JP7265703B2 - Laminated films, greenhouse horticultural films, and woven and knitted fabrics - Google Patents

Description

TECHNICAL FIELD The present invention relates to laminated films, films for greenhouse horticulture, and woven and knitted fabrics.

Cultivation of plants using agricultural greenhouses is widely practiced because it is possible to control an enclosed space to create an optimum environment for growing plants, thereby increasing the yield and quality of plants.
As shown in the following formula (1), plant photosynthesis is a reaction in which light energy is used as a driving source to produce oxygen gas and carbohydrates from carbon dioxide gas absorbed from the air and water absorbed from the ground. is. In order to cultivate plants in large quantities and economically, it is preferable to use sunlight rather than artificial light.
_{6CO2 + 6H2O → 6O2} + _C6H12O6 (1)
In an agricultural greenhouse that uses sunlight, sunlight has a wavelength of 400 to 800 nm (hereinafter sometimes referred to as "visible light") that is used for photosynthesis of plants, and is unnecessary for photosynthesis of plants. , and contains light with a wavelength of 900 to 1000 nm (hereinafter sometimes referred to as "heat rays") that raises the temperature in the agricultural greenhouse. Is required. This is because when the temperature inside the agricultural house rises due to heat rays, it takes time and money to ventilate, dehumidify and cool in order to maintain the temperature suitable for plant growth (hereinafter referred to as "suitable temperature").

Patent Documents 1 to 4 describe that as agricultural films, synthetic resin films such as polyethylene and polyester are laminated with metal vapor deposition layers, metal foils, metal-containing layers, etc., to block heat rays and the like. However, Patent Documents 1 to 3 describe reflecting and blocking sunlight, but do not describe transmitting visible light.
Here, transmission of visible light is one of the important environmental factors in growing plants. In particular, the total light transmittance is said to be an important factor for growing plants. "1% Theory") has been reported.

On the other hand, Patent Document 4 describes that the laminated film has visible light transmission performance and far-infrared reflection performance. The red reflectance (%)” is as high as “81-89%”, but the “visible light transmittance (%)” is as low as “50-65%” (Examples 1-9).

Here, in the cultivation of plants, if the amount of light taken in by visible light differs depending on the part due to the influence of shadows generated by the frame of the agricultural house and the upper leaves and stems of the plants, a sufficient amount of light cannot be obtained. The presence of parts affects the growth rate of plants. In addition, at a site where visible light is taken in more than necessary, the plant may suffer leaf scorch. In Patent Document 5, a highly scattering satin-like agricultural film that prevents leaf scorching due to direct sunlight has been developed. Further, Patent Document 6 describes an agricultural film suitable for use as an outer lining of an agricultural house, which can prevent leaf scorching and moderate temperature changes in the house in a short period of time. However, Patent Documents 5 and 6 do not at least describe blocking heat rays.

Japanese Patent Application Laid-Open No. 2001-009996 Japanese Patent Application Laid-Open No. 2004-176210 JP 2013-252107 A JP 2012-206430 A JP 2011-109991 A JP 2012-070707 A

Written and edited by Epe Fuveling, Akimasa Nakano, "Tomatoes: High Yield Technology and Theory in Holland", 4th edition, Rural Culture Association, February 2015, p. 10-11

A facility with high visible light transmittance, or even higher total light transmittance, and high light diffusibility that suppresses temperature rise in agricultural greenhouses by preventing heat rays from penetrating and contributes to efficient plant growth. There is a demand for the development of horticultural films.
In addition to being used for greenhouse horticulture, for example, as a film for controlling light used for windows, lighting, etc., it has a heat ray reflection function, a high total light transmittance, and a high light diffusion function. Film development is required.
An object of one embodiment of the present invention is to provide a laminated film having high total light transmittance and light diffusibility while having a heat ray reflecting function.
Another object of the present invention is to provide a film for greenhouse horticulture that improves plant growth.

Means for solving the above problems include the following aspects.
<1>
A laminated film having a heat ray reflective layer and a diffusion layer provided on at least one surface of the heat ray reflective layer,
The diffusion layer is made of a resin composition containing particles and a resin, the average particle diameter of the particles is 6.0 μm or more and 20 μm or less, and the content of the particles is more than 1.0% by mass with respect to the resin. is 25% by mass or less, and the ratio of the thickness of the diffusion layer to the average particle diameter of the particles is 0.5 or more;
The laminate film has an average transmittance of 70% or more at a wavelength of 400 nm to 800 nm, and an average transmittance of 20% or less at a wavelength of 900 nm to 1000 nm.
laminated film.
<2>
The laminated film according to <1>, wherein the particles are organic particles.
<3>
The laminated film according to <1> or <2>, wherein the heat ray reflective layer has a multilayer laminated structure in which at least two kinds of resin layers having different refractive indices are alternately laminated.
<4>
A film for greenhouse horticulture comprising the laminated film according to any one of <1> to <3>.
<5>
A woven or knitted fabric obtained by weaving and knitting a strip-shaped tape cut from the laminated film according to any one of <1> to <4>.

ADVANTAGE OF THE INVENTION According to one aspect of the present invention, there is provided a laminated film having high total light transmittance and light diffusibility while having a heat ray reflecting function.
According to another aspect of the present invention, there is provided a greenhouse horticultural film that enhances plant growth.

It is a partial front view showing one embodiment of the laminated film of the present invention. FIG. 4 is a partial front view showing another embodiment of the laminated film of the present invention;

An embodiment that is an example of the present invention will be described below. The present invention is by no means limited to the following embodiments, and can be implemented with appropriate modifications within the scope of the object of the present invention.

In this specification, a numerical range represented by "to" means a range including the numerical values before and after "to" as lower and upper limits.

<Laminated film>
A laminated film of one embodiment of the present invention is a laminated film having a heat ray reflective layer and a diffusion layer provided on at least one surface of the heat ray reflective layer, wherein the diffusion layer contains particles and a resin. The average particle diameter of the particles is 6.0 μm or more and 20 μm or less, the content of the particles is more than 1.0% by mass and 25% by mass or less with respect to the resin, and the particles The ratio of the thickness of the diffusion layer to the average particle diameter is 0.5 or more, and the laminated film has an average transmittance of 70% or more at a wavelength of 400 nm to 800 nm, and an average transmittance of 20% at a wavelength of 900 nm to 1000 nm. It is below.

