NL2023910B1

NL2023910B1 - Agricultural film and agricultural and horticultural facility

Info

Publication number: NL2023910B1
Application number: NL2023910A
Authority: NL
Inventors: Katayama Shingo
Original assignee: Sumitomo Chemical Co; Santerra Co Ltd
Priority date: 2018-10-05
Filing date: 2019-09-26
Publication date: 2020-08-14
Also published as: JP2020058247A; NL2023910A; ES2765773R1; JP6502567B1; ES2765773A2; KR102140923B1; CN110999678A; KR20200039596A

Abstract

To provide an agricultural film that scatters a large amount of light in summer (during Which sunlight is strong) and that is not easily broken and is easy to handle, an agricultural film includes at least one layer including a continuous phase and a disperse phase, the agricultural film satisfying (A) and (B) below, (A) the area of a cross section of a portion of the disperse phase for which portion an equivalent circle diameter is not less than 1 pm and not more than 10 um having a proportion of not less than 1% and not more than 30% with respect to the area of a cross section of the at least one layer, and (B) the agricultural film haVing a birefringence indeX An of not more than 1.15 >< 10'

Description

1 - Description Title of Invention

AGRICULTURAL FILM AND AGRICULTURAL AND

HORTICULTURAL FACILITY Technical Field

[0001] The present invention relates to an agricultural film and an agricultural and horticultural facility.

Background Art

[0002] Patent Literature 1 discloses a porous film that is made of a resin composition including (iJ a base resin of which the birefringence index An as measured in conformity with JIS K 7142 is An < 0.9 x 10-® and (ii) a filler contained in the base resin and that is produced by stretching a film formed of the resin composition.

[0003] Patent Literature 2 discloses an agricultural film that includes, as an intermediate layer, a layer containing (i) an ethylene-vinyl acetate copolymer that contains 15% by weight to 30% by weight of a monomeric unit based on vinyl acetate and (ii) particles of a methyl methacrylate- styrene copolymer which particles have an average particle

I. diameter of 3 pm to 15 pm. This is to allow the agricultural film to scatter more light in summer (during which sunlight is strong]. Citation List [Patent Literature]

[0004] [Patent Literature 1] Japanese Patent Application Publication, Tokukai, No. 2007-238822 [Patent Literature 2] Japanese Patent Application Publication, Tokukai, No. 2014-209903 Summary of Invention Technical Problem

[0005] An agricultural film may be torn or broken as a result of, in a case where the agricultural film is spread out to provide an agricultural and horticultural facility, stress being concentrated on that portion of the agricultural film which is in contact with a frame. The porous film disclosed in Patent Literature 1 can be torn or broken easily due to its porosity. The porous film is thus not easy to handle in a case where the porous film is spread out in an agricultural and horticultural facility.

-3- There is also a demand for an agricultural film that is less easily broken and is easier to handle than the agricultural film disclosed in Patent Literature 2.

[0006] An aspect of the present invention has an object to provide a new agricultural film that scatters a large amount of light in summer (during which sunlight is strong) and that is not easily broken and is easy to handle.

Solution to Problem

[0007] In order to attain the above object, an agricultural film in accordance with an embodiment of the present invention includes: at least one layer including a continuous phase and a disperse phase, the agricultural film satisfying (A) and (B) below, (A) in a cross section of the agricultural film which cross section is taken along a direction perpendicular to a surface of the agricultural film and parallel to a slow axis in a plane of the agricultural film, an area of a cross section of a portion of the disperse phase for which portion an equivalent circle diameter is not less than 1 pm and not more than 10 pm having a proportion of not less than 1% and not more than 30% with respect to an area of a cross section of the at least one layer, and (B) the agricultural film having a birefringence index An of not more than 1.15 x 10-3.

- 4 =

[0008] Another, preferable embodiment of the present invention is an agricultural and horticultural facility including: an agricultural and horticultural facility frame; and the agricultural film being spread out on the agricultural and horticultural facility frame.

Advantageous Effects of Invention

[0009] Aspects of the present invention provide (iJ an agricultural film that scatters a large amount of light in summer (during which sunlight is strong) and that is not easily broken and is easy to handle and (ii) a method for producing the agricultural film.

Description of Embodiments

[0010] The description below deals with an embodiment of the present invention in detail.

[0011] Agricultural film An agricultural film in accordance with an embodiment of the present invention has a birefringence index An of not more than 1.15 x 10-3 and includes at least one layer including a continuous phase and a disperse phase. An agricultural film in accordance with an

-5- embodiment of the present invention is suitably usable as, for example, a film to be spread out outside or inside a greenhouse for plant cultivation or a covering material for a tunnel.

[0012] Birefringence index The term "birefringence index An" as used herein refers to a value calculated on the basis of the formula (1) below from an in-plane retardation (in-plane phase difference) Re and the overall thickness d of the film, the in-plane retardation Re being measured with use of a phase difference measuring device (such as a KOBRA series device, available from Oji Scientific Instruments Co., Ltd.; measurement wavelength: 586 nm) that uses a parallel nicols rotation method as a measurement principle.

An (birefringence index) = Re / d (overall thickness) (1) The birefringence index An is not more than 1.15 x 10-3, preferably not more than 1.0 x 10-3, most preferably not more than 0.8 x 10-3. A birefringence index An of not more than 1.15x10-3 allows the agricultural film to be stretched better in the machine direction (MD) typically in a case where the agricultural film is spread out to provide

-6 - an agricultural and horticultural facility. This suitably prevents an agricultural film from, in a case where the agricultural film has been pulled strongly in a horizontal direction when the agricultural film is to be spread out in an agricultural and horticultural facility, being broken or torn at a portion in contact with a frame of the agricultural and horticultural facility. This in turn allows production of an agricultural film that is easier to handle. The lower limit of the birefringence index An is not limited to any particular value. The birefringence index An is, however, preferably not less than 0.05 x 10-3.

[0013] In a case where the agricultural film consists only of a layer including a continuous phase and a disperse phase, the birefringence index An of that layer can simply be evaluated as the birefringence index of an agricultural film in accordance with an aspect. In a case where the agricultural film further includes a layer(s) (that is, another layer described later) other than a layer including a continuous phase and a disperse phase, the birefringence index of the combination of all the layers can simply be evaluated as the birefringence index of an agricultural film in accordance with an aspect.

[0014] An agricultural film having the above birefringence

7 - index An may be produced through appropriate selection of raw materials and appropriate adjustment of production conditions. The agricultural film may include a layer including a continuous phase and a disperse phase (and a layer(s} other than the layer including a continuous phase and a disperse phase) made of a resin composition as a typical raw material for an agricultural film. The layer including a continuous phase and a disperse phase may be made of, in particular, an appropriate combination of (i) a thermoplastic resin for the continuous phase and (ii) at least one selected from the group consisting of organic particles, inorganic particles, and a thermoplastic resin for the disperse phase. Preferable raw materials for the continuous phase and the disperse phase will be described later under "Layer including a continuous phase and a disperse phase". The layer other than the layer including a continuous phase and a disperse phase may be made of a commonly used thermoplastic resin, and is preferably made of a polyolefin-based resin (hereinafter, the layer other than the layer including a continuous phase and a disperse phase is referred to also as "polyolefin-based resin layer"). Preferable production conditions will be described later under "Method for producing agricultural film".

[0015] Haze value

_8 - The term "haze value" as used herein refers to a value measured in conformity to JIS K 7136:2000 for measurement conditions other than temperature with use of THM-150TL, a temperature controllable haze meter available from Murakami Color Research Laboratory Co., Ltd. Light scattering of a film as described herein may be evaluated on the basis of a haze value.

[0016] An agricultural film in accordance with an embodiment of the present invention has a haze value at 40°C which haze value is preferably not less than 15%, more preferably not less than 20%. A haze value of not less than 15% at 40°C allows the agricultural film to suitably scatter light incident thereon in summer (during which the amount of sunlight is large).

[0017] For an agricultural film in accordance with an embodiment of the present invention, the layer including a continuous phase and a disperse phase has a thickness of preferably not less than 1 pm, more preferably not less than 30 pm, to allow the agricultural film to scatter more light in summer (during which the air temperature reaches a temperature close to 40°C). Further, the thickness is preferably not more than 500 1m, more preferably not more than 300 pm, to allow the agricultural film to be lighter in

- 9g weight and easier to handle.

[0018] Layer consisting of a continuous phase and a disperse phase The layer including a continuous phase and a disperse phase is a main layer included in an agricultural film in accordance with an aspect. A layer simply expressed herein as such refers to the layer including a continuous phase and a disperse phase, unless otherwise stated.

