JP2011245857A - Laminated film, and structure for plant cultivation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laminated film having excellent balance between scratch resistance, hydrophilic properties and transparency.SOLUTION: In the laminated film having a layer made of a silica fine particles, a layer made of silica fine particles and a resin, and a layer made of a thermoplastic resin, the layer made of silica fine particles and the resin exists between the layer made of silica fine particles and the layer made of the thermoplastic resin, and the layer made of the silica fine particles is the uppermost surface layer of at least one surface of the laminated film.

Description

  The present invention relates to a laminated film and a structure for plant cultivation.

  Conventionally, transparency, scratch resistance, and antifogging properties are required for films used in agricultural houses and agricultural tunnels. In particular, when the film surface temperature is inferior to the dew point of the environment in which the film is used, fine water droplets adhere to the film surface to cause fogging. When cloudiness occurs, the transparency of the film decreases, so the transmittance of sunlight decreases and the growth of the crop is delayed, or water droplets attached to the surface of the film fall on the crop and cause illness, etc. May lead to problems. Therefore, methods for providing an antifogging film on the film surface to make the film surface hydrophilic have been studied and various attempts have been made.

  For example, Patent Document 1 discloses an agricultural drip-proof film in which a synthetic resin film is provided with an aqueous acrylic modified urethane resin coating layer containing colloidal silica particles on one side.

JP-A-7-298791

  However, the film as described in Patent Document 1 has been required to further improve the scratch resistance and transparency.

  The present invention provides a laminated film excellent in the balance of scratch resistance, hydrophilicity and transparency.

  That is, the present invention is a laminated film having a layer made of silica fine particles, a layer made of silica fine particles and a resin, and a layer made of a thermoplastic resin, wherein the layer made of the silica fine particles and the layer made of the thermoplastic resin A layer composed of the silica fine particles and the resin, and the layer composed of the silica fine particles is an outermost layer on at least one surface of the multilayer film.

  The laminated film of the present invention has an excellent balance of scratch resistance, hydrophilicity and transparency.

Photograph showing result of exposure test (2) Photograph showing result of exposure test (4) Photograph showing the result of the exposure test (3) (front test house) and the result of the exposure test (5) (back test house)

  Hereinafter, embodiments of the present invention will be described in detail. The present invention is a laminated film having a layer made of silica fine particles, a layer made of silica fine particles and a resin, and a layer made of a thermoplastic resin, the layer made of the silica fine particles and the layer made of the thermoplastic resin, A layer composed of the silica fine particles and the resin is present between the layers, and the layer composed of the silica fine particles is an outermost layer on at least one surface of the multilayer film.

  Hereinafter, the layer composed of silica fine particles may be referred to as A layer, the layer composed of silica fine particles and resin as B layer, and the layer composed of thermoplastic resin as C layer. First, the B layer will be described below.

The silica fine particles used for the B layer preferably have an average particle size of 0.5 μm or less. The silica fine particles may be elongated, or string-like silica in which a plurality of silica fine particles are connected in a chain. The silica fine particles are used in the form of a sol in which the silica fine particles are dispersed in a liquid dispersion medium such as water. The silica fine particles used for the B layer preferably have an average particle size of 3 nm or more.
A sol in which silica applicable to the present invention is dispersed in a liquid dispersion medium can be obtained as a commercial product. Specifically, SNOWTEX ST-ZL (average particle size: 70 to 100 nm), SNOWTEX ST-YL (average particle size: 50 to 80 nm), SNOWTEX ST-, which are aqueous silica sols manufactured by Nissan Chemical Industries, Ltd. XL (average particle size: 40 to 60 nm), Snowtex ST-20 (average particle size: 10 to 20 nm), Snowtex XS (average particle size: 4 to 6 nm), Snowtex ST-UP (average particle size: 5) -20 nm, length: 40-100 nm).

  The average particle size of silica fine particles is the particle size observed in images using an optical microscope, laser microscope, scanning electron microscope, transmission electron microscope, atomic force microscope, etc., laser diffraction scattering method, dynamic light scattering The average particle size of the BET method, the Sears method, and the like can be used.

Examples of the resin used for layer B include polyurethane resins, acrylic resins, acrylic modified polyurethane resins, vinyl acetate resins, vinyl chloride resins, vinylidene chloride resins, polyester resins, among others. Polyurethane resins are preferred because they are excellent in scratch resistance.
The resin is usually used as an aqueous emulsion in which the resin is dispersed in water or a mixed solvent of water and an aqueous solvent such as alcohol.

Since the film having good smoothness and excellent transparency is obtained, the silica fine particles contained in the B layer is preferably 70% by weight or less. Further, when the silica fine particles contained in the B layer is 30% by weight or more, a film having more excellent scratch resistance can be obtained.
Therefore, when the total of the silica fine particles and the resin in the B layer is 100% by weight, the content of the silica fine particles in the B layer is 30 to 70% by weight, and the content of the resin is 30 to 70% by weight. Preferably, the content of silica fine particles is 50 to 65% by weight, and the resin content is more preferably 35 to 50% by weight.

The B layer made of silica fine particles and resin can be formed, for example, as shown below. An aqueous emulsion containing a resin, an aqueous silica sol containing fine silica particles, and water as a dispersion medium are mixed and stirred to obtain a coating solution. Next, this coating liquid is applied to a layer (C layer) made of a thermoplastic resin using a known means, and dried to form a B layer.
Specific examples of the application means that can be applied to the practice of the present invention include gravure coating, reverse coating, brush coating, spray coating, kiss coating, die coating, and dipping. Examples of the drying means include hot air drying.

  The thickness of the B layer is preferably 0.3 to 1.5 μm, and more preferably 0.5 to 1.2 μm.

  In order to make it easy to apply | coat this coating liquid to the layer (C layer) which consists of a thermoplastic resin mentioned later, a silicone type surfactant can be contained in the said coating liquid. As the silicone-based surfactant, for example, polyether-modified silicone oil is preferable. The amount of these surfactants is usually in the range of 0.01 to 0.3% by weight when the weight of the coating liquid is 100% by weight.

  A crosslinking agent may be added to the coating solution in order to improve the scratch resistance and water resistance of the B layer formed using the coating solution. Moreover, in order to improve the weather resistance of B layer formed using this coating liquid, you may add a light stabilizer and a ultraviolet absorber to a coating liquid.

