JP2006143965A - An ethylene-vinyl acetate copolymer composition for agricultural coating film and an agricultural coating film comprising the same. - Google Patents

Abstract

An ethylene-vinyl acetate copolymer composition for agricultural coating film having excellent heat retention, transparency and toughness, and an agricultural coating film comprising the same.
A melt flow rate measured in accordance with JIS K6924-1 (1997) is 0.3 to 20 g / 10 min, and a vinyl acetate residue content measured in accordance with JIS K6924-1 (1997) is 3 to 3. 100 parts by weight of a mixture having a blending weight ratio of 30% by weight of the ethylene-vinyl acetate copolymer (A) and the layered clay mineral (B) in the range of (A) / (B) = 98/2 to 50/50 An ethylene-vinyl acetate copolymer composition for agricultural coating film and an agricultural coating film comprising the same, comprising 0 to 50 parts by weight of modified polyolefin resin (C).
[Selection figure] None

Description

  The present invention relates to an ethylene-vinyl acetate copolymer composition for agricultural coating films, and more specifically, an ethylene-vinyl acetate copolymer for agricultural coating films having excellent heat retention, transparency and toughness required for agricultural coating films. The present invention relates to a polymer composition and an agricultural coating film comprising the same.

  Agricultural coating films are used for agriculture such as house cultivation and tunnel cultivation, and polyolefin resins such as vinyl chloride, polyethylene, and ethylene-vinyl acetate copolymer are used. Among them, agricultural coating films using ethylene-vinyl acetate copolymer composition as the main raw material have little decrease in mechanical strength over time, can be used for a long period of time for multiple years, and are free of toxic gases such as dioxins during incineration. Since it does not occur and film processing is easy, it is widely used as an agricultural coating film.

  However, compared with agricultural coating films using vinyl chloride, agricultural coating films made mainly of an ethylene-vinyl acetate copolymer composition are inferior in heat retention and transparency, and improvements have been demanded. It was.

  In order to obtain good heat retention, infrared rays radiated from the ground or plants heated by sunlight in the daytime or boilers, etc. must pass through the agricultural cover film and be dissipated outside the house or tunnel. It is important to prevent

  As an index of general heat retention of agricultural coated films, the infrared absorption rate of the film is used, and a film having a high absorption rate is said to have good heat retention properties. In addition, the infrared absorptivity of the film is obtained by multiplying the absorptivity corresponding to each wavelength of the film obtained by the infrared spectrophotometer by the spectral radiant divergence of each wavelength obtained by Planck's radiation law, It can be expressed by a heat retention index which is a ratio to the value of the spectral radiant divergence.

  The ethylene-vinyl acetate copolymer composition has good transparency, but if a heat retention agent such as an inorganic filler is added for the purpose of improving heat retention, the transparency becomes poor and both heat retention and transparency are achieved. It is necessary to select a heat insulating agent that does not adversely affect transparency.

  Conventionally, by adding hydrotalcite, silica, zeolite, kaolin, glass powder, etc. as a substance that absorbs and reflects infrared rays on agricultural coating films, there is a method for preventing infrared transmission and dissipation and improving heat retention. It has been proposed (see, for example, Patent Document 1).

Japanese Examined Patent Publication No. 62-031744

  However, in the method described in Patent Document 1, sufficient heat retention cannot be obtained, and when heat retention equal to that of an agricultural coating film using vinyl chloride is obtained by adding a large amount of a heat retention agent to the film. On the contrary, there was a problem that transparency was hindered.

  In order to solve the above problems, an object of the present invention is to provide an ethylene-vinyl acetate copolymer composition for an agricultural coating film that is excellent in heat retention, transparency, and toughness required for an agricultural coating film, and an agricultural coating film comprising the same. Is intended to provide.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors were excellent in heat retention, transparency and toughness by blending a specific proportion of layered clay mineral with a specific ethylene-vinyl acetate copolymer. It has been found that an ethylene-vinyl acetate copolymer composition for agricultural coating films can be obtained, and the present invention has been completed.

