JP2006055002A - Sheet for preventing high-temperature injury to crop - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sheet for preventing high-temperature injury to crops having a high transmittance of visible rays to block heat rays so as to prevent high-temperature injury to crops without spoiling the growth of the crops. <P>SOLUTION: The sheet for preventing high-temperature injury to crops is formed so that thermoplastic resin uniaxial drawing yarns vertically and horizontally cross one another, and comprises a cloth-like body having a porosity of 5-80% shown in the following formula: porosity (%)=[(A×B)/(25.4×25.4)]×100, wherein A=25.4-(the number of warp (/25.4mm)×tape width (mm)), and B=25.4-(the number of weft (/25.4mm)×tape width (mm)). The uniaxial drawing yarns respectively contain inorganic powder having small shielding power against visible rays each with a wavelength of 400-780 nm and large shielding power against near-infrared rays each with a wavelength of 780-2,000 nm. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a high-temperature damage prevention sheet for crops, and more particularly, to a sheet that has high visible light transmittance, does not inhibit crop growth, and blocks heat rays to prevent high-temperature damage to cultivated crops.

  In the cultivation of crops in the agricultural field, there is a problem that high temperature damage occurs in the crops due to strong sunlight irradiation during the summer, resulting in a decrease in yield or quality. For this reason, in the summer, a sunshade sheet is used to block sunlight.

  However, when covering the sun, the heat rays composed of infrared rays and near-infrared rays are blocked, and at the same time, the visible light necessary for the crops is also blocked.

  For this reason, in Patent Document 1, it is proposed to cover a sun cover made of a thermoplastic resin to which lanthanum hexaboride or antimony-containing tin oxide is added as a light absorbing material. Lanthanum hexaboride or antimony-containing tin oxide has high visible light transmittance, and has a high blocking effect on infrared and near infrared rays. Therefore, it is said that high temperature damage can be prevented without inhibiting crop growth.

  However, in this document, a thermoplastic resin to which a powder that absorbs infrared rays and near infrared rays is added is formed into a film shape or a board shape and used as a sunshade. However, when covering crops in the form of film or sheet, the inside of the sunshade becomes difficult to ventilate, and therefore, even if the amount of permeation of heat rays is reduced, hot air stays inside the sunshade and the atmosphere of the crop Since the temperature becomes too high, there is still a problem that high temperature damage occurs in the crop.

For this reason, it is desired to develop an agricultural sheet that has good visible light transmittance, does not inhibit crop growth, and can efficiently avoid high-temperature damage.
JP 2004-141051 A JP2004-65004 JP 2003-38041 A

  The present invention provides a high-temperature damage prevention sheet for crops, which has a high visible light transmittance and can block heat rays and prevent high-temperature damage to crops without inhibiting crop growth.

The present invention has been made as a result of intensive studies to solve the above-mentioned problems. Specifically, the uniaxially stretched yarn of a thermoplastic resin is formed by intersecting vertically and horizontally, and is represented by the following formula (1). Consists of a cloth-like body having a porosity of 5 to 80%, and the uniaxially stretched yarn contains an inorganic powder having a small visible light shielding power with a wavelength of 400 to 780 nm and a large near infrared shielding power with a wavelength of 780 to 2000 nm. A high temperature damage prevention sheet for crops is provided.

  In addition, the present invention provides the above-mentioned crop high-temperature failure prevention sheet, cloth, in which the cloth-like body has a cumulative near-infrared transmittance of 780-1200 nm in wavelength that is 10% or more lower than that of visible light having a wavelength of 400-780 nm. The high temperature failure prevention sheet of the above crop, the inorganic powder is lanthanum hexaboride, whose accumulated body has a cumulative transmittance of near infrared rays having a wavelength of 1200 to 2000 nm that is 10% or more lower than that of visible rays having a wavelength of 400 to 780 nm Indium tin oxide, antimony tin oxide, or a mixture of two or more of the above-mentioned crops for preventing high-temperature damage, a bonding layer comprising a thermoplastic resin having a melting point lower than the base layer on at least one side of the base layer The tape-shaped uniaxially stretched yarns laminated with each other are crossed vertically and horizontally, and the intersections are heat-sealed. A base layer made of polyethylene or polypropylene and a bonding layer made of one or more selected from low density polyethylene, linear low density polyethylene, ethylene / propylene copolymer and ethylene / vinyl acetate copolymer are laminated. The above-mentioned high temperature failure prevention sheet for crops is provided.

  The high temperature damage prevention sheet for crops of the present invention is strong and excellent in durability, has a high visible light transmittance and excellent crop growth, and blocks heat rays to prevent high temperature damage of cultivated crops. Can do. Moreover, it has the effect | action which relieves cooling at night.

