JP4222531B2 - Agricultural multilayer film - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an agricultural multilayer film covering a house or a tunnel. More specifically, the present invention relates to an agricultural multilayer film having toughness and flexibility and having excellent low-temperature antifogging properties.
[0002]
[Prior art]
Various plastic films are used as covering materials for facility horticulture such as agricultural houses and tunnels. Typical examples thereof include a polyvinyl chloride film (hereinafter referred to as “Nongbi”), a polyethylene film (hereinafter referred to as “Nongpoly”), an ethylene vinyl acetate copolymer film (hereinafter referred to as “Nongbi”), and the like. Can be mentioned. Among them, agricultural bean is most frequently used because it is excellent in heat retention, transparency, toughness, anti-fogging property, house adhesion and economy.
[0003]
However, the agricultural bean has a defect that the additive contained in the film gradually oozes out on the film surface, thereby causing stickiness on the film surface and deteriorating workability and dust resistance. In addition, the problem that harmful gases are generated when agricultural beans are incinerated and discarded has been taken up, and agricultural substitutes that do not generate harmful gases are desired.
[0004]
On the other hand, Agricultural Poly and Agricultural Vinegar are superior to Agricultural Bi in terms of workability, dust resistance and ease of disposal, but inferior in heat retention, antifogging properties, toughness, etc. Improvements have been desired.
[0005]
Japanese Patent Application Laid-Open No. 60-104141 discloses a technique for adding a specific filler having infrared absorptivity in order to improve the heat retention of these agricultural poly and agricultural vinegar. In order to improve anti-fogging properties and toughness, JP-A-58-90960 discloses linear low density polyethylene as an outer layer (a layer in contact with the outside air of a house or tunnel) and ethylene-vinyl acetate as an intermediate layer. Copolymers, olefin-vinyl alcohol copolymers, and laminated films for agriculture using linear low density polyethylene or ethylene-vinyl acetate copolymer for the inner layer (layer in contact with the air inside the house or tunnel) have been proposed. .
[0006]
These methods have made it possible to bring the antifogging property and infrared absorption property of the film itself closer to that of agricultural behaviour, but in both cases the film has poor flexibility and lacks adhesion to agricultural houses and maintains airtightness. Sufficient heat retention is not obtained because it does not hit. Further, when the film is folded, the film is bulky because it does not have flexibility, so that the workability is poor, and the transportation efficiency and the storage efficiency are greatly reduced.
[0007]
In order to improve these flexibility, ethylene-acetic acid with increased vinyl acetate content in the inner layer (layer in contact with the air inside the house or tunnel) and outer layer (layer in contact with the air outside the house or tunnel) of the multilayer film It is conceivable to use a vinyl copolymer or a low density ethylene-α-olefin copolymer, but an ethylene vinyl acetate copolymer having a high vinyl acetate content has a low melting point, and this was used. There was a problem that the films were fused. In order to reduce the density of a copolymer obtained by copolymerizing ethylene and α-olefin using a multisite catalyst such as a conventional Ziegler catalyst, a copolymer having a high α-olefin content is used. Although it is necessary, such an α-olefin cannot be uniformly copolymerized, and the film using the obtained copolymer is sticky, the films are in close contact with each other, and are not practically usable. .
[0008]
On the other hand, in recent years, development of linear low density polyethylene which is an ethylene-α-olefin copolymer by polymerization using a single site catalyst instead of the conventional multisite catalyst has progressed, and Japanese Patent Application Laid-Open No. 09-052332 describes the density. 0.925 to 0.940 g / cm^ThreeOuter layer made of an ethylene-α-olefin copolymer having a density of 0.880 to 0.910 g / cm^ThreeAn intermediate layer comprising an ethylene-α-olefin copolymer and a density of 0.905 to 0.930 g / cm^ThreeAn agricultural laminated film in which an inner layer made of an ethylene-α-olefin copolymer is laminated is disclosed in Japanese Patent Application Laid-Open No. 08-276542 with an ethylene-vinyl acetate copolymer as an intermediate layer, and a single inner layer and an outer layer. An agricultural multilayer film using an ethylene-α-olefin copolymer obtained by using a site catalyst has been proposed.
[0009]
Although these laminated films for agriculture have improved toughness but lack flexibility, the problems of workability, storage efficiency, and transport efficiency remain unresolved.
