Agricultural film

Abstract

To provide an agricultural film which has improved environment consideration property while having optical characteristics and mechanical physical property equivalent to an agricultural film produced using only a resin obtained from a fossil fuel.SOLUTION: An agricultural film includes a mixture layer containing an ethylene-vinyl acetate copolymer (A) and polyolefin (B), wherein a biomass degree measured according to ASTM D 6866 of the mixture layer exceeds 0 mass% and is 100 mass% or less.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present disclosure relates to agricultural films. [Background technology]

[0002] Generally, agricultural films with a high light transmittance are desirable, but for some types of crops, it is desirable to minimize the proportion of direct light and increase the proportion of scattered light. For example, in seedling greenhouses for soft vegetables such as tobacco leaves and lettuce, it is essential to use agricultural films with little direct light to prevent the leaves from sunburn. Also, in drying greenhouses for tobacco leaves, it is essential to use agricultural films with little direct light to prevent rapid drying or the occurrence of rotten or damaged leaves. For this reason, satin-like agricultural films have been used.

[0003] As an example of a matte-textured agricultural film, Patent Document 1 discloses an agricultural film in which at least one of the outermost and innermost layers is a mixture layer consisting of an ethylene-vinyl acetate copolymer (A) having a vinyl acetate content of 24 to 34% by weight and a melt flow rate (MFR) of 4 to 50 g / 10 min and a low-density polyethylene (B) having an MFR of 0.04 to 2.0 g / 10 min, the mixture ratio of (A) and (B) being (A) / (B)=35 to 90 / 65 to 10 (weight ratio), the average vinyl acetate content of the mixture being 12 to 22% by weight, and the MFR ratio (MFR of (A) / MFR of (B))=10 to 100, and which has a multilayer structure consisting of the mixture layer and another olefin-based resin layer, and which has a total light transmittance of 80% or more and a trans of 10% or less. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 3219319 Summary of the Invention [Problem to be solved by the invention]

[0005] On the other hand, resins such as ethylene-vinyl acetate copolymer (A) and low-density polyethylene (B) used in such agricultural films are derived from fossil fuels. However, for example, petroleum, which is a fossil fuel, is in danger of being depleted, and since it emits a large amount of carbon dioxide during the manufacturing process and disposal process after the product is made, there are concerns about its impact on global warming. It is also required that agricultural films be manufactured while taking the environment into consideration. Furthermore, even when agricultural films are manufactured while taking the environment into consideration, they are required to have optical properties and mechanical properties equivalent to those of agricultural films manufactured using only resins obtained from fossil fuels such as petroleum.

[0006] The problem that one embodiment of the present disclosure aims to solve is to provide an agricultural film that has improved environmental friendliness while having optical properties and mechanical properties equivalent to those of agricultural films produced using only resins derived from fossil fuels. [Means for solving the problem]

[0007] Means for solving the above problems include the following aspects. <1> Ethylene-vinyl acetate copolymer (A) and A polyolefin (B); A mixture layer containing The agricultural film, wherein the biomass content of the mixture layer, as measured in accordance with ASTM D6866, is greater than 0 mass % and is 100 mass % or less. <2> In the ethylene-vinyl acetate copolymer (A), the content of structural units derived from vinyl acetate is 12% by mass or more and 35% by mass or less. <1> 2. The agricultural film according to claim 1 . <3> The ethylene-vinyl acetate copolymer (A) has a melt flow rate (MFR, JIS K 7210-1999, 190°C, 2160g load) of 4g / 10 minutes or more and 100g / 10 minutes or less. <1> or <2> 2. The agricultural film according to claim 1 . <4> The polyolefin (B) includes at least one selected from the group consisting of high density polyethylene and metallocene-catalyzed polyethylene. <1> ~ <3> 13. The agricultural film according to claim 12, <5> The polyolefin (B) further includes low density polyethylene; <4> 2. The agricultural film according to claim 1 . <6> a content ratio of the ethylene-vinyl acetate copolymer (A) and the polyolefin (B) in the mixture layer [(A):(B)] is 35:65 to 85:15 in terms of mass ratio; <1> ~ <5> 13. The agricultural film according to claim 12, <7> When the resin component in the mixture layer is taken as 100% by mass, the average content of the structural units derived from vinyl acetate is 1% by mass or more and less than 30% by mass. <1> ~ <6> 13. The agricultural film according to claim 12, <8> The mixture layer is the outermost layer. <1> ~ <7> 13. The agricultural film according to claim 12, <9> The MFR of the ethylene-vinyl acetate copolymer (A) A and the MFR of the polyolefin (B) B Ratio of (MFR A / MFR B ) is between 10 and 100, <1> ~ <8> 13. The agricultural film according to claim 12, <10> The ethylene-vinyl acetate copolymer (A) contains a biomass ethylene-vinyl acetate copolymer obtained by polymerizing a monomer containing ethylene derived from biomass. <1> ~ <9> 13. The agricultural film according to claim 12, <11> The polyolefin (B) contains a biomass polyolefin obtained by polymerizing a monomer containing ethylene derived from biomass. <1> ~ <10> 13. The agricultural film according to claim 12, <12> a total content of the ethylene-vinyl acetate copolymer (A) and the polyolefin (B) is 2% by mass or more and 100% by mass or less, when the entire mixture layer is taken as 100% by mass; <1> ~ <11> 13. The agricultural film according to claim 12, Effect of the Invention

