JPH115277A - Multilayer structure and multilayer container - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a multilayer structure excellent in sealing and unsealing performance by providing an innermost layer of EVOH having specified content of ethylene and an EVOH layer contiguous thereto satisfying a specified formula. SOLUTION: The multilayer structure comprises an innermost EVOH(C) layer containing 30-50 mol.% of ethylene and an EVOH(D) layer contiguous thereto satisfying formulas I-II [in the formula, CH(C), CH(D) represent ethylene content (mol.%) of the EVOH(C), (D), η(C), η(D) represent the viscosity (l/g) of phenol solution containing 15% of the EVOH(C), (D) at 30 deg.C, and L(C), L(D) represent the thickness (μ) of the EVOH(C), (D)]. Delamination takes place easily when the CH(C)-CH(D) is contained 50 mol.% or more and easy peeling performance can not be attained when, it is lower than 5 mol.%. Heat seal performance is insufficient when the η(D)-η(C) is 0.151 l/g or above and the easy peeling performance is deteriorated when it is lower than 0.01 l/g. Heat seal strength is not sufficient when the L(D)/L(C) is 99/1 and the easy peeling performance is not attained when it is 20/80.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to reducing or aggravating high quality flavors contained in foods and beverages, for example, citrus straight juices such as orange juice and lemon juice, or high quality aromas such as cosmetics and fragrances. Without, in a container of a multilayer configuration that can be packed and accommodated,
A container in which the lid material and the bottom material of the container can be easily heat-sealed and can be easily opened, and further, a high-quality, excellent-storability package composed of the container and various contents, particularly food. It relates to a package.

[0002]

2. Description of the Related Art In recent years, as containers for foods and the like, not only glass bottles and metal cans which have been conventionally used, but also containers made of a multilayer body of a thermoplastic resin and composite containers made of paper and a layer of a thermoplastic resin. Has come to be used. Accordingly, when the contents are foods, the deterioration of the flavor is a problem. In particular, in the case of citrus juice, or foods containing a large amount of the citrus juice, terpene hydrocarbons such as d-limonene constituting the flavor component are absorbed by polyolefin resins such as polyethylene used in the innermost layer of the container. Easy to be. If the flavor component of the food decreases or loses its balance during storage, it is inevitable that the flavor of the food deteriorates and the commercial value is lost. When an ethylene-vinyl alcohol copolymer (hereinafter referred to as EVOH) is used for the innermost layer in place of the polyolefin resin, as suggested in JP-A-63-3950, the absorption of the flavor component is extremely small, so Deterioration is relatively small and suitable.

[0003] By the way, a container always has a lid material and a bottom material, and it is necessary to seal both to make the inside of the container airtight.
The first technical problem is how to obtain a strong seal strength at a low temperature. The second important technical problem, which at first glance seems to contradict the first technical problem, is how easily the seal portion of the hermetic container can be opened. Therefore, the absorption of the above-mentioned flavor components is extremely low.
Using a lid material and a bottom material with VOH as the innermost layer, the EVOH was sealed in a manner that the EVOHs were in direct contact with each other to make an airtight container, and as a result, the sealing performance and the ease of opening were evaluated. As a result, the sealing temperature was too high. Outer layer substrate (polypropylene,
It has been found that there are many problems in practical use, such as deformation of polystyrene or the like, or too high sealing strength, or difficulty in opening.

[0004]

DISCLOSURE OF THE INVENTION The present invention does not have the above-mentioned problems, ie, flavor components of foods such as citrus juice, or high-quality fragrance components such as cosmetics and fragrances are not absorbed in a container, and Concerning the sealing between the lid and the bottom material to make the container airtight, a multilayer container having an EVOH layer in the innermost layer, which is excellent in sealability and openability, and further comprising the container and contents. It is intended to provide a package having high quality and excellent preservability.

