Agricultural polyolefin-based multilayer film

Abstract

To provide an agricultural polyolefin-based multilayer film which has transparency and has excellent heat shielding property and heat retaining property.SOLUTION: An agricultural polyolefin-based multilayer film has at least an outer layer, an intermediate layer, and an inner layer, and satisfies requirements 1 to 4.

Description

[Technical Field]

[0001] The present invention relates to a polyolefin-based multilayer film for agricultural use, and more particularly to a polyolefin-based multilayer film for agricultural use that is transparent and has excellent heat-shielding and heat-retaining properties. [Background technology]

[0002] In order to semi-force or retard the cultivation of agricultural crops and increase their marketability and productivity, greenhouse cultivation and tunnel cultivation, in which useful plants are grown under a cover of agricultural covering materials, are becoming increasingly common. Currently, vinyl chloride resins or polyolefin resins are mainly used as agricultural films, but agricultural polyolefin resin films mainly made of polyolefin resins are becoming more widely used because they are lighter than vinyl chloride resins due to their lower density, produce fewer toxic gases when incinerated, and can be produced inexpensively in wide widths using inflation molding, eliminating the need for adhesive processing for width joining.

[0003] Furthermore, in recent years, rising summer temperatures have become a problem due to the effects of global warming, while summer cultivation is becoming increasingly important from the perspective of improving land use efficiency. On sunny summer days, the temperature on the upper surface of greenhouses can rise to around 50°C, and it is necessary to maintain the temperature inside the greenhouse within a range that allows crops to grow. Therefore, in the case of perennial flowers that need to survive the summer, shading netting or cheesecloth is used as inner or outer curtains to block about 30-80% of the sunlight (including visible light), reducing the amount of solar energy that penetrates into the greenhouse and preventing the temperature inside from rising.Although flowers can be grown even with a low light requirement, there is the problem of the plants growing too tall due to shading.

[0004] In addition, greenhouses are also cooled to combat the high temperatures of summer, but mist cooling has not become widespread due to problems such as the fact that it makes plants more susceptible to disease when they get wet, the high humidity worsens the working environment, and its effectiveness is insufficient in hot and humid environments such as Japan.On the other hand, cooling with a refrigerator is also not widely used in greenhouses exposed to sunlight, as its cooling efficiency is very low. On the other hand, when it comes to growing fruit and vegetables in the summer, shading is almost impossible due to crop physiology and quality concerns, so in the warm southwestern regions, fruit and vegetable cultivation in greenhouses is not carried out in the summer.Even in the cooler regions of Tohoku and Hokkaido, the temperature inside the greenhouses becomes so high in the summer when covered with transparent film that it causes problems with quality and the working environment. Therefore, there is a demand for a type of covering material that transmits visible light as much as possible and blocks heat rays (i.e., near-infrared rays) as much as possible.

[0005] As an agricultural film to solve such problems, for example, an outdoor extension film has been proposed in which a layer containing specific inorganic oxide microparticles and an ultraviolet absorber is provided on at least one side of a thermoplastic resin film by coating or the like (see Patent Documents 1 and 2).

[0006] The heat ray absorbing or reflecting agent made of inorganic oxide microparticles disclosed in Patent Document 1 and the like has a problem in that when exposed outdoors, its heat ray shielding ability (heat-shielding property) decreases within several years, and it becomes less effective as a countermeasure against high temperatures inside greenhouses in summer. In Patent Document 1 and the like, it was possible to prevent the deterioration of heat-shielding property over time by incorporating an ultraviolet absorber into the coating layer containing inorganic oxide microparticles, but the coating layer peels off when the film is stretched out for a long period of time, making it difficult to achieve long-term heat-shielding property.

[0007] Furthermore, a technology has been proposed for agricultural films that can sufficiently transmit light rays with wavelengths in the visible light range without excessively transmitting light rays with wavelengths in the infrared light range by incorporating titanium oxide of a specific particle size into a thermoplastic resin film (Patent Document 3, etc.). However, the technology disclosed in Patent Document 3, etc., does not yet provide a sufficient level of heat-shielding performance, and further improvements in performance are desired.

[0008] On the other hand, agricultural films are required to achieve heat insulation, particularly in the summer, while at the same time avoiding poor growth due to insufficient light or temperature in the winter, and a balance of these performance characteristics is required. Specifically, in agricultural greenhouses and the like, the ground absorbs heat from sunlight during the day and releases this heat into the interior of the greenhouse at night. This radiant heat must be prevented from dissipating outside the greenhouse, and the soil and air temperatures inside the greenhouse must be kept as low as possible at night, so that the films must have sufficient heat retention properties.

[0009] Although various technologies related to heat-shielding agricultural films as described above have been proposed to date, no agricultural film that is transparent and has excellent heat-shielding and heat-retaining properties has yet been put into practical use. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] Patent No. 3787947 [Patent Document 2] Patent No. 3787948 [Patent Document 3] Japanese Patent Application Laid-Open No. 2006-314218 DISCLOSURE OF THE INVENTION [Problem to be solved by the invention]

[0011] An object of the present invention is to provide a polyolefin-based multilayer film for agricultural use that is transparent and has excellent heat-shielding and heat-retaining properties.

[0012] As a result of extensive research, the present inventors have found that when an inorganic microparticle dispersion containing cesium-doped tungsten oxide is contained in at least one of the outer, intermediate, and inner layers of an agricultural polyolefin multilayer film and the film has specific optical properties, it is possible to provide an agricultural film that is transparent and has both heat-shielding and heat-retaining properties, and have completed the present invention.

[0013] That is, the present invention has the following configuration. [1] A polyolefin-based multi-layer agricultural film having at least an outer layer, an intermediate layer, and an inner layer, and satisfying the following requirements: (Requirement 1) At least one of the outer layer, intermediate layer, and inner layer contains an inorganic fine particle dispersion containing one or more types of inorganic fine particles selected from the following: (i) Cesium-doped tungsten oxide (ii) Cesium-doped tungsten oxide and titanium oxide-containing particles (Requirement 2) The average transmittance in the wavelength range of 400 to 700 nm is 75% or more. (Requirement 3) The average transmittance in the wavelength range of 800 to 2500 nm is 75% or less. (Requirement 4) The average transmittance in the wavelength range of 4 to 25 μm is 45% or less. [2] The agricultural polyolefin multilayer film according to [1], which further satisfies the following requirements: (Requirement 5) The average transmittance in the wavelength range of 4 to 25 μm corrected by the radiation distribution of blackbody radiation at 15°C is 35% or less. [3] The agricultural polyolefin-based multilayer film according to [1], wherein the intermediate layer contains the inorganic fine particle dispersion. [4] The agricultural polyolefin multilayer film according to [1], wherein at least an intermediate layer contains hydrotalcites. [Effects of the Invention]

[0014] According to the present invention, it is possible to provide a polyolefin-based multilayer film for agricultural use that is transparent and has excellent heat-shielding and heat-retaining properties. [Brief explanation of the drawings]

[0015] [Figure 1] An overview of the heat insulation test equipment is shown. DETAILED DESCRIPTION OF THE INVENTION

[0016] One embodiment of the present invention is a polyolefin-based multilayer film for agricultural use (hereinafter also referred to as "the polyolefin-based multilayer film for agricultural use of the present invention") that has at least an outer layer, an intermediate layer, and an inner layer and satisfies the following requirements: (Requirement 1) At least one of the outer layer, intermediate layer, and inner layer contains an inorganic fine particle dispersion containing one or more types of inorganic fine particles selected from the following: (i) Cesium-doped tungsten oxide (ii) Cesium-doped tungsten oxide and titanium oxide-containing particles (Requirement 2) The average transmittance in the wavelength range of 400 to 800 nm is 75% or more. (Requirement 3) The average transmittance in the wavelength range of 800 to 2500 nm is 75% or less. (Requirement 4) 400~2500cm -1 The average transmittance in the wavelength range is 45% or less.

[0017] (1) Polyolefin multilayer film The agricultural polyolefin multilayer film of the present invention is composed of at least three layers, namely, an outer layer, an intermediate layer, and an inner layer, but may include more layers. In the present invention, when the agricultural polyolefin multilayer film is spread in a greenhouse, the layer facing the outside of the greenhouse is referred to as the outer layer, and the layer facing the inside of the greenhouse is referred to as the inner layer.

[0018] In one aspect of the agricultural polyolefin-based multilayer film of the present invention, the outer layer and the inner layer contain at least one selected from linear low-density polyethylene, low-density polyethylene, and an ethylene-vinyl acetate copolymer having a low vinyl acetate content. In the present invention, by making the outer layer and the inner layer have such a resin composition, it is possible to suppress stickiness between the films and fusion of the film with components of a pipe greenhouse, etc.

[0019] Examples of linear low-density polyethylene include so-called ethylene-α-olefin copolymers such as ethylene-propylene copolymer, ethylene-butene copolymer, ethylene-4-methyl-1-pentene copolymer, ethylene-1-hexene copolymer, ethylene-octene copolymer, etc. As the linear low-density polyethylene, any of those obtained using a Ziegler catalyst, those obtained using a Phillips catalyst, those obtained using a metallocene catalyst, etc. can be used.

[0020] Linear low-density polyethylene obtained using a metallocene catalyst can be obtained, for example, by (Method A) (Japanese Patent Laid-Open Nos. 58-19309, 59-95292, and 60-35005, etc.) or (Method B) (Japanese Patent Laid-Open Nos. 6-9724, 6-136195, and 6-136196, etc.).

[0021] In terms of obtaining a film with good initial transparency and transparency sustainability, linear low-density polyethylene polymerized using a metallocene compound can be used without being bound by the above methods (A) and (B).

[0022] Low-density polyethylene is usually produced by the high-pressure radical method, where it is polymerized under high pressure and high temperature conditions. Its density is 0.910-0.930 g / cm. 3 However, when considering the balance of film formability, flexibility, transparency, strength, etc., the 0.92 g / cm 3 Densities of the same or different values can be preferably used.

[0023] The ethylene-vinyl acetate copolymer that can be contained in the outer layer and inner layer of the present invention preferably has a vinyl acetate content in the range of 1 to 10 wt %, more preferably 2 to 8 wt %. Here, the vinyl acetate content is a value when the weight of the ethylene-vinyl acetate copolymer is taken as 100 wt %. A vinyl acetate content in the above range is preferable because it can prevent the film from sticking to itself when exposed to a high-temperature environment and from fusing with components of a pipe house, etc.

[0024] The outer layer and the inner layer may contain a resin other than linear low-density polyethylene, low-density polyethylene, or ethylene-vinyl acetate copolymer having a vinyl acetate content of 1 to 10% by weight, as long as the effects of the present invention are not impaired. As such other resin, any resin other than those mentioned above can be used as long as it does not impair the effects of the present invention.

[0025] In one aspect of the agricultural polyolefin-based multilayer film of the present invention, the types and compositions of the resins contained in the outer layer and the inner layer may be the same or different.