[0008] According to one embodiment of the present disclosure, an agricultural film is provided that has optical properties and mechanical properties equivalent to those of agricultural films produced using only resins derived from fossil fuels, while being more environmentally friendly. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment that is an example of the agricultural film of the present disclosure will be described. The present disclosure is not limited to the following embodiment, and can be modified as appropriate within the scope of the object of the present disclosure.

[0010] In this disclosure, "to" in a numerical range means that the numerical values ​​before and after "to" are included. In the numerical ranges described in stages in this disclosure, the upper limit or lower limit described in a certain numerical range may be replaced with the upper limit or lower limit of another numerical range described in stages. In addition, in the numerical ranges described in this disclosure, the upper limit or lower limit described in a certain numerical range may be replaced with a value shown in the examples. In the present disclosure, when a plurality of substances corresponding to each component are present in the composition, the amount of each component in the composition means the constituent units of the plurality of substances present in the composition, unless otherwise specified.

[0011] In the present disclosure, the term "pear-skinned" refers to a surface state having a rough texture with a plurality of irregular, minute, spot-like irregularities like the skin of a pear. The total light transmittance value is preferably 85% or more and less than 95%, and the haze value is preferably 70% or more and less than 95%.

[0012] [Agricultural film] The agricultural film of the present disclosure includes a mixture layer containing an ethylene-vinyl acetate copolymer (A) and a polyolefin (B), and the mixture layer has a biomass content of more than 0 mass% and not more than 100 mass%, as measured in accordance with ASTM D6866. The agricultural film of the present disclosure has improved environmental friendliness while maintaining optical properties (e.g., total light transmittance, haze) and mechanical properties (e.g., stress at break, elongation at break) equivalent to those of agricultural films produced using only resins derived from fossil fuels.

[0013] Each component contained in the agricultural film of the present disclosure will be described in detail below. Unless otherwise specified, the melt flow rate (MFR) in this disclosure is a value [g / 10 min] measured at 190° C. under a load of 2160 g in accordance with Japanese Industrial Standard JIS K7210-1999.

[0014] [Mixture layer] The agricultural film of the present disclosure has a mixture layer containing an ethylene-vinyl acetate copolymer (A) and a polyolefin (B). The mixture layer may contain other polymers, additives, etc., as necessary.

[0015] <Ethylene-vinyl acetate copolymer (A)> The ethylene-vinyl acetate copolymer (A) used in the present disclosure contains at least a structural unit derived from ethylene and a structural unit derived from vinyl acetate. The ethylene-vinyl acetate copolymer (A) may be a random copolymer, a block copolymer, or an alternating copolymer. The ethylene-vinyl acetate copolymer (A) may further contain a constituent unit derived from a monomer other than vinyl acetate and ethylene. In the present disclosure, it is preferable that the ethylene-vinyl acetate copolymer does not contain any monomer unit other than vinyl acetate and ethylene, and is composed of a constituent unit derived from vinyl acetate and a constituent unit derived from ethylene.

