JPS6240964B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a double-covered agricultural house, and more particularly to a double-covered agricultural house that is excellent in drip-free properties, translucency, heat retention, and durability.

After the war, Japan's facility agriculture achieved remarkable development with the use of plastic film, which began in 1962, and hot-air heaters, which appeared in 1960. In today's world, where the price of heavy oil has skyrocketed to an abnormally high level, it is no longer possible to maintain agricultural management with conventional facility cultivation that relies on heavy oil. Under such severe circumstances, all kinds of measures to realize energy-saving agriculture are being considered mainly by national and public research institutes, and one of them is the development of agricultural covering materials with higher heat retention and consideration of how to use them. be. One method is to coat glass or plastic films such as polyvinyl chloride, ethylene monovinyl acetate copolymer, polyethylene, etc. in two layers with appropriate spacing, and use the insulation effect of the air layer in the middle to retain heat. There is a so-called double-covered house that attempts to improve the heat retention, and although such a double-covered house is structurally superior in heat retention and has a high energy saving effect, it has the following drawbacks. The reality is that it has not been widely disseminated.

First of all, the fatal drawback is that the plastic films conventionally used for double-coated houses, such as glass, polyethylene, ethylene-vinyl acetate copolymer, and polyvinyl chloride, have hygroscopic and moisture-permeable properties. Since there is virtually no moisture, mist tends to occur in the air layer between the double coatings due to the so-called supercooling phenomenon, and many water droplets condense on the surface of the coating material, reducing transparency and hindering crop growth. This is due to a significant decrease in the transmittance of sunlight, which is essential for photosynthesis. In addition, since the inside of the greenhouse tends to become humid or overhumidated, diseases such as gray mold, downy mildew, and sclerotium are likely to be induced, and the crops themselves grow weak and elongated.

Furthermore, conventionally used plastic films, especially those made of polyethylene and ethylene-vinyl acetate copolymers, have high transmittance to infrared rays mainly in the 6 to 17 micron wavelength range, so they can absorb solar energy stored during the day. They tend to radiate energy at night, and the heat retention properties of the materials themselves are insufficient, so even if they are used in a double-covered house, the expected energy-saving effect cannot be achieved.

Furthermore, plastic films such as polyethylene, ethylene-vinyl acetate copolymer, and polyvinyl chloride are easily degraded by ultraviolet rays and have poor weather resistance, and they also tend to get dirty and have reduced transparency, making them less durable. It is sufficient and can usually only be used for one year.

The inventors of the present invention have completed the present invention as a result of intensive studies to eliminate the above-mentioned drawbacks of existing double-covered houses made of covering materials such as glass and plastic films. The object of the present invention is to provide a double-coated house having excellent drip-free properties, translucency, heat retention, and weather resistance.

Other objects and effects of the present invention will become clearer from the following description. Therefore, the above purpose is to develop a double-coated agricultural house made of two layers of agricultural coating material with appropriate intervals, and to use a polyvinyl alcohol film as a multilayer coating material by stretching, splitting, and heat treatment. , a laminate obtained by adhesively integrating a reticular nonwoven fabric obtained by laminating and adhering at least one sheet of each of the reticulated materials obtained by widening the reticulated material and a polyvinyl alcohol film containing 5 to 30 mol% of olefin units. This is achieved by a double-coated agricultural house characterized in that a polyvinyl alcohol-based coating is applied with the surface facing outward, and an inner-layer coating material is a longitudinally orthogonal laminate of polyvinyl alcohol-axially stretched and heat-treated coatings.

Agricultural double-clad houses are generally made of glass, polyethylene, polyvinyl chloride, or ethylene.
This agricultural greenhouse has a structure in which it is covered with two layers of films or sheets made of vinyl acetate copolymer, polyester, etc. at appropriate intervals, and it retains heat by utilizing the insulation effect of the air layer contained in the space between the two layers. The aim is to improve energy efficiency and achieve energy savings. A method for covering glass or the above-mentioned plastic film or sheet in two layers is to form the house frame in two layers with appropriate spacing using steel frames or metal pipes, and then cover and fix the house frame to this with special fasteners such as screws and backers. However, there is also a so-called air house structure in which a bag-shaped plastic film or sheet is covered with a single house frame made of a steel frame or metal pipe, and an appropriate amount of compressed air is sealed and fixed. Good too. In short, any agricultural house may be used as long as it is covered with two layers of glass or plastic film or sheets with appropriate spacing, and the spacing is usually preferably about 3 to 30 cm. If the spacing is smaller than 3cm, the insulation effect due to the air layer contained in the space will be insufficient and undesirable.If the spacing is larger than 30cm, the house frame will become large, which is disadvantageous from an economical and operational point of view, and the air layer in the space will be insufficient. convection is likely to occur and the insulation effect is also reduced.

