JPH0111461Y2 - - Google Patents

Description

[Detailed description of the invention] This invention is a greenhouse for agricultural products with improved heat retention.
The present invention relates to agricultural covering materials used in greenhouses and tunnel cultivation, and more specifically to agricultural films suitable for horizontal curtains in greenhouses and greenhouses.

Traditionally, films based on soft polyvinyl chloride, ethylene-vinyl acetate copolymer, polyethylene, etc. have been commonly used as agricultural covering materials.
Particularly in recent years, there has been a trend toward multiple coatings in order to prevent temperature drop inside greenhouses and greenhouses.

Curtains inside greenhouses and greenhouses are also a method of multiple coating, but while the inner lining of curtains is useful for keeping the temperature high inside the greenhouse or greenhouse, it also protects the inside and outside of the greenhouse. Due to the temperature difference, water droplets condensed on the inner surface of the house's outer covering material fall onto the inner curtain, forming a puddle on the inner curtain, and the weight of the water causes the so-called "fishbowl phenomenon" to occur in the curtain. Water puddles form on the film.

This makes it difficult to open and close the curtains, impairs the durability of the film, and sometimes the water bag acts as a lens that focuses sunlight, negatively impacting the growth of crops. A number of problems arose, particularly with horizontal curtains. In addition, rapid temperature changes inside and outside the greenhouse in the morning or evening cause fog and mist to form near the curtains, resulting in unnecessarily humid conditions for crops and causing disease.

In view of these circumstances, the inventors of the present invention have conducted extensive research into improvements and have arrived at the present invention.

That is, the present invention has a multilayer structure made of a thermoplastic resin that substantially transmits visible light, in which at least one layer has a structure in which, based on 100 parts by weight of the thermoplastic resin,
A composition containing 2 to 25 parts by weight of a composite oxide consisting of SiO ₂ and one or more metal oxides selected from the group of oxides of metal elements belonging to groups of the periodic table. The ratio of the refractive index n ²⁰ _D (A) of the thermoplastic resin to the refractive index n ²⁰ _D (B) of the composite oxide, n ²⁰ _D (A)/n ²⁰ _D (B), is 0.99 or more and 1.02. Multilayer body 1, which has a composition within the following range, and at least one other layer is a thermoplastic resin layer that does not contain the composite oxide.
The perforated film, which is characterized by having at least one through hole ² with a diameter of 9 mm or less per square meter of area, is transparent to visible light and does not substantially transmit infrared rays, so that the temperature inside the greenhouse can be reduced. It was discovered that it is extremely effective in keeping the body warm, and that the "fishbowl phenomenon" does not occur.

In other words, the composite oxide blended into the thermoplastic resin substantially prevents radiation (infrared rays) from passing through the ground at night, so it exhibits excellent heat retention. By providing through holes with a diameter of 9 mm or less in the composite film, the water that has accumulated on the laminated film flows down from the through holes in an appropriate cycle, thereby preventing the occurrence of the "fishbowl phenomenon."

Note that the feature of providing through holes in the multilayer film is most effective when used as a horizontal lining curtain in a house or greenhouse.

In other words, water droplets condensed on the inner surface of the house exterior film fall onto the interior curtain film,
A puddle of water gradually forms on the top of the film, but
Due to the interfacial tension of the water at the through-holes, it immediately turns into water droplets and forms a water film without flowing down from the holes. In addition, water accumulation increases to some extent,
When the weight of the water droplets becomes too much to support due to the interfacial tension of the water, they will flow down through the holes, and this situation will be repeated, resulting in the "fishbowl phenomenon" in curtains with perforated films. ” not only does not occur, but also forms a water film in the pores to prevent the penetration of radiation from above ground at night. This, combined with the radiation opacity of the composite oxide, improves the heat retention effect in the greenhouse. significantly improve.

In addition, when the perforated film of the present invention is used as an agricultural covering material such as a curtain, it is possible to prevent the generation of fog and mist, improve droplet flow, and maintain low humidity within the perforated film covering. It has remarkable effects, such as reducing the incidence of diseases and increasing crop yields.

The coating material of the present invention is an extremely useful material that can be widely used for the outside lining of agricultural greenhouses, greenhouse lining curtains, tunnel coverings, mulching, etc.

The present invention will be explained in more detail below.

