JP2018062115A - Silage film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a silage film having high wrapping properties (stretchability) and also having easily-bag-breaking properties.SOLUTION: A silage film has, on at least one face of a saponified ethylene/vinyl ester copolymer layer, a hydrophobic thermoplastic resin layer through an adhesive resin layer. The hydrophobic thermoplastic resin layer contains a saponified ethylene/vinyl ester copolymer. For the concentrations of the saponified ethylene/vinyl ester copolymer in the hydrophobic thermoplastic resin layer, a surface layer closest to the saponified ethylene/vinyl ester copolymer layer is higher in concentrations than a surface layer farthest from the saponified ethylene/vinyl ester copolymer layer, and a difference of concentration between them is 0.1-10 wt.%.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a silage film, and more particularly to a silage film having a saponified ethylene-vinyl ester copolymer layer.

  Conventionally, it has been common to use a tower-type silo to create silage that is used as livestock feed from pasture. However, the tower silo is large in scale and takes a lot of labor to pack grass, so both the workload and the economic burden are large. Therefore, in recent years, a simple silo using a thermoplastic resin film has become widespread.

  For example, a bunker silo that cuts the slopes of a hilly area, puts concrete on it, spreads grass and other materials, and covers the top with a thermoplastic resin film; digs a hole in the ground, and lays a wall with concrete or wood An underground type (or semi-underground type) silo where grass is laid and covered with a thermoplastic resin film; a bag silo in which a material is packed and sealed in a large bag made of a thermoplastic resin film; thermoplastic Tube silo that can be packed with high density using a dedicated machine using a resin tube; Stack silo that deposits material on the ground and covers it with a sheet; Combines harvested grass with a large machine to form a cylinder (roll bale) Wrap silo that shapes a rectangular parallelepiped (square bale) and wraps the shaped object with a wide thermoplastic film. It is.

  Among them, lap silos are particularly widespread. A wrap silo rolls up shaped grass with a film and hermetically wraps it, so that the amount of oxygen in the film is reduced to anaerobic conditions, and silage is adjusted.

  As a thermoplastic resin film (hereinafter referred to as silage film) used in such a simple silo, a technique using an ethylene-vinyl ester copolymer saponified product (hereinafter sometimes referred to as EVOH) is known. . For example, the blending ratio of an ethylene-vinyl acetate copolymer saponified product having an ethylene content of 20 to 60 mol% and an ethylene-vinyl acetate copolymer saponified product (B) having an ethylene content of 70 mol% or more is a weight ratio. A silage film having at least one resin composition layer (A) / (B) = 99/1 to 70/30 is known (see Patent Document 1).

  Such EVOH is a thermoplastic resin having abundant hydroxyl groups in the polymer side chain, and since such hydroxyl groups are hydrogen-bonded, it has the characteristics of high crystallinity and high intermolecular force even in an amorphous part. Excellent gas barrier properties. Therefore, when producing silage using the silage film using such EVOH, generation of mold is suppressed.

  Moreover, 3-15 mass% of hydroxyl-containing compounds whose molecular weight is 200 or less with respect to EVOH, the day of the number of hydroxyl groups in 1 molecule with respect to molecular weight is the range of 0.02-0.03, and melting | fusing point is 23 degreeC or more. A silage film having a high oxygen barrier property and stretchability (wrapping suitability) is known (see Patent Document 2).

JP 2011-046929 A International Publication No. 2016/84840

  In particular, in a wrap silo, a higher lapping property (stretchability) is required for the purpose of wrapping a lump of grass, which is difficult to break and at the same time wraps with good adhesion. On the other hand, since multiple films are wound around the lump of grass, opening after silage creation tends to be troublesome, and a function to easily break the bag has been demanded. Thus, there were conflicting performance requirements.

  As a result of intensive studies in view of the above circumstances, the present inventors have found that in a silage film having a hydrophobic thermoplastic resin layer on at least one surface of an EVOH layer via an adhesive resin layer, the hydrophobic thermoplastic resin layer contains EVOH. In addition, in the thickness direction of the silage film, the concentration of the EVOH closest to the EVOH layer of the hydrophobic thermoplastic resin is set higher within a specific range than the concentration farthest from the EVOH layer. I found out to solve it.

  That is, the gist of the present invention is that at least one surface of the saponified ethylene-vinyl ester copolymer layer has a hydrophobic thermoplastic resin layer via an adhesive resin layer, and the hydrophobic thermoplastic resin layer is The saponified ethylene-vinyl ester copolymer contains the saponified ethylene-vinyl ester copolymer in the concentration of the saponified ethylene-vinyl ester copolymer in the hydrophobic thermoplastic resin layer. A silage film characterized in that the near surface layer has a higher concentration than the surface layer farthest from the ethylene-vinyl ester copolymer saponified material layer, and the concentration difference is 0.1 to 10% by weight. Exist.

  The silage film of the present invention has a high wrapping property (stretchability) that is difficult to break when lapping a lump of grass, and can be wrapped with good adhesion, by having the layer structure as described above, and After the silage was created, it became possible to provide a silage film having easy tearability that can be easily opened by breaking the film when opened.

  With the silage film of the present invention having the above-described configuration, EVOH having the same elastic modulus characteristic is within a specific range around the EVOH layer that is relatively stiffer than the hydrophobic thermoplastic resin layer in the thickness direction of the silage film. By making it exist in high concentration, the EVOH layer can be moderately reinforced and can have moderate flexibility as a silage film, and both high wrapping properties (stretchability) and easy bag breaking properties can be achieved. Presumed to be.

