Laminated film, woven / knitted fabric, and film for facility horticulture

Abstract

The purpose of the present invention is to provide a laminated film, a woven / knitted fabric, a film for facility horticulture, and the like, which do not block the growth of plants, have excellent heat insulation properties, and are excellent in handling properties such as storage and folding properties of the film. A laminated film for agricultural greenhouses that uses sunlight, the laminated film comprising a multilayer laminated film in which at least two types of resin layers having different refractive indexes are alternately laminated in the thickness direction, and having the following optical characteristics: the average transmittance at wavelengths of 430 nm to 680 nm (inclusive) is 70% or more at an incidence angle of 0 DEG, and the average transmittance at wavelengths of 430 nm to 680 nm (inclusive) is 70% or more; in addition, the average reflectance at wavelengths of 800 nm to 1100 nm is less than 80%, and the stiffness of the multilayer laminated film is less than 50.0 mN / cm.

Description

Technical Field

[0001] In the first aspect of the invention, the present invention relates to a laminated film, a woven / knitted fabric, a film for greenhouse gardening, and the like which do not block the growth of plants, have excellent heat insulation properties, and are excellent in handling properties such as film storage and folding properties.

[0002] In the second aspect of the invention, the present invention relates to a laminated film, a woven / knitted fabric, a film for greenhouse gardening, and the like which do not block the growth of plants and have excellent heat insulation properties. Background Art

[0003] So far, films with far-infrared reflection performance and visible region transmission performance have been proposed as films for agricultural greenhouses (for example, see Patent Documents 1 to 2). However, since the reflective performance is given to the film by the metal-containing layer, the visible region transmission becomes low. In addition, it has also been proposed to give the film an ultraviolet cutoff layer, but it does not have sufficient performance.

[0004] In addition, agricultural films that selectively cut off near-infrared (NIR) wavelengths with high sunlight energy have also been proposed (see, for example, Patent Document 3). However, in the above proposals, further improvements are also sought for visible light required for photosynthesis.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent No. 5464567

[0008] Patent Document 2: Japanese Patent Application Publication No. 2012-206430

[0009] Patent Document 3: Japanese Patent No. 6630187 Summary of the invention

[0010] Problem that the invention aims to solve

[0011] In addition, in addition to the above-mentioned performance, in the field of agricultural greenhouse films, the films are sometimes used in an openable and closed manner, for example, but a product which is excellent in the storage state when the films are folded or opened and closed has not been found so far.

[0012] In the first embodiment of the invention, the present invention takes the above situation into consideration and aims to provide a laminated film, a woven / knitted fabric, a film for facility gardening, etc. which does not block the growth of plants, has excellent heat insulation properties, and has excellent operability such as film storage and foldability.

[0013] In addition, in the second embodiment of the invention, the present invention has been made in view of the above circumstances, and an object of the present invention is to provide a laminated film, a woven / knitted fabric, a film for greenhouse gardening, etc. which do not block the growth of plants and have excellent heat insulation properties.

[0014] Solutions for solving problems

[0015] The present inventors have found that the above-mentioned problems can be solved by using a predetermined laminated film, and have thus completed the present invention.

[0016] <Invention method 1>

[0017] That is, the present invention provides the following laminated film. [1]

[0019] A laminated film, which is a laminated film for agricultural greenhouses utilizing sunlight,

[0020] The laminated film comprises a multilayer laminated film in which at least two resin layers having different refractive indices are alternately laminated along the thickness direction, and has the following optical properties:

[0021] When the incident angle is 0°, the average transmittance of wavelengths from 430 nm to 680 nm is 70% or more, and the average reflectance of wavelengths from 800 nm to 1100 nm is less than 80%.

[0022] The multi-layer laminated film has a rigidity of less than 50.0 mN / cm. [2]

[0024] The laminated film according to [1], wherein the laminated film has the following optical properties:

[0025] When the incident angle is 30°, the average reflectivity at a wavelength of 700 nm to 900 nm is 70% or more. [3]

[0027] The laminated film according to [1] or [2], wherein the laminated film has the following optical properties:

[0028] When the incident angle is 30°, the average transmittance at a wavelength of 450±20nm is 80% or more, the average transmittance at a wavelength of 660±20nm is 70% or more, and the average reflectance at a wavelength of 700nm to 900nm is 70% or more. [4]

[0030] The laminated film according to any one of [1] to [3], wherein the laminated film has the following optical properties:

[0031] When the incident angle is 0°, the average transmittance at a wavelength of 450±20 nm is 80% or more, the average transmittance at a wavelength of 660±20 nm is 70% or more, and the average reflectance at a wavelength of 700 nm to 900 nm is 70% or more. [5]

[0033] The laminated film according to any one of [1] to [4], wherein the optical thickness ratio of the laminated film is 0.60 or more and less than 1.0. [6]

[0035] The laminated film according to any one of [1] to [5], wherein the laminated film comprises an ultraviolet absorbing layer on at least one surface.

[0036] In addition, the present invention provides the following woven / knitted fabrics. [7]

[0038] A woven / knitted fabric comprising thin strips cut from the laminate film according to any one of [1] to [6]. [8]

[0040] A woven / knitted fabric, which is woven / knitted using thin strips cut from the laminated film described in any one of [1] to [6] as warp or weft yarns and using filament yarns or spun yarns as warp or weft yarns.

[0041] Furthermore, the present invention provides the following films for greenhouse gardening. [9]

[0043] A film for greenhouse gardening, comprising the laminated film according to any one of [1] to [6].

[0044] <Invention method 2>

[0045] That is, the present invention provides the following laminated film. [1]

[0047] A laminated film, which is a laminated film for agricultural greenhouses utilizing sunlight,

[0048] The laminated film comprises a multilayer laminated film in which at least two resin layers having different refractive indices are alternately laminated along the thickness direction, and has the following optical properties:

[0049] When the incident angle is 0°, the average transmittance at a wavelength of 430 nm to 680 nm is 80% or more, and the average reflectance at a wavelength of 800 nm to 1100 nm is less than 70%. [2]

[0051] The laminated film according to [1], wherein the laminated film has the following optical properties:

[0052] When the incident angle is 30°, the average transmittance at a wavelength of 450±20nm is 80% or more, the average transmittance at a wavelength of 660±20nm is 70% or more, and the average reflectance at a wavelength of 700nm to 900nm is 70% or more. [3]

[0054] The laminated film according to [1] or [2], wherein the laminated film has the following optical properties:

[0055] When the incident angle is 0°, the average transmittance at a wavelength of 450±20nm is 80% or more, the average transmittance at a wavelength of 660±20nm is 70% or more, and the average reflectance at a wavelength of 700nm to 900nm is 70% or more. [4]

[0057] The laminated film according to any one of [1] to [3], wherein the optical thickness ratio of the laminated film is 0.60 or more and less than 1.0. [5]

[0059] The laminated film according to any one of [1] to [4], wherein the laminated film comprises an ultraviolet absorbing layer on at least one surface.

[0060] In addition, the present invention provides the following woven / knitted fabrics. [6]

[0062] A woven / knitted fabric comprising thin strips cut from the laminate film according to any one of [1] to [5]. [7]

[0064] A woven / knitted fabric, which is woven / knitted using thin strips cut from the laminated film described in any one of [1] to [5] as warp or weft yarns and using filament yarns or spun yarns as warp or weft yarns.

[0065] Furthermore, the present invention provides the following films for greenhouse gardening. [8]

[0067] A film for greenhouse gardening, comprising the laminated film according to any one of [1] to [5].

[0068] Effects of the Invention

[0069] The laminated film of the present invention has the above-mentioned structure, so that it can be formed into a laminated film which does not block the growth of plants and has excellent heat insulation properties.

[0070] Furthermore, since the woven / knitted fabric and greenhouse horticulture film of the present invention use the laminated film, for example, in an agricultural greenhouse obtained by using the laminated film, the temperature rise in the greenhouse can be easily suppressed, thereby promoting plant growth appropriately for a long period of time.

[0071] <Invention method 1>

[0072] The laminated film of the present invention has the above-mentioned structure, so that it can be a laminated film which does not block the growth of plants, has excellent heat-insulating properties, and has excellent operability such as film storage and foldability.

[0073] In addition, since the woven / knitted fabrics and films for facility gardening of the present invention use the above-mentioned laminated films, for example, in agricultural greenhouses obtained by using them, the temperature rise in the greenhouse can be easily suppressed, and plant growth can be appropriately promoted for a long time, and the film has excellent operability such as storage and foldability.

[0074] <Invention method 2>

[0075] The laminated film of the present invention has the above-mentioned structure, so that it can be formed into a laminated film which does not block the growth of plants and has excellent heat insulation properties.

[0076] Furthermore, since the woven / knitted fabric and greenhouse horticulture film of the present invention use the laminated film, for example, in an agricultural greenhouse obtained by using the laminated film, the temperature rise in the greenhouse can be easily suppressed, thereby promoting plant growth appropriately for a long period of time. BRIEF DESCRIPTION OF THE DRAWINGS

[0077] Figure 1 Schematic diagram of an agricultural greenhouse provided with the laminated film of the present invention.

[0078] Figure 2 This is a partial front view showing an embodiment of the laminated film of the present invention.

[0079] Figure 3 It is a partial front view showing another embodiment of the laminated film of the present invention.

[0080] Figure 4 It is a schematic diagram showing the method of measuring the ring stiffness in the example of the present invention. DETAILED DESCRIPTION

[0081] Hereinafter, embodiments of the present invention will be described in detail, but the present invention is not limited to these embodiments.

[0082] In addition, in this specification, the numerical range expressed using "to" means a range including the numerical values ​​described before and after "to" as a lower limit and an upper limit.

[0083] <Laminated Film>

[0084] <Invention method 1>

[0085] The laminated film of the present invention is a laminated film for agricultural greenhouses utilizing sunlight.

[0086] The laminated film comprises a multilayer laminated film in which at least two resin layers having different refractive indices are alternately laminated along the thickness direction, and has the following optical properties:

[0087] When the incident angle is 0°, the average transmittance of wavelengths from 430 nm to 680 nm is 70% or more, and the average reflectance of wavelengths from 800 nm to 1100 nm is less than 80%.

