JPH09107815A - Sheet for heat insulation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a heat-insulating sheet capable of heat-insulating the surface of the ground on which plants are planted, and capable of rapidly raising the inner temperature of the covered ground with sunshine to eliminate a frosted or frozen state, even when the surface of the ground is frosted or frozen at low temperatures at night. SOLUTION: This sheet for insulating heat comprises a plain woven fabric using belt-like films having an IR light-reflecting property and belt-like films having an IR light-absorbing property as warps or wefts. The former films are obtained by subjecting a high density polyethylene film to an aluminum vacuum deposition processing, laminating a intermediate density polyethylene film to the treated film and subsequently cutting the laminate. The latter is obtained by kneading high density polyethylene with carbon black, forming the kneaded mixture into a film and subsequently cutting the film.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to
The present invention relates to a heat insulating sheet suitable for preventing frost and freezing on the ground on which a plant is cultivated.

[0002]

2. Description of the Related Art Conventionally, polyethylene is used as a heat insulating sheet for preventing frost and freezing on the ground on which plants are cultivated.
Synthetic resin sheets such as polyvinyl chloride and polyester are known. However, these synthetic resin sheets generally have a high infrared ray transmittance, and the heat retaining effect was not sufficient to prevent frost and freezing on the ground covered.

On the other hand, in order to reduce the infrared ray transmittance and enhance the heat retention effect, aluminum is vapor-deposited on the surface of a synthetic resin film, and a metal-coated sheet having an aluminum vapor-deposited surface covered with a protective film is prepared. There is known a protective sheet (Japanese Utility Model Laid-Open No. 4-19151) in which a tape cut into a narrow width is used as a warp and a tape obtained by cutting a synthetic resin sheet into a narrow width is used as a weft to perform a plain weave process.

However, even if such a protective sheet is used, the heat retaining effect is not sufficient in severe cold conditions, especially at night when the temperature is below 5 ° C below zero, and frost and freezing occur on the covered ground. I have something to do. In this sheet, since heat retention is imparted by infrared reflection, heat rays (infrared rays) from the outside of the coating space are blocked, so if frost or freezing occurs, this Contrary to the original heat retaining effect, the protective sheet keeps the coated surface cool. Therefore, even if sunshine starts and the temperature of the uncoated ground rises due to solar heat, the temperature of the ground does not rise on the coated surface, and it takes a long time for the frozen state to be resolved. was there.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned conventional problems, and keeps the ground on which a plant or the like is cultivated warm, and the ground is frosted or frozen during severe cold. Even in such a case, it is an object of the present invention to provide a heat insulating sheet that can effectively use geothermal heat and solar heat to quickly raise the temperature of the coated surface and eliminate a frosted or frozen state.

[0006]

The invention described in claim 1 according to the present invention for attaining the above object comprises a strip-shaped film having infrared reflectivity and a strip-shaped film having infrared absorbability, Each is characterized as being a knitted fabric as a warp or a weft.

The invention as set forth in claim 2 is characterized in that a band-shaped film having infrared reflectivity is used as a weft, and a band-shaped film having infrared absorption is used as a warp to form a knitted fabric.

According to the third aspect of the present invention, a band-shaped film obtained by laminating a film having infrared reflectivity and a film having infrared absorbability is used as at least one of warp and weft to form a knitted woven fabric. It is characterized by that.

The invention described in claim 4 is the same as claim 1 or claim 2.
In the inventions described in (3) and (3), the strip-shaped film having infrared reflectivity is a film obtained by subjecting a synthetic resin film to aluminum vapor deposition processing and further laminating a synthetic resin film.

The invention described in claim 5 is the same as claims 1 and 2.
In the inventions described in (3) and (3), the strip-shaped film having an infrared absorbing property is a synthetic resin film obtained by kneading carbon black into a synthetic resin to form a film.

The invention described in claim 6 is the same as claims 1 and 2.
In the inventions described in 3 and 3, the band-shaped film having infrared reflectivity is a synthetic resin film laminated with a synthetic resin film obtained by subjecting a synthetic resin film to aluminum vapor deposition, and the band-shaped film having infrared absorbing property is made of carbon as a synthetic resin. It is a synthetic resin film obtained by kneading black to form a film.

The invention described in claim 7 relates to claim 1,
In the inventions described in 2, 3, and 7, the infrared-reflecting band-shaped film is a high-density polyethylene film subjected to aluminum vapor deposition processing and further laminated with a medium-density polyethylene film. .

The invention described in claim 8 is the same as claim 1,
In the inventions described in (3) and (3), the band-shaped film having infrared absorbing property is a film obtained by kneading high-density polyethylene with carbon black to form a film.

