JPH10128883A - Bag-in-box container - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the development of pinholes due to flexure and vibration by a method wherein a formed body having at least one resin composition layer prepared by compounding a specified amount of a saponified ethylene-vinyl ester copolymer, the ethylene content and the degree of saponification of vinyl acetate component of which are specified, with a specified amount of a polyaminoamide, is produced. SOLUTION: By extruding and forming a gas barrier layer by an inflation system or a T-die system, a bag-in-box container is formed into a formed body having at least one gas barrier layer. A saponified ethylene-vinyl ester copolymer (henceforth expressed as EVOH) used in the gas barrier layer consists of 20-60mol.% of ethylene content, 98-70 pts.wt. of the saponified ethylene-vinyl ester copolymer, the degree of saponification of a vinyl-acetate ester component of which is 90mol.% or more, and 2-30 pts.wt. of a polyaminoamide(PAA). Further, the PAA is obtained by condensing a dicarboxylic acid and a polyamine.

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 inner container having excellent pinhole resistance and gas barrier properties.

[0002]

2. Description of the Related Art Recently, with the streamlining of distribution methods, bag-in-box (or bag-in-carton) (a bag-in-box is called a foldable plastic thin inner container and a stackable material) as one of flexible laminated packaging materials. Containers in combination with an outer cardboard box having portability and printability) are often used. The function required for the bag-in-box inner container is the preservability of the packaged material, that is, the prevention of deterioration, and for that purpose, particularly the transport vibration strength and the pinhole resistance are required. For the bag-in-box inner container, for example, a combination of a base film for maintaining mechanical strength and a heat-sealable material is generally used, and the material is selected according to the performance required of the packaged object. You. Above all, for applications where gas barrier properties such as oxygen are required for the substrate film, a method of laminating a heat-sealable material by providing a gas barrier layer on the substrate layer and using the barrier layer as an intermediate layer Has been adopted.

[0003] In order to impart high gas barrier properties, ethylene-vinyl alcohol copolymer (hereinafter referred to as EVOH), polyvinylidene chloride, aluminum foil and the like are used. However, although they are excellent in gas barrier properties,
The mechanical strength is generally low and is not particularly resistant to bending fatigue. Therefore, for example, when used as a component material of the bag-in-box inner container, the component material, pinhole,
Even at a stage where cracks or the like are generated or a pinhole is not generated in the constituent material, excellent gas barrier properties due to a decrease in barrier properties due to cracks and pinholes generated in the gas barrier layer used as the intermediate layer are exhibited. It cannot be retained and has not been found to be practically satisfactory.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a bag-in-box inner container having excellent pinhole resistance and gas barrier properties, particularly, bending during transportation and carrying.
An object of the present invention is to provide a bag-in-box inner container in which the generation of pinholes caused by vibration is extremely small, and thereby the loss of contents can be minimized.

[0005]

Means for Solving the Problems The present inventors have intensively studied to improve the pinhole resistance of EVOH resin. As a result, it has been found that, if a specific polyamide is blended in the EVOH resin, a resin composition having excellent pinhole resistance can be obtained without significantly impairing the high gas barrier properties of the EVOH, and the present invention has been completed. Reached. That is, the present invention comprises 98 to 70 parts by weight of a saponified ethylene vinyl ester copolymer having an ethylene content of 20 to 60 mol% and a saponification degree of the vinyl acetate component of 90 mol% or more and 2 to 30 parts by weight of polyaminoamide. The present invention provides a bag-in-box inner container formed by molding into a molded article having at least one resin composition layer (hereinafter sometimes referred to as a gas barrier layer).

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The gas barrier layer used in the present invention comprises:
For example, it is extruded and formed by an inflation method or a T-die method. The bag-in-box inner container of the present invention is formed by molding into a molded article having at least one gas barrier layer. When the molded article is composed of two or more layers, the gas barrier layer is formed on any of the layers. It can also be used. Examples of the layer structure of the molded article include an outer layer, a gas barrier layer, an inner layer, and an adhesive resin layer (glue layer, tie layer layer) for bonding these layers, and a regrind layer as necessary. Can also be included.

[0007] Polyaminoamide, one of the resins used in the gas barrier layer of the present invention, can be usually obtained by condensing a dicarboxylic acid and a polyamine.
As dicarboxylic acids, for example, malonic acid, succinic acid,
Glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, dodecandionic acid, tetradecandionic acid, hexadecandionic acid, octadecanedioic acid, octadecenedioic acid, eicosadioic acid, eicosendioic acid, docosandioic acid, 2,2,4-trimethyladipic acid or the like is industrially an aliphatic dicarboxylic acid such as a polymer of a natural fat or oil fatty acid such as soybean oil; an alicyclic dicarboxylic acid such as 1,4-cyclohexanedicarboxylic acid;
Examples thereof include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, phthalic acid, and xylene dicarboxylic acid, and preferred are aliphatic dicarboxylic acids, and particularly preferred are polymerization of adipic acid, azelaic acid, and natural fatty acids. Things.

