Agricultural sheet, inner lining sheet, and inner lining curtain

Abstract

To provide a technology for agricultural facilities such as greenhouses that sufficiently collects visible light required for crop growth while preventing excessive temperature rise.SOLUTION: In an agricultural sheet 1, a band-shaped heat-shielding yarn 10 containing a heat-shielding agent and a band-shaped transparent yarn 20 containing no heat-shielding agent are aligned in parallel and connected by knitting with thread 30.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to an agricultural sheet, a lining sheet and a lining curtain. [Background technology]

[0002] Conventionally, indoor cultivation, in which crops are grown in agricultural facilities such as agricultural greenhouses, has been widely practiced. In indoor cultivation, it is necessary to ensure that the brightness inside the facility is suitable for the crops being grown and to maintain an optimum temperature for growth. As one of the technologies for achieving this, various proposals have been made regarding agricultural curtains (also called inner curtains) that are installed inside the greenhouse.

[0003] Agricultural netting and lining curtains for agricultural greenhouses that are highly effective in keeping warm in addition to providing light-shielding and heat-shielding properties have been proposed (see, for example, Patent Document 1). The agricultural netting disclosed in Patent Document 1 is made by weaving filaments into a net shape, and multiple light-shielding tapes formed to a desired width are arranged in parallel, with at least one side of the light-shielding tape being provided with a heat-reflecting portion that has a higher heat reflectance than the light-shielding tape.

[0004] Also, for the purpose of providing an agricultural covering material excellent in various properties such as breathability, heat retention, and ease of handling, and also having the desired light-transmitting properties, a covering material has been proposed which is made of a woven fabric in which warp threads made of tape-like yarns having a width of 1 to 20 mm are formed so as to have substantially no gaps in a plan view, and weft threads made of yarns having a diameter of 5 mm or less are formed at intervals of 0.5 to 30 mm, and in which linear synthetic resin layers containing a light-transmitting regulator are formed over 1 to 70 area % of the surface of the woven fabric by laminating in stripes (see, for example, Patent Document 2). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2020-80655 A [Patent Document 2] Patent No. 3763965 Summary of the Invention [Problem to be solved by the invention]

[0006] In agricultural greenhouses, if infrared rays penetrate too much, the temperature inside the greenhouse may rise significantly, making it an unsuitable growing environment for crops, in which case cooling by air conditioning or the like is required to suppress the temperature rise, resulting in an increase in fuel costs, etc. If inner curtains are installed to suppress the temperature rise as described above, there is an issue that the transmittance of high visible light that contributes to efficient plant growth decreases.

[0007] The present invention has been made in consideration of the above circumstances, and aims to provide technology that can suppress excessive temperature rise in agricultural facilities such as agricultural greenhouses while sufficiently taking in the visible light necessary for crop growth. [Means for solving the problem]

[0008] According to the present invention, the following techniques are provided. (1) An agricultural sheet in which a strip of heat-shielding yarn containing a heat-shielding agent and a strip of transparent yarn not containing a heat-shielding agent are arranged in parallel and connected by weaving with thread. (2) The agricultural sheet according to (1), wherein the weaving method using the yarn is a raschel weave. (3) The heat retention rate P measured using the "KES-F7 Thermo Lab II" measuring device manufactured by Kato Tech Co., Ltd. is 55% or more and 57% or less. The measuring device is A heater measuring 100mm in length and 100mm in width placed on top of insulation, A temperature sensor that measures a surface temperature of the heater; A space A having a length of 100 mm, a width of 100 mm, and a height of 5 mm is provided above the heater by a heat insulating spacer. a hollow test chamber having a length of 320 mm, a width of 460 mm, and a height of 110 mm, which accommodates the heater, the temperature sensor, and the space A; a wind tunnel having an inner diameter of 150 mm that is connected to the upper part of the test chamber through a communication port and is capable of introducing air into the test chamber; a fan that is provided in the wind tunnel and takes in outside air to supply the air to the space at a predetermined wind speed; The heater can be controlled to maintain a predetermined temperature by controlling the amount of power supplied by a temperature difference proportional voltage output method based on the measurement value of the temperature sensor, The distance between the space A and the communication port of the wind tunnel is 105 mm, The agricultural sheet according to claim 1 or 2, wherein a filter paper measuring 100 mm in length, 100 mm in width, and 0.26 mm in thickness is placed in a wet state on the surface of the heater, and a test piece obtained by cutting the agricultural sheet to 200 mm in top view and placing it on the upper surface of the spacer so as to cover the space A. In this state, air having a temperature of 20°C and a humidity of 65% is blown from the wind tunnel to the test piece at a wind speed of 0.3 m / sec while controlling the power supplied to the heater so as to maintain the surface temperature of the heater at 30°C based on the measurement value of the temperature sensor. The amount of power per minute when W is the amount of power per minute when the test piece is not placed is W0. The heat retention rate P is calculated by the following formula (1): P = (W0 - W) / W0 × 100 (%) (1) (4) The agricultural sheet according to any one of (1) to (3), having a light transmittance of 54% or more and 65% or less at a wavelength of 400 to 700 nm. (5) The agricultural sheet according to any one of (1) to (4), having a light transmittance of 43% or more and 65% or less at a wavelength of 700 to 1000 nm. (6) The agricultural sheet according to any one of (1) to (5), having a light transmittance of 52% or more and 65% or less at a wavelength of 600 to 700 nm. (7) The agricultural sheet according to any one of (1) to (6), wherein the heat insulating yarn contains titanium oxide-coated mica as the heat insulating agent. (8) The agricultural sheet according to any one of (1) to (7), wherein the heat-shielding yarns and the transparent yarns are arranged in a periodic pattern. (9) The agricultural sheet according to (8), wherein the ratio of the heat shielding yarn to the transparent yarn in the width direction is 1:1 to 5:1. (10) The agricultural sheet according to any one of (1) to (9), wherein the thickness ratio of the heat-shielding yarn to the transparent yarn is 1:1 to 5:1. (11) A lining sheet or lining curtain for use inside an agricultural greenhouse, the lining sheet or lining curtain being formed using the agricultural sheet according to any one of (1) to (10). Effect of the Invention

