JP2014057524A - Agricultural film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an agricultural film capable of exhibiting excellent hygroscopicity.SOLUTION: The agricultural film of the present invention is characterized by comprising 100 pts.wt. of a thermoplastic resin and 1 to 15 pts.wt. of burnt alum. Such an agricultural film of the present invention highly suppresses reduction of mechanical strength and transparency while being given excellent hygroscopicity. Therefore, the agricultural film of the present invention can be suitably used in a cultivation facility for greenhouse cultivation or tunnel cultivation and protect a crop against growth deficiency due to high humidity or dryness by adjusting humidity inside the cultivation facility.

Description

  TECHNICAL FIELD The present invention relates to an agricultural film that is suitably used in a crop cultivation facility such as an agricultural house.

  Greenhouse cultivation using cultivation facilities with agricultural films such as house cultivation and tunnel cultivation is widely used as a cultivation means for supplying various crops such as vegetables, fruits and flowers to the market throughout the year.

  Agricultural films are required to have excellent mechanical strength in order to prevent the crops in the cultivation facility from being damaged by flying objects such as wind and rain, stones and dust. In addition, the agricultural film has excellent transparency in order to transmit sunlight from the outside with high transmittance and promote the growth of the crops in the cultivation facility by the transmitted light. It is also sought to do. Therefore, a thermoplastic resin film is generally used as an agricultural film that satisfies these requirements.

  However, the humidity inside the cultivation facility varies greatly according to changes in season and weather. Because the thermoplastic resin itself has low moisture permeability, it is easy for moisture to accumulate inside the cultivation facility using a thermoplastic resin film, especially from spring to summer, and food diseases are likely to occur when the cultivation facility is highly humid. Become. Since the humidity inside the cultivation facility has a great influence on the growth of crops, an agricultural film capable of adjusting the humidity inside the cultivation facility is required.

  Therefore, Patent Document 1 discloses an agricultural film having a plurality of through holes formed in a thermoplastic resin film by drilling using a needle. Further, in Patent Document 2, a moisture permeability adjusting film having a thickness of 1 to 15 μm is laminated on a cloth-like body formed by crossing linear bodies obtained by uniaxially stretching a thermoplastic resin, and the moisture permeability adjusting film is laminated. An agricultural film formed by laminating a porous sheet formed using a thermoplastic resin filament on top is disclosed. In these agricultural films, by providing air permeability, it is possible to adjust the humidity inside the cultivation facility by allowing air inside or outside the cultivation facility to pass therethrough.

Japanese Patent No. 4556353 JP 2004-160812 A

  However, in the conventional agricultural film, when the humidity outside the cultivation facility is high, the high humidity outside the cultivation facility enters the cultivation facility through the agricultural film, so the humidity inside the cultivation facility becomes high. There was a problem. For this reason, it has been difficult to keep the humidity inside the cultivation facility low in the conventional agricultural film provided with air permeability. Therefore, in order to keep the humidity inside the cultivation facility low, it is necessary to impart moisture absorption to the agricultural film, not to impart breathability to the agricultural film.

  Therefore, an object of this invention is to provide the agricultural film which has a hygroscopic property.

  The agricultural film of the present invention is characterized by including 100 parts by weight of a thermoplastic resin and 1 to 15 parts by weight of shochu cake.

  The agricultural film of the present invention is provided with excellent hygroscopicity by using shochu. Furthermore, according to the shochu cake, excellent hygroscopicity can be imparted to the agricultural film while highly suppressing a decrease in mechanical strength and transparency. Therefore, according to the film for agriculture of the present invention, it is possible to maintain the humidity inside the cultivation facility low according to the change in season and weather, and to provide a cultivation facility capable of stably growing crops. Can do.

  The agricultural film of the present invention contains a thermoplastic resin and a shochu cake.

(Thermoplastic resin)
Examples of the thermoplastic resin include an olefin resin, a vinyl chloride resin, an ester resin, a methyl methacrylate resin, and a carbonate resin. Of these, olefin resins are preferred. Examples of olefin resins include ethylene resins and propylene resins.

  The propylene-based resin is not particularly limited, and examples thereof include a propylene homopolymer, a copolymer of propylene and another olefin containing a propylene component in an amount exceeding 50% by weight, and are used alone. Or 2 or more types may be used together. Examples of the olefin copolymerized with propylene include α such as ethylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-octene, 1-nonene and 1-decene. -Olefin and the like. Further, the copolymer of propylene and another olefin may be a block copolymer or a random copolymer.