The agricultural double house referred to in the present invention means a structure similar to the above-mentioned agricultural double house.

Also, the polyvinyl alcohol film used in the present invention (hereinafter polyvinyl alcohol is abbreviated as PVA)
is preferably at least one type of PVA with an average polymerization degree of 1000 or more and a saponification degree of 98% or more, and if necessary, a plasticizer such as glycerin or polyalkylene ether, and a small amount of other water-soluble or A thermoplastic resin or the like is added to form an aqueous dispersion or solution, which is then formed into a film by a known film forming method such as a casting method, a coagulation method, or an extrusion method.

The reticulated nonwoven fabric applied to the present invention is made by laminating and adhering the reticulated material obtained by stretching, splitting, heat-treating, and widening the above-mentioned PVA coated material on the warp and warp, and can be easily produced by a known method. For example, a PVA film containing PVA with an average degree of polymerization of 1750 and a degree of saponification of 99.5% and 10% by weight of glycerin as a plasticizer is stretched at least 5.5 times, preferably 6 to 6.5 times, at 180°C or higher,
After splitting, the fibers are heat-treated at 200° C. or higher, and then widened by a cross guider method, a spring method, etc. to obtain a net-like body, which can be laminated and bonded warp-to-warp by a known method. In this case, if the PVA coating has an average degree of polymerization of 1000 or more and a degree of saponification of 98% or more, the obtained reticulated nonwoven fabric will have excellent practical strength and dimensional stability, and as will be described later, it is 5 to 30 mol%.
It is suitable when adhesively integrated with a PVA-based film containing olefin units or a heat-treated PVA film.

In addition, it is preferable that the stretching temperature is 180°C or higher in terms of the stretchability of the PVA film, and when the stretching ratio is higher than 5.5 times, the splitting properties and the obtained reticulated nonwoven fabric have good practical strength and dimensional stability. Similarly, it is suitable when adhesively integrated with a PVA-based film body or a heat-treated PVA film body. Furthermore, the heat treatment temperature is 200℃
The above is also preferable since the heat setting effect is sufficient and the obtained reticulated nonwoven fabric has good practical dimensional stability. The upper limit of the stretching and heat treatment temperature is a temperature that does not cause thermal decomposition, which is generally about 230°C.

To explain in more detail the aspect of the reticulated nonwoven fabric used in the present invention, as will be described later, it is a laminate obtained by adhesively integrating with a PVA film containing 5 to 30 mol% of olefin units or a heat-treated PVA film. In terms of performance, it is preferable to have the following.

That is, first of all, it is preferable that at least 80% of the split fibers constituting the reticulated nonwoven fabric generally have a width of 0.5 mm or more, as this is excellent in practical strength and the reinforcing effect of the above-mentioned PVA-based coating or heat-treated PVA coating is sufficient. . Such a reticulated nonwoven fabric can be easily obtained by appropriately selecting a splitting device and splitting conditions.

In addition, it is preferable that the porosity of the reticulated nonwoven fabric be 50% or less in terms of the reinforcing effect of the PVA film body or the heat-treated PVA film body, and the hygroscopicity, water absorbency, and dew condensation prevention property of the laminate obtained by integrating the adhesive. Furthermore, if necessary, it may be a film-like material with a porosity substantially close to 0%. Such a reticulated nonwoven fabric can also be easily obtained by appropriately selecting the widening magnification.

Furthermore, the reticulated nonwoven fabric used in the present invention is
A net-like body obtained by stretching, splitting, heat-treating, and widening a PVA coated body may be laminated and bonded by a known method, one sheet each for the warp and the other, or in some cases, many more sheets. Vinylon type, PVA for reinforcement
A material that is adhesive to the reticulated nonwoven fabric, such as a stretched tape, may be inserted at appropriate intervals. In addition, as a bonding agent for laminating and adhering the mesh to the warp and warp, any adhesive material is sufficient, but PVA-based materials are suitable in terms of weather resistance, hygroscopicity, water absorption, moisture permeability, and transparency. Preferably, a binder is used.

