JP2006159784A - Polyolefin-based agricultural film resistant to agricultural chemicals - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an agricultural film transparent, having resistance to degradation factors, having good resistance to chemicals such as fertilizers and agricultural chemicals, having high heat retaining property, excellent in mechanical properties, and maintaining good anti-clouding/dew-running-off property over a long period of time. <P>SOLUTION: The polyolefin-based agricultural film resistant to agricultural chemicals is formed by laminating layer (A)/layer (B)/layer (C) (mentioned below) in this order and incorporates a hindered amine type light stabilizer. The layer (A) is mainly composed of a polyethylene resin. The layer (B) is mainly composed of an ethylene-vinyl acetate copolymer having a vinyl acetate content of 5-20 wt% and a melt mass flow rate of 0.5-4.0 g/10 min (190°C) and contains a polyvinyl alcohol resin and an inorganic heat retaining agent. The layer (C) is mainly composed of an ethylene-vinyl acetate copolymer having a vinyl acetate content of 3-15 wt% and a melt mass flow rate of 0.5-4.0 g/10 min (190°C). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a polyolefin-based agricultural film. More specifically, the present invention relates to a pesticide-resistant polyolefin agricultural film excellent in transparency, pesticide resistance, heat retention, anti-fogging and drip resistance, and mechanical strength. More specifically, the present invention relates to a polyolefin-based agricultural film having excellent pesticide resistance and used as a coating film for a cultivation method in which sulfur fumigation is performed for a long period of time in an agricultural house.

Generally, as a covering film spread in an agricultural house, an agricultural polyvinyl chloride film (hereinafter abbreviated as “agricultural PVC film”), an agricultural polyolefin film (hereinafter referred to as “agricultural PO film”) (Abbreviated) is used.
Conventionally, widely used PVC films for agriculture have excellent heat retention, weather resistance, transparency, and workability, but toxic gas is generated at the time of incineration after use. is doing.

Thus, recently, the use of agricultural PO-based films has rapidly increased as a substitute for agricultural PVC-based films. Agricultural PO films have many advantages over agricultural PVC films in terms of price, processability, mechanical strength, and ease of disposal.
However, agricultural PO-based films have a weaker aspect against deterioration factors such as ultraviolet rays and heat when used outdoors than agricultural PVC-based films. That is, since weather resistance is inferior, various studies have been made to enable outdoor use over a long period of time and outdoor use in areas where use conditions are severe.

As a method for improving the resistance of the agricultural PO film to the deterioration factor, for example, an agricultural film containing a hindered amine light stabilizer as a stabilizer is disclosed. (Refer to Patent Documents 1 and 2) This can improve resistance to deterioration factors such as ultraviolet rays and improve weather resistance, but in an environment where chemicals such as fertilizers and agricultural chemicals are used in the cultivation facility However, the above method cannot improve the deterioration of the film and cannot be used for a long period of time. Furthermore, when using a film for a long period of time, the heat retention in a cultivation facility is needed. However, when only an inorganic heat insulating agent such as lithium-aluminum composite hydroxide salt (Patent Document 2) or hydrotalcite (see Patent Document 3) is used as a heat insulating agent, the transparency is good. In particular, since the above-mentioned heat retaining agent adsorbs components generated from acidic substances such as sulfur and chlorine, there has been a problem of further promoting the deterioration of the film.
In general, heat retention means that the coating film absorbs and reflects the night radiant heat from the ground where the temperature increased due to the absorption of solar heat during the day, and the temperature inside the house (air temperature and ground temperature). ).

JP 59-86645 A JP 7-312996 A JP 2000-109623 A

  In the agricultural PO-based film, the present invention has good transparency, resistance to deterioration factors such as ultraviolet rays and heat, as well as resistance to chemicals such as fertilizers and agricultural chemicals, and An object of the present invention is to provide an agricultural film that retains high heat retaining properties, has excellent mechanical properties, and maintains good anti-fogging droplet performance for a long period of time.