FIG. 1 is a schematic cross-sectional view showing a configuration of an embodiment of a silage film according to the present invention. FIG. 2 is a schematic cross-sectional view showing the configuration of another embodiment of the silage film according to the present invention.

Hereinafter, although it demonstrates in detail about the structure of this invention, these show an example of a desirable embodiment.
First, each layer used in the silage film of the present invention will be described.

[Explanation of EVOH layer]
The EVOH layer which the silage film of the present invention has will be described. The EVOH layer is a layer mainly composed of EVOH, and usually more than 50% by weight of the EVOH layer is EVOH. Preferably it is 70-100 weight%, Most preferably, 75-90 weight% is EVOH.
Such EVOH is a known water-insoluble thermoplastic resin having gas barrier properties, and can be obtained by saponifying a copolymer of ethylene and a vinyl ester monomer. The ethylene-vinyl ester copolymer is produced by any known polymerization method, for example, solution polymerization, suspension polymerization, emulsion polymerization, etc., and the ethylene-vinyl ester copolymer is saponified by a known method. obtain. Such a vinyl ester monomer is typically vinyl acetate.

  The ethylene content of EVOH used in the present invention is that the content of ethylene structural units measured based on ISO 14663 is 20 to 60 mol%. And preferably it is 25-55 mol%, More preferably, it is 35-50 mol%, Most preferably, it is 38-48 mol%. When there is too little content of an ethylene structural unit, it exists in the tendency for the softness | flexibility of a film to fall. On the other hand, when the content of the ethylene structural unit is too high, the gas barrier property tends to be insufficient.

  The saponification degree of the vinyl ester component is a value measured based on JIS K6726 (however, EVOH resin is a solution uniformly dissolved in water / methanol solvent), and is usually 95 mol% or more, more preferably. Is 95 to 100 mol%, more preferably 98 to 100 mol%. This is because as the saponification degree decreases, the gas barrier property tends to decrease.

  Furthermore, in the melt flow rate (MFR) of EVOH, it is usually 0.1 to 100 g / 10 minutes, preferably 0.5 to 50 g / 10 minutes, particularly preferably at 210 ° C. and a load of 2160 g. 1-20 g / 10 min. If the MFR value is too small, the torque tends to be too high during extrusion molding, or vertical streaks tend to occur in the resulting film. On the other hand, if the MFR value is too large, the extrusion moldability becomes unstable. Or the film thickness of the resulting film tends to vary.

As the EVOH used in the present invention, two or more kinds different in ethylene content, saponification degree, and MFR may be mixed and used as long as the EVOH satisfies the above requirements.
Further, as EVOH used in the present invention, a small amount of propylene, isobutene, α-octene, α-dodecene, α-olefins such as α-octadecene, 3-buten-1-ol, 4- Hydroxyl group-containing α-olefins such as penten-1-ol, 3-butene-1,2-diol and the like, esterified products, acylated products such as hydroxy group-containing α-olefin derivatives, unsaturated carboxylic acids or salts / parts thereof Copolymers of co-monomers such as alkyl esters, complete alkyl esters, nitriles, amides, anhydrides, unsaturated sulfonic acids or salts thereof, vinyl silane compounds, vinyl chloride, and styrene may be used. Furthermore, it may be “post-modified” such as urethanization, acetalization, cyanoethylation, oxyalkyleneation, and epoxidation.
In particular, EVOH copolymerized with hydroxy group-containing α-olefins is preferable in terms of good moldability and stretchability, and EVOH resin having 1,2-diol in the side chain is particularly preferable.

  In the EVOH used in the present invention, a compounding agent generally blended in advance with EVOH in a range not inhibiting the effect of the present invention, such as a heat stabilizer, an antioxidant, an antistatic agent, a colorant, an ultraviolet absorber, a lubricant. , Plasticizer, light stabilizer, surfactant, antibacterial agent, drying agent, antiblocking agent, flame retardant, crosslinking agent, curing agent, foaming agent, crystal nucleating agent, antifogging agent, biodegradation additive, silane cup A ring agent, an oxygen absorber, etc. may be contained.

  The heat stabilizer is an organic acid such as acetic acid, propionic acid, butyric acid, lauric acid, stearic acid, oleic acid, behenic acid, or an alkali thereof for the purpose of improving various physical properties such as heat stability during melt molding. A salt such as an earth metal salt (sodium, potassium, etc.), an alkaline earth metal salt (calcium, magnesium, etc.), a metal salt (zinc, copper, etc.) belonging to the fourth block d of the periodic table; or sulfuric acid, sulfurous acid Inorganic acids such as carbonic acid, phosphoric acid and boric acid, or alkaline earth metal salts thereof (sodium, potassium, etc.), alkaline earth metal salts (calcium, magnesium, etc.), belonging to the 4th period d block of the periodic table Additives such as salts such as metal salts (zinc, copper, etc.) may be added. Among these, it is particularly preferable to add boron compounds, acetates, and phosphates including acetic acid, phosphoric acid, boric acid and salts thereof.

  When acetic acid is added, the amount added is usually 0.001 to 1 part by weight, preferably 0.005 to 0.2 part by weight, particularly preferably 0.01 to 0.1 part by weight based on 100 parts by weight of EVOH. It is. If the amount of acetic acid added is too small, the effect of acetic acid content tends not to be sufficiently obtained, and conversely if too large, it tends to be difficult to obtain a film having a uniform thickness and appearance.

  When phosphoric acid is added, the amount added is usually 0.0005 to 0.1 parts by weight with respect to 100 parts by weight of EVOH (analyzed by thermal decomposition with sulfuric acid and nitric acid and analyzing phosphate groups by atomic absorption method), preferably 0.001 to 0.05 part by weight, particularly preferably 0.002 to 0.03 part by weight. If the amount of phosphoric acid added is too small, the phosphoric acid-containing effect tends to be insufficient, and conversely if too large, it tends to be difficult to obtain a film having a uniform thickness and appearance.