A PVA film containing 5 to 30 mol% (hereinafter mol% is abbreviated as %) of olefin units is a film made of modified PVA of a copolymer or polymer mixture containing 5 to 30 mol% of olefins. means and takes
A PVA-based film can be easily obtained by a known method. For example, saponified ethylene-vinyl acetate copolymer or pelletized water-containing
It can be easily obtained by forming a film from a blend of PVA and polyethylene pellets using a conventional melt extrusion method. Furthermore, if necessary, a plasticizer such as glycerin or polyalkylene ether or a weathering stabilizer may be appropriately added thereto, or a film may be heat-treated after forming a film.

In addition, as will be discussed later, if the content of the modified olefin is less than 5%, there will be problems with water resistance and practical dimensional stability, and if it is more than 30%, it will have poor moisture absorption, moisture permeability, water absorption, heat retention, etc. There are problems with weather resistance.

The outer coating material used in the present invention is a laminate in which the above reticulated nonwoven fabric and a PVA film containing 5 to 30% of olefin units (hereinafter abbreviated as PVA film) are adhesively integrated. After applying a binder using a known method such as a coater method or a dipping method, the PVA-based film is bonded and dried, or when a reticulated nonwoven fabric is obtained by laminating and adhering a reticulated material to a warp and a warp, a PVA-based film is applied. It can be laminated at the same time as the lamination adhesive mentioned above, or it can be used with reticulated non-woven fabric.
As a binder for adhesively integrating the PVA-based film, any material with adhesive properties may be used, but if it is hygroscopic,
It is preferable to use a PVA binder in terms of water absorption, moisture permeability, weather resistance, and transparency.

The characteristics and effects of the outer layer covering material used in the present invention will be described later, but taking advantage of the extremely excellent moisture absorption, water absorption, moisture permeability, heat retention, and weather resistance of the reticulated nonwoven fabric of the present invention made of PVA, On the other hand, in order to improve the water resistance and practical dimensional stability, which are disadvantageous, the film is adhesively integrated with a specific PVA film. That is,
As a hydrophilic synthetic resin, PVA has extremely excellent moisture absorption, water absorption, moisture permeability, weather resistance, and transparency that other synthetic resins do not have, but on the other hand, it has poor water resistance and has poor water permeability and blocking properties. , because it has great elasticity and easily becomes brittle at low temperatures and low humidity.
If the PVA material is coated as is, it has no practical use as an agricultural covering material. In order to eliminate the various drawbacks of such PVA material and make it possible to use it as an agricultural covering material, the present inventors first highly stretched a film made of PVA material and then subjected it to sufficient heat treatment. We proposed a method of laminating and adhering PVA-axially stretched and heat-treated film obtained by the process. It is true that PVA is achieved by the above method of the earlier application.
The poor water resistance and embrittlement at low temperatures and low humidity that glass has has been improved, and it can be used as a general agricultural covering material, but it cannot be used under harsh conditions such as the outer covering of greenhouses. In order to use it indoors, it was necessary to further improve the practical dimensional stability, and since no modification had been made to the water permeability, there was a problem that rainwater could seep into the greenhouse. In order to solve this problem and take advantage of the characteristics of the PVA material, it is important to adhesively integrate a specific PVA film and a reticulated nonwoven fabric.

As mentioned above, the PVA-based film is a film made of modified PVA containing olefin units in the range of 5 to 30%, and this PVA-based film has sufficient water resistance, water permeability, blockability, and elasticity. It has almost no embrittlement at low temperatures and low humidity, and also has a certain degree of hygroscopicity, water absorption, and moisture permeability, which is better than other hydrophobic synthetic resin coatings. Furthermore, it has good heat retention and weather resistance, but this
PVA-based coatings alone cannot be said to have sufficient hygroscopicity, water absorption, moisture permeability, and weather resistance.

