JPS60210924A - Agricultural cover material - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an agricultural covering material used for tunnel cultivation, greenhouse cultivation, etc.

-M Examples of agricultural covering materials used for tunnel cultivation, greenhouse cultivation, etc. include synthetic resin films such as polyethylene, polyvinyl chloride, polyester, and ethylene-vinyl acetate Jjilf combination. These synthetic resin films are
Although it is highly translucent, it does not itself have hygroscopicity or moisture permeability, so the inside of the coating tends to become humid or overhumidified. Furthermore, since it does not have air permeability, it has the disadvantage that the internal temperature of the coating increases (approximately 40° C. or higher during the day) even in the low temperature period of winter. In particular, when the distance between the crop and the covering synthetic resin film is narrow or the two are in contact, such as in tunnel cultivation, frost falling on the covering synthetic resin film may damage the crops in winter. It also has the disadvantage of being cooled and causing frost damage. Among these problems, high humidity and high temperatures inside the coating encourage the propagation of pathogenic bacteria in crops, leading to withering of crops, and in some cases, even complete extinction. A section is installed to ventilate the air inside the coating at appropriate time intervals. however,
Performing ventilation at appropriate intervals in this manner is extremely complicated. Therefore, in order to solve such problems, it has been considered and partially implemented to use a nonwoven fabric made of synthetic resin fibers such as polyester or polyolefin in place of the above-mentioned covering synthetic resin film. Since the nonwoven fabric has voids, it has a certain degree of ventilation. Therefore, although it is effective to some extent in preventing high temperature and high humidity inside the coating, this nonwoven fabric has voids, so it tends to release solar energy accumulated during the day at night, and its heat retention is poor. It has the disadvantage of being insufficient.

In addition, since no measures have been taken to prevent frost damage for both the synthetic resin film and the nonwoven fabric, the reality is that frost damage is prevented using soft straw or the like.

This invention was made with the aim of solving the above-mentioned problems, and is an agricultural technology in which flexible linear heating elements are distributed at appropriate intervals in a sheet-like mesh body. The gist of this article is covering materials for

In other words, this agricultural covering material has a mesh structure and has sufficient ventilation, so it prevents high temperatures inside the covering and
Demonstrates excellent effectiveness in preventing high humidity. In addition, this agricultural covering material has linear heating elements distributed in a distributed manner, and by energizing the linear heating elements to generate heat during the low-temperature winter season, frost that has fallen on the covering material and surface can be melted. By removing the coating, it is possible to prevent frost damage, and the heat generated by the coating increases the temperature inside the coating, thereby providing a sufficient heat-retaining effect.

Next, the present invention will be explained in detail based on examples.

FIG. 1 is an external perspective view of one embodiment of the present invention. That is, this agricultural covering material 1 has a plurality of visible linear heating elements 2 arranged at predetermined intervals and a plurality of reinforcing cotton threads 3 arranged perpendicularly thereto. It is constructed by laminating and bonding two sheets of polyvinyl alcohol (rPVAJ) based sheet-like network body 4 in a vertically open state using a PVA based binder. 5 is a flexible power supply line for energizing the linear heating element, and the end is energized: a (
(not shown). Here, the PVA-based sheet-like network 4 includes not only a network made of completely saponified polyvinyl acetate (hereinafter abbreviated as rPVAcJ), but also
It also includes networks made of partially saponified copolymers, and also includes networks made of saponified copolymers of vinyl acetate and other heptamers. In the case of partial saponification of PVAc or saponification of a copolymer of VAc and other monomers, the content of components other than PVA is set to 30% (mol%, the same hereinafter) or less, and within this range. A net-like body composed of the following is included in the range of the PVA-based sheet-like net-like body.

The agricultural covering material 1 as described above is manufactured, for example, as follows. That is, first, PVA with an average polymerization degree of 1400 or more and a saponification degree of 98.5% or more is added with a plasticizer such as glycerin or polyalkyl ether, or a water-soluble,
Aqueous liquefaction is carried out by adding a splitting accelerator such as thermoplastic resin,
This is the casting method.

