JPH09157992A - Sheet for agriculture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject sheet specified in basis weight, space degree and tear strength, respectively, capable of improving the yield of agricultural crops and good in handleability by using conjugate yarns whose outer layers are formed from a low melting point component, such as conjugate flat yarns, as at least one of warps and wefts and subsequently termally fusing the crossed parts of the warps with the wefts. SOLUTION: Conjugate yarns 1 are arranged as warps and/or as wefts in a meshed sheet, and the warp-weft crossed parts of the meshed sheet are thermally fused to fix the crossed parts. The conjugate yarns 1 comprise conjugate flat yarns or conjugate filaments whose outer layers 3 are formed from a low melting point component and whose core layers 2 are also formed from a higher melting point thermoplastic resin by 10-35 deg.C than the melting point of the low melting point component. The formed meshed sheet has a basis weight of 15-50g/m<2> , a space degree of 5-60% and a tear strength of >=3kg, is excellent in mechanical strengths, and has proper light transmission, gas permeability and heat insulation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to open field cultivation, tunnel cultivation, for covering agricultural crops for the purpose of heat retention, frost prevention, and light shielding.
The present invention relates to an agricultural sheet used for house cultivation and the like.

[0002]

2. Description of the Related Art Conventionally, a bamboo sheet or a gauze cloth has been used as an agricultural sheet for the purpose of keeping warm in the winter and shading in the summer. In recent years, however, non-woven fabrics and woven fabrics made of synthetic resin fibers have been used instead of them. Sheets using knitted cloth are used, for example, made of hydrophobic fiber of 6 denier or more and having a basis weight.
Agricultural covering material for solids made of non-woven fabric of 10 to 30 g / m ² and a light transmittance of 85% or more (Japanese Utility Model Publication No. 4-8769), and long fibers having a denier of 0.1 to 15 denier. 5 per area
A non-woven fabric deposited at a rate of up to 30 g / m ² and one layer of thermoplastic yarn having a diameter of 200 μm or more at intervals of at least 5 mm is laminated on the weft or the bias for covering agricultural products (Japanese Patent Laid-Open No. 3-76).
513) or a slitting or splitting yarn made of ethylene-vinyl alcohol copolymer resin as a warp and / or weft as a frost-preventing coating material (Japanese Utility Model Publication No. 62-64783). ) Etc. are disclosed.

Agricultural sheets made of non-woven fabrics are lightweight and easy to handle, but have poor mechanical strength. In particular, weak tear strength poses a problem, and the sheets are torn by strong winds or eyelets. There is a problem that the strength is not expressed and it is difficult to apply the sheet, and when the thickness of the sheet is increased to enhance the tear strength, the weight also increases and the light transmittance decreases.

Agricultural sheets made of knitted or woven fabric, which have coarse stitches, move at the intersections of the longitudinal and lateral directions to cause eye gaps during the spreading work or the handling such as opening / closing for temperature control. Disadvantages such as turbulence and partial difference in porosity and change in sheet size have been pointed out.In addition, those with dense stitches have large sheet thickness, heavy weight and poor flexibility. However, there is a problem that the price is high.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a sheet body which has excellent mechanical strength and is easy to handle, and which has a certain level of light transmission, breathability and heat retention. It is to improve the yield of agricultural products and provide an inexpensive agricultural sheet.

[0006]

DISCLOSURE OF THE INVENTION The present invention provides a mesh body constituted by using a composite yarn having a core layer made of a high melting point component and an outer layer made of a low melting point component in at least one of the warp and weft. there, the amount of basis is history intersection the sealing process by heat-sealing is performed 15 to 50 g / m ^2, porosity of 5% to 60%, tear strength 3
An agricultural sheet characterized by having a weight of at least kg.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The agricultural sheet of the present invention is a mesh body having a mesh in the form of a woven fabric, a knitted fabric or a non-woven fabric using a composite yarn composed of a high melting point component and a low melting point component. is there.