  That is, the present invention has a melt flow rate measured in accordance with JIS K6924-1 (1997) of 0.3 to 20 g / 10 min, and a vinyl acetate residue content measured in accordance with JIS K6924-1 (1997). Mixture 100 in which the blending weight ratio of the ethylene-vinyl acetate copolymer (A) and the layered clay mineral (B) of 3 to 30% by weight is in the range of (A) / (B) = 98/2 to 50/50 The present invention relates to an ethylene-vinyl acetate copolymer composition for agricultural coating films and an agricultural coating film comprising the same, comprising 0 to 50 parts by weight of modified polyolefin resin (C) with respect to parts by weight.

  Hereinafter, the present invention will be described in detail.

  The ethylene-vinyl acetate copolymer composition for agricultural coating film of the present invention comprises a specific amount of modified polyolefin with respect to a mixture comprising a specific proportion of ethylene-vinyl acetate copolymer (A) and layered clay mineral (B). It is an ethylene-vinyl acetate copolymer composition for agricultural coating films formed by blending a resin.

  The melt flow rate (MFR) measured in accordance with JIS K6924-1 (1997) of the ethylene-vinyl acetate copolymer (A) used in the present invention is 0.3 to 20 g / 10 min, preferably 0.5. ~ 15 g / 10 min. When the MFR is less than 0.3 g / 10 min, the melt viscosity of the ethylene-vinyl acetate copolymer composition for agricultural coating film is high and the moldability is inferior, which is not preferable. In addition, when the MFR exceeds 20 g / 10 min, the melt tension of the ethylene-vinyl acetate copolymer composition for agricultural coating film is small, and not only can the film be stably formed at the time of film formation, but also the impact strength when the film is formed. Is not preferred because there is a risk of damage.

  The vinyl acetate residue content measured according to JIS K6924-1 (1997) of the ethylene-vinyl acetate copolymer (A) used in the present invention is 3 to 30% by weight, preferably 5 to 25% by weight. is there. When the vinyl acetate residue content is less than 3% by weight, the heat retaining property, which is an essential performance when the ethylene-vinyl acetate copolymer composition for agricultural coating film is used as a film, cannot be obtained sufficiently. In addition, when the vinyl acetate residue content exceeds 30% by weight, when the ethylene-vinyl acetate copolymer composition for agricultural coating film is used as a film, the film tends to be stretched by heat such as sunlight, which is not preferable.

  The ethylene-vinyl acetate copolymer (A) used in the present invention can be obtained by a radical polymerization method by a high pressure method which is a general polymerization method.

  The layered clay mineral (B) used in the present invention is not particularly limited and may be any layered clay mineral, and among them, a layered silicate mineral made of magnesium silicate or aluminum silicate is preferable. Specific examples of the layered clay mineral include, for example, montmorillonite, nontronite, beidellite, hectorite, saponite, stevensite, soconite belonging to the scumite group; muscovite, paragonite, phlogopite, biotite belonging to the mica group, Illite, paragonite, bramarite, lepidrite; kaolinite, hyrosite, dickite, chrysotile, amesite, lizardite; pyrophyllite, talc, pyrophyllite; vermiculite, permiculite; brittle mica Margarite, clintonite, anandite; donbasite, kukeite, clinochlore belonging to the chlorite group, etc., among which muscovite, montmorillonite, saponite, hectorite are preferred, especially white Mother preferred. These may be natural or synthesized. Moreover, this layered clay mineral can be used 1 type, or 2 or more types.

  As for the size of the layered clay mineral (B) used in the present invention, the length of one piece is preferably 1 μm or less and the layer thickness is preferably 0.001 to 0.1 μm. When a layered clay mineral is used, it does not cause irregular reflection of light that occurs when a spherical inorganic filler is used. As a result, since the amount which can be added can be increased, it is excellent also in heat retention.

  As the layered clay mineral (B) used in the present invention, a general commercially available product can be used. For example, muscovite (trade name ME-100) manufactured by Corp Chemical Co., Ltd .; manufactured by Kunimine Industries Co., Ltd. Montmorillonite (trade name Kunipia F), Cloisite montmorillonite (trade names Cloisite 15A, Cloisite 20A), SUD Chemie montmorillonite (trade name NanofilSE3000); Hectorite (trade name Laponite RD) manufactured by Shin Kasei Co., Ltd. can be used.