  Also, in order to make it easy to apply the coating liquid to the C layer, before applying the coating liquid to the layer made of the thermoplastic resin, the surface of the layer made of the thermoplastic resin is subjected to corona treatment, flame treatment, plasma treatment. Surface treatment such as ozone treatment can be performed.

  The B layer may contain components other than the silica fine particles and the resin. When the total weight of the layer B is 100% by weight, the total amount of the silica fine particles and the resin is usually 95% to 100% by weight, preferably 97% by weight or more, and 98% by weight. % Or more is more preferable.

  Next, the A layer in the present invention will be described.

The A layer is a layer made of silica fine particles. The A layer does not contain a resin. When the total weight of the A layer is 100% by weight, the weight of the silica fine particles contained in the A layer is usually 95% by weight or more and 100% by weight or less, preferably 97% by weight or more, preferably 98% by weight or more. Is more preferably 99% by weight or more, and most preferably 100% by weight. When the total weight of the A layer is 100% by weight, the weight of the silica fine particles contained in the A layer is 100% by weight, which means that the A layer is a layer composed only of silica fine particles.
The silica fine particles used for the A layer preferably have an average particle size of 0.5 μm or less. The silica fine particles may be string-like silica. The silica fine particles are used in the form of a sol in which the silica fine particles are dispersed in a liquid dispersion medium such as water. The silica fine particles used for the A layer preferably have an average particle size of 3 nm or more.

  A sol in which silica applicable to the present invention is dispersed in a liquid dispersion medium can be obtained as a commercial product. Specifically, SNOWTEX ST-ZL (average particle size: 70 to 100 nm), SNOWTEX ST-YL (average particle size: 50 to 80 nm), SNOWTEX ST-, which are aqueous silica sols manufactured by Nissan Chemical Industries, Ltd. XL (average particle size: 40 to 60 nm), Snowtex ST-20 (average particle size: 10 to 20 nm), Snowtex XS (average particle size: 4 to 6 nm), Snowtex ST-UP (average particle size: 5) -20 nm, length: 40-100 nm).

In the case of using spherical silica fine particles, it is preferable to use spherical silica fine particles having a small average particle diameter from the viewpoint of reducing external haze. Specifically, silica having an average particle size of 100 nm or less is preferable, and silica having an average particle size of 80 nm or less is more preferable. The average particle diameter of the spherical silica fine particles is preferably 3 nm or more.
The average particle size of silica fine particles is the particle size observed in images using an optical microscope, laser microscope, scanning electron microscope, transmission electron microscope, atomic force microscope, etc., laser diffraction scattering method, dynamic light scattering The average particle size of the BET method, the Sears method, and the like can be used.

Two or more kinds of silica fine particles constituting the A layer may be used in combination. For example, spherical silica having a large average particle diameter and spherical silica having a small average particle diameter can be used in combination for the purpose of densifying the silica array. Further, if necessary, spherical silica and string silica can be used in combination.
When spherical silica having a large average particle diameter and spherical silica having a small average particle diameter are used, a preferable composition is spherical silica having an average particle diameter of 50 to 100 nm / spherical silica having an average particle diameter of 10 nm or less = 99/1 to 70 / 30 (weight ratio).

The A layer composed of silica fine particles can be formed as follows, for example. An aqueous silica sol containing fine silica particles and water as a dispersion medium are mixed and stirred to obtain a coating liquid. Next, A layer can be formed by apply | coating this coating liquid on a base material using a well-known means, and drying. Here, the base material refers to a C layer, a laminated intermediate (1) in which a B layer is laminated on the C layer, or a laminated intermediate (2) in which an anchor coat layer or the like is laminated on the B layer of the laminated intermediate (1). ). Hereinafter, these may be collectively referred to as a base material.
Specific examples of the application means that can be applied to the practice of the present invention include gravure coating, reverse coating, brush coating, spray coating, kiss coating, die coating, and dipping. Examples of the drying means include hot air drying.

  The thickness of the A layer is preferably 0.3 μm or less, more preferably 0.2 μm or less, from the viewpoint of flex resistance and cracking during film formation. The thickness of the A layer is preferably 0.01 μm or more.

  The thicknesses of the A layer and the B layer can be adjusted by the solid content concentration of the coating liquid used for forming each layer, the wet coating amount, and the like.

In the present invention, the silica fine particles of the A layer are preferably arranged as uniformly as possible in both the planar direction and the thickness direction. A laminated film having an A layer composed of silica fine particles that are uniformly arranged has a low and uniform contact angle on the surface of the A layer, and exhibits a low external haze.
In order to form the A layer composed of uniformly arranged silica fine particles, it is preferable to increase the solid content concentration of the coating liquid used for forming the A layer and reduce the wet coating amount.
wet coating amount is preferably from 3 g / ^{m 2} or less, more preferably 2 g / ^{m 2} or less, 1 g / ^{m 2} or less is more preferred. The wet coating amount is preferably 0.01 g / m ² or more. The solid concentration of the coating liquid is preferably 5% by weight or more, more preferably 10% by weight or more, and further preferably 15% by weight or more. The solid content concentration of the coating liquid is preferably 50% by weight or less.

  In order to make it easy to apply the coating liquid to the substrate, the substrate is subjected to surface treatment such as corona treatment, flame treatment, plasma treatment, and ozone treatment before applying the coating solution to the substrate. be able to.

In the laminated film of the present invention, a layer (B layer) made of silica fine particles and a resin exists between a layer made of silica fine particles (A layer) and a layer made of a thermoplastic resin (C layer), and the silica A layer made of fine particles (A layer) is the outermost layer on at least one surface of the laminated film.
There may be other layers such as an anchor coat layer or an adhesive layer between the A layer and the B layer, but the A layer is preferably laminated directly on the B layer.
The difference between the average particle size of the silica fine particles contained in the B layer and the average particle size of the silica fine particles constituting the A layer is preferably 20 nm or less, and more preferably 10 nm or less. The difference between the average particle diameter of the silica fine particles contained in the B layer and the average particle diameter of the silica fine particles constituting the A layer is preferably 0 nm or more. In addition, when the silica fine particle contained in each layer of A layer and B layer is a mixture of a silica fine particle, the average particle diameter of the silica fine particle which is a main component should just satisfy | fill above-mentioned relationship.

