JP2003118778A - Retort pouch - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a retort pouch with which oxygen in a container is removed to improve preservability of contents. SOLUTION: The retort pouch is formed of a laminate film comprising an external layer formed by dry-laminating at least one oxygen barrier layer and a cushion layer and an internal layer formed by co-extruding or sandwich- laminating an oxygen absorbing layer comprising an olefin-based resin containing 2 to 40% of a modified polyolefin resin and an oxygen absorbing agent blended into the resin, and a heat-sealing layer on one of the surfaces of the external layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pouch for retort which is excellent in preservability, flavor retention and retortability of contents for a long time.

[0002]

2. Description of the Related Art Conventionally, metal cans, glass bottles, various plastic containers, etc. have been used as containers. However, plastic containers are used for various purposes in terms of lightness, impact resistance, and cost. . However, in metal cans and glass bottles, oxygen permeation through the container wall is zero, whereas in the case of plastic containers, oxygen permeation through the container wall occurs in a non-negligible order, and in terms of storability of contents. It's a problem. In order to prevent this, in a plastic container, the container wall has a multi-layered structure, and at least one of them has a resin having oxygen permeation resistance such as an ethylene-vinyl alcohol copolymer. An oxygen absorbent has been used for a long time in order to remove oxygen in a container, and examples of applying this to a container wall include JP-B-62-1824 and JP-A-10-114371. According to the invention, a multilayer structure for packaging is obtained by laminating a layer obtained by blending a resin having oxygen permeability with an oxygen absorbent containing a reducing substance as a main component, and a layer having oxygen gas barrier property. It is a thing. However, although this publication discloses a container formed by vacuum forming or the like, there is no description of a retort pouch that has been widely used in recent years, and a metal or a metal compound is added to the inner surface material in an amount exhibiting an oxygen absorbing effect. Then, the foreign substance effect works, resulting in a decrease in strength such as impact resistance strength and heat seal strength. Particularly, in the case of two or more kinds of polymers, the seal strength and the drop strength are remarkably lowered due to the synergistic effect of the incompatibility effect. Even in the case of a single polymer, in the case of a block copolymer, it has a sea-island structure internally having a non-uniform structure, and the seal strength and the drop strength are remarkably lowered as in the case of two or more kinds of polymers. If the seal strength and impact strength decrease, it cannot be used for retorts.

[0003]

SUMMARY OF THE INVENTION The present invention provides a pouch for a retort, which removes oxygen in the container and improves the seal strength, impact resistance and retort resistance.

[0004]

Means for Solving the Problems The present invention provides "1. One surface of an outer surface layer formed by dry lamination of at least one oxygen barrier layer and a cushion layer,
A retort formed by a laminated film having an inner layer formed by coextrusion or sandwich lamination of an oxygen absorbing layer in which an oxygen absorbing agent is mixed with an olefin resin containing 2 to 40% of a modified polyolefin resin and a heat sealable layer. Pouch. 2. The pouch for a retort according to item 1, wherein the oxygen barrier layer is a plastic film having a coating made of an inorganic oxide. 3. The oxygen absorption layer contains 5 to 4 metal or metal compound powder.
The pouch for a retort according to item 1, which is a layer containing 0%. 4. Oxygen absorption layer is ethylene-propylene block copolymer, ethylene-propylene random copolymer, linear low density polyethylene, high density polyethylene, ethylene-
Item 1 which is a layer formed of a composition in which a metal or a metal compound powder is blended as an oxygen absorbent into a blended product obtained by blending one or more modified polyolefin resins selected from propylene rubber and ethylene-butene copolymer. A pouch for a retort according to any one of 1 to 3. 5. The pouch for retort according to any one of items 1 to 4, wherein the modified polyolefin resin is one or more resins selected from maleic acid modified polypropylene and maleic acid modified polyethylene. 6. The pouch for retort according to any one of items 1 to 5, wherein the cushion layer and the heat-sealing layer disposed on the innermost surface are layers having an ethylene-propylene block copolymer having a melting point of 115 ° C or higher. 7. The pouch for retort according to any one of items 1 to 6, wherein the heat sealable layer disposed on the innermost surface is a layer containing a white pigment such as titanium white. 8. The thickness of the oxygen absorbing layer is 10 μm to 40 μm,
The thickness of the heat-sealing layer disposed on the innermost surface is 10 μm ~
The retort pouch according to any one of items 1 to 7, which has a thickness of 50 μm. 9. The pouch for a retort according to any one of items 1 to 8, wherein an amount of the oxygen absorbent in the bottom material forming the pouch bottom is mixed with an amount of the oxygen absorbent in the body forming the pouch body. Standing pouch for retort that is smaller than the quantity. Regarding