  The blending weight ratio (A) / (B) of the ethylene-vinyl acetate copolymer (A) and the layered clay mineral (B) used in the present invention is in the range of 98/2 to 50/50, preferably 95. / 5 to 70/30. When the blending ratio of the layered clay mineral (B) is less than 2% by weight, it is not preferable because sufficient heat retention cannot be obtained when the ethylene-vinyl acetate copolymer composition for agricultural coating film is used as a film. On the other hand, when the blending ratio of the layered clay mineral (B) is more than 50% by weight, the transparency and toughness are inferior when the ethylene-vinyl acetate copolymer composition for agricultural coating film is used as a film.

  The modified polyolefin resin (C) used in the present invention may be any modified polyolefin resin, and among them, a graft-modified polyolefin resin obtained by blending an organic acid with a polyolefin resin is preferable. In this case, the blending amount of the organic acid is preferably 0.05 to 15 parts by weight with respect to 100 parts by weight of the polyolefin resin.

  Examples of the polyolefin resin to be used for modification include low density polyethylene, high density polyethylene, ethylene / α-olefin copolymer, ethylene-vinyl acetate copolymer, etc., and these are used alone or in combination of two or more. It is also possible. Among these polyolefin resins, an ethylene-vinyl acetate copolymer is preferable because it is excellent in transparency, heat retention and toughness when an ethylene-vinyl acetate copolymer composition for agricultural coating films is used as a film.

  Examples of the organic acid to be used for modification include unsaturated carboxylic acid represented by maleic acid, maleic anhydride, acrylic acid, acrylic acid derivatives, etc. Among them, maleic anhydride is inexpensive and has good workability. Is preferred.

  As a modification method of the organic acid and the polyolefin resin in obtaining the modified polyolefin resin, any method can be used as long as the polyolefin resin can be modified. Among them, the organic acid and the polyolefin resin are melt-kneaded. The method is preferably used. As the melt kneading method, for example, an organic acid, a polyolefin resin, and a radical generator are charged into a single screw extruder, a twin screw kneader, a Banbury mixer, etc., and kneaded for about 1 to 20 minutes while heating to a temperature of 120 to 230 ° C. Can be used.

  As the radical generator used in the melt-kneading method, it is preferable to use a peroxide having a decomposition temperature of 100 to 250 ° C. for obtaining a half-life of 1 minute. For example, t-hexylperoxyneodecanoate, t-butylperoxypivalate, dibenzoyl peroxide, 1,1-di (t-butylperoxy) cyclohexane, 2,5-dimethyl-2,5-di (t- Mention may be made of peroxides such as (butylperoxy) hexyne, di-t-butyl peroxide, 1,1,3,3-tetramethylbutyl hydroperoxide.

  As the modified polyolefin resin (C) used in the present invention, a general commercially available product can be used. For example, a modified polyolefin resin (trade name key polymer NC-1200) manufactured by Rohm and Hass, Mitsui Chemicals, Inc. Examples thereof include modified polyolefin resins such as manufactured modified polyolefin resins (trade name Admer VF600).

  The blending ratio of the modified polyolefin resin (C) used in the present invention is the modified polyolefin resin (C) 0 with respect to 100 parts by weight of the mixture of the ethylene-vinyl acetate copolymer (A) and the layered clay mineral (B). -50 parts by weight, preferably 0-30 parts by weight, more preferably 0-15 parts by weight. When the ratio of the modified polyolefin resin (C) is more than 50 parts by weight, the toughness is inferior when the ethylene-vinyl acetate copolymer composition for agricultural coating film is used as a film.

  The ethylene-vinyl acetate copolymer composition for agricultural coating film of the present invention comprises an antioxidant, an ultraviolet absorber, a light stabilizer, an antistatic agent, an antifogging agent, an antifogging agent, a lubricant, and an antiblocking as necessary. You may contain the various additive currently used in the technical field of agricultural covering films, such as an agent.