Between the A layer and the C layer, the B layer may be a single layer, or the B layer may be two or more layers. When there are two or more B layers, the composition of these B layers may be the same or different.
There may be other layers such as an anchor coat layer or other adhesive layer between the B layer and the C layer.
Of the surface of the C layer, at least the surface on the side where the B layer is provided is preferably smooth. In the C layer, the external haze on the surface on which the B layer is provided is preferably 7% or less, more preferably 5% or less, and even more preferably 3% or less.
As the constitution of the laminated film of the present invention, A layer / B layer / C layer, A layer / B layer / C layer / B layer / A layer, A layer / B layer / C layer / B layer, A layer / B Layer / C layer / A layer, and the like.

The laminated film as described above has an excellent balance of scratch resistance, hydrophilicity, and transparency. Furthermore, since the surface layer of the laminated film is composed of silica fine particles, the surface layer composed of silica fine particles is difficult to adhere to a urethane-based baking finish tin plate or the like. Therefore, the laminated film of the present invention is suitable as an agricultural film.
In particular, when spherical silica having an average particle size of 50 to 100 nm is used as the silica fine particles of the A layer, the laminated film having the A layer formed using the spherical silica is extremely bonded to the urethane-based baking coated tin plate. Hard to do.

  Next, the layer (C layer) made of a thermoplastic resin will be described.

  Specific examples of the thermoplastic resin forming the layer made of the thermoplastic resin include, for example, olefin resins; chlorine-containing resins such as polyvinyl chloride, vinyl chloride / methyl methacrylate copolymer, and polyvinylidene chloride; polyethylene Examples include polyester resins such as terephthalate and polyethylene naphthalate; acrylic resins such as polymethyl methacrylate; fluorine-containing resins; polyamide resins; The layer made of the thermoplastic resin may be formed of a single type of thermoplastic resin or may be formed of a mixture of two or more types of thermoplastic resins. In the case of producing a layer made of a thermoplastic resin by inflation molding, an olefin resin is preferable.

  The olefin resin is a resin obtained by polymerizing an olefin or an olefin and a monomer other than an olefin, specifically, an olefin homopolymer such as an ethylene homopolymer or a propylene homopolymer; / Α-olefin copolymer, ethylene / vinyl acetate copolymer, ethylene / acrylic acid copolymer, ethylene / methyl methacrylate copolymer, ethylene / vinyl acetate / methyl methacrylate copolymer, ionomer resin, ethylene / A copolymer of ethylene and a monomer different from ethylene, such as a copolymer of ethylene and a polymerizable cyclic monomer such as a norbornene copolymer, containing 50% by weight or more of a structural unit derived from ethylene And a copolymer (provided that the weight of the copolymer is 100% by weight). Of these, polyethylene resins such as ethylene homopolymers, ethylene / α-olefin copolymers, ethylene / vinyl acetate copolymers, and ethylene / methyl methacrylate copolymers are particularly preferred from the viewpoints of processability and cost. .

  The ethylene / α-olefin copolymer is composed of a structural unit derived from ethylene and a structural unit derived from α-olefin. The α-olefin is usually an α-olefin having 3 to 20 carbon atoms, preferably an α-olefin having 4 to 12 carbon atoms. Specific examples of such α-olefins include propylene, 1-butene, 4-methyl-1-pentene, 1-hexene, 1-octene and 1-decene. More preferable examples include 4-methyl-1-pentene and 1-hexene. The α-olefin having 3 to 20 carbon atoms may be a combination of two or more, such as 1-butene and 4-methyl-1-pentene, 1-butene and 1-hexene, 1-butene and 1-butene. Examples include octene, 1-butene and 1-decene. More preferably, a combination of 1-butene and 4-methyl-1-pentene or 1-butene and 1-hexene is used.

  The ethylene / α-olefin copolymer in the present invention is preferably an ethylene / 1-butene copolymer, an ethylene / 4-methyl-1-pentene copolymer, an ethylene / 1-hexene-1 copolymer, an ethylene / Examples thereof include a 1-octene copolymer, an ethylene / 1-butene / 1-hexene copolymer, and an ethylene / 1-butene / 1-octene copolymer.

The method for producing a layer made of a thermoplastic resin is not particularly limited. For example, a method usually used for forming a film made of a thermoplastic resin such as an inflation molding method, a T-die casting molding method, or a calendar molding method. Can be manufactured by.
Among these, an inflation molding method that can efficiently produce a layer made of a wide thermoplastic resin is more preferable.

  The thickness of the layer made of the thermoplastic resin is preferably 0.01 mm or more from the viewpoint of strength, and preferably 0.3 mm or less from the viewpoint of coating workability. The range of 0.03-0.25 mm is more preferable, and 0.05-0.15 mm is particularly preferable.

  The layer made of the thermoplastic resin is not limited to a single layer film, and may be a multilayer film. When the layer made of the thermoplastic resin is a multilayer film, the layer structure is not particularly limited, and for example, 2 types, 2 layers, 2 types, 3 layers, 3 types, 3 layers, 3 types, 4 layers, 4 types, 4 layers, 4 types 5 layers, 5 types 5 layers, etc. can be illustrated.

  The thermoplastic resin may contain various additives such as an antioxidant, a light stabilizer, an ultraviolet absorber, an antifogging agent, an inorganic filler, a wax, an antistatic agent, a lubricant, an antiblocking agent, and a pigment. it can. These additives may be used alone or in combination of two or more. These additives are described, for example, in “Practical Handbook for Additives for Plastics and Rubber” Chemical Industry (1970).

  Examples of the antioxidant include phosphorus-based compounds containing trivalent phosphorus atoms such as so-called hindered phenol compounds such as 2,6-dialkylphenol derivatives and 2-alkylphenol derivatives, phosphite compounds, and phosphonite compounds. An ester compound is mentioned. These antioxidants may be used alone or in combination of two or more. In particular, from the viewpoint of stabilizing the hue, it is preferable to use a hindered phenol compound and a phosphorus ester compound in combination. Further, the amount of the antioxidant contained in the layer made of the thermoplastic resin is preferably 0.01 to 1% by weight in each layer when the weight of each layer corresponding to the layer is 100% by weight, and 0.03%. -0.5 wt% is more preferred.