[0026] In one aspect of the agricultural polyolefin multilayer film of the present invention, the intermediate layer contains an ethylene-vinyl acetate copolymer (A) having a vinyl acetate content of 1 to 20% by weight, where the vinyl acetate content is the value when the weight of the ethylene-vinyl acetate copolymer (A) is taken as 100% by weight, and is preferably 1 to 20% by weight, and more preferably 2 to 18% by weight. On the other hand, if the vinyl acetate content is greater than 20% by weight, the melting point of the ethylene-vinyl acetate copolymer drops to 80°C or below, which is undesirable because the film becomes sticky when exposed to a high-temperature environment, its blocking resistance deteriorates, and the film may fuse to pipe greenhouse components after being stretched. Therefore, by setting the vinyl acetate content in the range of 1 to 20% by weight, a balance can be achieved between the effect of reducing transparency at high temperatures and the effect of preventing blocking resistance and film fusion at high temperatures.

[0027] The intermediate layer may contain a resin other than the ethylene-vinyl acetate copolymer (A) as long as the effects of the present invention are not impaired. Any resin can be selected as such other resin as long as the effects of the present invention are not impaired.

[0028] (2) Inorganic fine particle dispersion Requirement 1 The agricultural polyolefin-based multilayer film of the present invention contains, in at least the outer layer or inner layer, an inorganic fine particle dispersion containing one or more types of inorganic fine particles selected from the following: (i) Cesium-doped tungsten oxide (ii) Cesium-doped tungsten oxide and titanium oxide-containing particles

[0029] That is, in the agricultural polyolefin-based multi-layer film of the present invention, it is important that at least one of the outer, intermediate and inner layers contains a metal oxide dispersion containing cesium-doped tungsten oxide. Cesium-doped tungsten oxide is known to have good heat-shielding properties, and technologies have been proposed for heat-shielding agricultural films in which a coating film containing cesium-doped tungsten oxide and a resin such as an acrylic resin is laminated onto a base resin film such as a polyolefin film (e.g., JP 2019-83749 A). However, when films using such technologies are deployed outdoors, they are exposed to wind and rain due to their outdoor specifications, causing the coating film to thin over time, resulting in a significant decrease in heat-shielding performance. On the other hand, it is also possible to add cesium-doped tungsten oxide to a base resin film such as a polyolefin-based film. However, cesium-doped tungsten oxide is a very expensive material, and although it has the advantage of being safer than the relatively inexpensive antimony-doped tin oxide, it is rarely used in practice as an agricultural heat-shielding material. According to the studies of the present inventors, the dispersibility of cesium-doped tungsten oxide particles in resins is insufficient, and therefore sufficient heat-shielding performance cannot be obtained in proportion to the amount added, making them unsuitable for use in agricultural heat-shielding materials. As a result of intensive studies, the present inventors have found that a film that combines transparency and heat-shielding properties can be obtained by adding, to a polyolefin-based laminate film, an inorganic fine particle dispersion containing cesium-doped tungsten oxide particles with improved dispersibility, specifically, cesium-doped tungsten oxide particles described below. On the other hand, conventional agricultural heat-shielding materials often use inexpensive materials such as titanium oxide, and are designed as light-shielding materials rather than heat-shielding materials, which makes them problematic for year-round use in greenhouses, especially in winter when light and heat are needed. In other words, materials designed for summer heat shielding may not be suitable for use in greenhouses in winter, and a concrete solution was needed for agricultural heat shielding materials that could be used all year round without replacement. Therefore, the inventors conducted extensive research and discovered what specific heat-shielding material and film properties should be used to enable use not only for heat shielding in the summer but also for heat retention in the winter. As a result, they were able to specifically realize an agricultural heat-shielding material that is excellent in transparency, heat-shielding properties, and heat retention, thereby completing the present invention.

[0030] (i) Cesium-doped tungsten oxide The cesium tungstate forming the cesium-doped tungsten oxide particles (cesium tungstate particles; also abbreviated as "CWO particles") is not particularly limited, but examples thereof include Cs 0.33 An example is cesium-doped tungsten oxide represented by the formula WO3, but is not limited to this.

[0031] The CWO particles are preferably metal oxide particles having an average primary particle size of 10 to 100 nm, and more preferably 10 to 80 nm from the viewpoint of transparency. When the content is within this range, the polyolefin-based multilayer film obtained by using the inorganic fine particle dispersion of the present invention can have excellent transparency.

[0032] The average primary particle size of CWO particles can be determined directly from the image obtained by observing them with a scanning electron microscope.

[0033] The shape of the CWO particles is not particularly limited, but may be spherical, rod-like, cylindrical, ring-like, plate-like, plate-like laminate, hollow sphere, porous particle, etc., and a spherical shape with excellent fluidity is preferred unless changing the shape would result in the development of a new function.

[0034] The inorganic fine particles (i) to (ii) used in the present invention are preferably used as an inorganic fine particle dispersion containing the inorganic fine particles, an organosilane compound having an alkyl group and an alkoxysilyl group, and a wax that is solid at 23° C. When such a dispersion is mixed with a thermoplastic resin, it can have excellent stability and processability. In particular, it is preferable to coat the surfaces of the inorganic fine particles (i) to (ii) with an organic silane compound having an alkyl group and an alkoxysilyl group, and then mix a wax that is solid at 23°C to form an inorganic fine particle dispersion, which can further improve the affinity with the wax and thermoplastic resin and produce a multilayer film with excellent stability and processability. This makes the surfaces of the inorganic fine particles hydrophobic, thereby suppressing hydrolysis of the wax and thermoplastic resin during processing, thereby maintaining a high intrinsic viscosity of the inorganic fine particle dispersion, and thereby further improving the processing stability and strength of the multilayer film.

[0035] As an inorganic fine particle dispersion containing CWO particles, for example, "TET 1KS 174 NAT" manufactured by Toyo Color Co., Ltd.: 5 wt % masterbatch can be used.

[0036] (ii) Cesium-doped tungsten oxide and titanium oxide-containing particles The agricultural polyolefin multi-layer film of the present invention may contain, as inorganic fine particles, titanium oxide-containing particles in addition to the cesium-doped tungsten oxide particles. Titanium oxide has the property of blocking sunlight, so by using it in combination with CWO particles, the heat-shielding properties can be further improved. In the present invention, the titanium oxide-containing particles include particles consisting of titanium oxide alone (titanium oxide particles) and inorganic particles coated with titanium oxide, for example, mica particles coated with titanium oxide (titanium oxide-coated mica).

[0037] Titanium oxide (titanium oxide particles) has the property of blocking sunlight, so by using it in combination with ATO particles, the heat-shielding properties can be further improved. Examples of titanium oxide include rutile titanium oxide and anatase titanium oxide.

[0038] The particle size of titanium oxide is preferably a weight average particle size of 0.6 to 1.5 μm.

[0039] Furthermore, titanium oxide-containing particles that can be used in combination with ATO particles include mica particles coated with titanium oxide (titanium oxide-coated mica). Mica particles have excellent transparency and a strong light scattering effect, and so by incorporating titanium oxide-coated mica, it is possible to enhance the heat-shielding effect on agricultural greenhouses, etc., particularly the effect of suppressing temperature increases in the upper parts.

[0040] The titanium oxide-coated mica particles have a 10% particle size of preferably 3 μm or more, more preferably 5 μm or more, since a smaller particle size reduces the heat ray shielding effect. Also, a larger particle size of 90% reduces the transparency and strength of the heat shield sheet, so the particle size is preferably 80 μm or less, more preferably 65 μm or less.

[0041] In the present invention, the 10% particle size of the titanium oxide-coated mica particles refers to the particle size distribution of the titanium oxide-coated mica particles to be measured by laser diffraction, and in the weight-based particle size distribution of the obtained titanium oxide-coated mica particles, the particle size is measured at 10% cumulative from the titanium oxide-coated mica particles with the smallest particle size to the titanium oxide-coated mica particles with the largest particle size. Similarly, the 90% particle size refers to the particle size at 90% cumulative.

[0042] The titanium oxide coverage in the present invention refers to the mass ratio of the titanium dioxide content in the mica whose surface is coated with titanium oxide. In the titanium oxide-coated mica particles, if the coverage of mica with titanium oxide is low, the heat-shielding effect may be insufficient, while if the coverage exceeds 70%, the heat-shielding effect does not increase, so the coverage is preferably 10 to 70%, more preferably 30 to 60%. Furthermore, any of the rutile, anatase, and brookite types of titanium oxide can be suitably used to cover mica.

[0043] The titanium oxide-coated mica particles are commercially available, for example, under the trade names Mearlin Exterior Fine Red 439V, Mearlin Fine Violet 539V, Mearlin Super Violet 9530Z, Mearlin Exterior CFS Super Violet 5303Z (all manufactured by BASF), Iriotec 9770, Iriodin 223, Iriodin 100, and Iriodin 120 (all manufactured by Merck).

[0044] When cesium-doped tungsten oxide and titanium oxide-containing particles are used, as described in (i), they are preferably used as an inorganic fine particle dispersion containing CWO particles, titanium oxide-containing particles, an organosilane compound having an alkyl group and an alkoxysilyl group, and a wax that is solid at 23° C. When such a dispersion is mixed with a thermoplastic resin, it can be made to have excellent stability and processability. In particular, it is preferable to coat the surfaces of CWO particles and titanium oxide-containing particles with an organosilane compound having an alkyl group and an alkoxysilyl group, and then mix in a wax that is solid at 23°C to form an inorganic fine particle dispersion, which can further improve the affinity with the wax and thermoplastic resin and enable the formation of a multilayer film with excellent stability and processability.

[0045] In the agricultural polyolefin multilayer film of the present invention, the content of the inorganic fine particles (i) to (ii) above is preferably 0.1 to 2.0 parts by mass, more preferably 0.15 to 1.5 parts by mass, per 100 parts by mass of the resin component in the layer containing the inorganic fine particles. Within the above range, it is possible to provide an agricultural film that has transparency and has both heat-shielding and heat-retaining properties.

[0046] The inorganic fine particle dispersion containing inorganic fine particles can be contained in any of the outer layer, intermediate layer, and inner layer, but it is preferably contained mainly in the intermediate layer in order to avoid denaturation due to the influence of moisture, ultraviolet rays, heat, etc. in the inner and outer layers of the greenhouse.

[0047] As the inorganic fine particles, in addition to the inorganic fine particles (i) and (ii) above, other inorganic fine particles such as silica particles, zeolite, and titanium oxide-containing particles can be added. Here, the titanium oxide-containing particles include, as explained in (ii) inorganic particles, particles consisting of titanium oxide alone (titanium oxide particles) and inorganic particles coated with titanium oxide, for example, mica particles coated with titanium oxide (titanium oxide-coated mica). That is, in the agricultural polyolefin-based multilayer film of the present invention, in addition to (i) the inorganic particle dispersion containing CWO particles or (ii) the inorganic particle dispersion containing CWO particles and titanium oxide-containing particles, titanium oxide-containing particles can be contained as other inorganic particles. Here, the other inorganic fine particles may be added to the same layer as the layer to which the inorganic fine particle dispersion is added, or may be added to a different layer.