  As shown in FIG. 1, the crop high-temperature failure prevention sheet 1 of the present invention includes a cloth-like body 3 formed by using a uniaxially stretched yarn 2 uniaxially stretched with a thermoplastic resin having an effect of suppressing transmission of heat rays. Composed.

  In the present invention, the uniaxially stretched yarn 2 forming the high-temperature failure prevention sheet 1 broadly means a linear body that can form a sheet-like body, and is a linear body such as a tape-like body, a string-like body, a monofilament, a multifilament or the like These are twisted as necessary.

  The uniaxially stretched yarn 2 may have any structure. For example, as shown in FIG. 3A, a flat yarn formed into a tape shape by slitting a thermoplastic resin film to a predetermined width and uniaxially stretching. Further, as shown in FIG. 3B, a split yarn in which a number of cuts 5 and 5 are formed in a tape-like body can also be used. Furthermore, as shown in FIG. 3 (C), the tape-shaped body can be provided with ultra-thin longitudinal ribs 6 and 6, and by providing the rib 6, the reflected light of the sun is scattered and the influence on the environment is reduced. can do.

  In addition, the cross section can be a uniaxially drawn yarn 2 having a round shape, an oval shape, a square shape, a polygonal shape, or other irregular shape. Further, a mixture of different types of resins is extruded into a filament, and a gap between the resins is formed. It is possible to increase the suppleness by using a dumbline that is split and fibrillated. Moreover, one piece can be used alone as a woven yarn, and several pieces can be bundled and used.

  The uniaxially stretched yarn 2 may be a single layer as shown in FIG. 4 (A), or on one or both sides of the base layer 7 as shown in FIGS. 4 (B) and 4 (C). It can be set as the laminated uniaxially stretched yarn 2 in which the joining layer 8 made of a thermoplastic resin having a melting point lower than that of the base layer is formed. Further, the bonding layer 8 can have a seascore structure as shown in FIG. 4D and a side-by-side structure as shown in FIG.

  As the thermoplastic resin constituting the monolayer of the uniaxially stretched yarn 2 or the base layer 7 of the laminate, a resin having a large stretching effect, generally a crystalline resin is used. Specifically, high-density polyethylene, medium density Polyolefins such as polyethylene, polypropylene, ethylene / α-olefin copolymers, olefin polymers such as ethylene / vinyl acetate copolymers, polyesters such as polyethylene terephthalate and polybutylene terephthalate, polyamides such as nylon 6 and nylon 66, acrylonitrile, vinylon Etc. can be used. Of these, olefin polymers such as high-density polyethylene, medium-density polyethylene, linear low-density polyethylene, and polypropylene are desirable from the viewpoint of processability and economy.

  The joining layer 8 joins the uniaxially stretched yarns 2 after the uniaxially stretched yarns 2 are woven, and is made of a thermoplastic resin having a lower melting point than that of the thermoplastic resin constituting the base layer 7 and having an excellent heat fusion property. Used.

  Specifically, olefins such as high-pressure low-density polyethylene, linear low-density polyethylene, high-density polyethylene, polypropylene, ethylene / propylene copolymer, ethylene / α-olefin copolymer, ethylene / vinyl acetate copolymer, etc. Polymers, polyesters such as polyethylene terephthalate and polybutylene terephthalate, polyamides such as nylon 6 and nylon 66 can be used, and the melting point of the base layer is lower than that of the base layer, preferably 20 ° C. or higher. A plastic resin is selected. In particular, olefin polymers such as high-pressure method low-density polyethylene, high-density polyethylene, linear low-density polyethylene, and polypropylene are desirable, and linear low-density polyethylene polymerized using a metallocene catalyst is particularly preferable.

  Furthermore, an inorganic powder serving as a heat ray transmission preventing material for shielding heat rays is added to the thermoplastic resin forming the uniaxially stretched yarn 2.

  As the inorganic powder serving as the heat ray transmission preventing material, a powder having a small visible light shielding power with a wavelength of 400 to 780 nm and a large near infrared shielding power within a wavelength range of 780 to 2000 nm is used. Inorganic powders include those that exhibit large absorption in the wavelength range of 780 to 1200 nm and those that exhibit large absorption in the range of 1200 to 2000 nm, and any of them can be used.

  Specifically, glass powder such as soda glass, shelf silicate glass, lead glass, silica, hydrotalcite, lanthanum hexaboride, indium tin oxide, or antimony tin oxide can be used. Lanthanum, indium tin oxide, or antimony tin oxide is preferred. The inorganic filler is a powder of 1 μm or less, preferably 0.5 μm or less. When the particle diameter is 1 μm or less, the increase in HAZE of the uniaxially stretched yarn 2 is suppressed, and transparency can be maintained. The blending amount is usually 0.05 to 50% by weight, preferably 0.1 to 30% by weight.