The invention according to claim 1 is composed mainly of a polyethylene resin having a density of 0.90 to 0.93 g / cm ³ and a melt mass flow rate of 0.5 to 7.0 g / 10 min (190 ° C.). Layer (A) comprising a resin component, an ethylene-vinyl acetate copolymer having a vinyl acetate content of 5 to 20% by weight and a melt mass flow rate of 0.5 to 4.0 g / 10 min (190 ° C.) A layer (B) comprising a polyvinyl alcohol resin having a thermoplastic as a main component and an inorganic heat retention agent, a vinyl acetate content of 1 to 15% by weight, and a melt mass flow rate of 0.5 to 4. A layer (C) composed of a resin component mainly composed of an ethylene-vinyl acetate copolymer at 0 g / 10 minutes (190 ° C.) is laminated in the order of layer (A) / layer (B) / layer (C). Polyolefin agricultural fill The hindered amine light stabilizer is 0.02 to 5 parts by weight based on 100 parts by weight of the resin component constituting the film in at least one of the layers (A), (B) and (C). Further, the total of the polyvinyl alcohol resin and the inorganic heat insulating agent is 3 to 15 parts by weight with respect to 100 parts by weight of the resin component constituting the film, and the polyvinyl alcohol resin and the inorganic heat insulating agent. A chemical-resistant polyolefin agricultural film characterized in that the ratio is 1/9 to 9/1.

  In the invention according to claim 2, the content of the α-olefin having 3 to 30 carbon atoms in the polyvinyl alcohol-based resin is 0.5 to 20 mol%, and the saponification degree of the vinyl acetate component is 60 to 99.9 mol%. 2. The chemically resistant polyolefin agricultural film according to claim 1, wherein the film is a saponified α-olefin-vinyl acetate copolymer having a polymerization degree of 50 to 50,000.

The invention according to claim 3 is characterized in that the hindered amine light stabilizer has at least two piperidine ring structures represented by the following formula (1) and has an average molecular weight of 1000 or more. 1. A chemical-resistant polyolefin agricultural film according to 1 and 2.

（１）
（Ｒは炭素数１以上で、少なくとも１以上のメチレン基を含む、官能基もしくは化合物（オリゴマー、ポリマー含む）を表す）

(1)
(R represents a functional group or compound (including oligomer and polymer) having 1 or more carbon atoms and containing at least one methylene group)

  Invention of Claim 4 contains the at least 1 chosen from the group which an inorganic type heat insulating agent becomes from hydrotalcite and lithium aluminum complex hydroxide, The Claims 1-3 characterized by the above-mentioned. This is a chemical-resistant polyolefin agricultural film.

  As the polyolefin resin used for the layer (A) constituting the chemical resistant polyolefin agricultural film of the present invention, those conventionally used for agricultural films are used. Specific examples include polyethylene resins, ethylene-α-olefin copolymers, ethylene-vinyl acetate copolymers, polypropylene resins, propylene-α-olefin copolymers, propylene-vinyl acetate copolymers, and the like. . These may be used alone or in combination of two or more.

  Among the polyolefin resins, polyethylene resin (low density polyethylene, medium density polyethylene, high density polyethylene), ethylene-α-olefin copolymer (as α-olefin, for example, propylene, 1-butene, 4-methyl- 1-pentene, 1-hexene, 1-octene and the like are preferable, and an ethylene-α-olefin copolymer is more preferable.

The density of the polyethylene resin used for the layer (A) is 0.90 to 0.93 g / cm ³ , and the melt mass flow rate is 0.5 to 7.0 g / 10 minutes (190 ° C.). In addition, the density as used in the field of this invention means the density measured based on JIS K-7112 "The measurement method of the density of plastic-non-foamed plastic and specific gravity", and the melt mass flow rate as used in the present invention and Means a melt mass flow rate measured according to JIS K-7210 “Plastics—Test methods for melt mass flow rate and melt volume flow rate of thermoplastics”.

When the density of the polyethylene resin is less than 0.90 g / cm ³ , the mechanical strength of the chemical-resistant polyolefin agricultural film obtained is insufficient. Further, the films cause blocking, and it becomes difficult to feed the film from the original roll. On the contrary, if the density exceeds 0.93 g / cm ³ , the transparency of the resulting chemical-resistant polyolefin agricultural film is lowered.

  When the melt mass flow rate of the polyethylene resin is less than 0.5 g / 10 min (190 ° C.), the productivity (film formation stability) of the chemical-resistant polyolefin agricultural film is hindered. If it exceeds 7.0 g / 10 minutes (190 ° C.), the mechanical strength of the resulting chemically resistant polyolefin agricultural film becomes insufficient.