[0016] The ethylene-vinyl acetate copolymer (A) in the present disclosure contains structural units derived from ethylene and structural units derived from vinyl acetate, and may optionally further contain structural units derived from other monomers.

[0017] The ethylene-vinyl acetate copolymer (A) preferably contains a structural unit derived from biomass, and more preferably contains a biomass ethylene-vinyl acetate copolymer obtained by polymerizing a monomer containing ethylene derived from biomass. In addition, when the ethylene-vinyl acetate copolymer (A) contains a structural unit derived from an α-olefin other than ethylene, the α-olefin other than ethylene may be derived from biomass. The ethylene-vinyl acetate copolymer (A) may contain a biomass ethylene-vinyl acetate copolymer obtained by polymerizing a monomer containing an α-olefin derived from biomass (α-olefin other than ethylene).

[0018] From the viewpoint of further improving environmental friendliness, the biomass degree of the ethylene-vinyl acetate copolymer (A) is preferably more than 0% by mass, more preferably 0.01% by mass or more, even more preferably 0.1% by mass or more, even more preferably 10% by mass or more, even more preferably 20% by mass or more, even more preferably 30% by mass or more, even more preferably 40% by mass or more, even more preferably 50% by mass or more, even more preferably 60% by mass or more, even more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more. There is no particular upper limit to the biomass degree of the ethylene-vinyl acetate copolymer (A), and it is preferably 100% by mass or less. It is preferable that at least one of the biomass degree of the ethylene-vinyl acetate copolymer (A) and the biomass degree of the polyolefin (B) described below exceeds 0 mass%, and only one of the biomass degree of the ethylene-vinyl acetate copolymer (A) and the biomass degree of the polyolefin (B) described below (for example, the biomass degree of the ethylene-vinyl acetate copolymer (A)) may be 0 mass%.

[0019] Regarding the biomass-derived ethylene used in the production of the ethylene-vinyl acetate copolymer (A), the production method of ethylene and the biomass ratio are described later.

[0020] The ethylene-vinyl acetate copolymer (A) in the present disclosure preferably has a content of structural units derived from vinyl acetate of 12% by mass or more and 35% by mass or less. When the content of structural units derived from vinyl acetate is 12% by mass or more and 35% by mass or less, the haze of the resulting film is likely to be favorable for agricultural films. From the viewpoint of haze value, the content of structural units derived from vinyl acetate is more preferably from 16% by mass to 30% by mass, and further preferably from 18% by mass to 25% by mass.

[0021] The content of structural units derived from ethylene is preferably 65% ​​by mass or more and 88% by mass or less, more preferably 70% by mass or more and 84% by mass or less, and even more preferably 75% by mass or more and 82% by mass or less. The content of structural units derived from other monomers may be 10% by mass or less, and is preferably 0% by mass.

[0022] The melt flow rate (MFR, JIS K 7210-1999, 190°C, 2160 g load) of the ethylene-vinyl acetate copolymer (A) in the present disclosure is preferably 4 g / 10 min or more and 100 g / 10 min or less, more preferably 8 g / 10 min or more and 60 g / 10 min or less, even more preferably 10 g / 10 min or more and 50 g / 10 min or less, and particularly preferably 12 g / 10 min or more and 30 g / 10 min or less. When the MFR of the ethylene-vinyl acetate copolymer (A) is 4 g / 10 min or more and 100 g / 10 min or less, the haze value of the resulting film is favorable for agricultural films.

[0023] The ethylene-vinyl acetate copolymer (A) may be used alone or in combination of two or more different copolymerization ratios. In order to obtain an agricultural film with excellent mechanical strength, the content of the ethylene-vinyl acetate copolymer (A) in the mixture layer of the present disclosure is preferably from 35% by mass to 85% by mass, more preferably from 40% by mass to 60% by mass, and even more preferably from 40% by mass to 50% by mass, based on the total mass of the mixture layer.

[0024] <Polyolefin (B)> The polyolefin (B) used in the present disclosure is not particularly limited as long as it is a polymer containing structural units derived from an olefin.