[0048] The inorganic fine particle dispersion may be directly melt-kneaded into a thermoplastic resin component in a layer containing the dispersion, or may be melt-kneaded at a high concentration with a thermoplastic resin component to produce a high-concentration inorganic fine particle dispersion-containing composition (hereinafter referred to as a "masterbatch"), and the masterbatch may be diluted with the thermoplastic resin to produce a layer containing inorganic fine particles (hereinafter the thermoplastic resin used to dilute the masterbatch is referred to as a "thermoplastic resin for dilution"). When other inorganic fine particles are added, they can be mixed together to prepare a master batch, or each inorganic fine particle can be mixed separately with a thermoplastic resin and then the two can be mixed together to prepare a master batch. The thermoplastic resin used in the production of the masterbatch and the thermoplastic resin for dilution are preferably the same, but different resins can also be used as long as they are compatible. In the case of melt-kneading, a method in which the materials are mixed in a mixer and melt-kneaded in a kneader is preferred. Examples of the mixer include a Henschel mixer, a tumbler, and a ribbon blender. Examples of the kneader include a single-screw extruder, a twin-screw extruder, and a kneader.

[0049] (3) Optical properties of the agricultural polyolefin multilayer film of the present invention The polyolefin-based multilayer film for agricultural use of the present invention has the optical properties meeting the following requirements 2 to 4.

[0050] (Requirement 2) The average transmittance in the wavelength range of 400 to 800 nm is 75% or more. Here, the average transmittance in the wavelength range of 400 to 700 nm is the average value of the total light transmittance. The average transmittance in the wavelength range of 400 to 700 nm is a measure of transparency, and is preferably 80% or more.

[0051] (Requirement 3) The average transmittance in the wavelength range of 800 to 2500 nm is 75% or less. Requirement 3 is the average transmittance in the near-infrared region, and the lower this value, the better the heat-shielding properties. The average transmittance in the wavelength range of 800 to 2500 nm is preferably 70% or less, and more preferably 65% or less.

[0052] (Requirement 4) Far infrared (400~2500cm -1 ) the average transmittance in the wavelength range is 45% or less. Far infrared (400~2500cm -1 ) is a measure of heat retention, and is mainly related to the content of infrared absorbing agents and heat-shielding agents. The lower this value, the better the heat retention. 400~2500cm -1 The average transmittance (%) in the wavelength range of 400 to 2500 cm is usually measured by a Fourier transform infrared spectrophotometer (transmission measurement). -1 The transmittance can be measured in the wave number range (wavelength range of 4 to 25 μm) and the average transmittance in the same wavelength range (average transmittance in the far infrared region (4-25 μm)) can be calculated. 400~2500cm -1 The average transmittance (%) in this wavelength range is preferably 43% or less.

[0053] The agricultural polyolefin multilayer film of the present invention satisfies requirements 2 to 4, and therefore it is possible to provide an agricultural film that has transparency and combines heat-shielding and heat-retaining properties.

[0054] Furthermore, the polyolefin-based multilayer film for agricultural use of the present invention preferably has the following properties in addition to the above requirements 2 to 4. (Requirement 5) Far infrared (400~2500cm -1 ) The blackbody emissivity correction value (%) of the average transmittance in the wavelength range of 35% or less. Far infrared (400~2500cm -1 ) is usually measured by a Fourier transform infrared spectrophotometer (transmission measurement) from 400 to 2500 cm -1The transmittance is measured over a wavenumber range (4 to 25 μm), and the average transmittance over that wavelength range (average transmittance in the far-infrared region (4-25 μm)) is calculated. The blackbody radiation energy at each wavelength at 15°C is then calculated based on Planck's blackbody radiation formula. The transmittance at each wavelength is multiplied by the blackbody radiation energy at the same wavelength at 15°C, and integrated over the wavelength range of 4 to 25 μm. This total is then divided by the total blackbody radiation energy at 15°C over the same wavelength range to calculate the average transmittance (average transmittance in the far-infrared region (4-25 μm) (blackbody emissivity correction)) weighted to the radiation distribution of far-infrared radiation emitted from a material (assuming the ground inside a greenhouse) over the same wavelength range at 15°C. The average transmittance in the far-infrared region of 4 to 25 μm is a value that correlates with the thermal insulation properties of agricultural films used in greenhouses. However, by performing blackbody emissivity correction, it is possible to specify a performance range that is more highly correlated with the thermal insulation properties of agricultural films intended for use in greenhouses in winter. Far infrared (400~2500cm -1 The blackbody emissivity corrected value (%) of the average transmittance in the wavelength range of ) is preferably 32% or less, and more preferably 30% or less.

[0055] Furthermore, the polyolefin-based multilayer film for agricultural use of the present invention preferably has the following properties in addition to the above requirements 2 to 4. (Requirement 6) In a heat barrier property test in accordance with JIS L 1951, the temperature difference between the temperature after 30 minutes and the initial temperature (after 0 minutes) is preferably less than 38°C. Requirement 6 evaluates the heat-shielding properties of multilayer films through a heat-shielding test using artificial sunlight lighting with a wavelength distribution similar to that of natural sunlight; the lower the value, the better the heat-shielding properties. The artificial sunlight light source specified in the JIS is used as the light source, and a heat receiver is placed on the back of the sample without contact. The heat (radiant heat) from the sunlight that passes through the sample is absorbed by the heat receiver, and the temperature of the heat receiver with the sample attached after 30 minutes of irradiation is measured with a thermoviewer. Details are as described in the examples. The temperature difference between the temperature after 30 minutes measured in a heat barrier property test in accordance with JIS L 1951 and the initial temperature (after 0 minutes) is preferably less than 36°C, more preferably 35°C or less.

[0056] (4) Other additives The agricultural polyolefin multilayer film of the present invention may contain, in at least the outer layer or inner layer, a copolymer (1) of ethylene (A) and a cyclic aminovinyl compound (B) represented by the following formula (2). TIFF2025121324000001.tif36154

[0057] In formula (2), R1 and R2 each independently represent a hydrogen atom or a methyl group, and R3 represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and preferably, R1 and R2 each represent a methyl group, and R3 represents a hydrogen atom.

[0058] The agricultural polyolefin multilayer film of the present invention contains preferably 1 to 40 parts by weight, more preferably 2 to 30 parts by weight, and even more preferably 4 to 20 parts by weight (where the total weight of the resin components contained in the outer and inner layers is taken as 100 parts by weight) of a copolymer (1) of ethylene (A) and a cyclic aminovinyl compound (B) represented by formula (2), which can impart good transparency after weathering.

[0059] The vinyl compound (B) represented by formula (2) can be synthesized by known methods, such as those described in JP-B No. 47-8539 and JP-A No. 48-65180.

[0060] Representative examples of the vinyl compound (B) represented by formula (2) include 4-acryloyloxy-2,2,6,6-tetramethylpiperidine, 4-acryloyloxy-1,2,2,6,6-pentamethylpiperidine, 4-acryloyloxy-1-ethyl-2,2,6,6-tetramethylpiperidine, 4-acryloyloxy-1-propyl-2,2,6,6-tetramethylpiperidine, 4-acryloyloxy-1-butyl-2,2,6,6-tetramethylpiperidine, 4-methacryloyloxy-1-methyl-2,2,6,6-tetramethylpiperidine, 4- ... Examples of the methacryloyloxy-2,2,6,6-tetramethylpiperidine include 4-methacryloyloxy-1,2,2,6,6-pentamethylpiperidine, 4-methacryloyloxy-1-ethyl-2,2,6,6-tetramethylpiperidine, 4-methacryloyloxy-1-butyl-2,2,6,6-tetramethylpiperidine, 4-crotonoyloxy-2,2,6,6-tetramethylpiperidine, and 4-crotonoyloxy-1-propyl-2,2,6,6-tetramethylpiperidine.

[0061] A preferred example of the ethylene-cyclic aminovinyl compound copolymer is one in which the ratio of ethylene (A) to the sum of cyclic aminovinyl compound (B) is 0.0005 to 0.85 mol %, more preferably 0.001 to 0.55 mol %. That is, preferred copolymers of this type have high photostability despite a low content of vinyl monomer (cyclic aminovinyl compound (B)) having a hindered amine group in the side chain. A concentration of cyclic aminovinyl compound (B) of 0.0005 mol % sufficiently exhibits photostabilizing effect, while a concentration of cyclic aminovinyl compound (B) exceeding 0.85 mol % tends to be substantially uneconomical.

[0062] Furthermore, the ethylene-cyclic aminovinyl compound copolymer is preferably one in which the proportion of (B) present in isolation, rather than in a continuous sequence of two or more, is 83% or more, preferably 90% or more, of the total amount of (B).

[0063] Usable commercially available ethylene-cyclic aminovinyl copolymers include XJ100H (manufactured by Japan Polyethylene Co., Ltd.).

[0064] The agricultural polyolefin multi-layer film of the present invention may contain the ethylene-cyclic aminovinyl compound copolymer in any of the outer, intermediate and inner layers, but preferably in the outer and inner layers.

[0065] The agricultural polyolefin multilayer film of the present invention can be imparted with good heat retention by adding an infrared absorber, which can be an inorganic compound (inorganic oxide, inorganic hydroxide, hydrotalcite, etc.) containing at least one atom of Mg, Ca, Al, Si, and Li, which is effective as a heat retaining agent. In the polyolefin-based multi-layer film for agricultural use of the present invention, at least the intermediate layer contains a hydrotalcite.

[0066] In particular, when a hydrotalcite infrared absorber represented by the following formula (3) is used, an inexpensive film with good formability can be obtained.

[0067] JPEG2025121324000002.jpg15134

[0068] There are no particular limitations on how the infrared absorber (heat-retaining agent) represented by the above formula (3) can be obtained, and commercially available products can be used, such as DHT4A (manufactured by Kyowa Chemical Industry Co., Ltd.).

[0069] The infrared absorber (heat retaining agent) is an inorganic fine particle having infrared absorbing ability, and these can be used alone or in combination of two or more. There is no particular limitation on the inorganic fine particle that can be used, but inorganic compounds containing at least one atom selected from the components: Si, Al, Mg, and Ca can be used. Examples include magnesium oxide, calcium oxide, aluminum oxide, silicon oxide, lithium hydroxide, magnesium hydroxide, calcium hydroxide, aluminum hydroxide, magnesium carbonate, calcium carbonate, calcium sulfate, magnesium sulfate, aluminum sulfate, lithium phosphate, calcium phosphate, magnesium silicate, calcium silicate, aluminum silicate, calcium aluminate, magnesium aluminate, sodium aluminosilicate, potassium aluminosilicate, calcium aluminosilicate, kaolin, clay, talc, mica, zeolite, hydrotalcite compounds, lithium-aluminum complex hydroxides, aluminum-lithium-magnesium complex carbonate compounds, aluminum-lithium-magnesium complex silicate compounds, magnesium-aluminum-silicon complex hydroxides, magnesium-aluminum-silicon complex sulfate compounds, magnesium-aluminum-silicon complex carbonate compounds, and metal complex hydroxide salts containing multiple anions. These may be dehydrated from which water of crystallization has been removed.