  The thermoplastic synthetic resin that forms the uniaxially stretched yarn 2 can be blended with various additives as necessary. Examples thereof include phenols, organic phosphites, phosphines and other organic phosphorus, thioethers, and the like. Antioxidants; Light stabilizers such as hindered amines; Ultraviolet absorbers such as benzophenones, benzotriazoles, and benzoates; Antistatic agents; Dispersants such as bisamides, waxes, and organometallic salts; Alkaline earth metals Chlorine scavengers such as carboxylates of salts; Lubricants such as amides, waxes, organometallic salts, and esters; Metal deactivators such as hydrazines and amine acids; Bromine-containing organics, phosphoric acids, etc. Inorganic and organic antibacterial agents such as metal pigments, organic pigments, inorganic pigments, and metal ions can be added.

  These additives are appropriately combined and blended in any step of manufacturing the material composition of the base layer 7 and the bonding layer 8. The blending of the additive may be prepared by mixing at a predetermined ratio using a kneading device such as a conventional known twin screw extruder, Banbury mixer, kneader, mixing roll, and melt-kneading the mixture. A so-called master batch having a high concentration may be prepared and used after being diluted.

  When the laminated uniaxially drawn yarn 2 is used, as a means for forming a laminated film that becomes a molding material of a laminated flat yarn or a laminated split yarn, a film that becomes the base layer 7 and a film that becomes the bonding layer 8 are formed in advance. Means for forming a multilayer using a dry laminating method or a thermal laminating method, a method of coating a thermoplastic resin to be the bonding layer 8 on the surface of the film to be the base layer 7, a bonding layer 8 to the film to be the base layer 7 formed in advance. Any known means such as extrusion laminating or extrusion molding as a laminated film by multilayer coextrusion may be appropriately selected and used. Ease of molding and cost, and adhesion between each layer of the product In this respect, a method of obtaining a laminated body of the base layer 7 and the bonding layer 8 in one step by a multilayer coextrusion method is desirable. The seascore structure or side-by-side structure is generally based on a coextrusion method.

  Further, as a means for drawing the uniaxially drawn yarn 2, a film that becomes the base layer 7 may be drawn in a uniaxial direction, and then a thermoplastic resin that becomes the bonding layer 8 may be laminated, and this may be slit into a tape shape. Alternatively, it can be obtained by stretching in a uniaxial direction before or after slitting the laminated film in which the base layer 7 and the bonding layer 8 are laminated. The draw ratio is usually about 3 to 10 times.

  The thickness of the uniaxially stretched yarn 2 is not limited in any way and can be arbitrarily set according to the purpose, but is generally 50 to 10,000 decitex, preferably 100 to 5000 decitex. In the case of a tape shape, the yarn width is 0.3 to 200 mm, preferably 0.5 to 100 mm, and the yarn thickness is 5 to 500 μm.

  When the layer structure of the elongated filament 2 is a three-layer structure, generally, the thickness composition ratio is set as bonding layer: base layer: bonding layer = 1: 98: 1 to 25:50:25.

  As shown in FIGS. 1 (A) and 1 (B), the drawn filament 2 thus obtained can be woven into a plain weave to form a cloth-like body 3. In addition, it can be made into a cloth-like body 3 by weaving in a twill weave, a twill weave, a knit weave, a double weave, a double weave, a knit weave, etc. It is also possible to make a cloth-like body. As a loom for weaving, a known loom such as a circular loom, a slewer loom, a water jet loom can be used. Further, as shown in FIG. 2, a plurality of elongated filaments 2b are arranged in parallel, and another elongated filament 2a is arranged in parallel in the direction intersecting with the elongated filament 2b, and the intersection is thermally bonded. It can be set as the cloth-like body 3 which consists of the cross-bonded cloth (soft).

The cloth-like body 3 has a porosity shown by the following formula (1) of 5 to 80%, preferably 10 to 60%. If it is less than 5%, it is difficult to avoid a temperature rise inside the covered sheet, and if it exceeds 80%, the effect of preventing the high-temperature failure is deteriorated because the heat ray blocking effect is lowered.

  In this invention, when it forms in cloth shape and it is set as the high temperature failure prevention sheet | seat 1, with respect to the accumulated transmittance | permeability of visible light with a wavelength of 400-780 nm, the accumulation of near infrared rays with a wavelength of 780-1200 nm or 1200-2000 nm. It is desirable that the transmittance be 10% or more, preferably 20% or more.