  Examples of the light stabilizer include a hindered amine compound having a structure described in JP-A-8-73667, and specifically, trade names such as tinuvin 622-LD and chimasorb 944-LD (hereinafter, manufactured by BASF). , Hostabin N30, VP Sanduvor PR-31 (manufactured by Clariant, Inc.), Saiyasorb UV3529, Saiyasorb UV3346 (manufactured by Cytec, Inc.), and the like. Furthermore, a sterically hindered amine ether compound having a structure described in JP-A-11-315067 is mentioned, and specifically, trade name Tinuvin NOR371 (manufactured by BASF) is mentioned. The amount of the light stabilizer contained in the layer made of the thermoplastic resin is preferably 0.01 to 3% by weight in each layer when the weight of each layer forming the layer is 100% by weight, 2 wt% is more preferable, and 0.1 to 1 wt% is particularly preferable.

  Examples of UV absorbers include benzophenone UV absorbers, benzotriazole UV absorbers, benzoate UV absorbers, and cyanoacrylate UV absorbers. These can be used alone or in combination of two or more. You may use together. From the viewpoint of weather resistance imparting effect and suppression of bleeding on the film surface, the amount of the ultraviolet absorber contained in the layer made of the thermoplastic resin is such that each layer forming the layer has a weight of 100% by weight. Is preferably 0.01 to 3% by weight, more preferably 0.03 to 2% by weight.

  The inorganic filler can be used for the purpose of improving various performances such as rigidity, heat retention, agricultural chemical resistance, and combustion characteristics of a layer made of a thermoplastic resin. In particular, by containing an inorganic filler having a high radiation absorption property in a layer made of a thermoplastic resin, the heat retaining property of the layer made of the thermoplastic resin can be improved.

Examples of inorganic fillers include hydrotalcite represented by the chemical formula Mg ₆ Al ₂ (OH) ₁₆ (CO ₃ ) · 4H ₂ O and its related compounds, and composite hydroxides such as lithium aluminum composite hydroxide. Can be mentioned.
Specific examples of hydrotalcite and its related compounds include, for example, natural hydrotalcite, Stabiace-P (manufactured by Sakai Chemical Industry Co., Ltd.), DHT-4A (manufactured by Kyowa Chemical Industry Co., Ltd.), Mag Clear (Toda Kogyo Co., Ltd.) Synthetic hydrotalcite such as the company).
Specific examples of the lithium aluminum composite hydroxide include OPTIMA-SS (manufactured by Toda Kogyo Co., Ltd.), Mizukarak (manufactured by Mizusawa Chemical Co., Ltd.), and the like.

  The content of the inorganic filler in the layer made of the thermoplastic resin is preferably 0.1 to 60% by weight, preferably 1 to 30% by weight when the weight of each layer forming the layer made of the thermoplastic resin is 100% by weight. Is more preferable, and 5 to 20% by weight is particularly preferable. In the case of using an inorganic filler, by using a surfactant in combination, the dispersibility of the inorganic filler is improved, and a layer made of a thermoplastic resin that is more excellent in transparency can be obtained.

  The purpose of use of the antifogging agent is not particularly limited, but it can be used as a surface modifier for a layer made of a thermoplastic resin. When the layer made of the thermoplastic resin is a multilayer film, an antifogging agent can be used for the layer closest to the B layer as long as the object of the present invention is not impaired.

  Although the manufacturing method of the laminated | multilayer film of this invention is not specifically limited, The following methods are mentioned as a preferable aspect. First, a layer made of a cylindrical thermoplastic resin is formed by an inflation molding method. Next, a B layer made of silica fine particles and a resin is formed on the outer surface of the cylindrical thermoplastic resin layer by the above method, and an A layer made of silica fine particles is formed by the above method. This method is efficient because the process from the production of a layer made of a thermoplastic resin to the production of a laminated film can be performed in an in-line manner.

  The laminated film of the present invention is suitable as a member for a structure for plant cultivation. The structure for plant cultivation is a structure composed of a frame and a covering material covering the frame and forming the outer shape of the structure, and is a structure used for cultivating plants therein It is a thing. The laminated film of the present invention is suitable as the covering material. Examples of plant cultivation structures include agricultural houses and agricultural tunnels.

  When the laminated film of the present invention is used as the covering material, the layer A of the laminated film may be the outer surface of the structure or the inner surface of the structure. A laminated film in which both outermost layers are A layers is preferably used.

  A plant cultivation structure comprising a frame and a covering material covering the frame, wherein the coating material is the laminated film of the present invention, and the layer A of the laminated film is the inner surface of the structure The structure is cultivated in the structure because the A layer which is the inner surface of the structure is hydrophilic, and even if water droplets adhere to the A layer, the water droplets flow along the surface of the layer. Water drops do not fall on the plant.

  In areas where there is a lot of snow, snow is piled up on structures for plant cultivation, and the structure has collapsed due to the weight of the accumulated snow. It is expected that the occurrence of such damage can be suppressed by using a covering material that does not easily accumulate snow on the covering material as a covering material for the structure. In the laminated film of the present invention, the outermost layer A is hydrophilic, so that the snow falling on it is slippery from the surface of the laminated film and is difficult to accumulate on the surface of the laminated film. Therefore, a plant cultivation structure composed of a frame and a covering material covering the frame, wherein the covering material is the laminated film of the present invention, and the A layer of the laminated film is the outer surface of the structure The structure for cultivation is less likely to accumulate snow on the surface of the structure and is less likely to collapse.

  In recent years, due to global warming, there has been a problem that the temperature in the structure for plant cultivation becomes too high in summer. A plant cultivation structure comprising a frame and a covering material covering the frame, wherein the coating material is the laminated film of the present invention, and the layer A of the laminated film is the outer surface of the structure By spraying water on the outer surface of the structure, the temperature rise in the structure can be suppressed.

  Moreover, in the structure for plant cultivation, when it is used for a long period of time, there is a problem that the outer surface of the covering material becomes dirty and the daylighting property is lowered. A plant cultivation structure comprising a frame and a covering material covering the frame, wherein the coating material is the laminated film of the present invention, and the layer A of the laminated film is the outer surface of the structure The outer surface of the structure is difficult to get dirty. This is because even if dirt such as dust or ash adheres to the outer surface of the structure, the outer layer A layer is hydrophilic, so that the dirt is washed away by rain. Since the structure hardly adheres to the outer surface of the structure, the structure is preferably used in an area where the outer surface of the structure is easily contaminated, such as an area close to an active volcano.

