JP6225345B2 - Oxygen-absorbing film, oxygen-absorbing laminate, oxygen-absorbing packaging material comprising oxygen-absorbing laminate, and oxygen-absorbing resin composition - Google Patents

Description

  The present invention relates to an oxygen-absorbing film, an oxygen-absorbing laminate, an oxygen-absorbing packaging material composed of an oxygen-absorbing laminate, and an oxygen-absorbing film suitable as packaging materials for foods, drugs, pharmaceuticals, cosmetics, electronic parts and the like. The present invention relates to a resin composition.

  An oxygen absorbent is enclosed in a package in not only foods and drugs but also cosmetics and electronic parts. Oxygen remaining or gradually penetrating into the package may change the active ingredient of the product, or may change the flavor and color of the product, thereby significantly reducing the commercial value of the product. An oxygen absorbent is used to remove oxygen in the package.

  So far, as oxygen absorbers, oxygen-absorbing agents containing iron powder as a reaction main agent, ascorbic acid, gallic acid and other easily oxidizable substances have been allowed to coexist in the package as antioxidants.

  Further, Patent Documents 1 to 3 include a resin composition having an oxygen absorption capacity composed of an inorganic oxide having an oxygen defect and a thermoplastic resin, and a packaging including a layer formed from a resin having an oxygen absorption capacity. Laminates have been proposed.

JP 2005-105194 A JP 2006-130717 A JP 2006-131242 A

  However, since the laminated body including the oxygen absorbing layer described in Patent Documents 1 to 3 has a low oxygen absorption amount, a laminated body having a higher oxygen absorbing ability has been demanded.

  Patent Documents 1 to 3 specifically describe a resin composition having an oxygen absorption capacity including an inorganic oxide having an oxygen defect exceeding 50% by weight and a laminate including an oxygen absorption layer made of the resin composition. Not disclosed.

  The resin composition containing a large amount of cerium oxide having the most oxygen defects disclosed in Patent Documents 1 to 3 is a resin composition in which 65 parts by weight of cerium oxide having oxygen defects is blended with 100 parts by weight of the thermoplastic resin. (Containing cerium oxide having 39.4% by weight of oxygen defects in the resin composition).

  Regarding the reason why the content of the inorganic oxide having oxygen defects in the resin composition having oxygen absorption capacity or the oxygen absorption layer is 50% by weight or less, Patent Documents 2 and 3 have oxygen defects in the oxygen absorption. It is described that when the cerium oxide content is more than 50% by weight, the oxygen absorbing layer becomes brittle and the strength of the packaging laminate may not be maintained.

  In view of the above circumstances, the present invention provides an oxygen-absorbing film containing more than 50% by weight of cerium oxide having an oxygen defect, an oxygen-absorbing laminate using the oxygen-absorbing film, and an oxygen-absorbing film. An object is to provide an oxygen-absorbing packaging material comprising a laminate and a resin composition useful for forming an oxygen-absorbing film.

  The present inventors manufactured a resin composition in which the content ratio of cerium oxide having an oxygen defect was changed using a thermoplastic resin generally recommended by a resin manufacturer and suitable for film formation. An attempt was made to form a film of the obtained resin composition, and as a result, an increase in the content ratio of cerium oxide having oxygen defects caused a problem that film formation became difficult. In particular, when the blending ratio of cerium oxide having oxygen defects exceeds 50% by weight, an oxygen-absorbing film cannot be obtained.

  However, as a result of further research, the present inventors have found that even if a large amount of cerium oxide having oxygen defects is contained, film formation is possible if the resin composition has high fluidity. The present invention has been completed.

  The present invention comprises an oxygen absorption layer containing a thermoplastic resin and cerium oxide having oxygen defects, and a resin layer provided on both surfaces of the oxygen absorption layer, and the cerium oxide having oxygen defects has a weight of 50% by weight. Provided is an oxygen-absorbing film contained in a range of more than 60% by weight.