[0005]

The above object is achieved by the following constitution. That is, the present invention relates to an EVOH (C) having an ethylene content of 30 to 85 mol%.
Is the innermost layer, has an EVOH (D) layer adjacent to the (C) layer, and satisfies the following formulas (IV) to (VI). 50 ≧ CH (C) −CH (D) ≧ 5 (IV) 0.15 ≧ η (D) −η (C) ≧ 0.01 (V) 99/1 ≧ L (D) / L (C) ≧ 20/80 (VI) where CH (C) and CH (D) are EVOH (C), E
Shows the ethylene content (mol%) of VOH (D). Η (C) and η (D) are EVOH (C), EVOH
The solution viscosity (l / g) of a 15% aqueous phenol solution at 30 ° C. of (D) is shown. Further, L (C) and L (D) indicate the thickness (μ) of EVOH (C) and EVOH (D).

The multilayer structure (Z) comprises the multilayer structure (Z) and a multilayer structure (W) having an EVOH (E) layer having an ethylene content of 20 to 85 mol% as an innermost layer. The multilayer container is configured such that the layer (C) and the layer (E) of the multilayer structure (W) are in direct contact with each other and are heat-sealed.

The inventors of the present invention used a three-type three-layer or four-type four-layer co-extrusion sheet film-forming apparatus to form a thermoplastic resin / adhesive resin (hereinafter referred to as Ad) / thick for a thermoforming cup having an EVOH structure. Sheets and thin sheets for lids were produced. The thick sheet is thermoformed so that the EVOH layer is located at the innermost layer to obtain a cup. After filling the cup with water, cover the cup so that the EVOH layer of the thin sheet for the lid is located at the innermost layer. The flange portion of the cup was heat-sealed with a temperature-controlled heat sealer. Then, the adhesive property and the easy peel property of the heat seal portion of this cup were evaluated. As a result, surprisingly,
It has been found that the use of EVOH satisfying the above formulas (IV) to (VI) not only enables low-temperature heat sealing, but also improves easy peelability.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS That is, according to the present invention, EVOH (C) having an ethylene content of 30 to 85 mol% is used as the innermost layer,
A multilayer structure (Z) having an EVOH (D) layer adjacent to the (C) layer and satisfying the following formulas (IV) to (VI). 50 ≧ CH (C) −CH (D) ≧ 5 (IV) 0.15 ≧ η (D) −η (C) ≧ 0.01 (V) 99/1 ≧ L (D) / L (C) ≧ 20/80 (VI) where CH (C) and CH (D) are EVOH (C), E
Shows the ethylene content (mol%) of VOH (D). Η (C) and η (D) are EVOH (C), EVOH
The solution viscosity (l / g) of a 15% aqueous phenol solution at 30 ° C. of (D) is shown. Further, L (C) and L (D) indicate the thickness (μ) of EVOH (C) and EVOH (D).

The multilayer structure (Z) comprises the multilayer structure (Z) and a multilayer structure (W) having an EVOH (E) layer having an ethylene content of 20 to 85 mol% as an innermost layer. The multilayer container is configured such that the layer (C) and the layer (E) of the multilayer structure (W) are in direct contact with each other and are heat-sealed.

When the content of CH (C) -CH (D) is 50 mol% or more, interlayer delamination is likely due to insufficient interlayer adhesion strength between the EVOH (C) layer and the EVOH (D) layer. On the other hand, when the content is 5 mol% or less, easy peelability is poor. Preferably, 48 ≧ CH (C) -CH (D) ≧ 10. Also,
When η (D) -η (C) is 0.15 l / g or more, the heat seal strength is not sufficient, and when η (D) -η (C) is 0.01 l / g or less, the easy peel property is poor. Preferably 0.12
≧ η (D) −η (C) ≧ 0.02. Further, as an important item, there is a thickness ratio between the EVOH (C) layer and the EVOH (D) layer. That is, L (D) / L (C)
Is 99/1 or more, the heat sealing strength is not sufficient. On the other hand, when the ratio is 20/80 or less, the layer (C) becomes too thick, and when the layer (C) is peeled from the layer (D), the layer (C) cannot be easily cut. Further, it is not preferable in terms of gas barrier properties. Preferably, 95/5 ≧ L (D) / L (C) ≧ 30/7
0. Generally, the values of CH (C) -CH (D) and η (D) -η (C) are large, and L (D) / L
A larger value of (C) is more preferable.

