JP4893978B2 - Oxygen absorber - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention, resistance to swelling, to a good deoxidizing container peeling resistance and surface smoothness.
In particular, the present invention has oxygen absorbing agent has the problem that occurs deoxidizing film formulated, during long-term storage and use with the deoxidizing container formed from a sheet, the present invention is chemical and It relates to packaging technology.
[0002]
[Prior art]
Oxygen absorption by laminating other sheets not containing oxygen absorbent on oxygen absorbent film or sheet produced using oxygen absorbent resin composition in which oxygen absorbent and resin, especially thermoplastic resin are kneaded Form a container, for example, a multi-layer oxygen-absorbing packaging container that exhibits oxygen barrier properties by absorbing oxygen under conditions where moisture and heat act simultaneously, such as under boiling water heating conditions such as retort sterilization Have been proposed in JP-B-62-1824, JP-B-63-137838, JP-A-1-278335, JP-A-1-278344, JP-B-6-57319, and the like.
In this way, when the oxygen-absorbing resin composition is produced by kneading the iron-based oxygen absorbent and the thermoplastic resin, iron, which is the main component of the oxygen absorbent, and a trace amount contained in the oxygen absorbent or the resin are contained. Reacts with moisture to generate hydrogen.
This generation of hydrogen is not preferable because it causes a risk of ignition during the production of pellets, and this hydrogen causes problems such as foaming the pellets and causing unevenness in the sheet in the subsequent sheet forming step. Cause.
The hydrogen generation suppression measures the oxygen absorber, there can be for oxygen absorbing agent used for the oxygen absorber sachet packaging conventionally existing, but the method according to the addition of the alkaline substance in up (Japanese 61- No. 28374) has been proposed.
[0003]
In order to suppress the hydrogen generation of the oxygen absorbent for the oxygen-absorbing resin, the present inventors applied the above-mentioned proposal to produce an oxygen absorbent to which sodium phosphate was added as an alkaline substance. A sheet containing an agent and another sheet not containing an oxygen absorbent were laminated to produce a multilayer packaging container.
This manufacturing method has solved the problem of hydrogen generation during pellet production and pellet foaming due to this, but the addition of sodium phosphate causes a problem that is completely different from the hydrogen generation of oxygen absorbers. did.
That is, during the long-term storage of the packaging container obtained by the manufacturing method, swelling of the oxygen absorbent-containing layer, surface unevenness and peeling of the boundary portion of the lamination due to this occurred.
Therefore, the hydrogen generation suppression measures proposed so far by adding alkaline substances are applied to oxygen-absorbing films containing oxygen absorbents and packaging containers formed of sheets , which are the technical field to which the present invention belongs. This is a proposal for an oxygen absorber of a sachet type that has been used conventionally, and cannot be applied as it is to the oxygen absorbent for the intended purpose of the present invention . It causes unexpected problems.
[0004]
[Problems to be solved by the invention]
As a result of various studies to solve the above-mentioned problems, the present inventors have focused on the solubility in water of an alkaline material added to iron powder and studied various alkaline materials.
As a result, sodium chloride is selected as an auxiliary agent for oxygen absorption by iron powder, and the alkaline substance to be added is an insoluble substance in water, that is, an alkaline substance having a solubility in water at a temperature of 25 ° C. of 10 wt% or less. By using a certain calcium hydroxide, the above-mentioned problems were solved, and it was found that the oxygen absorbing layer in the multilayer container containing the oxygen absorbent did not swell, the lamination boundary peeled off, or the surface layer film did not crack. .
Accordingly, the oxygen absorber was obtained with proper performance as good deoxidizing container and its raw material.
[0005]
An object of the present invention, suppresses the hydrogen generation in the deoxidizing container, after long-term storage or after heat sterilization deoxidizing container, without generating irregularities on the surface, can maintain excellent appearance characteristics It is to provide a deoxygenating container.
[Means for Solving the Problems]
[0006]
In order to achieve the above object, the invention according to claim 1 of the present invention provides:
A deoxygenating film or sheet formed from a thermoplastic resin in which an oxygen absorbent comprising 0.1 to 20 parts by mass of sodium chloride and 0.05 to 2 parts by mass of calcium hydroxide is added to 100 parts by mass of iron powder. To be at least part of the container configuration
Is a deoxygenating container characterized by
[0007]
The invention according to claim 2 of the present invention is
The oxygen scavenging container according to claim 1,
The blending amount of the oxygen absorbent is
Thermoplastic resin 100 parts by weight per is characterized in that an oxygen absorbing agent 5 to 75 parts by weight.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the deoxidizing container according to the present invention will be described in detail.
<Iron powder>
The iron powder used in the present invention is not particularly limited by the production method, shape, etc., as long as it is a commonly used iron powder in an oxygen absorbent containing a metal halide or the like as a component.
In order to improve the contact with oxygen, the particle size of the iron powder is usually an average particle size of 400 μm or less, preferably 200 μm or less, particularly preferably 150 μm or less.
Too fine iron powder is preferred in the production process such as mixing and filling, because it powders and fluidity deteriorates.
[0009]
< Sodium chloride >
Sodium chloride used together with the iron powder is an auxiliary agent for oxygen absorption by the iron powder , and is used in an amount of 0.1 to 20 parts by mass with respect to 100 parts by mass of the iron powder as the main component of oxygen absorption. It is done.