[0010]
As a result of intensive studies to improve the problems of the prior art, the present inventors have used a thermoplastic resin having a high tensile elastic modulus for the intermediate layer and a specific ethylene-α-olefin having a low tensile elastic modulus for the inner and outer layers. It has been found that an agricultural multilayer film using a copolymer can improve the above problems, but an agricultural multilayer film using an ethylene-α-olefin copolymer polymerized by a single site catalyst as an inner layer is an agricultural house. When the inside is in a high-humidity and low-temperature environment, the anti-fogging property is not sufficiently developed, causing pests, and there is concern about poor growth of crops due to a decrease in the transmittance of sunlight.
[0011]
[Problems to be solved by the invention]
An object of the present invention is to provide an agricultural multilayer film having toughness and good anti-fogging property even at low temperatures, excellent flexibility, airtightness of a house, workability, and transportation / storage efficiency. There is.
[0012]
As a result of intensive studies to improve the problems of the prior art, the present inventors have found that each layer has a specific composition and is composed of at least an inner layer A, an intermediate layer B, and an outer layer C. Has found that the above-mentioned problems can be improved, and has completed the present invention based on this finding.
[0013]
[Means for Solving the Problems]
The present invention has the following configuration.
(1) An ethylene-vinyl acetate copolymer (a) which is an agricultural multilayer film composed of at least an inner layer A, an intermediate layer B, and an outer layer C, wherein the inner layer A has a vinyl acetate content of 2 to 10% by weight. The density of the outer layer C polymerized using a single site catalyst (d_c) 0.88-0.92g / cm^ThreeThe ethylene-α-olefin copolymer (c) is used as a main component, and the tensile modulus when the intermediate layer B is a single-layer film is the ethylene-α-olefin copolymer (c ) Is a multilayer film for agriculture composed of a composition comprising as a main component a thermoplastic resin (b) having a tensile modulus higher than that of a single layer film and having 1.0 to 10% by weight of an antifogging agent added thereto.
(2) Density (d_b1) 0.90 to 0.94 g / cm^ThreeAn ethylene-α-olefin copolymer (b1), and d_b1> D_cThe agricultural multilayer film according to item (1), wherein
(3) The composition constituting the inner layer A, the intermediate layer B and the outer layer C has a BET specific surface area of 5 to 50 m²/ G inorganic filler is added in an amount of 0.05 to 5% by weight, 1 to 10% by weight, and 1 to 10% by weight, and the amount of the inorganic filler added to the composition constituting the outer layer C constitutes the inner layer A. The agricultural multilayer film according to (1) or (2), wherein the amount is greater than the amount added to the composition.
(4) The antifogging agent added to the composition constituting the intermediate layer B is one or more selected from the group of neutralized salts of compounds represented by the following formula 1 and their organic acids. The agricultural multilayer film according to any one of (1) to (3).
[0014]
[Chemical formula 2]
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the agricultural multilayer film according to the present invention will be described in detail.
The agricultural multilayer film of the present invention comprises an ethylene-vinyl acetate copolymer (a), ethylene-α-olefin copolymers (c) and (b1), a thermoplastic resin (b), an antifogging agent and an inorganic filler. It is a multilayer film of 3 or more layers comprised from the composition which has any 1 type (s) or 2 or more types as a component. The “main component” of the composition constituting each layer according to the present invention refers to a component contained in the composition at 50% by weight or more.
[0016]
[Ethylene-vinyl acetate copolymer] The ethylene-vinyl acetate copolymer (a) used in the composition constituting the inner layer A in the agricultural multilayer film of the present invention is obtained by subjecting ethylene and vinyl acetate to a known high-pressure radical polymerization process. The melt flow rate (hereinafter referred to as MFR) produced by reaction and measured according to JIS K 7210 is 0.1 to 10 g / 10 min, preferably 0.5 to 5 g / 10 min. If the MFR is less than 0.5 g / 10 min, the moldability of the film, particularly the extrudability and high-speed stretchability may be deteriorated. If the MFR exceeds 5 g / 10 min, the moldability of the film, particularly in inflation molding. Bubble stability may be lacking.
[0017]
The ethylene-vinyl acetate copolymer has a vinyl acetate content of 2 to 10% by weight, and if it is less than 2% by weight, the desired antifogging property of the resulting agricultural multilayer film, particularly at low temperatures, is achieved. It cannot be obtained and the anti-fogging sustainability is also lowered. On the other hand, when the content exceeds 10% by weight, the above-mentioned films may be in close contact with each other, or when they are left outdoors, they may be stored by sunlight and the films may be fused.
