JP6716305B2 - Agricultural multilayer film - Google Patents

Description

The present invention relates to an agricultural multilayer film.

Conventionally, in the field of agriculture, when cultivating agricultural crops, in order to enhance marketability and productivity, vinyl chloride film, special films mainly composed of polyethylene, ethylene-vinyl acetate copolymer and polyolefin resin, etc. House cultivation and tunnel cultivation, in which useful crops are cultivated by being covered with the agricultural film, are being actively used.

In the above-mentioned greenhouse cultivation, leaf burning phenomenon is known as a high temperature disorder especially in summer. The leaf-burn phenomenon means that a large amount of direct rays enter the house and the leaves of the cultivated product are exposed to strong light and the leaves are burned. As a measure for preventing the leaf burn, there is a method of coloring the house with titanium oxide or the like to reduce the amount of direct light rays, but in that case, the total light transmittance also decreases. If the total light transmittance decreases, the penetration of sunlight into the house decreases, which adversely affects the cultivation of the crop itself. Adjusting the balance of the transmission and scattering of sun rays into such a house, suppressing leaf burns of the cultivated product without excessively reducing the total light transmittance, suggesting an agricultural film suitable for cultivation of crops There is Patent Document 1 as such. Patent Document 1 specifically discloses that mica is added to a polyolefin-based resin film that constitutes an agricultural film.

Further, there is a problem that an agricultural film used for greenhouse cultivation or the like is prone to deterioration because it is exposed to sunlight or the like outdoors for a long period of time and is damaged if it does not have sufficient weather resistance.

Further, there is a problem that when the above-mentioned agricultural film used for greenhouse cultivation or the like transmits ultraviolet rays, the inside of the greenhouse or the like is irradiated with ultraviolet rays, and the ultraviolet rays cause pests to gather and damage crops. Further, even when the lighting is turned on inside the house or the like at night, there is a problem that harmful insects gather due to the ultraviolet rays emitted from the lighting and leaking, and the crops are damaged.

As an agricultural film in which such a problem is solved, a triazine-based ultraviolet absorber containing a 3% or more inorganic compound containing a specific atom such as Si in all layers of a multilayer film having 3 or more layers, And a benzotriazole-based ultraviolet absorber have been proposed as an agricultural multilayer film (see Patent Document 2). The agricultural multilayer film has the above-mentioned configuration to suppress the transmission of ultraviolet rays and to suppress the bleed-out of the ultraviolet absorbent (see [0011] of Patent Document 2).

Patent No. 5638901 Japanese Patent No. 4279573

However, the above-mentioned agricultural film has not been sufficiently studied on the layer structure containing the ultraviolet absorber. In the above-mentioned agricultural film, the triazine-based UV absorber and the benzotriazole-based UV absorber are used by being contained in the same layer, and this is because the concentration of the UV absorber increases in the same layer. Due to the extrusion effect, the benzotriazole-based ultraviolet absorber, which easily bleeds out, is extruded out of the layer, and there is a problem that the long-term sustainability of the ultraviolet suppression effect is poor. In particular, since the benzotriazole-based ultraviolet absorber has a wide wavelength range of ultraviolet rays that can be cut, it is difficult for the above-mentioned agricultural film to maintain a wide cut area for ultraviolet rays for a long period of time.

In addition, the above-mentioned agricultural film has not been sufficiently examined for weather resistance. In conventional agricultural films, a light stabilizer is used to impart weather resistance. The light stabilizer is a fast-acting/highly deactivating NH type and a lagging/low-deactivating NR. Types and NOR types exist. The agricultural multilayer film has a problem that weather resistance is inferior in long-term sustainability when a lagging/low-deactivation type NR type or NOR type light stabilizer is not contained outside the house or the like. Further, in recent years, with the aging of agricultural workers, there is a tendency to continue to use the same film for as long as possible due to the time and effort involved in reworking agricultural films and economical problems. In that case, not only the durability of the film but also the continuation of the function (ultraviolet ray blocking effect) is required more than ever.

The present invention has been made in view of the above problems, an effect of suppressing leaf burn of a cultivated product while sufficiently ensuring a total light transmittance, an effect of suppressing ultraviolet rays in a wide range of wavelength region, and an ultraviolet ray. It is an object of the present invention to provide an agricultural multilayer film which is excellent in long-term sustainability of suppressive effect and weather resistance.

As a result of intensive studies to achieve the above object, the present inventors have identified A layer, B layer and C layer in an agricultural multilayer film in which A layer, B layer and C layer are laminated in this order. It has been found that the above object can be achieved when the composition is composed of components, and the present invention has been completed.