As is clear from the above description, the outer coating material used in the present invention has extremely excellent hygroscopicity, water absorption, and moisture permeability of the reticulated nonwoven fabric made of PVA, and a certain degree of hygroscopicity of the PVA-based film. As I will discuss later in terms of water absorption and moisture permeability, even if the problem of hazyness and condensation in the space between the layers of the coating material in a double-coated house is solved,
Water resistance and low temperature properties of PVA film. When used as a house exterior lining due to its embrittlement resistance under low humidity conditions.
This eliminates the disadvantages of PVA, such as rainwater inflow and poor dimensional stability. PVA according to the present invention
If another hydrophobic synthetic resin film was used instead of the other hydrophobic synthetic resin film, the water resistance and practical dimensional stability would be solved, but the material would have no moisture absorption, water absorption, or moisture permeability, so it would be double-layered. It is not possible to prevent fogging and dew condensation in the spaces between the coating material layers of the covered house, and the heat retention and weather resistance are also insufficient. In addition, the PVA-based film alone has insufficient moisture absorption, water absorption, and moisture permeability, and if it cannot prevent the above-mentioned fogging and dew condensation, it will also have insufficient heat retention and weather resistance. .

Therefore, a more important point of the double-clad agricultural house of the present invention is that a special PVA coating material is used as the inner layer coating material. This point will be explained below.

The inner layer coating material of the agricultural double-coated house of the present invention is:
A laminated body of a PVA-axis-high-stretch heat-treated film or a laminated body of the PVA reticulated nonwoven fabric and a heat-treated PVA film that are adhesively integrated, the former will be described in detail first.

The orthogonal laminate of PVA-axially stretched and heat-treated film in the present invention is preferably a film mainly composed of PVA with an average polymerization degree of 1000 or more and a saponification degree of 98% or more at a temperature of at least 5.5% at 180°C or higher. 6 times or more, preferably 6 times
It is made by laminating orthogonally in the warp and warp direction PVA--axially stretched and heat-treated film bodies obtained by high-stretching up to 6.5 times and then heat-treating at 200°C or higher. for example
As mentioned above for the reticulated nonwoven fabric, the PVA film is produced by casting from an aqueous solution containing PVA as the main component.
It can be easily obtained by a wet method, an extrusion method, etc., and the obtained PVA film can be stretched by using a heated roller or heating chamber and using the speed difference between two sets of pinch rolls.
Multi-stage stretching may be performed if necessary. Further, the heat treatment may be performed by any known method, and generally a heated cylinder or chamber is used, but the latter method using a cylinder is preferred in order to further enhance the heat treatment effect. In this case, when the average degree of polymerization of PVA is 1000 or more and the degree of saponification is 98% or more, a PVA-axially stretched, heat-treated film body with excellent practical strength and dimensional stability can be obtained. It will be done. In addition, a stretching temperature of 180°C or higher is preferable from the viewpoint of stretchability of the PVA film body, and a heat treatment temperature of 200°C or higher provides sufficient heat setting effect, which is also suitable from the viewpoint of practical dimensional stability. . Furthermore, it is preferable that the stretching ratio is 5.5 times or more, more preferably 6 to 6.5 times, because as will be described later, practical strength and dimensional stability, particularly dimensional stability, are excellent.

To bond the thus obtained PVA-axially stretched and heat-treated film by orthogonal lamination to the warp and warp, a PVA-based binder, which is the same material in terms of hygroscopicity, water absorption, moisture permeability, durability, and transparency, is used. It is preferable. Furthermore, at least one sheet of PVA-axially stretched and heat-treated film may be laminated and bonded in each direction, and in some cases, more sheets may be laminated and bonded. Furthermore, vinylon tape, PVA stretched tape, etc. may be used for reinforcement. They may be inserted at appropriate intervals.

As mentioned above, the film body made of PVA has extremely excellent moisture absorption, water absorption, moisture permeability, weather resistance, and shielding properties of infrared rays in the 6 to 17μ wavelength range, that is, heat rays, so it has dehumidification, dew condensation prevention, and durability. Although it has high heat retention properties and is extremely useful as an agricultural covering material, it has poor water resistance, poor practical dimensional stability due to moisture absorption, blocking during water absorption, and significant swelling, and furthermore, it is difficult to use at low temperatures. Because it lacks practical strength due to embrittlement in low humidity conditions, it cannot be used as an agricultural covering material at all. In order to eliminate the drawbacks of such a PVA film and give it practicality as an agricultural covering material, the PVA film is uniaxially highly stretched and then heat treated.
The inner layer coating material used in the agricultural double-coated greenhouse of the present invention is one in which heat-treated coatings are laminated perpendicularly to the warp and warp. In other words, the PVA film is stretched and heat treated to increase the degree of crystal orientation and crystallinity, thereby imparting water resistance.However, the stretched PVA film absorbs moisture, and upon drying after absorbing water, the molecules are elongated and arranged. Due to the relaxation phenomenon of
To solve this problem, the degree of crystal orientation should be at least 0.92 or more, preferably 0.94 or more, and the degree of crystallinity should be at least 0.92 or more, preferably 0.94 or more.
It is important to perform uniaxial high stretching and heat treatment to 0.47 or more, preferably 0.50 or more. By setting the crystal orientation degree to 0.92 or more and the crystallinity degree to 0.47 or more, the above-mentioned
The shrinkage of the stretched and heat-treated film made of PVA due to the molecular relaxation phenomenon is about 2 to 3% or less, making it applicable as the inner layer coating material for double-covered agricultural greenhouses according to the present invention. to do so
Although it varies slightly depending on the film forming conditions of the PVA film body,
Usually the stretching ratio is at least 5.5 times or more, preferably 6
It is necessary to increase the heat treatment temperature by ~6.5 times to 200℃ or higher.

