JPH09300511A - Heat insulating material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To inexpensively obtain an agricultural heat insulating material, especially, a water absorbable heat insulating material for cultivativing a strawberry by laminating a porous film and a nonwoven fabric and setting the absorbing speed of waterdrops dripped on the rear surface of the film to specific sec or less. SOLUTION: A heat insulating material is constituted by laminating a porous film and a nonwoven fabric. The absorbing speed of waterdrops of this heat insulating material is set to 60sec or less. When the absorbing speed of waterdrops exceeds 60sec, the absorbing speed becomes markedly slow because of partial irregularity or possibility not perfectly absorbing waterdrops is partially generated. The average pore size of the porous film is set to about 10-1,500μm. If the average pore size is small, the absorbing speed of generated dew becomes low and, if the average pore size becomes too large, the heat insulating effect of the film becomes low. Therefore, waterdrops dripped on a strawberry is rapidly removed and the damage ratio of a strawberry is lowered and yield is enhanced. Further, the absorption of the radiant heat of the heat of the earth is good and heat insulating effect and heat transfer are well-balanced and, therefore, the total heat insulating effect is enhanced.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The heat insulating material of the present invention relates to a heat insulating material for agriculture, and more particularly to a heat insulating material for strawberry cultivation.

[0002]

2. Description of the Related Art Films, non-woven fabrics and the like have been widely used as heat insulating materials for agriculture. For example, JP-A-59-16
No. 6021 proposes a laminated film for promoting the cultivation of strawberries, tomatoes and the like. However, although this film has a herbicidal effect and a heat retaining effect, it has no water permeability. As described above, the commonly used heat insulating material film generally has no water permeability. Some films have fine holes formed to impart moisture permeability, but cheap films often lack hydrophilicity themselves and have almost no water permeability. Many hydrophilic films are expensive, and they are economically unsuitable as agricultural materials that are consumed in large quantities.

It is easier to impart hydrophilicity to a non-woven fabric than a film, but it has a drawback that it is inferior to the film in terms of heat retention. Also, the water once absorbed remains as it is,
It has the drawback of staying wet.

It is known that when the strawberries are cultivated in a greenhouse, the night dew is condensed and adheres to the strawberries to damage them. Therefore, if the night dew that has condensed and dropped does not immediately touch the strawberries, the yield of strawberries is improved, which is economically advantageous.

It is also known that the color of strawberries is subtly influenced by the temperature of the environment, and the coloration of strawberries is significantly different when the temperature is 1 ° C. higher. Strawberry coloring is a very important factor in determining the quality of strawberries and directly affects the price. Therefore, if the heat retention effect is good, it is economically advantageous for strawberry growers.

[0006]

DISCLOSURE OF THE INVENTION An object of the present invention is to inexpensively supply an agricultural heat insulating material, particularly a water absorbent heat insulating material for strawberry cultivation.

[0007]

Means for Solving the Problems The present inventors have tried to combine various films and non-woven fabrics, and studied the heat retaining effect and water absorption of the heat insulating material, and as a result, completed the present invention. The present invention is a heat insulating material, characterized in that a porous film and a non-woven fabric are laminated and the absorption rate of water drops dropped on the film surface is within 60 seconds.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The porous film used in the present invention is economically advantageous in that it has a small thickness, and may be 5 μm or more which allows lamination. For the material of the film, polyolefin is economically advantageous, such as polyethylene,
Polypropylene is preferred. There are films of polyethylene terephthalate, nylon, cellophane, etc., but they are more expensive than polyolefins.

The holes in the film preferably have an average diameter of about 10 to 1500 μ. More preferably 100
Is ~ 500μ. If the average diameter is small, the absorption rate of dew condensation will be small. If the average diameter is too large, the heat retaining effect of the film is reduced.

The number of holes depends on the average diameter, but is 1
The number of pieces / cm ² or more is preferable. More preferably 10 / c
m ² or more. If the density of pores is too low, water droplets may remain.