That is, the present invention relates to the following agricultural multilayer film.
1. An agricultural multilayer film in which an A layer, a B layer and a C layer are laminated in this order,
(1) The A layer contains a polyolefin resin, a triazine ultraviolet absorber and mica, and the content of the mica is 1 to 10 parts by mass relative to 100 parts by mass of the polyolefin resin in the A layer,
(2) The B layer is composed of a single layer or a plurality of layers containing a polyolefin resin, and at least one layer contains a benzotriazole ultraviolet absorber,
(3) the C layer is seen containing a polyolefin resin,
(4) The mica has an average particle size of 5 to 40 μm,
A multi-layer film for agriculture, which is characterized by that.
2 . The agricultural multilayer film according to Item 1, wherein the C layer contains a triazine-based ultraviolet absorber.
3 . 3. The agricultural multilayer film according to item 1 or 2 , wherein the triazine-based UV absorber is a triaryltriazine-based UV absorber.
4 . At least one layer of the A layer, the B layer and the C layer contains a hindered amine light stabilizer in which an organic group or an organic functional group is bonded to a nitrogen atom of a piperidine ring directly or through an oxygen atom, Item 3. The agricultural multilayer film according to any one of Items 1 to 3 .

The agricultural multilayer film of the present invention, in particular,
(1) The A layer contains a polyolefin resin, a triazine ultraviolet absorber and mica, and the content of the mica is 1 to 10 parts by mass relative to 100 parts by mass of the polyolefin resin in the A layer,
(2) The B layer is composed of a single layer or a plurality of layers containing a polyolefin resin, and at least one layer contains a benzotriazole ultraviolet absorber,
(3) The C layer contains a polyolefin resin,
By having a configuration, the effect of suppressing leaf burn of the cultivated product while sufficiently ensuring the total light transmittance, the effect of suppressing ultraviolet rays in a wide range of wavelength region, and excellent long-term sustainability of the ultraviolet suppressing effect, and Excellent in long-term durability of weather resistance.

First, by including a triazine-based UV absorber that is difficult to bleed out in the A layer that is an outer layer when used in a house or the like, the effect of suppressing UV rays and the long-term durability of weather resistance are excellent. Further, by containing 1 to 10 parts by mass of mica with respect to 100 parts by mass of the polyolefin-based resin of the layer A, only the effect of suppressing leaf burn of the cultivated product can be obtained while sufficiently ensuring the total light transmittance. In addition, the bleed-out of the triazine-based UV absorber is suppressed more efficiently. Here, the effect of more effectively suppressing the bleed-out of the triazine-based UV absorber due to the inclusion of mica is that the triazine-based UV absorber contained in the layer A bleeds to the outside because the mica is a layered mineral. It is necessary to move through the gap of the mica which is a layered mineral in order to get out, and it is considered that this is because the time required for bleeding out becomes longer than that in the case where mica is not contained. Further, for the same reason, the benzotriazole-based ultraviolet absorber contained in the layer B described later is also efficiently suppressed from bleeding out through the layer A.

Further, since the B layer, which is the intermediate layer covered with the A layer and the C layer, contains a benzotriazole-based ultraviolet absorber having a wide wavelength range of cuttable ultraviolet rays, it is excellent in the effect of suppressing ultraviolet rays in a wide wavelength range. There is.

Furthermore, since the triazine-based UV absorber and the benzotriazole-based UV absorber are contained in different layers, the extrusion effect due to the high concentration of the UV absorber in the same layer does not occur, so that the UV The bleed-out of the absorbent, especially the bleed-out of the benzotriazole-based ultraviolet absorbent, which is easy to bleed out, is suppressed, and the ultraviolet suppressing effect is excellent in long-term sustainability. Since the benzotriazole-based ultraviolet absorber has a wide wavelength range of ultraviolet light that can be cut, the agricultural film of the present invention can maintain a wide ultraviolet light cut region for a long period of time.

It is sectional drawing which shows an example of the laminated constitution of the agricultural multilayer film of this invention.

Hereinafter, the agricultural multilayer film of the present invention will be described in detail.

The agricultural multilayer film of the present invention is an agricultural multilayer film in which an A layer, a B layer and a C layer are laminated in this order,
(1) The A layer contains a polyolefin resin, a triazine ultraviolet absorber and mica, and the content of the mica is 1 to 10 parts by mass relative to 100 parts by mass of the polyolefin resin in the A layer,
(2) The B layer is composed of a single layer or a plurality of layers containing a polyolefin resin, and at least one layer contains a benzotriazole ultraviolet absorber,
(3) The C layer contains a polyolefin resin,
It is characterized by

First, the agricultural multilayer film contains a triazine-based ultraviolet absorber which is difficult to bleed out in the A layer which is an outer layer when it is used for a house or the like, so that the ultraviolet ray suppressing effect and the long-term durability of weather resistance can be obtained. It has excellent properties. Further, by containing 1 to 10 parts by mass of mica with respect to 100 parts by mass of the polyolefin-based resin of the layer A, only the effect of suppressing leaf burn of the cultivated product can be obtained while sufficiently ensuring the total light transmittance. In addition, the bleed-out of the triazine-based UV absorber is suppressed more efficiently. Here, the effect of more effectively suppressing the bleed-out of the triazine-based UV absorber due to the inclusion of mica is that the triazine-based UV absorber contained in the layer A bleeds to the outside because the mica is a layered mineral. It is necessary to move through the gap of the mica which is a layered mineral in order to get out, and it is considered that this is because the time required for bleeding out becomes longer than that in the case where mica is not contained. Further, for the same reason, the benzotriazole-based ultraviolet absorber contained in the layer B described later is also efficiently suppressed from bleeding out through the layer A.

