JPH0885570A - Bag in box - Google Patents

Abstract

PURPOSE: To contrive the improvement of gas-barrier property and pinhole resisting property by using a material having at least one layer of the composition containing ethylene-vinyl alcohol copolymer and a specific polyolefin or a resin composition with thermoplastic resin added to the first by mentioned composition. CONSTITUTION: The material for use in a bag-in-box has at least one layer of EVOH, a composition containing polyolefin with at least one functional group selected from boric group, borinic group, and boron-containing group capable of conversion into boric acid group or borine group in the presence of water, or of the resin composition with thermoplastic resin added to the first-mentioned composition. The EVOH refers to the saponification product of ethylene-vinyl ester copolymer. As for the thermoplastic resin composition, polyolefin is suited for the production. This resin composition may be used in any one of the intermediate layer, the outermost layer and the innermost layer. As to the resin for use in lamination with the resin composition, the resin good in transparency is generally preferable.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bag-in-box excellent in pin pole resistance and gas barrier property, and more particularly to a container in the bag-in-box.

[0002]

2. Description of the Related Art The function of a flexible laminated packaging material is basically to preserve the material to be packaged, that is, to prevent deterioration of the material. Therefore, the packaging material has, in particular, transport vibration strength and pin pole resistance. It is requested and, in particular, so-called bag-in-box or bag-in-carton (hereinafter, these are collectively referred to as bag-in-box (hereinafter referred to as BIB)).
When used as an inner container (a container that combines a foldable plastic thin-walled inner container with an outer corrugated cardboard box having stackability, portability, and printability),
A high degree of this property is required. The packaging material is used by laminating various plastic films by taking advantage of the characteristics of each material. For example, a combination of a base material film for maintaining mechanical strength and a heat-sealable material is most common. The material is selected according to the request of the object to be packaged. In particular, for the unsatisfactory use of the base film for blocking gas such as oxygen, a barrier layer having a higher gas blocking property is provided on the base layer, and the barrier layer can be heat-sealed as an intermediate layer. A method of laminating a thermoplastic resin layer so that the material is at least one outer layer is adopted.

For example, the basic material of the conventional BIB inner container is mainly heat-sealable polyethylene, especially soft polyethylene, since it always has a heat-sealing portion, but it is foldable, which is a characteristic of BIB,
Due to the fact that the content is a liquid, etc., physical strength, as mentioned above, especially transport vibration strength and pin pole resistance are required. Therefore, in combination with good stress crack resistance, ethylene- A vinyl acetate copolymer resin is more preferably used. Further, in the case where gas barrier properties such as oxygen are required due to the sophistication of the required performance, the inner container combining nylon film, saran coat / nylon film, aluminum vapor deposition nylon film, aluminum vapor deposition polyester film, etc. Is being put to practical use. An ethylene-vinyl alcohol copolymer (hereinafter referred to as EVOH), polyvinylidene chloride, aluminum foil or the like is used to impart a high gas barrier property.

However, although they have excellent gas barrier properties, they generally have low mechanical strength and cannot withstand bending fatigue. Therefore, it is used by being laminated between a base material layer having excellent mechanical strength and a heat-sealable material. However, when it is used as a constituent material of a BIB inner container, for example, pin poles, cracks or the like are generated in the constituent material. Or
Even at a stage where no pin pole is formed in the constituent material, the barrier property is deteriorated due to cracks or pinholes generated in the barrier layer used as the intermediate layer, so that it is excellent against severe bending fatigue. The gas barrier property cannot be maintained, and no practically satisfactory one has been found. The behavior of a laminated packaging material having a layer mainly composed of polyvinylidene chloride resin, an aluminum foil, a vapor-deposited resin layer of metal or the like as a barrier layer is described in, for example, JP-A-55-74.
No. 77 publication.