[0019] In a cross section of an agricultural film in accordance with an embodiment of the present invention which cross section is taken along a direction perpendicular to a surface of the agricultural film and parallel to the slow axis in a plane of the agricultural film, the area of a cross section of a portion of the disperse phase for which portion the equivalent circle diameter is not less than 1 pm and not more than 10 pm has a proportion of preferably not less than 1% and not more than 30%, more preferably not less than 2% and not more than 25%, with respect to the entire area of a cross section of the layer. The slow axis in the film plane can be determined together with the in-plane retardation Re, which is used to calculate the birefringence index An. In a

- 10 - case where the area of a cross section of a disperse phase for which the equivalent circle diameter is not less than 1 pm and not more than 10 pm has a proportion of not less than 1% and not more than 30%, the agricultural film can be stretched well sufficiently in the MD and have a high breaking strength in the MD. The above arrangement, in other words, allows production of an agricultural film having a high stretch at break in the MD.

[0020] In the present specification, the disperse phase refers to a phase constituted by individual particles dispersed in the continuous phase, and the equivalent circle diameter of the disperse phase refers to the equivalent circle diameter determined of an observed particle. The term "equivalent circle diameter" as used herein refers to the diameter of a circle having an area equal to the cross-sectional area of a particle shown in a captured cross section of a layer. The equivalent circle diameter may be determined from an image of a cross section of an agricultural film with use of an image analysis system.

[0021] The resin composition, of which the layer including a continuous phase and a disperse phase is made, may include a component for the continuous phase and a

“11 - component for the disperse phase at any mixing ratio. The mixing ratio may be selected as below.

[0022] With respect to 100 parts by mass of the combined amount of the component for the continuous phase and the component for the disperse phase, the component for the continuous phase is contained in an amount of preferably not less than 50 parts by mass, more preferably not less than 60 parts by mass, even more preferably not less than 65 parts by mass, particularly preferably not less than 70 parts by mass, and is contained in an amount of preferably not more than 98 parts by mass, more preferably not more than 95 parts by mass, even more preferably not more than 90 parts by mass, particularly preferably not more than 85 parts by mass.

[0023] With respect to 100 parts by mass of the combined amount of the component for the continuous phase and the component for the disperse phase, the component for the disperse phase is contained in an amount of preferably not less than 2 parts by mass, more preferably not less than 5 parts by mass, even more preferably not less than 10 parts by mass, particularly preferably not less than 15 parts by mass, and is contained in an amount of preferably not more than 50 parts by mass, more preferably not more

_ 12 - than 40 parts by mass, even more preferably not more than 35 parts by mass, particularly preferably not more than 30 parts by mass.

[0024] Continuous phase The continuous phase preferably includes a thermoplastic resin. Examples of the thermoplastic resin include an ethylene-based copolymer, a polyolefin-based resin, and a combination thereof.

[0025] Ethylene-based copolymer Examples of the ethylene-based copolymer include (i) an ethylene-vinylester copolymer, (ii) a copolymer of an ethylene and an unsaturated carboxylic acid and/or a derivative thereof (hereinafter referred to also as "ethylene- unsaturated carboxylic acid (derivative) copolymer"), and (iii) an ethylene-a-olefin copolymer. Only one ethylene- based copolymer may be used alone, or two or more kinds of ethylene-based copolymers may be used in combination.

[0026] The ethylene-vinylester copolymer is an ethylene- vinylester copolymer including, as main monomeric units, a monomeric unit derived from an ethylene and a monomeric unit derived from a vinylester. The ethylene- vinylester copolymer may be a random copolymer or block

_ 13 - copolymer of an ethylene monomer and a vinylester monomer.

[0027] Examples of the vinylester as a component of the ethylene-vinylester copolymer include a vinylester of a fatty acid having 2 to 4 carbon atoms. Specific examples include vinyl acetate and vinyl propionate. In accordance with an aspect of the present invention, the ethylene- vinylester copolymer includes monomeric units derived from of two or more kinds of vinylester. The ethylene- vinylester copolymer preferably includes vinyl acetate, in particular.

[0028] Specific examples of the ethylene-vinylester copolymer, which includes a monomeric unit derived from an ethylene and a monomeric unit derived from a vinylester, include an ethylene-vinyl acetate copolymer and an ethylene-vinyl propionate copolymer. The ethylene- vinylester copolymer is suitably an ethylene-vinyl acetate copolymer (EVA), in particular. Only one ethylene- vinylester copolymer may be used alone, or two or more kinds of ethylene-vinylester copolymers may be used in combination.

[0029] The ethylene-vinylester copolymer may include a

_ 14 - monomeric unit derived from a monomer other than an ethylene or a vinylester.

[0030] Examples of commercially available products usable as the ethylene-vinylester copolymer include Evatate (registered trademark) (available from Sumitomo Chemical Co., Ltd.), Sumitate (registered trademark) (available from Sumitomo Chemical Co., Ltd.), Novatec (registered trademark] EVA (available from Japan polyethylene Corporation), Ultrathene (registered trademark) (available from Tosoh Corporation), Suntec (registered trademark) EVA (Asahi Kasei Co., Ltd.), and Evaflex (registered trademark) (available from Du Pont-Mitsui Polychemicals Co., Ltd.).

[0031] The ethylene-vinylester copolymer includes a vinylester-derived monomeric unit in an amount of preferably not less than 7% by mass and not more than 30% by mass, more preferably not less than 10% by mass and not more than 28% by mass, even more preferably not less than 12% by mass and not more than 25% by mass.

[0032] The ethylene-vinylester copolymer includes an ethylene-derived monomeric unit in an amount of preferably not less than 70% by mass and not more than

- 15 - 93% by mass, more preferably not less than 72% by mass and not more than 90% by mass, even more preferably not less than 75% by mass and not more than 88% by mass.

[0033] In a case where two or more kinds of ethylene- vinylester copolymers are used in combination, the combination of the copolymers includes an ethylene- derived monomeric unit in an amount E calculated on the basis of the following formula (2): E (mass%) = (E1* Wi + Ea Wo +...4 En Wg) /(W1 + Wo +... Wn) (2) where m represents the number of kinds of ethylene- vinylester copolymers (namely, an ethylene-vinylester copolymer 1, an ethylene-vinylester copolymer 2,..., and an ethylene-vinylester copolymer m) used in combination (where m is an integer of not less than 3). Ex refers to the amount (mass%) of an ethylene-derived monomeric unit included in an ethylene-vinylester copolymer k, and Wx refers to the amount of the ethylene-vinylester copolymer k included in the resin composition (where k is an integer of 1 to m).

Similarly, in a case where two or more kinds of ethylene-vinylester copolymers are used in combination,

_ 16 - the combination of the copolymers includes a vinylester- derived monomeric unit in an amount E' calculated on the basis of the following formula (3): E' (mass%) = (E'1:Wi + E'2 Wo +...+ En Wn) / (Wi + Wo +... Wy) (3) where m represents the number of kinds of copolymers (namely, a copolymer 1, a copolymer 2,..., and a copolymer m) used in combination (where m is an integer of not less than 3). E' refers to the amount (mass%) of a vinylester-derived monomeric unit included in a copolymer k, and Wi refers to the amount of the copolymer k included in the resin composition (where k is an integer of 1 to mj. The respective amounts of the ethylene-derived monomeric unit and the vinylester-derived monomeric unit in the ethylene-vinylester copolymer can be determined by a saponification method. More specifically, in a case where the ethylene-based copolymer is an ethylene-vinyl acetate copolymer, the amounts can be determined in accordance with JIS K 7192:1999.

[0034] The ethylene-vinylester copolymer has a density that is not less than 925 kg/m?3, preferably not less than 930 kg/m?3, more preferably not less than 933 kg/m3, and that

-17 - is not more than 955 kg/ m3, preferably not more than 952 kg/m3, more preferably not more than 950 kg/ m3. In a case where the ethylene-vinylester copolymer has a density of not less than 925 kg/m? and not more than 955 kg/m3, and the disperse phase includes a component described later, the agricultural film scatters more light in summer (during which the air temperature reaches a temperature close to 40°C) and has a constant light transmittance at 40°C. The density of the ethylene-vinylester copolymer is a value measured at 23°C by Method A of JIS K 7112:1999.

[0035] In a case where two or more kinds of ethylene- vinylester copolymers are used in combination, the combination of the ethylene-vinylester copolymers has a density d that may be approximated on the basis of the following formula (4): d (kg/m?) = (di: Wi + do: Wo +...+ dm Wo) / (Wi + Wo +... Wn) (4) where m represents the number of kinds of ethylene- vinylester copolymers (namely, an ethylene-vinylester copolymer 1, an ethylene-vinylester copolymer 2,..., and an ethylene-vinylester copolymer m) used in combination (where m is an integer of not less than 3). dx refers to the

- 18 - density (unit: kg/m3) of an ethylene-vinylester copolymer k, and Wx refers to the amount (unit: kg) of the ethylene- vinylester copolymer k in the resin composition (where k is an integer of 1 to mj.

This indicates that in an aspect, the density d of the ethylene-vinylester copolymer included in the resin composition may be adjusted through the combined use of two or more kinds of ethylene-vinylester copolymers.

