JP6207201B2 - Agricultural film - Google Patents

Description

  The present invention relates to an agricultural film having excellent total light transmittance and light diffusing performance, as well as excellent rubbing strength and tear strength.

  In the cultivation of soft vegetables (for example, spinach, Japanese mustard spinach), it is necessary to incorporate a large amount of scattered light while sufficiently transmitting the amount of light from sunlight and suppressing transmission of direct light. This is due to the following reason. First, problems such as poor growth of crops occur when the amount of light from sunlight is insufficient. On the other hand, if there is a lot of direct light, the temperature inside the house will rise, and when the soft vegetables are cultivated, problems such as leaf burning (a phenomenon in which the temperature is suddenly applied to the leaves and the leaves are burned) occur. Or, there was a problem that a shadow was generated in the house or tunnel, resulting in a difference in growth. In order to solve these problems, a technique for adding an inorganic substance to a multilayer film is disclosed. (Patent Document 1)

  On the other hand, traditionally, the mica wire is used to fix the agricultural film so that the agricultural film is not turned by the wind. However, the strong film rubs the agricultural film and the mica wire and damages the agricultural film. There was a problem to do.

JP 2012-70707 A

However, when an inorganic substance is added as in the agricultural film described in Patent Document 1, in addition to the decrease in transparency and diffusion performance, there is a risk that the rubbing strength and tear strength also decrease.
An object of the present invention is to provide an agricultural film which is excellent in transparency and light diffusion performance, and excellent in rubbing strength and tensile strength.

As a result of intensive studies, the present inventors have
A layer (A) containing linear low density polyethylene;
A layer (B) containing an ethylene-vinyl acetate copolymer disposed above or above the layer (A);
An agricultural film comprising a polyethylene-containing layer (C) disposed above or above the layer (B),
The layer (A), the layer (B) or both contain mica,
An agricultural film in which the average particle diameter of the mica is in the range of 5 to 40 μm, and the content of mica is in the range of 0.3 to 100% by weight with respect to the entire agricultural film;
As a result of further research, the present invention has been completed.

The present invention includes the following aspects.
Item 1. A layer (A) containing linear low density polyethylene;
A layer (B) containing an ethylene-vinyl acetate copolymer disposed above or above the layer (A);
An agricultural film comprising a polyethylene-containing layer (C) disposed above or above the layer (B),
The layer (A), the layer (B) or both contain mica,
An agricultural film in which the average particle diameter of the mica is in the range of 5 to 40 μm, and the content of mica is in the range of 0.3 to 100% by weight with respect to the entire agricultural film.
Item 2.
The agricultural film according to claim 1, wherein the content of the linear low-density polyethylene with respect to the whole synthetic resin contained in the layer (A) is in the range of 60 to 100% by weight.

  Since the agricultural film of the present invention is excellent in transparency and diffusion performance, and is excellent in rubbing strength and tear strength, it can be used as an agricultural film for a long period of time even in harsh outdoor environments exposed to strong winds.

It is sectional drawing which shows the outline | summary of the one aspect | mode of the agricultural film of this invention.

[Layer (A)]
Layer (A) contains linear low density polyethylene.

  In the agricultural film of the present invention, the layer (A) has excellent abrasion strength and tear strength by containing linear low-density polyethylene.

  Linear low density polyethylene is obtained by copolymerizing ethylene and α-olefin using a single-site catalyst such as Ziegler catalyst or metallocene catalyst, and adjusting the type and amount of α-olefin. The density range can be controlled.

  Examples of the α-olefin include propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-heptene and 1-octene. The α-olefins may be used alone or in combination of two or more.

  The layer (A) may contain a synthetic resin other than the linear low-density polyethylene, and examples of the synthetic resin include ethylene resins other than the linear low-density polyethylene. As other ethylene resin, for example, low density polyethylene is preferable.

If the content of the linear low density polyethylene in the layer (A) is too low, the tear strength and rubbing strength of the agricultural film may be lowered. Therefore, the content of the linear low-density polyethylene with respect to the entire synthetic resin contained in the layer (A) is preferably in the range of 60 to 100% by weight, more preferably 65% by weight or more. Preferably it is 70 weight% or more.
The layer (A) preferably contains only linear low density polyethylene as a synthetic resin forming the layer structure.