  The present invention also provides an oxygen-absorbing laminate in which a gas barrier film and / or a substrate film is laminated on the above-described oxygen-absorbing film, and an oxygen-absorbing packaging material in which the oxygen-absorbing laminate is formed.

The present invention also includes a thermoplastic resin and cerium oxide having oxygen defects, and includes cerium oxide having oxygen defects in the range of more than 50% by weight and less than 60% by weight, and the melt flow rate is Provided is a resin composition useful for forming an oxygen-absorbing film having a range of 1.0 to 18.0 g / 10 min.
Furthermore, this invention provides the resin composition for inflation which consists of the above-mentioned resin composition.

  Since the oxygen-absorbing film of the present invention contains more than 50% by weight of cerium oxide having oxygen defects in the oxygen-absorbing layer, it has a high oxygen-absorbing ability.

  The oxygen-absorbing laminate and the oxygen-absorbing packaging material of the present invention have a high oxygen-absorbing capacity, and by using these, it is possible to prevent deterioration of the package contents due to oxygen deterioration.

  Since the resin composition of the present invention has fluidity and molding strength suitable for film formation and contains a high content of cerium oxide having oxygen defects, it is possible to form a packaging material having a high oxygen absorption capacity. is there.

It is a schematic sectional drawing which shows the oxygen absorptive film which concerns on Embodiment 1 of this invention. It is a schematic sectional drawing which shows the oxygen absorptive laminated body which concerns on Embodiment 2 of this invention. It is a graph which shows the relationship between the melt flow rate of the resin composition obtained from the Example, and the melt flow rate of a thermoplastic resin.

  Hereinafter, embodiments of the present invention will be described.

(Embodiment 1)
As shown in FIG. 1, the oxygen-absorbing film 1 of the present invention is composed of an oxygen-absorbing layer 2 and resin layers 3 provided on both surfaces of the oxygen-absorbing layer. The oxygen absorption layer 2 is composed of a thermoplastic resin and cerium oxide having oxygen defects, and the oxygen absorption layer 2 contains cerium oxide having oxygen defects in a range of more than 50 wt% and less than 85 wt%. . The amount of cerium oxide having oxygen defects in the oxygen absorbing layer is preferably in the range of 51 wt% to 82 wt%.

  The oxygen-absorbing film 1 having the above-described structure includes an intermediate resin composition that contains more than 50% by weight of cerium oxide having oxygen defects and has a melt flow rate in the range of 1.0 to 18.0 g / 10 min. It can be obtained by forming a layer and forming the resin layer 3 on both sides. The resin layers 3 provided on both sides are layers provided to protect the oxygen absorbing layer 2 and improve the film forming strength. The film formation may be a multi-layer film having a three-layer structure using, for example, a multilayer inflation machine.

  The melt flow rate is an index indicating the fluidity of the resin or resin composition, and is defined in JISK7210. In the present invention, the melt flow rate is measured at a temperature of 190 ° C.

  The resin composition contains a thermoplastic resin and cerium oxide having oxygen defects, and contains 50% by weight or more of cerium oxide having oxygen defects, and 1.0 to 18.0 g / 10 min. Having a melt flow rate in the range. The melt flow rate of the resin composition is preferably in the range of 1.81 to 17.27 g / 10 min.

Cerium oxide having oxygen defects is a substance obtained by heating cerium oxide in a reducing gas such as hydrogen, carbon monoxide, acetylene, etc., and has a structure similar to fluorite, and has the general formula CeO. It is represented by _2-x . X representing the degree of oxygen defects is in the range of greater than 0 and less than or equal to 1. If it exceeds 1, the crystal structure cannot be maintained, which is not preferable.

  A resin composition having an oxygen defect-containing cerium oxide (hereinafter simply referred to as “cerium oxide”) content exceeding 50% by weight and having a melt flow rate outside the above range cannot be used for film formation.