The composite yarn is composed of a core layer having a high melting point component and an outer layer having a low melting point component. Specifically, the composite yarn is coextrusion laminated by a multi-layer T-die flat method or an inflation method. Alternatively, a composite flat yarn (shown in FIG. 1 (a)) obtained by chopping a three-layer film composed of a core layer and both outer layers laminated by a sequential extrusion laminating method and then longitudinally uniaxially stretching it, or. An example is a composite monofilament (shown in FIG. 1 (b)) obtained by extruding in a molten state from a multi-layer nozzle in a core-sheath structure, cooling, and uniaxially stretching in the longitudinal direction.

As the synthetic resin forming each layer of the composite yarn, a thermoplastic resin corresponds to stable quality and continuous productivity, and examples of the thermoplastic resin having a high melting point component as a core layer include polypropylene and high density polyethylene. , Polyester, polyamide, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polystyrene, polyacrylonitrile, and copolymers belonging to these series are typical examples. Here, the thermoplastic resin of the low melting point component to be the outer layer is more than the thermoplastic resin of the high melting point component, the melting point is 10 to 35 ℃, preferably 15 to 30 ℃ lower resin is selected, for example, Ultra-low-density polyethylene, low-density polyethylene, linear low-density polyethylene, ethylene / α-olefin copolymer composed of ethylene and α-olefin having 3 or more carbon atoms produced using a metallocene catalyst, ethylene-vinyl acetate Examples thereof include copolymers and ethylene-acrylic acid copolymers.

The composition ratio of the high melting point component and the low melting point component is preferably 90 / in terms of the weight ratio of the high melting point component / the low melting point component.
It is 10 to 50/50, more preferably 80/20 to 60/40. That is, when the composition ratio of the high-melting point component is less than 50% by weight, sufficient strength as a composite yarn cannot be obtained, while when the composition ratio of the low-melting point component is less than 10% by weight, the crossing portion due to heat fusion described later is formed. It is not preferable because the sealing effect is insufficient.

The fineness of the composite yarn is preferably 50 to 1,000 dr, more preferably 150 to 500 dr. That is, fineness
If it is less than 50dr, it is not strong and is inferior in durability as a constituent member of an agricultural sheet, while if it exceeds 1000dr, the sheet is
It is inferior in flexibility and becomes a problem. In the composite yarn, it is preferable that the tape width of the flat yarn shape is 1 to 6 mm, or the diameter of the monofilament shape is 0.1 to 1 mm.

A mesh body is formed by using this composite yarn, but its form and structure are not limited as long as it has appropriate air permeability and light shielding property when used as an agricultural sheet. , For example, plain weave, twill weave,
Tricot knitting, Milanese knitting, Russell knitting, etc. as knitted fabrics such as mottled weave and entangled weave.
An example is one in which a large number of arranged warp yarn groups and weft yarn groups are superposed using a non-woven fabric manufacturing apparatus disclosed in Japanese Laid-Open Patent Publication No. 657 or JP-A-58-180658. Further, the yarn driving intervals at both ends and the peripheral edge of the agricultural sheet may be made close, which further increases the strength and facilitates handling.

In the mesh body, it is most preferable to use the composite yarn for the warp yarn and the weft yarn for the heat fusion at the intersection, but it is also possible to use the composite yarn for only one of the warp yarn and the weft yarn. In other words, if one of the yarns forming the crossing direction is a composite yarn, the low-melting point component softens and melts and becomes a stop. Therefore, the yarns other than the composite yarn are made of a resin having a melting point equal to or higher than the low melting point component of the composite yarn,
The yarn obtained by spinning the thermoplastic resin exemplified as the above-mentioned high melting point component is preferably adopted.

The meshing process at the crossing portion of the mesh is carried out by a known heat treatment method such as a hot plate contact type, a heat roll type, an infrared irradiation type, a high frequency welder type and a hot air tenter type. it can. Here, the sealing process is performed in a temperature range that is equal to or lower than the melting point of the high-melting point component and is equal to or higher than the softening point of the low-melting point component, but the heat-sealing of the low-melting point component is performed without impairing the stretching effect of the high-melting point resin. It is essential to be seen.