Naturally, if the stretching ratio and heat treatment temperature are further increased, the degree of crystal orientation and crystallinity will further increase, resulting in better water resistance and practical dimensional stability. There are limits;
Generally, the stretching ratio is preferably 6.5 to 7 times, and the heat treatment temperature is preferably 220 to 230°C.

However, since such PVA uniaxially highly stretched and heat-treated film bodies have the disadvantage of being extremely easy to tear in the direction of molecular arrangement, tear strength is improved by laminating and bonding at least one film perpendicular to the warp. .

As is clear from the above explanation, the weft/width orthogonal laminate of PVA uniaxially highly stretched and heat-treated film material used as the inner layer coating material for the double-coated agricultural greenhouse of the present invention has excellent dehumidification properties, dew condensation prevention properties, durability, and heat retention properties. Excellent in aqueous properties, practical dimensional stability, and mechanical strength.
As will be described later, this material exhibits effective properties as an inner layer covering material for agricultural double-covered greenhouses.

Furthermore, the above-mentioned PVA uniaxially highly stretched and heat-treated film body is hard and somewhat lacking in flexibility, so in order to improve this, a plurality of PVA uniaxially highly stretched and heat-treated film bodies are arranged in the same direction as the molecular arrangement. It is more preferable to have a plurality of substantially straight and fine cuts, since the cuts impart flexibility. In addition, it is preferable that the length of such substantially straight and fine cuts is 5 to 100 mm, and if it is smaller than 5 mm, the flexibility of the orthogonal laminated body of the PVA uniaxially highly stretched and heat-treated film may be slightly impaired. If it is larger than 100 mm, the productivity of warp/warp lamination adhesive tends to become unstable.

Furthermore, substantially straight and fine cuts are
0.5 in the width direction of PVA-based uniaxially stretched, heat-treated film body
It is preferable that they are applied at intervals of ~20mm, and 20mm
If the diameter is larger than 0.5 mm, the resulting PVA-based uniaxially highly stretched, heat-treated film body will have slightly insufficient flexibility, and if it is smaller than 0.5 mm, there will be problems in terms of production stability.

Next, a laminate in which a PVA reticulated nonwoven fabric and a heat-treated PVA film are adhesively integrated to be used as the inner layer covering material of the agricultural double-covered greenhouse of the present invention will be described.

The PVA reticulated nonwoven fabric is the same as the reticulated nonwoven fabric used for the outer layer covering material of the double-coated agricultural house of the present invention described above, and its structure and characteristics are as described above.

Moreover, the heat-treated PVA film body used in the present invention is PVA
It is made by heat-treating a PVA film whose main component is at least 140°C, preferably 180°C or higher. The heat treatment is generally carried out using, for example, a heating chamber or a heating cylinder, but the latter is more suitable from the viewpoint of production stability and heat treatment effect. In this case, as will be described later, it is preferable for the heat treatment temperature to be 140° C. or higher, preferably 180° C. or higher, in terms of water resistance and practical dimensional stability.

Despite the fact that PVA-based coatings have excellent properties such as poor water resistance, poor practical dimensional stability, and embrittlement at low temperatures and low humidity,
It has no practical use when used alone.