  The light transmittance is controlled by adjusting the amount of inorganic powder added to the base layer 7 or the bonding layer 8 constituting the uniaxially stretched yarn 2, the fineness of the uniaxially stretched yarn 2, the number of warp yarns driven, and the like. be able to.

Example 1
1. Flat yarn High density polyethylene (density 0.956 g / cm ³ , melting point 132 ° C.) containing 0.2% by weight of lanthanum hexaboride fine particles having an average particle size of 0.1 μm is used as an intermediate layer, and low density polyethylene (density 0. A blown film having a bonding layer of 922 g / cm ³ and a melting point of 113 ° C. was formed, slit to a predetermined width, stretched 7.2 times at 100 ° C. with a hot plate, and then 6% at 110 ° C. with a hot air oven. A loose yarn of 400 dt and a width of 1 mm was formed.
2. Weaving Using the above flat yarns for warp and weft yarns, weaving the warp and weft density to 8 / 25mm each with a slewer loom, and then heat-sealing the intersections of the yarns with a 120 ° C hot roll, A woven fabric having a porosity of 47% was obtained.

Example 2
A woven fabric was obtained in the same manner as in Example 1 except that 5% by weight of antimony tin oxide was dispersed in place of the inorganic powder instead of the lanthanum hexaboride fine particles.

Comparative Example 1
A woven fabric was obtained in the same manner as in Example 1 except that the inorganic powder was not dispersed in the intermediate layer.

  About the woven fabric obtained by the above method, the cumulative transmittance of each light beam having a wavelength of 400 to 780 nm, 780 to 1200 nm, and 1200 to 2000 nm is measured, and the outdoor ground is covered in a tunnel shape with the obtained woven fabric. Then, the change in the ground temperature was measured, and the maximum temperature difference with respect to the uncovered state was measured within one day. The results are shown in Table 1.

  The HAZE (JIS-K7105 haze value) before and after stretching of the uniaxially stretched yarn obtained by the above method was measured, and the results are shown in Table 2.

  The high-temperature damage prevention sheet of the present invention crop can be used as a tunnel cover, a house-type cover, or a curtain in a house as a sun cover in crop cultivation, and because the present invention sheet has excellent durability, It can also be used as a sandproof, dustproof, windproof net, etc.

(A) which shows an example of the high temperature failure prevention sheet of this invention crop is a top view, (B) is a longitudinal cross-sectional view The longitudinal cross-sectional view which shows the other example of the high temperature failure prevention sheet | seat of this invention crop (A)-(C) is a perspective view showing an example of a uniaxially stretched yarn Longitudinal sectional view showing an example of uniaxially drawn yarn

Explanation of symbols

1. 1. High temperature damage prevention sheet for crops Uniaxially drawn yarn 4. Cloth-like body Break 6. Rib 7. Base layer 8. Bonding layer

Claims (6)

A uniaxially stretched yarn of a thermoplastic resin is formed by crossing vertically and horizontally, and is made of a cloth-like body having a porosity represented by the following formula (1) of 5 to 80%, and the uniaxially stretched yarn has a wavelength of 400 to 780 nm. A high-temperature damage prevention sheet for crops, comprising an inorganic powder having a small visible light shielding power and a large near-infrared shielding power with a wavelength of 780 to 2000 nm.

  The high temperature failure prevention sheet for crops according to claim 1, wherein the cloth-like body has a cumulative transmittance of near infrared rays having a wavelength of 780 to 1200 nm lower by 10% or more than a cumulative transmittance of visible rays having a wavelength of 400 to 780 nm.   The high temperature damage prevention sheet for crops according to claim 1, wherein the cloth-like body has a cumulative transmittance of near infrared rays having a wavelength of 1200 to 2000 nm that is 10% or more lower than a cumulative transmittance of visible rays having a wavelength of 400 to 780 nm.   The high-temperature disorder prevention sheet for crops according to any one of claims 1 to 3, wherein the inorganic powder is lanthanum hexaboride, indium tin oxide, or a simple substance or a mixture of two or more kinds of antimony tin oxide.   The cloth-like body is formed by crossing longitudinally and transversely tape-shaped uniaxially stretched yarns in which a joining layer made of a thermoplastic resin having a melting point lower than that of the base layer is laminated on at least one side of the base layer, and the intersection is thermally fused. The high temperature disorder | damage | failure prevention sheet | seat of the crop in any one of -4.   The uniaxially drawn yarn comprises a base layer made of high-density polyethylene or polypropylene and one or more selected from low-density polyethylene, linear low-density polyethylene, ethylene / propylene copolymer, and ethylene / vinyl acetate copolymer. The crop high-temperature failure prevention sheet according to claim 5, wherein the bonding layer is laminated.

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