In this configuration, it is more preferable that the following expression is satisfied. 50 ≧ | CH (C) -CH (E) | ≧ 5 (VII) Preferably, 48 ≧ | CH (C) -CH (E) | ≧ 10 0.15 ≧ | η (E) -η (C) | ≧ 0.01 (VIII) Preferably, 0.12 ≧ | η (E) −η (C) | ≧ 0.02 {CH (C) −CH (E)} × {η (E) −η ( C)}> 0 (IX) where CH (E) represents the ethylene content of EVOH (E), and η (E) is the solution viscosity of EVOH (E) in a 15% aqueous phenol solution at 30 ° C. (l / g).

Here, | CH (C) -CH (E) |
When the amount is more than 5 mol%, the heat sealing strength is not sufficient. On the other hand, when the amount is less than 5 mol%, not only the heat sealing temperature is increased but also the easy peeling property is poor. More preferably 48
≧ | CH (C) −CH (E) | ≧ 10. Also, | η
When (E) -η (C) | is not less than 0.15 l / g, the heat seal strength is not sufficient, and when it is not more than 0.01 l / g, the easy peel property is poor. More preferred directions are | CH (C) -CH (E) | and | η
The larger the value of (E) −η (C) |, the higher the improvement effect. More preferably, 0.12 ≧ | η (E) −η (C) | ≧
0.02. Also, {CH (C) -CH (E)} × {η
When (E) −η (C)} becomes negative, the easy peeling property and the heat sealing property deteriorate.

In the present invention, EVOH (C) means an ethylene content of 30 to 85 mol%, preferably 40 to 70 mol%.
The EVOH (D) to be laminated thereon is selected in a range that satisfies the above formulas (IV) to (VI). Also E
VOH (E) has an ethylene content of 20 to 85 mol%
Any EVOH can be used, but the above (VII)
It is more effective to select a value within a range satisfying the expressions (IX) to (IX). If the ethylene content is less than the predetermined value, the melt moldability is poor, while if it exceeds the predetermined value, the gas barrier properties are insufficient. On the other hand, when the saponification degree is less than the predetermined value, the gas barrier property and the thermal stability deteriorate.

The EVOH may contain other comonomers [eg, propylene, butylene, unsaturated carboxylic acid or its ester {(meth) acrylic acid, (meth) acrylic ester) as long as the object of the present invention is not impaired. (Methyl, ethyl), etc.}, vinyl silane compounds (vinyl trimethoxy silane, vinyl triethoxy silane, etc.), vinyl pyrrolidone (N-vinyl pyrrolidone, etc.), plasticizers, heat stabilizers, ultraviolet rays Absorbent,
It is also free to blend an antioxidant, a colorant, a filler, and other resins (modified polyamide, modified polyester, partially saponified ethylene-vinyl acetate copolymer, vinylsilane compound-modified polyolefin, and the like). Above all, it is more preferable to blend the other resin with EVOH obtained by copolymerizing a vinylsilane compound and / or EVOH. Further, a preferable solution viscosity of the EVOH used in the present invention is 0.04 to 0.20 l / g, preferably 0.05 to 30 ° C. and 15% hydrous phenol.
０．１0.16 l / g.

In the present invention, the layer laminated on the EVOH layer of the multilayer structures (Z) and (W) includes a thermoplastic resin layer and / or a paper layer, but is not particularly limited. Polyethylene, polypropylene, ethylene propylene copolymer, ethylene vinyl acetate copolymer, ionomer, thermoplastic polyester, polyamide, polystyrene, polycarbonate, polyvinyl chloride, paper, at least one selected from aluminum or the like, or more is there.

In the present invention, the adhesive resin used to form a multilayer of EVOH and the thermoplastic resin, paper or aluminum (hereinafter, referred to as a substrate) includes:
The unsaturated carboxylic acid or its anhydride (such as maleic anhydride) is not particularly limited as long as it strongly adheres the EVOH layer and the base material layer to an olefin-based polymer or copolymer. [Polyethylene {low density polyethylene (LDPE), linear low density polyethylene (LLD)
PE), ultra-low density polyethylene (SLDPE), ethylene-vinyl acetate copolymer, ethylene- (meth) acrylate (methyl ester or ethyl ester)
Copolymer] is preferably used.