[0036] The ethylene-vinylester copolymer has a melt flow rate (MFR) of preferably not less than 0.05 g/10 minutes and not more than 20 g/10 minutes, more preferably not less than 0.1 g/10 minutes and not more than 15 g/10 minutes. The MFR is measured by Method A of JIS K 7210:1999 at 190°C under a load of 21.18 N.

[0037] The ethylene-unsaturated carboxylic acid (derivative) copolymer is an ethylene-unsaturated carboxylic acid (derivative) copolymer including, as main monomeric units, a monomeric unit derived from an ethylene and a monomeric unit derived from an unsaturated carboxylic acid and/or a derivative thereof. The ethylene-unsaturated carboxylic acid (derivative) copolymer may be a random copolymer or block copolymer of an ethylene monomer and an unsaturated carboxylic acid monomer and/or a

_ 19 - monomer of a derivative thereof.

[0038] Examples of the unsaturated carboxylic acid as a component of the ethylene-unsaturated carboxylic acid (derivative) copolymer include, but are not limited to, (i) an unsaturated monocarboxylic acid such as (methj)acrylic acid, crotonic acid, isocrotonic acid, and 3-butenoic acid and (ii) an unsaturated dicarboxylic acid such as maleic acid and fumaric acid. The unsaturated carboxylic acid is, in particular, preferably an unsaturated monocarboxylic acid, and is preferably (methjacrylic acid, for example. The present specification uses the term "(methjacrylic acid” to collectively refer to acrylic acid and methacrylic acid.

[0039] Examples of the derivative of the unsaturated carboxylic acid as a component of the ethylene- unsaturated carboxylic acid (derivative) copolymer include a salt of the above unsaturated carboxylic acid, an unsaturated carboxylic acid ester, an acid anhydride, an unsaturated carboxylic acid amide, and an unsaturated carboxylic acid imide. The derivative is preferably a salt of the unsaturated carboxylic acid or an unsaturated carboxylic acid ester. Examples of the salt of the unsaturated carboxylic acid include a sodium salt, potassium salt, calcium salt, and zinc sodium of the

_ 20 - unsaturated carboxylic acid. Examples of the unsaturated carboxylic acid ester include (i) an unsaturated carboxylic acid alkyl ester such as unsaturated carboxylic acid methyl ester, unsaturated carboxylic acid ethyl ester, and unsaturated carboxylic acid butyl ester, (ii) an unsaturated carboxylic acid aryl ester such as unsaturated carboxylic acid phenyl ester, and (iii) unsaturated carboxylic acid glycidyl ester.

[0040] Specific examples of the ethylene-unsaturated carboxylic acid (derivative) copolymer for the present invention including a monomeric unit derived from an ethylene and a monomeric unit derived from an unsaturated carboxylic acid and/or a derivative thereof include (i) an ethylene-unsaturated carboxylic acid copolymer such as an ethylene-{meth}acrylic acid copolymer, (ii) an ionomer produced by neutralizing part of all of the carboxyl groups of an ethylene-unsaturated carboxylic acid copolymer such as an ethylene- (meth)acrylic acid copolymer with use of an ion of a metal such as sodium, potassium, calcium, and zinc, and (iii) an ethylene-unsaturated carboxylic acid ester copolymer such as an ethylene-methyl (methjacrylate copolymer, an ethylene-ethyl (meth)acrylate copolymer, and an ethylene- butyl (meth)acrylate copolymer. The ethylene-unsaturated

-21 - carboxylic acid (derivative) copolymer is, in particular, suitably an ethylene-(meth}acrylic acid copolymer, an ethylene-methyl (methjacrylate copolymer, or an ethylene- ethyl (meth)acrylate copolymer, for example. In accordance with an aspect of the present invention, the ethylene- unsaturated carboxylic acid (derivative) copolymer may include monomeric units derived from two or more kinds of unsaturated carboxylic acids and/or derivatives thereof.

[0041] Specific examples of the ethylene-unsaturated carboxylic acid (derivative) copolymer include the following: (i) Ethylene-unsaturated carboxylic acid copolymer Nucrel (registered trademark) (ethylene-methacrylic acid copolymer available from Du Pont-Mitsui Polychemicals Co., Ltd.) (ii) Ionomer produced by neutralizing part or all of the carboxyl groups of an ethylene-unsaturated carboxylic acid copolymer with use of a metal ion Himilan (registered trademark) (ionomer produced by neutralizing part of the carboxyl groups of an ethylene- methacrylic acid copolymer with use of zinc ions or sodium ions, available from Du Pont-Mitsui Polychemicals Co., Ltd.) (iii) Ethylene-unsaturated carboxylic acid ester

_ 090 copolymer Acryft (registered trademark) (ethylene-methyl methacrylate copolymer available from Sumitomo Chemical Co., Ltd.}, Rexpearl (registered trademark) EMA (ethylene- methyl acrylate copolymer available from Japan polyethylene Corporation), Rexpearl (registered trademark) EEA (ethylene-ethyl acylate copolymer available from Japan polyethylene Corporation), Lotryl (registered trademark} (ethylene-methyl acrylate copolymer or ethylene-butyl acrylate copolymer available from Arkema Inc.}, and Elvaloy (registered trademark] AC (one of an ethylene-methyl acrylate copolymer, an ethylene-ethyl acylate copolymer, and an ethylene-butyl acrylate copolymer, available from DuPont)

[0042] Only one ethylene-unsaturated carboxylic acid (derivative) copolymer may be used alone, or two or more kinds of ethylene-unsaturated carboxylic acid (derivative) copolymers may be used in combination.

[0043] The ethylene-unsaturated carboxylic acid (derivative) copolymer includes a monomeric unit derived from an unsaturated carboxylic acid and/or a derivative thereof in an amount of, in view of a balance between the film rigidity and light scattering (haze value) at 40°C, preferably not

_ 23 - less than 10% by mass and not more than 40% by mass, more preferably not less than 15% by mass and not more than 35% by mass, even more preferably not less than 20% by mass and not more than 30% by mass, with respect to 100% by mass of the ethylene-unsaturated carboxylic acid (derivative) copolymer.

[0044] The amount of the monomeric unit derived from an unsaturated carboxylic acid and/or a derivative thereof in the ethylene-unsaturated carboxylic acid (derivative) copolymer may be measured by an infrared radiation absorption spectrum analysis method.

[0045] The ethylene-unsaturated carboxylic acid (derivative) copolymer includes a monomeric unit derived from an ethylene in an amount of, in view of a balance between the film rigidity and light scattering (haze value} at 40°C, preferably not less than 60% by mass and not more than 90% by mass, more preferably not less than 65% by mass and not more than 85% by mass, even more preferably not less than 70% by mass and not more than 80% by mass, with respect to 100% by mass of the ethylene-unsaturated carboxylic acid (derivative) copolymer.

[0046] The amount of the monomeric unit derived from an

_ 24 - ethylene in the ethylene-unsaturated carboxylic acid (derivative) copolymer may be calculated by subtracting the amount of the monomeric unit derived from an unsaturated carboxylic acid and/or a derivative thereof, which amount has been measured by an infrared radiation absorption spectrum analysis method, from 100% by mass.

[0047] In a case where two or more kinds of ethylene- unsaturated carboxylic acid (derivative) copolymers are used in combination, the combination of the ethylene- unsaturated carboxylic acid (derivative) copolymers includes an ethylene-derived monomeric unit in an amount E'' calculated on the basis of the following formula (5): E'" (mass%) = (E'1* W's + E24 Wo +...+ Em W/m) /(W1 + Wa +...W'n) (5) where m represents the number of kinds of ethylene- unsaturated carboxylic acid (derivative) copolymers (namely, an ethylene-unsaturated carboxylic acid (derivative) copolymer 1, an ethylene-unsaturated carboxylic acid (derivative) copolymer 2,..., and an ethylene-unsaturated carboxylic acid (derivative) copolymer m) used in combination (where m is an integer of not less

_ 05 than 2). E'' refers to the amount of an ethylene-derived monomeric unit in an ethylene-unsaturated carboxylic acid (derivative) copolymer k, and W' refers to the amount of the copolymer k included in the resin composition (where k is an integer of 1 to m).

[0048] The ethylene-unsaturated carboxylic acid (derivative) copolymer has a melt flow rate (MFR) of preferably not less than 0.1 g/10 minutes and not more than 10 g/10 minutes in view of processing the ethylene-unsaturated carboxylic acid (derivative) copolymer into a film. The MFR is measured by Method A of JIS K 7210:1999 at 190°C under a load of 21.18 N.

[0049] The ethylene-unsaturated carboxylic acid (derivative) copolymer has a density of not less than 930 kg/m? and not more than 950 kg/m3, preferably not less than 935 kg/m? and not more than 945 kg/m3, for increased light scattering in summer (during which the air temperature reaches a temperature close to 40°C). The density of the ethylene-unsaturated carboxylic acid (derivative) copolymer for the present invention is a value measured by a method defined in JIS K 6760-1981. A density of less than 930 kg/m? or more than 950 kg/m3 is not preferable, as such a density will make it difficult to achieve light scattering

_ 026 - (haze value} at a temperature around 40°C.