[0088] The multi-layer laminated film has a rigidity of less than 50.0 mN / cm.

[0089] <Invention method 2>

[0090] The laminated film of the present invention is a laminated film for agricultural greenhouses utilizing sunlight.

[0091] The laminated film comprises a multilayer laminated film in which at least two resin layers having different refractive indices are alternately laminated along the thickness direction, and has the following optical properties:

[0092] When the incident angle is 0°, the average transmittance at a wavelength of 430 nm to 680 nm is 80% or more, and the average reflectance at a wavelength of 800 nm to 1100 nm is less than 70%.

[0093] It should be noted that, in the present invention, visible light refers to light having a wavelength of 400 nm to 800 nm, and heat rays refer to light having a wavelength of 800 nm to 1400 nm.

[0094] 〔Multi-layer laminated film〕

[0095] The laminated film includes a multilayer laminated film in which at least two types of resin layers having different refractive indices are alternately laminated in the thickness direction.

[0096] As the above-mentioned multilayer laminated film, for example, the outermost layer is a layer (hereinafter also referred to as a "multilayer laminated structure") in which more than 20 layers of a first resin layer (hereinafter also referred to as a "first layer") and a second resin layer (hereinafter also referred to as a "second layer") having different refractive indices are alternately laminated along the thickness direction.

[0097] The multilayer laminated film in the present invention preferably has a laminated structure portion obtained by alternately laminating the aforementioned first layer and the second layer totaling more than 51 layers. The upper limit of the number of layers can be, for example, 1001 layers or the like, and from the viewpoint of productivity, preferably up to 900 layers. In addition, the lower limit of the number of layers is more preferably more than 100 layers, and more preferably more than 150 layers. When the number of layers is less than the lower limit, sometimes the selective reflection based on multiple interference is small, and sufficient near-infrared reflection performance cannot be obtained.

[0098] As the resin of the resin layer forming the above-mentioned multi-layer laminated structure, it is possible to adopt the resin known to itself, such as polyester, polysulfone, polyamide, polyether, polyketone, polyacrylic acid, polycarbonate, polyacetal, polystyrene, polyamide-imide, polyarylate, polyolefin, polyfluoropolymer, polyurethane, polyaryl sulfone, polyether sulfone, polyarylether sulfide, polyvinyl chloride, polyetherimide, tetrafluoroethylene, polyether ketone etc. can be listed, they are not limited to homopolymer, also can be copolymerized. They can be used alone, or, also can be used in combination with more than two kinds. In addition, from the aspect of easily improving the difference of the refractive index between resins, preferably at least one in the resin layer is a resin with condensed aromatic rings such as naphthalene rings that are easy to improve the refractive index as a repeating unit, and can also exist in the form of copolymerization components.

[0099] Among these, the resin used in the resin layer with a high refractive index (for example, as the first layer) is preferably a crystalline thermoplastic resin from the viewpoint of being easy to show a high degree of molecular orientation by stretching, and a thermoplastic resin having a melting point of 200° C. or higher is particularly preferred. From this viewpoint, as a specific thermoplastic resin, polyester is preferred, and polyethylene naphthalate and polyethylene terephthalate are more preferred.

[0100] The following describes an example in which polyethylene naphthalate is used as the resin used in the first layer.

[0101] As the polyethylene naphthalate, any known substance can be used as appropriate. As the polyethylene naphthalate, for example, polyethylene 2,6-naphthalate is preferred, and in particular, polyethylene 2,6-naphthalate having a condensed aromatic ring is preferred from the viewpoint of having a high refractive index and being able to be stretched at a high stretching ratio.

[0102] The proportion of the monomer component in the polyethylene naphthalate, i.e., the ethylene naphthalate component, is preferably 95 mol% or more and 100 mol% or less, more preferably 96 mol% or more, and further preferably 97 mol% or more, based on the total repeating units constituting the polyethylene naphthalate. If the proportion of the ethylene naphthalate component as the main component does not satisfy the lower limit, the melting point and / or glass transition temperature of the polyethylene naphthalate constituting the first layer decreases, making it difficult to obtain a temperature difference in melting point and / or glass transition temperature with the polyethylene terephthalate constituting the second layer described later, and as a result, it may be difficult to provide a sufficient refractive index difference to the biaxially stretched laminated polyester film.

[0103] As copolymer components other than the main component constituting the above-mentioned polyethylene naphthalate, there can be listed, for example, aromatic carboxylic acids such as isophthalic acid, terephthalic acid, phthalic acid, naphthalene dicarboxylic acid other than the main naphthalene dicarboxylic acid, and biphenyl dicarboxylic acid; aliphatic dicarboxylic acids such as succinic acid, adipic acid, azelaic acid, sebacic acid, and decanedicarboxylic acid; acid components such as alicyclic dicarboxylic acids such as cyclohexane dicarboxylic acid; aliphatic diols such as diethylene glycol, propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, and neopentyl glycol; alicyclic diols such as 1,4-cyclohexanedimethanol; and diol components such as polyethylene glycol and polytetramethylene glycol.

[0104] Among the above copolymer components, at least one selected from the group consisting of isophthalic acid, terephthalic acid, neopentyl glycol, 1,4-cyclohexanedimethanol and diethylene glycol is preferred. Among these copolymer components, isophthalic acid and terephthalic acid are particularly preferred. These copolymer components may be used alone or in combination of two or more.

[0105] The above-mentioned polyethylene naphthalate can be manufactured by appropriately applying a known method. For example, it can be manufactured by subjecting the diol component, the dicarboxylic acid component and the copolymer component as required to an esterification reaction, and then subjecting the obtained reaction product to a polycondensation reaction to make a polyester. In addition, it can also be manufactured by subjecting the derivatives of these raw monomers to an ester exchange reaction, and then subjecting the obtained reaction product to a polycondensation reaction to make a polyester. Furthermore, it can also be a method of obtaining by using two or more polyesters to be melt-kneaded in an extruder to cause an ester exchange reaction (redistribution reaction) to obtain.

[0106] The intrinsic viscosity of the polyethylene naphthalate constituting the first layer is preferably 0.40 dl / g or more and 0.80 dl / g or less, and can be, for example, 0.45 dl / g or more and 0.75 dl / g or less. When the intrinsic viscosity of the polyethylene naphthalate constituting the first layer is not within this range, the difference between the intrinsic viscosity of the polyethylene terephthalate constituting the second layer may become large, and as a result, when an alternating layer structure is formed, the layer structure may be disordered, or although film formation is possible, the film forming property may be reduced. When two or more polyesters are obtained by melt mixing in an extruder and causing an ester exchange reaction, the intrinsic viscosity of each polyester may be within the above range.

[0107] In addition, the glass transition temperature of the polyethylene naphthalate constituting the first layer is preferably higher than the glass transition temperature of the polyethylene terephthalate constituting the second layer.

[0108] On the other hand, as the resin used in the resin layer with low refractive index (for example, as the above-mentioned second layer), there is no particular limitation as long as it can show sufficient refractive index difference with the resin layer with high refractive index and can maintain necessary adhesion. For example, it is also possible to use a resin in which a copolymer component capable of reducing the refractive index is copolymerized in the resin used in the resin layer with high refractive index. In addition, from the aspect of not needing to increase the refractive index by stretching, etc., it is also possible to use a non-crystalline resin or a resin having a sufficiently low melting point compared with the resin of the resin layer with high refractive index. For example, it is possible to suitably use a non-crystalline polyester containing ethylene terephthalate components. In addition, polylactic acid, acrylic resin, polycarbonate, polystyrene can also be used as the resin used in the resin layer with low refractive index.

[0109] The following describes an example in which polyethylene terephthalate is used as the resin used for the second layer.

[0110] When the polyethylene terephthalate is used, the initial transparency and reflectivity of the film can be improved by selecting the processing conditions during film formation, but sometimes crystallization occurs due to heating during post-processing, which is accompanied by a decrease in transparency and reflectivity characteristics. By using amorphous polyester as the polyethylene terephthalate of the second layer, the initial high transparency and reflectivity of the film can be maintained even after heating during post-processing.

[0111] For example, polyesters containing 50 mol% or more and 80 mol% or less of ethylene terephthalate components as the ethylene terephthalate based on all repeating units of the polyethylene terephthalate constituting the second layer can be cited, and more preferably, copolymerized polyethylene terephthalate containing 55 mol% or more and 75 mol% or less of ethylene terephthalate components (i.e., preferably 20 mol% or more and 50 mol% or less, more preferably 25 mol% or more and 45 mol% or less of copolymer components) can be cited. The copolymerization amount can be adjusted within the above-mentioned range according to the type of copolymerization component used, and for example, when the copolymerization component of the copolymerized PET is isophthalic acid or naphthalene dicarboxylic acid, the amount is about 30 mol% or more.

[0112] When the copolymerization amount is less than the lower limit, crystallization and orientation are likely to occur during film making, and it is difficult to produce a refractive index difference with the first layer, and the near-infrared reflection ability is easily reduced. In addition, the haze increases due to crystallization during film making. On the other hand, when the copolymerization amount exceeds the upper limit, the heat resistance and film-forming properties during film making (especially during extrusion) are easily reduced. In addition, when the copolymerization component is a component that imparts high refractive index, the refractive index difference with the first layer is easily reduced due to the increase in refractive index. By making the copolymerization amount within the above range, it is possible to maintain good heat resistance and film-forming properties, and fully ensure the refractive index difference with the first layer, and it is possible to impart sufficient near-infrared reflection performance.