Examples of the polyamine include diethylenetriamine, triethylenetetramine, tetraethylenepentamine, iminobispropylamine, spermine,
And polyalkylene polyamines such as spermidine and bis (hexamethylene) triamine. Preferably, diethylenetriamine, triethylenetetramine, tetraethylenepentamine and bis (hexamethylene) triamine are exemplified.

In addition, in the condensation polymerization of these dicarboxylic acids and polyamines, depending on viscosity adjustment and other purposes,
Monoamine and monocarboxylic acid can coexist. Such monoamines include, for example, methylamine,
Ethylamine, propylamine, butylamine, pentylamine, hexylamine, heptylamine, octylamine, 2-ethylhexylamine, nonylamine, decylamine, undecylamine, dodecylamine, tridecylamine, tetradecylamine, pentadecylamine, hexadecylamine Aliphatic monoamines such as octadecylamine, eicosylamine and docosylamine; alicyclic monoamines such as cyclohexylamine and methylcyclohexylamine; aliphatic monoamines substituted with an aromatic group such as benzylamine and β-phenylethylamine. Can be Further, as the monocarboxylic acid, for example, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid,
Enanthic acid, caprylic acid, capric acid, pelargonic acid,
Aliphatic acids such as undecanoic acid, lauric acid, tridecanoic acid, myristic acid, myretic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, arachinic acid, behenic acid, or industrially natural fatty acids such as soybean oil Examples include alicyclic monocarboxylic acids such as monocarboxylic acid, cyclohexanecarboxylic acid, and methylcyclohexanecarboxylic acid, and aromatic monocarboxylic acids such as benzoic acid, toluic acid, ethylbenzoic acid, and phenylacetic acid.

The saponified ethylene vinyl ester copolymer (EVOH) used in the present invention has an ethylene content of 20 to 60 mol%, preferably 20 to 45 mol, in view of melt moldability and gas barrier properties under high humidity. %, More preferably 25 to 40 mol%, and from the viewpoint of gas barrier properties, the degree of saponification of the vinyl ester component is 90 mol%.
Or more, preferably 95 mol% or more, more preferably 98 mol% or more.
Mol% or more.

The EVOH used in the present invention comprises one or more EVOs having different ethylene contents and different degrees of saponification.
In some cases, it is more preferable to use H as a blend.
A typical example of the vinyl ester component is vinyl acetate, and other fatty acid vinyl esters,
For example, vinyl propionate, vinyl pivalate and the like can be used. The weight ratio of polyaminoamide (hereinafter may be abbreviated as PAA) and saponified ethylene vinyl ester copolymer (EVOH) in the resin composition of the gas barrier layer used in the present invention depends on gas barrier properties and pinhole resistance. And PAA / EVOH is usually 2/98 to 30
/ 70.

The method for producing the gas barrier layer of the present invention, that is, the method for blending PAA and EVOH is not particularly limited, but the pellet is obtained by melt-kneading and extruding using a general single-screw or twin-screw extruder used for kneading. A method can be exemplified. PAA is often used as a liquid or dissolved in water or an organic solvent. In this case, the PAA liquid is pumped into the cylinder of the extruder under the hot melt extrusion of EVOH. Inject with EVOH
After blending the EVOH pellets and the PAA liquid with a mixer such as a Henschel mixer,
A method in which the mixture is supplied to the extruder and heat-kneaded can be adopted. Alternatively, a high-concentration master batch of PAA is separately prepared, and the master batch is pellet-blended with EVOH and directly supplied to a film or another molding machine to obtain a molded product.

[0013] In addition to these components, the resin composition used in the gas barrier layer of the present invention may contain additives such as a plasticizer, a heat stabilizer, an ultraviolet ray inhibitor, an antioxidant, a colorant, a filler, and other additives. Resins and the like can be used as long as the object of the present invention is not hindered. In particular, as a measure for preventing gel formation, one or more of a hydrotalcite-based compound, a hindered phenol-based, a hindered amine-based heat stabilizer, and a metal salt of a higher fatty acid carboxylic acid, such as calcium stearate and magnesium stearate, may be used as a resin. It is preferable to add, for example, 0.01 to 1% by weight to the composition.