The density of the linear low density polyethylene used in layer (A) is preferably from 0.890~0.945g / cm ^3, more preferably 0.895~0.925g / cm ^3.
If the density is too low, the rubbing strength of the layer (A) and thus the agricultural film may be insufficient, or a blocking (fusion) phenomenon may occur when folded and stored. On the other hand, if the density is too high, the layer (A) and thus the agricultural film become too hard, and the rubbing strength of the agricultural film may be reduced.

  In this specification, the density of synthetic resin (eg, linear low density polyethylene, ethylene-vinyl acetate copolymer (EVA), polyethylene) is the density and specific gravity of plastic-non-foamed plastic. It means a value measured according to “Measurement Method”.

The melt flow rate (MFR) of the linear low density polyethylene used for the layer (A) is preferably 0.3 to 3.0 g / 10 minutes, and more preferably 0.8 to 3 g / 10 minutes.
If the MFR is too small, the film formability of the layer (A) may be reduced. If the MFR is too large, the rubbing strength of the layer (A) and thus the agricultural film may be reduced.

  In this specification, the MFR of a synthetic resin (eg, linear low density polyethylene, ethylene-vinyl acetate copolymer (EVA), polyethylene) is JIS K7210 “plastic-thermoplastic melt mass flow rate and It means the value of the melt mass flow rate measured under the conditions of a temperature of 190 ° C. and a load of 21.18 N in accordance with “Test method for melt volume flow rate”.

The linear low density polyethylene is preferably
The density is in the range of 0.890 to 0.945 g / cm ³ and the melt flow rate is 0.3 to 3.0 g / 10 minutes.

  Layer (A) preferably contains mica. The mica will be described later.

  The thickness of the layer (A) is preferably in the range of 4.5 to 45.0 μm, more preferably in the range of 7.5 to 37.5 μm. If the thickness is too thin, the tear strength may be reduced. On the other hand, if the thickness is too thick, the transparency may be reduced.

[Layer (B)]
The layer (B) is disposed on or above the layer (A) and contains an ethylene-vinyl acetate copolymer.
The layer (B) preferably contains only an ethylene-vinyl acetate copolymer as a synthetic resin forming the layer structure.
The melt flow rate of the ethylene-vinyl acetate copolymer used for the layer (B) is preferably in the range of 0.3 to 3.0 g / 10 min.

The vinyl acetate content of the ethylene-vinyl acetate copolymer used for the layer (B) is preferably in the range of 4 to 30% by weight, more preferably in the range of 5 to 20% by weight.
If the vinyl acetate content is too low, the tear strength of the agricultural film may be reduced. On the other hand, if the vinyl acetate content is too high, the rubbing strength of the agricultural film may be reduced.

Ethylene used in the layer (B) - the density of the vinyl acetate copolymer is preferably in the range of 0.900~0.950g / cm ^3, more preferably of 0.920~0.945g / cm ³ Within range.
If the density is too low, the tear strength may be reduced. On the other hand, if the density is too high, the rubbing strength of the agricultural film may be reduced.

The melt flow rate (MFR) of the ethylene-vinyl acetate copolymer used for the layer (B) is preferably in the range of 0.3 to 3.0 g / 10 min, more preferably 0.8 to 2 g / Within 10 minutes.
If the MFR is too small, the film formation stability of the layer (B) may be reduced. On the other hand, if the MFR is too large, the tear strength of the layer (B) and thus the agricultural film may be reduced.

  Layer (B) preferably contains mica. The mica will be described later.

  The thickness of the layer (B) is preferably in the range of 19.5 to 195.0 μm, more preferably in the range of 32.5 to 162.5 μm. If the thickness is too thin, the tear strength may be reduced. On the other hand, if the thickness is too thick, the transparency may be reduced.

[Layer (C)]
The layer (C) is arranged on or above the layer (B) and contains polyethylene.
The layer (C) preferably contains only polyethylene as a synthetic resin forming the layer structure.
Examples of the polyethylene used for the layer (C) include low density polyethylene, medium density polyethylene, and linear low density polyethylene. Polyethylene may be used independently or 2 or more types may be used together.

  Of these polyethylenes, linear low density polyethylene is preferred. According to the linear low density polyethylene, it is possible to impart excellent abrasion strength and tear strength to the agricultural film.

  As linear low density polyethylene, the thing similar to what was described about the layer (A) can be used.

  The polyethylene used for the layer (C) may be a combination of linear low density polyethylene and other polyethylene. As other polyethylene, for example, low density polyethylene is preferable.