[0113] As copolymer components preferably used in the above-mentioned polyethylene terephthalate constituting the second layer, there can be listed, for example, aromatic dicarboxylic acids such as isophthalic acid, 2,6-naphthalene dicarboxylic acid, and 2,7-naphthalene dicarboxylic acid, aliphatic dicarboxylic acids such as adipic acid, azelaic acid, sebacic acid, and decanedicarboxylic acid, and alicyclic dicarboxylic acids such as cyclohexane dicarboxylic acid; and diol components such as aliphatic diols such as butanediol and hexanediol, alicyclic diols such as cyclohexanedimethanol, and spirodiol. Among them, isophthalic acid, 2,6-naphthalene dicarboxylic acid, cyclohexanedimethanol, and spirodiol are preferred, and when copolymer components other than these are included, the copolymerization amount is preferably 10 mol% or less. In particular, from the viewpoint of low refractive index and small decrease in molecular weight during extrusion, the copolymer component of the above-mentioned polyethylene terephthalate is preferably 1,4-cyclohexanedimethanol.

[0114] The intrinsic viscosity of the polyethylene terephthalate is preferably 0.4 dl / g to 1.0 dl / g, for example, 0.45 dl / g to 0.95 dl / g or 0.5 dl / g to 0.95 dl / g. If the intrinsic viscosity of the polyethylene terephthalate constituting the second layer is not within this range, the difference in intrinsic viscosity from the polyethylene naphthalate constituting the first layer may become large, resulting in a disordered layer structure when an alternately stacked structure is formed, or film formation may be possible but the film forming property may be reduced.

[0115] When two or more polyesters are used and melt-mixed in an extruder to undergo an ester exchange reaction, the intrinsic viscosity of each polyester may be within the above range.

[0116] The above-mentioned polyethylene terephthalate can be manufactured by appropriately applying known methods. For example, it can be manufactured by causing an acid component, a diol component and a copolymer component as a main component to undergo an esterification reaction, and then causing the obtained reaction product to undergo a polycondensation reaction to make a polyester. In addition, it can also be manufactured by causing a derivative of these raw monomers to undergo an ester exchange reaction, and then causing the obtained reaction product to undergo a polycondensation reaction to make a polyester. Furthermore, it can also be a method of obtaining by using two or more polyesters to undergo an ester exchange reaction (redistribution reaction) in an extruder by melt-kneading them.

[0117] The first layer and the second layer may contain a small amount of additives within a range not impairing the purpose of the present invention, and examples thereof include lubricants such as inactive particles, colorants such as pigments and dyes, stabilizers, flame retardants, and foaming agents.

[0118] Furthermore, it is preferred that the thickness of each of the first layer and the second layer be a thickness capable of obtaining an effect of selectively reflecting near-infrared light by optical interference between the layers.

[0119] Here, the reflection wavelength of the multilayer laminated film corresponds to twice the sum of the optical thicknesses of the adjacent first and second layers. The optical thickness is represented by the product of the refractive index and the thickness of each layer, and the thickness of each layer is preferably adjusted according to the refractive index of the resin used and the target reflection wavelength.

[0120] In the present invention, the optical thickness and the ratio thereof are calculated according to the following formula.

[0121] Optical thickness ratio = (n1×d1) / (n2×d2)

[0122] n1 Refractive index of the first layer

[0123] n2 The refractive index of the second layer

[0124] d1 thickness of the first layer

[0125] d2 thickness of the second layer

[0126] In addition, as shown in "Reflectivity of Iridescent Co-extruded Multilayered Plastic Films" by Radford et al., Polymer Engineering and Science, Vol. 13, No. 3, May 1973, for multilayer films that utilize multilayer interference based on quarter-wavelength, even if no main reflection peak is generated in the visible light region, if high-order reflection peaks are generated in the visible light region, it sometimes affects the reduction of photosynthesis. Therefore, it is preferably set to an appropriate optical thickness for removing high-order reflections.

[0127] When the optical thickness ratio of the multilayer interference film (the ratio of the optical thickness of the second layer of the main reflection peak to the optical thickness of the first layer) is 1.0, the second order (1 / 2 wavelength of the main reflection peak) and the fourth order (1 / 4 wavelength of the main reflection peak) in the high-order peak can be removed. Therefore, the laminated film capable of shielding infrared rays of the present invention is preferably adjusted in such a way that the thickness of the adjacent second layer is close to 1.0 relative to the thickness of the first layer after considering the refractive index of the layers of the multilayer laminated film, because it can prevent the secondary reflection peak from appearing in the visible light region and causing the influence on the reduction of photosynthesis.

[0128] Thus, the optical thickness ratio of the multilayer laminated film is preferably 0.60 or more and less than 1.0. Regarding the optical thickness ratio of the multilayer laminated film, according to the purpose of use and the purpose, the lower limit value can be, for example, 0.65 or more, 0.70 or more, 0.75 or more, 0.77 or more, 0.79 or more, or 0.8 or more, and the upper limit value can be 0.99 or less, 0.98 or less, 0.97 or less, 0.95 or less, 0.93 or less, 0.91 or less, or 0.90 or less. Changing the optical thickness ratio from 1.0 is not a commonly performed operation, especially in the case of a multilayer laminated film, it will not be studied first, but in the present invention, by setting it to the above-mentioned structure, it is possible to effectively prevent the secondary reflection peak in the interfering multilayer laminated film from appearing in the visible light region, resulting in the influence on the reduction of photosynthesis.

[0129] As an example of the appropriate optical thickness for removing high-order reflection, the thickness of each layer is described when polyethylene 2,6-naphthalate (hereinafter referred to as "PEN") is used as the first layer and copolymerized polyethylene terephthalate copolymerized with 30 mol% cyclohexanedimethanol (hereinafter referred to as "CHDM30PET") is used as the second layer, and the wavelength of 700 nm to 900 nm is reflected once. It also depends on the film forming conditions of the film. Generally speaking, the refractive index of PEN in the stretching direction is 1.74 to 1.78, and the refractive index of CHDM30PET is about 1.55 to 1.58. Therefore, the thickness of each layer of the first layer is preferably in the range of 0.09 μm to 0.18 μm, and the thickness of each layer of the second layer is preferably in the range of 0.09 μm to 0.23 μm, and particularly preferably in the range of 0.10 μm to 0.20 μm. By making each layer of the first layer and the second layer have a thickness in this range, it is possible to selectively reflect and block light in the near-infrared region.

[0130] 〔Protective functional layer〕

[0131] The laminated film may include a protective layer on at least one outermost layer of the multi-layer laminated structure.

[0132] The protective layer preferably contains the resin used in the first layer.

[0133] The protective layer is preferably a layer mainly composed of polyethylene naphthalate. Regarding polyethylene naphthalate and the like, the same as described in the first layer can be appropriately used.

[0134] It should be noted that, in the present invention, “mainly composed of polyethylene naphthalate” means that the total amount of the protective layer contains 50% by mass or more of polyethylene naphthalate, for example, 80% by mass or more, or 90% by mass or more.

[0135] The thickness of the protective layer is 10 μm or less, for example, 1 μm to 9 μm, 2 μm to 8 μm, 3 μm to 7 μm, or 4 μm to 5 μm.

[0136] In addition, when a plurality of protective layers are provided in the laminated film, such as when the two outermost layers of the multilayer laminated structure have protective layers, the thickness of the protective layer means the thickness of each of them.

[0137] 〔Surface functional layer〕

[0138] The surface functional layer of the present invention is, for example, a layer provided on at least one surface of the above-mentioned laminated film, and is formed of a resin composition containing particles and a resin.

[0139] The particles may be inorganic particles, organic particles, or organic-inorganic composite particles. Specifically, particles such as silicon dioxide, acrylic resins, styrene resins, acrylic / styrene copolymer resins, organosilicon, melamine resins, benzoguanamine resins, etc. may be used. They may be used alone, or two or more may be mixed.

[0140] The particles are preferably organic particles, specifically the organic particles exemplified above, more preferably acrylic resins, styrene resins, and acrylic / styrene copolymer resins, and particularly preferably acrylic resin particles from the viewpoint of heat resistance and solvent resistance.

[0141] The average particle size of the above-mentioned particles is greater than or equal to 4 μm and less than or equal to 10 μm, for example, greater than or equal to 4.5 μm and less than or equal to 9.5 μm, greater than or equal to 5 μm and less than or equal to 9 μm, greater than or equal to 5.5 μm and less than or equal to 8.5 μm, greater than or equal to 6 μm and less than or equal to 8 μm, greater than or equal to 6.5 μm and less than or equal to 7.5 μm, or greater than or equal to 6.7 μm and less than or equal to 7 μm.

[0142] In the present invention, the average particle size of the particles is measured by the following method.

[0143] First, a cross section of the surface functional layer is cut parallel to the longitudinal direction using a microtome method, and a metal used to impart conductivity to the particle surface is extremely thinly sputtered on the cross section. The image is magnified 10,000 to 30,000 times using a transmission electron microscope (TEM), and the area circle equivalent diameter is calculated based on the image obtained using the following formula.

[0144] Formula: Average particle size = sum of area circle equivalent diameters of measured particles / number of measured particles (at least 100 or more)

[0145] The particle content in the surface functional layer is 0.3 mass parts or more and 1.5 mass parts or less relative to 100 mass parts of resin contained in the surface functional layer, for example, it can be 0.4 mass parts or more and 1.4 mass parts or less, 0.5 mass parts or more and 1.3 mass parts or less, 0.6 mass parts or more and 1.2 mass parts or less, 0.7 mass parts or more and 1.1 mass parts or less, 0.8 mass parts or more and 1 mass parts or less, or 0.85 mass parts or more and 9 mass parts or less.

[0146] In addition, as the above-mentioned particles, spherical particles are preferably used. The higher the sphericity of the spherical particles, the more preferred, and the aspect ratio is preferably 1.3 or less, particularly preferably 1.1 or less. It should be noted that the particles are preferably colorless and transparent particles. Here, colorless and transparent means: there is substantially no coloring that reduces the color purity of the three primary colors, and the light transmittance is excellent.

[0147] In addition, the thickness of the above-mentioned surface functional layer is more than 0.5 relative to the ratio of the average particle diameter of the particles included in the surface functional layer. By setting the thickness ratio to more than 0.5, it is possible to suppress the falling off of particles from the surface functional layer. In addition, the upper limit of the above-mentioned thickness ratio is not particularly limited, and from the viewpoint of suppressing material cost, is preferably less than 3, more preferably less than 2.5, and further preferably less than 2.