The color of the film is preferably black. Black is most preferred for good absorption of daylight. In addition, it is preferable that the film is a surface material rather than a non-woven fabric because it absorbs sunlight better. Since the film may come into direct contact with food, for safety reasons, it is preferable to film the film.
In the same sense, the non-woven fabric under the film is also preferably black.
This is because when the film is thin, the color of the underlying nonwoven fabric can be seen through the film.

From the viewpoint of safety, it is preferable that the film and the non-woven fabric are bonded by heat. If an adhesive is used, the solvent of the adhesive may come into contact with food. In the same sense, thermal bonding is also preferable for the method of manufacturing a nonwoven fabric. Thermal bonding is used in the method of making nonwoven fabrics using spunbond and binder fibers. Since spunbonds are suitable for mass production, it is often economically disadvantageous to produce spunbond. Therefore, it is economically advantageous to use the binder fiber. It is preferable that the binder fiber is also a raw material.

A hydrophobic film, such as a polyethylene film, may be subjected to surface treatment such as electric discharge machining so as to improve adhesion and hydrophilicity.

As the binder fiber, it is preferable to use a core-sheath composite of a low melting point component and a high melting point component, or a binder fiber of a side-by-side composite fiber. For example, Bell Combi 6 manufactured by Kanebo Co., Ltd., in which the low melting point component is polyolefin and the high melting point component is polyethylene terephthalate.
There are 080 type and ES type of Chisso Co., Ltd. in which the low melting point component is polyethylene and the high melting point component is polypropylene. The binder fibers are usually mixed in an amount of 10% by weight or more, but preferably 15% by weight or more in terms of strength.

The other fibers of the non-woven fabric may be common fibers.
For example, natural fibers, cotton, hemp, wool and the like are used, but recycled fibers such as rayon and acetate are preferable for use in foods, and synthetic fibers such as polyethylene, polypropylene and polyethylene terephthalate are preferable in terms of cost.

As a method of improving the water absorption of the nonwoven fabric, there is a method of applying a large amount of a hydrophilic oil agent. Also,
It is preferable to mix 1 to 10% of highly hydrophilic fiber, for example, a fiber made of a cross-linked product of polyacrylic acid sodium salt manufactured by Kanebo Co., Ltd., Bell Oasis (trade name), because the hydrophilicity is dramatically improved. 1% by weight of Bell Oasis mixed
If it does not satisfy the above condition, the mixing of the fibers is likely to be insufficient and the water absorption rate becomes uneven. In addition, even if mixed in an amount of 10% by weight or more, the water absorption rate was not significantly improved,
Considering that the above fibers are expensive, it is not economically preferable. A more preferable mixing amount is 3 to 5% by weight in view of the balance between the effect and the economical efficiency.

If the laminated thickness of the non-woven fabric and the film is too large, the heat insulating effect is increased and the heat transfer of the geothermal heat is deteriorated, which is not preferable. In addition, the length of winding is shortened and the work for laying is increased, which is not preferable. Appropriate thickness is preferable, but it depends on the material etc.
The degree is preferred. More preferably, it is 0.5 to 1.5 mm.

In the same sense, the basis weight of the non-woven fabric is 20 to 250 g.
/ M ² is preferable. More preferably 50-150 g
/ M ² . Far-infrared radiation cotton, antibacterial cotton, mildew-proof cotton, etc. may be used for the non-woven fabric within a range that does not cause a problem in food hygiene.

The water absorption rate of the heat insulating material of the present invention has an average value within 60 seconds. If it exceeds 60 seconds, the absorption speed may be remarkably slowed due to partial unevenness, or it may not be completely absorbed. Preferably 20
It is within seconds, more preferably within 10 seconds. The higher the absorption rate, the more preferable.

In the present invention, the water drop absorption rate is 50% on the market.
A buret of ml was installed at a height of 10 cm, one drop of ion-exchanged water was dropped, and it was visually judged to measure the time taken for the water drop to be absorbed. The measurement was performed every 10 cm square, and 10 points were measured in the width direction and the machine direction.