The EVOH used in the present invention can be molded into any molded product such as a film, a sheet, and a bottle by a well-known melt molding method and compression molding method. Remarkable features are exhibited when used as a layer of the body, and this will be described below. First, as a method of obtaining a multilayer structure,
The EVOH and the thermoplastic resin are often extruded through an adhesive resin by an extrusion lamination method, a dry lamination method, a coextrusion lamination method, a coextrusion sheet molding method, a coextrusion pipe molding method, a coinjection molding method, a solution coating method, or the like. Obtain a laminate, in some cases, the laminate is vacuum-pressure deep-drawn,
It is subjected to secondary molding such as biaxial stretching blow molding, biaxial stretching, and heating and stretching.

Although there is no particular limitation on the thickness constitution of the multilayer structure, the thickness ratio of the EVOH layer to the total thickness is 0.1 in consideration of moldability and cost.
About 2 to 50% is preferable. Further, the configuration of the multi-layer structure is as follows: EVOH layer / adhesive resin layer / thermoplastic resin layer, EVOH layer / thermoplastic resin layer, EVOH layer / adhesive resin layer / thermoplastic resin layer / adhesive resin layer / EVOH layer/
Adhesive resin layer / thermoplastic resin layer, EVOH layer / adhesive resin layer / adhesive resin layer / EVOH layer / adhesive resin layer / thermoplastic resin layer, EVOH layer / adhesive resin layer / paper or aluminum, EVOH layer / Paper or aluminum, E
VOH layer / adhesive resin layer / thermoplastic resin layer / adhesive resin layer / paper or aluminum, EVOH layer / adhesive resin layer / thermoplastic resin layer / paper or aluminum, EVO
H layer / adhesive resin layer / thermoplastic resin layer / paper or aluminum / thermoplastic resin layer are typical examples. When a thermoplastic resin layer is provided in multiple layers in a multilayer structure, these resins may be different or may be the same. Also, the EVOH layer is EVOH
In the case of a multi-layer of the (C) layer (the innermost layer) and the EVOH (D) layer, an adhesive resin layer is not usually provided between the (C) layer and the (D) layer, as long as the easy peel property is not impaired. If provided, it is free to provide an adhesive resin layer.

In the present invention, a container constructed so that the innermost layers of a multilayer structure having an EVOH layer as the innermost layer are in direct contact with each other and are heat-sealed includes a bottom material such as a cup and a bottle and a lid material. Thus, there can be mentioned a container in which both can be heat-sealed, a container in which the innermost layers of a film having an EVOH layer in the innermost layer are heat-sealed to each other, and the like.

As a method of heat sealing, for example, the same or different multilayer structure is used as an upper lid at the end or flange of the multilayer structure, and the innermost layer of EVOH is used.
There is a method in which the layers are arranged so as to be in contact with each other and heat sealed with a hot plate sealer, an impulse sealer, an ultrasonic sealer, a friction heat sealer, a dielectric heating sealer, or the like. At this time, corona treatment, flame treatment, application of an anchor coat agent, or application of water on one or both surfaces of the EVOH layer to be sealed is effective in increasing the sealing strength or lowering the sealing temperature, and is therefore preferable. In particular, a liquid bite seal is particularly suitable for applying water or filling with a water-containing system. On the other hand, EVO
The higher the water content of the H layer is, the more effective it is to reduce the sealing temperature due to the softening and melting of the EVOH, but sometimes whitening and foaming occur at the sealing portion, which may be undesirable in appearance. Therefore, the water content of the EVOH layer is 5% by weight or less, preferably 1% by weight.
It is as follows.

The opening property of the heat seal portion, that is, the easy peel property, is greatly improved by using the EVOH multilayer structure of the present invention. However, in order to further increase the easy peel property, the heat seal portion is required. Alternatively, there may be a case where a method of making a cut or drilling an anhydrous micro hole at a depth that does not penetrate the EVOH layer into and / or near the EVOH layer is effective.