  The vinyl acetate content in the ethylene-vinyl acetate copolymer used for the layer (B) is 5 to 20% by weight, and the preferred vinyl acetate content is 10 to 15% by weight. When the vinyl acetate content in the ethylene-vinyl acetate copolymer is less than 5% by weight, the resulting chemically resistant polyolefin agricultural film has insufficient flexibility, and conversely, the vinyl acetate content is 20% by weight. If it exceeds 1, the mechanical strength of the resulting chemical-resistant polyolefin agricultural film is lowered.

  The melt mass flow rate of the ethylene-vinyl acetate copolymer used for the layer (B) is 0.5 to 4.0 g / 10 min (190 ° C.). In addition, the density as used in the field of this invention means the density measured based on JIS K-7112 "The measurement method of the density of plastic-non-foamed plastic and specific gravity", and the melt mass flow rate as used in the present invention and Means a melt mass flow rate measured according to JIS K-7210 “Plastics—Test methods for melt mass flow rate and melt volume flow rate of thermoplastics”. When the melt mass flow rate of the ethylene-vinyl acetate copolymer is less than 0.5 g / 10 min (190 ° C.), the productivity (film formation stability) of the chemically resistant polyolefin agricultural film is hindered. When the melt mass flow rate exceeds 4.0 g / 10 min (190 ° C.), the mechanical strength of the resulting chemically resistant polyolefin agricultural film becomes insufficient.

  The polyvinyl alcohol resin contained in the layer (B) is a saponified product of a copolymer comprising an α-olefin and vinyl acetate. The α-olefin has 3 to 30 carbon atoms, preferably 4 to 15 carbon atoms. The α-olefin content is 0.5 to 20 mol%, preferably 5 to 15 mol%, more preferably 7 to 10 mol%. If the α-olefin content is less than 0.5 mol%, the molding stability of the film is lowered. Conversely, if the α-olefin content is more than 20 mol%, the pesticide resistance is lowered and sufficient. Neither heat retention is expressed. The saponification degree of vinyl acetate of the polyvinyl resin is 60 to 99.9 mol%, preferably 70 to 95 mol%, more preferably 80 to 90 mol%. When the saponification degree of vinyl acetate is less than 60 mol%, the pesticide resistance is lowered and sufficient heat retention is not exhibited. The degree of polymerization of the polyvinyl resin is 50 to 50,000, preferably 200 to 10,000. If the degree of polymerization is less than 50, the film formation stability of the film is insufficient, and conversely, even if the degree of polymerization is greater than 50000, the moldability of the film decreases.

  Examples of the inorganic heat insulating agent used in the present invention include magnesium oxide, calcium oxide, aluminum oxide, magnesium carbonate, calcium carbonate, magnesium sulfate, calcium sulfate, aluminum sulfate, lithium phosphate, calcium phosphate, magnesium silicate, calcium silicate, Aluminum silicate, kaolin, clay, talc, hydrotalcite, lithium aluminum composite hydroxide, other composite hydroxides (selected from alkali metals, alkaline earth metals, transition metals, Group 2B elements, Group 4B elements over silicon) And hydroxides having at least two or more elements). These may be used alone or in combination of two or more. Among these, those selected from the group consisting of hydrotalcites and lithium aluminum composite hydroxides are preferably used. Examples of hydrotalcites include DHT-4A (manufactured by Kyowa Chemical Industry), and examples of lithium aluminum composite hydroxides include Mizukarak (manufactured by Mizusawa Chemical Industry) and Fujirain LS (manufactured by Fuji Chemical).

  The total amount of the polyvinyl alcohol-based resin and the inorganic heat-retaining agent contained in the layer (B) is 1 to 15 parts by weight with respect to 100 parts by weight of the resin component of the entire chemical-resistant polyolefin agricultural film of the present invention. The amount is preferably 3 to 13 parts by weight, more preferably 6 to 10 parts by weight. When the total content of the polyvinyl alcohol resin and the inorganic heat retention agent is less than 1 part by weight, sufficient heat retention is not expressed, and conversely, the total content of the polyvinyl alcohol resin and the inorganic heat retention agent is When it exceeds 15 parts by weight, the transparency of the chemical-resistant polyolefin agricultural film is extremely deteriorated, the mechanical strength is lowered, and the film formation stability of the film is lowered.