[0009] According to the present invention, it is possible to provide a technique that can prevent an excessive temperature rise in an agricultural greenhouse or the like while allowing a sufficient amount of visible light necessary for crop growth to be taken in. [Brief description of the drawings]

[0010] [Figure 1] FIG. 2 is a diagram showing a schematic diagram of an internal structure of an agricultural house according to an embodiment. [Diagram 2] 1 is a photographed image of an agricultural sheet according to an embodiment. [Diagram 3] FIG. 1 is a diagram showing a schematic diagram of an agricultural sheet according to an embodiment. [Figure 4] FIG. 1 is a diagram showing a schematic configuration of a measurement device for measuring a heat retention rate according to an embodiment. [Diagram 5] FIG. 2 is a diagram showing the inside of a test chamber of a measuring device according to an embodiment and the arrangement of test pieces. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] <Summary> An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing a schematic diagram of the internal structure of an agricultural greenhouse 9. Inside the agricultural greenhouse 9, an agricultural sheet 1 is stretched as an inner curtain or inner sheet so as to fit along the walls 7 and ceiling 8 or to cover above the crops 5. The agricultural sheet 1 may be deployed, stored, moved, etc., by a driving device such as a motor. The agricultural sheet 1 may be installed in various ways other than those shown in the drawings, such as only on the wall 7 side or only on the ceiling 8 side.

[0012] By providing an agricultural greenhouse 9 with an inner lining curtain made of the agricultural sheet 1, the temperature inside the agricultural greenhouse 9 during the daytime is appropriately maintained. In this embodiment, the agricultural sheet 1 is structured to balance the transmission of visible light and the blocking of infrared rays, so that the crops 5 planted in the field 6 inside the agricultural greenhouse 9 can be grown satisfactorily and a decrease in visibility inside the agricultural greenhouse 9 (as well as a decrease in workability) can be avoided while a sufficient amount of visible light is taken in, while a rise in temperature inside the agricultural greenhouse 9 is suppressed. A specific description will be given below.

[0013] <Agricultural Sheet 1> Fig. 2 is a photographed image of the agricultural sheet 1, and Fig. 2(b) is an enlarged view of Fig. 2(a). Fig. 3 is an enlarged schematic view of a partial area of ​​the agricultural sheet 1. Note that Fig. 2 shows a state in which the threads 30 on the back side of the agricultural sheet 1 can be seen through, but in Fig. 3 the threads 30 on the back side are indicated by dashed lines.

[0014] The agricultural sheet 1 has a plurality of strip-shaped yarns 50 arranged in parallel, which are woven and connected by threads 30. Any woven structure such as plain weave, leno weave, or raschel weave can be used as the woven structure. In particular, raschel weave is preferred because it maintains heat insulation, mechanical strength, breathability, and mass production properties while being less susceptible to damage even with long-term use. Generally, raschel weaves have a common structure of cross-hung yarns and loop yarns, but the weaving method differs depending on the loom. In this embodiment, any type of raschel weave may be used.

[0015] <Yarn 50 (heat-shielding yarn 10 and transparent yarn 20)> Specifically, the yarn 50 has a strip-shaped heat shielding yarn 10 and a strip-shaped transparent yarn 20, which are periodically arranged in parallel at a constant ratio. Hereinafter, when there is no need to distinguish between the heat shielding yarn 10 and the transparent yarn 20, they will be referred to as "yarn 50" for convenience.

[0016] In the agricultural sheet 1, the heat shielding yarns 10 and the transparent yarns 20 are arranged at a predetermined interval in the width direction. The light transmittance of the agricultural sheet 1 is adjusted by adjusting the ratio of the heat shielding yarns 10 to the transparent yarns 20. In this embodiment, the widths of the heat shielding yarns 10 and the transparent yarns 20 are set to the same, and the ratio between the heat shielding yarns 10 and the transparent yarns 20 is adjusted by the number of heat shielding yarns 10 and transparent yarns 20 arranged.

[0017] The ratio of the heat shielding yarns 10 to the transparent yarns 20 is set appropriately according to the performance required of the agricultural sheet 1, but from the viewpoint of the performance of the agricultural sheet 1 described below, for example, the heat shielding yarns 10 and the transparent yarns 20 are periodically arranged so that the ratio is 3:1. In a structure in which three heat shielding yarns 10 are arranged and then one transparent yarn 20 is arranged, this configuration is repeated, and adjacent yarns are woven and connected by thread 30. At this time, adjacent yarns 50 are woven so that no gaps are generated between them.