[0025] The polyolefin (B) preferably contains at least one selected from the group consisting of high density polyethylene and metallocene-catalyzed polyethylene. When the polyolefin (B) contains one of the above types, the agricultural film of the present disclosure tends to have excellent mechanical properties. The polyolefin (B) preferably contains high density polyethylene from the viewpoint of obtaining excellent mechanical properties, particularly groove tear strength and breaking elongation.

[0026] Here, high density polyethylene is defined as polyethylene having a density of 935 kg / m according to the old JIS K6748:1995. 3 The above polyethylenes are usually produced by low pressure or medium pressure processes. The low pressure process includes the Ziegler process, and the medium pressure process includes the Phillips process. Metallocene-catalyzed polyethylene is produced using a homogeneous catalyst such as a metallocene catalyst, and examples of such polyethylene include linear low-density polyethylene (LLDPE) produced using a metallocene catalyst. The polyethylene may also be an ethylene-α-olefin copolymer obtained by copolymerizing ethylene with an α-olefin.

[0027] The polyolefin (B) may contain other polyolefins than those mentioned above. Other polyolefins include low-density polyethylenes such as high-pressure low-density polyethylene, ethylene-unsaturated carboxylic acid copolymers, ethylene-vinyl acetate copolymers, ethylene-α-olefin copolymer elastomers that have reduced crystallinity or exhibit essentially no crystallinity by increasing the amount of α-olefins other than ethylene copolymerized with ethylene (propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene, 4-methyl-1-pentene, etc.), polypropylene, propylene copolymers (copolymers of propylene and α-olefins other than propylene), polybutene, other olefin (co)polymers, and polymer blends thereof.

[0028] The polyolefin (B) preferably contains a structural unit derived from biomass, and preferably contains a biomass polyolefin obtained by polymerizing a monomer containing ethylene derived from biomass.

[0029] In addition, when the polyolefin (B) contains a structural unit derived from an α-olefin other than ethylene, the α-olefin other than ethylene may be derived from biomass. The polyolefin (B) may contain a polyolefin (B) obtained by polymerizing a monomer containing an α-olefin (α-olefin other than ethylene) derived from biomass.

[0030] From the viewpoint of further improving environmental friendliness, the biomass degree of polyolefin (B) is preferably more than 0% by mass, more preferably 0.01% by mass or more, even more preferably 0.1% by mass or more, even more preferably 10% by mass or more, even more preferably 20% by mass or more, even more preferably 30% by mass or more, even more preferably 40% by mass or more, even more preferably 50% by mass or more, even more preferably 60% by mass or more, even more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more. There is no particular upper limit to the biomass degree of polyolefin (B), and it is preferably 100% by mass or less.

[0031] Regarding the biomass-derived ethylene used in the production of the polyolefin (B), the production method of ethylene and the biomass content are as described below.

[0032] In order to obtain excellent mechanical strength, the content of polyolefin (B) in the mixture layer of the agricultural film of the present disclosure is preferably from 15% by mass to 65% by mass, more preferably from 40% by mass to 60% by mass, and even more preferably from 50% by mass to 60% by mass, based on the entire mixture layer.

[0033] Here, the polyolefin (B) contained in the mixture layer may further contain low-density polyethylene in addition to at least one selected from the group consisting of high-density polyethylene and metallocene-catalyzed polyethylene. The low-density polyethylene is defined as a polyethylene having a density of 930 kg / m according to the old JIS K6748:1995. 3 It is a polyethylene having a molecular weight of less than 1000 and is produced by a high-pressure method (bulk polymerization method). In addition, the low-density polyethylene in this disclosure does not include linear low-density polyethylene (LLDPE). In this case, from the viewpoint of obtaining excellent mechanical properties, the content of the low-density polyethylene is preferably less than 30 mass%, more preferably less than 20 mass%, even more preferably less than 15 mass%, and particularly preferably 0 mass%, relative to the entire mixture layer.

[0034] In the present disclosure, the MFR of the polyolefin (B) is preferably 5 g / 10 min or less, more preferably 3 g / 10 min or less, and even more preferably 1.5 g / 10 min or less, from the viewpoint of obtaining a matte film. The lower limit of the MFR of the polyolefin (B) is preferably 0.04 g / 10 min or more. MFR of ethylene-vinyl acetate copolymer (A) A and MFR of polyolefin (B) B Ratio to (MFR A / MFR B) is preferably 10 or more and 100 or less, more preferably 10 or more and 80 or less, and even more preferably 10 or more and 60 or less.