  The weight ratio of the polyvinyl alcohol resin and the inorganic heat insulating agent in the layer (B) is 1/9 to 9/1, preferably 2/8 to 8/2, more preferably 3/7 to 7 /. 3. When the polyvinyl alcohol resin is more than 9/1 relative to the inorganic heat insulating agent, the transparency of the chemically resistant polyolefin agricultural film is extremely deteriorated and the strength at break is lowered. Moreover, when polyvinyl alcohol-type resin is less than 1/9 with respect to an inorganic type heat retention agent, tear strength falls and pesticide resistance becomes bad.

  The vinyl acetate content in the ethylene-vinyl acetate copolymer used for the layer (C) is 3 to 15% by weight, and preferably the vinyl acetate content is 5 to 10% by weight. When the vinyl acetate content in the ethylene-vinyl acetate copolymer is less than 3% by weight, the resulting chemical-resistant polyolefin agricultural film has insufficient flexibility and is provided with anti-fogging as required. The adhesion of the coating film (D) decreases. Conversely, if the vinyl acetate content exceeds 15% by weight, the mechanical strength of the resulting chemically resistant polyolefin agricultural film will decrease, and the films will block each other, making it difficult to unwind the film from the raw roll. It becomes.

  The melt mass flow rate of the ethylene-vinyl acetate copolymer used for the layer (C) is 0.5 to 4.0 g / 10 min (190 ° C.). When the melt mass flow rate of the ethylene-vinyl acetate copolymer is less than 0.5 g / 10 minutes (190 ° C.), the productivity (film formation stability) of the chemical-resistant polyolefin-based agricultural film is hindered. When the melt mass flow rate exceeds 4.0 g / 10 min (190 ° C.), the mechanical strength of the resulting chemically resistant polyolefin agricultural film becomes insufficient.

  In the present invention, at least one layer in the layer (A), layer (B), and layer (C) is a hindered amine light stabilizer with respect to 100 parts by weight of the resin component of the entire chemically resistant polyolefin agricultural film. Is added by 0.02 to 5 parts by weight.

  As the hindered amine light stabilizer, any conventionally known hindered amine stabilizer may be used. Specifically, for example, dimethyl-1- (2-hydroxyethyl) -4-hydroxy-2,2,6,6 succinate -Tetramethylpiperidine polycondensate, tetrakis (2,2,6,6-tetramethyl-4-piperidyl) -1,2,3,4-butanetetracarboxylate, poly {[6-[(1,1, 3,3-tetramethylbutyl) amino] -1,3,5-triazine-2,4-diyl] [(2,2,6,6-tetramethyl-4-piperidyl) imino] hexamethylene [(2, 2,6,6-tetramethyl-4-piperidyl) imino]}, hindered amine compounds having a piperidine ring structure represented by the following formula (1), and the like. Among these, a hindered amine compound having a piperidine ring structure represented by the following formula (1) is preferably used, and examples thereof include a compound represented by the following formula (2).

（１）
（Ｒは炭素数１以上で、少なくとも１以上のメチレン基を含む、官能基もしくは化合物（オリゴマー、ポリマー含む）を表す。）

(1)
(R represents a functional group or compound (including oligomer and polymer) having 1 or more carbon atoms and containing at least one methylene group.)

（２）
（式中、ｎは１〜２０の整数を表し、Ｒ１は互いに独立しているが、少なくとも一つは、ＯＲ基であり、それ以外は、水素原子、炭素数１〜８のアルキル基、ＯＨ基、ＣＨ２ＣＮ基、炭素数１〜１８のアルコキシ基、炭素数５〜１２のシクロアルコキシ基、炭素数３〜６のアルケニル基、非置換または１，２もしくは３個の炭素原子数１〜４のアルキル基によりフェニル環が置換された炭素数７〜９のフェニルアルキル基、あるいは、炭素数１〜８のアシル基を表し、Ｒ２は、Ｒ１に対して定義された意味の内の一つを表し、Ｘは炭素数２〜１０のアルキレン基を表し、そしてＹは−Ｏ−、または−ＮＨ−を表す。）

(2)
(In the formula, n represents an integer of 1 to 20, and R1 are independent of each other, but at least one is an OR group, and other than that, a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, OH Group, CH2CN group, alkoxy group having 1 to 18 carbon atoms, cycloalkoxy group having 5 to 12 carbon atoms, alkenyl group having 3 to 6 carbon atoms, unsubstituted or 1, 2 or 3 carbon atoms having 1 to 4 carbon atoms Represents a phenylalkyl group having 7 to 9 carbon atoms in which the phenyl ring is substituted by an alkyl group, or an acyl group having 1 to 8 carbon atoms, and R2 represents one of the meanings defined for R1. X represents an alkylene group having 2 to 10 carbon atoms, and Y represents —O— or —NH—.)

