight of less than 500, such as ethylene glycol, propylene glycol, 1,4-butanediol,
1,6-hexanediol, diethylene glycol, triethylene glycol, thiodiglycol (thiodiethanol, etc.); polyamines, e.g.
Aliphatic diamines such as ethylene diamine, propylene diamine, butylene diamine, and hexamethylene diamine; alicyclic polyamines such as piperazine, 1,4-diaminopiperazine, 1,3-cyclohexylene diamine, and dicyclohexylmethane diamine; diphenylmetal diamine; Aromatic polyamines such as diamine, phenylene diamine, aromatic-aliphatic polyamines such as xylylene diamine, hydrazine and monoalkylhydrazine; alkanolamines such as ethanolamine, propanolamine; and mixtures of two or more thereof. It will be done. Among these, preferred are low molecular diols (especially ethylene glycol). However, it is not limited to the above examples, and any other thermoplastic polyurethane resin can be used, and it is not limited to ester-based, ether-based, etc. ) You can use anything that can be worn. The waterproof sheet thus obtained has excellent stain resistance and weather resistance, and can be sewn by heat fusion. That is, overlap these two waterproof sheets,
The outermost vinylidene fluoride resin layers on the front and back surfaces are brought into contact with each other and fused and bonded using ultrasonic heating, high-frequency heating, or hot air. When heat-sealing is performed in this way, a sheet that does not have a vinylidene fluoride resin layer, an acrylic resin layer, a polyurethane resin layer, or a cyanoethylated ethylene-vinyl alcohol copolymer layer on its lower surface, as in conventional waterproof sheets. In the case of the waterproof sheet of the present invention, the adhesive strength was extremely small at 0 to 3 kg/3 cm, but in the case of the waterproof sheet of the present invention, the adhesive strength was 6 to 10 kg/3 cm, which is much lower than the practically required approximately 5 kg/3 cm. This is a preferable value that exceeds this value. Although it is conceivable to sandwich a film made of resin that provides favorable adhesive strength between the two seals and fuse them together during such heat fusion sewing, in this case, the adhesion to the waterproof sheet would be lacking. Therefore, the adhesive strength is 3~4Kg/
The length is about 3 cm, and it is difficult to position the necessary parts during fusion work, which is not favorable for work.
It is also possible to partially form these resin layers on the bottom surface instead of a continuous layer on the bottom surface, but in this case, the work of applying these resin layers during sewing is troublesome and reduces workability. , harming the working environment. Therefore, as in the waterproof sheet of the present invention, if these resin layers are formed as a continuous layer on both the front and back surfaces from the beginning, the waterproof sheet itself can be manufactured at low cost and easily. It has the advantage that sewing can be done on any part that requires sewing. Examples Hereinafter, the present invention will be further explained with reference to Examples. Example 1 A vinylon fiber canvas having the following structure, density 20/3 x 20/4/45 x 38, and weight 350 g/m ² was used as a base fabric, which was blanched and dried. Next, this base fabric was prepared with the following composition: PVC resin...80 parts by weight Butylbenzyl phthalate...68 parts by weight Epoxidized soybean oil...7 parts by weight Calcium carbonate...20 parts by weight Cadmicium barium stabilizer...3 parts by weight Pigment ...8 parts by weight of toluene (solvent) ...After being immersed in a processing solution consisting of 130 parts by weight, it was squeezed between rollers to a coating amount of 100%, dried at 90°C for 1 minute, and then heated to 180°C.
The PVC was gelled and fixed by heat treatment at ℃ for 1 minute to create a waterproof sheet. The thickness of the waterproof layer of this tarpaulin sheet was 0.3 mm. On both the front and back sides of this waterproof sheet, a KFC sheet manufactured by Kureha Chemical Industry Co., Ltd. [vinylidene fluoride resin (2-3 μm)/acrylic resin (2-4 μm)/PVC
The PVC side of the resin (45 μm) was attached to the waterproof sheet surface using heat (product sheet). Separately,
Polyurethane resin is applied to the front and back sides of this waterproof sheet.