The gas barrier layer used in the present invention can be used as a single layer, but usually, for example, an intermediate layer, an outer layer,
It can be used for any layer such as the inner layer. The resin of the resin layer laminated with the gas barrier layer used in the present invention is not particularly limited, but is generally preferably a resin having good transparency, for example, polyolefin resin, polystyrene, polyamide, polyethylene terephthalate, polycarbonate, poly Examples thereof include vinyl chloride and the like, and mixtures thereof. Of these, polyolefin resins are preferably used.

[0015] The polyolefin resin is not particularly limited. Examples thereof include low-density polyethylene, ionomers and precursors thereof, and linear ethylene / α-olefin copolymers (eg, LLDPE, VLDPE, ULDP).
E), an ethylene-vinyl acetate copolymer, an ethylene acrylate copolymer and the like. In addition, polyolefin obtained using a metallocene catalyst (single-site catalyst) can also be used as appropriate. Metallocene catalysts include, for example, titanium (Ti), zirconium (Z
r), nickel (Ni), palladium (Pd), hafnium (Hf), tetravalent transition metals such as platinum (Pt),
A compound in which one or more cyclopentadienyl rings or analogs thereof are present as ligands, named after the discoverer, Kaminsky.
Catalyst or Kaminsky-S
inn) Also called catalyst. In addition, since they have the same characteristic of active sites, they are also called a single-site catalyst or a homogeneous catalyst.

When the interlayer adhesion between the gas barrier layer and another layer 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.For example, the unsaturated carboxylic acid or its anhydride may be an olefin polymer (for example, low-density polyethylene, linear Low-density polyethylene, polypropylene, polyolefins such as polybutylene, copolymers of olefins and copolymerizable unsaturated monomers (vinyl esters, unsaturated carboxylic acid esters, etc.), for example, ethylene-vinyl acetate copolymers, Modified olefin polymers containing a carboxyl group obtained by chemically (eg, by addition reaction or graft reaction) bonding to an ethylene-acrylic acid ethyl ester copolymer). Specifically, for example, maleic anhydride graft-modified polyethylene,
One or a mixture of two or more selected from maleic anhydride graft-modified polypropylene, maleic anhydride graft-modified ethylene-ethyl acrylate copolymer, maleic anhydride graft-modified ethylene-vinyl acetate copolymer, and the like are preferable. No. In addition, EVOH, for example, the gas barrier layer of the present invention, can be mixed with these adhesive resins within a range that does not impair the effects of the present invention.

The thickness of the gas barrier layer used in the present invention is not particularly limited, but is usually about 5 to 35 μm, and preferably about 10 to 25 μm from the viewpoint of pinhole resistance. Although the layer constitution of the bag-in-box inner container of the present invention is not particularly limited, for example, a single layer of a gas barrier layer;
Gas barrier layer / thermoplastic resin layer; thermoplastic resin layer / gas barrier layer / thermoplastic resin layer, gas barrier layer / thermoplastic resin layer / gas barrier layer; thermoplastic resin layer / gas barrier layer /
Thermoplastic resin layer / gas barrier layer; thermoplastic resin layer / gas barrier layer / thermoplastic resin layer / gas barrier layer / thermoplastic resin layer, etc., and the above-mentioned adhesive resin is interposed between at least one of these layers. What was made is mentioned. With such a multilayer structure, the pinhole resistance, the moisture resistance, and the mechanical properties can be further improved.

[0018]

According to the bag-in-box inner container of the present invention,
Since it has excellent gas barrier properties and pinhole resistance, it is extremely excellent without impairing the quality of the contents and without any loss of the contents.

[0019]