  Commercially available hindered amine compounds having two or more piperidine ring structures and a molecular weight of 1000 or more include TINUVIN NOR 371 (Ciba Specialty Chemicals), Adekastab LA-900 (Asahi Denka), and the like. And preferably used.

  The amount of the hindered amine light stabilizer added is 0.02 to 5 parts by weight with respect to 100 parts by weight of the resin component of the entire chemical-resistant polyolefin agricultural film. When the content of the hindered amine light stabilizer is less than 0.02 parts by weight, the resistance (weather resistance) due to deterioration factors such as ultraviolet rays and heat decreases, and conversely, the content of the hindered amine light stabilizer is 5 If the amount is more than parts by weight, the chemical-resistant polyolefin agricultural film is colored, and the effect of addition is not recognized for the amount, which is economically disadvantageous.

The chemical-resistant polyolefin agricultural film of the present invention is formed by laminating the layer (A), the layer (B), and the layer (C) in this order, and the layer (A) is on the outside.

  The chemical-resistant polyolefin agricultural film of the present invention may contain a heat stabilizer, an antioxidant, an ultraviolet absorber, an antifoggant, a lubricant, a pigment, etc., as long as the physical properties are not impaired as necessary. good. Examples of the heat stabilizer include any conventionally known ones, and specific examples include carboxylic acid metal salts, phenolic antioxidants, and chelators such as organic phosphites.

  Examples of the antioxidant include any conventionally known ones. Usually, many of them also have an effect as the heat stabilizer, such as metal salts of carboxylic acids, phenolic antioxidants, organic phosphites. And other chelators.

  Examples of the ultraviolet absorber include conventionally known arbitrary ones. For example, benzophenone series, benzotriazole series, salicylic acid ester series, cyanoacrylate series and the like can be used alone or in admixture of two or more. Specifically, as a benzophenone ultraviolet absorber, 2,4-dihydroxybenzophenone, 2-hydroxy-4-octoxybenzophenone, 2-hydroxy-4-dodecyloxybenzophenone, 2,2′-dihydroxy-4-methoxybenzophenone, As a benzotriazole ultraviolet absorber, such as 2,2'-hydroxy-4,4'-dimethoxybenzophenone, 2-hydroxy-4-methoxy-5-sulfobenzophenone, 2- (2'-hydroxy-5'-tert- Butylphenyl) benzotriazole, 2- (2′-hydroxy-5′-methylphenyl) benzotriazole, 2- (2′-hydroxy-3′-tert-butyl-5-methylphenyl) -5-chlorobenzotriazole, 2- (2'-hydroxy-3 ', 5'-di tert- butylphenyl) -5-chloro-benzotriazole, 2- (2'-hydroxy-3 ', 5'-di -tert- amylphenyl) -5-chloro-benzotriazole, and the like.

  As said anti-fogging agent, conventionally well-known arbitrary things are mentioned, For example, surfactants, such as silicone type and a fluorine type, are mentioned.

  Examples of the lubricant include conventionally known arbitrary ones, saturated fatty acid amides such as stearic acid amide, unsaturated fatty acid amides such as erucic acid amide and oleic acid amide, bisamides such as ethylene bis stearic acid amide and the like. .

  The chemical-resistant polyolefin-based agricultural film of the present invention has the above-mentioned layer (A), layer (B), layer (C) laminated in this order, and an agricultural house or the like such that the layer (A) is on the outside. It is extended. At this time, an antifogging agent is kneaded into the inner surface (layer (C) side), if necessary, in order to make water droplets condensed on the inner surface (layer (C) side) flow. It is preferable to do so.

  Examples of the antifogging agent kneaded into the chemical-resistant polyolefin agricultural film of the present invention include any conventionally known antifogging agent, and polyhydric alcohol fatty acid esters are preferably used. Specifically, polyvalent alcohol saturated fatty acid esters such as glycerin stearic acid ester, diglycerin stearic acid ester, polyglycerin stearic acid ester, sorbitol stearic acid ester, or polyvalent alcohols such as glycerin oleic acid ester and diglycerin oleic acid ester. Examples thereof include alcohol unsaturated fatty acid esters.