[0018] <Heat-shielding yarn 10> The heat shielding yarn 10 is obtained by stretching a thermoplastic resin film containing a heat shielding agent to a predetermined thickness and slitting it into a belt shape of a predetermined width. The heat shielding yarn 10 has a thickness of, for example, 10 to 200 μm and a width of, for example, 1 to 20 mm. In this embodiment, the heat shielding yarn 10 is in the shape of a belt having a thickness of 100 μm and a width of 4 mm.

[0019] The thermoplastic resin may be any resin capable of forming a highly transparent film. Specific examples of the thermoplastic resin include polyethylene, ethylene-vinyl acetate copolymer, polypropylene, ultra-high molecular weight polyethylene, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, vinylidene chloride resin, polyvinyl acetate, acrylic resin, ABS resin, AS resin, MBS resin, polystyrene, polyvinyl alcohol, styrene block copolymer, polyamide, polyacetal, polycarbonate, modified polyphenylene ether, polyester, fluorine resin, butyral resin, styrene-maleic acid copolymer, polyurethane resin, alkyd resin, rubber resin, cyclized rubber resin, cellulose, polybutadiene, polyimide, etc. At least one selected from these is preferable, and two or more may be used in combination. Among these, polyethylene is preferable from the viewpoint of light resistance.

[0020] As a heat shielding agent contained in the film, for example, titanium oxide-coated mica (near-infrared reflecting agent) is added. As heat shielding agents (near-infrared reflecting agents) other than titanium oxide-coated mica, (A) hydrotalcite compounds, cesium-containing tungsten oxide, tin oxide, antimony oxide, indium oxide, and composite oxides consisting of these metal oxides and other heavy metals (Cs, Rb, K, Tl, In, Ba, Li, Ca, Sr, Fe, Sn, Al, Cu, Na), and (B) organic metal complexes such as nickel dithiol complexes, phthalocyanine compounds, cyanine compounds, naphthoquinone compounds, anthraquinone compounds, diimonium compounds, and other organic dyes can be used. The amount of heat shielding agent to be added is determined in consideration of the characteristics, light transmittance, etc. of the heat shielding agent to be used.

[0021] In addition to the heat-shielding agent, various additives may be added to the thermoplastic resin composition as necessary, such as wax, metal soap, lubricant, heat stabilizer, plasticizer, processing aid, light stabilizer, UV absorber, antioxidant, mildew inhibitor, flame retardant, filler, reinforcing agent, crosslinking agent, reinforcing material, lubricant, anti-fogging agent, antistatic agent, conductive material, foaming agent, lightweight filler, colorant, etc. Any known and commonly used additives may be appropriately selected within a range that does not impair the properties of the heat-shielding yarn 10.

[0022] There are no particular limitations on the production of the film used in the heat-shielding yarn 10, but it can be produced by directly melt-kneading titanium oxide-coated mica particles into the above-mentioned thermoplastic resin, or by melt-kneading titanium oxide-coated mica particles into a thermoplastic resin at a high concentration to produce a high-concentration heat-shielding resin composition (hereinafter referred to as "master batch"), and then diluting this master batch with the above-mentioned thermoplastic resin (hereinafter, the thermoplastic resin used to dilute the master batch is referred to as "thermoplastic resin for dilution"). The master batch can be produced by mixing titanium oxide-coated mica particles together. The choice of whether to use a master batch or a heat-shielding resin composition to produce a heat-shielding film can be appropriately made by considering the advantages and disadvantages of each.

[0023] It is preferable that the thermoplastic resin used in the production of the master batch and the thermoplastic resin for dilution are the same, but different resins may be used as long as they are compatible. In the case of melt-kneading, a method in which the materials are mixed using a mixer and then melt-kneaded using a kneader is preferred. Examples of the mixer include a Henschel mixer, a tumbler, and a ribbon blender. Examples of the kneader include a single-screw extruder, a twin-screw extruder, and a kneader. The heat insulating yarn 10 can be a single layer film or a multi-layer film.

[0024] <Transparent Yarn 20> The transparent yarn 20 is obtained by stretching a thermoplastic resin film to a predetermined thickness and slitting it into a belt shape of a predetermined width. The transparent yarn 20 refers to a yarn whose opposite side is visible under visible light conditions and whose transmittance for light (visible light) of, for example, 400 to 700 nm wavelength is 50% or more, preferably 55% or more, and more preferably 60% or more. The transparent yarn 20 has a thickness of, for example, 10 to 200 μm and a width of, for example, 1 to 20 mm. In this embodiment, the transparent yarn 20 is in the shape of a belt having a thickness of 25 μm and a width of 4 mm.

[0025] The thermoplastic resin used for the transparent yarn 20 may be the same as that used for the heat shielding yarn 10. From the viewpoint of light resistance, polyethylene is preferable, and high density polyethylene (HDPE) is more preferable. The transparent yarn 20 may be a single layer film or a multilayer film.