The thermoplastic resin used in the present invention is not particularly limited, and includes, for example, polyolefin resins such as polyethylene and polypropylene, polyolefin copolymers such as ethylene-vinyl acetate copolymer, ionomer resins, vinyl These resins include alcohol resins, polyvinyl chloride, polystyrene resins, acrylic resins, polyester resins, polycarbonates, polyamide resins, saturated polyester resins, etc. alone or as a blend of each other.

SiO ₂ and the periodic table used in this invention,
A composite oxide consisting of one or more metal oxides selected from the oxides of metal elements belonging to the group , , has the general formula (SiO ₂ )x.(MαOβ)y.nH ₂ O or (SiO ₂ ) x.(MαOβ)y.(RγOδ). nH ₂ O, etc., where M is a metal element belonging to the periodic table group, and R is the periodic table group.
Represents a metal element belonging to the group, α and γ are integers 1
or 2, β and δ are integers 1 or 2
or 3, n represents zero or a positive number, and x, y, and z are selected so that the refractive index of the composite oxide can be as close as possible to the refractive index of the olefin resin according to the gist of the present invention. represents a positive number that is determined to be a positive value. Furthermore, as long as the gist of the present invention is not compromised, (SiO ₂ ) x. (M ¹ αOβ) y ₁ . (M ² αOβ) y ₂ …
It may have the general formula (M ^m αOβ)ym.nH ₂ O, and may further contain a small amount of impurities such as other metal oxides.

Examples of the metal elements mentioned above include:
Na, K, B, Be, Mg, Ca, Ba, A, Zn,
Examples include Ti, Zr, Pb, Sn, etc.

Among these, A, Ti, Mg, Ca, Na, etc. are particularly preferred from the viewpoint of refractive index control and cost.

Furthermore, it is also possible to add various additives such as a weathering agent, an anti-drop agent, a coloring agent, a processing aid, and a stabilizer to each resin layer as necessary.

The multilayer film of the present invention can be manufactured by any method such as the usual multilayer inflation processing method, multilayer T-die film processing method, lamination method, etc. Even if the multilayer structure is two layers, 3
Even if it is a layer, it is not particularly limited.

Further, the positions where the through holes with a diameter of 9 mm or less, which are a feature of the present invention, are provided are not particularly specified, and may be at regular pitches or at random positions. The diameter of the pores is preferably 9 mm or less in order to form a water film with an appropriate amount of water, but is more preferably 1 to 6 mm in view of the strength of the film and the water flow cycle.

Further, the number of through holes can be any number as long as it is one or more ^per square meter of area, taking into consideration the strength of the film.

The method of perforating the multilayer film according to the invention is not particularly limited, and it may be manufactured by any method such as a mechanical punching method or a melt perforation method.

[Brief explanation of the drawing]

FIG. 1 is a partially enlarged and cutaway perspective view of a perforated agricultural film according to the present invention. Figure 2a,
b and c are cross-sectional views showing the layer structure of the agricultural perforated film. The symbols in the diagram are as follows. 1... Layer containing composite oxide, 2, 3... Upper and lower film or sheet layers, 4... Through hole.

Claims (1)

[Claims for Utility Model Registration] (1) A multi-layer structure made of a thermoplastic resin that substantially transmits visible light, in which at least one layer has a composition of 100 parts by weight of the thermoplastic resin containing SiO ₂ and a periodic acid. A composition comprising 2 to 25 parts by weight of a composite oxide consisting of one or more metal oxides selected from the group of oxides of metal elements belonging to the group shown in Table 1. A composition in which the ratio n ²⁰ _D (A)/n ^{20 D (B) of the refractive index n 20 D (A) of the plastic resin to the refractive index n 20} _D ⁽ _B ⁾ _of the composite oxide is in the range of 0.99 or more and 1.02 or less. The multilayer body 1 is a layer consisting of a thermoplastic resin layer that does not contain the composite oxide, and at least one other layer is a thermoplastic resin layer that does not contain the composite oxide.
An agricultural perforated film with excellent heat retention properties that is transparent to visible light and substantially impermeable to infrared rays, characterized in that at least one perforated film is provided per m ² . (2) The diameter of the through hole provided in the multilayer body 1 is 1 mm or more and 6 mm.
A film according to claim 1 of the following utility model registration claims.