That is, the laminated film of the present invention has an average transmittance of visible light contained in sunlight of 70% or more, and an average transmittance of heat rays contained in sunlight of 20% or less. Here, visible light means light with a wavelength of 400 to 800 nm, and heat ray means light with a wavelength of 900 to 1000 nm.
The laminated film of the present invention preferably has an average transmittance of 75% or more at a wavelength of 400 nm to 800 nm, preferably 80% or more, from the viewpoint of obtaining high total light transmittance and light diffusion while having a heat ray reflecting function. and the average transmittance at a wavelength of 900 nm to 1000 nm is preferably 15% or less, more preferably 10% or less, and even more preferably 5% or less.

In the present invention, the average transmittance is a value measured using a spectrophotometer (manufactured by Shimadzu Corporation, MPC-3100). , the average transmittance in each wavelength range was calculated. The incident angle of the measurement light was set to 0 degree.

The laminated film of the present invention has an average transmittance of 70% or more at a wavelength of 400 nm to 800 nm, and an average transmittance of 20% or less at a wavelength of 900 nm to 1000 nm.
That is, since the laminated film of the present invention has an average visible light transmittance of 70% or more, for example, when the laminated film of the present invention is applied to a film for greenhouse horticulture, visible light that serves as a driving source for photosynthesis is transmitted. enough to supply the plants. Furthermore, since the laminated film of the present invention has a high total light transmittance, it is considered that the growth of plants can be sufficiently promoted.
In addition, since the average transmittance of heat rays is 20% or less, for example, when the laminated film of the present invention is applied to a film for greenhouse horticulture, heat rays that raise the temperature in an agricultural house can be sufficiently shielded. Furthermore, since the film itself, such as the heat-absorbing film, generates little heat, it is possible to suppress the temperature rise in the agricultural house, and the cost required for dehumidifying and cooling can be reduced.

Here, as a film having a high average transmittance of visible light and a low average transmittance of heat rays,
o A polyester-based multilayer optical film used for an optical interference filter, as described in JP-A-9-506837,
○ A film containing a multilayer polymer film and a transparent conductor, which is attached to the surface of a window glass, as described in Japanese Patent Application Laid-Open No. 11-508380;
o Laminated polyester films used by laminating to glass in laminated glass, as described in WO 2005/040868;
o A biaxially oriented laminated polyester film used in lamination to glass with laminated glass, as described in WO 2013/080987;
○ A biaxially stretched laminated polyester film that is used by laminating on glass with laminated glass, as described in JP-A-2014-228837,
etc. can be suitably used.

[Heat reflective layer]
The films listed above may be used as the heat ray reflective layer used in the present invention. The heat ray reflective layer used in the present invention is not a metal deposition layer, a metal foil, a metal-containing layer, etc. that can reflect not only heat rays but also visible light, such as those commonly used in agricultural greenhouses, but has a refractive index of It preferably has a multi-layer laminate structure in which at least two different resin layers are alternately laminated.
The thickness of the heat ray reflective layer used in the present invention is adjusted according to the application, preferably 20 μm to 150 μm, more preferably 22 μm to 100 μm, even more preferably 25 μm to 80 μm, particularly preferably 40 μm to 60 μm. If the thickness is thin, there is an advantage that it is light and workability is improved.
Next, a multi-layered structure suitable for use as a heat ray reflective layer will be described in detail.

[Multilayer laminated structure]
The multilayer laminate structure used in the present invention is not particularly limited as long as it has the function of transmitting visible light of sunlight and selectively reflecting heat rays. It is preferable that two kinds of resin layers are alternately laminated. Reflection due to alternate lamination of resin layers with different refractive indices can be designed by designing the reflection wavelength by the optical thickness (refractive index x physical thickness) of the resin layers, and the reflectance by the total number of resin layers and the difference in refractive index between the resin layers. It is possible to adjust the selection of the resin, the thickness of the resin layer, and the number of layers so as to obtain the desired reflection characteristics.
In order to appropriately transmit visible light and selectively reflect heat rays with the multilayer laminated structure, the difference in average refractive index in the in-plane direction between the two types of resin layers is preferably at least 0.03. Moreover, the multilayer structure preferably has at least 101, preferably 151 or more, more preferably 201 or more resin layers having an optical thickness of 100 to 400 nm, preferably 150 to 360 nm. The number of resin layers is preferably as large as possible from the viewpoint of optical function, but if the number is too large, the overall thickness tends to be too thick.

As the resin for forming the resin layer of the multi-layered laminated structure, those known per se can be employed, and polyester, polysulfone, polyamide, polyether, polyketone, polyacryl, polycarbonate, polyacetal, polystyrene, polyamideimide, polyarylate, polyolefin, polyfluoropolymer, polyurethane, polyarylsulfone, polyethersulfone, polyarylene sulfur, polyvinyl chloride, polyetherimide, tetrafluoroethylene, polyetherketone, which are not limited to homopolymers, even copolymers good. In addition, since it is easy to increase the refractive index difference between resins, it is preferable that at least one of the resin layers has, as a repeating unit, a condensed aromatic ring such as a naphthalene ring that easily increases the refractive index. can be

Among these, thermoplastic resins having crystallinity are preferable as the resin used for the resin layer having a high refractive index because they are likely to exhibit a high degree of molecular orientation by stretching, and thermoplastic resins having a melting point of 200° C. or higher are particularly preferable. . From such a point of view, as a specific thermoplastic resin, polyester is preferable, and polyethylene terephthalate and polyethylene-2,6-naphthalene dicarboxylate are more preferable, since they have a particularly high refractive index and can be stretched at a high draw ratio. , polyethylene-2,6-naphthalene dicarboxylate having a condensed aromatic ring is preferred.
On the other hand, the resin used for the resin layer with a low refractive index is not particularly limited as long as it can express a sufficient difference in refractive index from the resin layer with a high refractive index and can maintain the necessary adhesion. For example, a resin obtained by copolymerizing a copolymer component capable of lowering the refractive index to the resin used for the resin layer having a high refractive index can also be used. In addition, since it is not necessary to increase the refractive index by stretching or the like, a resin having a melting point sufficiently lower than that of an amorphous resin or a resin having a high refractive index can be used. For example, an amorphous polyester containing an ethylene terephthalate component can be suitably used. As such an amorphous polyester, for example, cyclohexanedimethanol-copolymerized polyethylene terephthalate (that is, "PETG") is preferable. Polylactic acid, acrylic resin, polycarbonate, and polystyrene can also be used as the resin used for the resin layer with a low refractive index.