  When a boron compound is added, the amount added is usually 0.001 to 1 part by weight in terms of boron (analyzed by ICP emission spectrometry after ashing) with respect to 100 parts by weight of EVOH, preferably 0. 0.002 to 0.2 part by weight, particularly preferably 0.005 to 0.1 part by weight. If the addition amount of the boron compound is too small, the effect of adding the boron compound may not be sufficiently obtained. Conversely, if the addition amount is too large, it tends to be difficult to obtain a film having a uniform thickness and appearance.

  The amount of acetate and phosphate (including hydrogen phosphate) added is usually 0.0005 to 0 in terms of metal (after ashing and analyzed by ICP emission spectrometry) with respect to 100 parts by weight of EVOH. 0.1 part by weight, preferably 0.001 to 0.05 part by weight, particularly preferably 0.002 to 0.03 part by weight. If the added amount is too small, the content effect may not be sufficiently obtained. Conversely, if the added amount is too large, the resulting film tends to be colored or odorous. In addition, when adding 2 or more types of salts to EVOH, it is preferable that the total amount exists in the range of said addition amount.

[Saponified ethylene-vinyl acetate copolymer having an ethylene content of 70 mol% or more]
The EVOH layer in the silage film of the present invention preferably contains a saponified ethylene-vinyl acetate copolymer having an ethylene content of 70 mol% or more (hereinafter, this component may be referred to as high ethylene EVOH). . By using such high ethylene EVOH, there is a tendency that the puncture strength and tensile elongation are good without impairing the gas barrier properties of EVOH.
Such high ethylene EVOH is obtained by saponifying a vinyl acetate component of an ethylene-vinyl acetate copolymer having an ethylene content of 70 mol% or more, and is different from EVOH in ethylene content.

  The high ethylene EVOH is produced by saponifying ethylene and vinyl acetate by any known polymerization method such as solution polymerization, suspension polymerization, emulsion polymerization, and the like. The ethylene content of the high ethylene EVOH is such that the content of the ethylene structural unit measured based on ISO 14663 is 70 mol% or more, and the upper limit is usually 98 mol% or less. The ethylene content is preferably 75 to 95 mol%, more preferably 80 to 95 mol%. When there is too little ethylene content, it exists in the tendency for the improvement effect of piercing strength and tensile breaking elongation to fall.

  Moreover, as a saponification degree of the said high ethylene EVOH, it is the value measured based on JISK6726, and is 20 mol% or more normally, Preferably it is 40-100 mol%, Most preferably, it is 80-100 mol%. When the saponification degree is too low, the affinity with EVOH decreases, and the film appearance tends to deteriorate, and the effect of improving the puncture strength and tensile break elongation tends to be insufficient.

  The melt flow rate (MFR) (190 ° C., load 2160 g) of the high ethylene EVOH is usually 0.5 to 100 g / 10 minutes, preferably 1 to 50 g / 10 minutes, more preferably 2 to 30 g / 10. It is preferable that it is a minute in terms of excellent dispersibility and excellent effects of the present invention.

The density of the high ethylene EVOH is usually 500 to 1500 kg / m ³ , preferably 800 to 1200 kg / m ³ , particularly preferably 900 to 1100 kg / m ³ .

  The high ethylene EVOH may be copolymerized with another copolymerizable monomer similar to the EVOH resin as long as the gist of the present invention is not impaired.

  The high ethylene EVOH is a modified product containing a carboxyl group obtained by chemically bonding an unsaturated carboxylic acid or an anhydride thereof by an addition reaction or a graft reaction within a range that does not impair the gist of the present invention. Also good. For example, the amount of modification is preferably 10 mol% or less. Examples of the unsaturated carboxylic acid or anhydride thereof include ethylenically unsaturated monocarboxylic acids such as acrylic acid, methacrylic acid, ethacrylic acid, and crotonic acid, fumaric acid, itaconic acid, citraconic acid, maleic acid, and maleic acid. Examples thereof include ethylenically unsaturated dicarboxylic acids such as monomethyl, monoethyl maleate, and maleic anhydride, anhydrides thereof, half esters, etc. Among them, maleic anhydride is preferably used.

  In the high ethylene EVOH used in the present invention, in the range that does not inhibit the effect of the present invention, a compounding agent generally blended in advance with a thermoplastic resin, for example, a heat stabilizer, an antioxidant, an antistatic agent, a colorant, UV absorbers, lubricants, plasticizers, light stabilizers, surfactants, antibacterial agents, drying agents, antiblocking agents, flame retardants, crosslinking agents, curing agents, foaming agents, crystal nucleating agents, antifogging agents, for biodegradation Additives, silane coupling agents, oxygen absorbers and the like may be contained.

  The high ethylene EVOH can be used in combination of two or more kinds of high ethylene EVOH having different ethylene contents, saponification degree, molecular weight, MFR, density, modified group and modified amount within the above range.

[Combination ratio]
When the EVOH layer used in the silage film of the present invention contains high ethylene EVOH, the blending ratio is usually 1 to 40% by weight in terms of the weight ratio of high ethylene EVOH to the sum of EVOH and high ethylene EVOH, more preferably 1 It is -30 wt%, More preferably, it is 5-25 wt%, More preferably, it is 10-28 wt%, More preferably, it is 15-25 wt%.
By blending EVOH as a main component and high ethylene EVOH, it is possible to improve the puncture strength and tensile elongation at break while maintaining excellent gas barrier properties.