  When the laminated film in which the layers are laminated in the order of A layer / B layer / C layer is used so that the A layer of the laminated film is the outer surface of the structure, the inner surface of the structure is a layer made of a thermoplastic resin ( C layer). In such a case, it is preferable to use a laminated film in which a layer made of a thermoplastic resin contains an antifogging agent. When a laminated film having a C layer made of a thermoplastic resin and an antifogging agent is used, even if water droplets adhere to the C layer, which is the inner surface of the plant cultivation structure, the water droplets flow along the surface of the layer, Water drops do not fall on the plants cultivated in the structure. As the antifogging agent, known antifogging agents can be used.

  The laminated film of the present invention can be used as a covering material for outdoor tents, electric wires, vehicle structures, and other outdoor use structures in addition to the covering material for plant cultivation structures.

  Examples of the present invention will be described below, but the present invention is not limited thereto. In addition, the test method in an Example and a comparative example is as follows.

(1) Scratch resistance test Using a friction fastness tester RT-200 (manufactured by Daiei Kagaku Seiki Seisakusho Co., Ltd.), the surface of the laminated film (A layer or B layer) with steel wool (# 0000) and a load of 500 gf ) Was rubbed 5 times. The total haze of the laminated film was measured before and after the friction, and haze difference (Δhaze) = (total haze after friction test) − (total haze before friction test) was determined. The smaller the value of Δhaze, the better the scratch resistance. Haze was measured according to JIS K7105 using a direct-reading type haze computer HGM-2DP (manufactured by Suga Test Instruments Co., Ltd .; measuring light C light).

(2) Contact angle An automatic contact angle meter DM-301 (manufactured by Kyowa Interface Science Co., Ltd.) was used, and after a water drop was dropped on the surface of the laminated film, the contact angle after 40 seconds was measured. The measurement was performed at 23 ° C. and 50% RH. For Examples 1 and 2 and Comparative Examples 1 to 4, the measurement was performed after 7 days from the film formation, and for Examples 3 to 6, the measurement was performed after 110 days from the film formation.

(3) Transparency test The external haze on the surface of the laminated film was measured.
The haze was measured in accordance with JIS K7105 using a direct reading haze computer HGM-2DP (manufactured by Suga Test Instruments Co., Ltd .; measuring light C light).
The external haze of the measurement surface (A layer or B layer) of the laminated film is the haze value measured after applying dimethyl phthalate to the non-measurement surface of the laminate film and erasing the scattered light on the non-measurement surface. 1) Haze (1) and haze (2) when haze value (internal haze) measured after applying dimethyl phthalate on both surfaces of the film and erasing scattered light on both surfaces was taken as haze (2) It is a difference.

(4) Layer thickness The cross section of the laminated film was observed with an electron microscope, and the thickness of each layer of the layer made of silica fine particles (A layer) and the layer made of silica fine particles and a resin (B layer) was measured.

(5) Tin-resistant adhesion test method Blue (urethane) baked tin plate (Part No .: APC0.35, CGCCR, F-1041, made by Nippon Steel Pipe Co., Ltd.) surface of laminated film with a width of 20 mm (A layer or B layer) The surface of the laminated film to which water was attached and the tin plate were overlapped and adhered by a hand roller, and dried in an oven at 80 ° C. for 3 hours to prepare a test sample. Using an autograph (Shimadzu AGS100, load cell 5 kg), a speed of 50 mm / min. The test sample was peeled in the 180 ° direction and the strength was measured.

  Next, a method for producing a layer (C layer) made of the thermoplastic resin used in Examples and Comparative Examples will be described.

<Preparation of C layer>
A layer made of a thermoplastic resin having a thickness of 100 μm in which an outer layer, an intermediate layer, and an inner layer were laminated in this order was produced by a coextrusion inflation molding method (processing temperature: 160 ° C.). In addition, the weight ratio of the extrusion amount of the outer layer, the intermediate layer, and the inner layer was set to outer layer / intermediate layer / inner layer = 2/6/2. The composition of each layer is as follows.

The outer layer is made of polyethylene resin (Excellen GMH CB0004, melt flow rate 0.4 g / 10 min, density 926 kg / m ³ ; manufactured by Sumitomo Chemical Co., Ltd.) 79.3 wt%, polyethylene resin (Sumikasen E FV203, melt flow rate 2 0.0 g / 10 min, density 913 kg / m ³ , manufactured by Sumitomo Chemical Co., Ltd.) 20.0% by weight, a thermoplastic as a light stabilizer, 0.6% by weight of a hindered amine compound, and 0.1% by weight of an antioxidant. It formed with the resin composition.

The intermediate layer is made of polyethylene resin (Excellen GMH GH030, melt flow rate 0.5 g / 10 min, density 912 kg / m ³ ; manufactured by Sumitomo Chemical Co., Ltd.) 85.6 wt%, synthetic hydrotalcite 13 wt% as an inorganic filler And a thermoplastic resin composition comprising 0.6% by weight of a glycerin fatty acid ester as an antifogging agent, 0.7% by weight of a hindered amine compound as a light stabilizer, and 0.1% by weight of an antioxidant.

The inner layer was made of polyethylene resin (Excellen GMH GH030, melt flow rate 0.5 g / 10 min, density 912 kg / m ³ ; manufactured by Sumitomo Chemical Co., Ltd.) 41.9 wt%, polyethylene resin (Excellen GMH GH051, melt flow rate 0 .4g / 10 min, a density 921kg / m ^3; manufactured by Sumitomo chemical Co., Ltd.) 37.4 wt% of polyethylene resin (Sumikathene E FV203, melt flow rate 2.0 g / 10 min, a density 913kg / m ^3; Sumitomo chemical stock (Company) 20.0% by weight, a thermoplastic resin composition comprising 0.6% by weight of a hindered amine compound as a light stabilizer and 0.1% by weight of an antioxidant.

  The external haze on the outer layer side surface was 6%.

  Next, a method for producing the coating liquid used in Examples and Comparative Examples will be described.

<Preparation of coating liquid>
The raw materials of the coating liquid used are as follows.
(1) Silica Sol Snowtex ST-YL: Average particle size = 50-80 nm, solid content = 40% by weight
Snowtex ST-XL: average particle size = 40-60 nm, solid content = 40% by weight
(All are manufactured by Nissan Chemical Industries, Ltd. The average particle size is a value according to the BET method.)
(2) Acrylic-modified polyurethane emulsion Adekabon titer HUX-401; solid content concentration = 37% by weight (manufactured by ADEKA Corporation)
(3) Polyether-modified silicone surfactant FZ-77 (manufactured by Dow Corning Toray)

  Said raw material and water were mixed by the predetermined | prescribed compounding ratio, and the coating liquid (a)-(shi) shown in Table 1, 2 was obtained.