[Diffusion layer]
In the laminated film of the present invention, a diffusion layer is provided on at least one surface of the heat ray reflective layer. The diffusion layer has a function of diffusing light. Therefore, when the laminated film of the present invention is used as a film for greenhouse horticulture, it can diffuse the light uniformly to the plants in the facility, and the shadows generated by the framework of the agricultural house and the upper leaves and stems of the plants are less likely to occur. Therefore, the growth of plants can be sufficiently promoted.
The diffusion layer may be provided directly on the heat ray reflective layer, or may be provided via another layer such as an adhesive layer. In addition, the thickness of the diffusion layer is not particularly limited as long as it has a high light diffusion function, but from the viewpoint of suppressing material cost and weight increase, it is preferably 100 μm or less, and 50 μm or less. is more preferably 20 μm or less. Also, the lower limit of the thickness of the diffusion layer is not limited, but from the viewpoint of retaining the particles contained in the diffusion layer, the thickness may be 2 μm or more.
Also, the diffusion layer is made of a resin composition containing particles and a resin. The resin composition may contain additives described later in addition to the particles and the resin.

(resin)
The resin composition forming the diffusion layer contains a resin. Specific examples of resins include (meth)acrylic resins, polyester resins, polyolefin resins, urethane resins, and fluorine resins. These resins may be used singly or in combination of two or more selected from among them.
The above resin is the main component in the resin composition (that is, it contains 50% by mass or more), and preferably contains 70% by mass or more, more preferably 90% by mass or more, relative to the entire resin composition. , more preferably 95% by mass or more.

(particle)
The resin composition forming the diffusion layer contains particles. The particles may be inorganic particles, organic particles, or organic-inorganic composite particles as long as they diffuse light. Specifically, for example, particles of silica, acrylic resin, styrene resin, acrylic/styrene copolymer resin, silicone, melamine resin, benzoguanamine resin, and the like can be used.
The particles contained in the resin composition are preferably organic particles, specifically the organic particles exemplified above, more preferably acrylic resins, styrene resins, and acrylic/styrene copolymer resins. Acrylic resin particles are particularly preferred from the viewpoint of heat resistance or solvent resistance.

The particles contained in the diffusion layer have an average particle diameter of 6.0 μm or more and 20 μm or less. By setting the average particle size of the particles to 6.0 μm or more, it is possible to obtain a laminated film having high light diffusing properties, and by setting the average particle size to 20 μm or less, it is possible to suppress the particles from falling off from the diffusion layer and to achieve high visibility. A laminated film having light transmittance can be obtained. The average particle size of the particles is preferably 7.0 μm to 18 μm, more preferably 7.0 μm to 15 μm.
The average particle size of the particles is measured by the method shown in Examples described later.

Also, the ratio of the thickness of the diffusion layer to the average particle diameter of the particles contained in the diffusion layer is 0.5 or more. By setting the thickness ratio to 0.5 or more, it is possible to suppress the particles from falling off from the diffusion layer. In addition, the upper limit of the thickness ratio is not particularly limited, but from the viewpoint of suppressing material costs, it is preferably 3 or less, more preferably 2.5 or less, and 2 or less. It is even more preferable to have
When the average particle diameter of the particles contained in the diffusion layer is larger than the thickness of the diffusion layer (i.e., the above ratio is less than 1), the thickness of the diffusion layer is the thickness measured where no particles are present. is.

The content of the particles in the diffusion layer is more than 1.0% by mass and 25% by mass or less with respect to the resin contained in the diffusion layer. If the content of the particles exceeds 25% by mass, the appearance of the diffusion layer tends to deteriorate and the properties of the resulting product tend to vary. In addition, from the viewpoint of obtaining high total light transmittance and light diffusibility while having a heat ray reflecting function, the content of the particles is preferably 1.2% by mass or more and 22% by mass or less, more preferably 1.2% by mass or more and 22% by mass or less. It is 3 mass % or more and 19 mass % or less.
As the particles, spherical particles are preferably used. Spherical particles preferably have a higher degree of sphericity, and preferably have an aspect ratio of 1.3 or less, particularly preferably 1.1 or less. The particles are preferably colorless and transparent particles. Here, the term "colorless and transparent" means that there is no coloration that substantially lowers the color purity of the three primary colors and that the material has excellent light transmittance.

(Additive)
The resin composition forming the diffusion layer of the present invention may contain additives shown below.
Additives include, for example, dispersants for improving the dispersibility of particles, various fillers for imparting various functions such as mechanical strength, catalysts for promoting the polymerization reaction of resins, and improving film formation quality. Leveling agents, releasable materials for improving releasability (e.g., fluororesin particles such as PTFE, PFA, FEP, etc.), etc. The content of the additive is based on the resin contained in the diffusion layer. It is preferably 10% by mass or less, more preferably 5% by mass or less, and even more preferably 1% by mass or less.

<Method for producing laminated film>
A method for producing a laminated film according to one embodiment of the present invention will be described in detail. In addition, the manufacturing method shown below here is an example, and the present invention is not limited to this. Different aspects can also be obtained by reference to the following.

The laminated film of the present invention has a heat ray reflective layer and a diffusion layer provided on at least one surface of the heat ray reflective layer. Therefore, first, the method for manufacturing the heat ray reflective layer will be described by taking as an example the case where the heat ray reflective layer has a multi-layer structure in which at least two resin layers having different refractive indices are alternately laminated.
The multilayer laminate structure of one embodiment of the present invention is formed by alternately superimposing the polymer constituting the first layer and the polymer constituting the second layer in a molten state using a multilayer feedblock apparatus to obtain, for example, a total of It can be obtained by forming an alternate lamination structure of 99 or more layers and providing protective layers on both sides thereof.
At this time, the multilayer laminated structure (an example of the “heat ray reflective layer”) is referred to as a multilayer laminated structure including the protective layer. The thickness of the protective layer is preferably 2 μm to 50 μm, more preferably 5 μm to 30 μm, still more preferably 10 μm to 20 μm.
In addition, when a plurality of protective layers are provided in the laminated film, such as having protective layers on both sides of the multilayer laminated structure, the thickness of the protective layers indicates the total thickness thereof.