The heat-treated laminate in which the reticulated non-woven fabric and the heat-treated PVA used for the inner layer coating material of the present invention are adhesively integrated has the following advantages: It is important to supplement this with practical dimensional stability as well as mechanical strength. Furthermore, even if the PVA film body is directly adhesively integrated with the specific reticulated nonwoven fabric referred to in the present invention,
Since the PVA coated body has extremely poor water resistance and is easily blocked and significantly expands and contracted, the resulting laminate is also inferior in practicality. Therefore, it is preferable to heat-treat the PVA coated body at at least 140°C or higher to form a PVA coat. . That is, by heat-treating the PVA film, the degree of crystallinity is increased and water resistance is improved, and moisture absorption, blocking upon water absorption, and significant swelling or expansion and contraction can be eliminated. Therefore, the heat treatment temperature is preferably higher, preferably at least 140℃, and 180℃ or higher.
It is more preferable that the temperature is higher than 0.degree. C., and the upper limit thereof is the temperature at which thermal decomposition occurs, generally 220 to 230.degree.

However, even if heat treatment improves the water resistance and practical dimensional stability of PVAM films, the expansion and contraction is limited to about 10 to 20%, and even at low temperatures and low humidity. Since no improvement has been made regarding the embrittlement of PVA, it is impractical to use the heat-treated PVA film alone, and it is essential to adhesively integrate it with the specific reticulated nonwoven fabric referred to in the present invention.

Thus, the laminate in which the PVA reticulated nonwoven fabric and the heat-treated PVA film are adhesively integrated, used in the present invention, has excellent hygroscopicity, water absorption, moisture permeability, heat retention, and durability.
Furthermore, it is an agricultural covering material with excellent water resistance, practical dimensional stability, and strength, and as will be described later, it exhibits extremely suitable characteristics as an inner layer covering material for double-covered greenhouses.

Any known method may be used to adhesively integrate the reticulated nonwoven fabric and the heat-treated PVA film. For example, if a binder is applied to a reticulated nonwoven fabric by a known method such as a roll coater method or a dipping method, then the heat-treated PVA film is bonded and dried, or if the reticulated material is laminated and bonded to the weft and warp to form a reticulated nonwoven fabric, the heat-treated PVA film is applied. The body may be bonded together at the same time as the above-mentioned lamination bonding. In addition, as a binder for adhesively integrating the reticulated nonwoven fabric and the heat-treated PVA film, any material with adhesive properties may be used. It is preferable to use a PVA-based binder as a material.

The agricultural double-covered house of the present invention uses a laminate in which the above-mentioned reticulated nonwoven fabric and a PVA film containing 5 to 30% of olefin units are adhesively integrated as an outer covering material, and a PVA uniaxially highly stretched and heat-treated film. The inner layer is coated with at least one of a laminated body perpendicular to the warp and the weft, or a laminated body in which a reticulated nonwoven fabric and a heat-treated PVA film are adhesively integrated.
The configuration and effects will be further explained below.

First, an important requirement regarding the structure of the double-covered agricultural greenhouse of the present invention is that a laminate in which a reticulated nonwoven fabric and a PVA film are adhesively integrated to be used as the outer layer covering material is attached to the outside of the house, that is, in contact with the outside air. On the other hand, it is necessary to cover it. That is, the PVA-based film was modified with olefins in the range of 5 to 30%.
Since it is a film made of PVA, it has good water resistance, but its hygroscopicity and water absorption are insufficient, and as will be discussed later, it is unsuitable because it lacks the effect of preventing fogging and condensation. With the PVA film on the outside
By coating the inside of the greenhouse with a reticulated non-woven fabric made of 100% PVA, the extremely excellent hygroscopic and water-absorbing properties of the reticulated non-woven fabric will reduce the occurrence of mozziness between the coating material layers of double-covered agricultural greenhouses and the surface of the outer coating material. This prevents dew condensation and eliminates the conventional problem of decreased light transmittance.

Furthermore, it contains 5 to 30% olefin units.
The hygroscopicity, water absorption, and moisture permeability of the PVA film are also essential properties for preventing the above-mentioned fogging and condensation. Otherwise, it will not be possible to prevent mist and dew from forming, and it will also be inferior in heat retention and weather resistance.

The inner layer covering material used in the double-covered agricultural greenhouse of the present invention is a uniaxially highly stretched, heat-treated PVA film orthogonal laminate, or a laminate in which a reticulated nonwoven fabric and a heat-treated PVA film are adhesively integrated are both made of 100% PVA.
Because it is made of double-covered greenhouses, there is no front or back when covering it, and either side can be placed on the inside. Due to its excellent hygroscopicity, water absorption, and moisture permeability, it can be used between the layers of the covering material in double-covered greenhouses and inside the greenhouse where crops are present. It can prevent mist formation and dew condensation on the surface of the coating material. Of course, if other hydrophobic plastic films are used, such as polyethylene, polyvinyl chloride, ethylene-vinyl acetate copolymer film, or polyester film, fogging and dew condensation cannot be prevented at all.