[0050] In a case where two or more kinds of ethylene- unsaturated carboxylic acid (derivative) copolymers are used in combination, the combination of the copolymers has a density d' calculated on the basis of the following formula (6): d' (kg/m?) = (di Wi + do Wo +...+ dm Wn)/(Wi1 + Wao +... Wig) (6) where m represents the number of kinds of ethylene- unsaturated carboxylic acid (derivative) copolymers (namely, an ethylene-unsaturated carboxylic acid (derivative) copolymer 1, an ethylene-unsaturated carboxylic acid (derivative) copolymer 2,..., and an ethylene-unsaturated carboxylic acid (derivative) copolymer m) used in combination (where m is an integer of not less than 2). d'x refers to the density (unit: kg/m3) of an ethylene-unsaturated carboxylic acid (derivative) copolymer k, and W' refers to the amount (unit: kg} of the ethylene- unsaturated carboxylic acid (derivative) copolymer k included in the resin composition (where k is an integer of 1 to m).

- 27 -

[0051] The ethylene-a-olefin copolymer is an ethylene-a- olefin copolymer including, as main monomeric units, a monomeric unit derived from an ethylene and a monomeric unit derived from an a-olefin. The ethylene-a-olefin copolymer may be a random copolymer or block copolymer of an ethylene monomer and an a-olefin monomer.

[0052] The a-olefin monomer preferably has 3 to 20 carbon atoms. Examples of the ethylene-a-olefin copolymer include an ethylene-propylene copolymer, an ethylene-1-butene copolymer, an ethylene-1-pentene copolymer, an ethylene- l-hexene copolymer, an ethylene-1-heptene copolymer, and ethylene-1-octene copolymer. The ethylene-a-olefin copolymer is, among others, particularly preferably an ethylene-1-butene copolymer, an ethylene-1-hexene copolymer, or an ethylene-1l-octene copolymer. The ethylene-a-olefin copolymer may be a copolymer of an ethylene and two or more kinds of a-olefins.

[0053] The ethylene-a-olefin copolymer contributes to provision of a strong film. The ethylene-a-olefin copolymer is, in order to produce a strong film, preferably produced by polymerizing an ethylene and an a-olefin with use of a metallocene catalyst.

- 28 -

[0054] Examples of commercially available products usable as the ethylene-a-olefin copolymer include: Excellen (registered trademark) FX (available from Sumitomo Chemical Co., Ltd.), Tafmer (registered trademark) (available from Mitsui Chemicals, Inc.), ENGAGE (registered trademark) (available from Dow Chemical), AFFINITY (registered trademark) (available from Dow Chemical), EXACT (registered trademark) (available from ExxonMobil), and Kernel (registered trademark} (available from Japan polyethylene Corporation).

[0055] Only one ethylene-a-olefin copolymer may be used alone, or two or more kinds of ethylene-a-olefin copolymers may be used in combination.

[0056] The ethylene-a-olefin copolymer has a density of not less than 860 kg/m? and not more than 895 kg/m3, preferably not less than 865 kg/m3 and not more than 890 kg/m?3, for increased light scattering in summer (during which the air temperature reaches a temperature close to 40°C). The density of the ethylene-a-olefin copolymer for the present invention is a value measured by a method defined in JIS K 6760-1981.

[0057]

- 29 - In a case where two or more kinds of ethylene-a- olefin copolymers are used in combination, the combination of the ethylene-a-olefin copolymers has a density d'' calculated on the basis of the following formula (7): d" (kg/m?) = di Wai + dz Wa ++ dm Win) /(W'y + W's +, W/m) (7) where m represents the number of kinds of ethylene- a-olefin copolymers (namely, an ethylene-a-olefin copolymer 1, an ethylene-a-olefin copolymer 2,..., and an ethylene-a-olefin copolymer m) used in combination (where m is an integer of not less than 2). dx refers to the density (unit: kg/m3) of an ethylene-a-olefin copolymer k, and Wx refers to the amount (unit: kg) of the ethylene-a-olefin copolymer k in the resin composition (where k is an integer of 1 to m).

[0058] The ethylene-a-olefin copolymer has a melt flow rate (MFR) of preferably not less than 0.05 g/10 minutes and not more than 20 g/10 minutes, more preferably not less than 0.1 g/10 minutes and not more than 15 g/10 minutes. The MFR is measured by Method A of JIS K

_ 30 - 7210:1999 at 190°C under a load of 21.18 N.

[0059] The continuous phase may include, in addition to a thermoplastic resin, at least one additive selected from a light stabilizer, an ultraviolet absorber, an anti-clouding agent, an antioxidant, an anti-fogging agent, and a lubricant, as long as such an additive does not prevent the present invention from being effective.

[0060] Disperse phase The disperse phase preferably includes at least one component selected from organic particles, inorganic particles, and a thermoplastic resin. The component included in the disperse phase may have any refractive index. The refractive index is preferably not less than 1.44 and not more than 1.65, more preferably not less than 1.49 and not more than 1.53.

[0061] Organic particles Examples of the organic particles include crosslinked acrylic particles. Examples of the crosslinked acrylic particles include (ij particles of a crosslinked copolymer of crosslinked (meth)acrylic acid ester and styrene (crosslinked MMA-St copolymer particles) and (ii) crosslinked polymethyl methacrylate particles (crosslinked

-31 - PMMA particles). Examples of the (meth)acrylic acid ester include methyl acrylate, ethyl acylate, butyl acrylate, methyl methacrylate, ethyl methacrylate, and butyl methacrylate. The (meth)acrylic acid ester is preferably methyl acrylate, methyl methacrylate, or butyl methacrylate, more preferably methyl methacrylate.

[0062] The particles of a crosslinked copolymer of (meth)acrylic acid ester and styrene may be (i) crosslinked copolymer particles consisting only of a monomeric unit derived from (methj}acrylic acid ester and a monomeric unit derived from styrene or (ii) crosslinked copolymer particles including a monomeric unit other than a monomeric unit derived from (meth)acrylic acid ester or a monomeric unit derived from styrene. The particles of a crosslinked copolymer of (methacrylic acid ester and styrene include a monomeric unit derived from (meth)acrylic acid ester and a monomeric unit derived from styrene at a combined proportion of preferably not less than 80% by mass with respect to all the monomeric units.

[0063] The particles of a crosslinked copolymer of (meth)acrylic acid ester and styrene include a monomeric unit derived from (methjacrylic acid ester in an amount of preferably 50% by mass to 99% by mass, more preferably

32 - 60% by mass to 90% by mass. The particles of a crosslinked copolymer of (meth)acrylic acid ester and styrene include a monomeric unit derived from styrene in an amount of preferably 1% by mass to 50% by mass, more preferably 10% by mass to 40% by mass. The above amounts assume that the combined amount of the monomeric unit derived from (methjacrylic acid ester and the monomeric unit derived from styrene is 100% by mass.

[0064] The particles of a crosslinked copolymer of (meth)acrylic acid ester and styrene may be produced by polymerizing (i) at least one kind of (methjacrylic acid ester, (ii) styrene, and as necessary (iii) a monomeric component including another monomer by a publicly known method such as suspension polymerization.

[0065] The crosslinked acrylic particles may be produced by, for example, suspension polymerization of a monomeric component together with a crosslinking agent. The crosslinking agent is preferably a compound having two or more unsaturated groups. Specific examples of the crosslinking agent include ethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, trimethylolpropanetrimethacrylate, and divinylbenzene.

[0066]

- 33 - The organic particles have a volume median diameter of preferably not less than 1 um, more preferably not less than 2 pm, even more preferably not less than 3 pm, for increased light scattering in summer (during which the air temperature reaches a temperature close to 40°C). The volume median diameter is preferably not more than 20 um, more preferably not more than 15 pm, even more preferably not more than 10 pm. The volume median diameter of the organic particles is measured by a Coulter counter method.

[0067] The organic particles have a refractive index of not less than 1.500 and not more than 1.515. The refractive index is a value measured at room temperature by a particle immersion method.

[0068] Examples of commercially available products of the organic particles include Techpolymer (registered trademark) MSX series (available from Sekisui Plastics Co., Ltd.), Techpolymer (registered trademark) SSX series (available from Sekisui Plastics Co., Ltd.), Art-pearl (registered trademark) G series (available from Negami Chemical Industrial Co., Ltd.), Art-pearl (registered trademark] GS series (available from Negami Chemical Industrial Co., Ltd}, and Ganzpearl (registered trademark)

- 34 - GSM series (available from Aica Kogyo Co., Ltd.).

[0069] Inorganic particles Examples of the inorganic particles include particles of glass, calcium carbonate, mica, kaolin, aluminosilicate (zeolite), and silica.