Such a multilayer structure is laminated such that the thickness of each layer of the first layer and the second layer has a desired gradient structure. This can be achieved, for example, by varying the spacing and length of the slits in a multi-layer feedblock device. This makes it possible to widely reflect light with a wavelength of 900 nm to 1000 nm.

After laminating a desired number of layers by the method described above, the laminate is extruded through a die and cooled on a casting drum to obtain a multilayer unstretched film. The multilayer unstretched film has at least The film is preferably stretched in a uniaxial direction (the uniaxial direction is the direction along the film surface). From the viewpoint of improving mechanical properties, it is more preferable to stretch the film biaxially in the machine direction and the transverse direction. The stretching temperature is preferably in the range of the glass transition temperature (Tg) of the polymer of the first layer to (Tg+20)°C. By stretching at a temperature lower than conventional, the orientation properties of the film can be more highly controlled.

The draw ratio is preferably 2.0 to 6.5 times, more preferably 3.0 to 5.5 times, both in the machine direction and in the transverse direction. The larger the draw ratio within this range, the smaller the variation in the refractive index in the plane direction of the individual layers in the first layer and the second layer due to the thinning due to stretching, and the optical interference of the multilayer laminated structure is uniform in the plane direction. It is preferable because the difference in refractive index between the first layer and the second layer in the stretching direction becomes large. As the stretching method, uniaxial stretching in the longitudinal direction or only in the lateral direction, sequential biaxial stretching in which the longitudinal direction and the lateral direction are separately stretched, and simultaneous biaxial stretching in which the longitudinal direction and the lateral direction are stretched at the same time can be applied. can. As the drawing method in the longitudinal direction and the transverse direction, known drawing methods such as heat drawing with a rod-shaped heater, roll heat drawing, and tenter drawing can be used. , tenter stretching is preferred.

Further, after stretching, heat setting is further performed at a temperature of (Tg) to (Tg + 30) ° C., and toe-in (relaxation) in the stretching direction in the range of 1 to 15%. Thermal stability of the obtained multilayer laminated structure. (eg, heat shrinkage) can be highly controlled.

Next, a method for forming a diffusion layer will be described.
The diffusion layer is provided on at least one surface of the heat ray reflective layer, and may be provided directly on the heat ray reflective layer or may be provided via another layer.
Formation of the diffusion layer is not particularly limited, and may be a coating method, a spin coating method, a transfer method, or the like, but is preferably formed by coating.
For example, as a method of coating and forming a diffusion layer on the surface of the heat ray reflective layer, specifically, known coating techniques such as bar coating, roll coating, knife edge coating, gravure coating, and curtain coating can be used. can be done. In addition, the heat ray reflective layer may be subjected to surface treatment (flame treatment, corona treatment, plasma treatment, ultraviolet treatment, etc.) prior to application of the diffusion layer. Moreover, the coating liquid used for coating is a dispersion of the above-described particles and resin, and may be an aqueous dispersion or a dispersion in which an organic solvent is used.
When the diffusion layer is formed by coating, the coating on the heat ray reflective layer (for example, multilayer laminate structure) can be performed at any stage, but is preferably performed after the manufacturing process of the multilayer laminate structure.
Thus, a laminated film of one embodiment of the present invention is obtained.

<Application of laminated film>
The laminated film of the present invention is preferably used in the field of facility horticulture, the field of construction such as window materials, and the field of transportation equipment such as automobiles, airplanes, and trains. However, it is particularly preferable to use it as a film for greenhouse horticulture. can also be used. A specific example of using the film form as it is is to use the laminated film by attaching it to an object (for example, a window material such as glass). Further, as a specific example of processing and using the laminated film, use as a woven or knitted fabric shown below is mentioned as an example.

<Woven or knitted fabric>
One embodiment in which the laminated film of the present invention is used as a woven or knitted fabric will be described in detail.
In the laminated film of the present invention, since the diffusion layer contains particles, the diffusion layer has the effect of imparting lubricity to the laminated film itself. Therefore, it is possible to perform smooth and uniform weaving and knitting by using the thin belt-like tape obtained by cutting the laminated film as the warp or weft, and using the filament yarn or the like as the weft or warp. In the absence of this effect of imparting lubricity, during weaving and knitting, the narrow belt-like tape may block during storage, or may not be smoothly transported in the weaving and knitting machine, making it impossible to perform weaving and knitting smoothly. Inconvenience arises that the knitting cannot be performed uniformly.

(Lubricity imparting layer)
In addition, in order to further increase the lubricity of the laminated film, a lubricity imparting layer having a function of imparting lubricity may be provided separately from the diffusion layer. A lubricity imparting layer can be provided on the surface.

The lubricity-imparting layer is formed by applying a resin layer containing fine particles having an average particle size of 0.05 to 0.5 μm or a lubricant such as wax to the multi-layered structure, or laminating the layers by co-extrusion. can be done.
Examples of the fine particles include polystyrene, polymethyl methacrylate, methyl methacrylate copolymer, cross-linked methyl methacrylate copolymer, polytetrafluoroethylene, polyvinylidene fluoride, polyacrylonitrile, benzoguanamine resin, polystyrene particles whose outer shell is acrylic. Examples include organic fine particles such as core-shell type particles covered with resin, and inorganic fine particles such as silica, alumina, titanium dioxide, kaolin, talc, graphite, calcium carbonate, feldspar, molybdenum disulfide, carbon black and barium sulfate. Among these, organic fine particles are preferred.
If the average particle size of the fine particles is less than 0.05 µm, the slipperiness of the film tends to be insufficient depending on the particle amount.