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, an oxygen absorbing layer containing an oxygen absorbing agent is arranged on one side of an outer surface layer. This oxygen absorbing layer is a layer in which an oxygen absorbing agent is mixed with an olefin resin containing 2 to 40% by weight of a modified polyolefin resin. In this layer, the modified polyolefin resin present around the oxygen absorbent dispersed in the olefin resin improves the adhesion between the oxygen absorbent and the olefin resin, improves the transparency of the oxygen absorption layer, and further improves the outer surface layer and The effect of improving the adhesive strength with the heat seal layer is exhibited. In the present invention, the oxygen barrier layer and the cushion layer of the outer surface layer are formed by dry lamination, but the oxygen absorption layer and the heat seal layer provided on one surface of the outer layer are formed by coextrusion or sandwich lamination, and therefore the softening point of the modified polyolefin resin or the like. It is possible to use a resin having a high temperature, and the retort compatibility is very good.

As the modified polyolefin resin, an olefin resin modified with maleic acid, fumaric acid, itaconic acid or the like is used, and one or more resins selected from maleic acid modified polypropylene and maleic acid modified polyethylene are suitable. used. The modified polyolefin resin is blended in an amount of 2 to 40% by weight. If it is 2% by weight or less, the adhesive effect between the oxygen absorbent and the olefin resin is poor, and if it is 40% by weight or more, it becomes very brittle, which is not preferable.

Examples of the olefin resin used in the oxygen absorbing layer include ethylene-propylene block copolymer, ethylene-propylene random copolymer, linear low density polyethylene, high density polyethylene, ethylene-propylene rubber, ethylene-butene. 1 or 2 or more selected from copolymers.

Examples of the oxygen absorbent include metal powders having reducing properties such as reducing iron, reducing zinc, reducing tin powders; lower metal oxides such as ferrous oxide, ferric oxide and further reducing metals. Compounds, such as iron carbide, silicon iron, iron carbonyl, iron hydroxide; and the like, which contain one or a combination thereof as a main component, may be used, and if necessary, these may be hydroxides of alkali metals or alkaline earth metals. Compounds, carbonates, sulfites, thiosulfates, tertiary phosphates, secondary phosphates, organic acid salts, halides and the like. The compounding ratio is 5 to 40% by weight. If it is 5% by weight or less, the oxygen absorption effect is not sufficient, and if it is 40% by weight or more, it becomes very brittle, which is not preferable. The thickness of the oxygen absorption layer is 1
It is 0 to 40 μm, and if it is 10 μm or less, the oxygen absorption capacity becomes insufficient, and if it is 40 μm or more, it becomes brittle as a whole, which is not preferable.

As the oxygen barrier layer, a thermoplastic resin having a low oxygen permeability coefficient and capable of being matured is used. Examples of the gas barrier resin include ethylene-vinyl alcohol copolymers, for example, an ethylene content of 20 to 60 mol%, particularly 25 to 50 mol%.
The ethylene-vinyl acetate copolymer of which the saponification degree is 9
A saponified product of a copolymer obtained by saponification to be 6 mol% or more, particularly 99 mol% or more is used. The saponified product of the ethylene-vinyl alcohol copolymer should have a molecular weight sufficient to form a film, and generally has a molecular weight of 0.1% as measured at 30 ° C. in a mixed solvent of 85:15 by weight of phenol: water. 01dL / g or more, especially 0.05dL / g
It is desirable to have the above viscosity. Further, as another example of the gas barrier resin having the above-mentioned characteristics, one having 1 carbon atom
Polyamides having a number of amide groups per 00 in the range of 5 to 50, especially 6 to 20; eg nylon 6, nylon 6,6, nylon 6 / 6,6 copolymer, metaxylylene adipa Mid, nylon 6,10, nylon 11, nylon 12, nylon 13 and the like are used. Further, a PET film or a nylon film having a coating film made of an inorganic oxide such as aluminum oxide or silicon oxide is used.