  There is no restriction | limiting in particular as antioxidant, What is generally known as antioxidant can be used, for example, pentaerythritol tetrakis (3- (3,5-di-t-butyl-4-hydroxy). Phenyl) propionate), octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, 3,3 ′, 3 ″, 5,5 ′, 5 ″ -hexa-t-butyl -A, a ', a' '-(mesitylene-2,4,6-triyl) tri-p-cresol, 1,3,5-tris (3,5-di-t-butyl-4-hydroxybenzyl) Phenolic antioxidants such as -1,3,5-triazine-2,4,6 (1H, 3H, 5H) -trione; tris (2,4-di-t-butylphenyl) phosphite, bis (2 , 4-bis (1,1- Methylethyl-6-methylphenyl) ethyl ester phosphorous acid, tetrakis (2,4-di-t-butylphenyl) (1,1-biphenyl) -4,4′-diisobisphosphonite, bis (2, Phosphorus antioxidants such as 4-di-t-butylphenyl) pentaerythritol diphosphite; sulfur systems such as didodecyl-3,3′-thiodipropionate, dioctadecyl-3,3′-thiodipropionate Antioxidant; tris (2,4-di-t-butylphenyl) phosphite, tris (2-t-butyl-4- (3-t-butyl-4-hydroxy-5-methylphenylthio) -5 Phosphite antioxidants such as methylphenyl) phosphite; among others, pentaerythritol tetrakis (3- (3,5-di-t-butyl) 4-hydroxyphenyl) propionate) are preferred. These antioxidants can also be used singly or in combination of two or more kinds.

  There is no restriction | limiting in particular as an ultraviolet absorber used for this invention, What is generally known as an ultraviolet absorber can be used, for example, 2- (2H-benzotriazol-2-yl) -p- Cresol, 2- (2H-benzotriazol-2-yl) -4-6-bis (1-methyl-1-phenylethyl) phenol, 2- (5-chloro (2H) -benzotriazol-2-yl)- 4-methyl-6- (t-butyl) phenol, 2,4-di-t-butyl-6- (5-chlorobenzotriazol-2-yl) phenol, 2- (2H-benzotriazol-2-yl) -4,6-di-t-pentylphenol, 2- (2H-benzotriazol-2-yl) -4- (1,1,3,3-tetramethylbutyl) phenol, 2- (4,6- Gif Nyl-1,3,5-triazin-2-yl) -5-((hexyl) oxy) -phenol, octabenzene and the like, among which 2- (5-chloro (2H) -benzotriazole-2- Yl) -4-methyl-6- (t-butyl) phenol. These can be used alone or in combination of two or more.

  The light stabilizer used in the present invention is not particularly limited, and those generally known as light stabilizers can be used. For example, 2,4-di-t-butylphenyl-3,5- Di-t-butyl-4-hydroxybenzoate, dibutylamine, 1,3,5-triazine, N, N′-bis (2,2,6,6-tetramethyl-4-piperidyl-1,6-hexamethylene Polycondensate of diamine and N- (2,2,6,6-tetramethyl-4-piperidyl) butylamine, poly ((6- (1,1,3,3-tetramethylbutyl) amine-1,3 5-triazine-2,4-diyl) (2,2,6,6-tetramethyl-4-piperidyl) imino) hexamethylene ((2,2,6,6-tetramethyl-4-piperidyl) imino), Dimethyl succinate and 4-hydro Polymer of cis-2,2,6,6-tetramethyl-1-piperidineethanol, bis (1,2,2,6,6-pentamethyl-4-piperidyl) ((3,5-bis (1,1 -Dimethylethyl) -4-hydroxyphenyl) methyl) butyl malonate, bis (2,2,6,6-tetramethyl-4-piperidyl) zebacate and the like, among which 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), which may be used alone or in combination of two or more.

  The antistatic agent used in the present invention is not particularly limited, and those generally known as antistatic agents can be used. For example, fatty acid esters of nonionic polyhydric alcohols, ethylene of fatty alcohols Examples include oxide adducts, cationic primary amine salts, tertiary amines, anionic fatty alcohol sulfates, alkylbenzene sulfonates, amphoteric carboxylic acid derivatives, imidazoline derivatives, and the like. Alternatively, two or more types can be used in combination.