Further, since the B layer, which is the intermediate layer covered with the A layer and the C layer, contains a benzotriazole-based ultraviolet absorber having a wide wavelength range of cuttable ultraviolet rays, it is excellent in the effect of suppressing ultraviolet rays in a wide wavelength range. There is.

Furthermore, since the triazine-based UV absorber and the benzotriazole-based UV absorber are contained in different layers, the extrusion effect due to the high concentration of the UV absorber in the same layer does not occur, so that the UV The bleed-out of the absorbent, especially the bleed-out of the benzotriazole-based ultraviolet absorbent, which is easy to bleed out, is suppressed, and the ultraviolet suppressing effect is excellent in long-term sustainability. Since the benzotriazole-based ultraviolet absorber has a wide wavelength range of ultraviolet light that can be cut, the agricultural film of the present invention can maintain a wide ultraviolet light cut region for a long period of time.

Hereinafter, each layer of the agricultural multilayer film of the present invention will be described.

(A layer)
The layer A contains a polyolefin resin, a triazine ultraviolet absorber and mica. When the agricultural film of the present invention is used in, for example, a greenhouse for greenhouse cultivation, the A layer is a layer located outside the greenhouse (ie, the outermost layer).

The polyolefin-based resin is not particularly limited, and is a homopolymer of ethylene or α-olefin, a copolymer of ethylene and α-olefin, and a copolymer of ethylene or α-olefin with a different monomer as a main component. , A copolymer of ethylene or α-olefin and a polyunsaturated compound such as a conjugated diene or a non-conjugated diene, acrylic acid, methacrylic acid, vinyl acetate or the like can be used, and for example, high density, low density or direct Chain low density polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-butene copolymer, ethylene-4-methyl-1-pentene copolymer, ethylene-vinyl acetate copolymer (EVA), ethylene-acrylic acid Examples thereof include copolymers. Among these, low-density polyethylene having a density of 0.890 to 0.935 g/cm ³ , an ethylene-α-olefin copolymer, and an ethylene-vinyl acetate copolymer having a vinyl acetate content of 30% by mass or less, It is preferable as an agricultural film in terms of transparency, weather resistance and price.

Further, in the present invention, an ethylene-α-olefin copolymer resin obtained by copolymerizing with a metallocene catalyst can be used as at least one component of the polyolefin resin. This is usually called metallocene polyethylene, and is a copolymer of ethylene and α-olefin such as butene-1, hexene-1, 4-methylpentene-1, octene.

When an ethylene-α-olefin copolymer is used as the polyolefin-based resin, the melt flow rate (MFR) of the ethylene-α-olefin copolymer measured by JIS-K7210 is 0.01 to 10 g/10 min. It is preferably 0.1 to 5 g/10 minutes. By setting the MFR in a preferable range, it is possible to reduce the meandering of the film at the time of molding (during film formation) and the load on the molding machine, so that the moldability can be improved.

Density measured by JIS K7112 of the ethylene -α- olefin copolymer is preferably 0.880 to 0.930 g / cm ^3, more preferably 0.890~0.920g / cm ^3. By setting the density in a preferable range, transparency of the agricultural multi-layer film can be easily ensured, and stickiness of the surface can be reduced to easily prevent blocking.

The molecular weight distribution (weight average molecular weight/number average molecular weight) determined by gel permeation chromatography (GPC) of the ethylene-α-olefin copolymer is preferably 0.5 to 3.5, and 1.0 to 3. 0 is more preferable. By setting the molecular weight distribution in a preferred range, it is possible to reduce the meandering of the film during molding (during film formation) and improve the moldability, and it is easy to ensure the mechanical strength of the agricultural multilayer film.

When an ethylene-vinyl acetate copolymer is used as the polyolefin resin, the vinyl acetate copolymer preferably has a vinyl acetate content of 3 to 25% by mass, more preferably 5 to 20% by mass. By setting the vinyl acetate content within the preferable range, the hardness of the agricultural film can be optimized, and thus wrinkles and slack can be effectively suppressed during the expansion to the house. Further, the slack of the agricultural multi-layer film can be suppressed even at high temperatures in summer, so that flapping due to slack and breakage due to rubbing with the house structure can be easily suppressed.

The layer A contains a triazine-based ultraviolet absorber. The triazine-based UV absorber is not particularly limited, and conventionally known ones can be used. For example, a triaryltriazine-based ultraviolet absorber, bisresorcinyltriazine, bisethylhexyloxyphenol methoxyphenyltriazine (2,4-bis{[4-(2-ethylhexyloxy)-2-hydroxy]phenyl}-6-( 4-methoxyphenyl)1,3,5-triazine), octyltriazone (2,4,6-tris[4-(2-ethylhexyloxycarbonyl)anilino]1,3,5-triazine) and the like. Of these, triaryltriazine-based UV absorbers are preferable.

The content of the triazine-based UV absorber may be 1 to 10 parts by mass, preferably 0.1 to 1 part by mass, and 0.2 to 0, based on 100 parts by mass of the polyolefin-based resin contained in the layer A. 0.7 mass part is more preferable, and 0.3-0.6 mass part is still more preferable. By setting the content within the preferable range, it is possible to sufficiently secure the ultraviolet ray suppressing effect of the agricultural multilayer film and to suppress the bleed-out of the triazine-based ultraviolet absorber.