[0070] The inorganic fine particles may be natural or synthetic, and can be used without being limited by their crystal structure, crystal particle size, or the like.

[0071] In addition, the inorganic fine particles may be coated on the surface with a higher fatty acid such as stearic acid, a higher fatty acid metal salt such as an alkali metal salt of oleic acid, an organic sulfonic acid metal salt such as an alkali metal salt of dodecylbenzenesulfonic acid, a higher fatty acid amide, a higher fatty acid ester, or a wax.

[0072] The above metal complex hydroxide salts can be used alone or in combination of two or more kinds. The average particle size is preferably in the range of 0.05 to 15 μm, more preferably 0.1 to 10 μm. If the average particle size of the inorganic fine particles is smaller than the above range, dispersibility in the resin is poor, resulting in the formation of particles (secondary aggregates of inorganic matter), which deteriorates the appearance of the film, and the film also becomes significantly powdery during kneading with the resin, making it difficult to handle. Conversely, if the average particle size of the inorganic fine particles is larger than the above range, transparency is poor and clogging occurs in the extruder breaker screen, reducing productivity.

[0073] Examples of metal species constituting the organic acid salts, basic organic acid salts and overbased organic acid salts of the above metals include Li, Na, K, Ca, Ba, Mg, Sr, Zn, Cd, Sn, Cs, Al and organic Sn. Examples of organic acids include carboxylic acids, organic phosphoric acids and phenols. Examples of the carboxylic acids include acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, neodecanoic acid, 2-ethylhexyl acid, peranthic acid, benzo ... Argonic acid, capric acid, undecanoic acid, lauric acid, tridecanoic acid, myristic acid, palmitic acid, isostearic acid, stearic acid, 12-hydroxystearic acid, behenic acid, montanic acid, elaidic acid, oleic acid, linoleic acid, linolenic acid, thioglycolic acid, mercaptopropionic acid, octylmercaptopropionic acid, benzoic acid, monochlorobenzoic acid, p-tert-butylbenzoic acid, dimethylhydroxybenzoic acid, 3,Monocarboxylic acids such as 5-di-tert-butyl-4-hydroxybenzoic acid, toluic acid, dimethylbenzoic acid, ethylbenzoic acid, cumic acid, n-propylbenzoic acid, acetoxybenzoic acid, salicylic acid, and p-tert-octyl salicylic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, maleic acid, fumaric acid, citraconic acid, metaconic acid, itaconic acid, aconitic acid, thiodipropionic acid, and phthalic acid Examples of the organic phosphoric acids include dicarboxylic acids such as isophthalic acid, terephthalic acid, oxyphthalic acid, and chlorophthalic acid, or their monoesters or monoamide compounds, and di- or triester compounds of tri- or tetracarboxylic acids such as butanetricarboxylic acid, butanetetracarboxylic acid, hemimellitic acid, trimellitic acid, mellophanic acid, and pyromellitic acid. Examples of the organic phosphoric acids include mono- or dioctyl phosphoric acid, mono- or didodecyl phosphoric acid, mono- or dioctyl phosphoric acid, Examples of the phenols include decyl phosphate, mono- or di-(nonylphenyl)phosphate, phosphonic acid nonylphenyl ester, and phosphonic acid stearyl ester. Examples of the phenols include phenol, cresol, xylenol, methylpropylphenol, methyl-tert-octylphenol, ethylphenol, isopropylphenol, tert-butylphenol, n-butylphenol, diisobutylphenol, isoamylphenol, diamylphenol, isohexylphenol, octylphenol, isooctylphenol, 2-ethylhexylphenol, tert-octylphenol, nonylphenol, dinonylphenol, tert-nonylphenol, decylphenol, dodecylphenol, octadecylphenol, cyclohexylphenol, phenylphenol, phenol, cresol, ethylphenol, cyclohexylphenol, nonylphenol, and dodecylphenol.

[0074] The content of the hydrotalcite infrared absorber is preferably more than 0.1 parts by weight and less than 15 parts by weight, more preferably 1 to 12 parts by weight, per 100 parts by weight of the resin in the intermediate layer of the multilayer film. If the content is less than the above range, the effect of improving heat retention is low, and if it exceeds the above range, problems such as reduced transparency arise. Furthermore, the hydrotalcite infrared absorber can also be contained in the outer layer or inner layer of the multilayer film.

[0075] The agricultural polyolefin multilayer film of the present invention can contain a hindered amine light stabilizer. As the hindered amine light stabilizer, a hindered amine light weathering agent that is usually incorporated into agricultural products can be used, and for example, a hindered amine compound having at least two piperidine ring structures in the molecule and a molecular weight of 500 or more (hereinafter also referred to as a "piperidine ring-containing hindered amine compound") can be preferably used.

[0076] Examples of the piperidine ring-containing hindered amine compound include bis(1,2,2,6,6-pentamethyl-4-piperidyl)-2-butyl-2-(3,5-di-tert-butyl-4-hydroxybenzyl)malonate, tetra(2,2,6,6-tetramethyl-4-piperidyl)butanetetracarboxylate, tetra(1,2,2,6,6-pentamethyl-4-piperidyl)butanetetracarboxylate, bis(2,2,6,6 -tetramethyl-4-piperidyl)·di(tridecyl)butanetetracarboxylate, bis(1,2,2,6,6-pentamethyl-4-piperidyl)·di(tridecyl)butanetetracarboxylate, 3,9-bis[1,1-dimethyl-2-{tris(2,2,6,6-tetramethyl-4-piperidyloxycarbonyloxy)butylcarbonyloxy}ethyl]-2,4,8,10-tetraoxaspiro[5.5]undecane , 3,9-bis[1,1-dimethyl-2-{tris(1,2,2,6,6-pentamethyl-4-piperidyloxycarbonyloxy)butylcarbonyloxy}ethyl]-2,4,8,10-tetraoxaspiro[5.5]undecane, 1,5,8,12-tetrakis[4,6-bis{N-(2,2,6,6-tetramethyl-4-piperidyl)butylamino}-1,3,5-triazin-2-yl]-1,5,8,12-tetraaza Examples include dodecane, 1-(2-hydroxyethyl)-2,2,6,6-tetramethyl-4-piperidinol / dimethyl succinate condensate, 2-tert-octylamino-4,6-dichloro-s-triazine / N,N'-bis(2,2,6,6-tetramethyl-4-piperidyl)hexamethylenediamine condensate, and N,N'-bis(2,2,6,6-tetramethyl-4-piperidyl)hexamethylenediamine / dibromoethane condensate.

[0077] In addition, commercially available hindered amine compounds such as TINUVIN 770, TINUVIN 780, TINUVIN 144, TINUVIN 622LD, TINUVIN NOR 371, CHIMASSORB 119FL, and CHIMASSORB 944 (all manufactured by Ciba-Geigy), Sanol LS-765 (manufactured by Sankyo Co., Ltd.), MARK LA-63, MARK LA-68, MARK LA-68, MARK LA-62, MARK LA-67, and MARK LA-68 (manufactured by Sankyo Co., Ltd.) are also usable. Examples of compounds that can be used include LA-57, LA-900, LA-81, NO-Alkyl-1 (manufactured by ADEKA Corporation), UV-3346, UV-3529, UV-3581, UV-3853 (manufactured by Cytec Corporation), Hostavin N20, Hostavin N24, Hostavin N30, Hostavin 845, Hostavin NOW, Sandubois PR-31, Nylostab S-EED (manufactured by Clariant Japan), and UVINUL5050H (manufactured by BASF Japan). These piperidine ring-containing hindered amine compounds can be used alone or in combination.

[0078] The content of the hindered amine compound is 0.001 to 5 parts by weight, preferably 0.01 to 1 part by weight, relative to 100 parts by weight of the resin in each layer of the multilayer film. If the content is less than 0.001% by weight, sufficient effects cannot be obtained, and if the content is more than 5% by weight, not only is no improvement in effects observed, but also adverse effects such as a deterioration in the physical properties of the film are caused.

[0079] The agricultural polyolefin multilayer film of the present invention can achieve good weather resistance by adding an ultraviolet absorber, but even better effects can be obtained when at least one triaryltriazine ultraviolet absorber represented by the following formula (4) is used.

[0080] Usable ultraviolet absorbers that are usually used in agriculture include, for example, 2-hydroxybenzophenones such as 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-octoxybenzophenone, and 5,5'-methylenebis(2-hydroxy-4-methoxybenzophenone); 2-(2'-hydroxy-5'-methylphenyl)benzotriazole; and 2-(2'-hydroxy-3',5'-di-tert-butylphenyl)benzotriazole. 2-(2'-hydroxy-3',5'-di-tert-butylphenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole, 2-(2'-hydroxy-3',5'-dicumylphenyl)benzotriazole, 2,2'-methylenebis(4-tert-octyl-6-benzotriazolyl)phenol, etc. '-Hydroxyphenyl)benzotriazoles; benzoates such as phenyl salicylate, resorcinol monobenzoate, 2,4-di-tert-butylphenyl-3',5'-di-tert-butyl-4'-hydroxybenzoate, 2,4-di-tert-amylphenyl-3',5'-di-tert-butyl-4'-hydroxybenzoate, hexadecyl-3,5-di-tert-butyl-4-hydroxybenzoate; 2-ethyl-2'-ethoxyoxanilide, 2-ethoxy-4'-dodecyloxanilide substituted oxanilides such as oxanilide; cyanoacrylates such as ethyl-α-cyano-β,β-diphenylacrylate and methyl-2-cyano-3-methyl-3-(p-methoxyphenyl)acrylate; triazines such as 2-(4,6-diphenyl-1,3,5-triazin-2-yl)-5-[(hexyl)oxy]phenol and 2-[4,6-bis(2,4-dimethylphenyl)-1,3,5-triazin-2-yl]-5-(octyloxy)phenol. These ultraviolet absorbers can be used singly or in combination of two or more.

[0081] Particularly effective ultraviolet absorbers include triaryltriazine-type ultraviolet absorbers represented by the following formula (4).

[0082] JPEG2025121324000003.jpg95155

[0083] In formula (4), R2 to R6 each independently represent a hydrogen atom or an alkyl group having 1 to 10 carbon atoms. More preferably, R2 is an alkyl group having 6 to 10 carbon atoms, particularly preferably an alkyl group having 6 to 8 carbon atoms, and R3 to R6 are a hydrogen atom or an alkyl group having 1 to 2 carbon atoms, particularly preferably a hydrogen atom or a methyl group.