[0148] When the average particle size of particles contained in the surface functional layer is larger than the thickness of the surface functional layer (ie, the above ratio is less than 1), the thickness of the surface functional layer refers to the thickness measured at a location where no particles exist.

[0149] The resin composition comprises a resin as a binder component. Specific examples of the resin include acrylic resins, polyester resins, polyolefin resins, urethane resins, fluororesins, etc. These can be used alone or in combination of two or more.

[0150] The resin is the main component of the resin composition (ie, contains 50% by mass or more), and is preferably contained in an amount of 70% by mass or more, and may be contained in an amount of 90% by mass or more, or 95% by mass or more, based on the entire resin composition.

[0151] The resin may contain a known ultraviolet absorber as appropriate, and preferably contains an ultraviolet absorber having a triazine skeleton.

[0152] In addition, in the present invention, when the surface functional layer contains the ultraviolet absorber, it may be referred to as an ultraviolet absorbing layer.

[0153] As the ultraviolet absorber having a triazine skeleton, any known ultraviolet absorber can be appropriately used as long as it has a triazine skeleton in the molecule.

[0154] Examples of the ultraviolet absorber having a triazine skeleton include 2-(2-hydroxy-4-hexyloxyphenyl)-4,6-diphenyl-s-triazine, 2-(2-hydroxy-4-propoxy-5-methylphenyl)-4,6-bis(2,4-dimethylphenyl)-s-triazine, 2-(2-hydroxy-4-hexyloxyphenyl)-4,6-biphenyl-s-triazine, 2,4-diphenyl-6-(2-hydroxy-4-methoxyphenyl)-s-triazine, 2,4-diphenyl-6-(2-hydroxy-4-ethoxyphenyl)-s-triazine, 2,4-diphenyl-6-(2-hydroxy-4-propoxyphenyl)-5-methylphenyl)-4,6-bis(2,4-dimethylphenyl)-s-triazine, phenyl)-s-triazine, 2,4-diphenyl-6-(2-hydroxy-4-butoxyphenyl)-s-triazine, 2,4-bis(2-hydroxy-4-octyloxyphenyl)-6-(2,4-dimethylphenyl)-s-triazine, 2,4,6-tris(2-hydroxy-4-hexyloxy-3-methylphenyl)-s-triazine, 2,4,6-tris(2-hydroxy-4-octyloxyphenyl)-s-triazine, 2-(4-isooctyloxycarbonylethoxyphenyl)-4,6-diphenyl-s-triazine, 2-(4,6-diphenyl-s-triazine-2-yl)-5-(2-(2-ethylhexanoyloxy)ethoxy)phenol, etc. These may be used alone or in combination of two or more.

[0155] The content of the above-mentioned ultraviolet absorber in the above-mentioned weather-resistant resin layer is preferably 8 parts by mass or more and 45 parts by mass or less relative to 100 parts by mass of the resin contained in the surface functional layer, for example, it can be 10 parts by mass or more and 40 parts by mass or less, 12 parts by mass or more and 35 parts by mass or less, 13 parts by mass or more and 30 parts by mass or less, 14 parts by mass or more and 25 parts by mass or less, or 15 parts by mass or more and 20 parts by mass or less.

[0156] The thickness of the surface functional layer is adjusted according to the application, for example, in the range of 1 μm to 125 μm, for example, 2 μm to 100 μm, 3 μm to 90 μm, 5 μm to 80 μm, or 10 μm to 60 μm.

[0157] The surface functional layer may contain a small amount of additives within a range that does not impair the purpose of the present invention, and examples thereof include lubricants such as inactive particles other than the above particles, leveling agents for improving film quality, colorants such as pigments and dyes, stabilizers, flame retardants, foaming agents and the like.

[0158] [Heat ray reflecting layer]

[0159] The multilayer laminated film itself has a heat ray reflecting function, but a known heat ray reflecting layer may be further provided as needed.

[0160] [Laminated film]

[0161] <Invention method 1>

[0162] The laminated film of the present invention comprises the above-mentioned multi-layer laminated film and has the following optical properties:

[0163] When the incident angle is 0°, the average transmittance of wavelengths from 430 nm to 680 nm is 70% or more, and the average reflectance of wavelengths from 800 nm to 1100 nm is less than 80%.

[0164] The multi-layer laminated film has a rigidity of less than 50.0 mN / cm.

[0165] In the present invention, the spectral transmittance refers to the value measured by a spectrophotometer, and the spectral transmittance of wavelengths of 300 nm or more and 1800 nm or less is measured at intervals of 2 nm, and the spectral transmittance of each wavelength is measured. In addition, the average transmittance in each wavelength range is calculated. It should be noted that the measurement is performed in an atmospheric atmosphere at 25°C, and the incident angle of the measurement light is set to 0° or 30°.

[0166] The laminated film of the present invention is designed in such a way that it has the optical characteristics of having an average transmittance of 70% or more at wavelengths above 430nm and 680nm and an average reflectivity of less than 80% at wavelengths above 800nm ​​and below 1100nm when the incident angle is 0°, from the viewpoint of having both a heat ray reflection function and a high total light transmittance in a wavelength range that is beneficial to plant growth.

[0167] The average transmittance at a wavelength of 430 nm or more and 680 nm or less when the incident angle is 0° may be, for example, 71% or more, 72% or more, 73% or more, 74% or more, 75% or more, 76% or more, 77% or more, 78% or more, 79% or more, 80% or more, 81% or more, 82% or more, 83% or more, 84% or more, 85% or more, 86% or more, or 87% or more, depending on the purpose and application.

[0168] The average reflectivity at a wavelength of 800 nm or more and 1100 nm or less when the incident angle is 0° may be, for example, 79% or less, 78% or less, 77% or less, 76% or less, 75% or less, 74% or less, 73% or less, 72% or less, 71% or less, 70% or less, 69% or less, 68% or less, 67% or less, 66% or less, 65% or less, 60% or less, 55% or less, or 50% or less, depending on the purpose of use and application. The altitude of the sun varies with latitude and time. In particular, when considering the effect of the heat insulation material in the hot summer season from the spring equinox to the autumn equinox in the hot summer area south of Tokyo, Japan, it is more effective to design the light transmission and heat insulation effect that contribute to photosynthesis by considering that the incident angle of sunlight relative to the film surface is 30°. Therefore, by setting the above-mentioned structure, it is possible to effectively prevent the influence on the reduction of photosynthesis caused by the appearance of the secondary reflection peak in the interfering multi-layer laminated film in the visible light region.

[0169] In addition, the above-mentioned laminated film preferably has the following optical properties, for example:

[0170] When the incident angle is 30°, the average reflectivity at a wavelength of 700 nm to 900 nm is 70% or more.

[0171] The average transmittance at a wavelength of 700 nm or more and 900 nm or less when the incident angle is 30° can be, depending on the purpose and application, for example, 71% or more, 72% or more, 73% or more, 74% or more, 75% or more, 76% or more, 77% or more, 78% or more, 79% or more, 80% or more, 81% or more, 82% or more, 83% or more, 84% or more, 85% or more, 86% or more, or 87% or more.

[0172] In addition, the laminated film preferably has the following optical properties:

[0173] When the incident angle is 30°, the average transmittance at a wavelength of 450±20nm is 80% or more, the average transmittance at a wavelength of 660±20nm is 70% or more, and the average reflectance at a wavelength of 700nm to 900nm is 70% or more.

[0174] The average transmittance at a wavelength of 450±20nm when the incident angle is 30° may be, for example, 81% or more, 82% or more, 83% or more, 84% or more, 85% or more, 86% or more, 87% or more, 88% or more, or 89% or more, depending on the purpose of use and application. By setting the above configuration, it is effective to obtain the light transmission required for photosynthesis of plants.

[0175] The average transmittance at a wavelength of 660±20nm when the incident angle is 30° may be, for example, 71% or more, 72% or more, 73% or more, 74% or more, 75% or more, 76% or more, 77% or more, 78% or more, 79% or more, 80% or more, or 81% or more, depending on the purpose of use and application. By setting the above configuration, it is effective to obtain the light transmission required for photosynthesis of plants.

[0176] The average reflectivity at a wavelength of 700 nm or more and 900 nm or less at an incident angle of 30° may be, for example, 81% or more, 82% or more, 83% or more, 84% or more, 85% or more, 86% or more, 87% or more, 88% or more, 89% or more, 90% or more, 91% or more, 92% or more, 93% or more, 94% or more, 95% or more, 96% or more, 97% or more, or 98% or more, depending on the purpose of use and the application. By setting the above configuration, it is effective to obtain the light transmission required for photosynthesis of plants.

[0177] In addition, the laminated film preferably has the following optical properties:

[0178] When the incident angle is 0°, the average transmittance at a wavelength of 450±20 nm is 80% or more, the average transmittance at a wavelength of 660±20 nm is 70% or more, and the average reflectance at a wavelength of 700 nm to 900 nm is 70% or more.

[0179] The average transmittance at a wavelength of 450±20nm when the incident angle is 0° may be, for example, 81% or more, 82% or more, 83% or more, 84% or more, 85% or more, 86% or more, 87% or more, 88% or more, or 89% or more, depending on the purpose of use and application. By setting the above configuration, it is effective to obtain the light transmission required for photosynthesis of plants.

[0180] The average transmittance at a wavelength of 660±20nm when the incident angle is 0° may be, for example, 71% or more, 72% or more, 73% or more, 74% or more, 75% or more, 76% or more, 77% or more, 78% or more, 79% or more, 80% or more, 81% or more, 82% or more, 83% or more, 84% or more, 85% or more, or 86% or more, depending on the purpose of use and application. By setting the above configuration, it is effective to obtain the light transmission required for photosynthesis of plants.