[0070] The glass particles are particles including silicon dioxide (SiO2}). The glass particles may include at least one kind of inorganic compound selected from the group consisting of boron oxide (B203}, aluminum oxide (Al203}, sodium oxide (Na20)}, calcium oxide (CaO), and zinc oxide (ZnO). The glass particles may further include another inorganic compound(s) and/or an additive(s) as necessary. Specifically, the above inorganic compound may as necessary be mixed as appropriate with a commonly used inorganic compound such as zirconium oxide, magnesium oxide, strontium oxide, lanthanum oxide, yttrium oxide, gadolinium oxide, bismuth oxide, antimony oxide, tantalum oxide, niobium oxide, tungsten oxide, magnesium carbonate, silicon nitride, aluminum nitride, aluminum oxynitride, magnesium fluoride, calcium fluoride, sodium fluoride, lithium fluoride, and iron for preparation of an agricultural film having a birefringence index within the above range.

_ 35 -

[0071] The inorganic particles may have any shape. The inorganic particles may have any of various shapes such as a spherical shape (for example, glass beads), a fibrous shape (for example, chopped or milled fibers), and a flake shape.

[0072] In a case where the inorganic particles have a spherical shape, the inorganic particles have a volume median diameter of preferably not less than 1 pm, more preferably not less than 2 pm, even more preferably not less than 3 pm, for increased light scattering in summer (during which the air temperature reaches a temperature close to 40°C). The volume median diameter is preferably not more than 20 pm, more preferably not more than 15 pm, even more preferably not more than 10 pm. The volume median diameter of the particles is measured by a laser diffraction method.

[0073] In a case where the inorganic particles have a fibrous shape, the inorganic particles may have any aspect ratio. The inorganic particles have an aspect ratio of 1 to 500, preferably 1 to 100, more preferably 1 to 50, for increased light scattering in summer (during which the air temperature reaches a temperature close to 40°C).

_ 36 -

[0074] The inorganic particles may be surface-treated with use of a surface treatment agent such as a coupling agent.

[0075] Thermoplastic resin Examples of the thermoplastic resin include (i} an uncrosslinked acrylic resin such as polymethyl methacrylate and a methyl methacrylate-phenyl methacrylate copolymer, (ii) a polyvinyl alcohol (PVOH), and (iii) a cyclic olefin copolymer (COC). The thermoplastic resin for the disperse phase differs from that for the continuous phase.

[0076] The disperse phase may include, in addition to at least one selected from organic particles, inorganic particles, and a thermoplastic resin, at least one additive selected from an infrared absorber, a light stabilizer, an ultraviolet absorber, an anti-clouding agent, an antioxidant, an anti-fogging agent, and a lubricant, as long as such an additive does not prevent the present invention from being effective.

[0077] Examples of the infrared absorber include a hydrotalcite compound and a lithium aluminum complex hydroxide. Specific examples of the hydrotalcite compound

37 - include natural hydrotalcite, DHT-4A (available from Kyowa Chemical Industry Co., Ltd.), Magclear (available from Toda Kogyo Corporation), MAGCELER (registered trademark) 1 (available from Kyowa Chemical Industry Co., Ltd.), and Stabiace (registered trademark) HT-P (Sakai Chemical Industry Co., Ltd.). Specific examples of the lithium aluminum complex hydroxide include OPTIMA-SS (available from Toda Kogyo Corporation) and Mizuka-rack (registered trademark) (Mizusawa Industrial Chemicals, Ltd.).

[0078] An embodiment of the present invention may use a hydrotalcite compound alone, a lithium aluminum complex hydroxide alone, or both in combination.

[0079] Examples of the light stabilizer include a hindered amine compound having a structure disclosed in Japanese Patent Application Publication, Tokukaihei, No. 8-73667. Specific examples include Tinuvin (registered trademark) 622 (available from BASF), Chimassorb (registered trademark) 944 (available from BASF), Chimassorb (registered trademark) 119 (available from BASF), Hostavin (registered trademark] N30 (available from Clariant), Hostavin (registered trademark} (available from Clariant}, Cyasorb (registered trademark) UV3529 (available from Cytec), and Cyasorb (registered trademark) UV3346

- 38 - (available from Cytec).

[0080] Other examples of the light stabilizer include a hindered amine compound having a structure disclosed in Japanese Patent Application Publication, Tokukaihei, No. 11-315067, Japanese Patent Application Publication, Tokukai, No. 2001-139821, WO 2005/082852, or Japanese Translation of PCT International Application, Tokuhyo, No. 2009-530428. Specific examples include NOR371 (available from BASF), Adekastab (registered trademark) LA-900 (available from Adeka Corporation), Adekastab (registered trademark) LA-81 (available from Adeka Corporation), and Hostavin (registered trademark) NOW (available from Clariant).

[0081] The light stabilizer can also be, for example, an ethylene-cyclic aminovinyl compound copolymer having a monomeric unit based on an ethylene and a monomeric unit based on a cyclic aminovinyl compound. Examples of the ethylene-cyclic aminovinyl compound copolymer include an ethylene-cyclic aminovinyl compound copolymer having a structure disclosed in Japanese Patent Application Publication, Tokukai, No. 2002-265693.

[0082] The light stabilizer is included in the resin

_ 30 - composition (of which the layer including a continuous phase and a disperse phase is made) in an amount of preferably 0.01% by mass to 3% by mass, more preferably

0.05% by mass to 2% by mass, particularly preferably 0.1% by mass to 1% by mass, with respect to 100% by mass of the resin composition.

[0083] Examples of the ultraviolet absorber include a 2- hydroxybenzophenone, a 2-(2’-hydroxyphenyl)benzotriazole, a benzoate, a substituted oxanilide, a cyanoacrylate, and a triazine.

[0084] Examples of the 2-hydroxybenzophenone include 2,4- dihydroxybenzophenone, 2-hydroxy-4- methoxybenzophenone, 2-hydroxy-4-octoxybenzophenone, and 5,5’ -methylenebis{2-hydroxy-4-methoxybenzophenonej.

[0085] Examples of the 2-(2’-hydroxyphenyljbenzotriazole include 2-(2’-hydroxy-5’-methylphenyljbenzotriazole, 2-(2’- hydroxy-3’,5’-di-tert-butylphenyl)benzotriazole, 2-(2- hydroxy-3’,5’-di-tert-butylphenyl)-5-chlorobenzotriazole, 2- (2’-hydroxy-3’-tert-butyl-5’-methylphenyl)-5- chlorobenzotriazole, 2-(2’-hydroxy-5’-tert- octylphenyl)benzotriazole, 2-(2’-hydroxy-37,5’- dicumylphenyl)benzotriazole, 2-(2-hydroxy-3,5-di-tert-

_ 40 - pentylphenyl)benzotriazole, 2,2’-methylenebis(4-tert-octyl- 6-benzotriazolyljphenol, and 2-(2’-hydroxy-3’-tert-butyl-5- carboxyphenyljbenzotriazole.

[0086] Examples of the benzoate include phenyl salicylate, resorcinol monobenzoate, 2,4-di-tert-butylphenyl-3’,5’-di- tert-butyl-4’-hydroxybenzoate, 2,4-di-tert-amylphenyl-35, 5’-di-tert-butyl-4’-hydroxybenzoate, and hexadecyl-3,5-di- tert-butyl-4-hydroxybenzoate.

[0087] Examples of the substituted oxanilide include 2- ethyl-2’-ethoxyoxanilide and 2-ethoxy-4’-dodecyloxanilide.

[0088] Examples of the cyanoacrylate include ethyl-a-cyano- B,B-diphenylacrylate and methyl-2-cyano-3-methyl-3-(p- methoxyphenyl)acrylate.

[0089] Examples of the triazine include 2-(4,6-diphenyl- 1,3,5-triazine-2-yl)-5-[(hexyl)joxy]-phenol, 2-[4,6-bis(2,4- dimethylphenyl)-1,3,5-triazine-2-yl]-5-(octyloxy)phenol, 2- (2-hydroxy-4-octoxyphenyl)-4,6-bis(2,4-di-tert- butylphenyl)-s-triazine, 2-(2-hydroxy--4-methoxyphenyl)- 4,6-diphenyl-s-triazine, and 2-(2-hydroxy--4-propoxy-5- methylphenyl)-4,6-bis(2,4-di-tert-butylphenyl)-s-triazine.

[0090]

- 41 - The ultraviolet absorber is preferably a 2-(2’- hydroxyphenyl)benzotriazole, more preferably 2-(2°- hydroxy-3’-tert-butyl-5’-methylphenyl)-5- chlorobenzotriazole or 2-(2-hydroxy-3,5-di-tert- pentylphenyl)benzotriazole.

[0091] Only one kind of ultraviolet absorber may be used alone, or two or more kinds of ultraviolet absorbers may be used in combination. The ultraviolet absorber is included in the resin composition (of which the layer including a continuous phase and a disperse phase is made} in an amount of preferably 0.001% by mass to 3% by mass, more preferably 0.005% by mass to 1% by mass, with respect to 100% by mass of the resin composition.