Here, as the film having infrared reflectivity, the surface of a uniaxially stretched synthetic resin film having a thickness of 10 μm to 50 μm formed by a known method is vapor-deposited with aluminum to a thickness of 300 Å to 700 Å, A film obtained by coating the aluminum vapor-deposited surface with a synthetic resin film having a thickness of 10 μm to 40 μm by a known laminating method such as extrusion laminating or dry laminating or a known coating method such as dipping is used.

Alternatively, the aluminum vapor deposition process described above may be replaced by laminating an aluminum foil having a thickness of 5 μm to 30 μm by a known method.

Alternatively, 10 to 100, which is obtained by kneading 2 to 15 parts of aluminum powder, alumina, titania, zinc sulfide, zinc oxide, lead white, white carbon or the like pigment having high infrared reflectance with 100 parts of synthetic resin base resin. 1 μm thick
Axial stretched films are also included.

As the infrared absorbing film, 2 to 15 parts of black pigment such as carbon black, graphite, aniline black, cyanine black and acetylene black is mixed with 100 parts of synthetic resin base resin.
A uniaxially stretched film having a thickness of 10 to 100 μm can be used.

In laminating the synthetic resin film, any known laminating method can be used.

The strip-shaped film can be obtained by cutting the film obtained by the above method into a width of 2 mm to 20 mm by a known method. Further, the synthetic resin used is not particularly limited.

The heat insulating sheet according to the present invention is obtained by using the strip-shaped film obtained by the above-mentioned method, in which the area of the exposed portion having infrared reflectivity and the exposed portion having infrared absorbing property on one surface of the heat insulating sheet. It can be obtained by knitting by an appropriate method so that the area ratio (hereinafter referred to as the exposed surface area ratio) with respect to the area is 2: 8 to 8: 2. The area ratio of the exposed surface may be appropriately selected according to the required performance.

According to the first and second aspects of the present invention, a band-shaped film having infrared reflectivity and a band-shaped film having infrared absorption are used as warp yarns or weft yarns to form a knitted fabric. This makes it possible to prepare a sheet in which the infrared reflective surface and the infrared absorbent surface are alternately present on the surface of the sheet.

According to the invention of claim 3, a strip-shaped film obtained by laminating an infrared reflective film and an infrared absorbent film is used as a warp or a weft to form a knitted woven fabric. In the same manner as 2 and 2, it is possible to prepare a sheet in which the infrared reflective surface and the infrared absorbent surface are alternately present on the surface of the sheet. Further, according to this method, one surface can be made a surface having a whole infrared ray absorbing property and the other surface can be made a surface having a whole infrared ray reflecting property. And in this case,
For the purpose of heat retention, the surface having infrared reflectivity on the ground side and the surface having infrared absorbency on the outside are used.

According to the fourth, fifth and sixth aspects of the invention, the synthetic resin film can be provided with aluminum vapor deposition so as to have infrared reflectivity, and carbon black is kneaded with the synthetic resin to form a film. By doing so, it is possible to give infrared absorption.

According to the invention of claim 7, a medium density polyethylene film is used as the polyethylene film when the high density polyethylene film is subjected to aluminum vapor deposition processing and further laminated with the polyethylene film.

According to the eighth aspect of the present invention, it is possible to impart infrared absorption by kneading the high density polyethylene film with carbon black to form a film.

As described above, in the heat retaining sheet of the present invention, the infrared ray reflecting surface and the infrared ray absorbing surface are alternately present on the sheet surface.

Therefore, the infrared rays emitted from the ground due to the ground temperature are reflected toward the ground surface on the surface having infrared reflectivity. On the surface having infrared absorption, the infrared rays are once absorbed by the sheet and then radiated to the ground surface again as radiant heat as the sheet temperature rises.

Further, on the surface having the infrared absorbing property, the temperature of the sheet rises by absorbing the solar heat from the sun, and the radiant heat also increases accordingly, and the temperature inside the coated surface rises quickly.

As described above, according to the present invention, in addition to being excellent in heat retention, the temperature in the coating surface is rapidly increased, so that even if the ground is frosted or frozen during severe cold, It is possible to provide a heat insulating sheet that can effectively use solar heat and quickly raise the temperature of the coated surface to eliminate a frosted or frozen state.

The heat retention and the degree of temperature rise of the coated surface can be controlled by changing the area ratio of the exposed surface of the infrared reflective surface to the infrared absorptive surface. It is possible to create an optimal environment for the target plant by selecting an appropriate configuration according to the application and regional characteristics of use.

The heat insulating sheet in the present invention is made by knitting and weaving, and has appropriate breathability and high moisture permeability.
Therefore, it is possible to prevent the coated surface from being heated to a high temperature, to prevent the plant from being damaged by the high temperature, and to prevent the damage due to excessive humidity.

[0032]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

The infrared-reflecting strip-shaped film is a uniaxially stretched 25 μm-thick high-density polyethylene (hereinafter abbreviated as “HDPE”) film, on one side of which is vapor-deposited with aluminum to a thickness of 500 Å. Then, a 15 μm thick medium-density PE film is laminated on the aluminum vapor-deposited surface by extrusion lamination and cut into a width of 3 mm. A sectional view of the aluminum vapor deposition tape (2) thus obtained is shown in FIG.