The triaryltriazine-based ultraviolet absorber preferably has a molecular weight of 600 or more. By using a triaryltriazine-based UV absorber having a molecular weight of 600 or more, the agricultural multilayer film of the present invention exhibits a superior long-term sustainability of the UV-suppressing effect.

The triaryltriazine-based UV absorber is not particularly limited, but for example, a triaryltriazine-based UV absorber represented by the following formula (1) is preferable.

Here, in formula (1), R _{1 to} R ₅ each independently represent a hydrogen atom or an alkyl group having 1 to 10 carbon atoms. Preferably, R ₁ is an alkyl group having 6 to 10 carbon atoms, more preferably an alkyl group having 6 to 8 carbon atoms, and R _{2 to} R ₅ are hydrogen atoms or an alkyl group having 1 to 2 carbon atoms, and more preferably Is a hydrogen atom or a methyl group.

Examples of commercial products of the triaryltriazine-based ultraviolet absorber represented by the above formula (1) include BASF's trade names “TINUVIN 1577F” and “TINUVIN 1600”, and Cytec's trade name “UV1164”. To be

The A layer may include a hindered amine light stabilizer in which an organic group or an organic functional group is bonded to a nitrogen atom of a piperidine ring directly or via an oxygen atom (the hindered amine light stabilizer is the A layer. In addition, it can be contained in at least one of the A layer, the B layer and the C layer, and is particularly preferably contained in all layers of the A layer, the B layer and the C layer). In addition, the organic group means, for example, a methyl group or the like having low reactivity by itself, and the organic functional group means a functional group having reactivity by itself.

Examples of such hindered amine light stabilizers include so-called NR type hindered amine light stabilizers and NOR hindered amine light stabilizers. The NR-type hindered amine-based light stabilizer refers to a hindered amine-based light stabilizer in which a carbon atom is directly bonded to a nitrogen atom of a piperidine ring, and the NOR-type hindered amine-based light stabilizer is a hindered amine-based light stabilizer. Among the light stabilizers, those having a carbon atom bonded to the nitrogen atom of the piperidine ring via an oxygen atom.

The NR-type hindered amine light stabilizer is not particularly limited, and conventionally known ones can be used. For example, an NR-type hindered amine having 1 or 2 or more piperidine ring structures represented by the following formula (2) in the molecule can be mentioned.

Here, in the formula (2), R ₆ is an organic group in which a carbon atom is directly bonded to the nitrogen atom of the piperidine ring, or an organic functional group.

Examples of the organic group or organic functional group in which a carbon atom is directly bonded to the piperidine ring nitrogen atom include, for example, a carbon atom directly bonded to a piperidine ring nitrogen atom, and a carbon number of 1 or more and at least 1 or more. And a functional group or compound containing a methyl group or a methylene group. Examples of the compound having one or more carbon atoms and containing at least one or more methyl group or methylene group include alkyl groups, and also include oligomers and polymers.

Specific examples of the NR-type hindered amine light stabilizers include those represented by the following formulas (3) to (11).

Here, in the formula (11), n is a natural number indicating the degree of polymerization (the number of repeating units).

As the NR type hindered amine light stabilizer, it is preferable to use the one represented by the above formula (11).

Examples of commercial products of the NR type hindered amine light stabilizer represented by the above formula (11) include BASF's trade name “TINUVIN 622”.

The molecular weight of the NR-type hindered amine light stabilizer is preferably 1000 or more, more preferably 2000 or more. By setting the molecular weight in a preferable range, it becomes easy to suppress the bleed-out of the NR type hindered amine light stabilizer. The upper limit of the molecular weight is not particularly limited, but is about 5,000.

The NOR type hindered amine light stabilizer is not particularly limited, and any conventionally known one can be used. For example, NOR-type hindered amines having 1 or 2 or more piperidine ring structures represented by the following formula (12) in the molecule are mentioned.

Here, in the formula (12), R ₇ is an organic group or an organic functional group.

The organic group or organic functional group represents, for example, a functional group or compound having a carbon number of 1 or more and containing at least one methyl group or methylene group. The compound having 1 or more carbon atoms and containing at least one or more methyl group or methylene group also includes oligomers and polymers. Specifically, examples of R ₇ include an alkyl group such as a propyl group.

Specific examples of the NOR type hindered amine light stabilizers include those represented by the following formula (13).

Examples of commercially available NOR hindered amine light stabilizers represented by the above formula (13) include BASF's product name “TINUVIN 123”. Examples of commercially available other NOR-type hindered amine light stabilizers include, for example, BASF's product name “TINUVIN NOR 371”, ADEKA Co., Ltd. product name “LA-81”, and Clariant Japan product name “Hostavin”. "NOW".

The molecular weight of the NOR-type hindered amine light stabilizer is preferably 1000 or more, more preferably 2000 or more. By setting the molecular weight in a preferable range, it becomes easy to suppress the bleed-out of the NOR-type hindered amine light stabilizer. The upper limit of the molecular weight is not particularly limited, but is about 5,000.