A PVA film is produced by forming a film using a known film forming method such as a coagulation method. In this way, when using a PVA film made using PVA with an average degree of polymerization of 1400 or more and a degree of saponification of 98.5% or more, the resulting PVA sheet-like network will have a lower practical strength and dimensional stability. suitable. Next, as shown in FIG. 2, this PVA-based film is heated at a temperature of at least 5.5 times, preferably 6 to 6. The stretched film 8 is stretched to double its original size, and then split using a splitting roll 7 having a large number of cutting blades 6 on the outer circumferential surface, and a striped cut of a predetermined length is made in the stretched film 8 in the same direction as the running direction (direction of arrow B). Add a lot of 9s. It is preferable in terms of stretchability to set the stretching temperature of the pvA film to 180°C or higher (the upper limit is 220 to 230°C, the temperature at which thermal decomposition does not occur) as described above, and in this case, the stretching ratio is set to 5.5 times The above setting is preferable in terms of the splitting properties of the stretched film 8 and the practical strength and one-dimensional stability of the obtained PVA sheet-like network body 4. Next, the stretched film 8a with the striped cuts 9
is heat-treated at a temperature of 180° C. or higher to set it in a stretched state. When the heat treatment is performed at a temperature of 180°C or higher (the upper limit is 220 to 230°C, which is the temperature at which thermal decomposition does not occur), a sufficient heat setting effect can be obtained, and the resulting PVA sheet network 40 has a stable dimension. Improves sex. Then,
The stretched film 8a with the striped cuts set in the stretched state in this way is stretched in a direction perpendicular to the direction in which the striped cuts 9 are formed, thereby expanding its width. The width is widened using a known cross guider method, spring method, or the like. the result,
As shown in Figure 3, PVA has a network structure.
A system network 4 is obtained. Next, this PVA-based network 4
As shown in FIG. 4, a plurality of flexible linear heating elements 2 made of cotton thread as a core material and coated with a strip of copper foil wound spirally are arranged side by side at predetermined intervals. and both ends of each
It is connected to a flexible power supply line 5 for energization extending in a direction perpendicular to the linear heating elements 2, and a plurality of cotton threads 3 are connected so as to be perpendicular to the plurality of flexible linear heating elements 2. are placed side by side at predetermined intervals. Then, in that state, another P
The VA-based network bodies 4a are stacked and bonded together using a PVA-based binder. In this case, since the PVA-based net-like body 4 has a weak tensile strength in the same direction as the width expansion direction, the two PVA-based net-like bodies 4
．． 4a are overlapped and bonded together so that their width expanding directions are perpendicular to each other. In this way, an agricultural covering material 1 as shown in FIG. 1 is obtained.

This agricultural covering material 1 has a mesh structure and has sufficient ventilation, so it can prevent the inside of the covering from becoming hot and humid, and the linear heating element 2 is energized to generate heat (
For example, by generating heat so that the temperature in the vicinity of the heating element reaches 50 to 60°C, it exhibits a frost-proofing effect in winter, and also exhibits a sufficient heat-retaining effect inside the coating. In order to maximize this effect, the porosity of the mesh should be 5 to 50%.
It is preferable to set it within the range of . In other words, if the porosity is less than 5%, there is a risk that ventilation will be poor and it will be necessary to create an opening for ventilation, whereas if it exceeds 50%, the ventilation will be too large and the inside of the coating will be damaged. This is because heat retention becomes worse. ° The porosity can be easily adjusted by adjusting the width expansion ratio and the number of laminated sheets. In particular, when a PVA-based sheet-like mesh material is used as the material for the covering material as in this example, the characteristics of PVA are as follows: 1. Heat resistance does not deteriorate over a long period of time; 2. The coating material has a low infrared transmittance, and has excellent hygroscopicity and moisture permeability, so it exerts a kind of humidity control effect.The coating material has a long lifespan, and also protects against sunlight accumulated during the day. The emission of energy at night (radiative cooling) is suppressed, and in combination with the heat generated by the linear heating element, the heat retention of the coating material is significantly increased, and ■ Prevention of high humidity, excessive humidity, and dew condensation within the coating, as well as humidity. It will also have the effect of preventing shortages. Furthermore, the covering material of the above embodiments does not use a PVA sheet-like network made simply by weaving or knitting pvAIM fibers in the warp and warp, but by stretching and widening the PVA film. Since a PVA-based sheet-like network body made by heat treatment is used, in addition to the effects (1) to (4) above due to the general properties of PVA, the following excellent effects are achieved. In other words, when the PVA-based sheet-like network absorbs moisture caused by frost during frost, if heat is generated by the linear heating element, the PVA-based sheet-like network will shrink, causing the mesh to shrink. Since the dimensions of the material become smaller and the porosity automatically becomes smaller, the heat retention property is significantly improved, and an extremely large effect can be obtained in preventing frost damage.