[0181] The average reflectivity at a wavelength of 700 nm or more and 900 nm or less when the incident angle is 0 ° can be, for example, 71% or more, 72% or more, 73% or more, 74% or more, 75% or more, 76% or more, 77% or more, 78% or more, 79% or more, 80% or more, 81% or more, 82% or more, 83% or more, 84% or more, 85% or more, 86% or more, 87% or more, 88% or more, 89% or more, 90% or more, 91% or more, or 92% or more, depending on the purpose of use and the purpose of application. By setting the above-mentioned structure, the effect of heat insulation from sunlight can be obtained, which is effective. In addition, the influence on the reduction of photosynthesis caused by the appearance of the secondary reflection peak in the visible light region can be effectively prevented.

[0182] In addition, the ratio of the optical thickness of the above-mentioned laminated film is preferably more than 0.60 and less than 1.0. The ratio of the optical thickness of the above-mentioned laminated film is based on the purpose of use and the purpose, and the lower limit value can be, for example, more than 0.65, more than 0.67, more than 0.70, more than 0.75 or more than 0.8, and the upper limit value can be less than 0.99, less than 0.98, less than 0.97, less than 0.95, less than 0.93, less than 0.91 or less than 0.90. By being set to the above-mentioned structure, it is possible to effectively prevent the secondary reflection peak in the interfering multi-layer laminated film from appearing in the visible light region and causing the influence on the reduction of photosynthesis. In addition, the optical thickness is determined according to the situation of the above-mentioned multi-layer laminated film. In addition, the greater the value of the optical thickness, the higher the rigidity of the film, and the smaller the value of the optical thickness, the more the rigidity of the film can be reduced, and the value of the ring rigidity also decreases, especially in the case of being used for agricultural greenhouse purposes, it is possible to improve operability and easy storage when opening and closing.

[0183] In addition, the laminated film has a rigidity of less than 50.0 mN / cm.

[0184] The rigidity in the present invention can be measured by ring rigidity measurement as shown in the examples. The ring rigidity is the repulsive force of a ring measured when a ring is formed by pressing a predetermined amount in the radial direction using a film cut into strips of a predetermined size, which is an index indicating the rigidity of the film.

[0185] use Figure 4 To explain in more detail, a film cut into strips of a specified size is used as a test piece, and the test piece is clamped and fixed on a chuck in such a way that the test piece forms a ring. The ring portion of the test piece is compressed by a pressing head at a specified speed, and the rebound force relative to the pressing head is measured and set as the ring stiffness.

[0186] The larger the value of the ring stiffness is, the higher the rigidity of the film is, and the smaller the value is, the lower the rigidity of the film is. For example, when used for agricultural greenhouses, operability and storage during opening and closing are easily achieved.

[0187] When the laminated film of the present invention is used as a film for greenhouse horticulture, for example, it can fully supply plants with visible light that is a driving source for photosynthesis. Furthermore, it is believed that the laminated film of the present invention has a high total light transmittance and can therefore fully promote plant growth.

[0188] In addition, by having the above-mentioned structure, when the laminated film of the present invention is applied to a film for greenhouse gardening, for example, it is possible to fully block heat rays that raise the temperature in an agricultural greenhouse. Furthermore, since the heat release of the film itself, such as a heat ray absorbing film, is small, it is possible to suppress the temperature rise in the agricultural greenhouse and reduce the cost required for dehumidification and cooling equipment. In addition, the operability of the film, such as storage and foldability, is excellent, and therefore, it is particularly suitable as a film for greenhouse gardening used in applications such as those having an opening and closing portion, a folding portion, etc.

[0189] <Invention method 2>

[0190] The laminated film of the present invention comprises the above-mentioned multi-layer laminated film and has the following optical properties:

[0191] When the incident angle is 0°, the average transmittance at a wavelength of 430 nm to 680 nm is 80% or more, and the average reflectance at a wavelength of 800 nm to 1100 nm is less than 70%.

[0192] In the present invention, the spectral transmittance refers to the value measured by a spectrophotometer, and the spectral transmittance of the wavelength of 300 to 1800 nm is measured at intervals of 2 nm, and the spectral transmittance of each wavelength is measured. In addition, the average transmittance in each wavelength range is calculated. It should be noted that the measurement is carried out in an atmospheric atmosphere at 25°C, and the incident angle of the measurement light is set to 0° or 30°.

[0193] The laminated film of the present invention is designed in such a way that it has the optical characteristics of having an average transmittance of 80% or more at wavelengths above 430nm and 680nm when the incident angle is 0°, and an average reflectance of less than 70% at wavelengths of 800 to 1100nm, from the viewpoint of having both a heat ray reflection function and a high total light transmittance in a wavelength range that is beneficial to plant growth.

[0194] The average transmittance at a wavelength of 430 nm to 680 nm when the incident angle is 0° may be, for example, 81% or more, 82% or more, 83% or more, 84% or more, 85% or more, 86% or more, or 87% or more depending on the purpose and application.

[0195] The average reflectivity at a wavelength of 800 nm or more and 1100 nm or less when the incident angle is 0° may be, for example, 69% or less, 68% or less, 67% or less, 66% or less, 65% or less, 60% or less, 55% or less, or 50% or less, depending on the purpose and application. The altitude of the sun varies with latitude and time. Especially when considering the effect of the thermal insulation material in the hot summer season from the spring equinox to the autumnal equinox in the hot summer area south of Tokyo, Japan, it is more effective to design the light transmission and thermal insulation effect that contribute to photosynthesis by considering that the incident angle of sunlight relative to the film surface is 30°. Therefore, by setting the above-mentioned structure, it is possible to effectively prevent the secondary reflection peak in the interfering multi-layer laminated film from appearing in the visible light region, which affects the photosynthesis.

[0196] In addition, the laminated film preferably has the following optical properties:

[0197] When the incident angle is 30°, the average transmittance at a wavelength of 450±20 nm is 80% or more, the average transmittance at a wavelength of 660±20 nm is 70% or more, and the average reflectance at a wavelength of 700 to 900 nm is 70% or more.

[0198] The average transmittance at a wavelength of 450±20nm when the incident angle is 30° may be, for example, 81% or more, 82% or more, 83% or more, 84% or more, 85% or more, 86% or more, 87% or more, 88% or more, or 89% or more, depending on the purpose of use and application. By setting the above configuration, it is effective to obtain the light transmission required for photosynthesis of plants.

[0199] The average transmittance at a wavelength of 660±20nm when the incident angle is 30° may be, for example, 71% or more, 72% or more, 73% or more, 74% or more, 75% or more, 76% or more, 77% or more, 78% or more, 79% or more, 80% or more, or 81% or more, depending on the purpose of use and application. By setting the above configuration, it is effective to obtain the light transmission required for photosynthesis of plants.

[0200] The average reflectivity at a wavelength of 700 nm or more and 900 nm or less at an incident angle of 30° may be, for example, 81% or more, 82% or more, 83% or more, 84% or more, 85% or more, 86% or more, 87% or more, 88% or more, 89% or more, 90% or more, 91% or more, 92% or more, 93% or more, 94% or more, 95% or more, 96% or more, 97% or more, or 98% or more, depending on the purpose of use and the application. By setting the above configuration, it is effective to obtain the light transmission required for photosynthesis of plants.

[0201] In addition, the laminated film preferably has the following optical properties:

[0202] When the incident angle is 0°, the average transmittance at a wavelength of 450±20 nm is 80% or more, the average transmittance at a wavelength of 660±20 nm is 70% or more, and the average reflectance at a wavelength of 700 nm to 900 nm is 70% or more.

[0203] The average transmittance at a wavelength of 450±20nm when the incident angle is 0° may be, for example, 81% or more, 82% or more, 83% or more, 84% or more, 85% or more, 86% or more, 87% or more, 88% or more, or 89% or more, depending on the purpose of use and application. By setting the above configuration, it is effective to obtain the light transmission required for photosynthesis of plants.

[0204] The average transmittance at a wavelength of 660±20nm when the incident angle is 0° may be, for example, 71% or more, 72% or more, 73% or more, 74% or more, 75% or more, 76% or more, 77% or more, 78% or more, 79% or more, 80% or more, 81% or more, 82% or more, 83% or more, 84% or more, 85% or more, or 86% or more, depending on the purpose of use and application. By setting the above configuration, it is effective to obtain the light transmission required for photosynthesis of plants.

[0205] The average reflectivity at a wavelength of 700 nm or more and 900 nm or less when the incident angle is 0 ° can be, for example, 71% or more, 72% or more, 73% or more, 74% or more, 75% or more, 76% or more, 77% or more, 78% or more, 79% or more, 80% or more, 81% or more, 82% or more, 83% or more, 84% or more, 85% or more, 86% or more, 87% or more, 88% or more, 89% or more, 90% or more, 91% or more, or 92% or more, depending on the purpose of use and the purpose of application. By setting the above-mentioned structure, the effect of heat insulation from sunlight can be obtained, which is effective. In addition, the influence on the reduction of photosynthesis caused by the appearance of the secondary reflection peak in the visible light region can be effectively prevented.

[0206] In addition, the ratio of the optical thickness of the above-mentioned laminated film is preferably more than 0.60 and less than 1.0. The ratio of the optical thickness of the above-mentioned laminated film is based on the purpose of use and the purpose, and the lower limit value can be, for example, more than 0.65, more than 0.67, more than 0.70, more than 0.75 or more than 0.8, and the upper limit value can be less than 0.99, less than 0.98, less than 0.97, less than 0.95, less than 0.93, less than 0.91 or less than 0.90. By being set to the above-mentioned structure, the secondary reflection peak in the interfering multi-layer laminated film can be effectively prevented from appearing in the visible light region, causing the influence on the reduction of photosynthesis. In addition, the optical thickness is determined according to the situation of the above-mentioned multi-layer laminated film.

[0207] When the laminated film of the present invention is used as a film for greenhouse horticulture, for example, it can fully supply plants with visible light that is a driving source for photosynthesis. Furthermore, it is believed that the laminated film of the present invention has a high total light transmittance and can therefore fully promote plant growth.

[0208] In addition, by having the above-mentioned structure, when the laminated film of the present invention is applied to a film for greenhouse gardening, for example, heat rays that raise the temperature in an agricultural greenhouse can be sufficiently blocked. Furthermore, since the heat release of a film itself, such as a heat ray absorbing film, is small, the temperature rise in the agricultural greenhouse can be suppressed, and the cost required for dehumidification cooling equipment can be reduced.