[Other ingredients]
In the EVOH layer, a thermoplastic resin or addition other than the above EVOH or high ethylene EVOH is added within a range not impairing the effects of the present invention (for example, usually less than 20% by weight, preferably 1 to 10% by weight of the resin composition). An agent may be contained.
Examples of thermoplastic resins other than the high ethylene EVOH include polyolefin resins; ethylene-vinyl acetate copolymer resins; vinyl ester resins; polyester resins; polyamide resins; polystyrene resins; Resin, ethylene-vinyl acetate copolymer resin, carboxyl group-containing resin obtained by addition reaction or graft reaction of unsaturated carboxylic acid such as maleic acid to vinyl ester resin, etc., among others, carboxyl group-containing ethylene-acetic acid A vinyl copolymer resin is preferred.
Examples of the additive include an antioxidant, a lubricant, an antistatic agent, a colorant, an ultraviolet absorber, a plasticizer, a heat stabilizer, a light stabilizer, a surfactant, an antibacterial agent, a desiccant, an antiblocking agent, and a difficult agent. Examples include a flame retardant, a crosslinking agent, a curing agent, a foaming agent, a crystal nucleating agent, an antifogging agent, a biodegradation additive, a silane coupling agent, and an oxygen absorber.

[Hydrophobic thermoplastic resin layer]
The hydrophobic thermoplastic resin layer constituting the silage film of the present invention is provided for the purpose of preventing the gas barrier performance of the EVOH layer from being lowered by moisture. The hydrophobic thermoplastic resin in the hydrophobic thermoplastic resin layer means a thermoplastic resin other than EVOH and an adhesive resin.

For example, specifically, polyolefin resins: linear low-density polyethylene, low-density polyethylene, ultra-low-density polyethylene, ultra-low-density linear polyethylene, medium-density polyethylene, high-density polyethylene, and the like (each made of metallocene catalyst) ), And polyethylene resins such as ethylene-α olefin copolymers, polypropylene, ethylene-propylene (block and random) copolymers, propylene-α-olefin (α-olefins having 4 to 20 carbon atoms) copolymer Polypropylene resins such as coalescence, polybutene, polypentene, etc .; grafted polyolefins obtained by graft-modifying these polyolefins with unsaturated carboxylic acids or esters thereof, cyclic polyolefin resins; ionomers, ethylene-vinyl acetate copolymers, ethylene-acrylics Copolymer, ethylene-acrylic ester copolymer, polyester resin, polyamide resin (including copolymer polyamide), polyvinyl chloride, polyvinylidene chloride, acrylic resin, polystyrene, vinyl ester resin, polyester elastomer, Examples include polyurethane elastomers, halogenated polyolefins such as chlorinated polyethylene and chlorinated polypropylene, and aromatic or aliphatic polyketones.
A resin having no polar bond such as a hydroxyl group, a carboxyl group, or a polar group such as a hydroxyl group or a carboxyl group in terms of high hydrophobicity is preferred. Among them, a polyolefin resin is more preferred in terms of mechanical strength and moldability. Particularly preferred are polyethylene and polypropylene.

  In particular, in order to improve the piercing strength and tensile breaking strength of the film, use at least one kind of ultra-low density linear polyethylene, low density linear polyethylene made of metallocene catalyst, polyolefin plastomer together with low density polyethylene. Is preferred.

The melt flow rate (MFR) of the hydrophobic thermoplastic resin is usually from 0.1 to 100 g / 10 minutes, preferably from 0.5 to 50 g / 10 minutes under the conditions of 210 ° C. and a load of 2160 g, Preferably it is 0.5-20 g / 10min. If the MFR value is too small, the torque tends to be too high during extrusion molding, or vertical streaks tend to occur in the resulting film. On the other hand, if the MFR value is too large, the extrusion moldability becomes unstable. Or the film thickness of the resulting film tends to vary. Moreover, the one where the difference with MFR of EVOH resin composition is smaller is preferable.
The melting point of the hydrophobic thermoplastic resin is usually 150 to 300 ° C.

  In the silage film of the present invention, such a hydrophobic thermoplastic resin layer contains EVOH, and the EVOH concentration on the side surface closest to the EVOH layer of the hydrophobic thermoplastic resin in the thickness direction of the silage film is the same EVOH layer. It is characterized in that it is higher within a specific range than the concentration of the side surface farthest.

  By having such a configuration, EVOH having the same hardness exists in the hydrophobic thermoplastic resin layer at a high concentration around the EVOH layer that is relatively stiffer than the hydrophobic thermoplastic resin layer. Is presumably moderately reinforced by the EVOH component in the hydrophobic thermoplastic resin layer. At the same time, since the EVOH concentration on the side surface farthest from the EVOH layer of the hydrophobic thermoplastic resin layer is relatively lower than that on the nearest side surface, it becomes possible to have moderate flexibility as a silage film. It is presumed that when the plastic resin layer has EVOH in such a concentration balance, both high wrapping properties (stretchability) and easy bag breaking properties can be achieved.

  In the thickness direction of the silage film of the present invention, the EVOH concentration on the side surface closest to the EVOH layer of the hydrophobic thermoplastic resin should be higher in a specific range than the concentration on the side surface farthest from the EVOH layer. The EVOH concentration on the farthest side surface may be 0% by weight, that is, a hydrophobic thermoplastic resin layer containing no EVOH.

  EVOH used for the EVOH layer may be used for EVOH included in the hydrophobic thermoplastic resin layer. Moreover, as such EVOH, ethylene content, a saponification degree, MFR, etc. may be the same or different from EVOH used for an EVOH layer.