[0035] In the mixture layer of the agricultural film of the present disclosure, the content ratio of the ethylene-vinyl acetate copolymer (A) and the polyolefin (B) [(A):(B)] is preferably 35:65 to 85:15 by mass. When the mass ratio of the ethylene-vinyl acetate copolymer (A) is within the above range, the resulting film tends to have a preferable haze value and grave tear strength. Therefore, by having the mass ratio of the ethylene-vinyl acetate copolymer (A) and the polyolefin (B) within the above range, it becomes easier to obtain an agricultural film having excellent mechanical strength while maintaining the haze value within an acceptable range. Within the above range, the content ratio of the ethylene-vinyl acetate copolymer (A) and the polyolefin (B) [(A):(B)] is preferably from 40:60 to 80:20, more preferably from 40:60 to 70:30, even more preferably from 40:60 to 60:40, and particularly preferably from 40:60 to 50:50, from the viewpoint of obtaining a film having excellent mechanical strength while maintaining the haze value within an acceptable range.

[0036] <Biomass-derived ethylene> The method for producing ethylene derived from biomass according to the present disclosure is not limited, and a known method can be used. Examples of the method for producing ethylene derived from biomass are given below.

[0037] "Biomass" refers to organic resources that are primarily derived from plants and animals, excluding fossil fuels. Methods for producing biomass-derived ethylene include, for example, a method in which plant raw materials (the former raw materials described below) are fermented by microorganisms to produce biomass-derived ethanol (bioethanol) and then dehydrated, and a method in which ethylene is extracted from biomass naphtha produced using vegetable oil waste, residual oil, etc. as raw materials (the latter raw materials described below). The former raw materials include non-edible raw materials and edible raw materials. Examples of non-edible raw materials include cellulosic crops such as pulp, kenaf, and rice straw, waste paper, papermaking residues, wood, charcoal, compost, natural rubber, cotton, factory flue gas, waste gas, etc. Examples of edible raw materials include carbohydrate crops such as sugarcane, soybean pulp, corn, potatoes, wheat, and rice, buckwheat, and soybeans. As the former raw materials, one or more types selected from the group consisting of these can be used. Examples of the latter raw material include various waste materials, unused resources, resource crops, etc. Specific examples include oils and fats such as rapeseed oil and soybean oil, essential oils such as eucalyptus oil, vegetable oil cakes, etc. From the viewpoint of reducing the amount of carbon dioxide generated in the life cycle from the raw material to the disposal of the plastic product, it is preferable to use ethylene extracted from biomass naphtha.

[0038] Ethylene can be extracted from biomass naphtha by known methods such as heating, cracking, distillation, and purification, in the same manner as extraction from naphtha derived from fossil fuels.

[0039] The method for producing bioethanol is not particularly limited, and for example, ethanol can be produced by contacting edible biomass raw materials such as sugarcane and corn with ethanol-producing microorganisms, such as yeast, or products derived from their crushed material to ferment sugar, and then purifying the ethanol. Ethanol can be purified by conventional methods such as distillation, membrane separation, and extraction. In addition, as a method for producing bioethanol using non-edible raw materials as biomass raw materials, for example, synthetic gas (gas mainly composed of carbon monoxide, hydrogen, etc.) generated by burning non-edible raw materials that are waste resources such as waste paper and papermaking residues, flue gas emitted from factories, waste gas, etc. can be used as a carbon source to obtain ethanol by fermenting them with microorganisms.

[0040] The ethanol obtained as described above can be dehydrated to obtain ethylene derived from biomass. The dehydration reaction requires certain conditions such as the type of catalyst, heating temperature, and pressure, but any of the conventional methods can be used.

[0041] In the process of producing ethylene derived from biomass obtained in this manner, by-products such as higher alcohols and higher alkene impurities may be generated during the ethanol fermentation process, dehydration process, etc. For this reason, such by-products can be removed before or after the dehydration of ethanol.

[0042] Furthermore, biomass-derived α-olefins (α-olefins other than ethylene) can also be produced using the above-mentioned biomass-derived ethylene as a raw material in the same manner as in the case of using fossil fuel-derived ethylene as a raw material.