[0026] <Ratio of heat-shielding yarn 10: transparent yarn 20> When the yarn 50 is viewed from above, the heat shielding yarn 10 and the transparent yarn 20 have a predetermined area ratio in a periodic pattern. Specifically, the heat shielding yarn 10 and the transparent yarn 20 are arranged so that the area ratio is 1:1 to 5:1. In this embodiment, the heat shielding yarn 10 and the transparent yarn 20 are each in a belt shape of the same width (4 mm) as described above. The predetermined area ratio is achieved by adjusting the number of threads when arranging the heat shielding yarn 10 and the transparent yarn 20. In this embodiment, the heat shielding yarn 10 and the transparent yarn 20 are arranged so that the area ratio (number ratio) in the width direction is 3:1 and are connected by the thread 30. The area ratio of the heat shielding yarn 10 and the transparent yarn 20 may be adjusted according to their width. For example, the area ratio can be set to 3:1 by alternately arranging the heat shielding yarn 10 with a width of 12 mm and the transparent yarn 20 with a width of 4 mm. By adjusting the ratio of the heat insulating yarn 10 to the transparent yarn 20 within the above range, the heat retaining performance and the light transmittance can be adjusted within the desired range. The heat retaining performance and the light transmittance will be described later.

[0027] <Thickness of heat-shielding yarn 10 and transparent yarn 20> The thickness of the heat-insulating yarn 10 and the transparent yarn 20 may be the same or different. Specifically, the thickness ratio of the heat shielding yarn 10 to the transparent yarn 20 can be 1:1 to 5:1. In this embodiment, the heat shielding yarn 10 has a thickness of 100 μm, the transparent yarn 20 has a thickness of 25 μm, and the thickness ratio thereof is 4:1. As described above, the heat shielding yarn 10 and the transparent yarn 20 are woven in a raschel pattern with an area ratio (number ratio) in the width direction of 3:1.

[0028] When comparing condition A, in which the heat-shielding yarn 10 and the transparent yarn 20 are all the same thickness, with condition B, in which the thickness of the heat-shielding yarn 10 is kept the same as in condition A but only the transparent yarn 20 is made thinner, it was found that within the above thickness ratio range, condition B has better heat retention performance. By setting the thicknesses of the heat-shielding yarn 10 and the transparent yarn 20 to be different, when they are connected by Russell weaving, the adhesion of the connected parts is improved, which is presumably able to suppress heat loss from there and contribute to improving heat retention (i.e., the heat retention rate described below). In this way, by making the heat-shielding yarn 10 and the transparent yarn 20 different in thickness and connecting them by raschel weaving, it is possible to improve the heat retention performance of the agricultural sheet 1 while thinning the transparent yarn 20, thereby realizing a lightweight agricultural sheet 1. As a result, it is possible to reduce the workload of installing the agricultural sheet 1 in the agricultural greenhouse 9 and to reduce the weight of the structures required for installation.

[0029] <Thread 30> The thread 30 used in the raschel weave may be, for example, a polyester resin filament, and may be a monofilament or a multifilament. The diameter of the thread 30 is preferably 10 to 400d (denier), more preferably 30 to 300d, and even more preferably 50 to 150d. By using the above material for the thread 30 and setting the diameter of the thread 30 within the above range, when the agricultural sheet 1 is manufactured by connecting the heat-shielding yarn 10 and the transparent yarn 20 by the raschel weave, flexibility, which is one of the characteristics of the raschel weave, can be obtained, and the degree of freedom in installation of the agricultural sheet 1 can be improved. In addition, a gap is unlikely to be formed between the thread 30 and the yarn 50, and the desired heat retention can be obtained. In this embodiment, for example, a polyester resin multifilament having a thread diameter of 108d is exemplified as the thread 30.

[0030] <Characteristics of agricultural sheet 1> The properties of the agricultural sheet 1, ie, heat retention performance and light transmittance, will be described below.

[0031] <<Heat retention performance>> The agricultural sheet 1 has a heat retention performance in the range of 55% to 57%. The heat retention rate P is calculated from the power measured using a measuring device 90 (manufactured by Kato Tech Co., Ltd., model number "KES-F7 Thermo Lab II type") for measuring the heat retention rate shown in Figures 4 and 5. The configuration of the measuring device 90 and the measuring method will be described below.

[0032] Fig. 4 is a diagram showing the measuring device 90. Fig. 4(a) is a front view. Fig. 4(b) is a plan view of the test chamber 94 of the measuring device 90, which is a view taken along the A1-A1 arrow in Fig. 4(b). Fig. 5 is a diagram showing the inside of the test chamber 94 of the measuring device 90 (the portion where the test piece 1a is placed).

[0033] The configuration of the measuring device 90 will be described. The measuring device 90 has a box-shaped hollow test chamber 94 and a wind tunnel 93 attached to the top of the test chamber 94 .

[0034] The test chamber 94 has a hollow box-like structure measuring 320 mm in length, 460 mm in width, and 110 mm in height, surrounded by transparent panels that allow the interior to be seen, and a wind tunnel 93 that draws air into the test chamber 94 is attached to a communication port 93a on the top surface of the test chamber 94.