[0018]
[Ethylene-α-olefin copolymer] Ethylene-α-olefin copolymers (b1) and (c) used as main components of the composition constituting the intermediate layer B and the outer layer C in the agricultural multilayer film of the present invention , Is a random copolymer of ethylene and an α-olefin having 3 to 20 carbon atoms, and is copolymerized using a single site catalyst such as a metallocene catalyst.
[0019]
Examples of the α-olefin having 3 to 20 carbon atoms include propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene, 1-dodecene, 1- Examples include tetradecene, 1-hexadecene, 1-octadecene, and 1-eicocene. The content of the α-olefin in the random copolymer is 1 to 45% by weight, preferably 2 to 35% by weight.
[0020]
As the single site catalyst, a combination of a metallocene compound of Group IV or V transition metal of the periodic table such as titanium, zirconium, hafnium, vanadium, and an organoaluminum compound and / or an ionic compound is used.
[0021]
As the metallocene compound, a compound in which at least one cyclopentadienyl group, a substituted cyclopentadienyl group, hydrocarbyl silicon or the like is crosslinked, and a compound in which the cyclopentadienyl group is crosslinked with oxygen, nitrogen, or phosphorus atoms are arranged. Any known metallocene compound as a ligand can be used.
[0022]
Specific examples of these metallocene compounds include dimethylsilyl (2,4-dimethylcyclopentadienyl) (3 ′, 5′-dimethylcyclopentadienyl) zirconium dichloride, dimethylsilyl (2,4-dimethylcyclopentadienyl). Silicon) bridged metallocene compounds such as (enyl) (3 ', 5'-dimethylcyclopentadienyl) hafnium dichloride, ethylenebisindenylzirconium dichloride, ethylenebisindenylhafnium dichloride, ethylenebis (methylindenyl) zirconium dichloride, ethylene Examples thereof include indenyl-based bridged metallocene compounds such as bis (methylindenyl) hafnium dichloride.
[0023]
The organoaluminum compound used in combination with the metallocene compound is represented by the general formula-(Al (R) O)._nA linear or cyclic polymer represented by-(R is a hydrocarbon group having 1 to 10 carbon atoms, including those partially substituted with a halogen atom and / or RO group. N is the degree of polymerization. Specific examples include methylalumoxane, ethylalumoxane, and isobutylethylalumoxane, in which R is a methyl, ethyl, or isobutyl group, respectively.
[0024]
Furthermore, other organoaluminum compounds include trialkylaluminum, dialkylhalogenoaluminum, sesquialkylhalogenoaluminum, alkenylaluminum, dialkylhydroaluminum, sesquialkylhydroaluminum and the like.
[0025]
As an ionic compound, a general formula
[Q]^{m +}  [Y]^m-      (M is an integer of 1 or more)
Q in the formula is a cation component of an ionic compound, and examples thereof include a carbonium ion, a tropylium cation, an ammonium cation, an oxonium cation, a sulfonium cation, and a phosphonium cation. Y is an anionic component of an ionic compound, which is a component that reacts with a metallocene compound to become a stable anion, and is an organic boron compound anion, an organic aluminum compound anion, an organic gallium compound anion, an organic phosphorus compound anion, an organic Examples include arsenic compound anions and organic antimony compound anions.
[0026]
As a copolymerization method of ethylene and α-olefin performed using a single site catalyst, a known polymerization method is used, and examples thereof include a gas phase polymerization method, a slurry polymerization method, and a solution polymerization method.
[0027]
The number average molecular weight of the ethylene-α-olefin copolymer copolymerized using such a single site catalyst is 1 × 10.^Four~ 100 × 10^FourThe Q value, which is the ratio between the weight average molecular weight and the number average molecular weight, is in the range of 1.5 to 3.5, and when copolymerized using a multisite catalyst such as a conventional Ziegler-Natta catalyst In comparison, the molecular weight distribution is narrow, even those with a high content of α-olefin are uniformly polymerized, and there are many tie molecules between lamellae, so there are few low molecular weight components and excellent blocking resistance, Excellent transparency, impact resistance, and toughness.
The density of the ethylene-α-olefin copolymer is usually 0.870-0.960 g / cm.^ThreeIt is in the range.
