JPH08132573A - Oxygen absorbing laminate - Google Patents

Abstract

PURPOSE: To prevent oxidation of a food to a high degree by simple structure by a method wherein a polyolefin layer is made to lie between a resin layer having an oxygen absorbing function and an oxygen barrier, a sealant layer is provided on a resin layer side having the oxygen absorbing function, and an outer layer is provided on the oxygen barrier side. CONSTITUTION: A polyolefin layer 3 is made to lie between a resin layer 2 having a deoxidizing function and an oxygen barrier 5, a sealant layer 1 is provided on the resin 2 side having the deoxidizing function, and an outer layer 7 is provided on the oxygen barrier 5 side. That is, a layer wherein an iron based oxygen scavenger is kneaded in a polyolefin resin is formed as the oxygen absorbing resin layer 2. The layer is put between the polyolefin layer 3 and the sealant layer 1. For example, polyvinyliden chloride resin as an air- intercepting layer is laminated 7 outside a container. Consequently, there is no fear of obstructing the oxygen absorbing function by mixing, for example, an iron content and others in the barrier. Further, when nitrogen-replaced packaging is carried out for the container, prevention of oxidization and bacteriostasis are effectively exerted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated body having an oxygen absorbing function and a container comprising the laminated body, which can prevent the oxidation of foods and the propagation of aerobic microorganisms.

[0002]

2. Description of the Related Art Conventionally, a sachet type oxygen absorber (oxygen absorber) is now widely used as an antioxidant for foods, such as oily foods, and for preventing propagation of aerobic microorganisms, such as rice cakes. This storage technology has been developed in Japan and has been widely applied mainly to small lot products because it does not require expensive equipment.

The performance of the oxygen scavenger is greatly influenced by the water activity and air capacity of the target food and the oxygen barrier property of the packaging material. This determines the prescription of the oxygen scavenger and the material and size of the pouch. On the other hand, in the current barrier container, aluminum is the most effective against the invasion of oxygen from the outside, but it is necessary to remove the internal oxygen. Also,
The actual tray is a plastic molded product, and even the material with the highest oxygen barrier will be slightly permeable.

[0004] Although retort cooked rice has been the main stream of processed cooked rice on the market, the taste is not so good and the packaging form looks good due to heat cooking sterilization, which is different from the usual cooked condition after packaging, in view of the recent gourmet orientation. Was bad. Therefore, recently, cooked rice has been commercialized under normal rice cooking conditions and filled in an aseptic molding container in an aseptic environment.

However, since the method of commercialization that is currently performed is not completely sterile, it is necessary to prevent the growth of aerobic bacteria by absorbing oxygen. In reality, nitrogen replacement alone completely removes oxygen from the container. Since it cannot be done, oxygen in the container is removed by using it together with an oxygen scavenger. However, in this case, a deoxidizing agent filling step is required, and in some cases, pH adjustment is required to enhance the bacteriostatic effect.

On the other hand, in the barrier containers currently in circulation, aluminum is the most effective against the invasion of oxygen from the outside, but it is necessary to remove oxygen inside the container, and therefore nitrogen gas replacement is necessary. Etc., but some oxygen remains. In addition, even if a material having the highest oxygen barrier property is used for the plastic tray, external oxygen slightly permeates.

Therefore, it is conceivable to use a tray composed of an oxygen-absorbing laminated body as shown in Japanese Patent Publication No. 6-51397. However, when the oxygen-absorbing layer and the barrier layer are adjacent to each other, the oxygen absorber is mixed in the barrier layer. (The iron content in the oxygen absorption layer migrates to the barrier layer), which may impair the oxygen absorption function.

[0008]

DISCLOSURE OF THE INVENTION According to the present invention, in imparting an oxygen absorbing function to a container, a polyolefin layer is provided between the oxygen absorbing layer and the barrier layer so that iron in the oxygen absorbing layer does not migrate to the barrier layer. It is an object of the present invention to provide a sheet made of the above laminated body and a container formed from the sheet.

[0009]

The present invention has been conceived in order to solve the above problems, and a polyolefin layer is interposed between a resin layer having a deoxidizing function and an oxygen barrier layer, and the deoxidizing function is Is an oxygen-absorbing laminate having a sealant layer on the resin layer side and an outer layer on the oxygen barrier layer side.