[0021]

EFFECTS OF THE INVENTION The heat insulating material of the present invention has a high absorption rate for dew condensation water droplets, and therefore has an excellent effect of promptly removing water droplets dropped on strawberries. Therefore, the damage rate of strawberries is reduced and the yield is improved. In addition, the radiant heat of the geothermal heat is well absorbed, and the heat insulation effect and the heat transfer are well balanced, so that the total heat retention effect is excellent. Therefore, the temperature of the surface of the heat insulating material can be kept high, the coloring of the strawberries is improved, and the added value of the strawberries is improved.

After the petals of the strawberries are scattered, in the case of a film that does not absorb water, the petals adhere to the film to which water is attached and firmly adhere to each other. I couldn't blow it away. However, when the heat insulating material of the present invention is used, moisture such as night dew does not remain on the film surface, so that the petals do not adhere and the petals can be easily removed by air. The attachment of the petals leads to the attachment of water, which causes the generation of gray mold, and when attached to the strawberries, it causes the quality of the strawberries to be significantly impaired.

[0023]

【Example】

Example 1 100% of fabric weight 100g / m ² and thickness 1.2mm which used 100% of 51% of black dyeing binder fiber 2d made by Kanebo Co., Ltd.
In order to improve the hydrophilicity of the thermal bond nonwoven fabric, the hydrophilic oil agent produced from the vegetable oil component was sprayed at 0.5% by weight and dried.

This non-woven fabric and a low-density polyethylene film having a hydrophilic property improved by electric discharge machining of black having a thickness of 15 μ are provided with a density of 10 pieces / cm ² and an inlet diameter of about 400 μ.
A heat insulating material of the present invention was manufactured by opening a hole having an exit diameter of about 200 μm in the film with a hot needle and at the same time, by heat fusion, laminating and bonding the nonwoven fabric.

The average absorption rate of water drops of this heat insulating material was 32 seconds. The maximum absorption rate was 43 seconds. Further, even after sufficiently absorbing water, even if it was pressed with a finger, water did not flow back to the film surface.

The strawberry ridges are covered with a commonly used black low density polyethylene film. As a test, this heat insulating material was laid between the strawberry ridges of a greenhouse-grown strawberry and laid on top of it so that the strawberry would bear fruit. Although the strawberry was damaged by the dew condensation that occurred at night and the strawberries were damaged, the yield of the strawberry of the test product harvested the next day was improved by 38% compared with the normal product. In addition, the yield improvement rate when laying only the above non-woven fabric is 8
%, And the effect of the heat insulating material of the present invention was remarkable.

The surface temperature of the heat insulating material at night is 2c deep.
When the temperature drops below the soil temperature of m, the average is 1.
It was 8 ° C higher and 1.4 ° C higher than the nonwoven fabric alone. For this reason, the strawberries were colored better than the normal product and the comparative product containing only the non-woven fabric, and the quality of the strawberries was significantly improved.

Example 2 As in Example 1, except that only the non-woven cotton formulation was changed,
The water absorption rate of the manufactured heat insulating material was measured, and the results are shown in Table 1. As the bell oasis, a gel strength enhanced type 9d, 51 mm manufactured by Kanebo Co., Ltd. was used.

[0029]

[Table 1]

Example 3 No. 2 of Example 2. In the same manner as in 3, set the binder mixing ratio to 1
Change to 0,15% by weight, and replace the binder with regular polyester black original cotton SD 1.5d, 51mm
It was used.

A non-woven fabric having a binder content of 10% by weight has a small tensile strength, and care has to be taken when handling it with a film, but a non-woven fabric having a binder content of 15% by weight has a sufficient tensile strength. It was easy to handle when it was attached to the film. The average water absorption rates of these heat insulating materials of the present invention were 18 seconds and 17 seconds, respectively, and were not affected by the mixing ratio of the binder fibers.

Claims (3)

[Claims] 1. A heat insulating material in which a porous film and a non-woven fabric are laminated and the absorption rate of water droplets dropped on the film surface is 60 seconds or less. 2. The heat insulating material according to claim 1, wherein the porous film is colored black. 3. A greenhouse cultivation method in which the heat insulating material according to claim 1 or 2 is used as an underlayment of a strawberry when strawberry is internally grown.