[0084] In the above formula (4), if the number of carbon atoms in R2 is less than the above range, bleeding out becomes more likely, which is not preferred, and if it exceeds the above range, weather resistance becomes poor, which is not preferred. If the number of carbon atoms in R3 to R6 is less than the above range, bleeding out becomes more likely, which is not preferred, and if it exceeds the above range, weather resistance becomes poor, which is not preferred. In particular, when the ultraviolet absorber in the present invention is an octyl group and R3 to R6 are methyl groups in the above formula (4), or when R2 is a hexyl group and R3 to R6 are hydrogen atoms in the above formula (4), an agricultural film with particularly excellent bleed-out resistance and chemical stability can be obtained.

[0085] There are no particular limitations on how to obtain the triaryltriazine-based ultraviolet absorber represented by the above formula (4), and commercially available products can be used, such as UV1164 (manufactured by Cytec) and TINUVIN1577FF (manufactured by Ciba Specialty Chemicals).

[0086] The content of the triaryltriazine ultraviolet absorber represented by the above formula (4) in the agricultural polyolefin multilayer film of the present invention is less than 5 parts by weight, preferably 0.001 to 3 parts by weight, and more preferably 0.005 to 1 part by weight, per 100 parts by weight of the total weight of the resin components contained in each layer. If the content is less than the above range, the weather resistance improving effect is low, and if it exceeds the above range, problems such as reduced transparency due to bleed-out occur.

[0087] From a cost perspective, when a triaryltriazine-type UV absorber is used in, for example, a multilayer film, it is not necessarily required that it be contained in all layers of the multilayer film; it is sufficient that it be contained in at least one layer. Furthermore, this triaryltriazine-type UV absorber can be used in combination with one or more commonly used UV absorbers. Furthermore, one or more commonly used UV absorbers can be used in layers that do not contain a triaryltriazine-type UV absorber. Of course, the triaryltriazine-type UV absorber may be contained in all layers, but it can also be contained in, for example, an intermediate layer of a greenhouse, and a UV absorber commonly used for agricultural purposes can be contained in other layers. Furthermore, a triaryltriazine-type UV absorber and a UV absorber commonly used for agricultural purposes can also be contained in the same layer. In this case, it is more cost-effective than using a triaryltriazine-type UV absorber in all layers.

[0088] Triaryltriazine-type ultraviolet absorbers are characterized by good bleed-out properties, and when added to multilayer films, the bleed-out properties can be further improved. Examples of methods for adding an ultraviolet absorber with good bleed-out resistance include an agricultural multilayer film in which the ultraviolet absorber content per unit volume in the intermediate layer X is greater than the ultraviolet absorber content per unit volume in the inner layer Y and X is greater than the ultraviolet absorber content per unit volume in the outer layer Z, an agricultural multilayer film in which 80% or more of the ultraviolet absorber content in the entire film is contained in the intermediate layer, and an agricultural multilayer film in which the ultraviolet absorber is added to a layer other than the surface layer of the multilayer film (a layer other than the inner layer and outer layer of the greenhouse: the intermediate layer).

[0089] The agricultural polyolefin multilayer film of the present invention may also contain various additives commonly used in synthetic resins, such as metal organic acid salts, basic organic acid salts and overbased organic acid salts, epoxy compounds, β-diketone compounds, polyhydric alcohols, halogen oxyacid salts, sulfur-, phenol- and phosphite-based antioxidants, heat stabilizers, lubricants, antistatic agents, colorants, antiblocking agents, antifogging agents, and antimisting agents.

[0090] The antifogging agent is not particularly limited, but suitable are polyhydric alcohol partial esters composed of polyhydric alcohols and higher fatty acids, including various known nonionic surfactants, anionic surfactants, cationic surfactants, etc. Specific examples of such antifogging agents include nonionic surfactants, such as sorbitan surfactants such as sorbitan monostearate, sorbitan monomyristate, sorbitan monopalmitate, sorbitan monobehenate, and esters of sorbitan and alkylene glycol condensates with fatty acids; glycerin surfactants such as glycerin monopalmitate, glycerin monostearate, glycerin monolaurate, diglycerin monopalmitate, glycerin dipalmitate, glycerin distearate, diglycerin monopalmitate monostearate, triglycerin monostearate, triglycerin distearate, and alkylene oxide adducts thereof; and polyethylene glycol monostearate, polyethylene glycol monopalmitate, polyethylene glycol alkylphenyl ether, etc. Examples of surfactants include polyethylene glycol surfactants, trimethylolpropane surfactants such as trimethylolpropane monostearate, pentaerythritol surfactants such as pentaerythritol monopalmitate and pentaerythritol monostearate, alkylene oxide adducts of alkylphenols, esters of sorbitan / glycerin condensates and fatty acids, esters of sorbitan / alkylene glycol condensates and fatty acids, diglycerin dioleate sodium lauryl sulfate, sodium dodecylbenzenesulfonate, cetyltrimethylammonium chloride, dodecylamine hydrochloride, lauric acid lauryl amide ethyl phosphate, triethylcetylammonium iodide, oleylaminodiethylamine hydrochloride, dodecylpyridinium salts, and isomers thereof.

[0091] Examples of the antifogging agent include fluorine-based surfactants and silicone-based surfactants. Specific examples of fluorine-based surfactants include surfactants in which H bonded to C in the hydrophobic group of a normal surfactant has been partially or entirely substituted with F, particularly surfactants containing a perfluoroalkyl group or a perfluoroalkenyl group. The above-mentioned various additives can be used alone or in combination of two or more. Examples of fluorine-containing compounds having a perfluoroalkyl group include anionic fluorine-containing surfactants, cationic fluorine-containing surfactants, amphoteric fluorine-containing surfactants, nonionic fluorine-containing surfactants, and fluorine-containing oligomers.

[0092] The amount of the fluorine-containing compound having a perfluoroalkyl group used is preferably 0.001 to 10 parts by weight, more preferably 0.01 to 5 parts by weight, relative to the total weight of the resin components contained in each layer. If the amount of the fluorine-containing compound used is less than 0.001 part by weight, the anti-fog effect is hardly exerted, and even if it exceeds 10 parts by weight, the effect becomes saturated, which is not preferable.

[0093] Furthermore, fillers that can be used to suppress stickiness of the film or to further improve heat retention include, for example, silica, talc, aluminum hydroxide, hydrotalcite, calcium sulfate, calcium silicate, calcium hydroxide, magnesium hydroxide, kaolin clay, mica, alumina, magnesium carbonate, sodium aluminate, conductive zinc oxide, and lithium phosphate. These fillers may be used alone or in combination of two or more.

[0094] Examples of the phenolic antioxidant include 2,6-di-tert-butyl-p-cresol, 2,6-diphenyl-4-octadecyloxyphenol, stearyl (3,5-di-tert-butyl-4-hydroxyphenyl)-propionate, distearyl (3,5-di-tert-butyl-4-hydroxybenzyl)phosphonate, thiodiethylene glycol bis[(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 1,6-hexamethylene ... [(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid amide], 4,4'-thiobis(6-tert-butyl-m-cresol), 2,2'-methylenebis(4-methyl-6-tert-butylphenol), 2,2'-methylenebis(4-ethyl-6-tert-butylphenol), bis[3,3-bis(4-hydroxy-3-tert-butylphenyl)butylic acid]glycol ester, 4,4'-butylidenebis(6-tert-butyl-m-cresol), 2,2'-ethylidenebis(4,6-di-tert-butylphenol), 2,2'-ethylidenebis( 4-sec-butyl-6-tert-butylphenol), 1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane, bis[2-tert-butyl-4-methyl-6-(2-hydroxy-3-tert-butyl-5-methylbenzyl)phenyl]terephthalate, 1,3,5-tris(2,6-dimethyl-3-hydroxy-4-tert-butylbenzyl)isocyanurate, 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)isocyanurate, 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)-2,4,6 -trimethylbenzene, 1,3,5-tris[(3,5-di-tert-butyl-4-hydroxyphenyl)propionyloxyethyl]isocyanurate, tetrakis[methylene-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]methane, 2-tert-butyl-4-methyl-6-(2-acryloyloxy-3-tert-butyl-5-methylbenzyl)phenol, 3,9-bis[1,1-dimethyl-2-{(3-tert-butyl-4-hydroxy-5-methylphenyl)propionyloxy}ethyl]-2,4,8,10-tetraoxaspiro[5.5]undecane, triethylene glycol bis[(3-tert-butyl-4-hydroxy-5-methylphenyl)propionate], n-octadecyl 3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate, tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionyloxymethyl]methane, etc.

[0095] Examples of the sulfur-based antioxidant include dialkyl thiodipropionates such as dilauryl, dimyristyl, and distearyl thiodipropionate, and β-alkyl mercaptopropionates of polyols such as pentaerythritol tetra(β-dodecyl mercaptopropionate).

[0096] Examples of the phosphite antioxidants include trisnonylphenyl phosphite, tris(2,4-di-tert-butylphenyl) phosphite, tris[2-tert-butyl-4-(3-tert-butyl-4-hydroxy-5-methylphenylthio)-5-methylphenyl] phosphite, tridecyl phosphite, octyldiphenyl phosphite, di(decyl)monophenyl phosphite, monodecyldiphenyl phosphite, mono(dinonylphenyl)bis(nonylphenyl) phosphite, and di(tridecyl)pentaerythritol diphosphite. , distearyl pentaerythritol diphosphite, di(nonylphenyl)pentaerythritol diphosphite, bis(2,4-ditert-butylphenyl)pentaerythritol diphosphite, bis(2,6-ditert-butyl-4-methylphenyl)pentaerythritol diphosphite, tetra(tridecyl)isopropylidenediphenol diphosphite, tetra(tridecyl)isopropylidenediphenol diphosphite, tetra(C12-15 mixed alkyl)-4,4'-n-butylidenebis(2-tert-butyl-5-methylphenol) diphosphite, hexa(tridecyl)-1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane triphosphite, tetrakis(2,4-di-tert-butylphenyl)biphenylene diphosphonite, 2,2'-methylenebis(4,6-di-tert-butylphenyl)(octyl)phosphite, tetrakis(2,4-di-t-butylphenyl)4,4'-biphenylene-diphosphonite, 2,2-methylenebis(4,6-di-t-butylphenyl)octylphosphite, and the like.

[0097] Examples of the coloring agent include phthalocyanine blue, phthalocyanine green, Hansa yellow, alizarin lake, titanium oxide, zinc white, ultramarine blue, permanent red, quinacridone, and carbon black.

[0098] Examples of antiblocking agents include diatomaceous earth, synthetic silica, talc, mica, zeolite, etc. These antiblocking agents can be used alone or in combination of two or more, and the amount is usually preferably in the range of 0.01 to 0.5% by weight.