More specifically, a layer in which an iron-based oxygen scavenger is kneaded into a polyolefin resin is formed as an oxygen absorbing resin layer, and this layer is sandwiched between the polyolefin layers, and an air blocking layer is formed of polyvinylidene chloride resin or ethylene. Laminating the vinyl alcohol-based copolymer on the outside of the container. In order to adjust the speed at which the moisture from the internal food reaches the oxygen absorbing layer in the sealant layer, a hygroscopic agent such as calcium carbonate or zeolite is added, and it is preferable to color it with titanium white in order to cover the oxygen absorbing agent in appearance. . Further, as the base material of the outermost layer, a colorant such as titanium white may be used in the polyolefin resin in order to conceal the oxygen absorbent as in the sealant layer.

[0011]

[Function] Since there is a polyolefin layer between the oxygen absorption layer and the barrier layer, there is no risk that, for example, iron contained in the oxygen absorption layer will be mixed into the barrier layer and inhibit the oxygen absorption function. . In addition, since it has an excellent oxygen absorption function when used as a container, the imperfection of oxygen absorption is resolved when nitrogen substitution packaging is performed, and antioxidant and bacteriostatic action are effectively exhibited, and deoxidation is performed. There is no need to fill the agent in a separate process, and the material cost as a package and the filling process can be reduced, so that the material and running costs can be reduced.

The embodiments of the present invention will be described below.

[0013]

[Examples] Using a coextrusion multilayer sheet manufacturing apparatus, the following resins were simultaneously extruded by five extruders, and after the melted resins were joined, they were extruded into a sheet by a T die and cooled to give a total thickness of 500μ A multilayer sheet of layers was produced. The oxygen-absorbing resin layer is made of polypropylene resin mixed with 30% iron-based oxygen scavenger (comprising iron powder with a specific gravity of 2.0 or more and a surface area of 0.5 or more and salt) in low density polyethylene. is there. The gas barrier layer is saponified ethylene vinyl acetate copolymer (EVOH ethylene content 32%, saponification degree 99
%). As the adhesive resin, a thin polypropylene resin having a thickness of about 5 μ is sandwiched from both sides of the gas barrier layer. The innermost layer is made by adding TiO ₂ as a coloring agent and a hygroscopic agent to polypropylene. The outermost layer is made of polypropylene to which TiO ₂ is added as a colorant. The thickness of each layer of the obtained multilayer sheet was manufactured uniformly, and was as follows. Inner layer milky white polypropylene 80μ (1) / oxygen absorption layer 130μ (2) /
Polypropylene layer 30μ (3) / Adhesive layer 5μ (4) / E
The VOH layer was 40 μ (5) / adhesive layer 5 μ (6) / outer layer opalescent polypropylene 250 μ (7). This is illustrated in FIG.

From the obtained multilayer sheet, a rectangular parallelepiped tray container having rounded corners as shown in FIG. 2 was formed by plug-assisted vacuum forming, filled with 200 g of cooked rice and replaced with nitrogen gas, and then the lid material PET 12 μ / AL 9 μ. / PP
Seal with 50μ. This was stored at room temperature and the change in oxygen concentration with time was measured. As shown in (Table 1), the initial oxygen concentration of about 0.3% fell below the detection limit (0.01 ppm) in one week, and this deoxidized state was maintained for 6 months. It turned out.

Comparative Example 1 Ordinary opalescent PP 80 μ (8) / oxygen absorbing resin layer 13
A 0 μ (9) / adhesive layer 5 μ / EVOH 40 μ (10) / adhesive layer 5 μ / milky PP 80 μ (11) component sheet was co-pressed to prepare a multi-layer sheet in the same manner as in the example. This is shown in FIG. A tray of the same type as that of the example was prepared by the vacuum forming method. The tray was filled with 200 g of cooked rice, replaced with nitrogen gas, and sealed with the same lid material as in the example. This was stored at room temperature in the same manner as in the example, and the change in oxygen concentration with time was measured. The test results are shown in (Table 1). From these results, compared with the examples, when the initial oxygen concentration was one week, oxygen was not absorbed so much, and
It was below the detection limit after a month. This causes the rice to be slightly oxidized during storage.