The A layer may further contain a hindered amine light stabilizer in which a hydrogen atom is directly bonded to the nitrogen atom of the piperidine ring (so-called NH type hindered amine light stabilizer) (note that the hindered amine light stabilizer is A Not only the layer but also at least one layer of the A layer, the B layer and the C layer can be included, and it is particularly preferable to include it in all the layers of the A layer, the B layer and the C layer). By including the hindered amine light stabilizer, the agricultural multilayer film of the present invention is more excellent in weather resistance.

The NH-type hindered amine light stabilizer is not particularly limited, and conventionally known ones can be used. For example, NH-type hindered amines having 1 or 2 or more piperidine ring structures represented by the following formula (14) in the molecule are mentioned.

Specific examples of the NH-type hindered amine light stabilizers include those represented by the following formulas (15) to (18).

In formula (15), R ₈ is a tert-octyl group, and n is a natural number indicating the degree of polymerization.

As the NH-type hindered amine light stabilizer, it is preferable to use one represented by the above formula (15).

Examples of commercially available NH-type hindered amine light stabilizers represented by the above formula (15) include BASF Corporation's trade name “CHIMASSORB 944”.

The molecular weight of the NH-type hindered amine light stabilizer is preferably 1000 or more, more preferably 2000 or more. By setting the molecular weight in a preferable range, it becomes easy to suppress the bleed-out of the NH-type hindered amine light stabilizer. The upper limit of the molecular weight is not particularly limited, but is about 5,000.

The hindered amine-based light stabilizer preferably contains an NR-type hindered amine-based light stabilizer and an NH-type hindered amine-based light stabilizer. By using such a hindered amine-based light stabilizer, the agricultural multilayer film of the present invention is excellent in the effect of suppressing initial ultraviolet deterioration and is also excellent in long-term sustainability of the effect of suppressing ultraviolet deterioration. Examples of the hindered amine light stabilizer including the NR hindered amine light stabilizer and the NH hindered amine light stabilizer (NR-NH mixed hindered amine light stabilizer) include BASF's trade name “TINUVIN 622” and BASF. The product name "TINUVIN 783" manufactured by BASF, which is a mixture with the product name "CHIMASSORB 944" manufactured by the company, may be mentioned.

When the A layer contains the hindered amine light stabilizer, the content is preferably 0.1 to 3 parts by mass, and 0.2 to 2 parts by mass with respect to 100 parts by mass of the polyolefin resin contained in the A layer. More preferably, 0.3 to 1 part by mass is even more preferable. By setting the content in the preferred range, not only good weather resistance of the agricultural multilayer film can be secured, but also the triazine contained in the layer A when the content of the light stabilizer is in an appropriate range. Bleed-out of the ultraviolet absorbent can be suppressed.

The A layer contains 1 to 10 parts by mass of mica with respect to 100 parts by mass of the polyolefin resin contained in the A layer. When the content of mica is less than 1 part by mass, the scattered light transmittance of the agricultural multi-layer film decreases, and as a result, the leaf burn preventing effect decreases. When the amount of mica is more than 10 parts by mass, the total light transmittance is reduced, which hinders the growth of crops. Therefore, in the present invention, the content of mica is specified to be 1 to 10 parts by mass. Among them, the content of mica is preferably 1.5 to 7 parts by mass, more preferably 2 to 5 parts by mass.

As the mica, naturally produced muscovite, phlogopite, and dry-milled or wet-milled ones thereof can be used. In addition, synthetic mica produced from talc or the like can also be used. In particular, fluoromica, tetrasilicon mica, etc., which can be synthesized by methods such as hydrothermal synthesis, solid-phase reaction synthesis, and melt synthesis, and which have particularly high chemical purity and contain few impurities such as heavy metals that impede transparency. It can be preferably used. Among these, fluorphlogopite represented by the composition formula of K ₂ Mg ₆ Al ₂ Si ₆ O ₂₀ F ₄ and potassium tetrasilicon gold represented by the composition formula of KMg _2.5 Si ₄ O ₁₀ F _2. Mica or the like can be preferably used.

The average particle size of the mica is not limited, but is preferably 5 to 40 μm, more preferably 8 to 30 μm. In addition, the average particle diameter in this specification is a measured value by a laser diffraction method.

The layer A is an inorganic heat retaining agent, an antioxidant, a heat stabilizer, a lubricant, an antistatic agent, a colorant, an antiblocking agent, an antifogging agent, an antifog agent, etc., as long as it does not impair the effects of the present invention. Other additives may also be included.

The inorganic heat retaining agent is not particularly limited, but includes, for example, talc, hydrotalcites, magnesium aluminum complex hydroxide, lithium aluminum complex hydroxide, and other complex hydroxides (alkali metal, alkaline earth metal). , Transition metals, 2B group elements, and hydroxides containing at least two elements selected from 4B group elements of silicon or higher). However, mica is not included in the inorganic heat retaining agent. These may be used alone or in combination of two or more. Above all, it is preferable to use the magnesium aluminum complex hydroxide. By containing the above-mentioned inorganic heat retaining agent, the heat retaining property of the obtained agricultural multilayer film can be improved, and the extrusion fluctuation at the time of film forming can be improved. Here, the extrusion fluctuation means that, for example, when a film in which an antifogging agent (for example, higher fatty acid ester) is kneaded is formed by extrusion, if a large amount of the low melting point antifogging agent is kneaded in the extruder. This is a phenomenon in which the resin composition is difficult to extrude due to slipping.