The band-shaped film having infrared absorbing property is obtained by kneading 5 parts of carbon black with 100 parts of HDPE and cutting a uniaxially stretched HDPE film of 25 μm thickness formed by an inflation method into 6 mm width. . The strip-shaped film thus obtained is called a black tape (3).

The aluminum vapor deposition tape (2) is used as a weft,
Using the black tape (3) as warp, plain weave was performed so that the weaving density was 9 yarns / inch in both warp and weft, and an intended heat retaining sheet (1) having an exposed surface area ratio of approximately 5: 5 was obtained.
A plan view of the heat retaining sheet (1) is shown in FIG.

The heat insulating sheet of the present invention thus obtained, and the conventional heat insulating sheet using a transparent polyethylene film containing no carbon black for the weft yarn,
The result of comparing the temperature rise characteristics is shown in FIG. White circles are data relating to the heat insulating sheet of the present invention, and black circles are data relating to the conventional heat insulating sheet. As a measuring method, an incandescent lamp of 100 W was irradiated from the upper surface of the sheet to heat the sheet, and the temperature of the lower surface of the sheet was measured using a radiation thermometer to examine the change with time.

As shown in FIG. 4, it can be seen that the heat insulating sheet of the present invention has a temperature increase rate of about twice that of the conventional product.

As described above, according to the present invention, since the sheet has the infrared absorbing property, the temperature of the sheet rises quickly during sunshine, and the radiant heat accompanying the rise of the sheet temperature causes solar heat on the ground surface. It is easy to transmit, and the frozen state of the ground during frost and freezing can be quickly resolved.

According to the heat insulating sheet of the present invention, a band-shaped film having infrared reflectivity and a band-shaped film having infrared absorbability are used as a woven or knitted fabric, and the surface having infrared reflectivity and the infrared absorbability are provided. The surface with which it has is made to exist alternately on the surface of the sheet, but separately from this, a band-shaped film having infrared absorbing property is used for both warp and weft to make a woven or knitted fabric, and one surface is made of aluminum. A heat insulating sheet can also be obtained by vapor deposition or application of a substance having infrared reflectivity such as. Then, in this case, the surface having infrared reflectivity on the side of the ground is used with the surface having infrared absorbency being the outside.

[0040]

As described above, according to the present invention, in addition to being excellent in heat retention, even when the ground is frosted or frozen in severe cold, it is easy to absorb the radiant heat from the sunshine, so that the geothermal heat and the solar heat can be effectively used. By utilizing this, it is possible to quickly raise the temperature of the coated surface and eliminate the frosted or frozen state.

[Brief description of the drawings]

FIG. 1 is a plan view of a heat retaining sheet that is an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a strip-shaped film having infrared reflectivity.

FIG. 3 is an explanatory diagram of a comparison result of temperature rise characteristics of the present invention and a conventional product.

[Explanation of symbols]

 1 Heat insulation sheet 2 Black tape 3 Aluminum vapor deposition tape 11 High density polyethylene layer 12 Aluminum vapor deposition layer 13 Medium density polyethylene layer

Claims (8)

[Claims] 1. A heat insulating sheet comprising a band-shaped film having infrared reflectivity and a band-shaped film having infrared absorption as a knitted fabric as warp or weft, respectively. 2. A heat retaining sheet comprising a band-shaped film having infrared reflectivity as a weft, and a band-shaped film having infrared absorption as a warp as a knitted fabric. 3. A heat retaining sheet which is a knitted woven fabric, wherein a band-shaped film obtained by laminating an infrared reflective film and an infrared absorbent film is used as at least one of warp and weft. 4. The heat retaining sheet according to claim 1, wherein the strip-shaped film having infrared reflectivity is a synthetic resin film laminated with a synthetic resin film obtained by subjecting a synthetic resin film to aluminum vapor deposition. 5. The heat insulating sheet according to claim 1, wherein the band-shaped film having infrared absorbing property is a synthetic resin film prepared by kneading carbon black into a synthetic resin to form a film. 6. The infrared-reflecting band-shaped film is a synthetic resin film obtained by subjecting a synthetic resin film to aluminum vapor deposition processing and further laminating a synthetic resin film, and the infrared-absorbing band-shaped film is made of carbon black as a synthetic resin. The heat insulating sheet according to claim 1, which is a synthetic resin film formed by kneading and forming a film. 7. The heat insulating sheet according to claim 1, wherein the band-shaped film having infrared reflectivity is a high density polyethylene film subjected to aluminum vapor deposition and further laminated with a medium density polyethylene film. 8. The heat retaining sheet according to claim 1, wherein the band-shaped film having an infrared absorbing property is a film obtained by kneading high-density polyethylene with carbon black to form a film.