[0099] The agricultural polyolefin multilayer film of the present invention contains a combination of the above-mentioned components and may further contain the following optional components that can be contained in the agricultural polyolefin multilayer film of the present invention, if necessary: Other optional components include stabilizers, impact resistance improvers, crosslinking agents, fillers, foaming agents, antistatic agents, nucleating agents, anti-plateout agents, surface treatment agents, flame retardants, fluorescent agents, antifungal agents, bactericides, metal deactivators, release agents, pigments, and processing aids.

[0100] To blend various additives into the agricultural polyolefin multilayer film of the present invention, the required amounts of each additive may be weighed and mixed using a blender or kneader such as a ribbon blender, Banbury mixer, Henschel mixer, super mixer, single-screw or twin-screw extruder, roll, or other conventionally known blender or mixer. To form the resin composition thus obtained into a film, known methods can be suitably used, such as melt extrusion (including the T-die method and inflation method), calendaring, roll processing, extrusion molding, blow molding, inflation molding, melt casting, pressure molding, paste processing, powder molding, etc.

[0101] The thickness of the agricultural polyolefin multilayer film of the present invention is preferably in the range of 0.01 to 1 mm, more preferably 0.05 to 0.5 mm, and even more preferably 0.05 to 0.2 mm, from the viewpoints of strength and cost. If it is less than this range, there is a problem in terms of strength, and if it exceeds this range, molding is difficult and problems arise in the workability of spreading.

[0102] Furthermore, in the agricultural polyolefin multilayer film of the present invention, a 3- to 5-layer structure allows for easy layer balance. The layer ratio constituting the 3-layer film is preferably in the range of 1 / 0.5 / 1 to 1 / 5 / 1, more preferably 1 / 2 / 1 to 1 / 4 / 1, from the viewpoints of formability, transparency, and strength. The ratio of the outer layer to the inner layer is not particularly limited, but is preferably approximately the same in terms of the curling tendency of the resulting film.

[0103] The agricultural polyolefin multilayer film of the present invention can also have an anti-fog coating film formed in contact with the innermost layer of the film. In this case, if a large amount of anti-fog agent is contained in the film in contact with the anti-fog coating film, the anti-fog agent may be unevenly sprayed onto the film surface, which may cause problems when forming the anti-fog coating film. However, when various additives are previously concentrated and blended into the base resin of each layer as a masterbatch, a small amount of the anti-fog agent can be used as an anti-tack agent during kneading or as a surface modifier when forming the anti-fog coating film, as long as the object of the present invention is not impaired.

[0104] The agricultural polyolefin-based multilayer film of the present invention can also be coated with other coating films. For example, a dust-proof coating film may be formed on the exterior surface of a greenhouse. In this case, the effect of the present invention, which is to improve the coating film adhesion, may also be obtained for the dust-proof coating film.

[0105] Examples of the anti-fog coating film include compositions containing an inorganic colloidal sol such as silica sol and / or alumina sol and a binder resin such as a thermoplastic resin as the main components. Preferably, an anti-fog coating film containing an inorganic colloidal substance and a hydrophilic organic compound as the main components, or an anti-fog coating film containing an inorganic colloidal substance and an acrylic resin as the main components can be used.

[0106] The inorganic colloidal sol used in the present invention is particularly applied to the surface of a hydrophobic polyolefin resin film to impart hydrophilicity to the film surface.The inorganic colloidal sol can be an aqueous sol obtained by dispersing inorganic aqueous colloidal particles such as silica, alumina, water-insoluble lithium silicate, iron hydroxide, tin hydroxide, titanium oxide, barium sulfate, etc. in water or a hydrophilic medium by various methods.Among these, silica sol and alumina sol are preferably used, and these can be used alone or in combination.

[0107] The inorganic colloidal sol is preferably selected to have an average particle size in the range of 5 to 100 nm. Furthermore, within this range, two or more colloidal sols with different average particle sizes may be used in combination. If the average particle size is too large, the coating may become white and devitrified. If the average particle size is too small, the inorganic colloidal sol may lack stability, which is undesirable. The amount of inorganic colloidal sol blended is preferably 0.2 to 5, preferably 0.5 to 4, in terms of solid weight ratio relative to the total solid weight of the binder resin composition. In other words, if the blending amount is too small, sufficient anti-fogging effect may not be achieved. On the other hand, if the blending amount is too large, not only is the anti-fogging effect difficult to improve in proportion to the blending amount, but the coating formed after application may become cloudy, reducing the light transmittance of the film, and the coating may become rough and brittle, which is undesirable.

[0108] Examples of binder resins include acrylic resins, epoxy resins, urethane resins, and polyester resins. However, when the agricultural polyolefin multilayer film of the present invention is used as the base film (hereinafter also referred to as the "base film of the present invention" or "base film"), it is particularly preferable to use acrylic resins and / or urethane resins in view of their compatibility. More preferably, (a) those made of hydrophilic acrylic polymers, (c) those made of hydrophobic acrylic resins, and (e) those made of hydrophobic acrylic resins and polyurethane emulsions, which will be described later, each have their own characteristics and are preferred.

[0109] Examples of acrylic resins include (a) those made of hydrophilic acrylic polymers, (b) those made of block copolymers containing a hydrophobic molecular chain block and a hydrophilic molecular chain block in one molecule, and (c) those made of hydrophobic acrylic resins. In particular, (a) is preferred because it has excellent compatibility with the base film of the present invention in that it provides rapid initial anti-fogging wetting, while (c) is preferred because it has excellent compatibility with the base film of the present invention.

[0110] Examples of the hydrophilic acrylic polymer (a) include copolymers containing a hydroxyl group-containing vinyl monomer component as the main component (preferably 60% to 99.9% by weight, more preferably 65% to 95% by weight) and 0.1 to 30% by weight of an acid group-containing vinyl monomer component, and partially or completely neutralized products thereof. Examples of the hydroxyl group-containing vinyl monomer component include hydroxyalkyl (meth)acrylates, such as hydroxymethyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 2-hydroxypentyl (meth)acrylate, and 6-hydroxyhexyl (meth)acrylate. These may be homopolymers or copolymers containing these hydroxyalkyl (meth)acrylates as the main component and other monomers that are copolymerizable with these.

[0111] Examples of acid group-containing monomers copolymerizable with these hydroxyalkyl (meth)acrylates include carboxylic acids, sulfonic acids, and phosphonic acids, with (meth)acrylic acid, which belongs to the carboxylic acid group, being particularly preferred.

[0112] Other copolymer components include, for example, styrene, vinyl terene, vinyl chloride, vinylidene chloride, vinyl oxide, (meth)acrylic acid esters, N,N-dimethylaminoethyl (meth)acrylamide, and vinylpyridine.

[0113] Examples of anti-fogging coating films that can be used in the present invention and that are primarily composed of inorganic colloidal substances and hydrophilic organic compounds include compounds disclosed in Japanese Patent Publication Nos. 63-45432, 63-45717, 64-2158, and Japanese Patent No. 3094296.

[0114] Examples of the hydrophobic acrylic resin (c) include water-dispersible polymers or copolymers obtained by emulsion polymerization in an aqueous medium under ordinary polymerization conditions, for example, in the presence of an emulsifier, of a monomer consisting of at least 60% by weight of an alkyl ester of acrylic acid or methacrylic acid, or a monomer mixture of an alkyl ester of acrylic acid or methacrylic acid and an alkenylbenzene, and 0 to 40% by weight of a copolymerizable α,β-ethylenically unsaturated monomer.

[0115] Examples of alkyl esters of acrylic acid or methacrylic acid used in the production of hydrophobic acrylic resins include methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, decyl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, 2-ethylhexyl methacrylate, and decyl methacrylate. Generally, alkyl acrylates having an alkyl group with 1 to 20 carbon atoms and / or alkyl methacrylates having an alkyl group with 1 to 20 carbon atoms are used. Examples of alkenylbenzenes include styrene, α-methylstyrene, and vinyltoluene.

[0116] Examples of α,β-ethylenically unsaturated monomers used to obtain hydrophobic acrylic resins include α,β-ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, maleic anhydride, fumaric acid, crotonic acid, and itaconic acid; α,β-ethylenically unsaturated sulfonic acids such as ethylene sulfonic acid; 2-acrylamido-2-methylpropanoic acid; α,β-ethylenically unsaturated phosphonic acids; hydroxyl group-containing vinyl monomers such as hydroxyethyl acrylic acid or methacrylic acid; acrylonitriles; acrylamides; and glycidyl esters of acrylic acid or methacrylic acid. These monomers may be used alone or in combination, preferably in a range of 0 to 40% by weight. Using too much of these monomers can undesirably reduce anti-fogging performance.

[0117] Acrylic resins can be obtained by emulsion polymerization in an aqueous medium in the presence of one or more known emulsifiers, such as anionic surfactants, cationic surfactants, and nonionic surfactants, polymerization using a reactive emulsifier, or polymerization based on the oligosoap theory without the use of an emulsifier. In the case of polymerization in the presence of an emulsifier, it is preferable to use the emulsifier in an amount of 0.1 to 10% by weight based on the total amount of charged monomers, from the viewpoints of adjusting the polymerization rate and the dispersion stability of the synthesized resin.

[0118] Examples of polymerization initiators preferably used in the production of acrylic resins include persulfates such as ammonium persulfate and potassium persulfate, and organic peroxides such as acetyl peroxide and benzoyl peroxide, which can be used in an amount of 0.1 to 10% by weight based on the total amount of charged monomers.

[0119] It is particularly preferable to use a hydrophobic acrylic resin having a glass transition temperature of 35 to 80° C. If the glass transition temperature is too low, the inorganic colloid particles tend to undergo multiple aggregation and assume a non-uniformly dispersed state, whereas if the glass transition temperature is too high, it tends to be difficult to obtain a transparent, uniform coating film.

[0120] The hydrophobic acrylic resin used in the present invention is preferably used as an aqueous emulsion. The aqueous emulsion obtained by polymerizing each monomer in an aqueous medium may be used as it is, or may be diluted by adding a liquid dispersion medium to the aqueous emulsion. Alternatively, the polymer produced by the above-mentioned polymerization may be separated and collected, and redispersed in a liquid dispersion medium to form an aqueous emulsion.

[0121] On the other hand, examples of (d) urethane-based resins include aqueous compositions and emulsions of polyether-, polyester-, and polycarbonate-based anionic polyurethanes, of which polycarbonate-based anionic polyurethane emulsions are preferred in terms of adhesion of the anti-fog coating to the substrate film, water resistance, and scratch resistance, and silanol-group-containing polycarbonate-based anionic polyurethane emulsions are more preferred in terms of further improving the water resistance and scratch resistance of the anti-fog coating, the time required for the anti-fog effect to develop, and the duration of the anti-fog effect. These may be used alone or in combination of two or more.

[0122] A silanol group-containing polycarbonate-based anionic polyurethane emulsion contains a polyurethane resin containing at least one silanol group in the molecule and a strongly basic tertiary amine as a curing catalyst, and specifically refers to an emulsion in which the silanol group-containing polyurethane resin and the strongly basic tertiary amine are dissolved in an aqueous phase, or a colloidal dispersion system in which they are dispersed in the form of fine particles (emulsion).