That is, the gas barrier property of the packaged product which is actually used and transported and handled is not necessarily satisfactory, and the most practically useful storage property after secondary distribution is often required. Betrayal results from damage to the barrier layer located in the intermediate layer. EVOH resin is the most excellent material for the intermediate layer provided to improve gas barrier properties, and is preferably used as a barrier material for various multilayer films and containers having a multilayer structure. This is because this resin not only has outstanding gas barrier properties, but also has excellent transparency, oil resistance, printability, moldability, etc., and does not impair the characteristics of the base resin. Because it has.

However, in the field where the pinhole resistance is particularly required, there is no example in which the EVOH resin is satisfactorily used as the barrier layer of the laminated packaging material. Above all, EVOH resin has been found to be used in an inner container of BIB having a gas barrier property against oxygen and the like, which is strongly required to endure flexural fatigue due to transport vibration as described above, and has been found to satisfy the requirement. However, the development of BIB having excellent barrier properties and flexural fatigue strength to withstand transport vibration was one of the important issues.

Further, in JP-A-61-220839, an intermediate layer prepared by blending EVOH with an ethylene-carboxylic acid vinyl ester copolymer or an ethylene-acrylic acid ester copolymer and a hydrotalcite-based compound,
A laminated packaging material having surface layers on both sides of the intermediate layer, at least one of which is a thermoplastic resin layer and each of which is arranged with an adhesive resin layer between them, is described, but the pinhole resistance is not always sufficient. However, it often caused product loss.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide a BIB which is free from the above-mentioned problems and is excellent in pin pole resistance and gas barrier property. It has an extremely excellent effect in preventing the occurrence of pinholes caused by bending and vibration during carrying, which can minimize product loss.

[0009]

[Means for Solving the Problems]
A composition containing (a) and a polyolefin (b) having at least one functional group selected from a boronic acid group, a borinic acid group, and a boronic acid group, a boron-containing group that can be converted into a boric acid group in the presence of water. This is achieved by providing a BIB, particularly a BIB inner container, having at least one layer or a resin composition layer in which the above-mentioned composition is blended with a thermoplastic resin (c).

In the present invention, EVOH is ethylene-
It is a saponified product of vinyl ester copolymer, and the ethylene content is preferably 20 to 80 mol%, more preferably 22 to 7
0 mol% and the saponification degree of the vinyl ester component is 8
It is preferably 0% or more, and more preferably 85% or more. When the ethylene content is less than 20 mol%, the melt moldability is poor, and the gas barrier property and heat stability are poor. In the present invention, EVOH may be more preferably blended with one or more kinds of EVOH having different ethylene contents and / or saponification degrees. A typical vinyl ester is vinyl acetate,
Other fatty acid vinyl esters (vinyl propionate,
Vinyl bivalate etc.) can also be used.

When the EVOH contains 0.0002 to 0.2 mol% of a vinylsilane compound as a copolymerization component, the consistency of the melt viscosity between the substrate and the EVOH is improved, and a homogeneous coextruded multilayer film is obtained. Is not only possible, but also when the EVOHs are blended with each other, the dispersibility is improved, which is effective in improving the moldability. Here, as the vinylsilane-based compound, for example, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltri (β
-Methoxy-ethoxy) silane and γ-methacryloxypropylmethoxysilane. Of these, vinyltrimethoxysilane and vinyltriethoxysilane are preferably used. Further, other comonomer [eg, propylene, butylene, unsaturated carboxylic acid or its ester {(meth) acrylic acid, (meth) acrylic acid ester methyl, ethyl) is used as long as the object of the present invention is not impaired.
}, Vinylpyrrolidone (N-vinylpyrrolidone, etc.) can also be used. Further, E used in the present invention
Suitable VOH Melt Index (MI) (190
Values measured at 2 ° C under a load of 2160 g; those whose melting point is near or above 190 ° C are under a load of 2160 g.
Measured at a plurality of temperatures equal to or higher than the melting point, the reciprocal of absolute temperature was plotted on the horizontal axis and the melt index (logarithm) was plotted on the vertical axis in a semilogarithmic graph, and the value extrapolated to 190 ° C.) was 0.1 to
50 g / 10 min. Optimally 0.5-20g / 10
Minutes.