In addition, in the above example, as the material of the agricultural covering material,
A PvA sheet-like net material made by 90% stretched weaving, width widening, and heat treatment is used, but instead, a net material made by weaving PVA fibers in one knit, etc. may be used, or a non-woven fabric-like material may be used. It goes without saying that you can also use the one that has been prepared. Further, polyester finished in a non-woven fabric, woven or knitted, 90% stretched, woven, widened, heat treated, etc. may also be used. Furthermore, a sheet-like net-like body formed in a similar manner using a resin other than the above-mentioned synthetic resin may be used, or a natural sheet-like net-like body such as cheesecloth, for example, may be used. In addition, the flexible linear heating element is not limited to one in which a strip of copper foil is spirally wound around a cotton thread core, and flexible electric wire such as copper wire may also be used. good. The arrangement state may also be in a houndstooth pattern rather than in a parallel arrangement, or may be in a meandering arrangement. Furthermore, the linear heating element is not arranged between two sheet-like net-like bodies, but on the inner surface (coated inward facing surface) of one sheet-like net-like body or a laminated and integrated sheet-like net-like body. It may be placed in Furthermore, when three or more sheet-like net-like bodies are laminated and integrated, they may be placed between the eyebrows as appropriate. In addition, in the above example, cotton thread for reinforcement is used, but
Threads made of other materials may be used, or may be omitted if reinforcement is not required.

As described above, in the agricultural covering material of the present invention, the visible linear heating elements are distributed in the sheet-like mesh body at appropriate intervals, so that the inside of the covering does not become hot or humid. It is highly effective in preventing the spread of disease and prevents disease by maintaining the inside of the cover in a suitable growing environment for crops, without the complicated work of opening and closing the openings at appropriate intervals. The occurrence can be effectively prevented. In addition, this agricultural covering material instantly melts and removes frost that has fallen on the surface of the covering material due to the heat generated by the linear heating element, effectively preventing frost damage, and reducing the temperature inside the covering by the linear heating element. can be maintained at a high level due to the heat generated. Therefore, it becomes possible to block the harmful effects of nighttime radiation cooling on crops.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of an embodiment of the present invention, FIG. 2 is an explanatory diagram of manufacturing a sheet-like net-like body, FIG. 3 is a partially enlarged view of the sheet-like net-like body obtained thereby, and FIG. Figure 1 is a manufacturing explanatory diagram. l... Agricultural covering material 2... Flexible linear heating element 3
...Cotton thread 4,4a...PVA sheet-like network 5...Power line patent applicant Kanebo Co., Ltd. agent Patent attorney Yukihiko Nishifuji Figure 1 Figure 2

Claims (1)

[Scope of Claims] +11 An agricultural covering material, characterized in that flexible linear heating elements are distributed in a sheet-like mesh body at appropriate intervals. (2) Agricultural covering material according to claim 1, wherein the sheet-like network is constructed using a polyvinyl alcohol-based material. (3) The polyvinyl alcohol-based material is stretched with respect to the polyvinyl alcohol-based film. The agricultural covering material according to claim 2, which is a polyvinyl alcohol network obtained by split weaving, widening, and heat treatment. (4) Stretching the polyvinyl alcohol film. Split weaving, widening, and heat treatment. The agricultural covering material according to claim 3, wherein the polyvinyl alcohol-based sheet-like network obtained by laminating and adhering the warp and warp. (5) The flexible linear heating element has a thread as a core material The agricultural covering material according to any one of claims 1 to 4, which is constructed by winding a strip of copper foil in a spiral shape around the sheet-like net-like body. The agricultural covering material according to any one of claims 1 to 5, wherein a reinforcing filament is disposed so as to intersect with the flexible linear heating element. (7) Sheet-like mesh-like material The agricultural covering material according to any one of claims 1 to 6, wherein the body has a porosity of 5 to 50%.