[0028]
In the agricultural multilayer film of the present invention, the thermoplastic resin (b) used in the composition constituting the intermediate layer B has a tensile elastic modulus as a main component of the composition constituting the outer layer C when a single layer film is formed. It is a thermoplastic resin larger than the tensile elastic modulus when the ethylene-α-olefin copolymer (c) is a single layer film. When the tensile elastic modulus of the single layer film obtained from the thermoplastic resin (b) is equal to or smaller than the tensile elastic modulus of the single layer film obtained from the ethylene-α-olefin copolymer (c), it is obtained. There is a possibility that the toughness of the agricultural multilayer film to be produced is lowered.
[0029]
Examples of the thermoplastic resin (b) include polyethylene resins such as known high-density polyethylene, low-density polyethylene, and linear low-density polyethylene, as well as polypropylene resins, polyester resins, and polyamide resins. From the viewpoint of good adhesion when B is laminated with the inner layer A and the outer layer C, an ethylene-α-olefin copolymer polymerized using the above-mentioned single-site catalyst is preferably used.
[0030]
The ethylene-α-olefin copolymer (b1) suitably used for the composition constituting the intermediate layer B has a density (d_b1) Is 0.90 to 0.94 g / cm^ThreeIt is. Density (d_b1) Is 0.90g / cm^ThreeIf it is less than 1, the tensile elastic modulus of the obtained monolayer film is difficult to achieve the desired value, and 0.94 g / cm.^ThreeIn the case of exceeding the above range, the resulting agricultural multilayer film has insufficient flexibility.
[0031]
In the agricultural multilayer film of the present invention, the density (d) of the ethylene-α-olefin copolymer (c) used as the main component of the composition constituting the outer layer C_c) Is 0.88-0.92g / cm^ThreeAnd d_c0.88g / cm^ThreeIf it is less than 1, the film-forming processability is inferior, and since the melting point is low, heat may be stored and fused with sunlight. 0.92g / cm^ThreeIn the case where it exceeds the range, the desired flexibility may not be obtained.
The d_cAnd d_b1D_c<D_b1It is necessary to be in a relationship. d_c≧ d_b1In this case, even if the obtained multilayer film has the same tensile elastic modulus, the flexibility is inferior, so that the airtightness is not maintained as an agricultural house, and sufficient heat retaining properties cannot be obtained. In addition, when the film is folded, the film is not flexible so that it is bulky and the workability is poor, resulting in a decrease in transport efficiency and storage efficiency.
[0032]
The ethylene-α-olefin copolymers (c) and (b1) polymerized by the single-site catalyst used in the present invention have an MFR of 0.2 to 20 g / 10 at 190 ° C. and a load condition of 2.16 kgf. The range of minutes is suitably used for films, and there may be two or more melting peaks by differential scanning calorimetry (DSC), but in order to improve the transparency and toughness of the film It is desirable to have one.
[0033]
[Antifogging agent] In the agricultural multilayer film of the present invention, 1 to 10% by weight of an antifogging agent is added to the composition constituting the intermediate layer B. If it is less than 1% by weight, the antifogging sustaining effect is not sufficient, and if it exceeds 10% by weight, there are problems such as blowing to the surface of the film and the film becoming opaque or foaming during film formation. Arise. The antifogging agent may be added not only to the intermediate layer B but also to the inner layer A or the inner layer A and the outer layer C as necessary.
[0034]
Examples of the antifogging agent include nonionic surfactants, cationic surfactants, anionic surfactants, amphoteric surfactants, etc., the degree of esterification of the antifogging agent, the chain length of the alkyl group, and the alkylene oxide. Those obtained by changing the number of moles added, or their purity. Examples thereof include partial carboxylic acid esters of polyhydric alcohols such as sorbitan monolaurate, diglycerin sesquilaurate, glycerin monooleate, polyhydric alcohols such as polyoxyethylene sorbitan monolaurate and polyoxyethylene sorbitan monooleate. Examples thereof include polyoxyethylene derivatives of partial carboxylic acid esters, amines and fatty acid amides. Among them, neutralized salts of compounds represented by the following formula 1 and their organic acids are preferably used, and in particular, exhibit excellent antifogging properties and durability at low temperatures in the agricultural multilayer film of the present invention. It became clear.