  The antifogging agent used in the present invention is not particularly limited, and those generally known as an antifogging agent can be used. For example, monoglycerides of fatty acid salt compounds, acetylated monoglycerides, organic acid monoglycerides, Examples include medium chain triglycerides, diglycerin fatty acid esters, tetraglycerin fatty acid esters, sorbitan fatty acid esters, inorganic compounds such as colloidal silica, alumina sol, and silicone oil. Of these, sorbitan fatty acid esters are preferred. These can be used alone or in combination of two or more.

  The anti-fogging agent used in the present invention is not particularly limited, and those generally known as anti-fogging agents can be used. For example, perfluoroalkyl acrylate compounds, perfluoroalkyl sulfonates, perfluoro Examples thereof include alkylcarboxylates, and among these, perfluoroalkyl acrylate compounds are preferred. These can be used alone or in combination of two or more.

  The lubricant used in the present invention is not particularly limited, and those generally known as lubricants can be used. For example, fatty acid monoamide lubricants such as lauric acid amide, palmitic acid amide, stearic acid amide, olein Acid amide, erucic acid amide; fatty acid bisamide-based lubricants such as ethylene bis stearic acid amide, ethylene bis oleic acid amide, ethylene biserucic acid amide, etc., which can be used alone or in combination of two or more It is.

  The anti-blocking agent used in the present invention is not particularly limited, and those generally known as anti-blocking agents can be used, which may be natural products or synthetic products, such as silica, talc, kaolin, mica. , Feldspar, diatomaceous earth, zeolite, calcium carbonate, clay, barium sulfate and the like, and these can be used alone or in combination of two or more.

  Moreover, inorganic compounds, such as a hydrotalcite, a zeolite, and glass powder, can be added to the ethylene-vinyl acetate copolymer composition for agricultural coating films of this invention in the range which does not impair this result.

  As the method for producing the ethylene-vinyl acetate copolymer composition for agricultural coating film of the present invention, any method can be used as long as the ethylene-vinyl acetate copolymer composition for agricultural coating film is obtained. For example, a method of melt kneading an ethylene-vinyl acetate copolymer (A), a layered clay mineral (B), a modified polyolefin resin (C) with a single screw extruder, a twin screw extruder, a roll, a kneader, a Banbury mixer, etc. Among them, the method of producing with a single screw extruder is preferable. When manufacturing with a single screw extruder, it is preferable to carry out at the temperature of 150-250 degreeC.

  By film-processing the ethylene-vinyl acetate copolymer composition for agricultural coating film of the present invention, an agricultural coating film is obtained. As the film processing method at that time, for example, a normal air-cooled inflation molding method, water cooling Known molding methods such as an inflation molding method and a cast molding method can be used, and among them, the cast molding method is preferable. Conditions for film processing by the cast molding method are preferably, for example, a processing temperature of 110 to 220 ° C., a take-up speed of 5 to 50 m / min, a cooling roll temperature of 20 to 50 ° C., and the thickness of the obtained film is 30 to 300 μm. The width of is preferably 0.5 to 15 m.

  Moreover, when setting it as an agricultural covering film, it is not restricted to a single layer film, It is also possible to set it as the laminated body which has an agricultural covering film of this invention at least 1 layer or more. As the resin film constituting the laminate at that time, for example, low density polyethylene, high density polyethylene, ethylene-vinyl acetate copolymer, ethylene / acrylic acid ester copolymer, ethylene / α-olefin copolymer, polypropylene, Examples include resin films made of resins such as ionomers, vinyl polymers, polyamides, polyesters, polyvinyl alcohols, and ethylene / vinyl alcohol copolymers. Specific laminates include, for example, first layer / second layer = low. Density polyethylene film / agricultural coating film of the present invention, first layer / second layer / third layer = low density polyethylene film / agricultural coating film of the present invention / ethylene-vinyl acetate copolymer film, and the like. Moreover, it is also possible to use an adhesive when making a laminated body.

  The agricultural coating film comprising the ethylene-vinyl acetate copolymer composition for agricultural coating film of the present invention can be suitably used for agricultural coating films for house cultivation, tunnel cultivation and the like.