It was coated to a thickness of 7 μm, and a vinylidene fluoride resin film (3 μm) was adhered thereon (product sheet). The conditions for applying the polyurethane resin are as follows. Resin composition Nitsuporan 3022 (solid content 35%) 100 parts by weight Coronate L 15 parts by weight (all of the above are products for urethane processing by Nippon Urethane Co., Ltd.) Processing conditions 60 mesh gravure coat, 25 g/m ² It was applied at the rate of Separately, a cyanoethylated ethylene-vinyl alcohol copolymer was applied to both the front and back sides of this waterproof sheet to a thickness of 7 μm, and a vinylidene fluoride resin film (3 μm) was attached to make a sheet (product sheet). . For comparison, a conventional sheet () was prepared in exactly the same manner as above except that these resin films (3' and 4' layers) were not created on the back side.
was manufactured. For each of these four samples, overlap the edges by 3 cm as described in the text above,
Output 2KW, frequency 40.68MHz in this superimposed part
High frequency treatment was performed for 3 seconds using a high frequency oscillator. The average peel strength of the bonded parts of the heat-sealed sewn sheets obtained in this way was determined as follows:
In the case of () and (), each 8.5Kg/3cm, 8.5
Kg/3cm and 8.4Kg/3cm, and in the case of the comparison sheet () it was 0.5Kg/3cm. That is, the sheet of the present invention had a bonding strength sufficient for practical use, but the bonding strength of the comparative sheet was not practical. In addition, the parts of the sheets to be joined are stacked facing each other, and using a Leister hot air welding machine, a nozzle with a flat hot air outlet with a width of 3 cm is inserted between the stacked parts, and the nozzle is waterproofed along the sheet surface. from the nozzle while moving the sheet in the sewing direction.
Hot air at 400℃ was applied to melt the resin in a width of approximately 3cm. Following this melting operation, the overlapping portions were pressed with a pressure roller and fused and sewn. The peel strength of the fusion-sewn sheets thus obtained was almost the same as that of the sheets obtained by high-frequency welder sewing. Example 2 The same base fabric used in Example 1 was coated with a Hypalon resin waterproof layer, a silicone resin waterproof layer, and a silicone resin waterproof layer, respectively.
An EVA resin waterproof layer, an acrylic resin waterproof layer, and a urethane resin waterproof layer are formed, and the same KFC sheet used in Example 1 is pasted on both the front and back surfaces using Sony Chemical's acrylic adhesive SC462. It was made into a sheet (A group). Separately, sheets without these layers formed on the back surface were prepared and used as sheets (Group B). Each of these sheets was subjected to high frequency welding in the same manner as described in Example 1. As a result, the peel strength (Kg/3cm) was as follows.

[Table] Among Group B, those with waterproof layers made of Hypalon resin, silicone resin, and EVA resin are:
This is a comparative example. Furthermore, although the structure of the B group sheet, which uses acrylic resin and urethane resin as a waterproof layer, is different from the structure of the sheet of the present invention, the structure of the joint after these sheets are sewn by heat sealing is based on the sheet of the present invention. The structure is exactly the same as that of the same joint, and therefore the peeling strength of this joint is sufficient. Example 3 Glass dispersion: DE150 1/2 3.3S/55×51 torque satin weave with 290g/m ² strong greige fabric diameter 180Kg/3cm weft 167Kg/3cm was used, and the same method as in Example 1 was applied to both sides of this base fabric. A PVC waterproof layer containing a flame retardant (thickness: 0.07 mm) was then formed on this waterproof layer, and then the same KFC sheet used in Example 1 was melted with the PVC side facing the waterproof layer surface. I pasted it on. The waterproof sheet thus obtained has a base fabric and a vinylidene fluoride film layer on the surface that are non-flammable/flame-retardant, and the PVC resin of the waterproof layer is itself flame-retardant, and is further coated with a flame retardant. It has become a desirable membrane material as it exhibits high flame retardancy and can be said to be almost non-flammable as a whole. Also, this sheet
Since the outer surface was covered with a vinylidene fluoride film, it also had excellent weather resistance and antifouling properties. The thus obtained noncombustible sheet material was heat-sealed and sewn using a high-frequency welder and a Leister hot air welder in the same manner as in Example 1, and similar favorable results were obtained. This noncombustible sheet was extremely preferable as a membrane material for large air membrane structure domes. Effects of the Invention As can be seen from the above, the waterproof sheet according to the present invention has a protective layer made of vinylidene fluoride resin, so it maintains excellent stain resistance, weather resistance, and durability, and also has a protective layer made of vinylidene fluoride resin. Since the protective layer exists on both the front and back sides, it is extremely convenient to sew and use, and can be sewn easily and inexpensively by heat-sealing, and as a sheet with no seams and no risk of water leakage. Its industrial value is extremely large.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view schematically showing an example of the waterproof sheet of the present invention. 1... Fibrous base fabric, 2, 2'... Waterproof layer, 3,
3'... Vinylidene fluoride resin layer, 4,4'... Acrylic resin, polyurethane resin, or cyanoethylated ethylene-vinyl alcohol copolymer layer.

