JPH10327684A - Shading net - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To relate to a light-shielding net mainly used for a house cover in various fields of agriculture, horticulture, or livestock, and has excellent durability and weather resistance to withstand long-term outdoor use. The object of the present invention is to provide a material which has good easiness and handleability and satisfies a demand for improvement of an internal environment covered with a light-shielding net. SOLUTION: A tape-shaped yarn 2 in which a non-woven fabric in which synthetic resin long fiber filaments are deposited and bonded in a non-directional manner at a high density is slit into a narrow width, and a synthetic resin flat yarn 3 is used.
Alternatively, the light-shielding net 1 is characterized by being thermally fused at least on one surface of a net base fabric 4 obtained by knitting or arranging filaments at an interval.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light-shielding net mainly used for a house covering in various agricultural, horticultural or livestock fields.

[0002]

2. Description of the Related Art Conventionally, in the cultivation of fruits and flowers,
For the purpose of forcing cultivation, cold protection and frost protection, polyvinyl chloride,
Background Art A so-called greenhouse cultivation in which a synthetic resin sheet such as polyethylene or ethylene-vinyl acetate copolymer is coated on the outside is performed. However, a house coated with a synthetic resin sheet of this type tends to have a large temperature rise in the daytime, and may exceed the optimum temperature for growing crops even in a low temperature period, and the inside of the house is closed. As a result, there is little exchange with the outside air, and there is a possibility that the growth of crops is hindered due to excess or deficiency of carbon dioxide gas or humid state, so that opening work such as rolling up the hem of the sheet for ventilation is required.

[0003] As a covering material having air permeability and requiring no opening work, a cold net or a coarse net-like material such as a woven fabric made of a monofilament or a flat yarn is used for growing crops in the sheet. Suitable temperature and humidity environment can be maintained, and the net-like object can block the direct sunlight to obtain an appropriate amount of light, and at the same time, light can be appropriately taken from the gaps in the net-like object. It is used for cultivation of many crops by expanding to the purpose of preventing overheating and drying in the high temperature period such as tea plants, soft crops, shiitake mushrooms, fruit trees, etc. that need to be used, and also used as shading nets in the livestock industry It is in.

The light shielding net is knitted or woven relatively coarsely so as to have a ventilation gap by using a synthetic resin thread such as high-density polyethylene. There is a light-shielding net composed of a flat yarn on which a metal layer such as aluminum is deposited.For example, a flat yarn obtained by slitting a synthetic resin film obtained by vacuum-depositing aluminum as a warp, and a transparent or translucent yarn as a weft. Light-shielding cloth
JP-A No. 60-100963), and a cover material for crop protection in which a flat yarn obtained by slitting a synthetic resin film obtained by vacuum-depositing aluminum is knitted in a zigzag shape between knitted chains in a zigzag shape. Have been.

[0005] By the way, the flat yarn on which aluminum is deposited has a low physical and chemical strength of the deposited film. That is, when the deposited layer comes into contact with air, an oxide film is formed and the metallic luster is impaired. Durability is a major problem, such as being transformed into aluminum oxide and becoming transparent. To improve this point, light-shielding nets and agricultural reflections are made using flat yarns with a protective layer formed by further coating the deposited layer with resin. Sheet (for example, Jikken 57-2315)
No. 0, Japanese Utility Model Publication No. 60-2918, Japanese Patent Application Laid-Open No. 1-320150, etc.) are disclosed.

However, the vapor-deposited flat yarn on which the protective layer is formed has a resin thickness of the protective layer of about 15 to 50 μm. The problem of durability has not yet been solved due to the tendency to stick and erosion from the damaged part. In addition, it has been pointed out that even a light-shielding net using vapor-deposited flat yarn absorbs light, absorbs heat itself, and raises the temperature inside the light-shielding net, resulting in an unsuitable growth environment for crops. I have.

[0007]

SUMMARY OF THE INVENTION In view of the state of the prior art as described above, the present inventor has proposed that, in the low temperature period, cold protection,
As a light-shielding net used for the purpose of frost prevention and heat shielding and light-shielding in high-temperature periods, it has excellent durability and weather resistance to withstand long-term outdoor use, and has good workability and handleability. The purpose is to provide those that satisfy the requirements for improvement of the internal environment covered by.

For this purpose, the present inventors have previously disclosed in Japanese Patent Application No. 7-338475 a nonwoven fabric in which long fiber filaments of an opaque synthetic resin are deposited and bonded in a high-density and non-directional manner. A new light-shielding net using a tape-like thread with a narrow slit was developed. That is, the tape-like yarn is used for at least one of a warp and a weft, and is knitted or woven or arranged to form a mesh-shaped light-shielding net. This tape-like yarn is white and has high light reflectance and low heat storage properties, so it is excellent in light shielding and heat shielding especially in the high temperature period in summer, but because the physical properties of the warp yarn are different. The weaving speed did not increase, and there were some difficulties in productivity. Also, in the case of arrangement intersection, there is a slight difficulty in the strength of the light shielding net itself.