The cushion layer has a function of smoothing the uneven surface of the oxygen absorbing layer, and conventionally low density polyethylene, linear low density polyethylene and the like have been used. In the present invention, an ethylene-propylene copolymer having a melting point of 115 ° C. or higher is preferable for the heat seal layer and the cushion layer from the viewpoint of adaptability to retort. It is preferable because it hides the color of the agent and makes the appearance beautiful. The thickness of the heat-sealing layer is 10 μm to 50 μm. If the thickness is 10 μm or less, it becomes impossible to secure a predetermined sealing strength, and if it is 50 μm or more, the oxygen absorption rate is lowered, which is not preferable. An adhesive layer is arranged between the layers as necessary.

The pouch of the present invention includes a standing pouch, but in the case of a standing pouch, the oxygen absorbent of the copper material forming the pouch body is adjusted by the amount of the oxygen absorbent of the bottom material forming the bottom of the pouch. Smaller than the compounding amount of. When the pouch bottom is dropped, it is directly impacted and impact resistance is particularly required. Therefore, the oxygen absorbent content of the bottom is smaller than that of the body of the body.

[0012]

EXAMPLES The present invention will be specifically described with reference to the following examples. Example 1 A 12 μm PET film was dry laminated with a 7 μm aluminum foil layer and a 30 μm ethylene-propylene block copolymer film as a cushion layer using a urethane adhesive. An oxygen absorption layer obtained by blending 80% by weight of an ethylene-propylene block copolymer, 10% by weight of maleic acid-modified polypropylene, and 10% by weight of an iron-based oxygen absorber on the surface of the ethylene-propylene block copolymer film of this laminated film. And a heat seal layer prepared by blending ethylene-propylene block copolymer resin with 30% by weight of a titanium-based colorant are co-extruded and laminated, and 12 μm PET / 7 μm aluminum foil / 30 μm cushion layer / 25 μm oxygen absorption layer / 30 μm heat seal. A multilayer film having a layer structure of layers was prepared. Using this multi-layer film, a pouch of 130 mm × 170 mm was prepared, and 160 cc of water and 20 cc of oil were filled in the pouch to form a four-sided sealed contents-filled package. The package was retorted at 120 ° C. for 30 minutes, and then the seal strength was measured. The same pouch was filled with 180 cc of water, retorted at 120 ° C. for 30 minutes, cooled to 5 ° C., and then subjected to a drop test. The results are shown in Table 1.

Example 2 to Comparative Example 9 A pouch was obtained in the same manner as in Example 1 except that the composition of the oxygen absorbing layer was changed as shown in Table 1. In addition, in Example 7 and Comparative Example 8, the heat seal layer was changed to high density polyethylene. In Example 2 and Comparative Example 2, the oxygen absorbing layer and the heat seal layer were sandwich laminated.

[0014]

[Table 1]

(Note) 1. Pouch composition and size: 12μPET / 7μAL /
30μ cushion layer / 25μ oxygen absorption layer / 30μ heat seal layer 2. Seal strength: Content (water / oil = 160cc / 20c
After c) is filled and retort at 120 ° C. for 30 minutes, the seal strength (MD / TD) (15 mm width) is measured. (Pulling speed: 300mm / min.at 23 ℃) 2.3kg / 15 according to the regulation of retort pouch (Ministry of Health and Welfare Notification 370).
must be at least mm. 3. Drop test: Fill the contents (water = 180cc) and
After retorting at 20 ° C. for 30 minutes, 30 bags are dropped vertically to check the number of broken bags. (Drop height: 120 cm,
Number of drops: 10 times, product temperature: 5 ° C) 4. The EP block copolymer in the table indicates an ethylene-propylene block copolymer. 5. The EP random copolymer in the table indicates an ethylene-propylene random copolymer. 6. LLDPE in the table indicates linear low density polyethylene. 7. The EB copolymer in the table indicates an ethylene-butene copolymer. 8. EP-R in the table indicates ethylene-propylene rubber. 9. HDPE in the table indicates high density polyethylene. 10. PP and PE in the table represent polypropylene and polyethylene, respectively. 11. () In the table indicates the blending amount (% by weight) with respect to the oxygen absorption layer. 12. The seal strengths and drop strengths of Comparative Examples 1 to 9 are practically legally unusable. Comparative Example 1 is an example in which the seal strength and the drop impact strength were lowered because the amount of the oxygen absorbent added was too large. Comparative Example 2
No. 8 is an example in which the amount of maleic acid-modified polyolefin added was 0 or 1, which was small, so that the seal strength and the drop impact strength were lowered. Comparative Example 9 is an example in which the maleic acid-modified polypropylene was added in an excessively large amount, and thus the seal strength and the drop impact strength were lowered.