If the content of the linear low density polyethylene in the polyethylene used for the layer (C) is too low, the tear strength and rubbing strength of the agricultural film may be lowered. Therefore, the content is preferably 85% by weight or more, and it is more preferable that the polyethylene consists only of linear low density polyethylene.
Density polyethylene used in layer (C) is preferably from 0.890~0.945g / cm ^3, more preferably 0.895~0.925g / cm ^3.
If the density is too low, the rubbing strength of the layer (C) and thus the agricultural film may be insufficient, or a blocking (fusion) phenomenon may occur when folded and stored. On the other hand, if the density is too high, the layer (C) and thus the agricultural film may become too hard, and the tear strength of the agricultural film may be reduced.

The melt flow rate (MFR) of polyethylene is preferably 0.3 to 3.0 g / 10 minutes, and more preferably 0.8 to 3 g / 10 minutes.
If the MFR is too small, the film formability of the layer (C) may be reduced. On the other hand, if the MFR is too large, the tear strength and rubbing strength of the layer (C) and thus the agricultural film may be reduced.

  The thickness of the layer (C) is preferably in the range of 6.0 to 50.0 μm, more preferably in the range of 10.0 to 50.0 μm. If the thickness is too thin, the tear strength may be reduced. On the other hand, if the thickness is too thick, the transparency may be reduced.

[mica]
The agricultural film of the present invention has moderate light transmittance and scattering characteristics and exhibits rubbing strength by containing mica in the layer (A), the layer (B) or both. it can.
The type of mica is not limited and may be natural mica such as muscovite, biotite, sericite, or synthetic mica, but muscovite and sericite are preferably used from the viewpoint of transparency.
The average particle diameter of mica is 5 in that both the scattered light transmittance and the total light transmittance are good, and the mechanical strength such as tear strength and break strength of the agricultural film can be prevented. -40 μm is preferable, 8-30 μm is more preferable, and 15-20 μm is particularly preferable.

  The content of mica with respect to the entire agricultural film is limited to 0.3 to 10 parts by weight. Thereby, both the scattered light transmittance and the total light transmittance can be made good, and the mechanical strength such as tear strength and breaking strength of the agricultural film can be prevented from being lowered.

Each layer of the agricultural film of the present invention contains a hindered amine light stabilizer, a heat stabilizer, an antioxidant, an ultraviolet absorber, a lubricant, a pigment, and the like as required, as long as the physical properties are not significantly impaired. May be.
Any conventionally known hindered amine light stabilizer can be used. Specific examples thereof include dimethyl succinate-1- (2-hydroxyethyl) -4-hydroxy-2,2,6,6-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]} and the like. . These may be used alone or in combination of two or more.

As the heat stabilizer, any conventionally known one can be used. Specific examples thereof include chelators such as metal salts of carboxylic acids, phenolic antioxidants, and organic phosphites. These may be used alone or in combination of two or more.
Any conventionally known antioxidant can be used as the antioxidant. Many antioxidants usually have the effect as the heat stabilizer. Specific examples thereof include chelators such as metal salts of carboxylic acids, phenolic antioxidants, and organic phosphites. These may be used alone or in combination of two or more.

Any conventionally known ultraviolet absorber can be used. Specific examples thereof include benzophenone-based UV absorbers, benzotriazole-based UV absorbers, salicylic acid ester-based UV absorbers, and cyanoacrylate-based UV absorbers. These may be used alone or in combination of two or more. Examples of the benzophenone ultraviolet absorber include 2,4-dihydroxybenzophenone, 2-hydroxy-4-octoxybenzophenone, 2-hydroxy-4-dodecyloxybenzophenone, 2,2′-dihydroxy-4-methoxybenzophenone, 2 , 2′-hydroxy-4,4′-dimethoxybenzophenone, 2-hydroxy-4-methoxy-5-sulfobenzophenone, and the like. Examples of the benzotriazole ultraviolet absorber include 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 Chlorobenzotriazole, 2- (2′-hydroxy-3 ′, 5′-di-tert-amylphenyl).
Any conventionally known lubricant can be used as the lubricant. Specific examples thereof include saturated fatty acid amides such as stearic acid amide, unsaturated fatty acid amides such as erucic acid amide and oleic acid amide, and bisamides such as ethylene bis stearic acid amide. These may be used alone or in combination of two or more.