[0009]

According to the present invention, a light shielding net which uses the above-mentioned tape-like yarn and solves the above-mentioned problems has been obtained as a result of various studies. The present invention has been completed by employing means for heat-sealing and integrating a tape-like yarn with a cloth. That is, a tape-like thread in which a nonwoven fabric in which synthetic resin long fiber filaments are deposited and bonded in a non-directional manner at a high density is slit into a narrow width is obtained by knitting or arranging or intersecting flat yarns or filaments of a synthetic resin. It is characterized by being heat-sealed at least on one side of the net base cloth at intervals.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, a non-woven fabric used for a tape-like yarn is made of a polyester resin, a polyamide resin, or the like in addition to a polyolefin resin as a synthetic resin. Must be composed of fibers. This is because the shading net is often used outdoors for a relatively long time,
Since it is a synthetic resin, it is durable without corrosion, and nonwoven fabrics made of long fibers are more suitable because their fiber length is superior to nonwoven fabrics made of staple-shaped short fibers on the order of cm or mm because of their superior surface friction resistance. It is adopted. The basis weight of the nonwoven fabric is preferably 30 to 200 g / m ^2, a basis weight 30 g / m
^When it is less than ² , the mechanical strength is remarkably reduced, the partial strength difference is large, the production efficiency is deteriorated as a tape-like yarn, and the mechanical strength as a covering material is insufficient. on the other hand,
If the basis weight exceeds 200 g / m ² , it is unsuitable because of its weight and lack of flexibility, which may hinder handling.

[0011] Such a nonwoven fabric is obtained by randomly depositing and bonding long fibers by a direct spinning method in which spinning, drawing, opening, and bonding steps are continuously performed.
Specifically, a non-woven fabric by a spun bond method in which a spinnable thermoplastic synthetic resin is put into an extruder to be in a molten state, and a fiber extruded from a spinning nozzle is drawn into a fiber by a roller method or an air jet method, Non-woven fabric by melt-blowing method in which the resin in the state is jetted from a spinning nozzle together with a high-pressure gas flow to form drawn fibers, or a solution in which a spinnable thermoplastic synthetic resin is dissolved in a solvent under high temperature and high pressure is released to the atmosphere through a spinning nozzle. Non-woven fabrics formed by flash spinning, in which the solvent is vaporized to form fibers, are exemplified. However, non-woven fabrics formed by flash spinning are particularly suitable in that they have high strength and are easy to handle as tape-like yarns.

In the flash spinning method, a solution obtained by dissolving a synthetic resin such as high-density polyethylene or polypropylene in a solvent having a low boiling point such as a halogenated hydrocarbon, an aromatic hydrocarbon, or an aliphatic hydrocarbon under high temperature and high pressure is used. It is released into the atmosphere at low temperature and low pressure through a spinning nozzle equipped with a pressure drop chamber in a more pressurized state, and the solvent evaporates instantaneously, giving the fiber orientation by its expansion force. An ultrafine and high-strength fiber having a single-fiber fineness of about 0.1 to 0.3 dr is formed, and the nonwoven fabric obtained by depositing the fibers while crossing each other and thermocompression bonding has a dense structure joined at a high density.

This non-woven fabric is formed by depositing and joining long fibers at a high density, so that it is opaque and has a high degree of whitening. However, it is preferable that the non-woven fabric has a light absorption rate of 5% or less as a light spectral characteristic. . That is, since the light absorption rate is as low as 5% or less as a constituent member of the light shielding net, the nonwoven fabric itself is less likely to accumulate heat, and an abnormal temperature rise inside the light shielding net can be suppressed.

The nonwoven fabric is formed into a tape-like thread by slitting a large number of grooves between a grooved roll or two guide rolls with a cutter blade or a round blade to a predetermined width. The slit width is 2 to 30 mm width, preferably 4 to 20
mm width. If it is less than 2 mm, the handling strength and practical strength as a tape-like yarn and a net structure will be insufficient. On the other hand, if it is larger than 30 mm, the balance of the process of the shading net will be remarkably deteriorated, making it practically difficult to handle.

[0015] The net base fabric used in the present invention is constituted by using a monofilament or a flat yarn for the weft.
Woven fabrics such as plain weave, twill weave, entangled weave, knitted fabrics such as Russell knit, tricot knit, and Miranese knit, or a group of many monofilaments or flat yarns arranged substantially in parallel at regular intervals are orthogonal to each other. And a laminated non-woven fabric or the like which is integrated by overlapping.