In the following, the case of coating will be described as an example.
Alkyd resins, unsaturated polyester resins, saturated polyester resins, phenolic resins, amino resins, vinyl acetate resins, vinyl chloride-vinyl acetate resins, acrylic resins, acrylic-polyester resins, and the like are examples of binders that fix fine particles. can be done. These resins may be homopolymers, copolymers, or mixtures.
The ratio of the fine particles and the film-forming resin (binder) is preferably determined by the design of the coating surface properties. It is preferable that the resin (binder) is 60 to 99.9% by mass. If the fine particles are too small, a uniform and predetermined amount of protrusions cannot be imparted to the coating, whereas if the fine particles are too large, the dispersibility deteriorates, making it difficult to impart a uniform and prescribed amount of protrusions. Too little film-forming resin in the binder will reduce the adhesion of the coating to the polyester film, while too much will reduce blocking resistance.

As a method for providing a lubricity-imparting layer on the laminated film of the present invention, a coating liquid containing fine particles and a film-forming resin, preferably an aqueous coating liquid, is applied to a uniaxially oriented or biaxially oriented multi-layer laminated structure.・A method such as drying and solidifying can be adopted.

Any known coating method can be applied as the coating method. For example, a roll coating method, a gravure coating method, a roll brushing method, a spray coating method, an air knife coating method, an impregnation method, a curtain coating method and the like may be applied singly or in combination. Also, for co-extrusion, a method known per se can be employed.

The woven or knitted fabric of the present invention is a narrow belt-like tape obtained by cutting a raw film (an example of the “laminated film” of the present disclosure) having a diffusion layer on at least one side, preferably both surfaces, of a heat reflective layer, and warp or weft. It is woven and knitted using filament yarn or the like as weft yarn or warp yarn.
In this way, compared to the case where the heat ray reflective layer is used as a film alone, a narrow belt-like tape obtained by cutting the original film having the diffusion layer on at least one surface of the heat ray reflective layer is used as a woven or knitted fabric as warp or weft. As a result, mechanical strength such as windability, blocking resistance, tear resistance and durability of the laminated film can be improved.
Furthermore, since the laminated film of the present invention can be processed into a woven or knitted fabric, the resulting woven or knitted fabric can ensure breathability due to the openings formed between the thin belt-like tapes, filament yarns, or the like. As described above, the woven or knitted fabric of the present invention has excellent air permeability compared to the case where the laminated film is used alone, so that the temperature difference between the cultivation section and the ceiling section is large at night, especially in the morning. As a result, it is possible to prevent the fruits, leaves, flowers, etc. of the plants from discoloring or deteriorating due to the formation of dew condensation on the lower surface of the film, which forms water droplets and hits the plants.

In addition, since the woven or knitted fabric has openings, it is possible to avoid excessive blocking of ultraviolet rays. Avoiding excessive UV shielding may be effective, for example, in improving the coloring of fruits such as eggplants during their growth and in supporting normal pollination activities performed by bees in agricultural greenhouses.

(Aspect of opening)
When a woven or knitted fabric is produced from the laminated film of the present invention, in this woven or knitted fabric, the thickness of the filament yarn or the like is set to 0.01 to 0.30 times the width of the narrow belt-like tape, and the distance between the adjacent narrow belt-like tapes is 0.1 to 0.5 times the width of the strip-shaped tape. "Filament yarn or the like" means filament yarn or spun yarn. The filament yarn used in the present invention may be either a monofilament yarn or a multifilament yarn, and is not particularly limited.

As shown in FIGS. 1 and 2, one example is a tape (warp) 11 obtained by cutting (slitting) a laminated film into a thin strip and weaving it with a filament yarn (weft) 12. , the thickness A of the filament yarn (weft) 12, the width B of the narrow belt-like tape (warp) 11, the interval C between adjacent filament yarns (weft) 12, and the adjacent narrow belt-like tape ( By setting the distance D between the warp threads 11 to a specific range, the open area ratio of the woven or knitted fabric is set to an appropriate range, and a high total light transmittance and heat ray transmission comparable to those obtained when the laminated film is used alone. The UV transmittance is kept within an appropriate range while ensuring the reflectance. Further, filament threads (warp threads) 13 having a thickness of E are interposed as warp threads between the adjacent strip-shaped tapes (warp threads) 11 in order to weave them firmly.

Specifically, in the woven or knitted fabric, the thickness of the filament yarn (weft) 12 is set to 0.01 to 0.30 times the width of the narrow belt-shaped tape (warp) 11, and the adjacent narrow belt-shaped tape (warp) 11 By setting the interval between 0.1 to 0.5 times the width of the narrow belt-shaped tape (warp) 11, the hole area ratio is set to an appropriate range, and compared to the case where the laminated film is used alone as it is, it is inferior. Ultraviolet transmittance can be kept in an appropriate range while ensuring a high total light transmittance and heat ray reflectance. The interval between adjacent filament yarns (weft yarns) 12 is preferably in the range of 1.0 to 10 mm from the viewpoint of the effects of the present invention.

The width of the strip-shaped tape (warp) 11 is preferably 1 to 10 mm, more preferably 2 to 6 mm, even more preferably 3 to 5 mm. The interval between the strip-shaped tapes (warp) 11, that is, the distance between the edges of adjacent strip-shaped tapes (warp) 11 is preferably 0.2 to 1.0 mm, more preferably 0.4 to 0.8 mm. 0.5 to 0.7 mm is more preferable. The thickness of the filament yarn (weft yarn) 12 is preferably 0.05 to 0.35 mm, more preferably 0.1 to 0.3 mm, even more preferably 0.15 to 0.25 mm. The woven or knitted fabric of the present invention can be obtained by setting the width of the narrow belt-shaped tape of the woven or knitted fabric, the thickness of the filament yarn, etc., the interval between adjacent filament yarns, etc., and the interval between adjacent narrow belt-shaped tapes as described above. By setting the transmittance to an appropriate range, the UV transmittance can be set to an appropriate range while ensuring a high total light transmittance and heat ray reflectance comparable to those obtained when the laminated film is used alone.

A woven or knitted fabric formed from the laminated film preferably has a porosity of 10 to 30%. In addition, the "opening ratio" in the present invention refers to a square portion of 10 cm in length and width on one surface of a woven or knitted fabric (area of 100 cm ² ), when the surface of this portion is observed from the direction perpendicular to the surface. A portion that can be seen without obstruction is defined as an aperture, and the sum (Scm ² ) of the area of the aperture (referred to as the aperture area) is calculated by the formula: [S (cm ² )/100 (cm ² )] × 100. is what I asked for.