The multilayer container of the present invention thus obtained has an extremely good gas barrier property and is effective for containers requiring fragrance retention properties. Foods such as orange juice, lemon juice, plum juice, grape juice,
Fruit juice beverages including processed fruit beverages such as strawberry juice or nectar; tomato juice, various vegetable juices; sugars such as sugar or fructose, citric acid, coloring agents, flavors, etc., or vitamins added as necessary Synthetic beverages containing the combined juice; lactic acid bacteria beverages; stews such as cooked curry and beef stew; soups such as consommé soup, potage soup, miso soup; preferred foods such as zenzai, yuzuki, juice powder, anmitsu, honey bean, jelly ;
Fishery or livestock products such as bacon, kamaboko, hamburger, sausage, and ham; fruit products such as tangerine, pineapple, cherry; seasonings such as soy sauce, sauce, vinegar, dressing, ketchup, mayonnaise, edible oil, and miso; margarine Favorite items such as butter and jam;
It is effective as a container for storing various contents such as beer, liquor, whiskey, grape wine, and spirit drinks including various cocktails such as ginfizu. Furthermore, it is also suitably used as a container for storing various contents such as liquid medicines such as Ringer's solution, agricultural chemicals, cosmetics, fragrances, detergents and the like as things other than the above drinking water and foods. Among them, citrus juice or a refreshing water containing a large amount thereof is preferably used. A package obtained by filling this container with the above-mentioned contents such as food, especially liquid food, cosmetics, and fragrance, and heat-sealing it is extremely effective because it has high quality and high storage stability.

[0023]

The present invention will be further described with reference to the following examples, but it should not be construed that the invention is limited thereto.

Example 1 EVOH (D) having an ethylene content of 32 mol%, a saponification degree of 99.4% and a solution viscosity η (value at 30 ° C., 15% hydrous phenol) of 0.11 l / g was used. ) (Eval manufactured by Kuraray Co., Ltd.), as EVOH (C), ethylene content 60 mol%, saponification degree 99.4%, solution viscosity η
(C) 0.07 l / g of EVOH (Eval manufactured by Kuraray), polystyrene (Idemitsu Styrol ET-61, hereinafter referred to as PS) as a base material, and maleic anhydride-modified ethylene- as an adhesive resin (hereinafter, referred to as Ad).
A multi-layer sheet was prepared by using a four-type four-layer coextrusion apparatus using a vinyl acetate resin. The outermost layer PS of the sheet is 800
μ, the Ad layer was 50 μm, the EVOH (D) was 45 μm, and the innermost layer EVOH (C) was 5 μm. Then, the sheet was applied to a vacuum pressure pneumatic molding machine at 180 ° C. so that the EVOH layer was on the inside to obtain a cup-shaped container having a drawing ratio of 0.5.

As the lid material, ethylene content is 60 mol%, saponification degree is 99.4%, solution viscosity η (C) is 0.07%.
1 / g EVOH (C) (Eval manufactured by Kuraray), ethylene content 32 mol%, saponification degree 99.4%, η (D)
0.11 l / g of EVOH (D) (Eval manufactured by Kuraray Co., Ltd.), polypropylene (Mitsubishi Petrochemical Nobrene MA-6, hereinafter referred to as PP) as a base material, and maleic anhydride-modified polypropylene as Ad (4 types and 4 layers) The extruder was used to produce a multilayer sheet. The outermost layer PP is 160 μm, the Ad layer is 20 μm, and EVOH
(D) 17 μ and the innermost layer EVOH (C) 3 μ were obtained.

The cup was filled with water, the upper lid was covered so that the EVOH layers were in contact with each other, and the cup flange was sealed with a hot plate at 120 ° C. under a liquid biting condition. The adhesive strength of the seal portion was as strong as 1100 g / 10 mm, and the container had a very good easy peel property and a high barrier property.

Example 2 As EVOH (E), EVO having an ethylene content of 32 mol%, a saponification degree of 99.4%, and a solution viscosity of η 0.11 l / g was used.
H (E) (Kuraray EVAL) and PS as base material
(Idemitsu Styrol ET-61) and maleic anhydride-modified ethylene-vinyl acetate resin as Ad
The resultant was subjected to a layer co-extrusion apparatus to produce a multilayer sheet. The sheet is configured such that the outermost layer PS is 800 μm, the Ad layer is 50 μm, and the innermost layer EVOH (E) is 50 μm. Then, the sheet was applied to a vacuum pressure pneumatic molding machine at 180 ° C. so that the EVOH layer was on the inside, and a cup-shaped container having a drawing ratio of 0.5 was obtained.