(B layer)
The layer B is composed of a single layer or a plurality of layers containing a polyolefin resin, and at least one layer contains a benzotriazole ultraviolet absorber.

The polyolefin resin contained in the layer B is not particularly limited, and the same polyolefin resin that can be used in the layer A can be used.

The B layer is composed of a single layer or a plurality of layers containing the above polyolefin resin. The number of layers B is not particularly limited, but is preferably 1 to 3 and more preferably 1 layer.

At least one layer constituting the B layer of the agricultural multilayer film of the present invention contains a benzotriazole-based ultraviolet absorber. The benzotriazole-based ultraviolet absorber is not particularly limited, but for example, 2-(5-chloro(2H)-benzotriazol-2-yl)-4-methyl-6-(tert-butyl)phenol, 2-(2 '-Hydroxy-5'-tert-butylphenyl)benzotriazole, 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2-(2'-hydroxy-3'-tert-butyl-5-methyl Phenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-3',5'-di-tert-butylphenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-3',5'. -Di-tert-amylphenyl)-5-chlorobenzotriazole and the like can be used. These may be used alone or in combination of two or more.

The content of the benzotriazole-based ultraviolet absorber contained in the B layer is preferably 0.1 to 5 parts by mass, and 0.3 to 100 parts by mass with respect to 100 parts by mass of the polyolefin resin contained in the B layer (the entire B layer). 3 parts by mass is more preferable, and 0.5 to 2 parts by mass is further preferable. By setting the content in a preferred range, it is possible to impart a good ultraviolet ray-suppressing effect to the agricultural multilayer film, and at the same time, the content of the benzotriazole-based ultraviolet absorber contained in the layer B Bleed out can be suppressed.

Examples of commercially available benzotriazole-based ultraviolet absorbers include trade names “TINUVIN 326” and “TINUVIN 329” manufactured by BASF.

The B layer may contain a hindered amine light stabilizer in which an organic group or an organic functional group is bonded to the nitrogen atom of the piperidine ring directly or via an oxygen atom. By including the hindered amine light stabilizer, the agricultural multilayer film of the present invention is more excellent in weather resistance.

The hindered amine light stabilizer having an organic group or an organic functional group bonded to the nitrogen atom of the piperidine ring contained in the B layer directly or via an oxygen atom is not particularly limited and may be the same as that used for the A layer. One can be used.

The B layer may further contain a hindered amine light stabilizer in which a hydrogen atom is directly bonded to the nitrogen atom of the piperidine ring. By including the hindered amine light stabilizer, the agricultural multilayer film of the present invention is more excellent in weather resistance.

The hindered amine light stabilizer in which a hydrogen atom is directly bonded to the nitrogen atom of the piperidine ring contained in the B layer is not particularly limited, and the same hindered amine light stabilizers as those usable in the A layer can be used.

When the layer B is composed of a plurality of layers, the hindered amine light stabilizer in which a hydrogen atom is bonded to the nitrogen atom of the piperidine ring has an organic group or an organic functional group directly or via an oxygen atom on the nitrogen atom of the piperidine ring. It may be contained in the same layer as the bound hindered amine light stabilizer, or may be contained in a different layer. A hydrogen atom is present in the nitrogen atom of the piperidine ring from the viewpoint of suppressing the bleed-out of the hindered amine light stabilizer, which occurs due to the extrusion effect resulting from the increase in the concentration of the hindered amine light stabilizer in the same layer. The bound hindered amine light stabilizer is preferably contained in a layer different from the hindered amine light stabilizer in which an organic group or an organic functional group is bonded to the nitrogen atom of the piperidine ring directly or via an oxygen atom.

As described above, the B layer is a hindered amine light stabilizer and/or an organic group or an organic functional group bonded to the nitrogen atom of the piperidine ring directly or via an oxygen atom, as long as the effect of the present invention is not impaired. Alternatively, a hindered amine light stabilizer in which a hydrogen atom is directly bonded to the nitrogen atom of the piperidine ring may be contained. The types and the contents thereof are basically the same as the description in the layer A. Regarding the content of the hindered amine light stabilizer contained in the B layer, it means the parts by mass relative to 100 parts by mass of the polyolefin resin contained in the B layer (the entire B layer) even when the B layer is composed of a plurality of layers. To do.

The layer B is an inorganic heat retaining agent, an antioxidant, a heat stabilizer, a lubricant, an antistatic agent, a colorant, an antiblocking agent, an antifogging agent, an antifog agent, etc., as long as the effects of the present invention are not impaired. Other additives may also be included.

The inorganic heat retaining agent is not particularly limited, but includes, for example, talc, hydrotalcites, magnesium aluminum complex hydroxide, lithium aluminum complex hydroxide, and other complex hydroxides (alkali metal, alkaline earth metal). , Transition metals, 2B group elements, and hydroxides containing at least two elements selected from 4B group elements of silicon or more) and the like. These may be used alone or in combination of two or more. Above all, it is preferable to use the magnesium aluminum complex hydroxide. By containing the above-mentioned inorganic heat retaining agent, the heat retaining property of the obtained agricultural multilayer film can be improved and the fluctuation in extrusion during film molding can be improved.