Further, other additives (such as a plasticizer, a heat stabilizer, an anti-UV agent, an antioxidant, a colorant, a filler, and other resins) may be used in EVOH within a range not impairing the object of the present invention. Is free. In particular, as a measure for preventing gel formation, one or more of hydrotalcite-based compounds, hindered phenol-based, hindered amine-based heat stabilizers, and metal salts of higher fatty acid carboxylic acids (for example, calcium stearate, magnesium stearate, etc.) are used. It is preferable to add 0.01 to 1% by weight.

A polyolefin (b) having at least one functional group selected from the group consisting of a boronic acid group, a borinic acid group and a boronic acid group or a boron-containing group which can be converted into a boric acid group in the presence of water, which is used in the present invention; Is a boronic acid group, a borinic acid group, or at least one functional group selected from the group consisting of a boronic acid group and a boron-containing group which can be converted into a boric acid group in the presence of water, by means of a boron-carbon bond on the main chain or side chain. It is a polyolefin bound to a chain or end.
Of these, polyolefins in which the functional group is bonded to the side chain or the terminal are preferable, and polyolefins bonded to the terminal are most suitable. Here, the term "end" means one end or both ends. In addition, the carbon of the boron-carbon bond is derived from the base polymer of the polyolefin described later or from the boron compound reacted with the base polymer. A preferable example of the boron-carbon bond is a bond between boron and a main chain or an alkylene group at a terminal or side chain. Since a polyolefin having a boronic acid group is preferable in the present invention, this point will be described below. In the present invention, the boronic acid group is represented by the following formula (I).

[0014]

Embedded image

Further, the boron-containing group which can be converted into a boronic acid group in the presence of water (hereinafter simply referred to as a boron-containing group) is hydrolyzed in the presence of water and is represented by the above formula (I). If it is a boron-containing group that can be converted to a boronic acid group,
As a typical example, a boron ester group represented by the following general formula (II), a general formula (II
Examples thereof include a boronic acid anhydride group represented by I) and a boronic acid group represented by the following general formula (IV).

[0016]

Embedded image

[0017]

[Chemical 3]

[0018]

[Chemical 4]

[In the formula, X and Y are hydrogen atoms, aliphatic hydrocarbon groups (such as linear or branched alkyl groups having 1 to 20 carbon atoms, or alkenyl groups), alicyclic hydrocarbon groups (cyclo Alkyl group, cycloalkenyl group, etc.), aromatic hydrocarbon group (phenyl group, biphenyl group, etc.),
X and Y may be the same group or different. Further, X and Y may be bonded. However, it is excluded when both X and Y are hydrogen atoms. Further, R ¹ , R ² and R ³ are hydrogen atoms, aliphatic hydrocarbon groups, alicyclic hydrocarbon groups and aromatic hydrocarbon groups in which X and Y are the same, and R ¹ , R ² and R ^{3 are the same.}
May be the same group or different. M represents an alkali metal or an alkaline earth metal. Further, the above X, Y, R ¹ , R ² and R ³ may have other groups such as a carboxyl group and a halogen atom.