  Next, Examples 1 to 2 and Comparative Examples 1 to 4 will be described.

[Example 1]
<Formation of A layer and B layer>
A corona treatment was applied to the outer layer of the thermoplastic resin layer. The coating liquid (a) was applied to the surface of the layer made of the corona-treated thermoplastic resin to form a coating film. For coating, a bar having a wet coating amount of 13 μm was used. Thereafter, the layer made of the thermoplastic resin on which the coating film was formed was dried with hot air at 60 ° C. for 1 minute, and the laminated intermediate in which the layer made of silica fine particles and the resin was laminated on the layer made of the thermoplastic resin Obtained.
Further, a coating liquid (e) was applied on the layer composed of the silica fine particles and the resin to form a coating film. For the coating, a bar having a wet coating amount of 5 μm was used. Thereafter, the laminated intermediate on which the coating film is formed is dried with hot air at 60 ° C. for 1 minute, and consists of a layer made of a thermoplastic resin (C layer), a layer made of silica fine particles and a resin (B layer), and silica fine particles. A laminated film in which layers (A layer) were sequentially laminated was obtained. Table 3 shows the configurations of the A layer and the B layer, and Table 4 shows the test results of the laminated film.

[Example 2]
<Formation of A layer and B layer>
A corona treatment was applied to the outer layer of the thermoplastic resin layer. The coating liquid (I) was applied to the surface of the layer made of the corona-treated thermoplastic resin to form a coating film. For coating, a bar with a wet coating amount = 13 μm was used. Thereafter, the layer made of the thermoplastic resin on which the coating film was formed was dried with hot air at 60 ° C. for 1 minute, and the laminated intermediate in which the layer made of silica fine particles and the resin was laminated on the layer made of the thermoplastic resin Obtained.
Further, a coating liquid (e) was applied on the layer composed of the silica fine particles and the resin. For coating, a bar having a wet coating amount of 5 μm was used. Thereafter, the laminated intermediate on which the coating film is formed is dried with hot air at 60 ° C. for 1 minute, and consists of a layer made of a thermoplastic resin (C layer), a layer made of silica fine particles and a resin (B layer), and silica fine particles. A laminated film in which layers (A layer) were sequentially laminated was obtained. Table 3 shows the configurations of the A layer and the B layer, and Table 4 shows the test results of the laminated film.

[Comparative Example 1]
<Formation of layer B>
A corona treatment was applied to the outer layer of the thermoplastic resin layer. The coating liquid (a) was applied to the surface of a layer made of a corona-treated thermoplastic resin. For coating, a bar with a wet coating amount = 13 μm was used. Thereafter, the layer made of the thermoplastic resin on which the coating film was formed was dried with hot air at 60 ° C. for 1 minute, and the laminated intermediate in which the layer made of silica fine particles and the resin was laminated on the layer made of the thermoplastic resin Obtained. The laminated intermediate is the laminated film of Comparative Example 1. Table 3 shows the configuration of the layer (B layer) made of silica fine particles and resin, and Table 4 shows the test results of the laminated film.

[Comparative Example 2]
<Formation of layer B>
A corona treatment was applied to the outer layer of the thermoplastic resin layer. The coating liquid (c) was applied to the surface of a layer made of a corona-treated thermoplastic resin. For coating, a bar with a wet coating amount = 13 μm was used. Thereafter, the layer made of the thermoplastic resin on which the coating film was formed was dried with hot air at 60 ° C. for 1 minute, and the laminated intermediate in which the layer made of silica fine particles and the resin was laminated on the layer made of the thermoplastic resin Obtained. The laminated intermediate is the laminated film of Comparative Example 2. Table 3 shows the configuration of the layer (B layer) made of silica fine particles and resin, and Table 4 shows the test results of the laminated film.

[Comparative Example 3]
<Formation of layer B>
A corona treatment was applied to the outer layer of the thermoplastic resin layer. The coating solution (d) was applied to the surface of a layer made of a corona-treated thermoplastic resin. For coating, a bar with a wet coating amount = 13 μm was used. Thereafter, the layer made of the thermoplastic resin on which the coating film was formed was dried with hot air at 60 ° C. for 1 minute, and the laminated intermediate in which the layer made of silica fine particles and the resin was laminated on the layer made of the thermoplastic resin Obtained. The laminated intermediate is the laminated film of Comparative Example 3. Table 3 shows the configuration of the layer (B layer) made of silica fine particles and resin, and Table 4 shows the test results of the laminated film.

[Comparative Example 4]
<Formation of layer A>
A corona treatment was applied to the outer layer of the thermoplastic resin layer. The coating liquid (f) was applied to the surface of the layer made of the corona-treated thermoplastic resin. For coating, a bar having a wet coating amount of 5 μm was used. Thereafter, the layer made of the thermoplastic resin on which the coating film was formed was dried with hot air at 60 ° C. for 1 minute to obtain a laminated intermediate in which the layer made of silica fine particles was laminated on the layer made of the thermoplastic resin. . The laminated intermediate is the laminated film of Comparative Example 4. Table 3 shows the configuration of the layer composed of silica fine particles (A layer), and Table 4 shows the test results of the laminated film.

※ ａ：Ｂ層に含まれる樹脂の重量％
ｂ：Ｂ層に含まれるシリカ微粒子の重量％

* A:% by weight of resin contained in layer B
b:% by weight of silica fine particles contained in layer B

  Next, Examples 3 to 6 will be described.

[Example 3]
<Formation of A layer and B layer>
A corona treatment was applied to the outer layer of the thermoplastic resin layer. A coating solution (ki) was applied to the surface of a layer made of a corona-treated thermoplastic resin to form a coating film. For coating, a bar with a wet coating amount = 13 μm was used. Thereafter, the layer made of the thermoplastic resin on which the coating film was formed was dried with hot air at 60 ° C. for 1 minute, and the laminated intermediate in which the layer made of silica fine particles and the resin was laminated on the layer made of the thermoplastic resin Obtained.
Further, a coating solution (sa) was applied on the layer composed of the silica fine particles and the resin. For coating, a bar having a wet coating amount of 5 μm was used. Thereafter, the laminated intermediate on which the coating film is formed is dried with hot air at 60 ° C. for 1 minute, and consists of a layer made of a thermoplastic resin (C layer), a layer made of silica fine particles and a resin (B layer), and silica fine particles. A laminated film in which layers (A layer) were sequentially laminated was obtained. Table 5 shows the configurations of the A layer and the B layer, and Table 6 shows the test results of the laminated film.