In the woven or knitted fabric of the present invention, when the porosity is 10% or more, the woven or knitted fabric can have good air permeability, and the skylight provided in the ceiling can be opened at night when photosynthesis is not performed. When the temperature inside the farmhouse is lowered in preparation for the daytime temperature rise of the next day, the air heated during the daytime in the lower part of the farmhouse can escape to the outside through the woven or knitted fabric. In addition, even when the air above the roof close to the roof is cooled at night, especially in the morning, the dew condensation formed on the lower surface of the woven or knitted fabric becomes water droplets and strikes the plants, causing discoloration and deterioration of the fruits, leaves, flowers, etc. of the plants. It is preferable because it can prevent deterioration of the quality of the woven and knitted fabric itself. Further, when the porosity is 30% or less, it is preferable because high total light transmittance and heat ray reflectance provided by the laminated film can be secured.

(Ultraviolet absorption layer)
Since the film for greenhouse horticulture, such as the woven or knitted fabric of the present invention, is exposed to sunlight during the day, it preferably has an ultraviolet absorption layer in order to prevent deterioration due to ultraviolet rays. The ultraviolet absorbing layer can be provided on one surface side or both surface sides of the heat ray reflecting layer. Specifically, it is preferable that an ultraviolet absorption layer is provided on at least one of the diffusion layers.
Further, the diffusion layer itself may have a function of absorbing ultraviolet rays, and even in this case, the above-mentioned ultraviolet absorption layer can be optionally provided.
In the present invention, from the viewpoint of processing efficiency, it is preferable that the diffusion layer has an ultraviolet absorption ability without providing the above-mentioned ultraviolet absorption layer. In this case, a resin having an ultraviolet absorption ability is used as the resin of the diffusion layer. is preferred.

When a resin used for a laminated film constituting a woven or knitted fabric, for example, a multilayer laminated structure is used for a heat ray reflective layer, and a resin having a condensed aromatic ring such as a naphthalene ring is used as a resin with a high refractive index in this multilayer laminated structure Since the resin layer is susceptible to deterioration due to ultraviolet rays, it is particularly effective to provide an ultraviolet absorbing layer. In addition, since the woven or knitted fabric formed from the laminated film of the present invention is provided with the openings described above, even when such an ultraviolet absorbing layer is provided, the woven or knitted fabric itself can be prevented from deteriorating while transmitting necessary ultraviolet rays. can be suppressed.

The thickness of the ultraviolet absorbing layer is preferably 1 to 10 μm. If the thickness of the ultraviolet absorbing layer is 1 μm or more, deterioration of the resin layer can be sufficiently prevented, and if it is 10 μm or less, deterioration of the resin layer can be sufficiently prevented economically and efficiently. Therefore, it is preferable.

The woven or knitted fabric of the present invention has a high total light transmittance, a high heat ray reflectance, and is formed using a laminated film with high diffusion, so it does not hinder the growth of plants and can be used in an agricultural house. It is an excellent one that can suppress the temperature rise of.

Furthermore, in the woven or knitted fabric of the present invention, the thickness of the filament yarn, etc. of this woven or knitted fabric, the width of the narrow band-shaped tape, the interval between adjacent filament yarns, etc., and the interval between adjacent narrow band-shaped tapes are set to specific ranges, By setting the porosity to an appropriate range, the UV transmittance can be set to an appropriate range while ensuring a high total light transmittance and heat ray reflectance comparable to those obtained when the laminated film is used alone. Excellent.

The embodiments of the present invention will be described below with reference to examples, but the present invention is not limited to the examples shown below. Physical properties and characteristics in the examples were measured or evaluated by the following methods.

(Production of heat ray reflective layer A)
A multi-layer laminate structure, which is an example of the heat ray reflective layer A, was produced by the following method.
Polyethylene-2,6-naphthalate (hereinafter referred to as "PEN") having an intrinsic viscosity (ortho-chlorophenol, 35° C.) of 0.62 dl/g as the polyester for the first layer and for the protective layer; As a polyester, cyclohexanedimethanol-copolymerized polyethylene terephthalate (hereinafter referred to as "PETG") having an intrinsic viscosity of 0.77 dl/g (ortho-chlorophenol, 35°C) was prepared by copolymerizing 30 mol% of cyclohexanedimethanol.
After drying the polyester for the first layer and for the protective layer at 180°C for 5 hours, it was supplied to an extruder, and the PEN of the first layer was melted at 290°C. After the second layer of PETG was dried at 120° C. for 10 hours, it was fed into an extruder and heated to 230° C. to form a molten state.
After that, after branching the first layer of PEN into 137 layers and the second layer of PETG into 138 layers, the first PEN layer and the second PETG layer are alternately laminated, and the first layer and the Laminated structure in which the ratio of the maximum layer thickness to the minimum layer thickness (maximum thickness/minimum thickness) in the second layer continuously changes up to 1.4 times, and protective layers on both sides of the laminated structure It was laminated using a multi-layer feedblock device that allowed it to be laminated, and while still in its laminated state, was guided to a die and cast onto a casting drum. Then, an unstretched multi-layer laminated film having a PEN protective layer as the outermost layer on both sides of the film and a total number of 275 layers in the laminated structure portion was prepared. Regarding the thickness of the protective layer, the supply amount was adjusted so that the thickness after stretching was as shown in Table 1. In addition, the discharge amounts of the resins for the first layer and the second layer were adjusted so that the optical thickness ratios of the first layer and the second layer of the laminated structure excluding the protective layer were equal.
The unstretched film thus obtained was preheated at 120° C. and further stretched 3.5 times in the longitudinal direction by heating with an IR heater at 900° C. from 15 mm above between low-speed and high-speed rolls. Subsequently, it was supplied to a tenter and stretched 4.5 times in the transverse direction at 140°C. The resulting biaxially oriented film was heat set at a temperature of 190° C. for 30 seconds and then toe-in (relaxed) in the transverse direction by 1.5%.
The resulting heat ray reflective layer A had a thickness of 55 μm, of which the total thickness of the protective layers on both sides was 13 μm, and a roll having a width of 2000 mm was obtained.