Specific examples of the boronic acid ester group represented by the general formulas (II) to (IV) include a boronic acid dimethyl ester group, a boronic acid diethyl ester group, a boronic acid dipropyl ester group, a boronic acid diisopropyl ester group, and boron. Acid dibutyl ester group, boronic acid dihexyl ester group, boronic acid dicyclohexyl group, boronic acid ethylene glycol ester group, boronic acid propylene glycol ester group (boronic acid 1,2-propanediol ester group, boronic acid 1,3-propanediol ester Group),
Boronic acid ester groups such as trimethylene glycol ester boronic acid group, neopentyl glycol ester boronic acid group, catechol ester boronic acid group, glycerin ester boronic acid group, trimethylolethane ester boronic acid group; boronic acid anhydride group; boronic acid group And alkaline earth metal bases of boronic acid.
Among the above-mentioned functional groups, especially a boronic acid ester group such as a boronic acid ethylene glycol ester group is EVOH.
It is preferable in terms of compatibility with (a). The boron-containing group that can be converted into a boronic acid group or a borinic acid group in the presence of water is the polyolefin (b) in water or a mixed liquid of water and an organic solvent (toluene, xylene, acetone, etc.). The reaction time is 10 minutes to 2 hours, and the reaction temperature is room temperature to 1
It means a group which can be converted into a boronic acid group or a borinic acid group when hydrolyzed under the condition of 50 ° C.

The content of the functional group is not particularly limited,
0.0001 to 1 meq / g (milliequivalent / g) is preferable, and 0.001 to 0.1 meq / g is particularly preferable.
It is surprising that the compatibility, transparency, etc. of the resin composition are significantly improved by the presence of such a small amount of functional groups.

The base polymer of the polyolefin (b) having a boron-containing group is ethylene, propylene, 1-butene, isobutene, 3-methylpentene, 1
Examples include olefin-based monomers represented by α-olefins such as hexene and 1-octene.

The base polymer is used as a polymer composed of one, two or three or more of these monomers. Of these base polymers, especially ethylene-based polymers (ultra low density polyethylene, low density polyethylene,
Medium density polyethylene, high density polyethylene, linear low density polyethylene, ethylene-vinyl acetate copolymer, ethylene-acrylic acid ester copolymer, ethylene-acrylic acid copolymer metal salt (Na, K, Zn-based ionomer) ), Ethylene-propylene copolymer}.

The preferred melt index (MI) of the polyolefin used in the present invention (value measured at 210 ° C. under a load of 2160 g) is preferably 0.005 to 1000 g / 10 minutes, and 0.1 to 100 g / 10 minutes. More preferable.

Next, a typical method for producing an olefin polymer having a boronic acid group and a boron-containing group used in the present invention will be described. An olefin-based polymer having a boron-containing group that can be converted into a boronic acid group in the presence of a boronic acid group or water is a borane complex and a trialkyl borate which are added to an olefin-based polymer having a carbon-carbon double bond under a nitrogen atmosphere. After obtaining an olefin polymer having a boronic acid dialkyl ester group by reacting an ester,
Obtained by reacting water or alcohols. When an olefin polymer having a double bond at the terminal is used as a raw material in this production method, an olefin polymer having a boronic acid group at the terminal or a boron-containing group which can be converted into a boronic acid group by the presence of water is obtained. If an olefin polymer having a double bond in its side chain or main chain is used as a raw material, an olefin polymer having a boronic acid group in its side chain or a boron-containing group which can be converted into a boronic acid group in the presence of water. Can be obtained.

As a typical method for producing an olefin polymer having a double bond as a raw material, 1) a method utilizing a small amount of double bond at the terminal of an ordinary olefin polymer;
2) A process for thermally decomposing an ordinary olefin-based polymer under anoxic conditions to obtain an olefin-based polymer having a double bond at a terminal; 3) Olefin by copolymerization of an olefin-based monomer and a diene-based polymer A method for obtaining a copolymer of a base monomer and a diene monomer. Regarding 1), a known olefin polymer production method can be used,
In particular, a production method using a metallocene-based polymerization catalyst as a polymerization catalyst without using hydrogen as a chain transfer agent (for example, DE40
30399) is preferred. Regarding 2), it can be obtained by a known method (for example, US 2835659, 3087922) by thermally decomposing an olefin-based polymer at a temperature of 300 ° C. to 500 ° C. under anoxic conditions such as a nitrogen atmosphere and a vacuum condition. . Regarding 3), a method for producing an olefin-diene polymer using a known Ziegler catalyst (see, for example, JP-A-50-44281, DE302127).
3) can be used.