[0016]

INDUSTRIAL APPLICABILITY The present invention has the effects of removing oxygen in a container, excellent in long-term storage of the contents and flavor retention, and remarkably excellent retortability.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yoshiaki Otsuka             1-3-1 Uchisaiwaicho, Chiyoda-ku, Tokyo Made by Toyo             Can Co., Ltd. F term (reference) 3E064 AA01 AB25 BA16 BA24 BB03                       BC08 BC18 BC20 EA07 EA17                       EA18 EA30                 3E067 AA03 AA04 AA11 AB01 BA12A                       BB14A BB25A CA06 CA24                       EA06 EE48 FA01 FB13 FC01                       GB13 GD02                 3E086 AA23 AD01 BA04 BA15 BB05                       BB84 CA03                 4F100 AA17A AA21D AB01C AB10                       AB33 AK03C AK04B AK04C                       AK04D AK04J AK05C AK07B                       AK07C AK07D AK07J AK09C                       AK09J AK42 AK63C AL02B                       AL02C AL02D AL03C AL05C                       AL06C AL09C BA04 BA07                       BA10A BA10D CA09C CA13D                       DE01C EH20 EH23 GB23                       JA04B JA04D JD03A JD14C                       JK11B JL12D YY00C YY00D

Claims (9)

[Claims] 1. An oxygen absorbing layer in which an oxygen absorbing agent is blended with an olefin resin containing 2 to 40% of a modified polyolefin resin on one surface of an outer surface layer formed by dry lamination of at least one oxygen barrier layer and a cushion layer. A pouch for a retort, which is formed of a laminated film provided with an inner surface layer formed by coextrusion or sandwich lamination of a heat-sealable layer. 2. The pouch for a retort according to claim 1, wherein the oxygen barrier layer is a plastic film having a coating made of an inorganic oxide. 3. The pouch for retort according to claim 1, wherein the oxygen absorbing layer is a layer containing 5 to 40% of metal or metal compound powder. 4. The oxygen-absorbing layer has an ethylene-propylene block copolymer, an ethylene-propylene random copolymer, a linear low-density polyethylene, a high-density polyethylene,
A layer formed of a composition in which a metal or a metal compound powder is blended as an oxygen absorber into a blended product obtained by blending one or more modified polyolefin resins selected from ethylene-propylene rubber and ethylene-butene copolymer. The pouch for retort according to any one of claims 1 to 3. 5. The pouch for retort according to claim 1, wherein the modified polyolefin resin is one or more resins selected from maleic acid modified polypropylene and maleic acid modified polyethylene. 6. The cushion layer and the heat-sealable layer disposed on the innermost surface are layers having an ethylene-propylene block copolymer having a melting point of 115 ° C. or higher.
The pouch for a retort according to any one of 1. 7. The pouch for retort according to claim 1, wherein the heat sealable layer disposed on the innermost surface is a layer containing a white pigment such as titanium white. 8. The thickness of the oxygen absorbing layer is 10 μm to 40 μm.
And the thickness of the heat sealable layer disposed on the innermost surface is 1
The pouch for retort according to any one of claims 1 to 7, which has a size of 0 µm to 50 µm. 9. The pouch for a retort according to any one of claims 1 to 8, wherein the amount of the oxygen absorbent compounded in the bottom material forming the pouch bottom is the same as that of the body material forming the pouch body. Standing pouch for retort with smaller amount than oxygen absorber.