[0035] The inside of the test chamber 94 contains a heater 95 of 100 mm length x 100 mm width placed on a heat insulating material provided on the bottom surface, a surface thermometer 96 (temperature sensor) for measuring the surface temperature of the heater 95, and a space 91 of 100 mm length x 100 mm width x 5 mm height provided above the heater 95 by a heat insulating spacer 97. The spacer 97 is formed into a rectangular parallelepiped from a heat insulating material, and its external shape is 200 mm length x 200 mm width x 5 mm height, and the above-mentioned space 91 is provided in the center penetrating in the thickness direction when viewed from above. The test piece 1a is cut to a size of 200 mm length x 200 mm width when viewed from above, and is placed on the upper surface of the spacer 97 so as to cover the space 91.

[0036] The wind tunnel 93 has an inner diameter of 150 mm, is provided with a fan 98 at its upper end, and is connected at its lower end to a communication port 93a of a test chamber 94, and supplies air taken in from the outside by the fan 98 to the test chamber 94. The distance between the communication port 93a and the upper surface of the spacer 97 (space 91a) is 105 mm. An anemometer (not shown) is provided near the communication port 93a, and the speed of the wind supplied to the test chamber 94 can be adjusted by adjusting the fan 98.

[0037] The heater 95 can be controlled to maintain a predetermined temperature by controlling the amount of power supplied by a voltage output method proportional to the temperature difference based on the measurement value of the surface thermometer 96.

[0038] Next, a method for measuring the heat retention rate using the measuring device 90 will be described. A wet filter paper 92 measuring 100 mm long x 100 mm wide x 0.26 mm thick is placed on the surface of the heater 95. Next, a test piece 1a is prepared by cutting the agricultural sheet 1 to 200 mm x 200 mm when viewed from above, and the test piece 1a is placed on the upper surface of the spacer 97 so as to cover the space 91.

[0039] In this state, air with a temperature of 20°C and a humidity of 65% is blown from the wind tunnel 93 toward the test piece 1a at a wind speed of 0.3 m / sec., and the power supplied to the heater 95 is controlled based on the measurement value of the surface thermometer 96 so that the surface temperature of the heater 95 is maintained at 30°C. When the amount of power per minute is W and the amount of power per minute when the test piece 1a is not placed is W0, the heat retention rate P is calculated by the following formula (1). P=(W0-W) / W0×100 (%)...Equation (1)

[0040] <<Light transmittance>> The light transmittance of the agricultural sheet 1 can be defined as follows for the wavelength ranges of (1) light with a wavelength of 400 to 700 nm (generally called visible light), (2) light with a wavelength of 700 to 1000 nm (generally called infrared light), and (3) light with a wavelength of 600 to 700 nm (orange to red). The light transmittance refers to the total average light transmittance measured by a spectrophotometer in each wavelength range. Specifically, the total light transmission spectrum is measured using an ultraviolet-visible near-infrared spectrophotometer (UH4150 ultraviolet-visible spectrophotometer manufactured by Hitachi High-Tech Science Corporation) through an integrating sphere, and the light transmittance of each wavelength range of light can be calculated.

[0041] (1) The transmittance of light having a wavelength of 400 to 700 nm (generally visible light) is 54% or more and 65% or less. The lower limit of the transmittance is preferably 56% or more, and more preferably 58% or more. The upper limit of the transmittance is preferably 64% or less, and more preferably 62% or less. By setting the visible light transmittance of the agricultural sheet 1 within the above range, it is possible to sufficiently capture the visible light necessary for the growth of the crops 5. In addition, it is possible to appropriately capture visible light, and it is possible to avoid a decrease in visibility inside the agricultural greenhouse 9, particularly in the space covered by the agricultural sheet 1, which would result in a decrease in workability. Note that if the visible light transmittance is high, it becomes difficult to adjust the near-infrared light transmittance (particularly the upper limit of the transmittance), so as described above, the upper limit of the transmittance is preferably 64% or less, and more preferably 62% or less.

[0042] (2) The transmittance of light having a wavelength of 700 to 1000 nm (generally infrared light) is 43% or more and 65% or less. The lower limit of the transmittance is preferably 44% or more, and more preferably 50% or more. The upper limit of the transmittance is preferably 62% or less, and more preferably 60% or less. Setting the infrared light transmittance of the agricultural sheet 1 within the above range suppresses temperature rise inside the agricultural greenhouse 9, particularly in the space covered by the agricultural sheet 1, and makes it easy to control the temperature to an appropriate range. In particular, setting the upper limit within the above range suppresses excessive temperature rise, thereby reducing the need for air conditioning, etc.

[0043] (3) The transmittance of light having a wavelength of 600 to 700 nm is 52% or more and 65% or less. The lower limit of the transmittance is preferably 54% or more, and more preferably 56% or more. The upper limit of the transmittance is preferably 62% or less, and more preferably 60% or less. Light in the above wavelength range is light that is actively used in photosynthesis. Therefore, by setting the transmittance of light in this range to the above range, it is possible to sufficiently capture visible light necessary for the growth of the crop 5. In general, it is considered that the wavelength bands that contribute to photosynthetic reactions are the blue wavelength band (400 to 550 nm) and the red wavelength band (600 to 700 nm). As described above, (2) the transmittance of light with a wavelength of 700 to 1000 nm is suppressed, so that the transmittance of light with an adjacent wavelength of 600 to 700 nm may also decrease. Therefore, in this embodiment, the transmittance of light with a wavelength of 600 to 700 nm is adjusted so as not to decrease too much.