[0209] (Other layers)

[0210] The laminated film may be provided with other known films or layers as appropriate, unless the effects of the present invention are impaired, such as a slipperiness imparting layer and a diffusion layer.

[0211] For example, in order to further improve the slip properties of the laminated film, a slip property imparting layer having the function of imparting slip properties may be appropriately provided. In this case, the slip property imparting layer may be provided on at least one surface of the laminated film, preferably on both surfaces.

[0212] The above-mentioned slidability-imparting layer can be formed by coating a multi-layer laminate structure with a resin layer containing fine particles having an average particle size of 0.05 μm or more and 0.5 μm or a lubricant such as wax, or by laminating the multi-layer laminate structure by co-extrusion.

[0213] If the average particle size of the fine particles is less than 1.0 μm, the slip properties of the film tend to be insufficient due to the amount of particles, while if it is greater than 10 μm, the particles may fall off from the coating film, which is not preferred.

[0214] Examples of the fine particles include organic particles such as polystyrene, polymethyl methacrylate, methyl methacrylate copolymers, methyl methacrylate copolymer crosslinked bodies, polytetrafluoroethylene, polyvinylidene fluoride, polyacrylonitrile, benzoguanamine resins, and core-shell particles obtained by covering the outer shell of polystyrene particles with acrylic resins; and inorganic particles such as silicon dioxide, aluminum oxide, titanium dioxide, kaolin, talc, graphite, calcium carbonate, feldspar, molybdenum disulfide, carbon black, and barium sulfate. Among these, organic particles are preferred.

[0215] [Application of laminated films]

[0216] The laminated film of the present invention can be suitably used in the field of greenhouse horticulture, especially in coverings and curtains of outdoor facilities such as agricultural greenhouses that utilize sunlight (for example, in the first embodiment of the invention, in particular, in applications with opening and closing parts, folding parts, etc.).

[0217] The laminated film of the present invention can be used directly in the form of a film, or can be used after being appropriately processed. As a specific example of using the laminated film directly in the form of a film, a form of using the laminated film by sticking it to an object (e.g., a window material such as glass) can be cited. In addition, as a specific example of using the laminated film by processing it, a form of using it by making it into a woven / knitted fabric as shown below can be cited.

[0218] [Method for producing laminated thin film]

[0219] A method for producing a laminated thin film according to an embodiment of the present invention is described in detail. It should be noted that the production method shown below is an example, but the present invention is not limited thereto. In addition, different methods can also be obtained by referring to the following content.

[0220] The laminated film of the present invention comprises the above-mentioned multi-layer laminated films and has the above-mentioned optical properties.

[0221] First, a method for producing a multilayer laminated film will be described below by taking as an example a case where the multilayer laminated film has a multilayer laminated structure in which at least two types of resin layers having different refractive indices are alternately laminated.

[0222] The multilayer stacked structure of one embodiment of the present invention can be obtained by the following operation: using a multilayer feed block device, the polymer constituting the first layer and the polymer constituting the second layer are alternately overlapped in a molten state, for example, to form an alternating stacked structure with a total of more than 99 layers, and protective layers are provided on both sides thereof.

[0223] The multi-layer stacked structure can be stacked in such a way that the thickness of each layer of the first layer and the second layer has a desired inclined structure. This can be obtained by, for example, changing the interval and length of the slits in the multi-layer feed block device. Thus, light with a wavelength of 700 nm or more and 900 nm or less can be widely reflected.

[0224] After being stacked into the desired number of layers using the above method, it is extruded from a mold and cooled on a casting cylinder to obtain a multilayer unstretched film. The multilayer unstretched film is preferably stretched along at least a uniaxial direction (the uniaxial direction is the direction along the film surface) in the direction of the film-making mechanical axis (sometimes referred to as the longitudinal direction, length direction or MD) or in the direction orthogonal to it in the film surface (sometimes referred to as the transverse direction, width direction or TD). From the viewpoint of improving mechanical properties, it is more preferably stretched along the longitudinal and transverse biaxial directions. The stretching temperature is preferably carried out in the range of the glass transition temperature (Tg) to (Tg+20)°C of the polymer of the first layer. By stretching at a lower temperature than before, the orientation characteristics of the film can be more highly controlled.

[0225] Regarding the stretching ratio, it is preferred that the longitudinal and transverse stretching ratios are 2.0 to 6.5 times, and more preferably 3.0 to 5.5 times. Within this range, the larger the stretching ratio, the smaller the deviation of the refractive index in the plane direction of each layer in the first layer and the second layer will become due to the thinning achieved by stretching, and the light interference of the multilayer laminated structure is uniformed in the plane direction, and the difference in the refractive index in the stretching direction of the first layer and the second layer becomes larger, so it is preferred. As a stretching method, only longitudinal or transverse uniaxial stretching, sequential biaxial stretching of longitudinal and transverse stretching, and simultaneous biaxial stretching of longitudinal and transverse stretching can be applied. The longitudinal and transverse stretching methods can use known stretching methods such as heating stretching based on a rod-shaped heater, roller heating stretching, and tenter stretching. From the perspective of stretching speed and reducing damage caused by contact with rollers, tenter stretching is preferred.

[0226] In addition, by further heat-setting at a temperature of (Tg) to (Tg+30)°C after stretching and toeing in (relaxing) the structure in the stretching direction by 1 to 15%, the thermal stability (e.g., thermal shrinkage) of the resulting multilayer laminate structure can be highly controlled.

[0227] Next, a method for forming the surface functional layer will be described.

[0228] The surface functional layer is provided on at least one surface of the multi-layer laminated film, and may be provided directly on the multi-layer laminated film or via other layers.

[0229] The formation of the surface functional layer is not particularly limited, and examples thereof include a coating method, a spin coating method, and a transfer method, and formation by coating is preferred.

[0230] For example, as a method for forming a surface functional layer by coating the surface of a multi-layer laminated film, specifically, known coating techniques such as a rod coating method, a roller coating method, a knife-edge coating method, a gravure coating method, and a curtain coating method can be used. In addition, the multi-layer laminated film can be subjected to surface treatment (flame treatment, corona treatment, plasma treatment, ultraviolet treatment, etc.) before being coated with the surface functional layer. In addition, the coating liquid used in the coating is dispersed with the aforementioned particles and resin, and can be an aqueous dispersion or a dispersion dispersed by an organic solvent.

[0231] When the surface functional layer is formed by coating, coating of the multi-layer laminated film (multi-layer laminated structure) may be performed at any stage, but is preferably performed after the production process of the multi-layer laminated structure.

[0232] in addition, Figure 1 Schematic diagram showing an example of an agricultural greenhouse provided with the laminated film of the present invention. The agricultural greenhouse 1 utilizing sunlight has the laminated film 3 of the present invention deployed on the upper part, and a CO2 generator for supplying carbon dioxide to the interior of the agricultural greenhouse 1 as an optional unit is provided on the lower part. 2 The supply unit 2 and the dehumidification cooling unit 4 for cooling the interior of the agricultural greenhouse 1 are examples. In the agricultural greenhouse 1, for example, the skylight 5 can be closed during the day to economically maintain a high concentration of carbon dioxide in the agricultural greenhouse, and the skylight 5 can be opened at night to lower the temperature in the agricultural greenhouse.

[0233] <Woven / Knitted Fabrics>

[0234] The woven / knitted fabric of the present invention comprises thin strips cut out from the above-mentioned laminated film.

[0235] For example, in the first embodiment of the invention, the woven / knitted fabric of the present invention has the above-mentioned structure, so it does not block the growth of plants, has excellent heat insulation, and is particularly good in operability such as storage and foldability of the film. Therefore, it is particularly suitable as a woven / knitted fabric used in applications such as having an opening and closing portion, a folding portion, etc.

[0236] The woven / knitted fabric may include only the thin strips cut out from the laminated film, or may include other known strips or layers.

[0237] The woven / knitted fabric is, for example, a weft or warp knitted fabric obtained by using the thin strips. In addition, as another example, the woven / knitted fabric is a warp knitted fabric using the thin strips as insertion yarns.

[0238] The woven / knitted fabric may be a fabric obtained by, for example, weaving / knitting the thin strips cut out from the laminated film as warp or weft and woven / knitting the filament yarn or the like as weft or warp.

[0239] The woven / knitted fabric can improve the mechanical strength such as windability, blocking resistance, tear resistance, and durability of the laminated film, compared with the case where a film having only a heat ray reflecting layer is used alone.

[0240] Furthermore, the woven / knitted fabric can ensure air permeability by using the openings formed between the thin strips, filament yarns, etc. As described above, the woven / knitted fabric generally has excellent air permeability compared to the case where the laminated film is used alone, so it is possible to prevent the following situation: the temperature difference between the cultivation part and the ceiling part becomes large at night, especially in the early morning, and condensation is generated on the lower surface of the film to form water droplets and fall on the plants, causing discoloration / deterioration of the fruits, leaves, flowers, etc. of the plants.

[0241] In addition, the woven / knitted fabric has openings, so that excessive shielding of ultraviolet rays can be avoided. Avoiding excessive shielding of ultraviolet rays is sometimes effective for improving the coloring of fruits such as eggplants during growth and assisting the normal pollination activities of bees in agricultural greenhouses.

[0242] In addition, in the above-mentioned woven / knitted fabric, the thickness of the filament yarn or the like can be set to 0.01 to 0.30 times the width of the thin strip, and the interval between the adjacent thin strips can be set to 0.1 to 0.5 times the width of the thin strip. It should be noted that in the present invention, "filament yarn or the like" refers to filament yarn or spun yarn. The above-mentioned filament yarn can be any of monofilament yarn and multifilament yarn, without particular limitation.