  Examples of the ethylene-based resin include an ethylene homopolymer or a copolymer of ethylene containing 50% by weight or more of an ethylene component and at least one α-olefin having 3 to 20 carbon atoms other than ethylene. Examples of the ethylene resin include high density polyethylene (HDPE), medium density polyethylene (MDPE), low density polyethylene (LDPE), and linear low density polyethylene (LLDPE). Linear low density polyethylene is a copolymer of ethylene and an α-olefin. In addition, 1-15 weight% is preferable and, as for content of the alpha olefin in a linear low density polyethylene, 1-10 weight% is more preferable.

  Examples of the α-olefin copolymerized with ethylene include propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-nonene, 1-decene, 1-decene, Examples include tetradecene, 1-hexadecene, 1-octadecene, and 1-eicocene. Especially, a C4-C10 alpha olefin is preferable and 1-octene is more preferable.

  As the olefin resin, an ethylene resin is preferable, and a linear low density polyethylene is more preferable. By using the ethylene-based resin, it is possible to reduce the decrease in mechanical strength of the agricultural film due to the addition of shochu cake.

The density of the ethylene-based resin is preferably 0.90~0.98g / cm ^3, more preferably 0.91~0.94g / cm ^3, particularly preferably from 0.915 to 0.925. If the density of the ethylene-based resin is too low, the mechanical strength of the agricultural film may be insufficient, or the agricultural film may be easily blocked, and it may be difficult to stretch the agricultural film. Moreover, when the density of ethylene-type resin is too high, an agricultural film will become hard too much and there exists a possibility that the handleability of an agricultural film may fall.

  The density of the ethylene-based resin in the present invention means a value measured in accordance with JIS K7112 “Plastics—Method for measuring density and specific gravity of non-foamed plastic”.

  The melt flow rate (MFR) of the thermoplastic resin is preferably 0.2 to 10 g / 10 minutes, and more preferably 0.4 to 3 g / 10 minutes. If the MFR of the thermoplastic resin is too small, the film formability of the agricultural film may be reduced. Moreover, when MFR of a thermoplastic resin is too large, there exists a possibility that the mechanical strength of an agricultural film may fall.

  Here, the MFR of the thermoplastic resin in the present invention is in accordance with JIS K7210 “Plastics—Testing Method for Melt Mass Flow Rate and Melt Volume Flow Rate of Thermoplastic Plastic” under conditions of a temperature of 190 ° C. and a load of 21.18 N. Refers to the measured value.

(Shomei-don)
The agricultural film of the present invention contains shochu cake. A shochu cake is made of an anhydride obtained by firing alum. Alum contains crystal water, and such alum gradually discharges crystal water when fired to become an anhydrate, that is, “sake alum”. By using such a shochu cake, an agricultural film having excellent hygroscopicity can be provided. Furthermore, the agricultural film that has absorbed moisture by shochu lees can be humidified by releasing the absorbed moisture when the ambient humidity is low, and has excellent humidification properties. Therefore, the agricultural film containing shochu cake has excellent hygroscopicity and moisturizing properties, and thereby the humidity inside the cultivation facility can be adjusted.

  Moreover, the agricultural film of this invention can adjust the humidity inside a cultivation facility, without providing air permeability by a through-hole etc. Therefore, the agricultural film does not need to have a through-hole, which prevents high humidity outside the cultivation facility from entering the cultivation facility through the agricultural film, thereby increasing the humidity inside the cultivation facility. can do.

  Furthermore, according to shochu, it is possible to impart excellent hygroscopicity and humidification to the agricultural film without reducing the transparency and mechanical strength of the agricultural film. Therefore, the agricultural film of the present invention can transmit light from the outside such as sunlight with high transmittance in spite of having excellent hygroscopicity and humidification, as well as wind and rain, It is also possible to prevent the crops in the cultivation facility from being damaged by flying objects such as dust and dirt.

  Shochu is made of an anhydride obtained by baking alum. As an alum, preferred is a double salt represented by the following general formula (1) or the following general formula (2).

M ¹ M ² (SO ₄ ) ₂ · 12H ₂ O (1)
(In the general formula (1), M ¹ is a monovalent cation and represents Na ⁺ , K ⁺ , Rb ⁺ , Cs ⁺ , or NH ₄ ⁺ , and M ² is a trivalent metal ion. And Al ³⁺ , Ga ³⁺ , In ³⁺ , Ti ³⁺ , V ³⁺ , Cr ³⁺ , Mn ³⁺ , Fe ³⁺ , Co ³⁺ , Rh ³⁺ , or Ir ³⁺ . )

M ³ ₂ (SO ₄ ) ₃ · M ⁴ ₂ SO ₄ · 24H ₂ O (2)
(In the general formula (2), M ³ is a trivalent metal ion, and Al ³⁺ , Ga ³⁺ , In ³⁺ , Ti ³⁺ , V ³⁺ , Cr ³⁺ , Mn ³⁺ , Fe ³⁺ , Co ³⁺ , Rh ³⁺ , or Ir ³⁺ , where M ⁴ is a monovalent cation and is Na ⁺ , K ⁺ , Rb ⁺ , Cs ⁺ , NH ₄ ⁺ , or Tl ⁺ Is shown.)