[0092] Examples of the anti-clouding agent include (i) a sorbitan-based surfactant such as a sorbitan fatty acid ester (for example, sorbitan monopalmitate, sorbitan monostearate, sorbitan monopalmitate, sorbitan monomontanate, sorbitan monooleate, and sorbitan dioleate) and an alkylene oxide adduct thereof, (ii) a glycerin-based surfactant such as a glycerin fatty acid ester (for example, glycerin monopalmitate, glycerin monostearate, diglycerin distearate, triglycerin monostearate, tetraglycerin dimontanate, glycerin

_ 402 - monooleate, diglycerin monooleate, diglycerin sesquioleate, tetraglycerin monooleate, hexaglycerin monooleate, hexaglycerin trioleate, tetraglycerin trioleate, tetraglycerin monolaurate, and hexaglycerin monolaurate), and an alkylene oxide adduct thereof, (iii) a polyethyleneglycol- based surfactant such as polyethyleneglycol monopalmitate and polyethyleneglycol monostearate, (iv) an alkylene oxide adduct of an alkyl phenol, (v)] an ester of a sorbitan /glycerine condensate and an organic acid, and (vi) a nonionic surfactant such as a polyoxyethylene alkylamine (for example, polyoxyethylene (2 mol) stearylamine, polyoxyethylene (4 mol) stearylamine, polyoxyethylene (2 mol) stearylamine monostearate, and polyoxyethylene (4 mol) laurylamine monostearate), and a fatty acid ester thereof. Only one anti-clouding agent may be used alone, or two or more kinds of anti-clouding agents may be used in combination.

[0093] Examples of the antioxidant include (i) a hindered phenol-based compound such as a 2,6-dialkylphenol derivative and a 2-alkylphenol derivative and (ii) a phosphorus-based ester compound having a trivalent phosphorus atom such as a phosphite-based compound and a phosphonite-based compound. Only one antioxidant may be used alone, or two or more kinds of antioxidants

- 43 - may be used in combination. The antioxidant is preferably a combination of a hindered phenol-based compound and a phosphorus-based ester compound for hue stabilization in particular.

[0094] Examples of the anti-fogging agent include (i) a fluorine compound having, for example, a perfluoroalkyl group or a w-hydrofluoroalkyl group (in particular, a fluorine-based surfactant) and (ii) a silicone-based compound having an alkylsiloxane group (in particular, a silicone-based surfactant). Specific examples of the fluorine-based surfactant include Unidyne (registered trademark) DSN-403N, DS-403, DS-406, and DS-401 (product names) available from Daikin Industries, Ltd. and Surflon (registered trademark) KC-40, AF-1000, and AF- 2000 (product names) available from AGC Seimi Chemical Co., Ltd. Examples of the silicone-based surfactant include SH-3746 (product name) available from Dow Corning Toray Co., Ltd. Only one anti-fogging agent may be used alone, or two or more kinds of anti-fogging agents may be used in combination. The anti-fogging agent is included in the resin composition (of which the layer including a continuous phase and a disperse phase is made} in an amount of preferably 0.01% by mass to 3% by mass, more preferably 0.02% by mass to 2% by mass, particularly

- 44 - preferably 0.05% by mass to 1% by mass, with respect to 100% by mass of the resin composition.

[0095] Other layers An agricultural film in accordance with an embodiment of the present invention may be (i) a film consisting only of a layer including a continuous phase and a disperse phase or (ii) a film including a layer(s) other than a layer including a continuous phase and a disperse phase. A film in accordance with a preferable embodiment of the present invention is a multilayer film that includes (i) an intermediate layer including a continuous phase and a disperse phase and (ii) two polyolefin-based resin layers sandwiching the intermediate layer. This layer structure advantageously increases the film strength.

[0096] The two polyolefin-based resin layers in the multilayer film may be identical to or different from each other. Specific examples of the structure of the multilayer film include three layers with two kinds, three layers with three kinds, four layers with three kinds, four layers with four kinds, five layers with four kinds, and five layers with five kinds.

[0097] In a case where the multilayer film includes layers

- 45 - with four or more kinds, the multilayer film may include a layer different from (i) a layer including a continuous phase and a disperse phase or (ii) a polyolefin-based resin layer, or may include three or more polyolefin-based resin layers. The multilayer film may include two or more layers each including a continuous phase and a disperse phase.

[0098] In a case where, for instance, a polyolefin-based agricultural film includes five layers, the agricultural film may have, for example, any of the following structures: C/A/B/A/C, A/B/A/C/C, A/A/B/A/A, A/A/B/B/A, and A/B/A/B/A, where A represents a polyolefin-based resin layer, B represents an intermediate layer including a continuous phase and a disperse phase, and C represents a layer different from A or B.

[0099] In a case where a film in accordance with an embodiment of the present invention is a multilayer film including three layers, the individual layers have a thickness ratio of preferably 1/2/1 to 1/4/1 (polyolefin- based resin layer / layer including a continuous phase and a disperse phase / polyolefin-based resin layer) in view of a balance between (i) light scattering and light transmittance at temperatures close to 40°C and (ii) the film strength.

_ 46 -

[0100] The polyolefin-based resin layer contains a polyolefin-based resin. Examples of the polyolefin-based resin include (i) a high pressure low density polyethylene, (ii) a high-density polyethylene, (iii) an ethylene-based copolymer such as an ethylene-1-butene copolymer and an ethylene-1-hexene copolymer, and (iv) an ethylene- unsaturated carboxylic acid ester copolymer such as an ethylene-methyl acrylate copolymer and an ethylene-methyl methacrylate copolymer. Only one polyolefin-based resin may be used alone, or two or more kinds of polyolefin- based resins may be used in combination.

[0101] The polyolefin-based resin layer may as necessary contain, for example, a light stabilizer, an ultraviolet absorber, an anti-clouding agent, an antioxidant, an anti- fogging agent, a lubricant, an anti-blocking agent, an antistatic agent, and/or a pigment. The polyolefin-based resin layer is distinguishable from the layer made of the resin composition in that the polyolefin-based resin layer does not contain a combination of predetermined glass particles and a predetermined ethylene-based copolymer.

[0102] A film in accordance with an embodiment of the present invention may include an anti-clouding coating

_ 47 - film layer on one or both surfaces thereof. Examples of the anti-clouding coating film layer include an anti-clouding layer made of an inorganic colloid and an anti-clouding coating film layer containing an inorganic colloid and a binder resin.

[0103] An inorganic colloid imparts hydrophilicity to a surface of a polyolefin-based resin film. An inorganic colloid is typically used in the form of a sol including a liquid dispersion medium such as water and the inorganic colloid dispersed therein. Specific examples of the sol include a silica sol and an alumina sol, preferably a silica sol.

[0104] Examples of the binder resin include a polyurethane- based resin, an acryl-based resin, an acryl-modified polyurethane-based resin, a polyester-based resin, and an epoxy-based resin.

[0105] The binder resin is typically used in the form of a water-based emulsion including (i) water or a mixed solvent of water and an aqueous solvent such as an alcohol and (ii) the binder resin dispersed in the mixed solvent.

[0106] The anti-clouding coating film layer is preferably an

- 48 - anti-clouding layer containing silica and a binder resin. The binder resin is preferably a polyurethane-based resin, an acryl-based resin, or an acryl-modified polyurethane- based resin.

[0107] The silica is preferably in the form of, for example, spheres having an average particle diameter of 5 nm to 100 nm.

[0108] With respect to 100% by mass of the combined amount of the silica and binder resin in the anti-clouding coating film layer, the anti-clouding coating film layer preferably contains the silica in an amount of 30% by mass to 70% by mass and the binder resin in an amount of 30% by mass to 70% by mass, more preferably contains the silica in an amount of 50% by mass to 65% by mass and the binder resin in an amount of 35% by mass to 50% by mass. An excessively small content of silica will result in an insufficient anti-clouding effect. An excessively large content of silica will cause the coating film to be clouded and may result in a decrease in the light transmittance at low temperatures.

[0109] An anti-clouding coating film layer containing silica and a binder resin may be formed as follows, for example:

- 49 - First, (i) a water-based emulsion containing a binder resin, (ii) an aqueous silica sol containing silica, and (iii] water as a dispersion medium are mixed with one another and stirred to prepare a coating solution. Next, the coating solution is applied to a surface by a publicly known means. The applied coating solution is dried. This allows an anti- clouding layer to be formed. Specific examples of the applying means include bar coating, gravure coating, reverse coating, brush coating, spray coating, kiss coating, die coating, and dipping. Examples of the drying means include hot air drying.

[0110] The coating film including silica and a binder resin has a thickness of preferably 0.3 pm to 1.5 pm, more preferably 0.5 um to 1.2 pm.

[0111] The coating solution may contain a silicone-based surfactant or a fluorine-based surfactant for increased coating easiness. Examples of the silicone-based surfactant include polyether-modified silicone oil.

[0112] The coating solution may as necessary include a crosslinking agent, a light stabilizer, and/or an ultraviolet absorber.

[0113]

- 50 - The anti-clouding coating film layer may be present on one or both surfaces of the film. The anti-clouding layer may be a single-layer film or a multilayer film including two or more layers.