[0243] In addition, if Figure 2 and Figure 3 As shown, it can be illustrated that the thin strip band (warp yarn) 11 obtained by cutting (cutting) the laminated film into thin strips is woven using filament yarns (weft yarns) 12. By setting the thickness A of the filament yarns (weft yarns) 12, the width B of the thin strip band (warp yarn) 11, the interval C of adjacent filament yarns (weft yarns) 12, and the interval D of adjacent thin strip bands (warp yarns) 11 to specific ranges, the opening rate of the woven / knitted fabric is within an appropriate range, and compared with the case of directly using the laminated film alone, while ensuring a high total light transmittance and heat ray reflectivity that are not inferior, the ultraviolet transmittance is within an appropriate range. In addition, in order to weave firmly, filament yarns (warp yarns) 13 of thickness E are sandwiched between adjacent thin strip bands (warp yarns) 11 as warp yarns.

[0244] More specifically, in the above-mentioned woven / knitted fabric, by setting the thickness of the filament yarn (weft yarn) 12 to 0.01 to 0.30 times the width of the thin strip (warp yarn) 11 and setting the interval between adjacent thin strips (warp yarns) 11 to 0.1 to 0.5 times the width of the thin strip (warp yarn) 11, the opening rate can be set to an appropriate range, and compared with the case of directly using a laminated film alone, it is possible to ensure a high total light transmittance and heat ray reflectivity while making the ultraviolet transmittance within an appropriate range. It should be noted that the interval between adjacent filament yarns (weft yarns) 12 is preferably in the range of 1.0 mm or more and 10 mm or less.

[0245] The width of the thin strips (warp yarns) 11 is preferably 1 mm or more and 10 mm or less, more preferably 2 mm or more and 6 mm or less, and further preferably 3 mm or more and 5 mm or less. The spacing between the thin strips (warp yarns) 11, that is, the distance between the end edges of adjacent thin strips (warp yarns) 11, is preferably 0.2 mm or more and 1.0 mm or less, more preferably 0.4 mm or more and 0.8 mm or less, and further preferably 0.5 mm or more and 0.7 mm or less. The thickness of the filament yarns (weft yarns) 12 is preferably 0.05 mm or more and 0.35 mm or less, more preferably 0.1 mm or more and 0.3 mm or less, and further preferably 0.15 mm or more and 0.25 mm or less. The woven / knitted fabric of the present invention can have an opening rate within an appropriate range by setting the width of the thin strips of the woven / knitted fabric, the thickness of the filament yarn, etc., the spacing between adjacent filament yarns, etc., and the spacing between adjacent thin strips as described above. Compared with the case of directly using a laminated film alone, it is possible to keep the ultraviolet transmittance within an appropriate range while ensuring an equally high total light transmittance and heat ray reflectance.

[0246] The porosity of the woven / knitted fabric formed by the laminated film is preferably set to 10% or more and 30% or less. It should be noted that the "porosity" in the present invention is calculated as follows: for a square portion (area 100 cm) with a length and width of 10 cm on one surface of the woven / knitted fabric, 2 ), when observing the surface of the part from the vertical direction of the surface, the part that can see the back side without any obstruction is regarded as an opening, and the total area of ​​the opening (called opening area) is calculated (Scm 2 ), using the formula: [S(cm 2 ) / 100(cm 2 )]×100 to find the answer.

[0247] In the woven / knitted fabric of the present invention, if the aperture ratio is 10% or more, the air permeability of the woven / knitted fabric can be improved. When the skylight provided in the ceiling is opened at night when photosynthesis is not carried out, the temperature in the agricultural greenhouse is lowered to prepare for the temperature rise during the next day, and the air heated during the day in the lower part of the agricultural greenhouse can be dissipated to the outside through the woven / knitted fabric. In addition, at night, especially in the early morning, even if the upper air near the roof is cooled, the following situation can be prevented: condensation generated on the lower surface of the woven / knitted fabric forms water droplets and falls on the plants, causing the fruits, leaves, flowers, etc. of the plants to change color, deteriorate, and other quality reductions, or the woven / knitted fabric itself to deteriorate, so it is preferred. In addition, if the aperture ratio is 30% or less, the high total light transmittance and heat ray reflectivity achieved by the laminated film can be ensured, so it is preferred.

[0248] <Film for greenhouse gardening>

[0249] The greenhouse gardening film of the present invention comprises the above-mentioned laminated film.

[0250] The above-mentioned greenhouse gardening film may include the above-mentioned laminated film, and may be composed of the above-mentioned laminated film alone, or may be provided with other known films, layers, and the like.

[0251] For example, in the first embodiment of the invention, the greenhouse gardening film of the present invention has the above-mentioned structure, so it does not block the growth of plants, has excellent heat insulation, and is particularly excellent in operability such as storage and foldability of the film. Therefore, it is particularly suitable as a greenhouse gardening film used in applications such as having an opening and closing portion, a folding portion, etc.

[0252] Example

[0253] Next, the present invention is specifically described by way of examples, but the present invention is not limited to the following examples. It should be noted that the physical properties and characteristics in the examples were measured or evaluated by the following methods. In addition, "parts" means "parts by mass".

[0254] In addition, each measurement / evaluation and the like in the examples were performed as follows.

[0255] (1) Overall film thickness and thickness of each layer

[0256] Regarding the overall thickness of the film, the film sample was clamped between a spindle detector (K107C manufactured by Anritsu Electric Co., Ltd.) and the thickness was measured at 10 different positions using a digital differential electronic micrometer (K351 manufactured by Anritsu Electric Co., Ltd.). The average value was calculated as the overall thickness of the film.

[0257] Regarding the thickness of each layer of the film, the laminated film was cut into 2 mm in the film length direction and 2 cm in the width direction and fixed to the embedding capsule, and then embedded using epoxy resin (REFINETEC, EpoMount). The embedded sample was cut perpendicularly to the width direction with a slicer (LEICA, ULTRACUT UCT) to make a 5 nm thick film slice. A transmission electron microscope (Hitachi S-4300) was used to observe and photograph at an accelerating voltage of 100 kV, and the thickness (physical thickness) of each layer was measured based on the photograph.

[0258] For a layer having a thickness exceeding 1 μm, the portion existing inside the multilayer structure was defined as an intermediate layer, and the portion existing on the outermost layer was defined as an outermost layer, and the thicknesses of the respective layers were measured.

[0259] It should be noted that the first layer or the second layer can be determined by the refractive index, but when it is difficult to make such a determination, it can also be determined based on the electronic state based on NMR analysis or TEM analysis. In addition, the refractive index of each layer can also be obtained based on a single-layer film with the same composition as each layer and increased thickness.

[0260] (2) Spectral transmittance

[0261] The spectral transmittance was measured at a wavelength of 300 nm or more and 1800 nm or less using a spectrophotometer (MPC-3100 manufactured by Shimadzu Corporation) at intervals of 2 nm. The spectral spectrum of the obtained laminated film was obtained, and the spectral transmittance of each wavelength was measured. In addition, the average transmittance in each wavelength range in the example was calculated.

[0262] The measurement was performed in an air atmosphere at 25° C., and the incident angle of the measurement light was set to 0° or 30°.

[0263] (3) Spectral reflectivity

[0264] The BaSO was measured using a spectrophotometer (MPC-3100, manufactured by Shimadzu Corporation) within a wavelength range of 300 nm to 1800 nm. 4 The reflectance when a white plate is taken as 100%. The spectral spectrum of the obtained film was obtained, and the average reflectance in each wavelength range was determined.

[0265] (4) Refractive index

[0266] The refractive index of the polyester constituting the first layer and the second layer was determined by measuring at a wavelength of 633 nm using a prism coupler manufactured by Metricon Inc. The refractive index of each layer was measured by peeling off the film interface so that the layer was exposed on the surface.

[0267] (5) Ring stiffness

[0268] As samples for measuring the ring stiffness, each laminated film prepared in the examples and comparative examples was cut into a strip film with a width of 25.4 mm and a length of 130 mm, wherein the longitudinal direction of the strip film was aligned with the direction of the measurement object.

[0269] The cut strip film was mounted on a ring stiffness tester (manufactured by Toyo Seiki Co., Ltd.) and the ring-shaped rebound force generated by the resistance to crushing was measured when the chuck spacing was 50 mm and the compression speed was 3.3 mm / s (refer to Figure 4 The value obtained by dividing the maximum value of the repulsive force obtained by the measurement by the width is defined as the ring stiffness (mN / cm).

[0270] It should be noted that the ring stiffness refers to the rebound force of a ring measured when a ring is formed by a film cut into strips of a specified size and pressed radially by a specified amount, which is an indicator of the film stiffness. The larger the value of the ring stiffness, the higher the film stiffness, and the smaller the value, the lower the film stiffness. When used for agricultural greenhouses, for example, it is easy to achieve operability and storage when opening and closing.

[0271] Using each of the above samples, rigidity evaluation was performed based on ring rigidity, and the effect of operability was evaluated according to the following criteria.

[0272] ◎: Less than 45.0 mN / cm (good effect due to low rigidity)

[0273] ○: 45.0 mN / cm or more and less than 50.0 mN / cm (the effect of low rigidity is slightly better)

[0274] △: 50.0mN / cm or more

[0275] <Invention method 1>

[0276] [Example 1]

[0277] [Production of multi-layer laminated polyester film]

[0278] As the polyester for the first layer and the protective layer, polyethylene 2,6-naphthalate (hereinafter referred to as "PEN") having an intrinsic viscosity (o-chlorophenol, 35°C) of 0.62 dl / g was prepared, and as the polyester for the second layer, cyclohexanedimethanol copolymerized polyethylene terephthalate (hereinafter referred to as "PETG") having an intrinsic viscosity (o-chlorophenol, 35°C) of 0.77 dl / g copolymerized with 30 mol% of cyclohexanedimethanol was prepared.

[0279] The polyester used for the first layer and the protective layer was dried at 180°C for 5 hours and then supplied to the extruder, and the PEN of the first layer was molten at 290°C. The PETG of the second layer was dried at 120°C for 10 hours and then supplied to the extruder and heated to 230°C to be molten.