Claims (1)

[Claims] 1. Natural rubber on the surface or both front and back surfaces of the fibrous base fabric,
In a waterproof sheet having a waterproof layer made of synthetic rubber or synthetic resin, a vinylidene fluoride resin layer is formed as the outermost layer on both the front and back surfaces, and an acrylic resin layer is formed inside the vinylidene fluoride resin layer on both the front and back surfaces.
A waterproof sheet that can be sewn by heat sealing, characterized in that it has a polyurethane resin layer or a cyanoethylated ethylene-vinyl alcohol copolymer layer. 2. The waterproof sheet according to claim 1, wherein the acrylic resin layer, polyurethane resin layer, or cyanoethylated ethylene-vinyl alcohol polymer layer forms the waterproof layer. 3. The waterproof sheet according to claim 1 or 2, wherein the waterproof layer has a thickness of 0.05 to 2.0 mm. 4. Claims 1 to 3, wherein the acrylic resin layer is made of a resin whose main component is a polymer or copolymer whose main constituent monomer is an ester of _C1 to _C4 alcohol of acrylic acid or methacrylic acid.
A tarpaulin sheet as described in any of the paragraphs. 5. The waterproof sheet according to any one of claims 1 to 4, wherein the acrylic resin layer, polyurethane resin layer, or cyanoethylated ethylene-vinyl alcohol copolymer layer has a thickness of 0.5 to 30 μm. 6. The waterproof sheet according to claim 5, wherein the layer has a thickness of 2 to 20 μm. 7. According to any one of claims 1 to 6, the vinylidene fluoride resin layer is made of a resin whose main component is a vinylidene fluoride monopolymer or a copolymer containing 70 mol% or more of vinylidene fluoride. tarpaulin. 8. The waterproof sheet according to any one of claims 1 to 7, wherein the vinylidene fluoride resin layer has a thickness of 0.3 to 10 μm. 9 The thickness of the vinylidene fluoride resin layer is 1 to
The waterproof sheet according to claim 8, which has a thickness of 5 μm. 10 A waterproof sheet having a waterproof layer made of natural rubber, synthetic rubber, or synthetic resin on the surface or both the front and back surfaces of a fibrous base fabric, in which a vinylidene fluoride resin layer is formed as the outermost layer on both the front and back surfaces, and this A waterproof sheet is used in which an acrylic resin layer, a polyurethane resin layer, or a cyanoethylated ethylene-vinyl alcohol copolymer layer is formed inside the vinylidene fluoride resin layer of Overlap the resin layers,
A heat fusion sewing method characterized by joining these by heat fusion. 11. The method according to claim 10, wherein the means for thermal fusion is high frequency heating. 12. The method according to claim 10, wherein the means for thermal fusion is heating with hot air. 13. The method according to claim 10, wherein the means for thermal fusion is ultrasonic heating.