  In the silage film of the present invention, as a method for changing the content concentration of the EVOH in the hydrophobic thermoplastic resin layer, for example, a plurality of hydrophobic thermoplastic resin compositions having different EVOH content concentrations are prepared, and the EVOH layer On the side, an EVOH high-concentration hydrophobic thermoplastic resin layer obtained by a hydrophobic thermoplastic resin composition having a high EVOH content concentration within a specific range is provided, and obtained by a hydrophobic thermoplastic resin composition having a low EVOH content concentration. A method of forming a silage film by positioning the EVOH low-concentration hydrophobic thermoplastic resin layer on the opposite side of the EVOH layer through the EVOH high-concentration hydrophobic thermoplastic resin layer can be mentioned.

For example, when the hydrophobic thermoplastic resin layer is formed of two kinds of hydrophobic thermoplastic resin compositions, as shown in FIG. 1, EVOH obtained by the hydrophobic thermoplastic resin composition having a high EVOH content concentration The high-concentration hydrophobic thermoplastic resin layer 2a is placed on the EVOH layer 1 side, and the EVOH low-concentration hydrophobic thermoplastic resin layer 2b obtained from the hydrophobic thermoplastic resin composition having a low EVOH concentration is used as the EVOH high-concentration hydrophobic heat. A method of forming the hydrophobic thermoplastic resin layer 2 by placing it on the opposite side of the EVOH layer via the plastic resin layer 2a can be mentioned. In the case where the hydrophobic thermoplastic resin layer 2 is formed of three or more hydrophobic thermoplastic resin compositions, the EVOH concentration in the hydrophobic thermoplastic resin layer forming the EVOH layer side surface layer is the same EVOH. If the concentration of EVOH in the hydrophobic thermoplastic resin layer forming the surface layer opposite to the layer is higher within a specific range, the content of the thermoplastic elastomer in the intermediate layer is the base film (A) It may be higher or lower than the concentration of the side surface layer.
As described above, the hydrophobic thermoplastic resin layer in the present invention can be composed of a single layer or multiple layers. From the viewpoint of easy adjustment of the EVOH content concentration in the hydrophobic thermoplastic resin layer, a multilayer structure is preferable.

  In the present invention, the difference between the EVOH concentration on the side surface closest to the EVOH layer of the hydrophobic thermoplastic resin layer and the concentration on the side surface farthest from the EVOH layer is 0.1 to 10% by weight, preferably 0.8. It is 3 to 5% by weight, particularly preferably 0.5 to 3% by weight. When the difference between the EVOH concentration on the side surface closest to the EVOH layer of the hydrophobic thermoplastic resin layer and the concentration on the side surface farthest to the EVOH layer is within the above range, high lapping characteristics (stretchability) and easy breakage in the silage film. There exists a tendency which can make bag nature compatible.

  Further, the EVOH concentration on the side surface closest to the EVOH layer of the hydrophobic thermoplastic resin layer is usually 0.1 to 10% by weight, preferably 0.3 to 5% by weight, particularly in the hydrophobic thermoplastic resin layer. Preferably it is 0.5 to 2 weight%. When such a concentration is too high, high lapping characteristics (stretchability) tend to decrease, and when it is too low, easy bag breaking property tends to decrease.

  The EVOH concentration on the surface of the hydrophobic thermoplastic resin layer farthest from the EVOH layer is usually 0 to 10% by weight, preferably 0 to 5% by weight, particularly preferably 0 to 0% in the hydrophobic thermoplastic resin layer. 3% by weight, most preferably 0% (excluding EVOH). When the concentration is in the above range, the effect of the present invention tends to be effectively obtained.

  Thus, when the content concentration of EVOH in the hydrophobic thermoplastic resin layer is changed using a layer composed of a plurality of hydrophobic thermoplastic resin compositions, the hydrophobic thermoplastic resin composition containing the EVOH is used. All layers are considered hydrophobic thermoplastic layers.

  The hydrophobic thermoplastic resin layer in the present invention may be a hydrophobic thermoplastic resin composition film containing EVOH or a coating film thereof.

  In addition, it is preferable to mix | blend an ultraviolet-resistant agent and an adhesive component with said hydrophobic thermoplastic resin. Examples of UV-resistant agents include UV absorbers (specifically, benzotriazole-based UV absorbers, benzophenone-based UV absorbers, salicylate-based UV absorbers, cyanoacrylate-based UV absorbers, and oxanilide-based UV absorbers). Agents (specifically, hindered amine light stabilizers, nickel light stabilizers, benzoate light stabilizers), colorants, etc., and the use of UV absorbers in combination with light stabilizers inhibits chain initiation. Since a synergistic effect as an agent and a radical scavenger is obtained, it is preferable.

  The blending amount of the UV-resistant agent is usually 1 to 10% by weight, preferably 2 to 8% by weight, and particularly preferably 3 to 5% by weight with respect to the hydrophobic thermoplastic resin. When the blending amount is too small, the hydrophobic thermoplastic resin is likely to be deteriorated by ultraviolet rays, but as the blending amount is increased, the ultraviolet resistance effect is not necessarily improved in proportion.

  Examples of the adhesive component include aliphatic saturated hydrocarbon resins such as polyisobutene, alicyclic saturated hydrocarbon resins, and the like, and usually 1 to 30% by weight, preferably based on the hydrophobic thermoplastic resin. It is 2 to 22% by weight, particularly preferably 5 to 20% by weight. When such a blending amount is appropriate, the films are pressure-bonded when the silage is covered with the film of the present invention, and are easily sealed, and the films are hardly peeled off. If the amount is too small, the film peels off and a gap is generated, and the risk of air flowing into the silo increases. If the amount is too large, the film is blocked, and there is a tendency that defects are likely to occur at the time of winding.