  If the thickness of the light diffusible agricultural film of the present invention is too thin, the mechanical strength may be reduced. Conversely, if it is too thick, cutting, joining, stretching work and the like become difficult, and handling properties are reduced. There is a fear. Therefore, the thickness is preferably in the range of 30 to 300 μm, more preferably in the range of 50 to 250 μm.

The agricultural film of the present invention has one or more layers other than the layer (A), the layer (B), and the layer (C) as long as the properties of the agricultural film of the present invention are not significantly impaired. May be simply referred to as other layers). The other layer may be disposed at any position on the agricultural film of the present invention.
FIG. 1 shows one embodiment of the agricultural film of the present invention.
In FIG. 1, the agricultural film 10 of the present invention is
A layer (A) 13 containing linear low density polyethylene;
A layer (B) 12 containing an ethylene-vinyl acetate copolymer disposed on the layer (A);
And a layer (C) 11 containing polyethylene disposed on the layer (B).

[Production method]
The agricultural film of the present invention may be produced using a conventionally known laminated film production method such as a multilayer inflation method, a multilayer T-die method, a multilayer laminate method, or a calendar method.

Especially, as a manufacturing method of a laminated body, after obtaining the resin composition of a molten state by melt-kneading each component which comprises each layer in a separate extruder, it is the resin composition of a molten state from each extruder. Is supplied to a circular multilayer die, and a molten resin composition is coextruded from the circular multilayer die to form a cylindrical film, and compressed air is supplied from the center of the circular multilayer die. A multilayer inflation method is preferred in which an agricultural film is produced by stretching an extruded cylindrical film in the circumferential direction.

In the case of forming a droplet layer on one surface of the layer (C), preferably, after forming a laminate comprising the layer (A), the layer (B), and the layer (C), the droplet is dropped using the droplet agent. Form a layer.
As a method for preparing the dropping agent, for example, an aqueous medium, a binder resin, colloidal silica, and colloidal alumina are mixed, and if necessary, other additives are added to obtain a mixed solution. A method for obtaining a dropping agent by stirring is mentioned. By such a method, a dropping agent in which colloidal silica and colloidal alumina are dispersed in an aqueous medium and a binder resin can be obtained. Stirring of the mixed solution can be performed using a known method such as a homogenizer.

  And as a method of forming a droplet layer on one side of layer (C) of a layered product, it is not particularly limited, for example, a droplet agent is a roll coating method such as a gravure coater, a barcode method, a dip coating method, Examples of the method include a method in which the film is applied to one surface of the inner layer (C) of the agricultural film and then dried by a coating method such as a spray method or a brush coating method.

  As a method for drying the liquid drop applied to one surface of the layer (C), either a natural drying method or a forced drying method may be used. As the forced drying method, for example, a heat drying method using hot air, infrared rays, far infrared rays, or the like is used.

  On one side of the layer (C), corona treatment, plasma treatment, ozone treatment, flame treatment, chemical conversion treatment, primer treatment, etc., in order to improve the coating properties of the anti-fogging droplet before applying the droplet The surface treatment may be performed.

The agricultural film of the present invention can be used in the same manner as a conventional agricultural film, and is excellent in transparency and light diffusion performance, and is excellent in rubbing strength and tear strength. It can be used for a long time as an agricultural film even in harsh environments.
The agricultural film of the present invention has a layer (A) side facing outward (side exposed to sunlight or wind more strongly) and a layer (C) side facing inward (for example, when used for plant cultivation) For the plant side).

  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
1. Preparation of resin composition for forming layer (A) Linear low-density polyethylene (1) (density 0.920 g / cm ³ , MFR 0.8 g / 10 min, trade name “Elite 5100” manufactured by Dow Chemical Co.) 100 parts by weight , White mica (Yamaguchi Mica Co., Ltd., trade name “Yamaguchi Mica A-21 average particle size 22 μm” 4 parts by weight, light stabilizer (HALS: BASF Japan, trade name “TINUVIN 783”) 0.7 parts by weight, The molten layer (A) forming resin composition was obtained by supplying to an extruder and melt-kneading.