[Example 4]
<Formation of A layer and B layer>
A corona treatment was applied to the outer layer of the thermoplastic resin layer. The coating liquid (ku) was applied to the surface of the layer made of the corona-treated thermoplastic resin to form a coating film. For coating, a bar with a wet coating amount = 13 μm was used. Thereafter, the layer made of the thermoplastic resin on which the coating film was formed was dried with hot air at 60 ° C. for 1 minute, and the laminated intermediate in which the layer made of silica fine particles and the resin was laminated on the layer made of the thermoplastic resin Obtained.
Further, a coating liquid (shi) was applied on the layer composed of the silica fine particles and the resin. For coating, a bar having a wet coating amount of 5 μm was used. Thereafter, the laminated intermediate on which the coating film is formed is dried with hot air at 60 ° C. for 1 minute, and consists of a layer made of a thermoplastic resin (C layer), a layer made of silica fine particles and a resin (B layer), and silica fine particles. A laminated film in which layers (A layer) were sequentially laminated was obtained. Table 5 shows the configurations of the A layer and the B layer, and Table 6 shows the test results of the laminated film.

[Example 5]
<Formation of A layer and B layer>
A corona treatment was applied to the outer layer of the thermoplastic resin layer. A coating liquid was applied to the surface of the layer made of the corona-treated thermoplastic resin to form a coating film. For coating, a bar with a wet coating amount = 13 μm was used. Thereafter, the layer made of the thermoplastic resin on which the coating film was formed was dried with hot air at 60 ° C. for 1 minute, and the laminated intermediate in which the layer made of silica fine particles and the resin was laminated on the layer made of the thermoplastic resin Obtained.
Further, a coating liquid (shi) was applied on the layer composed of the silica fine particles and the resin. For coating, a bar having a wet coating amount of 5 μm was used. Thereafter, the laminated intermediate on which the coating film is formed is dried with hot air at 60 ° C. for 1 minute, and consists of a layer made of a thermoplastic resin (C layer), a layer made of silica fine particles and a resin (B layer), and silica fine particles. A laminated film in which layers (A layer) were sequentially laminated was obtained. Table 5 shows the configurations of the A layer and the B layer, and Table 6 shows the test results of the laminated film.

[Example 6]
<Formation of A layer and B layer>
A corona treatment was applied to the outer layer of the thermoplastic resin layer. A coating liquid (co) was applied to the surface of a layer made of a corona-treated thermoplastic resin to form a coating film. For coating, a bar with a wet coating amount = 13 μm was used. Thereafter, the layer made of the thermoplastic resin on which the coating film was formed was dried with hot air at 60 ° C. for 1 minute, and the laminated intermediate in which the layer made of silica fine particles and the resin was laminated on the layer made of the thermoplastic resin Obtained.
Further, a coating liquid (shi) was applied on the layer composed of the silica fine particles and the resin. For coating, a bar having a wet coating amount of 5 μm was used. Thereafter, the laminated intermediate on which the coating film is formed is dried with hot air at 60 ° C. for 1 minute, and consists of a layer made of a thermoplastic resin (C layer), a layer made of silica fine particles and a resin (B layer), and silica fine particles. A laminated film in which layers (A layer) were sequentially laminated was obtained. Table 5 shows the configurations of the A layer and the B layer, and Table 6 shows the test results of the laminated film.

※ ａ：Ｂ層に含まれる樹脂の重量％
ｂ：Ｂ層に含まれるシリカ微粒子の重量％

* A:% by weight of resin contained in layer B
b:% by weight of silica fine particles contained in layer B

[Example 7]
<Laminated film exposure test (1)>
An exposure test was conducted using the laminated film obtained in Example 4 as a covering material in a test house in Yame City, Fukuoka Prefecture (installed as an independent building so that north and south are long sides). The laminated film was coated on the frame so that the layer A of the laminated film became the inner surface of the house. (Exposure test start date: November 13, 2009)
The antifogging condition was visually observed. The observation date and time was 10:00 on October 2, 2010. The layer A surface of the laminated film was wet uniformly.

[Example 8]
<Preparation of C layer>
A layer made of a thermoplastic resin having a thickness of 100 μm in which an outer layer, an intermediate layer, and an inner layer were laminated in this order was produced by a coextrusion inflation molding method (processing temperature 180 ° C.). In addition, the weight ratio of the extrusion amount of the outer layer, the intermediate layer, and the inner layer was set to outer layer / intermediate layer / inner layer = 2/6/2. The composition of each layer is as follows.

  The outer layer is composed of A1 pellet 45.2%, A4 pellet 40.0%, B1 pellet 2.0%, MB1 pellet 2.8%, MB3 pellet 10.0% described in JP 2010-12649 A, Examples. It formed with the thermoplastic resin composition which consists of.

  The intermediate layer is a thermoplastic resin composition comprising 52.8% of A2 pellets, 20.0% of B1 pellets, 7.6% of MB1 pellets, 19.6% of MB2 pellets described in JP 2010-12649 A, Examples. Formed.

  The inner layer is a thermoplastic resin composition comprising 63.6% of A2 pellets, 20.0% of B1 pellets, 6.4% of MB1 pellets and 10.0% of MB3 pellets described in Examples in JP2010-12649A. Formed with.

<Formation of A layer and B layer>
A corona treatment was applied to the outer layer of the thermoplastic resin layer. A coating solution (ki) was applied to the surface of a layer made of a corona-treated thermoplastic resin to form a coating film. For coating, a bar with a wet coating amount = 13 μm was used. Thereafter, the layer made of the thermoplastic resin on which the coating film was formed was dried with hot air at 60 ° C. for 1 minute, and the laminated intermediate in which the layer made of silica fine particles and the resin was laminated on the layer made of the thermoplastic resin Obtained.
Further, a coating liquid (shi) was applied on the layer composed of the silica fine particles and the resin. For coating, a bar having a wet coating amount of 5 μm was used. Thereafter, the laminated intermediate on which the coating film is formed is dried with hot air at 60 ° C. for 1 minute, and consists of a layer made of a thermoplastic resin (C layer), a layer made of silica fine particles and a resin (B layer), and silica fine particles. A laminated film in which layers (A layer) were sequentially laminated was obtained.
The thicknesses of the A layer and the B layer were 0.7 μm for the B layer and 0.1 μm for the A layer.