[0123] Furthermore, an embodiment of the anti-fog coating suitable for use in the present invention is (e) an emulsion obtained by mixing the above-mentioned (c) hydrophobic acrylic resin and (d) aqueous polyurethane composition, which is preferred in terms of compatibility with the substrate film, satisfying both the speed at which anti-fog properties are developed and the durability of anti-fog properties in a good balance, and also in terms of scratch resistance.

[0124] The amount of the aqueous polyurethane composition to be blended is preferably 0.01 or more and 2 or less, more preferably 0.01 or more and 1 or less, in terms of solids weight ratio to the hydrophobic acrylic resin. If the ratio is less than 0.01, improvement in scratch resistance is unlikely to be observed, and it takes a long time for anti-fogging properties to appear, making it difficult to achieve a sufficient anti-fogging effect. If the amount is too high, not only is it difficult to improve scratch resistance in proportion to the blending amount, but the coating film formed after application tends to become cloudy, reducing light transmittance, and is also disadvantageous in terms of cost, making it undesirable.

[0125] In the present invention, when preparing the antifogging agent composition for forming the antifogging coating, a surfactant such as an anionic surfactant, a cationic surfactant, a nonionic surfactant, or a polymeric surfactant can be added.

[0126] Examples of anionic surfactants include fatty acid salts such as sodium oleate and potassium oleate; higher alcohol sulfates such as sodium lauryl sulfate and ammonium lauryl sulfate; alkylbenzenesulfonates and alkylnaphthalenesulfonates such as sodium dodecylbenzenesulfonate and sodium alkylnaphthalenesulfonate; naphthalenesulfonate-formaldehyde condensates; dialkyl sulfosuccinates; dialkyl phosphate salts; and polyoxyethylene sulfate salts such as sodium polyoxyethylene alkyl ether sulfate and sodium polyoxyethylene alkylphenyl ether sulfate.

[0127] Examples of cationic surfactants include ethanolamines; amine salts such as laurylamine acetate, triethanolamine monostearate formate, and stearamidoethyl diethylamine acetate; and quaternary ammonium salts such as lauryltrimethylammonium chloride, stearyltrimethylammonium chloride, dilauryldimethylammonium chloride, distearyldimethylammonium chloride, and lauryldimethylbenzylammonium chloride.

[0128] Examples of nonionic surfactants include polyoxyethylene higher alcohol ethers such as polyoxyethylene lauryl alcohol, polyoxyethylene lauryl ether, and polyoxyethylene oleyl ether; polyoxyethylene alkylaryl ethers such as polyoxyethylene octylphenol and polyoxyethylene nonylphenol; polyoxyethylene acyl esters such as polyethylene glycol monostearate; polypropylene glycol ethylene oxide adducts; sorbitan fatty acid esters such as sorbitan monostearate, sorbitan monopalmitate, and sorbitan monobenzoate; diglycerin fatty acid esters such as diglycerin monopalmitate and diglycerin monostearate; glycerin fatty acid esters such as glycerin monostearate; pentaerythritol, pentyl acrylate ... Examples include pentaerythritol fatty acid esters such as erythritol monostearate; dipentaerythritol fatty acid esters such as dipentaerythritol monopalmitate; sorbitan and diglycerin fatty acid dibasic acid esters such as sorbitan monopalmitate half adipate and diglycerin monostearate half glutamate; or condensates of these with alkylene oxides such as ethylene oxide and propylene oxide, for example, polyoxyethylene sorbitan monolaurate and polyoxypropylene sorbitan monostearate; polyoxyethylene alkylamine fatty acid amides such as polyoxyethylene stearylamine, polyoxyethylene oleylamine, and polyoxyethylene stearic acid amide; and sugar esters.

[0129] Examples of polymer surfactants include polyacrylates, polymethacrylates, and cellulose ethers.

[0130] The addition of these surfactants allows for easy, rapid, and uniform dispersion of the binder resin and inorganic colloidal sol, and when used in combination with the inorganic colloidal sol, they also impart hydrophilic properties to the surface of a hydrophobic thermoplastic resin film. The amount of surfactant added is preferably selected from the range of 0.1 to 50 parts by weight per 100 parts by weight of the resin solids. If the amount of surfactant added is too small, it takes time for the resin and inorganic colloidal sol to disperse sufficiently, and the anti-fogging effect of the combined use with the inorganic colloidal sol cannot be fully achieved. On the other hand, if the amount of surfactant added is too large, the transparency of the coating formed after application decreases due to bleed-out onto the coating surface, and in severe cases, this can lead to a deterioration in the coating's blocking resistance and water resistance.

[0131] In the present invention, a crosslinking agent can be added when preparing an antifogging agent composition for forming an antifogging coating. The crosslinking agent is effective in crosslinking acrylic resins, in particular, to improve the water resistance of the coating. Examples of crosslinking agents include phenolic resins, amino resins, amine compounds, aziridine compounds, azo compounds, isocyanate compounds, epoxy compounds, and silane compounds, with amine compounds, aziridine compounds, and epoxy compounds being particularly preferred.

[0132] Examples of amine compounds that can be used include aliphatic polyamines such as diethylenetriamine, triethylenepentamine, and hexamethylenediamine; alicyclic amines such as 3,3'-dimethyl-4,4'-diaminocyclohexylmethane and isophoronediamine; and aromatic amines such as 4-4'-diaminodiphenylmethane and m-phenylenediamine. Examples of aziridine compounds that can be used include tris-2,4,6-(1-aziridinyl)-1,3,5-triazine, trimethylolpropane-tri-β-aziridinylpropionate, tris[1-(2-methyl)-aziridinyl]phosphine oxide, and hexa[1-(2-methyl)-aziridinyl]triphosphatriazine.

[0133] Examples of epoxy compounds include reaction products of bisphenol A or bisphenol F with epichlorohydrin, epoxidized novolak resins produced by reacting epichlorohydrin with a resinous reaction product of phenol (or a substituted phenol) with formaldehyde, resinous reaction products produced from epichlorohydrin and an aliphatic polyhydric alcohol such as glycerol, 1,4-butanediol, poly(oxypropylene) glycol, or a similar polyhydric alcohol component, and resins obtained by epoxidation using peracetic acid. Epoxy compounds can also be used in combination with tertiary amines or quaternary ammonium salts as catalysts. These crosslinkers can be used in amounts ranging from 0.1 to 30% by weight based on the acrylic resin solids.

[0134] The antifogging agent composition used in the present invention can contain a liquid dispersion medium as needed. Such liquid dispersion mediums include hydrophilic or water-miscible solvents, including water, such as water; monohydric alcohols such as methyl alcohol, ethyl alcohol, and isopropyl alcohol; polyhydric alcohols such as ethylene glycol, diethylene glycol, and glycerin; cyclic alcohols such as benzyl alcohol; cellosolve acetates; and ketones. These liquid dispersion mediums may be used alone or in combination.

[0135] The antifogging agent composition prepared in the present invention may further contain, if necessary, conventional additives such as antifoaming agents, plasticizers, film-forming aids, viscosity improvers, pigments, pigment dispersants, etc. Furthermore, as a binder component other than the acrylic resin, for example, a water-dispersible urethane resin of a polyether type, a polycarbonate type, or a polyester type may be mixed.

[0136] To form an anti-fog coating on the surface of a substrate film, a solution or dispersion of the anti-fog composition is generally applied by a known coating method such as doctor blade coating, roll coating, dip coating, spray coating, rod coating, bar coating, knife coating, or brush coating, followed by drying. The drying method after application may be either natural drying or forced drying. When forced drying is used, drying is typically performed at a temperature in the range of 50 to 250°C, preferably 70 to 200°C. For heat drying, any suitable method such as hot air drying, infrared drying, far-infrared drying, or ultraviolet curing may be used, with hot air drying being advantageous in terms of drying speed and stability.

[0137] In the present invention, the thickness of the coating formed on the surface of the substrate film is preferably selected to be 1 / 10 or less of the substrate film, but is not necessarily limited to this range. If the thickness of the coating is greater than 1 / 10 of the substrate film, there will be a difference in flexibility between the substrate film and the coating, which is undesirable as it will easily cause phenomena such as the coating peeling off from the substrate film and will also cause cracks in the coating, reducing the strength of the substrate film.

[0138] Furthermore, if the adhesion between the substrate film and the coating derived from the coating composition is insufficient, the substrate film may be subjected to a surface treatment. Examples of treatment methods for the surface of the laminate film of the present invention include corona discharge treatment, sputter etching treatment, sodium treatment, sandblasting treatment, etc. Corona discharge treatment involves generating a discharge between a needle-shaped or knife-edge electrode and a counter electrode, placing a sample between the electrodes, and treating the sample to generate oxygen-containing functional groups such as aldehydes, acids, alcohol peroxides, ketones, and ethers on the film surface. Sputter etching involves placing a sample between electrodes performing a low-pressure glow discharge, and forming numerous fine protrusions on the film by the impact of positive ions generated by the glow discharge. Sandblasting involves spraying fine sand onto the film surface to form numerous fine irregularities on the surface. Among these surface treatments, corona discharge treatment is preferred in terms of adhesion to the coating layer, workability, safety, cost, etc.

[0139] When the agricultural polyolefin multi-layer film of the present invention is actually used, it is preferably stretched out so that the side on which the anti-fogging coating is provided faces the inside of a greenhouse or tunnel.

[0140] The agricultural polyolefin multilayer film of the present invention has excellent transparency and, due to the inorganic microparticles with heat-shielding properties, improves the heat-shielding effect inside agricultural greenhouses in the summer, and this effect is well-maintained.It also has excellent heat retention properties, making it extremely useful as a film for outdoor display. [Example]

[0141] The present invention will be described in more detail below based on examples and comparative examples, but the present invention is not limited to the following examples as long as it does not depart from the gist of the invention.

[0142] (1) Manufacturing of laminated film A three-layer inflation molding machine with a three-layer die of 100 mm diameter (Plakoken Co., Ltd.) was used, and two 30 mm diameter extruders (Plakoken Co., Ltd.) for the outer and inner tube layers and one 40 mm diameter extruder (Plakoken Co., Ltd.) for the middle layer were used. The outer and inner layer extruder temperature was 180°C, the middle layer extruder temperature was 170°C, the die temperature was 180-190°C, the blow ratio was 2.0-3.0, the take-up speed was 3-7 m / min, and the thickness was 0.15 mm to obtain a three-layer laminate film composed of the components shown in Table 1. Note that these films were used by cutting open the end of the tube during expansion in the house, so that the outer layer of the tube during film formation became the inner layer (inner surface) of the house when expanded.