As the borane complex, borane-tetrahydrofuran complex, borane-dimethylsulfide complex, borane-pyridine complex, borane-trimethylamine complex, borane-triethylamine and the like are preferable. Among these, borane-triethylamine complex and borane-trimethylamine complex are more preferable. The amount of the borane complex charged is preferably in the range of 1/3 equivalent to 10 equivalents with respect to the double bond of the olefin polymer. As the boric acid trialkyl ester, boric acid lower alkyl ester such as trimethyl borate, triethyl borate, tripropyl borate, and tributyl borate is preferable. The amount of the trialkyl borate ester charged is preferably in the range of 1 to 100 equivalents with respect to the double bond of the olefin polymer. The solvent is not particularly required to be used, but when it is used, a saturated hydrocarbon solvent such as hexane, heptane, octane, decane, dodecane, cyclohexane, ethylcyclohexane, decalin is preferable.

The reaction for introducing the boronic acid dialkyl ester group into the olefin polymer having a double bond is carried out at a reaction temperature of room temperature to 300 ° C., preferably 100 to 250 ° C., and a reaction time of 1 minute to 10 hours, preferably 5 minutes. ~ 5 hours is recommended.

The conditions for reacting water or alcohols are usually organic solvents such as toluene, xylene, acetone and ethyl acetate as reaction solvents, and water or alcohols such as methanol, ethanol and butanol; ethylene glycol, 1, 2-propanediol, 1.3
-Propanediol, neopenterglycol, glycerin, trimethylolethane, pentaerythritol,
Using a polyhydric alcohol such as dipentaerythritol in a large excess of 1 to 100 equivalents or more with respect to the boronic acid group,
It can be obtained by carrying out the reaction at a temperature of room temperature to 150 ° C. for about 1 minute to 1 day. The boron-containing group that can be converted to a boronic acid group among the functional groups is a reaction time of 10 minutes to 2 hours in water or a mixed solvent of water and an organic solvent (toluene, xylene, acetone, etc.). , Reaction temperature room temperature to 150
It means a group which can be converted into a boronic acid group when hydrolyzed under conditions of ° C.

Polyolefin is suitable as the thermoplastic resin composition (c) used in the present invention, and as the polyolefin, high density or low density polyethylene, polypropylene, polybutene-1, etc. and ethylene, propylene, butene-1, hexene can be used. It is a copolymer of α-olefins selected from -1, etc., but as a copolymer component with these α-olefins, diolefin, N-
Vinyl compounds such as vinylcarbazole, vinyl chloride, vinylidene chloride, vinyl acetate, styrene, acrylonitrile and vinyl ether; unsaturated carboxylic acids such as maleic acid, acrylic acid, methacrylic acid, ethacrylic acid, fumaric acid, itaconic acid Including those containing an acid component, an ester having a hydroxy or epoxy substituent, and an acid anhydride, for example, a copolymer of a graftable monomer and a polyolefin or an α-olefin / α, β-unsaturated carboxylic acid It is also possible to use a copolymer containing 50% by weight or more of α-olefin such as an ionomer resin which is a reaction product of the copolymer and the ionic metal compound. In addition, the polyolefin resin-based resin layer is added in order to improve the adhesion between the polyolefin resin alone or a mixture of two or more polyolefin resins and the polyolefin resin layer and other thermoplastic resin. A thermoplastic resin other than the polyolefin-based resin described above is also included in a small amount, that is, about 20% by weight or less.

Further, these resin compositions (a), (b),
Other additives may be added to the component (c), if necessary. Examples of such additives include antioxidants, ultraviolet absorbers, plasticizers, antistatic agents, lubricants, colorants, fillers, thermal stability improvers, or other polymeric compounds. These can be blended as long as the effects of the present invention are not impaired. The following are specific examples of the additive.