[0035]
[Chemical 3]
[0036]
Examples of the compound represented by the above formula 1 include amine compounds such as polyoxyethylene (8 mol) stearylamine, polyoxyethylene (2 mol) laurylamine, polyoxyethylene (2 mol) tallow amine, polyoxyethylene laurylamide Amide compounds such as polyoxyethylene stearylamide, and fatty acid esters of these amine compounds and amide compounds with fatty acids such as lauric acid, stearic acid, behenic acid, and oleic acid. Examples of the organic acid include carboxylic acid, sulfonic acid, phenol carboxylic acid and the like, and among them, carboxylic acid is preferable in terms of reactivity and stability with the compound. Specific examples include lauric acid, stearic acid, behenic acid, oleic acid and benzoic acid.
These antifogging agents are used alone or in combination of two or more.
[0037]
[Inorganic filler] In the agricultural multilayer film of the present invention, it is preferable to add an inorganic filler to the composition constituting the inner layer A, the intermediate layer B and the outer layer C.
In general, in the field of agricultural films, inorganic fillers are used for the purpose of imparting heat retention performance and the purpose of improving the adhesion between the films, but it is possible to control the development of antifogging properties and antifogging durability. .
In the multilayer film for agriculture of the present invention, the amount of the inorganic filler added to the composition constituting the outer layer C is preferably larger than the amount of the inorganic filler added to the composition constituting the inner layer A. As a result, it becomes difficult for the anti-fogging agent and the anti-fogging agent to be deposited on the surface of the outer layer C, and the durability of the anti-fogging and anti-fogging properties is increased.
[0038]
The amount of the inorganic filler added to the composition constituting the inner layer A is preferably 0.05 to 5% by weight. When the amount added is less than 0.05% by weight, the antifogging agent and the antifogging agent are quickly applied to the surface of the inner layer A. Therefore, if the amount exceeds 5% by weight, the anti-fogging agent or the anti-fogging agent is not sufficiently transferred and the anti-fogging durability is not sufficiently developed. The amount of the inorganic filler added to the composition constituting the intermediate layer B and the outer layer C is preferably 1 to 10% by weight, and if the added amount is less than 1% by weight, it is difficult to retain the antifogging agent or the antifogging agent, so If the amount exceeds 10% by weight, mechanical properties and transparency may be deteriorated.
[0039]
As said inorganic filler, the BET specific surface area measured according to JIS Z 8830 is 5-50 m.²/ G, preferably 5-20m²/ G is preferably used. BET specific surface area is 50m²When exceeding / g, an antifogging agent or an antifogging agent is adsorbed, and the desired antifogging performance or antifogging performance cannot be obtained. 5m²When the amount is less than / g, the adsorption to the filler decreases, so that the transition of the antifogging agent and the antifogging agent to the film surface proceeds quickly, the film becomes sticky, and the antifogging and antifogging durability is maintained. It becomes insufficient.
[0040]
Specific examples of the inorganic filler include silicate compounds such as silicon oxide, magnesium silicate, aluminum silicate, and calcium silicate, aluminosilicate compounds such as calcium aluminosilicate, sodium aluminosilicate, and potassium aluminosilicate, alumina, sodium aluminate, and aluminum. Aluminum such as potassium acid and calcium aluminate
Examples thereof include acid compounds, calcium carbonate, lithium / aluminum composite hydroxide salts represented by the following formulas 2 and 3 and hydrotalcites represented by the following formula 4, and these may be used alone or in combination of two or more. Used.
[0041]
[Formula 4]
[Al₂Li (OH)₆]₂(A^n-) ・ MH₂O-Formula 2
(In the formula, m represents a number of 3 or less.)