[Adhesive resin layer]
It does not specifically limit as adhesive resin which comprises an adhesive resin layer, What is necessary is just to use well-known adhesive resin. Generally, a modified olefin containing a carboxyl group obtained by chemically bonding an unsaturated carboxylic acid or an anhydride thereof to an olefin polymer (the above-mentioned broadly defined polyolefin resin) by an addition reaction or a graft reaction. Examples thereof include maleic anhydride graft-modified polyethylene, maleic anhydride graft-modified polypropylene, maleic anhydride graft-modified ethylene-ethyl acrylate copolymer, maleic anhydride graft-modified ethylene-vinyl acetate. One or a mixture of two or more selected from copolymers and the like is preferred. Such an adhesive resin is not included in the hydrophobic thermoplastic resin in the hydrophobic thermoplastic resin layer.

[Arbitrary layer]

  In addition to these resin layers, the silage film of the present invention includes paper, metal foil, uniaxial or biaxially stretched plastic film or sheet, woven fabric, non-woven fabric, metal cotton strip, wood surface, aluminum and silica vapor deposition. You may have combined layers.

<Silage film>

  The silage film of the present invention has the hydrophobic thermoplastic resin layer on at least one surface of the EVOH layer via the adhesive resin layer. The hydrophobic thermoplastic resin layer contains EVOH, and the layer surface closest to the EVOH layer in the concentration of EVOH in the hydrophobic thermoplastic resin layer is specified more than the layer surface farthest from the EVOH layer. It is characterized by a high concentration within the range.

When silage is produced using a silage film using EVOH, mold generation tends to be suppressed due to the high gas barrier property of EVOH. On the other hand, since the gas barrier property of EVOH decreases due to the presence of moisture, the silage film of the present invention sandwiches the EVOH layer through the adhesive resin layer with a hydrophobic thermoplastic resin layer having an excellent water barrier property. A multilayer structure having a configuration is preferably used. That is, in the silage film of the present invention, the hydrophobic thermoplastic resin layer sandwiches the EVOH layer via the adhesive resin layer, and the hydrophobic thermoplastic resin layer on at least one surface of the EVOH layer satisfies the above conditions. It is preferable to satisfy.
Further, when the EVOH layer is sandwiched between the hydrophobic thermoplastic resin layers via the adhesive resin layer and the hydrophobic thermoplastic resin layers on both sides of the EVOH layer satisfy the above conditions, the effects of the present invention are obtained. It is preferable at the point obtained more effectively.

The layer structure of the silage film of the present invention is generally 3 to 20 layers, preferably 3 to 15 layers, particularly preferably EV EV layer is L _E , the adhesive resin layer is a and the hydrophobic thermoplastic resin layer is b. Is 5 to 10 layers. Among them, the EVOH layer is usually one layer from the viewpoint of economy and gas barrier properties.

For example, _{specifically, b / a / L E,} b / a / L E / a / b, b / a / L E / a / b / b, b / b / a / L E / a / b / b, b / b / b / a / L E / a / b / b / b , etc. any combination is possible.
A recycle layer containing a mixture of a resin composition and a hydrophobic thermoplastic resin other than EVOH, which is obtained by remelt molding of edges and defective products generated in the process of producing the multilayer structure, may be provided.

  Among the above, using a hydrophobic thermoplastic resin having two types of EVOH concentrations differing in productivity, an EVOH high-concentration hydrophobic thermoplastic resin layer obtained by a hydrophobic thermoplastic resin composition having a high EVOH concentration 2a, when the EVOH high-concentration hydrophobic thermoplastic resin layer obtained by the hydrophobic thermoplastic resin composition having a low EVOH content concentration is 2b, the hydrophobic thermoplastic resin layer (2b) / Hydrophobic thermoplastic resin layer (2a) / adhesive resin layer (3) / EVOH layer (1) / adhesive resin layer (3) / hydrophobic thermoplastic resin layer (2a) / hydrophobic thermoplastic resin layer (2b) It is most preferable to use a multilayer structure having the structure of

<Manufacturing method of silage film>
The production method of the silage film of the present invention is roughly classified into a method of molding EVOH in a melted state (melt molding method), a method of molding EVOH in a solvent (for example, solution coating method), and the like. Among these, the melt molding method is preferable from the viewpoint of productivity.
Specifically, for example, a method in which an adhesive resin and a hydrophobic thermoplastic resin are melt-extruded into an EVOH molded product (for example, a film or a sheet), and an adhesive resin and EVOH are melted in a film or sheet of a hydrophobic thermoplastic resin. Extrusion method, EVOH layer and hydrophobic thermoplastic resin layer may be co-extruded through adhesive resin. T-die extrusion, inflation extrusion, blow molding, profile extrusion, etc. are used in detail. . In particular, when the inflation extrusion method is employed, the blow-up ratio is usually 1 to 10 and preferably 2 to 8 from the viewpoint of the mechanical strength of the silage film.

  As a method for adjusting the EVOH concentration in the hydrophobic thermoplastic resin, a known method may be used. The hydrophobic thermoplastic resin and the EVOH resin may be dry blended, or the hydrophobic thermoplastic resin and the EVOH resin are melted in advance. For example, the pellets may be mixed and used. Further, from the viewpoint of reducing the manufacturing cost, it is also preferable to use a waste film, an end portion, a defective product, or the like of a film having an EVOH layer as an EVOH resin raw material.

  The thickness of the silage film of the present invention is generally 5 to 500 μm, preferably 10 to 300 μm, more preferably 20 to 200 μm, and particularly preferably 20 to 50 μm.