  In order to set the melt flow rate of the resin composition having a cerium oxide content exceeding 50% by weight within the above-mentioned range, a thermoplastic resin having a melt flow rate exceeding 8.0 g / 10 min is kneaded with cerium oxide. There is a need to produce a composition. The range of the melt flow rate of a preferable thermoplastic resin is 8.2 to 55.0 g / 10 min. More preferably, it is the range of 8.4-54.2 / 10min.

  When a thermoplastic resin having a melt flow rate lower than the lower limit of the above-described range is used, the melt flow rate of the resulting resin composition becomes too low, the torque load of the extruder becomes high, and the extruder stops. This is not preferable. If a thermoplastic resin having a melt flow rate higher than the upper limit of the above range is used, the melt flow rate of the resulting resin composition becomes too high, the extrusion amount is not stable, the film breaks during film formation, etc. Since the film becomes difficult, it is not preferable.

  Examples of the thermoplastic resin include polyethylene resins such as linear low density polyethylene (LLDPE), low density polyethylene (LDPE), medium density polyethylene (MDPE), and high density polyethylene (HDPE). In production of the resin composition, a material having a melt flow rate in the above-described range may be selected from these thermoplastic resins.

  The resin composition can be obtained by blending and kneading the selected thermoplastic resin so as to contain more than 50% by weight of cerium oxide. Kneading can be performed using a mixer or an extruder such as a single screw extruder or a twin screw extruder.

  The resin composition having a melt flow rate in the range of 1.0 to 18.0 g / 10 min can contain cerium oxide having oxygen defects in excess of 50% by weight, but the upper limit is 85. Less than% by weight. This is because when the content is 85% by weight or more, the melt flow rate of the resin composition becomes lower than the lower limit of the above range.

  When the resin composition having a melt flow rate in the range of 1.0 to 18.0 g / 10 min is used as an intermediate layer and the resin layer 3 is provided on both sides, the oxygen absorbing layer 2 has a thickness of 10 to 140 μm. An oxygen-absorbing film in the range can be formed.

  The resin layers 3 provided on both surfaces of the oxygen absorbing layer may be formed of the same thermoplastic resin on both surfaces, or may be formed by selecting thermoplastic resins having different components. The melt flow rate of the thermoplastic resin of the resin layer 3 may be selected within a range suitable for film formation recommended by the resin manufacturer. Specifically, any thermoplastic resin having a melt flow rate in the range of 0.3 to 8.0 g / 10 min may be used.

As described above, since the oxygen absorption layer 2 contains more than 50 wt% and less than 85 wt% cerium oxide, the oxygen absorption capacity per unit area is high as long as the thickness is the same as that of the conventional film. Moreover, since it forms from the resin composition which has sufficient film forming characteristic, the thickness of an oxygen absorption layer can be set as 10-140 micrometers oxygen-absorbing film. Since a thin film can be formed, the total thickness does not become too thick even if a sealant layer is added, and the effect of increasing the degree of freedom in terms of configuration and processing is also achieved.
(Embodiment 2)
A gas barrier film 5 and / or a base film 6 can be laminated on the oxygen-absorbing film 1 to form an oxygen-absorbing laminate 4.
FIG. 2 shows an oxygen-absorbing laminate 4 in which a gas barrier film 5 and a base film 6 are laminated on the resin layer 3 of the oxygen-absorbing film 1, and the gas barrier film 5 or the base film 6 is laminated on the oxygen-absorbing film 1. Either of these may be laminated.

  By laminating the gas barrier film 5 and / or the base film 6, in addition to being able to block the intrusion of gas such as oxygen, the strength of the laminate can be increased. Examples of the gas barrier film include aluminum foil, aluminum foil laminated film, aluminum vapor deposition film, alumina vapor deposition film, silica vapor deposition film, and silica alumina binary vapor deposition film. Representative examples of the base film include PET and nylon.