[0042]
[Chemical formula 5]
(Where M²⁺Is a divalent metal, m is a number in the range of 0 ≦ m <5, x is a number in the range of 0 ≦ x <1, and y is a number in the range of 2 ≦ y ≦ 4. )
[0043]
[Chemical 6]
M²⁺ _1-xAl_x(OH)₂(A^n-)_{x / 2}・ MH₂O-Formula 4
(Where M²⁺Is Mg²⁺, Ca²⁺And Zn²⁺At least one divalent metal ion selected from the group consisting of A^n-Is an n-valent anion, x and m satisfy the following conditions: 0 <x <0.5, 0 ≦ m ≦ 2. )
[0044]
[Other components] In the agricultural multilayer film of the present invention, various materials may be added to the composition constituting the inner layer A, the intermediate layer B, and the outer layer C as long as the object of the present invention is not impaired. In order to improve the film forming processability, a known thermoplastic resin such as a high-pressure low-density polyethylene can be added to the composition constituting each layer. In order to improve flexibility, elastic copolymers such as ethylene-diene elastic copolymers, ethylene-propylene elastic copolymers, styrene-butadiene elastic copolymers polymerized with a single site catalyst or a known multi-site catalyst are also used. A polymer may be added. In addition, known hindered amine weathering agents, UV absorbers, antifogging agents (fluorine surfactants), antistatic agents, lubricants, antioxidants, heat stabilizers, antibacterial agents, A pigment | dye, a coloring agent, etc. can be mix | blended.
[0045]
The thickness of the agricultural multilayer film of the present invention varies depending on the place of use, the service life, and the like, but generally about 0.05 to 0.3 mm is preferably used. The thickness Ta of the inner layer, the thickness Tb of the intermediate layer, and the thickness Tc of the outer layer are not particularly limited, but Ta: Tb: Tc is preferably in the range of 1-5: 1 to 5: 1-5.
[0046]
The agricultural multilayer film of the present invention can be produced by a known technique such as an inflation method or a T-die method, and may be subjected to corona discharge treatment for the purpose of improving the antifogging effect after production. Further, in addition to the intermediate layer B, it is a multilayer film of four or more layers in which an intermediate layer D provided with heat retention, an intermediate layer E for improving anti-fogging property, an intermediate layer F containing a recycled material, and the like are laminated. It doesn't matter. Further, a dust-proof coating agent or an anti-fogging coating agent may be applied and dried to form a coating film on the surface.
The multilayer film for agriculture of the present invention may be transparent, pear or semi-pear, and used for mulching purposes other than covering for agricultural houses (greenhouses), tunnels, and bagging. You may do it.
[0047]
【Example】
Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples, but the present invention is not limited thereto. In addition, evaluation of the multilayer film for agriculture in an Example and a comparative example was implemented as follows.
[0048]
1) Tensile modulus (Young's modulus): The tensile modulus in the machine direction and the transverse direction of the film sample was measured according to ASTM D882, and the average value of both was shown.
2) Tensile strength: Based on JIS K 7113, the tensile breaking strength in the longitudinal direction and the transverse direction was measured, and the average value of both was shown.
3) Flexibility: Using a sample having a width of 10 mm and a length of 100 mm, horizontally supporting 50 mm from the end in the sample length direction to the center, leaving the remaining 50 mm in a free state, from the support end to the sample tip The horizontal distance was measured as an index of flexibility. It shows that the flexibility is improved as the horizontal distance becomes shorter.
4) Low-temperature anti-fogging property; using a water bath having a skylight with a tilt of 10 degrees and a diameter of 7.6 cm, a film sample is fixed to the skylight of the water bath, and the condition is 12 under the conditions of an environmental temperature of 23 ° C and a water temperature of 45 ° C After being left for days, the samples were left for 2 days under conditions of an environmental temperature of 5 ° C. and a water temperature of 15 ° C., and the antifogging property of the surface of the sample on the water bath side was visually judged on a five-step basis to evaluate the low temperature antifogging property. The larger the 5-step number, the better the low-temperature antifogging property.
<Evaluation criteria for low-temperature anti-fogging properties>
Evaluation 5: Formation of a uniform water film without adhesion of water droplets.
Evaluation 4: Water droplet adhesion is less than 15%.
Evaluation 3: Adhesion of water droplets is less than 40%.
Evaluation 2: Adhesion of water droplets is less than 65%.
Evaluation 1: Water droplet adhesion is 65% or more.
5) Anti-fogging durability; using a water bath having a skylight with a tilt of 10 degrees and a diameter of 3 inches, fixing the film samples obtained in Examples and Comparative Examples to the skylight of the water bath, It was allowed to stand day and night under the condition of a water temperature of 45 ° C., and the period during which the antifogging property was maintained was visually evaluated. The longer the number of days, the better the antifogging sustainability.
[0049]
The thermoplastic resin used for each layer is shown below. S-LLDPE represents an ethylene-α-olefin copolymer polymerized by a single site catalyst, and M-LLDPE represents an ethylene-α-olefin copolymer polymerized by a multi-site catalyst.