[0043] <Biomass ratio> In the mixture layer of the agricultural film of the present disclosure, the biomass degree of the entire mixture layer of the agricultural film, measured in accordance with ASTM D6866, is more than 0% by mass, preferably 1% by mass or more, more preferably 3% by mass or more, and even more preferably 5% by mass or more, from the viewpoint of improving environmental friendliness. There is no upper limit for the biomass degree of the entire mixture layer of the agricultural film, and it may be 100% by mass or less, 90% by mass or less, 80% by mass or less, 70% by mass or less, or 60% by mass or less. In ASTM D6866, radiocarbon from biomass ( 14 The biomass ratio is calculated by measuring the carbon concentration of fossil fuels. 14 C) shows a constant value, making it possible to distinguish it from biomass-derived carbon. For example, when polyethylene has a biomass content of more than 0 mass% but less than 100 mass%, it can be said to contain both biomass-derived ethylene and fossil fuel-derived ethylene.

[0044] In the present disclosure, the polymerization method for the ethylene-vinyl acetate copolymer (A) containing biomass-derived ethylene and the polyolefin (B) containing biomass-derived ethylene is not limited, and a conventionally known method similar to that in the case where fossil fuel-derived ethylene is used as a raw material can be used. In addition, when the ethylene-vinyl acetate copolymer (A) and the polyolefin (B) contain a biomass-derived α-olefin (an α-olefin other than ethylene), a polymerization method similar to that used when a fossil fuel-derived α-olefin (an α-olefin other than ethylene) is used as a raw material can be used.

[0045] <Other polymers> The mixture layer may or may not contain other polymers. Examples of other polymers include ethylene-(meth)acrylic acid copolymers and ionomers. The content of other polymers may be 30% by mass or less, 10% by mass or less, or 0% by mass based on the total amount of the agricultural film.

[0046] <Other additives> The mixture layer may or may not contain other additives. As other additives, conventionally known chemical crosslinking agents, crosslinking assistants, softeners, fillers, antioxidants, heat stabilizers, weather stabilizers, acetic acid supplements, heat retaining agents, ultraviolet absorbers, anti-fogging agents, anti-fog agents, etc. may be appropriately blended. As the heat retaining agent, a known agent having a refractive index close to that of the mixture layer can be used. As the heat retaining agent, it is most preferable to use hydrotalcite, which has particularly good heat retaining properties and does not adversely affect light transmittance. The content of other additives is preferably 30% by mass or less based on the entire agricultural film.

[0047] <Mixture layer> The mixture layer of the agricultural film of the present disclosure preferably has an average content of structural units derived from vinyl acetate of 1% by mass or more and less than 30% by mass, more preferably 3% by mass or more and 25% by mass or less, even more preferably 5% by mass or more and 15% by mass or less, and even more preferably 7% by mass or more and 10% by mass or less, when the resin component in the mixture layer is taken as 100% by mass. When the average content of the constituent units derived from vinyl acetate in the resin component of the mixture layer is within the above range, adhesion can be suppressed and the matte finish can be maintained.

[0048] The "average content of constituent units derived from vinyl acetate" can be determined in accordance with JIS-K7192:1999. This method involves heating the polymer to 500°C or higher in an electric furnace to decompose it, and determining the acetic acid derived from the resulting vinyl acetate by neutralization titration. This method can be used to determine the average content of constituent units derived from vinyl acetate whether it is an ethylene-vinyl acetate copolymer alone or a mixture with various polyethylenes.

[0049] From the viewpoint of film processability, the MFR of the mixture layer is preferably 0.1 g / 10 min to 30 g / 10 min, more preferably 0.3 g / 10 min to 15 g / 10 min. By having the MFR of the mixture layer within the above range, the film processability is excellent.

[0050] The total content of the ethylene-vinyl acetate copolymer (A) and the polyolefin (B) is preferably from 2 to 100 mass%, more preferably from 70 to 100 mass%, even more preferably from 80 to 100 mass%, and particularly preferably from 90 to 100 mass%, when the entire mixture layer is taken as 100 mass%.

[0051] The thickness of the mixture layer is preferably from 3 μm to 500 μm, and more preferably from 10 μm to 200 μm.