  Examples of the antifogging film formed on the layer (C) side of the chemical-resistant polyolefin agricultural film of the present invention include, for example, a coating film of inorganic oxide sol represented by colloidal silica and colloidal alumina, and inorganic oxide sol. And organic compound (surfactant, resin, etc.) coating film, surfactant-based liquid coating film, hydrophilic resin-based film (eg, polyvinyl alcohol, polyethylene oxide, polysaccharides, And polyacrylic acid). Examples of methods for forming these films include a roll coating method using a gravure coater, a bar code method, a dip coating method, a spray method, a brush coating method, and the like.

  The method for producing the chemical-resistant polyolefin agricultural film of the present invention is not particularly limited, and any conventionally known method may be employed, for example, a multilayer inflation method, a multilayer T-die method, a multilayer laminate method, a calendar. Law.

  As the thickness of the chemical-resistant polyolefin-based agricultural film decreases, the mechanical strength decreases. On the other hand, when the thickness increases, cutting, joining, stretching work and the like become difficult, and the handleability decreases. Preferably, it is 50-200 micrometers.

  The chemical-resistant polyolefin-based agricultural film of the present invention has the above-described configuration, so it has excellent mechanical strength, resistance to deterioration factors such as ultraviolet rays and heat, as well as chemicals such as fertilizers and agricultural chemicals. It is an agricultural film that has good resistance and can maintain high heat retention, and can be suitably used for a long period of time. Furthermore, the heat retention effect can be further improved by specifying the polyvinyl alcohol resin. Moreover, weather resistance can be further improved by using a specific hindered amine light stabilizer.

Hereinafter, embodiments of the present invention will be described in more detail with reference to examples. However, the present invention is not limited to these examples.
Example 1
(Manufacture of chemical-resistant polyolefin-based agricultural films)
Three types of resin compositions for forming the layer (A), the layer (B) and the layer (C) with the formulation shown in Example 1 of Table 1 were put into separate extruders and kneaded. A chemically resistant polyolefin-based agricultural film comprising a three-layer laminate having a total thickness of 150 μm laminated in the order of layer (A), layer (B) and layer (C) was obtained. The thickness ratio of layer (A) / layer (B) / layer (C) is 15/70/15.

(Examples 2 to 10)
Three types of resin compositions for forming the layer (A), the layer (B) and the layer (C) of Examples 2 to 10 in Table 1 were respectively put into separate extruders and kneaded, and then the layers A polyolefin-based agricultural film comprising a three-layer laminate having a total thickness of 150 μm laminated in the order of (A), layer (B) and layer (C) was obtained. The thickness ratio of layer (A) / layer (B) / layer (C) is 15/70/15.

(Comparative Examples 1-6)
Three types of resin compositions for forming the layer (A), the layer (B) and the layer (C) shown in Comparative Examples 1 to 6 in Table 2 were respectively put into separate extruders and kneaded, A polyolefin-based agricultural film comprising a three-layer laminate having a total thickness of 150 μm laminated in the order of layer (A), layer (B) and layer (C) was obtained. The thickness ratio of layer (A) / layer (B) / layer (C) is 15/70/15.

(Evaluation)
About the agricultural film obtained above, the breaking strength, tear strength, accelerated weather resistance, agricultural chemical resistance, heat retention, and haze value were evaluated by the following methods, and the results are shown in Tables 1 and 2.

(Strength at break)
Using a strograph (manufactured by Toyo Seiki Seisakusho), the breaking strength of the agricultural film was measured according to JIS K 6781, and the breaking strength was evaluated according to the following criteria.
A: The strength at break was 25.0 N or more.
○ The strength at break was 22.5 N or more and less than 25.0 N.
Δ: The strength at break was 20.0 N or more and less than 22.5 N.
X: The strength at break was less than 20.0 N.

(Tear strength)
The tear strength of the agricultural film was measured according to JIS K 7128 using an Elmendorf tear strength measuring machine (manufactured by Toyo Seiki Seisakusho), and the tear strength was evaluated according to the following criteria.
A: The tear strength was 25.0 N or more.
B: The tear strength was 22.5N or more and less than 25.0N.
Δ: Tear strength was 20.0 N or more and less than 22.5 N.
X: The tear strength was less than 20.0N.