[0050]
In addition, each characteristic of the said thermoplastic resin was measured on condition of the following.
1) MFR; in accordance with JIS K 7210, ethylene copolymer resins from (1) to (8) are 190 ° C. and 2.16 kgf, and (9) polypropylene composition is 230 ° C. 2. Measured at 16 kgf.
2) Density: Measured according to JIS K 7112.
3) Tensile modulus (Young's modulus): longitudinal direction of a film having a thickness of 50 μm formed using a 40 mmφ single-layer inflation film forming apparatus under conditions of an extrusion temperature of 180 ° C., a blow ratio of 1.5, and a film forming speed of 15 m / min. Was measured according to ASTM D882.
[0051]
Examples 1-5, Comparative Examples 1-5
A 0.1 mm thick multilayer film was molded at a molding temperature of 190 ° C. and a blow ratio of 2.5 using a three-type three-layer inflation extruder having three 50 mmφ extruders.
The compounding example and evaluation result of each multilayer film are shown in Tables 1-3.
[0052]
In addition, as for the compounding example of each multilayer film, except the content of Tables 1-2, hindered amine-type weathering agent 0.5 weight% in the outer layer C, ultraviolet absorber 0.05 weight%, phenol-type stabilizer 0.1 weight%, Phosphorus stabilizer 0.1% by weight, anti-blocking agent 0.05% by weight, intermediate layer B 0.5% by weight of hindered amine weathering agent, UV absorber 0.05% by weight, fluorine surfactant 0 0.2% by weight, 0.1% by weight of phenol-based stabilizer, 0.1% by weight of phosphorus-based stabilizer, hindered amine-based weathering agent 0.5% by weight, UV absorber 0.05% by weight, fluorine 0.2% by weight of a surfactant, 0.1% by weight of a phenol stabilizer, 0.1% by weight of a phosphorus stabilizer, and 0.05% of an antiblocking agent were added.
[0053]
[Table 1]
[0054]
[Table 2]
[0055]
【The invention's effect】
Since the agricultural multilayer film of the present invention is excellent not only in toughness but also in flexibility, it is possible to improve spreading / recovering workability and transportation / storage efficiency, and to improve heat retention by improving the airtightness of the house. Moreover, by using an ethylene-vinyl acetate copolymer as the inner layer on the inner surface side of the house and using a specific inorganic filler and a specific antifogging agent, there has been a concern in the environment of specific conditions of low temperature and high humidity. Since it becomes possible to eliminate the antifogging defect, it can be suitably used as a covering material for agriculture such as a house or a tunnel.

Claims (4)

A multilayer film for agriculture composed of at least an inner layer A, an intermediate layer B and an outer layer C, wherein the inner layer A is mainly composed of an ethylene-vinyl acetate copolymer (a) having a vinyl acetate content of 2 to 10% by weight. The outer layer C is composed mainly of an ethylene-α-olefin copolymer (c) having a density (d _c ) of 0.88 to 0.92 g / cm ³ polymerized using a single site catalyst. It is comprised from the composition used as a component, and when the intermediate layer B is a single layer film, the tensile elastic modulus is larger than the tensile elastic modulus when the ethylene-α-olefin copolymer (c) is a single layer film. An agricultural multilayer film composed of a composition comprising a thermoplastic resin (b) as a main component and an antifogging agent added in an amount of 1.0 to 10% by weight. An ethylene-α-olefin copolymer having a density (d _b1 ) of 0.90 to 0.94 g / cm ^{3 obtained} by polymerizing a thermoplastic resin as a main component of the composition constituting the intermediate layer B using a single site catalyst. a (b1), and, d _b1> agricultural multi-layer film according to claim 1, wherein the d _c. With respect to the composition constituting the inner layer A, the intermediate layer B and the outer layer C, the inorganic filler having a BET specific surface area of 5 to 50 m ² / g is 0.05 to 5% by weight, 1 to 10% by weight and 1 to 10%, respectively. The agricultural multilayer film according to claim 1 or claim 2, wherein the amount of the inorganic filler added to the composition constituting the outer layer C of the inorganic filler is larger than the amount added to the composition constituting the inner layer A. The antifogging agent added to the composition constituting the intermediate layer B is one or more selected from the group of neutralized salts of compounds represented by the following formula 1 and their organic acids: The agricultural multilayer film according to any one of 1 to 3.