[0052] [Layers other than the mixture layer] The agricultural film of the present disclosure may have layers other than the above-mentioned mixture layer from the viewpoint of obtaining necessary properties such as mechanical strength, durability, and heat retention suited to agricultural films. Specific examples of layers other than the mixture layer include an olefin resin layer, a barrier resin layer using a barrier resin such as EVOH (ethylene-vinyl alcohol copolymer resin), and the like.

[0053] The mixture layer in the present disclosure is preferably the outermost layer from the viewpoint of suppressing excessive direct light reaching the plant.

[0054] [Method of manufacturing agricultural film] Examples of a method for producing the agricultural film according to the present disclosure include a method in which a mixture containing the above-mentioned components is prepared and then molded into a film by a known method. Hereinafter, a method for producing an agricultural film having a single mixture layer will be described. However, the method for producing an agricultural film in the present disclosure is not limited to the following method.

[0055] For example, the mixture is prepared by dry blending or melt blending the above components. In the case of dry blending, the components are mixed at the stage of melt plasticization in a molding machine. In the case of melt blending, the components may be melt mixed using various extruders such as single-screw or twin-screw extruders, various mixers such as Banbury mixers, rolls, kneaders, or other compounding or mixing machines. There is no particular restriction on the order of mixing in the case of melt blending. Thereafter, the mixture is molded into a film by a known method such as an inflation method or a casting method. EXAMPLES

[0056] Hereinafter, the present embodiment will be described in more detail with reference to examples and comparative examples, but the present embodiment is not limited thereto. In addition, "parts" and "%" are based on mass unless otherwise specified.

[0057] Details of the components used in making the agricultural film are as follows: <1. Ethylene-vinyl acetate copolymer (EVA)> (EVA-1): Content of structural units derived from vinyl acetate (VA content): 19% by mass MFR (JIS K7210-1999, 190℃, load 2160g) 15g / 10 minutes

[0058] <2. Polyolefin (PO)> (PO-1): Product name: Braskem SGF4950 Type: High density polyethylene (HDPE) Density: (JIS K 7112-1999) 956kg / m 3 MFR: (JIS K 7210-1999, 190℃, load 2160g) 0.34g / 10 minutes Biomass content: 96% by mass (PO-2): Type: High density polyethylene (HDPE) Density: (JIS K7112-1999) 944kg / m 3 MFR: (JIS K7210-1999, 190℃, load 2160g) 0.4g / 10 minutes Biomass content: 0% by mass (PO-3): Type: High density polyethylene (HDPE) Density: (JIS K7112-1999) 940kg / m 3 MFR: (JIS K7210-1999, 190℃, load 2160g) 0.45g / 10 minutes Biomass content: 0% by mass

[0059] [Example 1] (Production of agricultural films) The following ingredients were prepared: <Ingredients> ·EVA-1:50 parts by mass ·PO-1:12 parts by mass ·PO-1:38 parts by mass

[0060] -Preparation of the mixture- The above components were melt-blended using a single screw extruder (extruder screw diameter: 40 mm) under conditions of a die temperature of 180° C. and a melting zone temperature of 180° C., and stable granulation was possible. The content of structural units derived from vinyl acetate (unit: mass %, referred to as VA content in Table 1) and MFR of the mixture after melt blending were measured by the methods described above. The results are shown in Table 1. In addition, blank spaces in Table 1 indicate that the corresponding ingredient is not contained.

[0061] -Molding- The above melt-blended mixture was molded into a tube using a single-layer inflation molding machine (diameter 50 mm, extruder screw diameter 30 mm) under conditions of a die temperature of 180°C, a melt zone temperature of 180°C, a LS (line speed) of 4.0 m / min, and a BUR (blow-up ratio) of 2.1 to form a mixture layer, resulting in an agricultural film with a folded diameter of 260 mm and a thickness of 50 μm.

[0062] [evaluation] The obtained agricultural films were evaluated for the following items. The results are shown in Table 1.

[0063] -Total light transmittance- The total light transmittance of the obtained agricultural film was measured using a haze meter (manufactured by Suga Test Instruments Co., Ltd.) in accordance with JIS-K7136 (2000), and was used as an index for evaluating the light transmittance of the agricultural film. The total light transmittance is preferably 85% or more and less than 95%, and was given an A rating.