The mesh thus obtained is used as an agricultural sheath.
When used as a sheet, it is necessary that the porosity, which is the ratio of the opening area due to the arrangement of the warp lines to the entire surface of the sheet, is 5 to 60%. That is, if the porosity is less than 5% in the dense mesh, the air flow rate is small and there is a risk of high temperature damage to the crops in summer. The purpose of frost and shading cannot be achieved. The size of the mesh one gap Mesuki portion, 0.2～40Mm ^2, preferably from be 1 to 20 mm ^2.

The basis weight of the mesh body should be 15 to 50 g / m ^2, and more preferably 20 to 35 g / m ² . That is, if the basis weight is less than 15 g / m ² , the form as a durable and strong mesh cannot be obtained, while if the basis weight exceeds 50 g / m ² , it is heavy as an agricultural sheet and poor in flexibility. Becomes

Further, regarding the strength of the mesh body, it is desirable that the tensile strength is 15 kg / 5 cm or more in both the longitudinal and longitudinal directions from the viewpoint of handleability as an agricultural sheet, but as a particularly important physical property, the tear strength is the longitudinal direction. It is necessary to weigh more than 3 kg. That is, if the tear strength is less than 3 kg, it is not possible to satisfy not only the strength required for normal spreading work as an agricultural sheet but also the strength that can withstand strong winds, and the peripheral edge portion of the sheet with weak tear strength. Eyelets cannot be placed on this, which causes problems such as difficulty in handling during work.

The agricultural sheet of the present invention contains an antioxidant, an ultraviolet absorber, a light stabilizer, a lubricant, an antistatic agent, a pigment, an inorganic filler, a flame retardant, a cross-linking agent, a foaming agent, in a resin component. Additives such as nucleating agents can be blended and used. In particular, the coloring is arbitrary according to the purpose, and when the translucency is important, no coloring is selected, when the heat retaining property and the light shielding property are important, the black color is selected, and when the light reflecting property is important, the silver color or the like is selected. In addition, aluminum vapor deposition yarns may be partially driven or knitted at predetermined intervals for the purpose of imparting insect repellency.

[0019]

【Example】

Example 1 A polypropylene having a melting point of 138 ° C. was used as a core layer, and an ethylene-acrylic acid copolymer having a melting point of 109 ° C. (AA content 10
%) Was slit and then stretched 5.8 times to obtain a composite flat yarn having a fineness of 300 dr and a width of 1.4 mm. Using this composite flat yarn as a warp and weft, weave a plain weave design with a striking density of 6 × 6 yarns / inch, then 11
A mesh body was formed by heat-sealing the crosswise and crossing portions by a 5 ° C hot plate contact-type welding method.

This mesh body was cut into a size of 2 × 5 m, and eyelets were formed at intervals of 40 cm on the folded edges where each peripheral portion was folded back with a width of 35 mm to obtain the agricultural sheet of Example 1.

Example 2 A high-density polyethylene having a melting point of 130 ° C. was used as a core layer, and a film having a three-layer structure having low-density polyethylene having a melting point of 112 ° C. as an outer layer was slit on both sides of the film, and the film was drawn 5.2 times to have a fineness of 3
A composite flat yarn having a width of 50 mm and a width of 1.5 mm was obtained. Using this composite flat yarn as a warp and weft, weave a plain weave design with a striking density of 8 × 8 yarns / inch, and then heat-bond the warp-weft crossing portion by a hot plate contact fusion method at 115 ° C. to form a mesh body. Done Others were the same as in Example 1.

Example 3 A high-density polyethylene having a melting point of 130 ° C. was used as a core layer, and an ethylene-vinyl acetate copolymer having a melting point of 108 ° C. (VA content 1
After slitting a three-layer polyethylene film having 5%) as an outer layer, it was drawn 5.5 times to obtain a composite flat yarn having a fineness of 500 dr and a width of 1.7 mm. Using this composite flat yarn as a warp and weft, weave with a plain weave design with a driving density of 8 × 8 yarns / inch,
Then, a mesh body was formed by heat-sealing the crosswise-latitude intersections by a hot plate contact type fusion method at 115 ° C. Others were the same as in Example 1.