[0044] <Summary of Agricultural Sheet 1> The features of the agricultural sheet 1 of this embodiment will be briefly summarized and described. (1) An agricultural sheet 1 in which a strip of heat-shielding yarn 10 containing a heat-shielding agent and a strip of transparent yarn 20 not containing a heat-shielding agent are arranged in parallel and connected by weaving with thread 30. By periodically arranging heat shielding yarns 10 and transparent yarns 20 of a specified width in parallel and weaving them with thread 30, the light transmittance and heat retention rate of the agricultural sheet 1 can be adjusted in a well-balanced manner. (2) The agricultural sheet 1 according to (1), wherein the weaving method of the yarn 30 is a raschel weave. By adopting Russell weaving as the method for weaving the heat-shielding yarn 10 and the transparent yarn 20, it is possible to realize an agricultural sheet 1 that is less likely to be damaged even with long-term use while maintaining heat-shielding properties, mechanical strength, breathability, and mass-producibility. (3) The heat retention rate P measured using a measuring device 90 of "KES-F7 Thermo Lab II Type" manufactured by Kato Tech Co., Ltd. is 55% or more and 57% or less, The measuring device 90 includes: A heater 95 measuring 100mm in length and 100mm in width placed on top of the insulation, A surface thermometer 96 (temperature sensor) for measuring the surface temperature of the heater 95; A space 91 (space A) having a length of 100 mm, a width of 100 mm, and a height of 5 mm is provided above the heater 95 by a heat insulating spacer 97. A hollow test chamber 94 having a length of 320 mm, a width of 460 mm, and a height of 110 mm, which accommodates the heater 95, the surface thermometer 96, and the space 11; a wind tunnel 93 having an inner diameter of 150 mm, which is connected to the upper part of the test chamber 94 through a communication port 93a and is capable of introducing air into the test chamber 94; a fan 98 that is provided in the wind tunnel 93 and takes in outside air and supplies the air to the space 91 at a predetermined wind speed; The heater 95 can be controlled to maintain a predetermined temperature by controlling the amount of power supplied by a temperature difference proportional voltage output method based on the measurement value of the surface thermometer 96, The distance between the space 91 and the communication port 93a of the air tunnel 93 is 105 mm, A filter paper 92 measuring 100 mm in length, 100 mm in width, and 0.26 mm in thickness is placed in a wet state on the surface of the heater 95, and a test piece 1a obtained by cutting the agricultural sheet 1 to 200 mm in length by 200 mm in width when viewed from above is placed on the upper surface of the spacer 97 so as to cover the space 11. In this state, air having a temperature of 20°C and a humidity of 65% is blown from the wind tunnel 93 to the test piece 1a at a wind speed of 0.3 m / sec. while controlling the power supplied to the heater 95 so as to maintain the surface temperature of the heater 95 at 30°C based on the measurement value of the surface thermometer 96. The amount of power per minute when the power supply to the heater 95 is controlled so as to maintain the surface temperature of the heater 95 at 30°C is W, and the amount of power per minute when the test piece 1a is not placed is W0. The agricultural sheet 1 described in (1) or (2) is calculated by the following formula (1): P=(W0-W) / W0×100 (%)...Equation (1) (4) The agricultural sheet 1 according to any one of (1) to (3), which has a transmittance of 54% or more and 65% or less for light with a wavelength of 400 to 700 nm (i.e., visible light). By setting the visible light transmittance within the above range, light in the wavelength band necessary for the growth of the crops 5 can be appropriately transmitted, and the inside of the agricultural greenhouse 9 can be prevented from becoming dark, which would reduce workability. (5) The agricultural sheet 1 according to any one of (1) to (4), which has a light transmittance of 43% or more and 65% or less at a wavelength of 700 to 1000 nm. So-called infrared light can be suppressed, and the temperature inside the agricultural greenhouse 9 can be prevented from rising excessively. (6) The agricultural sheet 1 according to any one of (1) to (5), which has a light transmittance of 52% or more and 65% or less at a wavelength of 600 to 700 nm. By setting the transmittance of so-called red light in the above range, blocking of light in the wavelength range necessary for photosynthesis of the crops 5 can be suppressed. (7) The agricultural sheet 1 according to any one of (1) to (6), wherein the heat shielding yarn 10 contains titanium oxide-coated mica as the heat shielding agent. By using titanium oxide-coated mica as the heat-shielding agent contained in the heat-shielding yarn 10, an agricultural sheet 1 that is highly safe and has stable physical properties can be realized. (8) The agricultural sheet 1 according to any one of (1) to (7), wherein the heat-shielding yarns 10 and the transparent yarns 20 are arranged in a periodic pattern. (9) The agricultural sheet 1 according to (8), wherein the ratio of the heat shielding yarns 10 to the transparent yarns 20 in the width direction is 1:1 to 5:1. (10) The agricultural sheet according to any one of (1) to (9), wherein the thickness ratio of the heat shielding yarn 10 to the transparent yarn 20 is 1:1 to 5:1. (11) A lining sheet or lining curtain used inside an agricultural greenhouse 9, the lining sheet or lining curtain being formed using the agricultural sheet 1 described in any one of (1) to (10).