(C layer)
The layer C is a layer containing a polyolefin resin. The polyolefin resin contained in the C layer is not particularly limited, and the same polyolefin resin that can be used in the A layer can be used.

The C layer preferably contains a triazine-based ultraviolet absorber. Since the C layer contains the triazine-based ultraviolet absorber, the agricultural multilayer film of the present invention is more excellent in the effect of suppressing ultraviolet rays. The triazine-based UV absorber contained in the C layer is not particularly limited, and the same triazine-based UV absorber that can be used in the A layer can be used.

The C layer may contain a hindered amine light stabilizer in which an organic group or an organic functional group is bonded to a nitrogen atom of a piperidine ring directly or via an oxygen atom. By including the hindered amine light stabilizer, the agricultural multilayer film of the present invention is more excellent in weather resistance.

The hindered amine light stabilizer in which an organic group or an organic functional group is bonded to the nitrogen atom of the piperidine ring contained in the C layer directly or through an oxygen atom is not particularly limited, and is the same as that used for the A layer. One can be used.

The C layer may further contain a hindered amine light stabilizer in which a hydrogen atom is directly bonded to the nitrogen atom of the piperidine ring. By including the hindered amine light stabilizer, the agricultural multilayer film of the present invention is more excellent in weather resistance. The hindered amine-based light stabilizer in which a hydrogen atom is directly bonded to the nitrogen atom of the piperidine ring contained in the C layer is not particularly limited, and the same hindered amine light stabilizers as those usable in the A layer can be used.

As described above, the C layer is a hindered amine light stabilizer and/or an organic group or an organic functional group bonded to the nitrogen atom of the piperidine ring directly or via an oxygen atom as long as the effect of the present invention is not impaired. Alternatively, a hindered amine light stabilizer in which a hydrogen atom is directly bonded to the nitrogen atom of the piperidine ring may be contained. The types and the contents thereof are the same as those described in the layer A.

The C layer is an inorganic heat retaining agent, an antioxidant, a heat stabilizer, a lubricant, an antistatic agent, a colorant, an antiblocking agent, an antifogging agent, an antifog agent, etc., as long as it does not impair the effects of the present invention. Other additives may also be included.

The inorganic heat retaining agent is not particularly limited, but includes, for example, talc, hydrotalcites, magnesium aluminum complex hydroxide, lithium aluminum complex hydroxide, and other complex hydroxides (alkali metal, alkaline earth metal). , Transition metals, 2B group elements, and hydroxides containing at least two elements selected from 4B group elements of silicon or higher). These may be used alone or in combination of two or more. Above all, it is preferable to use the magnesium aluminum complex hydroxide. By containing an inorganic heat insulating agent, the heat retention of the resulting agricultural multilayer film can be improved, and the fluctuation in extrusion during film forming can be improved. When the resin composition contains an inorganic heat retaining agent, the effect of suppressing extrusion fluctuation is obtained.

When the agricultural multilayer film of the present invention contains a hindered amine light stabilizer in which a hydrogen atom is directly bonded to the nitrogen atom of the piperidine ring, the content of the hindered amine light stabilizer is 100 parts by mass of the polyolefin resin. The amount is preferably 0.1 to 1.0 part by mass, more preferably 0.3 to 0.6 part by mass. By setting the content in a preferable range, good weather resistance is easily obtained, and a triazine-based ultraviolet absorber in the same layer or an organic group or a nitrogen atom of the piperidine ring directly or via an oxygen atom. When a hindered amine-based light stabilizer to which an organic functional group is bound is contained, it is easy to suppress the bleed-out of these ultraviolet absorbers and light stabilizers.

When the agricultural multilayer film of the present invention contains an inorganic heat retaining agent, the content of the inorganic heat retaining agent is preferably 1 to 10 parts by mass, and 3 to 8 parts by mass with respect to 100 parts by mass of the polyolefin resin. Is more preferable. By setting the content within the preferable range, it is possible to easily impart good heat-retaining property to the agricultural multilayer film, and it is easy to sufficiently obtain the effect of improving extrusion fluctuation during film formation by extrusion molding.

When the agricultural multilayer film of the present invention contains the hindered amine light stabilizer, the content of the hindered amine light stabilizer is 0.1 to 3 parts by mass based on 100 parts by mass of the polyolefin resin. The content is preferably 0.2 to 2 parts by mass, more preferably 0.3 to 1 part by mass. By setting the content in the preferred range, in addition to ensuring good weather resistance of the agricultural multilayer film, the ultraviolet light contained in the agricultural multilayer film by containing the light stabilizer in an appropriate range. Bleed out of the absorbent can be suppressed.

As shown in FIG. 1, the agricultural multilayer film of the present invention has the above-mentioned A layer, B layer, and C layer laminated in this order. FIG. 1 is a sectional view showing an example of the layer structure of the agricultural multilayer film of the present invention. When using the agricultural multilayer film of the present invention for greenhouse cultivation or tunnel cultivation, by using the layer A so as to be on the outside of the house or the like, the effect of suppressing ultraviolet rays in a wide wavelength range, and the effect of suppressing ultraviolet rays. It is possible to efficiently exhibit the effect of the present invention that is excellent in long-term sustainability and excellent in long-term sustainability of weather resistance.