As explained above, a laminate in which a reticulated nonwoven fabric and a PVA-based film are adhesively integrated is used as the outer layer coating material, and the PVA-based film is coated on the outside.
PVA uniaxial high stretching made of 100% PVA, heat treatment orthogonal laminate of PVA film body or reticulated nonwoven fabric and heat treatment
By coating at least one type of laminate that is adhesively integrated with a PVA film as an inner layer coating material, the reduction in translucency due to the generation of haze and dew condensation, which were the drawbacks of conventional double-coated agricultural greenhouses, is reduced. This makes it possible to solve this problem and create a double-covered agricultural greenhouse that has excellent heat retention and durability. Furthermore, in the above-mentioned double-covered agricultural house of the present invention, the coating method for each coating material may be the same as the conventional method as described above, and the spacing between the outer layer coating material and the inner layer coating material may be the same as described above. From the viewpoint of heat retention, workability, and economy, it is preferable that the length be about 3 to 30 cm.

The thus obtained agricultural double-covered house of the present invention does not cause haze or dew condensation, which were the drawbacks of the conventional methods, and has excellent light transmission.It also has an energy-saving effect and is highly durable, allowing stable cultivation of crops. It is extremely effective.

Claims (1)

[Scope of Claims] 1. In an agricultural double-coated house made of two layers of coating material with appropriate intervals, a net-like shape obtained by stretching, splitting, heat-treating, and widening a polyvinyl alcohol film body. The outer layer is covered with a laminate in which a reticulated nonwoven fabric formed by laminating and bonding the body to the warp and a polyvinyl alcohol film containing 5 to 30 mol% of olefin units are adhesively integrated, with the polyvinyl alcohol film on the outside. , (a) Polyvinyl alcohol uniaxially highly stretched, heat-treated film body perpendicular laminate (b) Polyvinyl alcohol film body stretched, split,
The inner layer is coated with at least one kind of coating material selected from the group of laminates made by adhesively integrating a reticulated nonwoven fabric obtained by laminating and adhering a reticulated material obtained by heat treatment and widening, and a heat treated polyvinyl alcohol film. A double-covered agricultural house characterized by the following features: 2 Appropriate interval between outer layer coating material and inner layer coating material is 3~
The agricultural double-covered house according to claim 1, which has a length of 30 cm. 3 At least 80% of the split fibers constituting the reticulated nonwoven fabric
The agricultural double-covered house according to claim 1, wherein the double-covered agricultural house has a width of 0.5 mm or more. 4. The agricultural double-covered house according to claim 1 or 3, wherein the reticulated nonwoven fabric has a porosity of 50% or less. 5. The agricultural double-coated house according to claim 1, wherein the reticulated nonwoven fabric and the polyvinyl alcohol film are adhesively integrated via a polyvinyl alcohol binder. 6. The agricultural double-coated house according to claim 1, wherein the polyvinyl alcohol uniaxially highly stretched and heat-treated film has a degree of crystal orientation of 0.92 or more and a degree of crystallinity of 0.47 or more. 7. The agriculture according to claim 1 or 6, wherein the polyvinyl alcohol uniaxially highly stretched and heat-treated film has a plurality of substantially straight fine cuts in the same direction as the molecular arrangement. double cladding house. 8 Substantially straight and minute cuts have a length of 5~
The agricultural double-covered house according to claim 7, which has a diameter of 100 mm. 9 Substantially straight and fine cuts are made in the width direction of the polyvinyl alcohol uniaxially highly stretched and heat-treated film.
The agricultural double-covered house according to claim 7 or 8, wherein the double-covered house is coated at intervals of 0.5 to 20 mm. 10 Claim 1, in which a uniaxially highly stretched, heat-treated polyvinyl alcohol film body is integrated with orthogonal adhesive to the warp and warp, through a polyvinyl alcohol binder. Agricultural double-covered houses as described in Section 1. 11. The agricultural double-covered house according to claim 1, wherein the reticulated nonwoven fabric and the heat-treated polyvinyl alcohol film are adhesively integrated via a polyvinyl alcohol binder.