[0045] Although the embodiments of the present invention have been described above, these are merely examples of the present invention, and various configurations other than those described above can also be adopted.

[0046] <Example> The present invention will be described in more detail below with reference to examples. However, the present invention is not limited to the following examples unless the gist of the present invention is changed.

[0047] <Agricultural sheets> Heat-shielding yarn and transparent yarn were prepared, arranged in parallel in a predetermined ratio, and woven using a raschel weave to prepare samples (Examples 1 to 4), a sample in which only the heat-shielding yarn was woven using a raschel weave (Comparative Example 1), and a sample in which only the transparent yarn was woven using a raschel weave (Comparative Example 2). For Examples 1 to 4 and Comparative Examples 1 and 2, the light transmittance and heat retention rate (excluding Example 4) were measured.

[0048] Heat insulating yarn: A resin composition was prepared by kneading 96 parts by weight of polyethylene resin and 4% of titanium oxide-coated mica in a twin-screw extruder, and 4 parts by weight of a light stabilizer master batch PEX UVT-54 (manufactured by Tokyo Ink Co., Ltd.) was added to 100 parts by weight of the resin composition. The mixture was then stretched to a thickness of 100 μm in an inflation molding machine to prepare a film. The film was then processed into a width of 4 mm using a slitting machine to create a heat insulating yarn. Transparent yarn: One part by weight of a light stabilizer master batch PEX UVU-36 (manufactured by Tokyo Ink Co., Ltd.) was added to 100 parts by weight of high density polyethylene resin, and the mixture was stretched to a thickness of 25 μm using a T-die film molding machine to produce a film. The film was then processed into a width of 4 mm using a slitting machine to produce a transparent yarn.

[0049] The samples of Examples 1 to 4 were prepared as follows. As a sample of Example 1, the heat insulating yarn and the transparent yarn were arranged in parallel in a ratio of 3:1 and woven in a raschel weave to obtain a sample sheet. As a sample of Example 2, the heat-shielding yarn and the transparent yarn were arranged in parallel in a ratio of 2:1 and woven in a raschel weave to obtain a sample sheet. As a sample of Example 3, the heat-shielding yarn and the transparent yarn were arranged in parallel in a ratio of 1:1 and woven in a raschel weave to obtain a sample sheet. As a sample of Example 4, the heat-shielding yarn and the transparent yarn were arranged in parallel in a ratio of 1:2 and woven in a raschel weave to obtain a sample sheet.

[0050] The samples of Comparative Examples 1 and 2 were prepared as follows. As a sample of Comparative Example 1, only the heat insulating yarns were arranged in parallel and woven in a raschel weave to obtain a sample sheet. As a sample of Comparative Example 2, only the transparent yarns were arranged in parallel and woven in a raschel weave to obtain a sample sheet.

[0051] <Measurement of light transmittance> For each of the sample sheets of Examples 1 to 4 and Comparative Examples 1 and 2, the total light transmission spectrum was measured using a measuring device (UH4150 ultraviolet-visible spectrophotometer manufactured by Hitachi High-Tech Science Corporation) through an integrating sphere, and the light transmittance for each wavelength range of light was calculated. The photometric section of the measuring device is 12 mm wide, covering three yarns (heat-shielding yarn, transparent yarn), and it was not possible to extract and measure the periodic area at once for Example 1. Therefore, the following four patterns of configurations (a) to (d) (total heat-shielding yarn:transparent yarn=3:1) were measured, and the transmittance for each wavelength was calculated from the average value. (a) Heat insulating yarn, heat insulating yarn, heat insulating yarn (b) Heat-shielding yarn, heat-shielding yarn, transparent yarn (c) Heat-shielding yarn, transparent yarn, heat-shielding yarn (d) Transparent yarn, heat insulating yarn, heat insulating yarn

[0052] The measured wavelength ranges were as follows: (1) to (4). (1) 400 to 700 nm (2) 700 to 1,000 nm (3) 400~550nm (4) 600 to 700 nm

[0053] <Heat retention rate measurement> Each of the sample sheets of Examples 1 to 4 and Comparative Examples 1 and 2 was cut to a size of 200 mm x 200 mm, and the heat retention rate was calculated using the measuring device (manufactured by Kato Tech Co., Ltd., model number "KES-F7 Thermo Lab II") and the measuring method described in Figures 4 and 5.

[0054] <Measurement results> The light transmittance results were as follows: (1) For 400 to 700 nm, it was confirmed that sufficient visible light was transmitted with a transmittance of 54% or more in Examples 1 to 4. On the other hand, it was confirmed that the visible light transmittance in Comparative Example 1 was insufficient. (2) For wavelengths from 700 to 1000 nm, in Examples 1 to 4, the transmittance was in the range of 52.3% to 62.1%, confirming that infrared light could be cut within an appropriate range. In particular, in Examples 1 to 3, the transmittance was 60% or less, confirming that when the agricultural sheet 1 was applied to an agricultural greenhouse 9, excessive temperature rise could be more effectively suppressed. In Comparative Example 1, it was confirmed that infrared light was cut too much, and in Comparative Example 2, infrared light was cut insufficiently. (3) For 400 to 550 nm, the transmittance was in the range of 56.0% to 64.0% in Examples 1 to 4. The transmittance was 52.2% in Comparative Example 1 and 66.9% in Comparative Example 2. By setting the transmittance for 400 to 550 nm within the range shown in Examples 1 to 4, particularly within the range shown in Examples 1 to 3, it becomes easy to adjust the transmittance for visible light within the above-mentioned range of 54% or more and 65% or less. (4) For 600 to 700 nm, in Examples 1 to 4, the transmittance was in the range of 57.9% to 64.4%, and it was confirmed that the light necessary for crop growth could be appropriately taken in. In Comparative Example 1, the transmittance was 53.9%, and it was confirmed that the light necessary for crop growth was excessively cut off. In particular, when the transmittance was 62% or less as in Examples 1 to 3, it became easy to adjust the balance between the amount of light that appropriately takes in the light necessary for crop growth and the near-infrared light in the adjacent wavelength range (light that contributes to temperature rise).