(Preparation of coating liquid A)
Special acrylic resin (Nippon Shokubai Co., Ltd., "UV-G13", which has ultraviolet absorption ability) and polymer particles with an average particle size of 7.3 μm (Sekisui Plastics Co., Ltd., "Techpolymer MBX- 8", spherical fine particles of crosslinked polymethyl methacrylate, aspect ratio 1.3 or less) and a solvent (toluene) were mixed at the mass ratio shown in Table 1 to obtain a coating liquid A.

(Preparation of coating liquid B)
Instead of polymer particles having an average particle size of 7.3 μm, polymer particles having an average particle size of 12.1 μm (Sekisui Plastics Co., Ltd., “Techpolymer MBX-12”, crosslinked polymethyl methacrylate true A coating liquid B was prepared in the same manner as for the coating liquid A, except that spherical fine particles and an aspect ratio of 1.3 or less were used.

(Preparation of coating liquid C)
Instead of polymer particles having an average particle size of 7.3 μm, polymer particles having an average particle size of 17.7 μm (Sekisui Plastics Co., Ltd., “Techpolymer MBX-20”, crosslinked polymethyl methacrylate true A coating liquid C was prepared in the same manner as the coating liquid A, except that spherical fine particles and an aspect ratio of 1.3 or less were used.

(Preparation of coating liquid D)
Instead of polymer particles having an average particle size of 7.3 μm, polymer particles having an average particle size of 2.4 μm (Nippon Shokubai Co., Ltd., “Eposter MA1002”, acrylic-styrene crosslinked true spherical fine particles, Aspect A coating liquid D was obtained by adjusting in the same manner as the coating liquid A, except that a ratio of 1.3 or less was used.

(Preparation of coating liquid E)
Instead of polymer particles having an average particle size of 7.3 μm, polymer particles having an average particle size of 5.2 μm (Sekisui Plastics Co., Ltd., “Techpolymer MBX-5”, crosslinked polymethyl methacrylate true A coating liquid E was prepared in the same manner as the coating liquid A, except that spherical fine particles and an aspect ratio of 1.3 or less were used.

(Preparation of coating liquid F)
Instead of polymer particles having an average particle size of 7.3 μm, polymer particles having an average particle size of 27.1 μm (Sekisui Plastics Co., Ltd., “Techpolymer MBX-30”, crosslinked polymethyl methacrylate true A coating liquid F was prepared in the same manner as the coating liquid A, except that spherical fine particles and an aspect ratio of 1.3 or less were used.

[Example 1-1]
An appropriate amount of coating solution A was placed on a Meyer bar, and coating solution A was applied to one surface of heat ray reflective layer A (thickness: 65 μm) cut into B4 size from the center of a 2000 mm wide roll. This was placed in an oven and dried at 120° C. for 1 minute to solidify the coating layer and obtain a laminated film.
The thickness of the laminated film obtained was 65 μm (heat ray reflective layer: 55 μm, diffusion layer: 10 μm). Moreover, the laminated film obtained was evaluated by the method shown below.

-Thickness of each layer-
The resulting laminated film was cut into a lengthwise direction of 2 mm and a width direction of 2 cm, fixed in an embedding capsule, and then embedded in an epoxy resin (Epomount manufactured by Refinetech Co., Ltd.). The embedded sample was cut perpendicular to the width direction with a microtome (ULTRACUT UCT manufactured by LEICA) to obtain thin slices with a thickness of 50 nm. Observation and photographing were performed using a transmission electron microscope (Hitachi S-4300) at an acceleration voltage of 100 kV, and the thickness (physical thickness) of each layer constituting the multilayer structure, which is an example of the heat ray reflective layer, was measured from the photograph. Also, the thickness of the heat ray reflective layer and the thickness of the diffusion layer were measured with an optical microscope using the same thin slices. Table 1 shows the results.
The thickness of the protective layer in the heat ray reflective layer can be measured with an optical microscope using a thin film section in the same manner as described above.

-Average particle size-
The average particle size of particles contained in the diffusion layer (also referred to as "filler") is measured by the following method.
First, the cross section of the diffusion layer is cut out parallel to the longitudinal direction by a microtome method, and the cross section is sputtered with an extremely thin metal for imparting conductivity to the particle surface. From the image magnified twice, the area circle equivalent diameter is determined and calculated from the following general formula. Table 1 shows the results.
Formula: average particle diameter = sum of area equivalent circle diameters of measured particles / number of measured particles (at least 100 or more)

-Transmittance measurement-
Using a spectrophotometer (manufactured by Shimadzu Corporation, MPC-3100), the spectral spectrum of the obtained laminated film in the wavelength range of 300 nm to 1200 nm was obtained, and the average transmittance in each wavelength range was obtained. .
The measurement was performed at 25° C. in the air atmosphere, and the incident angle of the measurement light was set at 0°. The transmittance at each wavelength was measured at intervals of 2 nm, and the average value of the transmittances in the wavelength range of 400 to 800 nm was taken as the transmittance at the wavelength of 400 to 800 nm. Similarly, the average value of the transmittance in the wavelength range of 900 to 1000 nm was taken as the transmittance for the wavelength of 900 to 1000 nm. Table 1 shows the results.

<Evaluation of total light transmittance>
The total light transmittance was measured using a haze meter (Nippon Denshoku Industries Co., Ltd., NDH-4000) according to JIS K7361-1.
Based on the total light transmittance of the obtained laminated film of each example, evaluation was made according to the following evaluation criteria. Table 1 shows the results.
A total light transmittance of 86% or more is acceptable, and a total light transmittance of 87% or more is considered excellent.

<Evaluation of haze (light diffusion)>
Haze was measured according to JIS K7361-1 using a haze meter (Nippon Denshoku Industries Co., Ltd., NDH-4000). Moreover, it evaluated according to the following evaluation criteria. Table 1 shows the results.
A haze of 20% or more is acceptable, and a haze of 25% or more is excellent from the viewpoint of light diffusion.