  As a method for laminating the gas barrier film 5 and / or the base film 6 on the oxygen-absorbing film 1, a dry laminating method, an extrusion laminating method, or the like can be used.

  The oxygen-absorbing laminate 4 of the present invention is formed into a bag with the heat-sealable thermoplastic resin layer 3 inside, a four-side sealed bag, a three-side sealed bag, a pillow bag, a gusset pillow bag, a standing bag, a box-type bag. Various forms of oxygen-absorbing packaging materials such as chuck bags and tetrapack-type seal bags can be used.

  Hereinafter, the present invention will be further described with reference to examples.

Using a Laboplast mill mixer (manufactured by Toyo Seiki) or a Laboplast mill twin screw kneading extruder (manufactured by Toyo Seiki), a thermoplastic resin and cerium oxide having oxygen defects (general formula CeO _2-x x) in a nitrogen gas atmosphere About 1.5) particles were kneaded.

  As shown in Table 1, various resin compositions were prepared by changing the type of kneading machine, the type and blending amount of the thermoplastic resin (Petrocene series, low-density polyethylene manufactured by Tosoh Corporation), and the blending amount of cerium oxide ( Examples 1 to 14 and Comparative Examples 1 to 5).

  The kneading method 1 described in Table 1 is a method using a lab plast mill mixer, and the kneading method 2 is a method using a lab plast mill twin-screw kneading extruder.

  The melt flow rate (expressed as MFR in the table) of the obtained resin composition was measured at a temperature of 190 ° C. using a melt indexer manufactured by Techno Seven Co., Ltd. under the conditions specified in JISK7210. did.

  The film forming property was evaluated by the following procedure.

The obtained resin composition (resin compositions of Examples 1 to 14 and Comparative Examples 1 to 5) was used as an intermediate layer, and an oxygen-absorbing film having a three-layer structure in which a thermoplastic resin layer was provided on the inner layer and the outer layer was molded. .
For forming, a film having an inner layer / oxygen absorbing layer / outer layer of 10/30/10 μm and a total thickness of 50 μm was produced while flowing nitrogen gas using a multilayer inflation machine.
The thermoplastic resin used for the inner layer and the outer layer is Tosoh Petrocene 180 (melt flow rate 2.0).

In the process of forming an oxygen-absorbing film having a three-layer structure using a multi-layer inflation machine, the case where the film could be formed without any problem was indicated as “◯”. On the other hand, when the amount of extrusion was not stable, torn, the torque load of the machine was high, and the film could not be stably formed, such as being stopped. The results are shown together in Table 1, and FIG. 3 is a graph showing the relationship between the melt flow rate of the resin composition and the melt flow rate of the thermoplastic resin.
A film having an inner layer / oxygen absorbing layer / outer layer of 10/10/10 μm and a total thickness of 30 μm could be stably formed.

The following can be understood from Table 1 and FIG.
(1) If the oxygen defect-containing cerium oxide is contained in an amount of 51% by weight to 82% by weight and the melt flow rate is in the range of 1.81 to 17.27 g / 10 min, the resin composition has good film forming properties. about.
(2) Even if the melt flow rate of the thermoplastic resin exceeds 8.0 g / 10 min, it is difficult to form a film of cerium oxide having 85% by weight of oxygen defects.

(Measurement of oxygen absorption)
The example which measured the oxygen absorption amount of the oxygen absorptive film and the oxygen absorptive laminated body is shown (Examples 15 and 16 and Comparative Examples 6 and 7).

(Example 15)
Using the film of Example 10, the oxygen absorption was measured by the following method.
A 25 cm ² oxygen-absorbing film was put into a PET / aluminum foil / PE bag, and sealed in a tetrapack type so that the volume became 15 mL, that is, 15 mL of air. After 30 days at room temperature, the oxygen concentration of the oxygen-absorbing film is measured by measuring the oxygen concentration in the bag by inserting the measuring needle of a pack master RO-103 (diaphragm galvanic cell type oxygen sensor manufactured by Iijima Electronics Co., Ltd.) into the tetrapack. Was calculated.