The present invention will be described below in detail with reference to examples, but the present invention is not limited to these examples. (Example 1) Ethylene content: 44 mol%, saponification degree: 98
% Or more of EVOH (EP-E105B manufactured by Kuraray Co., Ltd.):
An abbreviated as EVOH-E) was used as a twin screw extruder (L / D60, 40 mmφ extruder BT-40-S2, manufactured by Plastic Engineering Co., Ltd.).
-60-L) and melt-kneaded with polyaminoamide (hereinafter PA)
A-1 (abbreviated as A-1) in a 50 wt% aqueous solution (Sumitomo Chemical Industries, Ltd., Sumireze Resin IM60) was injected into the extruder barrel by a liquid feed pump, and water was removed from a vent port installed in the middle barrel. While extruding at an extrusion temperature of 200 ° C. and an extrusion rate of 13 kg / hr, the mixture was pelletized. PAA-1
/ EVOH-E weight ratio = 10/90. This resin composition was used as a resin composition for forming a gas barrier layer.
Next, using a plurality of extruders, inflation molding was performed with the following layer configuration to obtain a molded body. (1) Layer configuration From the outer layer side: LLDPE / adhesive resin / gas barrier layer /
Adhesive resin / LLDPE (2) Thickness of each layer (μm) From the outer layer side: 50/5/10/5/50 (total 120μ)
m) (4) Resin used LLDPE: density = 0.9127 g / cm ³ , MFR =
1.0 (JIS K-6760) ethylene-butene-
1 Random copolymer Adhesive resin: Acid-modified polyethylene [Mitsui Petrochemical Co., Ltd.
Admer, density = 0.92 g / cm ³ , melting point = 110
° C] The pinhole resistance was measured using a gelbo flex tester (manufactured by Toyo Seiki Co., Ltd.). The sample size is A
It is 4 sizes, is made cylindrical so that its long axis is a circumference, grips both ends, and performs a reciprocating reciprocating motion of compressing while applying a twist of 440 ° C. at a speed of 40 times / min. This is performed under the conditions of 25 ° C. and 65% relative humidity.
The pinhole resistance was evaluated by counting the number of pinholes generated in the gas barrier layer of the sample as a result of 2,000 reciprocating motions with a magnifying glass. The smaller the number of pinholes, the higher the pinhole resistance. The number of pinholes of the molded article having the above configuration was 3, indicating good pinhole resistance.

(Example 2) Polyaminoamide (Tomide # 235-A manufactured by Fuji Kasei; hereinafter abbreviated as PAA-2) obtained by condensation polymerization of vegetable oil fatty acid polymer instead of adipic acid and triethylenetetramine instead of diethylenetriamine was used. The mixture was injected into an extruder barrel by a liquid feed pump, extruded and kneaded with EVOH-E at an extrusion temperature of 200 ° C. and an extrusion rate of 13 kg / hr, and pelletized. PAA-2 / EVOH-E
The weight ratio was 10/90. A molded article was produced in the same manner as in Example 1 except that this resin composition was used as a resin composition for a gas barrier layer. The number of pinholes after the gelbo flex test of the obtained molded article was 6, indicating excellent pinhole resistance. In addition, PAA-2 has a viscosity at 25 ° C. of 8000 to 18000 mPa · s, and JIS K7
The amine value measured according to 237 is 390 ± 15.

(Example 3) Polyaminoamide obtained by condensation polymerization of vegetable oil fatty acid polymer instead of adipic acid and triethylenetetramine instead of diethylenetriamine (Tomide # 427-A manufactured by Fuji Kasei; hereinafter abbreviated as PAA-3) was used. The mixture was injected into an extruder barrel by a liquid feed pump, extruded and kneaded with EVOH-E at an extrusion temperature of 200 ° C. and an extrusion rate of 13 kg / hr, and pelletized. PAA-3 / EVOH-E
The weight ratio was 10/90. A molded article was produced in the same manner as in Example 1 except that this resin composition was used as the resin composition for a gas barrier layer, and the obtained molded article had a pinhole number of 8 after the Gelboflex test, which was excellent. It showed pinhole resistance. In addition, PAA-3 has a viscosity at 40 ° C. of 75300 mPa · s and an amine value of 251 measured according to JIS K7237.

(Comparative Example 1) A molded article obtained in the same manner as in Example 1 except that extrusion kneading with a polyaminoamide was not performed, the number of pinholes after the Gelboflex test was 20, and the pinhole resistance was low. It was inferior in sex.

Claims (6)

[Claims] 1. A saponified ethylene vinyl ester copolymer having an ethylene content of 20 to 60 mol% and a saponification degree of at least 90 mol% of a vinyl acetate component and 98 to 70 parts by weight of a polyaminoamide. A bag-in-box inner container formed by molding into a molded article having at least one resin composition layer. 2. The bag-in-box inner container according to claim 1, wherein the polyaminoamide is obtained by condensing a dicarboxylic acid and a polyamine. 3. The bag-in-box inner container according to claim 2, wherein the polyamine is a polyalkylene polyamine. 4. The bag-in-box inner container according to claim 2, wherein the polyamine is diethylenetriamine, triethylenetetramine or tetraethylenepentamine. 5. The bag-in-box inner container according to claim 2, wherein the dicarboxylic acid is an aliphatic dicarboxylic acid. 6. The bag-in-box inner container according to claim 2, wherein the dicarboxylic acid is a polymer of azelaic acid or a natural fat or oil fatty acid.