  Agricultural coating film comprising the ethylene-vinyl acetate copolymer composition for agricultural coating film of the present invention is excellent in transparency, toughness, and heat retention, and thus is suitably used as an agricultural coating film, such as house cultivation and tunnel cultivation. It is useful for preventing cold damage and wind damage that hinder the growth of agricultural products.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further in detail, this invention is not limited to these Examples. The measurement method of each physical property and the evaluation method of performance are shown below. In addition, the reagent used for the Example used the commercial item unless there is a notice.

<Vinyl acetate residue content>
It measured based on JISK6924-1 (1997).

<Melt flow rate (MFR)>
According to JIS K6924-1 (1997), the measurement was performed at a test temperature of 190 ° C. and a test load of 21.18N.

<Transparency>
Transparency was measured according to JIS K7105 (1981), using a haze meter (manufactured by Nippon Denshoku Industries Co., Ltd., 300A), and the haze value was used as an index of transparency.

Criteria for transparency ○: When the haze value is 15% or less, the transparency is excellent.

    X: When the haze value is larger than 15%, the transparency is inferior.

<Heat retention>
For heat retention, infrared absorption was measured in the range of 400 to 4000 cm ⁻¹ using an infrared spectrophotometer (manufactured by Nicolet Instrument Corporation, IMPAX 410). The sum of products obtained by multiplying the infrared absorptance every 2 cm ⁻¹ in this measured value by the spectral radiant divergence (M _λ ) of each wave number obtained by Planck's radiation law, and the spectral radiant divergence per 2 cm ⁻¹ (M The ratio of the sum of [ _lambda] ) to the sum total was defined as a heat retention index (H), which was an index of heat retention.

Judgment criteria for heat retention ○: When the heat retention index is 75% or more, the heat retention property is excellent.

    X: When the heat retention index is less than 75%, the transparency is inferior.

The spectral radiant divergence (M _λ ) is expressed by the following formula (1), and the thermal insulation index (H) is expressed by the following formula (2).

Mλ = C1 / λ ⁵ · 1 / (e ^{C2 / λT} −1) (1)
[Where C1 is the first radiation constant, C2 is the second radiation constant, λ is the wavelength, and T is the absolute temperature]
λ _U λ _{U
H = Σ (M λ × IR} ) / ΣM λ (2)
λ = λ _L λ = λ _L
Wherein, IR infrared absorptivity at lambda, lambda _U is (corresponding to the wave number 400 cm ^-1) upper wavelength in the infrared absorption rate measuring range, lambda _L corresponding to the lower limit wavelength (wave number 4000 cm ^-1 in the infrared absorption rate measuring range ), Measured in steps of 2 cm ⁻¹ between λ _U and λ _L ]
<Mechanical properties (toughness)>
As toughness, in accordance with JIS K6922-2, a tensile tester (manufactured by Shimadzu Corporation, DCS-500) is used to perform a tensile test at a tensile speed of 300 m / min, and tensile elongation at break (%) is measured to measure the toughness. It was.

Judgment criteria for toughness: When the tensile elongation at break is 350% or more, the toughness is excellent.

    X: When the tensile elongation at break is less than 350%, the toughness is inferior.

Synthesis Example 1 (Synthesis of modified polyolefin resin)
One weight of maleic anhydride per 100 parts by weight of an ethylene-vinyl acetate copolymer (manufactured by Tosoh Corporation, Ultrasen 637) having an MFR of 8.0 g / 10 min and a vinyl acetate residue content of 20% by weight Part, 0.008 part by weight of peroxide 2,5-dimethyl-2,5-di (t-butylperoxy) hexyne (manufactured by NOF Corporation, perhexine 25B) at a temperature of 180 ° C. by a 50 mmφ single screw extruder And kneaded to obtain a graft-modified polyolefin resin (C).