[0143] [Composition] Addition amounts are as shown in each table. HP-LDPE: Branched polyethylene (MFR: 0.8g / 10min, density 0.922) produced using a high-pressure radical catalyst. Ube Maruzen Polyethylene "F022NH" Metallocene PE: Ethylene-α-olefin copolymer produced with a metallocene catalyst (MFR: 2.0 g / 10 min, density 0.91307) Kernel "KF270" manufactured by Japan Polychem. EVA1: Vinyl acetate content = 15 wt%. EF1510: manufactured by Asahi Kasei Corporation.

[0144] Synthetic hydrotalcite A: Kyowa Chemical Industry Co., Ltd. "DHT-4A"

[0145] UV absorber A: Triazine type UV absorber: UV-1164 (2-[4,6-bis(2,4-dimethylphenyl)-1,3,5-triazin-2-yl]-5-(octyloxy)phenol) manufactured by Cytec Corporation

[0146] Ethylene-cyclic aminovinyl copolymer: "kokanoxXJ100H" manufactured by Japan Polyethylene Co., Ltd. (MFR = 3 g / 10 min (190 °C, JIS-K6760), density = 0.931 g / cm 3 (JIS-K6760), cyclic aminovinyl compound content = 5.1 wt% (0.7 mol%), proportion of isolated cyclic aminovinyl compounds = 90 mol%, melting point = 111°C)

[0147] Light stabilizer A: "tinuvin NOR371" manufactured by Chiba Specialty Chemicals

[0148] Inorganic fine particles with heat-shielding properties Heat-shielding agent A: TET 1KS 174 NAT (5 wt% masterbatch; manufactured by Toyo Color Co., Ltd.) Heat-shielding agent B: YMDS-874 (Sumitomo Metal Mining Co., Ltd.)

[0149] (2) Film surface treatment The outer surface of the obtained tubular film was subjected to a corona discharge treatment at a discharge voltage of 120 V, a discharge current of 4.7 A, and a line speed of 10 m / min, and the "wetting index" according to JIS-K6768 was measured and confirmed.

[0150] (3) Formation of anti-fogging coating film An antifogging agent composition was obtained by blending colloidal silica, a thermoplastic resin, a crosslinking agent, and a liquid dispersion medium. The anti-fogging agent composition was formulated as follows: Inorganic colloidal sol (colloidal silica) 4.0 Thermoplastic resin (Sunmol SW-131) 3.0 Crosslinker (TAZM) 0.1 Dispersion medium (water / ethanol = 3 / 1) 93 (Note) The amount of inorganic colloidal sol is expressed as the amount of inorganic particles, and the amount of thermoplastic resin is expressed as the amount of polymer solids. Colloidal silica: Snowtex 30 manufactured by Nissan Chemical Co., Ltd., average particle size 15 mμ Sunmall SW-131: Sanyo Chemical Industries acrylic emulsion TAZM: Aziridine compound manufactured by Sogo Pharmaceutical Co., Ltd. The above anti-fog composition was applied to the surface of each film surface-treated in (2) using a #5 bar coater. The coated film was placed in an oven at 80°C for 1 minute to volatilize the liquid dispersion medium and form an anti-fog coating film. The thickness of the coating film on each film obtained was approximately 1 μm.

[0151] (4) Evaluation of laminated film The following tests were carried out using the film obtained above. Note that similar effects can be obtained with other combinations of resins and additives than those used this time, or with film thicknesses different from those used this time, as long as the gist of the test is not changed. The measurement methods for each test are shown below.

[0152] (1) Transparency: The higher the transmittance, the higher the transparency, and was evaluated by the transmittance of 555 nm straight light. The multilayer film obtained by three-layer inflation molding (after forming (coating) an anti-fogging coating on the surface on the inner layer side of the housing) was measured using a spectrophotometer (Shimadzu Corporation, UV-2450 model). (2) Cultivability: This is a characteristic related to photosynthesis, and the higher the transmittance, the more favorable it is for photosynthesis. It was evaluated based on the average transmittance of visible light (average transmittance from 400 to 700 nm). The multilayer film obtained by three-layer inflation molding (after forming (coating) an anti-fogging coating on the surface of the inner layer of the housing) was measured using a UV-Vis-NIR spectrophotometer (Hitachi High-Tech Corporation, UH4150 model: equipped with an integrating sphere unit).

[0153] (3) Heat-shielding property 1: The ability to block heat rays (near-infrared rays) from sunlight. The lower the transmittance, the higher the heat-shielding property. This was evaluated by measuring the average near-infrared transmittance (average transmittance from 800 to 2500 nm (total light transmittance)). The multilayer film obtained by three-layer inflation molding (after forming (coating) an anti-fogging coating on the surface of the inner layer of the housing) was measured using a UV-Vis-NIR spectrophotometer (Hitachi High-Tech Corporation, UH4150 model: equipped with an integrating sphere unit). (4) Heat-shielding property 2: This is the ability to block heat rays from sunlight. The smaller the temperature difference, the higher the heat-shielding property, which is thought to be mainly related to the heat-shielding agent. It was evaluated using the heat-shielding property test in accordance with JIS L 1951. JIS L 1951 compliant heat insulation test The heat-shielding properties of multilayer films obtained by three-layer inflation molding (after forming (coating) an anti-fog coating on the inner surface of the greenhouse) were evaluated in a heat-shielding test using artificial sunlight lighting with a wavelength distribution similar to that of natural sunlight. The artificial sunlight light source specified in the JIS was used as the light source, and a heat receiver was placed on the back of the sample without contact. The heat (radiant heat) from the sunlight that penetrated the sample was absorbed by the heat receiver. 30 minutes after irradiation, the temperature of the heat receiver with the sample attached was measured with a thermoviewer, and the temperature difference between 30 minutes and the initial temperature (0 minutes) for each sample was calculated. In addition to the samples, the temperature rise of a bare heat receiver (blank) was also measured for each test to confirm reproducibility. An overview of the heat-shielding test equipment is shown in Figure 1.

[0154] (5) Heat retention: This refers to the ability to trap heat rays (far infrared rays) from inside the greenhouse. The lower the transmittance, the better the heat retention, and this is thought to be mainly related to the heat-shielding agent and heat-retaining agent (infrared absorbing agent). This was evaluated by measuring the average transmittance of far-infrared rays (4-25 μm) and the average transmittance of far-infrared rays (4-25 μm) (corrected for blackbody emissivity). Far infrared (4-25μm) average transmittance, far infrared (4-25μm) average transmittance (blackbody emissivity correction) The multilayer film obtained by three-layer inflation molding (after forming (coating) an anti-fogging coating on the surface of the inner layer of the housing) was measured using a Fourier transform infrared spectrophotometer (Shimadzu Corporation, IRAffinity-1 model: transmittance measurement) from 400 to 2500 cm -1 The transmittance was measured in the wavenumber range (wavelength range of 4 to 25 μm) and the average transmittance in the same wavelength range (average transmittance in the far infrared region (4-25 μm)) was calculated. Meanwhile, the blackbody radiation energy at 15°C for each wavelength was calculated based on the following Planck's blackbody radiation formula. TIFF2025121324000004.tif2067 The transmittance at each wavelength was multiplied by the blackbody radiation energy at the same wavelength at 15°C, and the value was integrated over the wavelength range of 4 to 25 μm. The total value was then divided by the total blackbody radiation energy at 15°C in the same wavelength range to calculate the average transmittance (average transmittance in the far-infrared region (4-25 μm) (blackbody emissivity correction)) weighted to the radiation distribution of far-infrared rays emitted from a material at 15°C in the same wavelength range (assuming the ground inside a greenhouse). The average transmittance in the far-infrared region of 4 to 25 μm is a value that correlates with the thermal insulation properties of agricultural films used in greenhouses. However, by performing blackbody emissivity correction, it is possible to specify a performance range that is more highly correlated with the thermal insulation properties of agricultural films intended for use in greenhouses in winter.

[0155] [Examples 1 to 3 and Comparative Examples 1 to 8 (substrate film thickness: 150 μm)] Table 1 shows the formulation of the base film for each sample prepared for the highly dispersed CWO particle system (Examples 1 to 3) and the low dispersed CWO particle system (Comparative Examples 4 to 8) for a base film thickness of 150 μm. The type and content of the heat-shielding agent and the evaluation results for each example and comparative example are shown in Tables 2 and 3. Comparative example 2 is PO Cool (Okamoto Corporation), a commercially available agricultural heat-shielding material, and comparative example 3 is Bisanrun Diastar (MKV Advance Corporation), a commercially available agricultural scattering material.

[0156] [Table 1]

[0157] [Table 2]

[0158] [Table 3]

[0159] [Examples 4 to 6 and Comparative Examples 9 to 16 (substrate film thickness: 100 μm)] Table 4 shows the formulation of the base film for each sample prepared using the highly dispersed CWO particle system (Examples 4 to 6) and the low dispersed CWO particle system (Comparative Examples 12 to 16) for a base film thickness of 100 μm. Tables 5 and 6 show the type and content of the heat-shielding agent and the evaluation results for each example and comparative example. Here, the base film was produced using the same materials and under the same conditions as the base films of Examples 1 to 3, except for the materials described below. UV absorber B: Benzophenone-type UV absorber: BASF Chimassorb 81 (2-hydroxy-4-(octyloxy)-benzophenone) Comparative Example 10 is PO Cool (Okamoto Corporation), a commercially available agricultural heat shielding material, and Comparative Example 11 is Bisanrun Easter (MKV Advance Corporation), a commercially available agricultural scattering material.

[0160] [Table 4]

[0161] [Table 5]

[0162] [Table 6]

[0163] As shown in Tables 2-3 and Tables 5-6, the agricultural polyolefin multilayer film of the present invention is a transparent film that combines heat-shielding and heat-retaining properties, and is an agricultural heat-shielding material that can be used all year round, not only for heat-shielding purposes in the summer but also for greenhouse purposes in the winter, and has extremely high industrial applicability.

Claims

1. A polyolefin-based multilayer film for agricultural use has at least an outer layer, an intermediate layer, and an inner layer, and satisfies the following requirements: (Requirement 1) At least one of the outer layer, intermediate layer, and inner layer contains an inorganic fine particle dispersion containing one or more types of inorganic fine particles selected from the following: (i) Cesium-doped tungsten oxide (ii) Cesium-doped tungsten oxide, titanium oxide-containing particles (Requirement 2) The average transmittance in the wavelength range of 400 to 700 nm is 75% or more. (Requirement 3) The average transmittance in the wavelength range of 800 to 2500 nm is 75% or less. (Requirement 4) The average transmittance in the wavelength range of 4 to 25 μm is 45% or less.

2. The agricultural polyolefin-based multilayer film according to claim 1, further satisfying the following requirements: (Requirement 5) The average transmittance in the wavelength range of 4 to 25 μm corrected by the radiation distribution of blackbody radiation at 15° C. is 35% or less.

3. The agricultural polyolefin-based multi-layer film according to claim 1 , wherein the intermediate layer contains the inorganic fine particle dispersion.

4. 2. The agricultural polyolefin multi-layer film according to claim 1, wherein at least the intermediate layer contains a hydrotalcite.

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