Example 4 In Example 2, as a weft, a single-layer flat yarn made of high-density polyethylene having a melting point of 130 ° C. (fineness: 350 d
r, 1.5 mm width) was used.

Example 5 High-density polyethylene having a melting point of 130 ° C. was used as a core layer, and the melting point was 112 ° C.
The filament spun using the low density polyethylene as a sheath layer was drawn 6.2 times to obtain a composite monofilament having a fineness of 350 dr and a diameter of 0.22 mm. This composite monofilament was used in the same manner as in Example 2 except that the weft was used.

Example 6 In Example 2, a single-core monofilament made of high-density polyethylene having a melting point of 130 ° C. as a weft (fineness: 350 d
r, diameter 0.22 mm) was used.

Comparative Example 1 The same procedure as in Example 2 was carried out, except that the composite monofilament used in Example 5 was used together with the warp and weft to form a plain weave design with a driving density of 24 × 24 filaments / inch. .

COMPARATIVE EXAMPLE 2 The same procedure as in Example 2 was carried out except that the number of driving was 16 × 16 / inch.

Evaluation The physical properties of the mesh sheets that became the agricultural sheets of Examples and Comparative Examples were measured and summarized in Table 1. In addition, the tensile strength in the table is a measured value based on JIS 1096 A method, and the tear strength is a measured value based on JIS L1096 A-1 method.

[0029]

[Table 1]

The agricultural sheet of the example was used as a covering material for open field cultivation of spinach for about 5 months from October to March, and the spinach grew smoothly in 45 days from sowing to harvesting. However, the light transmission effect and the heat retention effect were sufficient.
After that, when about 4 months from May to September was used as a coating material for Komatsuna, Komatsuna grew well in 50 days from sowing to harvesting, and the shading effect and ventilation effect were sufficient. . Furthermore, the workability was extremely efficient with no damage during spreading, recovery, or relocation work due to repeated use.

Comparative Example 1 is heavy and lacks flexibility, is difficult to handle, and has a large porosity and is difficult to use for the purpose of heat retention and frost prevention. Comparative Example 2 has a low porosity and poor air permeability. Since it is likely to cause high temperature damage in summer and is difficult to use, there are problems in using it as an agricultural sheet, respectively.

[0032]

INDUSTRIAL APPLICABILITY As described above, the agricultural sheet of the present invention has a mesh in the form of a woven fabric, a knitted fabric or a non-woven fabric using a composite yarn composed of a high melting point component and a low melting point component. Since it is a mesh body, heat treatment is performed after the yarns are arranged, so that the low-melting point component covering the yarn surface is easily heat-sealed and strongly bonded at the crossing and crossing points, and The stretching effect is not impaired, the mechanical strength of the sheet is excellent, and the mesh body is not misaligned or deformed.

In addition, since the agricultural sheet is highly flexible, lightweight, and has an appropriate porosity, it is light-transmitting, light-shielding and aerating in cultivation methods such as greenhouse cultivation and open-air cultivation. It can be suitably used as a covering material for the purpose of heat resistance and heat retention. Furthermore, since the tear strength of the sheet is excellent, eyelets can be provided in the peripheral edge of the sheet, and the sheet hooking work can be efficiently performed.

[Brief description of the drawings]

FIG. 1 is a composite yarn constituting an agricultural sheet of the present invention, (a) is a flat yarn, and (b) is a schematic view of a cross section of a monofilament.

[Explanation of symbols]

 1 composite yarn 2 core layer 3 outer layer

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Claims (1)

[Claims] 1. A mesh body comprising a composite yarn in which a core layer is formed of a high melting point component and an outer layer is formed of a low melting point component in at least one of the warp and weft, and the crossing and weft crossing portion is made of heat. 15-50g / m ² basis weight, which has been subjected to sealing by fusion.
An agricultural sheet having a porosity of 5 to 60% and a tear strength of 3 kg or more.