Antioxidants: 2,5-di-t-butylhydroquinone, 2,6-di-t-butyl-p-cresol, 4,4'-thiobis- (6-t-butylphenol), 2,2 ′ -Methylene-bis- (4-methyl-6-
t-butylphenol), octadecyl-3- (3,3
5'-di-t-butyl-4'-hydroxyphenyl) propionate, 4,4'-thiobis (6-t-butylphenol) and the like. UV absorber: ethylene-2-cyano-3,3'-diphenyl acrylate, 2- (2'-hydroxy-5'-
Methylphenyl) benzotriazole, 2- (2'-hydroxy-3'-t-butyl-5'-methylphenyl)
5-chlorobenzotriazole, 2-hydroxy-4-
Methoxybenzophenone, 2,2'-dihydroxy-4
-Methoxybenzophenone, 2-hydroxy-4-octoxybenzophenone and the like. Plasticizer: dimethyl phthalate, diethyl phthalate, dioctyl phthalate, wax, liquid paraffin, phosphate ester, etc. Antistatic agent: pentaerythritol monostearate, sorbitan monopalmitate, sulfated polyolefins,
Polyethylene oxide, carbowax, etc. Lubricants: ethylene bis stearamide, butyl stearate, etc. Coloring agent: carbon black, phthalocyanine, quinacridone, indoline, azo pigment, red iron oxide, etc. Filler: glass fiber, asbestos, ballastonite, calcium silicate, etc. Also, many other polymer compounds can be blended to the extent that the effects of the present invention are not impaired.

The resin composition ratio in the present invention is 30 to 95% by weight of EVOH (a) in the two-component system and 5 to 70% by weight of polyolefin (b) having a boron-containing group,
EVOH (a) is preferably 50 to 80% by weight, and polyolefin (b) having a boron-containing group is 20 to 50% by weight. In the three-component system, EVOH (a) is 30 to 95% by weight, and the boron-containing group-containing polyolefin (b) 2 to
67% by weight, thermoplastic resin (c) is 3 to 68% by weight, preferably EVOH (a) is 50 to 80% by weight, polyolefin (b) having a boron-containing group is 15 to 45% by weight, thermoplastic resin ( c) 5-35% by weight.

The resin composition of the present invention can be used in any of the intermediate layer, the outermost layer and the innermost layer. The resin to be laminated with the resin composition of the present invention is not particularly limited,
Generally, a resin having good transparency is preferable, and examples thereof include low-density polyethylene, linear low-density polyethylene, polypropylene, ethylene-propylene copolymer, polyolefin such as polybutene, ethylene-vinyl acetate copolymer, ethylene-acrylic acid. Examples thereof include ester copolymers, olefin-based copolymers such as ionomers, polystyrene, polyamide, polyethylene terephthalate, polycarbonate, polyvinyl chloride, and the like, or a mixture thereof. Of these, particularly preferably used are low-density polyethylene, linear low-density polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, alone or in a mixture thereof.

If the interlayer adhesion between these resins and the resin composition of the present invention is not sufficient, it is preferable to provide an adhesive resin layer. The adhesive resin is not particularly limited as long as it does not cause delamination at a practical stage, and is not particularly limited, and an unsaturated carboxylic acid or an anhydride thereof is used as an olefin polymer (for example, low density polyethylene, linear low density Polyolefins such as polyethylene, polypropylene and polybutylene, copolymers of olefins and unsaturated monomers copolymerizable therewith (vinyl esters, unsaturated carboxylic acid esters, etc.), for example ethylene-vinyl acetate copolymers, ethylene- A modified olefin-based polymer having a carboxyl group, which is obtained by chemically bonding (for example, an addition reaction or a graft reaction) to an acrylic acid ethyl ester copolymer) can be mentioned. Specifically, one selected from 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 copolymer, and the like. Alternatively, a mixture of two or more kinds is preferable. In addition, EVOH,
For example, the resin composition of the present invention can be mixed within a range that does not impair the effects of the present invention.