[0280] Thereafter, a multilayer feed block device was used to stack the PEN layer of the first layer and the PETG layer of the second layer alternately after the PEN of the first layer was branched out into 137 layers and the PETG of the second layer was branched out into 138 layers, and the ratio of the maximum layer thickness to the minimum layer thickness of each of the first layer and the second layer was continuously changed to 1.4 times in terms of maximum / minimum, and a protective layer was stacked on both sides of the stacked structure. The film was introduced into the mold while maintaining the stacked state, and cast on a casting cylinder. Thus, an unstretched multilayer laminated film having a protective layer formed by a PEN layer on the outermost layer of both sides of the film and a total number of layers of the stacked structure of 275 layers was produced. It should be noted that, with respect to the thickness of the protective layer, the supply amount was adjusted in such a manner that the thickness after stretching is as described in Table 1. In addition, the resin discharge amount of the first layer and the second layer was adjusted in such a manner that the optical thickness ratio of the first layer and the second layer of the stacked structure after removing the protective layer is equal.

[0281] The unstretched film obtained by the above operation was preheated at 120°C, and further heated with a 900°C IR heater from 15mm above between low-speed and high-speed rollers, and stretched to 3.5 times in the longitudinal direction. Then, it was supplied to a tenter and stretched to 4.5 times in the transverse direction at 140°C. After the obtained biaxially oriented film was heat-set at a temperature of 190°C for 30 seconds, 1.5% of the inner beam (relaxation) was implemented in the transverse direction. The average refractive index in the plane after the film was made using the resin of the first layer was 1.760. In addition, the average refractive index in the plane after the film was made using the resin of the second layer was 1.580.

[0282] The total thickness of the obtained multilayer laminated polyester film is 50 μm, and the multilayer laminated portion is 35 μm. The total thickness is set to 50 μm by setting the thickness of the protective layer on the surface and the back to 7.5 μm respectively. The surface mentioned here is the casting roll side (Front surface, front), and the back side is the opposite side (Back surface, back). Unless otherwise specified, the thickness of the protective layer on the surface and the back is set to the same thickness. It should be noted that these thicknesses can be adjusted by adjusting the supply amount, the ejection amount of the first layer and the second layer, and the flow path diameter.

[0283] The transmittance of the obtained multilayer laminated polyester film at an incident angle of 0° at a wavelength of 700 nm was 76.5%, and the transmittances at other wavelengths are shown in Table 1. Table 1 also shows the layer constitution, film forming conditions, and physical properties of the obtained film.

[0284] [Examples 2 to 13, Comparative Example 1]

[0285] The same operation as in Example 1 was repeated except that the thickness of the protective layer, the thickness of the multilayer laminated portion, and the ratio of the optical thickness were adjusted as shown in Table 1. The same evaluation as in Example 1 was performed on the obtained film.

[0286] The above-mentioned mixing ratios and the above-mentioned results are shown in Table 1 below.

[0287] [Table 1]

[0288]

[0289] It can be seen from Table 1 that the laminated film of the embodiment of the present invention has high visible region transmittance compared with the film of the comparative example, does not block the growth of plants, can effectively cut off the near-ultraviolet region with high solar thermal energy, and has excellent heat insulation and operability.

[0290] <Invention method 2>

[0291] [Example 1]

[0292] [Production of multi-layer laminated polyester film]

[0293] As the polyester for the first layer and the protective layer, polyethylene 2,6-naphthalate (hereinafter referred to as "PEN") having an intrinsic viscosity (o-chlorophenol, 35°C) of 0.62 dl / g was prepared, and as the polyester for the second layer, cyclohexanedimethanol copolymerized polyethylene terephthalate (hereinafter referred to as "PETG") having an intrinsic viscosity (o-chlorophenol, 35°C) of 0.77 dl / g copolymerized with 30 mol% of cyclohexanedimethanol was prepared.

[0294] The polyester used for the first layer and the protective layer was dried at 180°C for 5 hours and then supplied to the extruder, and the PEN of the first layer was molten at 290°C. The PETG of the second layer was dried at 120°C for 10 hours and then supplied to the extruder and heated to 230°C to be molten.

[0295] Thereafter, a multilayer feed block device was used to stack the PEN layer of the first layer and the PETG layer of the second layer alternately after the PEN of the first layer was branched out into 137 layers and the PETG of the second layer was branched out into 138 layers, and the ratio of the maximum layer thickness to the minimum layer thickness of each of the first layer and the second layer was continuously changed to 1.4 times in terms of maximum / minimum, and a protective layer was stacked on both sides of the stacked structure. The film was introduced into the mold while maintaining the stacked state, and cast on a casting cylinder. Thus, an unstretched multilayer laminated film having a protective layer formed by a PEN layer on the outermost layer of both sides of the film and a total number of layers of the stacked structure of 275 layers was produced. It should be noted that, with respect to the thickness of the protective layer, the supply amount was adjusted in such a manner that the thickness after stretching is as described in Table 1. In addition, the resin discharge amount of the first layer and the second layer was adjusted in such a manner that the optical thickness ratio of the first layer and the second layer of the stacked structure after removing the protective layer is equal.

[0296] The unstretched film obtained by the above operation was preheated at 120°C, and further heated with a 900°C IR heater from 15 mm above between low-speed and high-speed rollers, and stretched to 3.5 times in the longitudinal direction. Then, it was supplied to a tenter and stretched to 4.5 times in the transverse direction at 140°C. The obtained biaxially oriented film was heat-set at a temperature of 190°C for 30 seconds, and then subjected to 1.5% toe-in (relaxation) in the transverse direction.

[0297] The total thickness of the obtained multilayer laminated polyester film is 50 μm, and the multilayer laminated portion is 35 μm. The total thickness is set to 50 μm by setting the thickness of the protective layer on the surface and the back to 7.5 μm respectively. The surface mentioned here is the casting roll side (Front surface), and the back side is the opposite side (Back surface). Unless otherwise specified, the thickness of the protective layer on the surface and the back is set to the same thickness. It should be noted that these thicknesses can be adjusted by adjusting the supply amount, the ejection amount of the first layer and the second layer, and the flow path diameter.

[0298] The transmittance of the obtained multilayer laminated polyester film at an incident angle of 0° at a wavelength of 700 nm was 76.5%, and the transmittances at other wavelengths are shown in Table 1. Table 1 also shows the layer constitution, film forming conditions, and physical properties of the obtained film.

[0299] [Examples 2 to 12, Comparative Examples 1 to 3]

[0300] The same operation as in Example 1 was repeated except that the thickness of the protective layer, the thickness of the multilayer laminated portion, and the ratio of the optical thickness were adjusted as shown in Table 1. The same evaluation as in Example 1 was performed on the obtained film.

[0301] The above-mentioned mixing ratios and results are shown in Table 2 below.

[0302] [Table 2]

[0303]

[0304] It can be seen from Table 2 that the laminated film of the embodiment of the present invention has high visible region transmittance compared with the film of the comparative example, does not block the growth of plants, can effectively cut off the near-ultraviolet region with high solar thermal energy, and has excellent heat insulation.

Claims

1. A laminated film, which is a laminated film for agricultural greenhouses utilizing sunlight, The laminated film comprises a multilayer laminated film obtained by alternately laminating at least two resin layers having different refractive indices along a thickness direction, and has the following optical properties: When the incident angle is 0°, the average transmittance of wavelengths from 430 nm to 680 nm is 70% or more, and the average reflectance of wavelengths from 800 nm to 1100 nm is less than 80%. The multi-layer laminate film has a stiffness of less than 50.0 mN / cm.

2. The laminated film according to claim 1, wherein The laminated film has the following optical properties: When the incident angle is 30°, the average reflectivity at a wavelength of 700 nm to 900 nm is 70% or more.

3. The laminated film according to claim 1, wherein The laminated film has the following optical properties: When the incident angle is 30°, the average transmittance at a wavelength of 450±20nm is 80% or more, the average transmittance at a wavelength of 660±20nm is 70% or more, and the average reflectance at a wavelength of 700nm to 900nm is 70% or more.

4. The laminated film according to claim 1, wherein The laminated film has the following optical properties: When the incident angle is 0°, the average transmittance at a wavelength of 450±20 nm is 80% or more, the average transmittance at a wavelength of 660±20 nm is 70% or more, and the average reflectance at a wavelength of 700 nm to 900 nm is 70% or more.

5. A laminated film, which is a laminated film for agricultural greenhouses utilizing sunlight, The laminated film comprises a multilayer laminated film obtained by alternately laminating at least two resin layers having different refractive indices along a thickness direction, and has the following optical properties: When the incident angle is 0°, the average transmittance at a wavelength of 430 nm to 680 nm is 80% or more, and the average reflectance at a wavelength of 800 nm to 1100 nm is less than 70%.

6. The laminated film according to claim 5, wherein The laminated film has the following optical properties: When the incident angle is 30°, the average transmittance at a wavelength of 450±20nm is 80% or more, the average transmittance at a wavelength of 660±20nm is 70% or more, and the average reflectance at a wavelength of 700nm to 900nm is 70% or more.

7. The laminated film according to claim 5, wherein The laminated film has the following optical properties: When the incident angle is 0°, the average transmittance at a wavelength of 450±20 nm is 80% or more, the average transmittance at a wavelength of 660±20 nm is 70% or more, and the average reflectance at a wavelength of 700 nm to 900 nm is 70% or more.

8. The laminated film according to claim 1, wherein The optical thickness ratio of the multi-layer laminated film is 0.60 or more and less than 1.

0.

9. The laminated film according to claim 4, wherein The optical thickness ratio of the multi-layer laminated film is 0.60 or more and less than 1.

0.

10. The laminated film according to claim 1, wherein The laminated film includes an ultraviolet absorbing layer on at least one surface.

11. The laminated film according to claim 4, wherein The laminated film includes an ultraviolet absorbing layer on at least one surface.

12. A woven / knitted fabric comprising thin strips cut out from the laminate film according to any one of claims 1 to 11.

13. A woven / knitted fabric, which is woven / knitted using thin strips cut out from the laminated film according to any one of claims 1 to 11 as warp yarns or weft yarns and using filament yarns or spun yarns as warp yarns or weft yarns. 14 . A film for greenhouse gardening, comprising the laminated film according to claim 1 .

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