Example 1
Ethylene-vinyl acetate copolymer (A) (Made by Tosoh Corporation, Ultrasen 631) having a MFR of 1.5 g / 10 min and a vinyl acetate residue content of 20% by weight, and muscovite as a layered clay mineral (B) 5 parts by weight of the modified polyolefin resin (C) synthesized in Synthesis Example 1 with respect to 100 parts by weight of the mixture having a blending weight ratio of 95/5 with Cope Chemical Co., Ltd. (ME-100), an antioxidant 0.2 parts by weight of pentaerythritol tetrakis (3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate) (manufactured by Ciba Specialty Chemical Co., Ltd., IRGANOX 1010) which is a phenolic antioxidant 2- (5-chloro (2H) -benzotriazol-2-yl) -4-methyl-6- (t-butyl) pheno as an ultraviolet absorber (Ciba Specialty Chemicals Co., Ltd., TINUVIN 326) 0.1 parts by weight, poly ((6- (1,1,3,3-tetramethylbutyl) amino-1,3,5-triazine as a light stabilizer) -2,4-diyl) (2,2,6,6-tetramethyl-4-piperidyl) imino) hexamethylene ((2,2,6,6-tetramethyl-4-piperidyl) imino) (Ciba Specialty)・ 0.5 parts by weight of CHEMASSORB944 manufactured by Chemicals Co., Ltd., 1.5 parts by weight of sorbitan fatty acid ester (manufactured by Riken Vitamin Co., Ltd., Riquemar S-300W) as an antifogging agent, and perfluoroalkyl acrylate compound as an antifogging agent (Daikin Kogyo Co., Ltd., Unidyne DS-403) 0.2 parts by weight of cast molding machine (Sumitomo Heavy Industries) Machine Modern Co., Ltd., T-die 350 mm, lip clearance 1 mm, air chamber type), a film having a thickness of 100 μm was obtained at an extruder temperature of 150 ° C. and a T-die temperature of 150 ° C.

  As a result of evaluating the obtained film, the film was excellent in heat retention, transparency and toughness, and was suitable for an agricultural coating film. The results are shown in Table 1.

Example 2
Except not mix | blending modified polyolefin resin (C), it shape | molded to the film similarly to Example 1, and evaluated. As a result, the film was excellent in heat retention, transparency and toughness, and was suitable for an agricultural coating film. The results are shown in Table 1.

Example 3
A film was formed in the same manner as in Example 1 except that an ethylene-vinyl acetate copolymer (A) (Made by Tosoh Corporation, Ultrasen 633) having an MFR of 20.0 g / 10 min and a vinyl acetate residue content of 20% by weight was used. Molded and evaluated. As a result, the film was excellent in heat retention, transparency and toughness, and was suitable for an agricultural coating film. The results are shown in Table 1.

Example 4
Using an ethylene-vinyl acetate copolymer (A) having an MFR of 1.5 g / 10 min and a vinyl acetate residue content of 15% by weight (Ultrasen 630, manufactured by Tosoh Corporation), the blending amount of the modified polyolefin resin (C) is 10 A film was formed and evaluated in the same manner as in Example 1 except that it was changed to parts by weight. As a result, the film was excellent in heat retention, transparency and toughness, and was suitable for an agricultural coating film. The results are shown in Table 1.

Example 5
Except for blending 20 parts by weight of the modified polyolefin resin (C) with respect to 100 parts by weight of the mixture in which the blending weight ratio of the ethylene-vinyl acetate copolymer (A) and the layered clay mineral (B) is 80/20. The film was molded and evaluated in the same manner as in Example 1. As a result, the film was excellent in heat retention, transparency and toughness, and was suitable for an agricultural coating film. The results are shown in Table 1.

Example 6
Except that the layered clay mineral (B) was montmorillonite (Kunimine Kogyo Co., Ltd., Kunipia F), it was molded into a film and evaluated in the same manner as in Example 1. As a result, the film was excellent in heat retention, transparency and toughness, and was suitable for an agricultural coating film. The results are shown in Table 1.

Example 7
Except that the layered clay mineral (B) was saponite (Kunimine Kogyo Co., Ltd., Smecton SA), it was molded into a film and evaluated in the same manner as in Example 1. As a result, the film was excellent in heat retention, transparency and toughness, and was suitable for an agricultural coating film. The results are shown in Table 1.

Example 8
Except that the layered clay mineral (B) was hectorite (manufactured by Toshin Kasei Co., Ltd., Laponite RD), it was molded into a film in the same manner as in Example 1 and evaluated. As a result, the film was excellent in heat retention, transparency and toughness, and was suitable for an agricultural coating film. The results are shown in Table 1.