[0064] -Hayes- The haze of the obtained agricultural film was measured using a haze meter (manufactured by Suga Test Instruments Co., Ltd.) in accordance with JIS-K7136 (2000), and was used as an index for evaluating the degree of matte finish of the agricultural film. A haze of 70% or more and less than 95% was preferable, and was rated A.

[0065] -Breaking stress- The obtained agricultural film was measured according to JIS-K6760:1995, with the machine axis direction being the MD direction and the direction perpendicular to the machine axis being the TD direction. If the breaking stress was 18 MPa or more (MD direction) or 18 MPa or more (TD direction), it was judged that the breaking stress in the MD direction or TD direction was excellent, and was given an evaluation of A.

[0066] -Elongation at break- The obtained agricultural film was measured according to JIS-K6760:1995, with the machine axis direction being the MD direction and the direction perpendicular to the machine axis being the TD direction. If the elongation at break was 600% or more (MD direction) or 600% or more (TD direction), it was judged that the elongation at break in the MD direction or TD direction was excellent, and was given an evaluation of A.

[0067] [Examples 2 to 6, Comparative Example 1] An agricultural film was produced in the same manner as in Example 1, except that the composition of the agricultural film was changed according to Table 1. The obtained agricultural film was then evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0068] [Table 1]

[0069] As can be seen from Table 1, although the agricultural film of this example contains raw materials derived from biomass, the optical properties (total light transmittance, haze) and mechanical strength (stress at break, elongation at break) were equivalent to those of the agricultural film of Comparative Example 1, which used only raw materials derived from fossil fuels.

Claims

1. An ethylene-vinyl acetate copolymer (A), A polyolefin (B); A mixture layer containing The agricultural film, wherein the mixture layer has a biomass content of more than 0 mass % and not more than 100 mass %, as measured in accordance with ASTM D6866.

2. 2. The agricultural film according to claim 1, wherein the ethylene-vinyl acetate copolymer (A) has a content of structural units derived from vinyl acetate of 12% by mass or more and 35% by mass or less.

3. The agricultural film according to claim 1 or 2, wherein the ethylene-vinyl acetate copolymer (A) has a melt flow rate (MFR, JIS K 7210-1999, 190° C., 2160 g load) of 4 g / 10 min or more and 100 g / 10 min or less.

4. The agricultural film according to any one of claims 1 to 3, wherein the polyolefin (B) comprises at least one selected from the group consisting of high density polyethylene and metallocene-catalyzed polyethylene.

5. The agricultural film according to claim 4 , further comprising a low-density polyethylene as the polyolefin (B).

6. The agricultural film according to any one of claims 1 to 5, wherein the content ratio of the ethylene-vinyl acetate copolymer (A) and the polyolefin (B) in the mixture layer [(A):(B)] is 35:65 to 85:15 in terms of mass ratio.

7. The agricultural film according to any one of claims 1 to 6, wherein the average content of the structural units derived from vinyl acetate is 1% by mass or more and less than 30% by mass when the resin component in the mixture layer is taken as 100% by mass.

8. The agricultural film according to any one of claims 1 to 7, wherein the mixture layer is an outermost layer.

9. MFR of the ethylene-vinyl acetate copolymer (A) Ａ and the MFR of the polyolefin (B) Ｂ The ratio of (MFR Ａ / M.F.R. Ｂ 9. The agricultural film according to claim 1, wherein the molecular weight distribution (Mg / m2) is 10 or more and 100 or less.

10. The agricultural film according to any one of claims 1 to 9, wherein the ethylene-vinyl acetate copolymer (A) comprises a biomass ethylene-vinyl acetate copolymer obtained by polymerizing a monomer containing ethylene derived from biomass.

11. The agricultural film according to any one of claims 1 to 10, wherein the polyolefin (B) comprises a biomass polyolefin obtained by polymerizing a monomer containing ethylene derived from biomass.

12. The agricultural film according to any one of claims 1 to 11, wherein a total content of the ethylene-vinyl acetate copolymer (A) and the polyolefin (B) is 2% by mass or more and 100% by mass or less, when the entire mixture layer is taken as 100% by mass.

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