[0016] Since such a net base fabric is formed by laminating the tape-like yarn made of the above-mentioned non-woven fabric by heat fusion, it is used as a monofilament or a flat yarn in the construction of the net base fabric from a high melting polymer and a low melting polymer. Composite yarn is preferably used. Specifically, a monofilament having a core-in-sheath structure obtained by heating and stretching a composite filament, which is formed by extruding and cooling a composite filament from a nozzle in a molten state by positioning a high melting point polymer in a core layer and a low melting point polymer in a sheath layer, and a core, The multi-layer flat yarn obtained by extruding and cooling the multilayer film with a high melting point polymer and both outer layers as a low melting point polymer from a multilayer die in the molten state, shredding and heating and stretching several times. is there.

These composite yarns are laminated by laminating tape-like yarns, and then heat-pressed at a predetermined temperature, so that the intersections of the wefts are firmly joined with the low melting point polymer of the composite yarns and with the high melting point polymer. It will retain the strength, the resulting net base fabric has no gaps, there is little difference in porosity, and has excellent flexibility as a relatively smooth sheet body,
In addition, even if it is cut, the surroundings do not fray.

According to the present invention, a light-shielding net is formed by heat-sealing a tape-like thread made of the above-mentioned nonwoven fabric on at least one surface of a net base fabric at intervals. The light-shielding net needs to be formed so as to have a porosity of approximately 10 to 70%, although it varies depending on the object to be covered, the time of use, and the method of use. In other words, if the porosity is less than 10%, the air permeability may be impaired and the temperature of the interior covered with the light-shielding net may rise, and if the porosity exceeds 70%, the cold protection and frost protection are insufficient. Become. A more preferable range of the porosity is 20 to 60%, and the sizes of the individual cavities may be irregular.

[0019]

1 and 2 show the structure of a light shielding net according to this embodiment. The light-shielding net 1 is obtained by further heat-sealing a tape-like thread 2 to one side of a net base cloth 4 in which the flat yarns 3, 3 are arranged and cross-welded in a mesh manner. Net base fabric 4 made of plain woven mesh fabric using flat yarn 3 as warp yarn
May be used. Further, a tape-like thread may be heat-sealed on both sides of the net base fabric. These specific examples are described below.

Example 1 As a nonwoven fabric, a nonwoven fabric having a basis weight of 58 g / m ² produced by fiberizing high-density polyethylene by a flash spinning method was selected.
The tape was passed through a slitter provided with a cassette having a cutter blade attached to a 15 mm-wide distance piece between two guide rolls, and wound up as a 15 mm-wide tape-like thread 2. The spectral characteristics of this nonwoven fabric were measured using a Leica optical energy analyzer with an integrating sphere.
The reflectance (%) and the transmittance (%) were determined as an average value of 700700 nm, and the absorbance calculated by subtracting the reflectance and the transmittance from 100 was 1.87%.

On the other hand, the net base cloth 4 was prepared as follows. High density polyethylene (density = 0.956 g / cm ³ , MFR =
1.0 g / 10 min.) As the core layer 5, and low-density polyethylene (density = 0.924 g / cm ³ , MFR = 3.0 g / 10 min.) On both sides of the core layer 5.
As a method, a multilayer film having a three-layer structure is manufactured by co-extrusion inflation molding, and after slitting the film into a narrow width, by a hot plate contact type stretching method, a stretching temperature of 110 ° C. and a stretching ratio of 5.2 times in a longitudinal uniaxial direction. It was stretched and oriented, and subjected to an annealing treatment at 115 ° C. to form a flat yarn 3 having a three-layer structure with a fineness of 700 dr. FIG. 3 shows the structure of the flat yarn 3.

Next, a plurality of the above-mentioned tape-like yarns 2 each having a width of 15 mm, which are arranged substantially in parallel at intervals of 9 mm, form a group of warp-direction yarns. After being superimposed on the surface of the net base cloth 4 arranged in the course of the process, it is press-bonded with a metal roll heated to 120 ° C., and the intersection of the processes is fused and integrated to form the light-shielding net 1 shown in FIGS. did. The porosity of the shading net of Example 1 is
25%.

Example 2 A non-woven fabric having a basis weight of 75 g / m ² produced from a composite filament having a core of polyester and a sheath of polyethylene by a spunbond spinning method was selected. A tape-like yarn 2 having a width of 4 mm and a flat woven net base cloth composed of warp yarns of a flat yarn 3 having a three-layer structure, and 0.5
3 are drawn to each other at an interval of ~ 1 mm, and the three are taken as a unit at an interval of 5 mm, alternately superimposed on the front surface and the back surface of the plain woven net base fabric, and then fused and integrated. The light shielding net shown in FIG. As for the spectral characteristics of the nonwoven fabric used here, the absorptance was 3.56%.