Water is poured into the cup, and the same lid material as used in Example 1 is put thereon so that the EVOH layers come into contact with each other.
The cup flange was sealed with a hot plate at 120 ° C. under the liquid biting condition. The adhesive strength of the seal portion was as strong as 1100 g / 10 mm, and the container had a very good easy peel property and a high barrier property.

Examples 3 and 4 Except for the conditions shown in Tables 1 and 2, the same conditions as in Example 2 were used. Table 2 shows the results.

Comparative Example 1 As a lid material, an ethylene content of 32 mol% and a saponification degree of 9 were used.
EVOH with 9.4%, solution viscosity η (D) 0.11 l / g
(D) (EVAL manufactured by Kuraray), PP (Mitsubishi Petrochemical Noblen MA-6) as base material, and adhesive resin A
A maleic anhydride-modified polypropylene was used as d, and a three-layer, three-layer coextrusion apparatus was used to prepare a multilayer sheet. The structure of the sheet is 160 μm for the outermost layer PP, 20 μm for the Ad layer, and 20 μm for the innermost layer EVOH (D).

Water was placed in the same cup as that obtained in Example 2, the above-mentioned upper lid material was covered so that the EVOH layers were in contact with each other, and the cup flange portion was sealed with a hot plate at 120 ° C. under a liquid biting condition. Peeling of the seal portion was impossible, and easy peelability was poor.

Comparative Examples 2 and 3 Except as shown in Tables 1 and 2, the same conditions as in Comparative Example 1 were used. Table 2 shows the results.

[0033]

[Table 1]

[0034]

[Table 2]

[0035]

According to the present invention, not only can heat sealing be performed at a low temperature, but also easy peeling at the time of opening is excellent, and furthermore, the flavor component of the content is reduced by long-term storage, and the content is reduced by oxidative deterioration. It is possible to obtain a multilayer container and a package that can significantly improve the deterioration of flavor.

Claims (4)

[Claims] An EV having an ethylene content of 30 to 85 mol%.
OH (C) as the innermost layer and the EVOH adjacent to the (C) layer
(D) A multilayer structure (Z) having a layer and satisfying the following formulas (IV) to (VI). 50 ≧ CH (C) −CH (D) ≧ 5 (IV) 0.15 ≧ η (D) −η (C) ≧ 0.01 (V) 99/1 ≧ L (D) / L (C) ≧ 20/80 (VI) where CH (C) and CH (D) are EVOH (C), E
Shows the ethylene content (mol%) of VOH (D). Η (C) and η (D) are EVOH (C), EVOH
The solution viscosity (l / g) of a 15% aqueous phenol solution at 30 ° C. of (D) is shown. Further, L (C) and L (D) indicate the thickness (μ) of EVOH (C) and EVOH (D). 2. A multilayer structure comprising the multilayer structure (Z) according to claim 1 and a multilayer structure (W) having an EVOH (E) layer having an ethylene content of 20 to 85 mol% as an innermost layer. A multilayer container configured so that the (C) layer of (Z) and the (E) layer of the multilayer structure (W) are in direct contact and are heat-sealed. 3. The multilayer container according to claim 2, which satisfies the following formulas (VII) to (IX). 50 ≧ | CH (C) -CH (E) | ≧ 5 (VII) 0.15 ≧ | η (E) −η (C) | ≧ 0.01 (VIII) ｛CH (C) -CH (E) ｝ × {η (E) −η (C)}> 0 (IX) where CH (C) and CH (E) are EVOH (C) and E
Shows the ethylene content (mol%) of VOH (E). Η (C) and η (E) are EVOH (C), EVOH
The solution viscosity (l / g) of (E) in a 15% aqueous phenol solution at 30 ° C. is shown. EVOH indicates an ethylene-vinyl alcohol copolymer. 4. A package obtained by filling the container according to claim 2 or 3 with contents and heat-sealing the container.