<Comparative example 2> Ordinary milky white PP 220 μ (12) / adhesive layer 5 μ / E
VOH 40μ (13) / Adhesive layer 5μ / Milk white PP 250μ
A coextrusion multilayer sheet having the constitution (14) was prepared by the manufacturing apparatus as in the example. This is shown in (FIG. 4). A tray of the same type as that of the example was prepared by the vacuum forming method. The tray was filled with 200 g of cooked rice, replaced with nitrogen gas, and sealed with the same lid material as in the example. This was stored at room temperature in the same manner as in the example, and the change in oxygen concentration with time was measured. The test results are shown in (Table 1). From these results, it was found that the initial oxygen concentration was almost unchanged in one week and below the detection limit after 6 months as compared with the examples. This means that the cooked rice was oxidized.

<Comparative Example 3> Ordinary milky white PP 220 μ (12) / adhesive layer 5 μ / E
VOH 40μ (13) / Adhesive layer 5μ / Milk white PP 250μ
A coextrusion multilayer sheet having the constitution (14) was prepared by the manufacturing apparatus as in the example. This is shown in FIG. A tray of the same type as that of the example was prepared by the vacuum forming method. The tray was filled with 200 g of cooked rice, purged with nitrogen gas, filled with an oxygen absorber, and sealed with a lid material similar to that of the example. This was stored at room temperature in the same manner as in the example, and the change in oxygen concentration with time was measured. The test results are shown in Table 1. From these results, it was found that the initial oxygen concentration was almost unchanged in one week and below the detection limit after 6 months as compared with the examples. This means that the cooked rice was oxidized.

[0018]

[Table 1]

As a result of the above-mentioned test, the examples have excellent oxygen absorption ability, and as shown in (Table 2), the cost is not high and the practical effects are recognized. Although the example 2 has a low cost, the oxygen absorption capacity is not sufficient, and the comparative example 3 has a sufficient oxygen absorption capacity, but there is a problem in practical use in that the cost is high.

[0020]

[Table 2]

In the above embodiments, the case where the sheet made of the oxygen-absorbing laminate of the present invention is vacuum-formed into a tray shape has been described, but the sheet can be used as a bag by adjusting the thickness of the sheet.

[0022]

The bag made of the deoxidizing multilayer structure of the present invention,
In the molded container, the oxygen absorption layer does not coexist with the barrier layer (the iron content in the oxygen absorption layer does not migrate to the barrier layer), so the oxygen absorption rate is faster than before, and it is possible to highly prevent food oxidation. It is possible to prevent the barrier property of the container from being lowered by retort sterilization. In addition, the cost can be reduced compared to the case where a conventional oxygen scavenger is used together, and therefore there is no step of filling a separate member, so there is no need to use a large-scale device, and the conventional filling / packaging method is used. It can be carried out easily without changing the process.

Further, since the function of the oxygen absorbing layer does not deteriorate in the package using the container made of the laminate sheet of the present invention, the sterilized state of the contents is maintained for a long period of time, and moreover, the oxygen absorbing layer is used for absorbing oxygen. Cost is not increased because no separate member is stored.

[0024]

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a seat structure of an embodiment of the present invention.

FIG. 2 is a perspective view of a tray used in Examples and Comparative Examples of the present invention.

FIG. 3 is a cross-sectional view showing a seat structure of Comparative Example 1.

FIG. 4 is a cross-sectional view showing sheet configurations of Comparative Examples 2 and 3.

[Explanation of symbols]

 1,7,8,12,14: Milky white polypropylene 2,9: Oxygen absorbing layer 3: Polypropylene 4,6: Adhesive layer 5,10, 13: Gas barrier layer

Claims (3)

[Claims] 1. An oxygen comprising a polyolefin layer interposed between a resin layer having an oxygen absorbing function and an oxygen barrier layer, a sealant layer being provided on the resin layer having the oxygen absorbing function, and an outer layer being provided on the oxygen barrier layer side. Absorption laminate. 2. The oxygen-absorbing laminate according to claim 1, wherein the layer having an oxygen-absorbing function is formed by kneading a masterbatch obtained by kneading 50% or less of an oxygen-absorbing functional material in a polyolefin resin. 3. The oxygen-absorbing laminate according to claim 1, wherein the sealant layer contains a composition having good water absorption and permeability.