  Moreover, the thickness of the EVOH layer in a silage film is 0.1-100 micrometers normally, Preferably it is 0.5-50 micrometers, Most preferably, it is 0.5-5 micrometers. When the thickness is too thick, the mechanical properties of the film tend to be lowered, and when it is too thin, the gas barrier property tends to be lowered.

  In addition, the thickness of the hydrophobic thermoplastic resin layer in the silage film is usually 0.5 to 200 μm, preferably 1 to 100 μm, particularly preferably the total thickness when there are a plurality of hydrophobic thermoplastic resin layers. Is 10 to 100 μm. Although the thickness of an adhesive resin layer is not specifically limited, Usually, 0.5-50 micrometers, Preferably it is 1-30 micrometers, Most preferably, it is 1-5 micrometers.

  Moreover, when there are a plurality of hydrophobic thermoplastic resin layers in the silage film, the thickness of each layer is usually 0.5 to 100 μm, preferably 1 to 10 μm.

  As for the thickness ratio of the hydrophobic thermoplastic resin layer / the EVOH layer in the silage film of the present invention, it is preferable that the hydrophobic thermoplastic resin layer is thicker for the purpose of suppressing water mixing into the hydrophobic thermoplastic resin. When there are a plurality of layers, the ratio of the sum of the thicknesses of the same layer is usually more than 1 to 200, preferably 2 to 10.

  The thickness ratio of the adhesive resin layer / the EVOH layer in the silage film of the present invention is usually 0.1 to 2, preferably 0.2 to 1, in the ratio of the thinnest layers when there are a plurality of layers. Most preferably, it is 0.2-0.9. In view of productivity, the adhesive resin layer is preferably thinner.

  In particular, as described above, the hydrophobic thermoplastic resin layer (2b) / hydrophobic thermoplastic resin layer (2a) / adhesive resin layer (3) / EVOH layer (1) / adhesive resin layer ( In the case of 3) / hydrophobic thermoplastic resin layer (2a) / hydrophobic thermoplastic resin layer (2b), the thickness ratio of hydrophobic thermoplastic resin layer (2a) / layer (2b) is usually 0.1. -10, preferably 1-5, particularly preferably 2-4. If the thickness ratio is too large, the tear strength of the film tends not to be ensured, and if it is too small, the easy tearability tends to be lost.

  The silage film of the present invention is usually a film which is only laminated with a hydrophobic thermoplastic resin, an adhesive resin, or EVOH as described above, and is not subjected to stretching treatment, but is stretched as necessary. May be.

  In addition, about extending | stretching, a well-known extending | stretching method may be sufficient, for example, uniaxial stretching, biaxial stretching, etc. are mentioned. In the case of biaxial stretching, both a simultaneous biaxial stretching method and a sequential biaxial stretching method can be employed. Examples of the stretching method include tenter stretching and double bubble stretching. The stretching temperature is the temperature of the multilayer structure (the temperature in the vicinity of the multilayer structure) and is usually selected from the range of about 50 to 200 ° C., preferably about 80 to 160 ° C. Since the silage film of the present invention may be stretched at room temperature during silage wrapping, it is better to limit the stretching ratio to the extent that room for room temperature stretching is left later in the main stretching step.

[How to create silage]
The method for producing silage using the silage film of the present invention is not particularly limited.
As the silage raw material, a commonly used raw material is appropriately used, and usually grass. For example, specifically, grasses such as orchardgrass, timothy, perennial ryegrass, italian ryegrass, kentucky bluegrass, tall fescue, sudangrass, straw, etc .; legumes such as white clover, red clover, alfalfa; corn; Other examples include rape grass, wild grass, and vegetable scraps. These may be used alone or in combination of two or more.
In addition, as in all-in silage, concentrated feed such as cereals, bran, soybeans, soybean meal, beer meal, etc., and unused / low-use feed resources such as cereals, bran, soybeans, soybean meal, beer meal, etc. It is also possible to mix the secondary materials together to make silage.
The silage film of the present invention is preferably used for grass silage, and particularly preferably used as a film for packaging silage containing 70 to 99.9% by weight of grass.

As a silage method, a normal silage method is adopted. For example, if necessary, the raw material is dried to an appropriate water content (usually 30 to 70% by weight), and this is subjected to sealing conditions according to various silo shapes.
At this time, if the silage raw material is shredded or stepped on to increase the density of the silage raw material to reduce the amount of oxygen remaining in the film, the activity of aerobic bacteria and the generation of mold are suppressed, which is good. There is a tendency to obtain silage.
The silage may be sealed in various silos as described above, stored under anaerobic conditions, and fermented. Such storage period is usually 1 to 36 months, and further 2 to 24 months.

  The form of the silo using the silage film of the present invention is not particularly limited. For example, a bunker silo, an underground type (or semi-underground type) silo, a bag silo, a tube silo, a stack silo, and a wrap silo. Etc., various forms.

In particular, when creating a wrap silo, first, the grass is shaped to a desired capacity (for example, 0.1 to 50 m ³ , preferably 1 to 30 m ³ ). For example, in the case of a cylindrical roll bale silo, the size is usually 0.5 to 3 m, preferably 1 to 2 m, and the height is usually 0.5 to 3 m, preferably 1 to 2 m.
Then, the silage film of the present invention is wrapped around the shaped grass using an ordinary wrap wrapping machine, and the silage is sealed. When winding such a film on the grass, it is preferable to reduce the air remaining in the silage as much as possible. Therefore, the film is wound while being stretched with tension applied, and the film is adhered to the silage. Is preferred.