[0114] Method for producing agricultural film A method for producing an agricultural film of an embodiment of the present invention preferably includes a film producing step of producing a film from a resin composition by an inflation method. The resin composition, of which the layer including a continuous phase and a disperse phase is made, is as described above under "Agricultural film".

[0115] A method for producing an agricultural film of an embodiment of the present invention may further include a mixing step of mixing a resin composition before the film producing step.

[0116] The resin composition may be mixed in, for example, a mixer such as a ribbon blender, a Banbury mixer, a Super Mixer, or a twin screw kneading extruder.

[0117] The extrusion temperature is preferably not lower than 130°C and not higher than 200°C, more preferably not

-51 - lower than 140°C and not higher than 180°C. The term "extrusion temperature” as used herein refers to the temperature of each of (iJ respective extruders for a layer including a continuous phase and a disperse phase and a layer(s} other than the layer including a continuous phase and a disperse phase and (ii) a die.

[0118] Adjusting, for example, the BUR and/or take-off speed as appropriate and producing a film from a resin composition by an inflation method during the film producing step allows production of an agricultural film having a birefringence index An of not more than 1.15 x 10-

3. In a case where the birefringence index An is more than

1.15 x 10-3, increasing the BUR and decreasing the take-off speed will reduce the birefringence index An. The term "BUR", also called blow ratio or blow-up ratio, refers to the ratio of the TD width of a film having been cut open to the circumference of a die.

[0119] Agricultural and horticultural facility An agricultural film in accordance with an embodiment of the present invention can, when the agricultural film is spread out in an agricultural and horticultural facility, suitably avoid being caught and broken by, for example, an agricultural and horticultural

- 52 - facility frame for spreading out the agricultural film in the agricultural and horticultural facility. The agricultural film is thus very easy to handle. The present invention also covers in its scope (i) a method for spreading out an agricultural film in accordance with an embodiment of the present invention in an agricultural and horticultural facility and (ii) an agricultural and horticultural facility in which such an agricultural film has been spread out.

[0120] An agricultural and horticultural facility covered by an agricultural film in accordance with an embodiment of the present invention can, since the film scatters a large amount of light in summer (during which the air temperature reaches a temperature close to 40°C), prevent damage such as leaf scorch of crop caused by excessive direct light. The agricultural and horticultural facility is suitably used for cultivation of, for example, spinach, tomatoes, leeks, cucumbers, and strawberries.

[0121] Examples of the agricultural and horticultural facility provided with an agricultural film in accordance with an embodiment of the present invention include a greenhouse and tunnel for plant cultivation. In the agricultural and horticultural facility, the agricultural film is spread out on, for example, an agricultural and

- 53 - horticultural facility frame. Examples

[0122] The description below deals with Examples of an embodiment of the present invention. The Examples and Comparative Examples involved tests conducted as below.

[0123] Test method Birefringence index The birefringence index An was measured by the method below at five random positions of a film. The average of the five values was used as the birefringence index of the film. A phase difference measuring device (KOBRA-WPR, available from Oji Scientific Instruments] was used to determine the respective directions of the slow axis and the fast axis of the film and the in-plane retardation Re of the film at a wavelength of 586 nm. The birefringence index An was calculated on the basis of the formula below.

[0124] An (birefringence index) = Re / d {overall thickness)

[0125] Proportion of the area of a cross section of a disperse phase for which the equivalent circle diameter is not less than 1 pm and not more than 10 pm to the area of a cross

- 54 - section of an intermediate layer The film was cut in a direction perpendicular to the film surface and parallel to the slow axis in the film plane, the direction of which slow axis was determined with use of the phase difference measuring device. An optical microscope (ECLIPSE (registered trademark) LV100DA-U, available from Nikon Corporation) was used to obtain images of two random positions on a cross section of the film at an observation magnification of 500. Each cross- sectional image of the film had an actual length of 238 pm in a direction parallel to the slow axis for the Examples described later.

[0126] Next, an image analysis system (LUZEX (registered trademark)-APPLICATION, available from Nireco Corporation) was used to determine the proportion of the area of a cross section of a disperse phase for which the equivalent circle diameter was not less than 1 pm and not more than 10 pm (hereinafter referred to also as the proportion of a disperse phase having an equivalent circle diameter of not less than 1 pm and not more than 10 um) relative to the area of a cross section of the intermediate layer in a cross-sectional image of the film. The proportion of a disperse phase for which the equivalent circle diameter was not less than 1 pm and not more than 10 pm was

_ 55 - determined for a cross-sectional image of each of two positions. The average of the two values was used as the proportion of a disperse phase having an equivalent circle diameter of not less than 1 pm and not more than 10 1m for the film.

[0127] Haze value A temperature controlled haze meter (THM-150TL, available from Murakami Color Research Laboratory Co., Ltd) was used for measurement at 40°C. The measurement conditions other than temperature were in conformity to JIS K 7136:2000.

[0128] Stretch at break in the MD AGS-100B (available from Shimadzu Corporation) was used for measurement at 23°C and a pulling speed of 500 mm/min. The measurement conditions other than those were in conformity to JIS K 6732-1981. Materials The description below shows the materials used.

[0129] The MFR below was measured by Method A of JIS K 7210:1999 at 190°C under a load of 21.18 N. Ethylene-based copolymer (1) Ethylene-vinyl acetate copolymer (EVA)

_ 56 - (hereinafter referred to as "EVA-1") Density: 952 kg/m? MFR (190°C, 21.18 N): 7 g/10 min Content of a monomeric unit derived from an ethylene: 72% by mass, content of a monomeric unit derived from vinyl acetate (VA): 28% by mass (with respect to 100% by mass of EVA-1) (Sumitate (registered trademark) KA-30, available from Sumitomo Chemical Co., Ltd.) (2) Ethylene-vinyl acetate copolymer (EVA) (hereinafter referred to as "EVA-2") Density: 935 kg/m} MFR (190°C, 21.18 N): 1.5 g/10 min Content of a monomeric unit derived from an ethylene: 85% by mass, content of a monomeric unit derived from vinyl acetate (VA): 15% by mass (with respect to 100% by mass of EVA-2) (Evatate (registered trademark) H2020, available from Sumitomo Chemical Co., Ltd.) (3) Ethylene-1-octene copolymer (POE) (hereinafter referred to as "POE-1") Density: 890 kg/m? MFR (190°C, 21.18 Nj): 1 g/10 min (ENGAGE (registered trademark) 8003: available from Dow Chemical)

_ 57 - Polyolefin-based resin (1) Polyethylene resin (PE (EPPE)) (hereinafter referred to as "PE-1") Density: 912 kg/m? MFR (190°C, 21.18 N}: 0.5 g/10 min Excellen (registered trademark) GMH GHO030, available from Sumitomo Chemical Co., Ltd. (2) Linear-chain low-density polyethylene resin (LLDPE) (hereinafter referred to as "PE-2") (3) Polyethylene resin (PE (EPPE)} (hereinafter referred to as "PE-3") Density: 921 kg/m? MFR (190°C, 21.18 N): 0.4 g/10 min Excellen (registered trademark) GMH GHOS1, available from Sumitomo Chemical Co., Ltd.

Particles (1) Crosslinked methyl methacrylate-styrene copolymer particles (hereinafter referred to as "particles- 1") Volume median diameter = 5 pm Refractive index (23°C) = 1.51 Techpolymer (registered trademark] MSX-5Z, available from Sekisui Plastics Co., Ltd. (2) Calcium carbonate (hereinafter referred to as "particles-2")

- 58 - (3) OMicron (registered trademark) NP5-PO (glass beads available from Sovitec} (hereinafter referred to as "particles-3") Volume median diameter = 5 pm Refractive index (23°C) = 1.51 Respective films of Examples 1 to 5 and Comparative Examples 1 to 5 were produced each of which included a structure of polyolefin-based resin layer / resin composition layer / polyolefin-based resin layer, and were evaluated.

[0130] [Example 1] Preparing masterbatch First, 49.2% by mass of EVA-2, 50% by mass of particles-1, and 0.8% by mass of Irganox (registered trademark) 1010 (antioxidant available from BASF) were fed into an intensive mixer (available from Nippon Roll MFG. Co., Ltd.) with respect to 100% by mass of a masterbatch to be produced. The ingredients were mixed with one another at 160°C for 5 minutes. The resulting mixture was fed into a single-screw extruder having a screw diameter of 65 mm (available from Japan Steel Works, Ltd.}), and was extruded therefrom to be pelletized. This produced a masterbatch for a resin composition for use as an intermediate layer. This masterbatch was labeled

- 50 - as MB-1.

[0131] Preparing film A three-layer inflation film forming device (available from Placo Co., Ltd.) including an inner-layer extruder (40- mm extruder), an intermediate-layer extruder (40-mm extruder), an outer-layer extruder (40-mm extruder), and a die having a diameter of 100 mm (with a lip gap of 1.2 mm) was used to form a three-layer tube-shaped film.