<Evaluation of coating appearance>
A roll (width: 2000 mm) of a multi-layered structure (having the same structure as the “heat ray reflective layer A”) was cut into a size of B4 to obtain a multi-layered structure for evaluation.
Using a Meyer bar so that the thickness shown in Table 1 is obtained, a coating solution prepared with each component having the values shown in Table 1 is applied to this multilayer laminated structure for evaluation, and placed in an oven. , 120° C. for 1 minute to solidify the coating solution. The laminated film thus obtained was visually observed, and the coating appearance was evaluated according to the following criteria. Table 1 shows the results.
It should be noted that those evaluated as B in the following evaluation criteria have practically unacceptable appearance, and it was clear that the variation in properties in various parts of the laminated film was not practically acceptable. It was not possible to measure the total light transmittance and haze of Those that could not be measured are indicated as "impossible" in Table 1.
A: Cloudiness, coating streaks and coating unevenness were not observed at all.
B: Unacceptable cloudy spots were observed.

[Examples 1-2 to 1-6, Comparative Examples 2-1, Comparative Examples 5-1 to 5-2]
A laminated film was produced in the same manner as in Example 1-1 except that each component of the coating liquid A was prepared so as to have the values shown in Table 1, and the evaluation was performed in the same manner as in Example 1-1.

[Examples 2-1 to 2-6, Comparative Examples 6-1 to 6-2]
A laminated film was prepared in the same manner as in Example 1-1 except that Coating Solution B was used instead of Coating Solution A, and each component of Coating Solution B was prepared so as to have the values shown in Table 1. The same evaluation as in Example 1-1 was performed. Table 1 shows the results.

[Examples 3-1 to 3-5, Comparative Examples 7-1 to 7-2]
A laminated film was prepared in the same manner as in Example 1-1 except that Coating Solution C was used instead of Coating Solution A and each component of Coating Solution C was prepared so as to have the values shown in Table 1. The same evaluation as in Example 1-1 was performed. Table 1 shows the results.

[Comparative Example 1-1]
Instead of the laminated film obtained in Example 1-1, a film for greenhouse horticulture (Mitsubishi Chemical Agridream Co., Ltd., "Bisanran ^TM Diastar (registered trademark)") was prepared. Example 1- The same operation as in 1 was performed. Table 1 shows the results.

[Comparative Example 1-2]
The same operation as in Example 1-1 was performed except that a film for greenhouse horticulture (Takiron C.I. Co., Ltd., "Kagenashi 5") was prepared instead of the laminated film obtained in Example 1-1. Table 1 shows the results.

[Comparative Examples 3-1 to 3-4]
A laminated film was prepared in the same manner as in Example 1-1 except that Coating Solution D was used instead of Coating Solution A and each component of Coating Solution D was prepared so as to have the values shown in Table 1. The same evaluation as in Example 1-1 was performed. Table 1 shows the results.

[Comparative Examples 4-1 to 4-5]
A laminated film was prepared in the same manner as in Example 1-1 except that Coating Solution E was used instead of Coating Solution A, and each component of Coating Solution E was prepared so as to have the values shown in Table 1. The same evaluation as in Example 1-1 was performed. Table 1 shows the results.

[Comparative Examples 8-1 to 8-4]
A laminated film was prepared in the same manner as in Example 1-1 except that Coating Solution F was used instead of Coating Solution A, and each component of Coating Solution F was prepared so as to have the values shown in Table 1. The same evaluation as in Example 1-1 was performed. Table 1 shows the results.

As can be seen from Table 1, the laminated films of Examples had high total light transmittance and light diffusing properties while having a heat ray reflecting function, compared to the multilayer laminated structure of Comparative Examples.
In particular, the laminated films obtained in Examples could maintain a high total light transmittance in spite of having a diffusion layer.

<Evaluation of plant growth>
Next, a method for evaluating plant growth will be described.
The laminated film obtained in each example was cut to form a strip-shaped tape, and as shown in FIGS. The yarns (weft) 12 were woven and knitted to form a woven or knitted fabric.
The above woven or knitted fabric was put on the outside of a single-building plastic house covered with a special agricultural polyolefin film (Diastar, Mitsubishi Chemical Agridream), and the growth of plants was evaluated inside the house. Tomatoes are used as plants, 16 strains are planted in an area of 2.8m x 2.8m, and the total weight of tomato fruits harvested from June to September 2018 is measured and harvested per unit area amount was calculated. Evaluation was made according to the following criteria. Table 2 shows the results.
A: The yield was 14-20 kg/m ² .
B: Yield was less than 11-14 kg/m ² .
C: Yield was less than 6-11 kg/m ² .

As can be seen from Table 2, it was found that the use of the laminate film of the example as a film for greenhouse horticulture promoted the growth of tomatoes compared to the use of the comparative example.

According to one embodiment of the present invention, the laminated film of the present invention realizes high total light transmittance and light diffusion while having a heat ray reflecting function. Therefore, in the field of greenhouse horticulture where a high total light transmittance is required, for example, even 1%, when the laminated film of the present invention is used as a film for greenhouse horticulture, it has high total light transmittance and light diffusion while having a heat ray reflection function. , the growth of plants is improved.

Claims (6)

A laminated film having a heat ray reflective layer and a diffusion layer provided on at least one surface of the heat ray reflective layer,
The diffusion layer is made of a resin composition containing particles and a resin, the average particle diameter of the particles is 6.0 μm or more and 20 μm or less, and the content of the particles is more than 1.0% by mass with respect to the resin. is 25% by mass or less, and the ratio of the thickness of the diffusion layer to the average particle diameter of the particles is 0.5 or more;
The laminated film has an average transmittance of 70% or more at a wavelength of 400 nm to 800 nm and an average transmittance of 20% or less at a wavelength of 900 nm to 1000 nm ,
The laminated film, wherein the heat ray reflective layer has a multilayer laminated structure in which at least two kinds of resin layers having different refractive indices are alternately laminated. 2. The laminated film according to claim 1, wherein said particles are organic particles. The laminated film according to claim 1 or 2 , wherein the laminated film has a total light transmittance of 86% or more. The laminated film according to any one of claims 1 to 3, wherein the laminated film has a total light transmittance of 87% or more. A film for greenhouse horticulture comprising the laminated film according to any one of claims 1 to 4 . A woven or knitted fabric obtained by weaving and knitting a strip-shaped tape cut from the laminated film according to any one of claims 1 to 4 .

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