[0055] The heat retention rate was 55% or more and 57% or less in Examples 1 to 3. When the agricultural sheets of Examples 1 to 3 were installed in an actual agricultural greenhouse, the manager of the agricultural greenhouse (i.e., the user) commented that the temperature was easy to control even when the outside temperature was low, such as at night or in winter. The heat retention rate was 54.1% in Comparative Example 1 and 52.8% in Comparative Example 2, and opinions were obtained that it was difficult to maintain the temperature of the agricultural greenhouse 9 and that it may become lower than desired.

[0056] [Table 1] [Explanation of symbols]

[0057] 1. Agricultural Sheets 1a Test piece 5 crops 6. Field 7. Wall 8. Roof 9. Agricultural greenhouses 10 Heat-shielding yarn 20 Transparent Yarn 30 Thread 90 Measuring device (KES-F7 Thermo Lab II type) 91 Space 92 Wet filter paper 93 Wind tunnel 93a Communication port 94 Enclosure 95 Heater 96 Surface thermometer 97 Spacer 98 Fans

Claims

1. This agricultural sheet is made by connecting a strip of heat-shielding yarn containing a heat-shielding agent and a strip of transparent yarn not containing a heat-shielding agent by weaving them together with thread in a parallel arrangement.

2. 2. The agricultural sheet according to claim 1, wherein the yarn is woven in a raschel weave.

3. The heat retention rate P measured using a measuring device "KES-F7 Thermo Lab II type" manufactured by Kato Tech Co., Ltd. is 55% or more and 57% or less, The measuring device is A heater measuring 100 mm in length and 100 mm in width placed on top of insulation, A temperature sensor that measures a surface temperature of the heater; A space A having a length of 100 mm, a width of 100 mm, and a height of 5 mm is provided above the heater by a heat insulating spacer; a hollow test chamber having a length of 320 mm, a width of 460 mm, and a height of 110 mm, which accommodates the heater, the temperature sensor, and the space A; a wind tunnel having an inner diameter of 150 mm, which is connected to the upper part of the test chamber through a communication port and is capable of introducing air into the test chamber; a fan that is provided in the wind tunnel and takes in outside air to supply the air to the space at a predetermined wind speed; The heater can be controlled to maintain a predetermined temperature by controlling the amount of power supplied by a temperature difference proportional voltage output method based on the measurement value of the temperature sensor, The distance between the space A and the communication port of the wind tunnel is 105 mm, 3. The agricultural sheet according to claim 1 or 2, wherein a filter paper measuring 100 mm in length, 100 mm in width, and 0.26 mm in thickness is placed in a wet state on the surface of the heater, and a test piece obtained by cutting the agricultural sheet to 200 mm in a top view and placing it on the upper surface of the spacer so as to cover the space A. In this state, air having a temperature of 20°C and a humidity of 65% is blown from the wind tunnel to the test piece at a wind speed of 0.3 m / sec while controlling the power supplied to the heater so as to maintain the surface temperature of the heater at 30°C based on the measurement value of the temperature sensor. The amount of power per minute when W is the amount of power per minute when the test piece is not placed is W0. The heat retention rate P is calculated by the following formula (1): P=(W0-W) / W0×100 (%)...(1)

4. The agricultural sheet according to any one of claims 1 to 2, wherein the transmittance of light having a wavelength of 400 to 700 nm is 54% or more and 65% or less.

5. The agricultural sheet according to any one of claims 1 to 2, wherein the transmittance of light having a wavelength of 700 to 1000 nm is 43% or more and 65% or less.

6. 3. The agricultural sheet according to claim 1, wherein the transmittance of light having a wavelength of 600 to 700 nm is 52% or more and 65% or less.

7. 3. The agricultural sheet according to claim 1, wherein the heat insulating yarn contains titanium oxide-coated mica as the heat insulating agent.

8. 3. The agricultural sheet according to claim 1, wherein the heat-shielding yarns and the transparent yarns are arranged in a periodic pattern.

9. The agricultural sheet according to claim 8, wherein the ratio of the heat-shielding yarn to the transparent yarn in the width direction is 1:1 to 5:

1.

10. 3. The agricultural sheet according to claim 1, wherein the thickness ratio of the heat-shielding yarn to the transparent yarn is 1:1 to 5:

1.

11. 3. A lining sheet or lining curtain for use inside an agricultural greenhouse, the lining sheet or lining curtain being formed using the agricultural sheet according to claim 1 or 2.

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