The thickness constitution is not particularly limited, but the thickness of the resin composition layer of the present invention is 5 to 5 from the viewpoint of pinhole resistance.
It is about 35 μ, and preferably 15 to 25 μ. The layer structure may be a resin composition single layer, a resin composition layer / thermoplastic resin layer, a thermoplastic resin layer / resin composition layer / thermoplastic resin layer,
Resin composition layer / thermoplastic resin layer / resin composition layer, thermoplastic resin layer / resin composition layer / thermoplastic resin layer / resin composition layer, thermoplastic resin layer / resin composition layer / thermoplastic resin layer /
A resin composition layer / thermoplastic resin layer and the like are conceivable, and those in which the above-mentioned adhesive resin is interposed between at least one of these layers can be mentioned. With such a multilayer structure, pinhole resistance, moisture resistance, and mechanical properties can be further improved.

[0037]

EXAMPLES Next, the present invention will be described in more detail with reference to synthesis examples, examples and comparative examples, but the present invention is not limited to these examples.

Synthesis Example Synthesis of Ultra Low Density Polyethylene Having Boronic Acid Ethylene Glycol Ester Group at the End: Ultra low density polyethylene {MI 7 g / 10 min (210 ° C., load 2160 g in a separable flask equipped with a condenser, stirrer and dropping funnel. ) Density 0.89, amount of terminal double bonds 0.048 meq / g} 1
After degassing by charging 000 g and decalin 2500 g and reducing the pressure at room temperature, nitrogen substitution was performed. To this, 78 g of trimethyl borate and 5.8 g of borane-triethylamine complex were added, and after reacting at 200 ° C. for 4 hours, a distillation tool was attached and 100 ml of methanol was slowly added dropwise. After completion of methanol dropping, by vacuum distillation,
Low boiling point impurities such as methanol, trimethyl borate, and triethylamine were distilled off. Further, 31 g of ethylene glycol was added, the mixture was stirred for 10 minutes, and then reprecipitated in acetone,
By drying, a boronic acid ethylene glycol ester group amount of 0.027 meq / g and MI 5 g / 10 min ultra low density polyethylene (B-PE) was obtained. Hereinafter, the present invention will be described in more detail with reference to Examples. (%) In Examples is based on weight unless otherwise specified.

Example 1 The ethylene content was 32 mol%, the degree of saponification of vinyl acetate component was 99.4 mol%, and the melt index (hereinafter referred to as MI) was 1.2 g / at 190 ° C. under a load of 2160 g.
EVOH 70% for 10 minutes and B-PE 30% obtained in the synthesis example
And were blended and pelletized at a temperature of 220 ° C. using a 30Φ different-direction twin-screw extruder. Further, using this pelletized resin composition, a film having a thickness of 25μ was formed by a film forming machine consisting of a 40Φ extruder and a T-die at an extruder temperature of 180 to 220 ° C. and a T-die temperature of 215 ° C. Got The film was evaluated for pinhole resistance. The pinhole resistance was measured using a Gelbo flex tester (manufactured by Rigaku Kogyo Co., Ltd.). The gelbo flex tester is a 12-inch x 8-inch sample piece with a diameter of 3.5.
In cylindrical shape, gripping both ends, initial gripping interval 7i
n, gripping interval at maximum bending is 1 in, the first 3.5 in of the stroke is twisted at an angle of 440 ° C, and then 2.5 in is a linear reciprocating motion of 40 times / min. It is carried out under the conditions of a speed of 20 ° C. and a relative humidity of 65%, and the pinhole resistance means the number of reciprocations until one pinhole is generated by the Gelbo flex tester.

Examples 2 to 7 Change of B-PE addition amount shown in Example 1 (10 to 30)
%), EVOH brand change and thermoplastic resin blended resin compositions were used to prepare 25 μm films in the same manner as in Example 1 and evaluated. The results are shown in Table 1. Example 2
All of Nos. 7 to 7 were excellent in pinhole resistance.