Example 9
A film was formed in the same manner as in Example 1 except that an ethylene-vinyl acetate copolymer (A) (Made by Tosoh Corporation, Ultrasen 515) having an MFR of 2.5 g / 10 min and a vinyl acetate residue content of 6% by weight was used. Molded and evaluated. As a result, the film was excellent in heat retention, transparency and toughness, and was suitable for an agricultural coating film. The results are shown in Table 1.

Example 10
Except for blending 20 parts by weight of the modified polyolefin resin (C) with respect to 100 parts by weight of the mixture in which the blending weight ratio of the ethylene-vinyl acetate copolymer (A) and the layered clay mineral (B) is 65/35. The film was molded and evaluated in the same manner as in Example 1. As a result, the film was excellent in heat retention, transparency and toughness, and was suitable for an agricultural coating film. The results are shown in Table 1.

Comparative Example 1
Example 1 except that silica that is not a layered clay mineral (Nippile-75J, manufactured by Nippon Silica Kogyo Co., Ltd.) was used instead of the layered clay mineral (B) and the modified polyolefin resin (C) was not blended. Similarly, it was molded into a film and evaluated. As a result, since the layered clay mineral was not used, the film was inferior in transparency and heat retention and was not suitable for a film for agricultural coating. The results are shown in Table 2.

Comparative Example 2
A film was evaluated in the same manner as in Example 1 except that the amount of the modified polyolefin resin (C) was 60 parts by weight. As a result, there were many compounding of polyolefin resin, and this film was inferior toughness and was not suitable for the film for agricultural coating. The results are shown in Table 2.

Comparative Example 3
Except for blending 20 parts by weight of the modified polyolefin resin (C) with respect to 100 parts by weight of the mixture in which the blending weight ratio of the ethylene-vinyl acetate copolymer (A) and the layered clay mineral (B) is 40/60. The film was molded and evaluated in the same manner as in Example 1. As a result, the blending ratio of the ethylene-vinyl acetate copolymer (A) was small, and the film was inferior in transparency and toughness and was not suitable for an agricultural coating film. The results are shown in Table 2.

Comparative Example 4
Except that the blending amount of the ethylene vinyl acetate copolymer (A) was 100 parts by weight and the layered clay mineral (B) and the modified polyolefin resin (C) were not blended, the film was molded and evaluated in the same manner as in Example 1. Went. As a result, since the layered clay mineral was not used, the film was inferior in heat retention and not suitable for agricultural coating films. The results are shown in Table 2.

Claims (7)

The melt flow rate measured according to JIS K6924-1 (1997) is 0.3 to 20 g / 10 min, and the vinyl acetate residue content measured according to JIS K6924-1 (1997) is 3 to 30% by weight. For 100 parts by weight of a mixture in which the blending weight ratio of a certain ethylene-vinyl acetate copolymer (A) and layered clay mineral (B) is in the range of (A) / (B) = 98/2 to 50/50, An ethylene-vinyl acetate copolymer composition for agricultural coating films, comprising 0 to 50 parts by weight of a modified polyolefin resin (C). The ethylene-vinyl acetate copolymer for agricultural coating film according to claim 1, wherein the layered clay mineral (B) is at least one selected from the group consisting of muscovite, montmorillonite, saponite, and hectorite. Composition. The modified polyolefin resin (C) is a graft-modified polyolefin resin obtained by blending 0.05 to 15 parts by weight of an organic acid with respect to 100 parts by weight of the polyolefin resin. Ethylene-vinyl acetate copolymer composition for agricultural coating film. The polyolefin resin used for modification is at least one selected from the group consisting of low density polyethylene, high density polyethylene, ethylene / α-olefin copolymer, and ethylene-vinyl acetate copolymer. The ethylene-vinyl acetate copolymer composition for agricultural coating films described in 1. 4. The ethylene-vinyl acetate copolymer composition for agricultural coating film according to claim 3, wherein the organic acid used for modification is maleic anhydride. An agricultural covering film comprising the ethylene-vinyl acetate copolymer composition for agricultural covering film according to any one of claims 1 to 5. An agricultural covering film, which is a laminate having at least one agricultural covering film according to claim 6.