2. Preparation of resin composition for forming layer (B) Ethylene-vinyl acetate copolymer (3) (vinyl acetate content 20 wt%, MFR 1.5 g / 10 min, density 0.941, trade name “Ultrasen” manufactured by Tosoh Corporation 631 ”density 0.941) 100 parts by weight, infrared absorber (trade name“ DHT-4A ”manufactured by Kyowa Chemical Industry Co., Ltd.) 7.5 parts by weight, hindered amine light stabilizer (BASF Japan, trade name“ TINUVIN 783 ”) ) 0.7 parts by weight was supplied to the second extruder and melt kneaded to obtain a molten layer (B) forming resin composition.

3. Preparation of resin composition for forming layer (C) Linear low density polyethylene (1) (density 0.920 g / cm ³ , MFR 0.8 g / 10 min, Dow Chemical Company, trade name “Elite 5100”) 100 parts by weight , 0.7 parts by weight of a light stabilizer (HALS: BASF Japan, trade name “TINUVIN783”) is supplied to a third extruder and melt-kneaded to obtain a resin composition for forming a molten layer (C) Obtained.

4). Formation of Laminate Next, the molten resin composition is supplied from each of the first to third extruders to the circular multilayer die, and the molten resin composition is supplied from the circular multilayer die to the layer (A). , Layer (B), and layer (C) are coextruded to form a laminated and integrated state in this order to obtain a cylindrical film and compressed air from the center of the circular multilayer die. After supplying and stretching the coextruded cylindrical film in the circumferential direction, the cylindrical film is cooled with cooling air, and the cylindrical film is cut open and wound up, whereby the layer (A) ( A laminate in which the thickness (22.5 μm), the layer (B) (thickness 97.5 μm), and the layer (C) (thickness 30.0 μm) were laminated and integrated in this order was obtained, that is, an agricultural film. .

(Examples 2 to 11, Comparative Examples 1 to 9 and 11 to 13)
Each agricultural film was obtained in the same manner as in Example 1 with the blending ratio (unit: parts by weight) shown in Table 3.

  About the following items, the agricultural film of the said Example and the comparative example was evaluated with the following evaluation methods. The results are shown in Table 3 (Table 3-1 and Table 3-2).

[Evaluation method]
(1) Total light transmittance Total light transmittance was measured by a method based on JIS K7105.
(2) Diffuse transmittance The total light transmittance and haze were measured by a method based on JIS K7105, and calculated by the following formula.
Diffuse transmittance = (total light transmittance × haze) / 100
Equipment used: Nippon Denshoku Industries Co., Ltd., MDH2000
(3) Elastic modulus It measured by the method based on JISK7127.
Equipment used: Tensile tester, Shimadzu Corporation, AGS-J
(4) Tear strength It measured by the method based on JISK7128-2.
Equipment used: Elmendorf Tear Strength Tester, Toyo Seiki Seisakusho Co., Ltd., Elmendorf D-type (5) Friction Strength Friction with a load of 20 cm of mica wire (Ishimoto Maoran: product name “Mica wire (black))” on the test stand A film piece of 1 cm ² was attached to the child part, the film piece was rubbed against the mica wire under the conditions of a reciprocating distance of 120 mm, a reciprocating speed of 30 cpm, and a load of 2 N, and the number of reciprocations until the hole was formed in the film was counted.
Equipment used: Gakushin Abrasion Tester, Toyo Seiki Co., Ltd., Gakushin Abrasion Tester S

[Pass / fail judgment]
The pass / fail ratio determination of each evaluation item is as follows.

[material]
The materials used are as follows. In the table, VA is the vinyl acetate content.

Agricultural film 10,
Layer containing polyethylene (C) 11
Layer containing ethylene-vinyl acetate copolymer (B) 12
Layer containing linear low density polyethylene (A) 13

Claims (2)

A layer (A) containing linear low density polyethylene;
A layer (B) containing an ethylene-vinyl acetate copolymer disposed above or above the layer (A);
An agricultural film comprising a polyethylene-containing layer (C) disposed above or above the layer (B),
The layer (A) or both the layer (A) and the layer (B) contain mica;
The average particle diameter of mica is within the range of 5 to 40 m, and the content of mica relative to the total agricultural film is Ri der range of 0.3 to 10 wt%,
The agricultural film , wherein the content of the mica in the layer (A) is 7 parts by weight or less with respect to 100 parts by weight of the synthetic resin contained in the layer (A) . The agricultural film according to claim 1, wherein the content of the linear low-density polyethylene with respect to the whole synthetic resin contained in the layer (A) is in the range of 60 to 100% by weight.