Comparative Example 1 In Example 1, a resin comprising 32 mol% of ethylene content, 99.4 mol% of saponification degree of vinyl acetate component, 70% of EVOH of MI 1.2 g / 10 min and 30% of B-PE obtained in the synthesis example. In place of the composition, a film of EVOH alone having a thickness of 25 μ was formed under the conditions of an extruder temperature of 180 to 220 ° C. and a T die temperature of 215 ° C. by using a film forming machine consisting of a 40Φ extruder and a T die as in Example 1. And evaluated variously. Table 2 shows the results
However, the pinhole resistance was poor.

Comparative Examples 2 to 4 Various thermoplastic resins 30% were used instead of B-PE obtained in the synthesis example.
Example 1 using a resin composition prepared by blending EVOH with
A film having a thickness of 25 μm was prepared and evaluated in the same manner as in.
Table 2 shows the results. The value of pinhole resistance was less than half that of the B-PE blend.

Example 8 EVOH 80 having an ethylene content of 32 mol%, a saponification degree of a vinyl acetate component of 99.4 mol% and an MI of 1.2 g / 10 min.
% And B-PE 20% shown in the synthesis example 15
μ of the resin composition layer, and a thickness of 3 each on both sides of the resin composition layer.
5 μm of 70% ethylene-vinyl acetate copolymer having a vinyl acetate content of 5% and 30% maleic anhydride-modified ethylene-vinyl acetate copolymer having a maleic anhydride content of 0.5%. The obtained laminated film was obtained by a coextrusion method using two extruders and a two-kind three-layer die head. As the resin composition used for the intermediate layer, pellets preliminarily blended by an extruder were used. The resulting laminated film was subjected to pinhole resistance until pinholes were recognized in the laminated film, and the amount of oxygen permeation at each stage until the occurrence of pinholes was measured. The results are shown in Table 3. There was almost no change in the amount of oxygen permeation until the occurrence of pinholes. Further, the occurrence of pinholes was not recognized after the number of flexing cycles of 9500 times, and it was confirmed that one pinhole was generated after 9600 times of bending. Moreover, delamination between the layers was not observed at all.

Comparative Example 5 In Example 8, B-PE was mixed with an ethylene content of 86 mol%,
The same procedure as in Example 8 was carried out except that the ethylene-vinyl acetate copolymer was changed to MI 2 g / 10 min. The results are shown in Table 4. There was almost no change in the amount of oxygen permeation until the occurrence of pinholes. Further, pinholes were not observed until the number of flexing was 7,000 times, and one was generated after 7,100 times. Further, delamination between the layers was not observed at all as in Example 8.

Example 9 Example 8 was repeated except that the thicknesses of the intermediate layer and the outer layer were changed. Table 5 shows the thickness of each layer and the results. As the resin composition layer (intermediate layer) is thinner and the thermoplastic resin layer (outer layer) is thicker, the number of times of bending increases.

[0046]

[Table 1]

[0047]

[Table 2]

[0048]

[Table 3]

[0049]

[Table 4]

[0050]

[Table 5]

[0051]

INDUSTRIAL APPLICABILITY As described above, the bag-in-box of the present invention has good gas barrier properties and excellent pinhole resistance. Therefore, it is possible to prevent pinholes generated by bending and vibration during transportation and carrying. Very few occurrences.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location C08L 29/04 LGT 43/00 LKA 101/00 LSZ

Claims (1)

[Claims] 1. An ethylene-vinyl alcohol copolymer (a) and at least one functional group selected from a boronic acid group, a borinic acid group, a boronic acid group and a boron-containing group which can be converted into a boric acid group in the presence of water. A bag-in-box having at least one composition layer containing a polyolefin (b) having a group or a resin composition layer obtained by blending the composition with a thermoplastic resin (c).