The thickness of the agricultural multilayer film of the present invention is not particularly limited, but is preferably 30 to 300 μm, more preferably 50 to 200 μm, and further preferably 75 to 150 μm. By setting the thickness in a preferable range, the agricultural multilayer film has appropriate elasticity, and good handleability and workability are easily obtained.

The thickness ratio of each layer constituting the agricultural multilayer film of the present invention is preferably A layer:B layer:C layer=1:1:1 to 1:6:1, and 1:2:1 to 1:1. 4:1 is more preferred. By setting the thickness ratio of each layer to a preferable range, not only the benzotriazole-based UV absorber contained in the B layer can be easily prevented from bleeding out into the agricultural multilayer film, but also the weather resistance of the benzotriazole-based UV absorber can be improved. The effect of improving the property is easily obtained.

Examples of the present invention will be described below. The present invention is not limited to the examples below.

Examples 1-10, Comparative Examples 1-4
Polyolefin resin, mica, ultraviolet absorber, light stabilizer, and magnesium aluminum so that each layer of layer A, layer B, and layer C has the composition shown in Table 1 in each extruder of the three-layer extruder. The system composite hydroxide was added and melt-kneaded.

The three layers were co-extruded by the inflation method so that the thickness of each of the A layer, the B layer, and the C layer was A layer:B layer:C layer=1:3:1 (thickness ratio 20:60:20). An agricultural multilayer film having a thickness of 150 μm was obtained.

The polyolefin-based resin, mica, triazine-based UV absorber, benzotriazole-based UV absorber, NR-NH mixed hindered amine-based light stabilizer, and magnesium-aluminum-based composite hydroxide forming each layer are shown in Table 2. Using.

The following evaluation was performed about the obtained agricultural multilayer films of Examples 1-10 and Comparative Examples 1-4.

<Total light transmittance measurement test>
According to JIS K7105, the total light transmittance was measured using a haze meter immediately after producing the agricultural multilayer film.

<Diffused light transmittance measurement test>
According to JIS K7105, the diffused light transmittance was measured using a haze meter immediately after producing the agricultural multilayer film.

<Weather resistance test>
After irradiating for 4000 hours by a xenon weather test by the measuring method according to JIS K7350-2 (ISO4892-2), the residual elongation was measured by the tensile breaking elongation measuring method according to JIS K7128 and evaluated according to the following criteria.
⊚: Residual elongation is 80% or more of the initial value ◯: Residual elongation is 60% or more and less than 80% of the initial value Δ: Residual elongation is 40% or more and less than 60% of the initial value ×: The residual elongation is less than 40% of the initial value

<UV suppression test> (Initial UV suppression test)
With respect to the agricultural multilayer film immediately after production, the visible ultraviolet spectrum was measured using a spectrophotometer by the measuring method according to JIS K0115, and the cut range in the ultraviolet region and the cut rate were evaluated according to the following criteria.
⊚: Total light transmittance at 300 to 380 nm is less than 2% ◯: Total light transmittance at 300 to 380 nm is 2% or more and less than 5% Δ: Total light transmittance at 300 to 380 nm is 5% or more 10 %: less than %: total light transmittance at 300 to 380 nm is 10% or more

<Persistence test of UV suppression effect>
About the agricultural multilayer film after being exposed outdoors for 3 years, the visible ultraviolet spectrum was measured using a spectrophotometer by the measuring method according to JIS K0115, and the cut range and cut rate in the ultraviolet region were evaluated according to the following criteria. did.
⊚: Total light transmittance at 340 nm is less than 2% ◯: Total light transmittance at 340 nm is 2% or more and less than 5% Δ: Total light transmittance at 340 nm is 5% or more and less than 10% x: Total light transmittance at 340 nm is 10% or more

The results are shown in Table 1.

In addition, in Table 2, MFR is a value measured under the conditions of a temperature of 190° C. and a load of 21.18 N in accordance with JIS K-7210.

1... Multilayer film for agriculture 2... A layer 3... B layer 4... C layer

Claims (4)

An agricultural multilayer film in which an A layer, a B layer and a C layer are laminated in this order,
(1) The A layer contains a polyolefin resin, a triazine ultraviolet absorber and mica, and the content of the mica is 1 to 10 parts by mass relative to 100 parts by mass of the polyolefin resin in the A layer,
(2) The B layer is composed of a single layer or a plurality of layers containing a polyolefin resin, and at least one layer contains a benzotriazole ultraviolet absorber,
(3) the C layer is seen containing a polyolefin resin,
(4) The mica has an average particle size of 5 to 40 μm,
A multi-layer film for agriculture, which is characterized by that. The agricultural multilayer film according to claim 1, wherein the C layer contains a triazine-based ultraviolet absorber. The agricultural multilayer film according to claim 1 or 2 , wherein the triazine-based UV absorber is a triaryltriazine-based UV absorber. At least one of the A layer, the B layer, and the C layer contains a hindered amine light stabilizer in which an organic group or an organic functional group is bonded to a nitrogen atom of a piperidine ring directly or through an oxygen atom. Item 3. The agricultural multilayer film according to any one of Items 1 to 3 .