Example 3 A 6 mm wide tape-like thread 2 made from the nonwoven fabric shown in Example 1 was used as warp and arranged in parallel so that there was a space of about 4 mm, and this was aligned with 3 mm. Flat yarn 3 of width
The light-shielding net of Example 3 was obtained by using the net base cloth 4 made of a 3 mm-spaced plain-woven mesh fabric.

COMPARATIVE EXAMPLE On a biaxially stretched high-density polyethylene film having a thickness of 40 μm, an aluminum vapor-deposited layer of about 600 Å was formed by a conventional method, and a low-density polyethylene film having a thickness of 25 μm was further formed on the vapor-deposited layer by a melt extrusion lamination method. After forming, the laminate was slit to obtain a vapor-deposited flat yarn having a width of 15 mm. The obtained vapor-deposited flat yarn was replaced with the tape-shaped yarn used in Example 1, and the other conditions were the same as in Example 1 except that a light-shielding net was used and a comparative example was used. In addition, the spectral characteristics of the aluminum vapor-deposited film used in the comparative example were such that the absorption rate was 1
2.78%.

Evaluation method Using a synthetic resin rod, arched frames having a width of about 1.2 m and a height of 0.8 m were formed, arranged at 0.8 m intervals, completely covered with a light-shielding net, and about 10 m long. Created a tunnel. The temperature near the top of the tunnel was measured, and the temperature change over time is shown in FIG. As a reference value for the temperature change, the change in the outside air temperature was added.

From FIG. 6, it can be seen that in Examples 1, 2, 3, and Comparative Example, the temperature of the inside of the tunnel is more efficiently increased in spite of the fact that the porosity is substantially the same as the light-shielding net. It can be seen that it can be suppressed. In addition, as a coating material,
When the state after use for about 3 months was observed, the light-shielding net of the example had a slight degree of dirt adhered to the surface and no change was observed. Many areas where glossiness or loss of gloss due to whitening were observed, and it was clear that durability was poor.

Compared with a polyolefin-based aluminum vapor-deposited film which is conventionally considered to have excellent heat insulating properties, the light shielding net of the present invention suppresses the temperature rise in the tunnel because of its high light reflectance and light absorption. It's low. In particular, the difference becomes large in a long wavelength portion related to heat. FIG. 7 shows the relationship between the light reflectance and the wavelength, and FIG. 8 shows the relationship between the light absorption and the wavelength. The light-shielding net of the present invention has a light absorptivity of almost 2% or less in the entire wavelength range, does not accumulate heat itself, and exhibits the effect of lowering the temperature as shown in FIG. .

[0029]

The light-shielding net of the present invention is composed of a tape-like thread obtained by slitting a non-woven fabric made of synthetic resin long fiber filaments and a net base cloth, and thus has excellent durability and weather resistance. Further, since the light absorption rate is small, the degree of heat storage is low, the strong heat of the sun is reflected, and the light passes through softly, so that "brightness" and "coolness" can be fully experienced. Therefore, it is particularly effective for use for the purpose of heat shielding and light shielding in a high temperature period in summer, and is useful as a covering material capable of creating a comfortable environment in the field of agriculture or livestock. .

Furthermore, the light-shielding net itself has excellent heat-sealing properties, is easy to heat-seam the net continuously, and is easy to perform synthetic resin eyelet processing. Also, if both the tape-like thread and the net base fabric are made of the same polyolefin-based resin, the material is recyclable and becomes carbon dioxide and water even when incinerated, and is a pollution-free and environmentally friendly material.

[Brief description of the drawings]

FIG. 1 is a partial plan view of a light shielding net of the present embodiment.

FIG. 2 is a partial cross-sectional view of the light shielding net of the present embodiment.

FIG. 3 is a partial sectional view of a flat yarn having a three-layer structure used in the present embodiment.

FIG. 4 is a partial plan view showing another embodiment.

FIG. 5 is a partial sectional view showing another embodiment.

FIG. 6 is a graph of a temperature change in a tunnel space covered with a light-shielding net of an example and a comparative example.

FIG. 7 is a graph showing the relationship between light reflectance and wavelength.

FIG. 8 is a graph showing a relationship between a light absorption rate and a wavelength.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Shading net 2 Tape thread 3 Flat yarn 4 Net base cloth 5 Core layer 6 Outer layer

──────────────────────────────────────────────────続 き Continued on front page (51) Int.Cl. ⁶ Identification code FI // D04H 3/00 D04H 3/00 C

Claims (1)

[Claims] 1. A tape-like yarn in which a nonwoven fabric in which synthetic resin long fiber filaments are deposited and bonded in a non-directional manner is slit into a narrow width, and a flat yarn or filament of synthetic resin is woven or intersected. A light-shielding net obtained by heat-sealing at least one surface of a net base fabric obtained by the method with an interval.