(Accelerated weather resistance)
Using a Sunshine Super Long Life Weather Meter (manufactured by Suga Test Co., Ltd.), irradiation was performed for 800 hours under the conditions of a black panel temperature of 63 ° C. and a water spraying time of 12 minutes / 1 hour, in accordance with JIS K 6781. The elongation at break of the agricultural film was measured, and the accelerated weather resistance was evaluated according to the following criteria.
A: The elongation at break was 600% or more.
B: The elongation at break was 400% or more and less than 600%.
Δ: The elongation at break was 200% or more and less than 400%.
X: The elongation at break was less than 200%.

(Pesticide resistance)
The agricultural film cut to 15 cm long × 15 cm wide was immersed in a 5 wt% aqueous sulfurous acid solution for 1 day, then taken out, and irradiated with 50 W / m 2 of ultraviolet rays for 24 hours with an ultraviolet lamp. After this immersion and UV irradiation cycle was repeated three times, the elongation at break of the agricultural film after repetition was measured according to JIS K 6781 “Agricultural polyethylene film”, and the chemical resistance was measured according to the following criteria: Evaluated.
A ... The residual elongation at break was 500% or more.
B: The residual elongation at break was 350% or more and less than 500%.
Δ: The residual elongation at break was 200% or more and less than 350%.
X: The residual elongation at break was less than 200%.

(Heat retention)
The absorption spectrum of the film is measured using an infrared spectrophotometer (FT / IR-410, manufactured by JASCO Corporation), and the spectral radiant divergence (1) radiated from the ground is weighted by the absorption rate of each wavelength. Calculate the corrected spectral radiant divergence (2), and use the ratio of the spectral radiant divergence (1) and the corrected spectral radiant divergence (2) as an index of heat retention. went.
○: The heat retention was 80% or more.
Δ: The heat retention was 70% or more and less than 80%.
X: The heat retention was less than 70%.

(transparency)
The haze value of the film immediately after production was measured with a haze meter (NDH2000, manufactured by Nippon Denshoku Industries Co., Ltd.), and the transparency was evaluated according to the following criteria.
○: The haze value was less than 20%.
Δ: Haze value was 20% or more and less than 25%.
X: The haze value was 25% or more.

Claims (4)

A layer (A) mainly composed of a polyolefin resin having a density of 0.90 to 0.93 g / cm ³ and a melt mass flow rate of 0.5 to 7.0 g / 10 min (190 ° C.), vinyl acetate The main component is an ethylene-vinyl acetate copolymer having a content of 5 to 20% by weight and a melt mass flow rate of 0.5 to 4.0 g / 10 min (190 ° C.). A layer (B) comprising a heat-retaining agent, an ethylene-vinyl acetate copolymer having a vinyl acetate content of 3 to 15% by weight and a melt mass flow rate of 0.5 to 4.0 g / 10 min (190 ° C.). In the polyolefin agricultural film in which the layer (C) mainly composed of a polymer is laminated in the order of layer (A) / layer (B) / layer (C), the layer (A), the layer (B), In at least one layer of the layer (C), A hindered amine light stabilizer is blended in an amount of 0.02 to 5 parts by weight with respect to 100 parts by weight of the resin component constituting the film, and a polyvinyl alcohol resin is further added to 100 parts by weight of the resin component constituting the film. Chemical-resistant polyolefin agricultural film characterized in that the total amount of inorganic heat-retaining agents is 1 to 15 parts by weight, and the ratio of polyvinyl alcohol resin and inorganic heat-retaining agent is 1/9 to 9/1 .   Polyvinyl alcohol-based resin has an α-olefin content of 3 to 30 carbon atoms of 0.5 to 20 mol%, a vinyl acetate component has a saponification degree of 60 to 99.9 mol%, and a polymerization degree of 50 to 50,000. The chemically resistant polyolefin-based agricultural film according to claim 1, which is a saponified product of an α-olefin-vinyl acetate copolymer. 3. The hindered amine light stabilizer has at least two piperidine ring structures represented by the following formula (1) and has an average molecular weight of 1000 or more. Chemical-resistant polyolefin agricultural film.

(1)
(R represents a functional group or compound (including oligomer and polymer) having 1 or more carbon atoms and containing at least one methylene group.)   The chemical resistance according to any one of claims 1 to 3, wherein the inorganic heat insulating agent contains at least one selected from the group consisting of hydrotalcites and lithium aluminum composite hydroxide. Polyolefin agricultural film.