Such a draw ratio is usually 1.1 to 5 times, preferably 1.3 to 3 times, and particularly preferably 1.5 to 2 times.
Moreover, the winding frequency of a silage film is 2-10 times normally, Preferably it is 2-8 times, Most preferably, it is 2-5 times.

  The silage film of the present invention has high wrapping properties (stretchability) that it is difficult to break when lapping grass clumps and can be wrapped with good adhesion, and after silage creation, the film should be broken when opened Therefore, it is useful as a film at the time of silage preparation, and is particularly useful for wrap silo use.

  The silaged feed may be fed as it is, or may be adjusted as a mixed feed by adding a concentrated feed with a high protein content such as cereals, bran and soybeans.

EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples. However, the present invention is not limited to the description of the examples unless it exceeds the gist.
In the examples, “parts” and “%” mean weight basis unless otherwise specified.

〔Evaluation method〕
(1) Stretchability (wrapping suitability)
Using the obtained silage film, tensile elasticity, stress at break and elongation at break were measured under the following conditions. The results are shown in Table 1.
Equipment: Autograph AGS-H, manufactured by Shimadzu Corporation
Sample: 15 mm strip (n = 5; the above film cut out in MD / TD direction)
Conditions: Chuck distance 50 mm Tensile speed 500 mm / min Environment: 23 ° C., 50% RH

(2) Easy bag breaking property The easy bag breaking property was measured on the following conditions using the obtained silage film. It means that it is excellent in silage bag breaking work efficiency, so that this value is low. The results are shown in Table 1.
Equipment: Yasuda Seiki Seisakusho Elmendorf tear tester Sample: width 63mm, length 76mm
Conditions: ISO 6383-2 compliant environment: 23 ° C., 50% RH

Example 1
Hydrophobic thermoplastic resin layer (II) / hydrophobic thermoplastic resin layer (I) / adhesive resin layer / EVOH layer / adhesive resin layer / hydrophobic thermoplastic resin layer (I) / hydrophobic thermoplastic resin layer ( II) = silage film having a layer structure of thickness 6 μm / 14 μm / 1 μm / 1 μm / 1 μm / 14 μm / 6 μm (total thickness 43 μm) was prepared.
As the EVOH layer, a saponified ethylene-vinyl acetate copolymer (ethylene content 44 mol%, saponification degree 99.7 mol%, MFR (210 ° C., 2160 g) 3.5 g / 10 min) was used.

  As an adhesive resin, a blend of 10 parts of maleic anhydride-modified polyethylene (Bynel 4140 manufactured by DuPont) and 90 parts of a polyethylene resin (α-olefin-ethylene copolymer) was used.

  As the hydrophobic thermoplastic resin layer (II), a hydrophobic thermoplastic resin composition obtained by dry blending 90 parts of a linear polyethylene resin composition and 10 parts of low density polyethylene was used.

  As the hydrophobic thermoplastic resin layer (I), a multilayer film in which the EVOH resin composition is sandwiched between the hydrophobic thermoplastic resin composition and the hydrophobic thermoplastic resin composition via the adhesive resin ( A resin composition containing 15 wt% of a thickness of 20 μ / 1 μ / 1.5 μ / 1 μ / 20 μ: a total thickness of 43.5 μm was used. At this time, the concentration of the EVOH in the layer (I) was 0.7% by weight.

[Production of silage film]
A silage film having the above structure was formed under the following conditions to obtain a silage film having a width of 750 mm and a total thickness of 43 μm.
Die: 450mm, set temperature 220 ° C
Film take-off speed: 45m / min

Comparative Example 1
In Example 1, only the hydrophobic thermoplastic resin composition layer (II) was used as the hydrophobic thermoplastic resin layer of the silage film, and the hydrophobic thermoplastic resin layer (II) / adhesive resin layer / EVOH layer / Adhesive resin layer / hydrophobic thermoplastic resin layer (II)) = thickness 20 μm / 1 μm / 1 μm / 1 μm / 20 μm (total thickness 43 μm) The same silage film was evaluated in the same manner. The results are shown in Table 1.

In Example 1 using a silage film in which the surface layer closest to the EVOH layer was higher in concentration than the surface layer farthest from the EVOH layer in the concentration of EVOH in the hydrophobic thermoplastic resin layer, tensile elasticity, It was found that the stress at break and the elongation at break were both improved and had excellent stretchability. Furthermore, in terms of work efficiency, the easy bag breaking property was low and an excellent value.
That is, it was found that the silage film of the present invention can achieve both high wrapping properties (stretchability) and easy bag breaking properties.

DESCRIPTION OF SYMBOLS 1 EVOH layer 2 Hydrophobic thermoplastic resin layer 2a EVOH high concentration hydrophobic thermoplastic resin layer 2b EVOH low concentration hydrophobic thermoplastic resin layer 3 Adhesive resin layer

Claims (2)

At least one surface of the saponified ethylene-vinyl ester copolymer layer has a hydrophobic thermoplastic resin layer via an adhesive resin layer,
The hydrophobic thermoplastic resin layer contains an ethylene-vinyl ester copolymer saponified product,
In the concentration of the saponified ethylene-vinyl ester copolymer in the hydrophobic thermoplastic resin layer, the surface layer closest to the saponified ethylene-vinyl ester copolymer layer is the same ethylene-vinyl ester copolymer. A silage film having a higher concentration than the surface layer farthest from the saponified layer and having a concentration difference of 0.1 to 10% by weight. The ratio (T _H / T _E ) between the thickness (T _E ) of the saponified ethylene-vinyl ester copolymer layer and the thickness (T _H ) of the hydrophobic resin layer is 1 to 200. The silage film according to claim 1.

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