<Laminated film exposure test (2)>
An exposure test was conducted using the laminated film obtained in Example 8 as a covering material in a test house in Shichinai-cho, Kamiiso-gun, Hokkaido (installed as an independent building so that the east-west direction is long). The laminated film was coated on the frame so that the layer A of the laminated film became the outer surface of the house. (Exposure test start date: November 22, 2009)
The condition of snowfall was observed visually. The observation date was 11:00 on January 15, 2010. A photograph taken during observation is shown in FIG.

<Laminated film exposure test (3)>
In a test house in Tarumi City, Kagoshima Prefecture, where ash fall damage is significant on Sakurajima, an exposure test was conducted using the laminated film obtained in Example 8 as a covering material. The laminated film was coated on the frame so that the layer A of the laminated film became the outer surface of the house. (Exposure start date: November 6, 2010)
The degree of dust (ash) adhesion on the outer surface of the house was visually observed. The observation date and time was around 13:00 on February 25, 2011. A photograph taken at the time of observation is shown in FIG.

[Reference Example 1]
<Exposure test of laminated film (4)>
An exposure test was conducted using a test house in Shichinai-cho, Kamiiso-gun, Hokkaido (installed as an independent building so that the east-west direction is on the long side) and using the laminated film obtained in Example 5 as a covering material. The laminated film was coated on the frame so that the layer A of the laminated film became the inner surface of the house. (Exposure test start date: November 22, 2009)
The condition of snowfall was observed visually. The observation date was 11:00 on January 15, 2010. A photograph taken during observation is shown in FIG. Comparing the results of the exposure test (2) with the results of the exposure test (4), the covering material of the exposure test (2) was less covered with snow than the covering material of the exposure test (4). .

[Reference Example 2]
<Laminated film exposure test (5)>
In a test house in Tarumi City, Kagoshima Prefecture, where ash fall damage is significant on Sakurajima, an exposure test was conducted using the laminated film obtained in Example 5 as a covering material. The laminated film was coated on the frame so that the layer A of the laminated film became the inner surface of the house. (Exposure start date: November 6, 2010)
The degree of dust (ash) adhesion on the outer surface of the house was visually observed. The observation date and time was around 13:00 on February 25, 2011. A photograph taken at the time of observation is shown in FIG. The front of the photo is the test house of the exposure test (3), and the back of the photo is the test house of the exposure test (5). Comparing the results of the exposure test (3) with the results of the exposure test (5), the coating of the exposure test (3) had less dust (ash) adhesion than the coating of the exposure test (5). .

[Example 9]
<Laminated film exposure test (6)>
The laminated film obtained in Example 4 was bent, and the coating film was intentionally damaged. An exposure test was conducted in a test house in Yame City, Fukuoka Prefecture using a scratched laminated film as a covering material. The laminated film was coated on the frame so that the layer A of the laminated film became the inner surface of the house. (Exposure test start date: November 10, 2010)
The laminated film was visually observed to evaluate the antifogging property of the laminated film. The observation date and time was around 12:00 on February 10, 2011. As a matter of course, the portion where the laminated film was not damaged was not found to have a poor antifogging property even in the portion where the laminated film was damaged.

[Example 10]
The following tests were performed on the laminated films obtained in Example 1 and Comparative Example 3.

<Anti-fogging property test for scratches>
Using a friction fastness tester RT-200 (manufactured by Daiei Kagaku Seiki Seisakusho Co., Ltd.) and steel wool (# 0000) at a load of 500 gf, the laminated film obtained in Example 1 and Comparative Example 3 were obtained. Each surface of the laminated film (A layer in the case of the laminated film of Example 1 and B layer in the case of the laminated film of Comparative Example 3) was rubbed 5 times and intentionally scratched.
A laminated film that is intentionally scratched is attached to a 34 cm long x 5 cm wide acrylic frame with a double-sided adhesive tape, and the laminated film surface (A layer or B layer) is placed in contact with the steam in the aquarium, The periphery was pasted with aluminum tape. At this time, the scratch was made to be approximately in the center in the vertical direction parallel to the horizontal direction of the acrylic frame. The acrylic frame to which the laminated film was fixed was placed on a constant temperature water tank placed in an environmental test chamber with an inclination of 10 degrees with respect to the horizontal plane. At this time, the air temperature in the environmental test chamber was 23 ° C., and the water temperature in the constant temperature bath was 40 ° C.
One day after the installation of the laminated film, the antifogging property of the scratched part was observed and judged according to the following criteria.
○: Adherence of water droplets is not observed at the scratched part.
X: Adhered water droplets are observed at the scratched part.

The test was performed with N number = 16, and the probability of occurrence of x was calculated.
As a result, in the laminated film of Example 1, the probability of occurrence of x was 38%, whereas in the laminated film of Comparative Example 3, it was 94%.

  The present invention can be used for agricultural films.

Claims (5)

A laminated film having a layer made of silica fine particles, a layer made of silica fine particles and a resin, and a layer made of a thermoplastic resin, between the layer made of the silica fine particles and the layer made of the thermoplastic resin A laminated film comprising a layer made of silica fine particles and a resin, and the layer made of silica fine particles is an outermost layer on at least one surface of the laminated film. When the total of the silica fine particles and the resin contained in the layer composed of the silica fine particles and the resin is 100% by weight, the content of the silica fine particles in the layer composed of the silica fine particles and the resin is 30 to 70% by weight, and the resin content The laminated film according to claim 1, wherein the amount is 30 to 70% by weight. The laminated film according to claim 1 or 2, wherein the layer made of the thermoplastic resin is made of a polyethylene resin. It is a structure for plant cultivation, Comprising: This structure is comprised with the coating | covering material which covers this and has formed the external shape of the said structure, This coating | covering material is any one of Claims 1-3. The structure for plant cultivation which is the laminated film described in the above, and the layer made of silica fine particles of the laminated film is the inner surface of the structure. It is a structure for plant cultivation, Comprising: This structure is comprised with the coating | covering material which covers this and has formed the external shape of the said structure, This coating | covering material is any one of Claims 1-3. A structure for plant cultivation, which is a laminated film described in 1. wherein the layer of silica fine particles of the laminated film is the outer surface of the structure.

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