[0132] Specifically, a material of a polyolefin-based resin composition for an outer layer was fed into the outer-layer extruder. Materials of a resin composition for Example 1 were fed into the intermediate-layer extruder. A material of a polyolefin-based resin composition for an inner layer was fed into the inner-layer extruder. The materials in the extruders were melted and kneaded. After that, the amount of a product discharged from the die having a diameter of 100 mm was adjusted so that the inner layer would be 20 pm thick, the intermediate layer would be 60 pm thick, and the outer layer would be 20 pm thick (with the overall thickness of 100 pm). The melted resin composition for each layer was extruded. The extruded product was cooled to provide a three-layer tube-shaped film. The film was cut open at a BUR of 2.1, and was taken off at a take-off speed

- 60 - of 4.1 m/min. This produced a three-layer film. During this operation, the respective extruders for the inner layer, the intermediate layer, and the outer layer and the die each had a temperature of 140°C.

[0133] The material of the polyolefin-based resin composition for the outer layer was 100% by mass of PE-1. The materials of the resin composition for the intermediate layer of Example 1 were 30% by mass of EVA-1, 40% by mass of EVA-2, and 30% by mass of MB-1. The material of the polyolefin-based resin composition for the inner layer was similar that of the polyolefin-based resin composition for the outer layer.

[0134] Table 1 shows the birefringence index, the proportion of a disperse phase having an equivalent circle diameter of not less than 1 pm and not more than 10 1m, the haze value at 40°C, and the stretch at break in the MD of the film produced.

[0135] [Example 2] Resin compositions and a film were produced as in Example 1 except that the respective extruders for an inner layer, an intermediate layer, and an outer layer and the die each had a temperature of 150°C. Table 1 shows the

-61 - birefringence index, the proportion of a disperse phase having an equivalent circle diameter of not less than 1 pm and not more than 10 pm, the haze value at 40°C, and the stretch at break in the MD of the film produced.

[0136] [Example 3] Resin compositions and a film were produced as in Example 1 except that the take-off speed was 4.2 m/min and that the respective extruders for an inner layer, an intermediate layer, and an outer layer and the die each had a temperature of 160°C. Table 1 shows the birefringence index, the proportion of a disperse phase having an equivalent circle diameter of not less than 1 pm and not more than 10 pm, the haze value at 40°C, and the stretch at break in the MD of the film produced.

[0137] [Example 4] Masterbatch A masterbatch was used that included 40% by mass of PE-2 and 60% by mass of calcium carbonate. This masterbatch was labeled as MB-2.

[0138] Preparing film Materials of a polyolefin-based resin composition for an outer layer were 50% by mass of PE-1 and 50% by mass

- 62 - of PE-3. Materials of a resin composition for an intermediate layer of Example 4 were 92% by mass of PE-1 and 8% by mass of MB-2. Materials of a polyolefin-based resin composition for an inner layer were similar those of the polyolefin-based resin composition for the outer layer. Resin compositions and a film were produced as in Example 2 except for the above.

[0139] Table 1 shows the birefringence index, the proportion of a disperse phase having an equivalent circle diameter of not less than 1 pm and not more than 10 pm, the haze value at 40°C, and the stretch at break in the MD of the film produced.

[0140] [Example 5] Preparing masterbatch First, 49.2% by mass of EVA-2, 50% by mass of particles-3, and 0.8% by mass of Irganox (registered trademark) 1010 (antioxidant available from BASF) were fed into an intensive mixer (available from Japan Roller Producer} with respect to 100% by mass of a masterbatch to be produced. The ingredients were mixed with one another at 160°C for 5 minutes. The resulting mixture was fed into a single-screw extruder having a screw diameter of 65 mm (available from Japan Steel Works, Ltd.), and was

- 63 - extruded therefrom to be pelletized. This produced a masterbatch for a resin composition for use as an intermediate layer. This masterbatch was labeled as MB-3.

[0141] S Preparing film Materials of a resin composition for an intermediate layer of Example 5 were 10% by mass of EVA-2, 40% by mass of POE-1, and 50% by mass of MB-3. Resin compositions and a film were produced as in Example 4 except for the above.

[0142] Table 1 shows the birefringence index, the proportion of a disperse phase having an equivalent circle diameter of not less than 1 pm and not more than 10 pm, the haze value at 40°C, and the stretch at break in the MD of the film produced.

[0143] [Comparative Example 1] Resin compositions and a film were produced as in Example 1 except that the BUR was 1.4 and that the take- off speed was 6.4 m/min. Table 1 shows the birefringence index, the proportion of a disperse phase having an equivalent circle diameter of not less than 1 pm and not more than 10 pm, the haze value at 40°C, and the stretch at break in the MD of the film produced.

64 -

[0144] [Comparative Example 2] Resin compositions and a film were produced as in Example 2 except that the BUR was 1.4 and that the take- off speed was 6.4 m/min. Table 1 shows the birefringence index, the proportion of a disperse phase having an equivalent circle diameter of not less than 1 pm and not more than 10 pm, the haze value at 40°C, and the stretch at break in the MD of the film produced.

[0145] [Comparative Example 3] Resin compositions and a film were produced as in Example 1 except that the BUR was 1.4 and that the take- off speed was 6.3 m/min. Table 1 shows the birefringence index, the proportion of a disperse phase having an equivalent circle diameter of not less than 1 pm and not more than 10 pm, the haze value at 40°C, and the stretch at break in the MD of the film produced.

[0146] [Comparative Example 4] Resin compositions and a film were produced as in Example 4 except that the BUR was 1.4 and that the take- off speed was 6.1 m/min. Table 1 shows the birefringence index, the proportion of a disperse phase having an equivalent circle diameter of not less than 1 pm and not

- 65 - more than 10 pm, the haze value at 40°C, and the stretch at break in the MD of the film produced.

[0147] [Comparative Example 5] Resin compositions and a film were produced as in Example 5 except that the BUR was 1.4 and that the take- off speed was 6.4 m/min. Table 1 shows the birefringence index, the proportion of a disperse phase having an equivalent circle diameter of not less than 1 pm and not more than 10 pm, the haze value at 40°C, and the stretch at break in the MD of the film produced.

[Table 1] rr rr rr 0000 or or 0 Examples 00 = Comparative Examples | rrr rr rr prs | 2 3 [ 4 [ 5 | + [a [ 5 | a4 J 5 |] Name Classification Comonomer Density e DO deme) LL LL

_ © (mass%}

= | 39 | 30 | 30 | LL so [ so | so |L 02 B Mase 54.8 | 54.8 | 548 [ | 346 | 548 | 548 [ 548 | ~~] 3406 | Sg 5 (Grose [PE (EP) Te Jg LLL ee LLL EL ez |L Bo [LLDPE Jiippe [OO [- rr rr ree rae |] en rr rr | 4 LL 4 | oe + diameter {nm)

55 Sz [15 | 15 | 15 | TL Las [1 | 5 JL

“ carbonate %

rrr [es |] a5 | | Name | Classification [| Other —_ - - - E omer B Teeter Ter Tr Tero] Inner layer [Name | Classification | Density (kg/m) LL 1 ro | © 0 1 outer lay- er composit GBOS1 PE {EPPE) 921 Mass 50 50 50 50 ions © | meme LE LE LE Te Te | Te Te tion tion tion tion tion tion tion tion tion tion 2 Ter 2 fey J oer J ta De [24 | 44 | 2.4 | n not less than 1 pm and not more than 10 um

- 67 - Industrial Applicability

[0148] An agricultural film in accordance with an embodiment of the present invention is suitably usable as, for example, a covering material in an agricultural and horticultural facility such as a greenhouse for plant cultivation and a tunnel.

Claims

68 NL 2 023 910 CONCLUSIONS

An agricultural film, comprising: at least one layer comprising a continuous phase and a disperse phase, the agricultural film conforming to (A) and (B) below, (A) in a cross-section of the agricultural film, which cross-section is taken along a direction perpendicular to a surface of the agricultural film and parallel to a slow axis in a plane of the agricultural film, has a cross-sectional area of a portion of the disperse phase, for which portion an equivalent circle diameter is not less than 1 µm and not greater than 10 µm, a proportion of not less than 1% and not more than 30% with respect to a cross-sectional area of the at least one layer, and (B) the agricultural film has a birefringence index An of not more than 1, 15 x 10-3,

The agricultural film of claim 1, wherein the continuous phase comprises a thermoplastic resin.

The agricultural film of claim 1, wherein the continuous phase comprises a polyolefin-based resin.

The agricultural film of claim 1, wherein the continuous phase comprises a copolymer based on ethylene.

An agricultural film according to any one of claims 1 to 4, wherein the disperse phase comprises a component having a refractive index of not less than 1.44 and not more than 1.65.

An agricultural and horticultural facility, comprising: an agricultural and horticultural facility frame; and an agricultural film according to any one of claims 1 to 5, the agricultural film is spread on the frame of the agricultural and horticultural facility.