Specifically, potassium alum [KAl (SO ₄ ) ₂ · 12H ₂ O], iron alum [KFe (SO ₄ ) ₂ · 12H ₂ O], ammonium aluminum alum [NH ₄ Al (SO ₄ ) ₂ 12H ₂ O], ammonium gallium alum [NH ₄ Ga (SO ₄ ) ₂ .12H ₂ O], ammonium chrome alum [NH ₄ Cr (SO ₄ ) ₂ · 12H ₂ O], ammonium cobalt alum [NH ₄ Co ( SO ₄ ) ₂ · 12H ₂ O] and ammonium iron alum [NH ₄ Fe (SO ₄ ) ₂ · 12H ₂ O].

  As the shochu cake, an anhydride obtained by firing potash cake is preferable. According to such a shochu cake, excellent hygroscopicity and humidification properties can be imparted to agricultural films while highly suppressing the decrease in transparency and mechanical strength. In addition, shochu cake may be used individually by 1 type, and 2 or more types may be used together. Moreover, shochu can be manufactured by baking alum and removing crystal water according to a well-known method.

  The content of the shochu cake in the agricultural film is limited to 1 to 15 parts by weight with respect to 100 parts by weight of the thermoplastic resin, preferably 5 to 15 parts by weight, and more preferably 5 to 10 parts by weight. If the content of the shochu cake is too high, bubbles may be generated in the agricultural film due to a large amount of moisture absorbed by the shochu cake. Moreover, when the content of shochu is too low, there is a possibility that sufficient hygroscopicity and humidification cannot be imparted to the agricultural film.

(Other additives)
The agricultural film of the present invention, in addition to the above-mentioned shochu cake, other additives such as hindered amine light stabilizers, antioxidants, heat stabilizers, ultraviolet absorbers, lubricants, and anti-blocking agents as necessary An agent may be included. Another additive may be used independently or 2 or more types may be used together.

  Examples of the hindered amine light stabilizer 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 and 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. The hindered amine light stabilizers may be used alone or in combination of two or more.

  Examples of the antioxidant include metal salts of carboxylic acids, phenolic antioxidants, chelators such as organic phosphites, and the like. An antioxidant may be used independently or 2 or more types may be used together.

  Examples of the heat stabilizer include chelators such as metal salts of carboxylic acids, phenolic antioxidants, and organic phosphites. A heat stabilizer may be used independently or 2 or more types may be used together.

  Examples of the UV absorber include benzophenone UV absorbers, benzotriazole UV absorbers, salicylic acid ester UV absorbers, and cyanoacrylate UV absorbers. Specifically, as a benzophenone-based ultraviolet absorber, 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, etc .; 2- (2′-hydroxy-5′-) as a benzotriazole ultraviolet absorber tert-butylphenyl) benzotriazole, 2- (2′-hydroxy-5′-methylphenyl) benzotriazole, 2- (2′-hydroxy-3′-tert-butyl-5-methylphenyl) -5 Chlorobenzotriazole, 2- (2′-hydroxy-3 ′, 5′- Such -tert- butylphenyl) -5-chloro benzotriazole. An ultraviolet absorber may be used independently or 2 or more types may be used together.

  Examples of the lubricant 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. The lubricants may be used alone or in combination of two or more.

  25-200 micrometers is preferable and, as for the thickness of the agricultural film of this invention, 50-100 micrometers is more preferable. If the agricultural film is too thin, the mechanical strength of the agricultural film may be reduced. On the other hand, if the agricultural film is too thick, the agricultural film becomes too hard, and the handleability of the agricultural film may be reduced.

  The agricultural film of the present invention can be produced according to a known method such as a melt extrusion method or a calendar method. Of these, the melt extrusion method is preferable.

  In order to produce an agricultural film by the melt extrusion method, for example, a thermoplastic resin and a shochu cake are supplied to an extruder, melt kneaded, and then extruded from the extruder. The extrusion method is not particularly limited, and examples thereof include a T-die method and an inflation method.

  Agricultural film production using the T-die method involves preparing an extruder with a T-die attached, supplying thermoplastic resin, shochu cake, etc. to the extruder, melt-kneading, and then using the T-die attached to the extruder. An agricultural film can be produced by extrusion. In addition, the production of agricultural films using the inflation method is performed by, for example, melting and kneading a thermoplastic resin and shochu cake in an extruder to obtain a molten resin composition, and then the molten resin from the extruder. The composition is supplied to a circular die, the molten resin composition is extruded from the circular die to form a cylindrical film, and compressed air is supplied from the center of the circular die to form an extrusion film. An agricultural film can be produced by stretching the formed cylindrical film in the circumferential direction.