(Example 16)
A 9 μm-thick aluminum foil (alloy aluminum made by Sumi Light Aluminum Foil) was dry-laminated on a 12 μm-thick PET film (E5100 manufactured by Toyobo). The aluminum foil surface and the oxygen-absorbing film of Example 10 were dry laminated to produce an oxygen-absorbing laminate.
The oxygen absorption amount of the oxygen-absorbing laminate was measured by the method described in Example 15.

(Comparative Examples 6 and 7)
Oxygen-absorbing film in which the ratio of cerium oxide having oxygen defects in the oxygen-absorbing layer is 20,40% by weight (the thermoplastic resin of the oxygen-absorbing layer is Tosoh Petrocene 180, the resin layers on both sides are also Petrocene 180, the kneading method 1, Regarding the thickness of each layer (10/30/10 μm) and the film forming conditions are the same as in Example 1, the oxygen absorption amount was measured in the same manner as in Example 15.

Table 2 shows the results of oxygen absorption amounts of Examples 15 and 16 and Comparative Examples 6 and 7.

  As the content of cerium oxide having oxygen defects in the oxygen absorption layer increases, the oxygen absorption amount increases.

(Measurement of oxygen absorption of oxygen-absorbing packaging materials)
The example which measured the oxygen absorption of the packaging material which made the oxygen absorptive laminated body into the bag is shown.

(Example 17)
The oxygen-absorbing packaging material has an oxygen-absorbing film surface of the oxygen-absorbing laminate of Example 16 (PET12 // AL9 // Example 10 film) and has a volume of 35 mL, that is, 35 mL. A four-side sealed bag having an inner size of 125 mm × 65 mm was prepared so that the air could enter.
After leaving the sealing bag for 30 days, the oxygen concentration in the bag was measured by inserting a measuring needle of Packmaster RO-103 (diaphragm type galvanic cell type oxygen sensor manufactured by Iijima Electronics Co., Ltd.) into the four-way sealing bag. As a result, the oxygen concentration was 0.20%.

(Comparative Example 8)
(Film formation of resin composition using melt flow rate thermoplastic resin suitable for film formation recommended by resin manufacturer)
Fabrication of a resin composition containing 50% by weight of cerium oxide having oxygen defects based on a thermoplastic resin having a melt flow rate of 4.0 g / 10 min and 8.0 g / 10 min, which is considered suitable for film formation However, although film formation was attempted, none of the films could achieve stable film formation, and a film could not be obtained.

1: Oxygen-absorbing film 2: Oxygen-absorbing layer 3: Thermoplastic resin layer 4: Oxygen-absorbing laminate 5: Gas barrier film 6: Base film

Claims (4)

An oxygen-absorbing layer containing a polyethylene resin having a melt flow rate of more than 8.0 g / 10 min but not more than 55.0 g / 10 min and cerium oxide having oxygen defects, and a resin layer provided on both surfaces of the oxygen-absorbing layer; The oxygen absorbing layer contains cerium oxide having oxygen defects in an amount of more than 50 wt% and not more than 60 wt%, and the oxygen absorbing layer has a melt flow rate of 1.0 to 18.0 g. An oxygen-absorbing inflation film formed from a resin composition in the range of / 10 min. The oxygen-absorbing inflation film according to claim 1, wherein the resin layers provided on both surfaces of the oxygen-absorbing layer contain a polyethylene-based resin having a melt flow rate in the range of 0.3 to 8.0 g / 10 min. An oxygen-absorbing laminate comprising a gas barrier film and / or a base film laminated on the oxygen-absorbing inflation film according to claim 1 or 2 .   An oxygen-absorbing packaging material obtained by bag-making the oxygen-absorbing laminate according to claim 3.

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