  As an application of an agricultural film, a covering material in an agricultural house such as a greenhouse or an agricultural facility such as an agricultural tunnel is preferably exemplified. For example, an agricultural film is used by spreading and fixing the film so as to cover the outside of a housing made of a metal pipe or the like in a cultivation facility.

  As described above, the agricultural film of the present invention is imparted with excellent hygroscopicity and humidification while highly suppressing a decrease in mechanical strength and transparency. In an agricultural facility using such an agricultural film, the internal humidity can be easily adjusted by the agricultural film, and the crop can be protected from poor growth due to high humidity or drying. Therefore, such an agricultural facility can be used, for example, for cultivating horticultural plants such as flower buds, spinach, Japanese mustard spinach, chingen vegetables, celery, vegetables such as mizuna and radishes, breeding livestock, or storing fertilizers. .

  Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited thereto.

(Examples 1-3 and Comparative Examples 1-5)
Linear low density polyethylene (LLDPE, density 0.923 g / cm ³ , MFR 1.5 g / 10 min, product name “SP2510” manufactured by Prime Polymer Co., Ltd.) Kogyo Co., Ltd., trade name “Pericon PE2125”), quicklime (composition: CaO, manufactured by Dainichi Seika Kogyo Co., Ltd., trade name “Pericon PE2407”), hydrotalcite (trade name “DHT-4A” manufactured by Kyowa Chemical Co., Ltd.), Zeolite (trade name “SP2300” manufactured by Nippon Clean Pack Co., Ltd.) and hindered amine light stabilizer (HALS: product name “TINUVIN 783 FDL” manufactured by BASF Japan Co., Ltd.) were used in the amounts shown in Table 1, respectively. The molten resin composition was obtained by supplying to an extruder and melt-kneading.

  Next, the molten resin composition was supplied from an extruder to a circular die, and the molten resin composition was extruded from the circular die to obtain a cylindrical film. Thereafter, compressed air was supplied from the center of the circular die, the extruded cylindrical film was stretched in the circumferential direction, and then the cylindrical film was cooled with cooling air. And the film for agriculture (100 micrometers in thickness) was obtained by cutting and winding up the cooled cylindrical film.

(Evaluation)
The agricultural film was evaluated for hygroscopicity, humidification, mechanical strength, and transparency according to the following procedures. The results are shown in Table 1.

(Hygroscopic)
By cutting the agricultural film, a flat rectangular test piece of 5 cm × 10 cm was obtained. This test piece was left in an environment of a temperature of 40 ° C. and a relative humidity of 90% for 100 hours. Then, by measuring the weight (W _a ) of the test piece before being left and the weight (W _b ) of the test piece after being left, and calculating the weight increase rate [%] based on the following formula (1), Hygroscopicity was evaluated.
Weight increase rate [%] = 100 × (W _b −W _a ) / W _a (1)

(Humidification)
By cutting the hygroscopic film, a flat rectangular test piece of 5 cm × 10 cm was obtained. The test piece was left in an environment of a temperature of 40 ° C. and a relative humidity of 90% for 100 hours, and then left in an environment of a temperature of 60 ° C. and a relative humidity of 20% for 100 hours. The weight of the test piece before being left (w ₀ ), the temperature of 40 ° C., the weight of the test piece after being left in an environment of 90% relative humidity (w ₁ ), and the environment of 60 ° C. and 20% relative humidity. Humidity was evaluated by measuring the weight (W ₂ ) of the test piece after leaving it underneath and calculating the weight reduction rate based on the following formula (2).
Weight reduction rate [%] = 100 × [(W ₁ −W ₀ ) − (W ₂ −W ₀ )] / (W ₁ −W ₀ ) (2)

(Mechanical strength)
The tensile breaking strength [g] of the agricultural film was measured using a universal tensile testing machine (device name “STROGRAP E-L” manufactured by Toyo Seiki Seisakusho Co., Ltd.) according to JIS K7128.

(transparency)
The total light transmittance [%] in the thickness direction of the agricultural film was measured using a haze meter (Nippon Denshoku Co., Ltd., device name “NDH2000”).

Claims (4)

  An agricultural film comprising 100 parts by weight of a thermoplastic resin and 1 to 15 parts by weight of shochu cake.   The agricultural film according to claim 1, wherein the thermoplastic resin contains an ethylene-based resin.   The agricultural film according to claim 1 or 2, wherein the thermoplastic resin contains linear low-density polyethylene.   The agricultural film according to any one of claims 1 to 3, wherein the shochu cake contains an anhydride obtained by firing potash koji.