When the amount of sodium chloride is less than or equal to the above lower limit value, it is difficult to obtain the expected effect of oxygen absorption performance, and the blending amount exceeding the upper limit value makes the oxygen absorption reaction too excessive, and a large amount of sodium chloride At the time of the oxygen absorption reaction, it may ooze out from the oxygen-absorbing film or sheet containing the same and adversely affect the appearance and contents or products.
[0010]
<Calcium hydroxide>
Calcium hydroxide used in the present invention is a hardly water-soluble alkaline substance having a water solubility of 10 wt% or less at a temperature of 25 ° C.
As addition amount of calcium hydroxide, it is 0.05-2 mass parts with respect to 100 mass parts of iron powder.
[0011]
<Resin>
The oxygen absorbent of the present invention is used by being blended with a resin, particularly a thermoplastic resin, and examples of the resin used include various resins.
Specifically, polyethylene, polypropylene, ethylene / propylene copolymer, polymethylpentene-1, ethylene / vinyl acetate copolymer, ethylene / vinyl alcohol copolymer, polyvinyl chloride, nylon, polyethylene terephthalate, polycarbonate One type or a mixture of two or more types, and those obtained by blending these resins and resin mixtures with elastomers.
The compounding quantity of the oxygen absorber which consists of iron powder, a metal halide, and calcium hydroxide with respect to these resin compositions is 5-75 mass parts per 100 mass parts of resin.
When the blending amount of the oxygen absorbent is less than the above range, the oxygen absorptivity is lowered, and when it is large, the moldability to the container and the characteristics as the container may be lowered.
[0012]
<Method for preparing oxygen absorbent>
As an oxygen absorber preparation method, iron powder and sodium chloride and calcium hydroxide are simply mixed by a vibration mill, a ball mill, a tube mill or the like, or the surface of the iron powder is mixed with sodium chloride and hydroxide by various means. A method of coating calcium is employed.
[0013]
<Preparation method of oxygen-absorbing resin composition>
The oxygen-absorbing resin composition is obtained by mixing the oxygen absorbent and the resin.
The mixing may be dry blend or melt blend, but in order to increase the dispersibility of the oxygen absorbent in the resin, a resin composition (masterbatch) containing a high concentration of the oxygen absorbent is first prepared. A method of mixing the master batch with the resin is preferred.
[0014]
<Preparation method of deoxygenating film, sheet and deoxygenating container>
Molded articles such as a deoxidizing film, a sheet, and a deoxidizing container can be prepared by a general method.
For example, the container is obtained by multilayer coextrusion, that is, after melt-kneading the resin composition with an extruder corresponding to each resin layer constituting the container wall, and using a multilayer multiple die such as a T-die or a circular die. Extrude into shape.
Moreover, the resin melt-kneaded by an injection machine corresponding to each resin layer is co-injected or sequentially injected into an injection mold to produce a multilayer container or a container preform.
Moreover, after preparing a lamination sheet by dry lamination, sandwich lamination, extrusion coating, etc., it can be set as a container.
After forming a parison or preform, a bottle or the like is easily prepared by pinching off it with a pair of split molds and blowing a fluid into the interior.
Films or sheets are also prepared by extrusion molding, blow molding, and the like. These films and sheets are directly stacked in a bag shape and heat-sealed with a bag-shaped container or by means such as vacuum molding, cup-shaped, tray-shaped. And so on.
[0015]
Deoxidizing container of the present invention, at least a portion of the wall is, Ru moldings der made of a resin composition in which oxygen absorbing agent is blended in the present invention, such as deoxidizing films or sheets.
The vessel wall of this deoxygenating container can take an arbitrary wall layer configuration, but generally a configuration in which a resin layer containing no oxygen absorber and a pigment is laminated on both sides of a layer formed of a deoxidizing film or sheet. However, it is preferable from the appearance characteristics of the deoxidizing container and the sanitary viewpoint of the contents.
[0016]
As an example of the configuration of the deoxidizing container, if an example of a multilayer structure is given, an outer layer made of a moisture-resistant thermoplastic resin, an adhesive resin layer, a first intermediate layer made of a gas barrier resin, an adhesive resin layer, a deoxygenating layer There is a second intermediate layer made of an oxygen-absorbing resin layer such as an adhesive film or sheet, and an inner layer made of a moisture-resistant thermoplastic resin.
In this case, the oxygen-absorbing resin layer, which varies depending on the oxygen content and deoxidizing container shape allowed for deoxidizing container, generally 10 to 200 [mu] m, in particular, have a thickness of 20~150μm preferable.
[0017]
[Action]
When calcium hydroxide, which is a poorly water-soluble alkaline substance, is added, the concentration of water on calcium hydroxide does not occur as compared with the case where an easily water-soluble substance is added.
As a result, it is estimated that inconveniences such as swelling of the oxygen-absorbing resin portion, peeling of the joining portion, and cracking of the surface layer, which occur when an easily water-soluble alkaline substance is added, can be prevented.
[0018]
【Example】
Hereinafter, the deoxygenating container of the present invention will be described in detail based on examples and comparative examples.
<Example 1>
A total of 150 kg of 100 parts of reduced iron powder produced from iron ore, 2 parts of sodium chloride (NaCl) with an average particle diameter of 20 μm, and 0.5 parts of calcium hydroxide, together with steel balls in a vibration mill with a capacity of 300 liters The mixture was shaken and pulverized for 3 hours to prepare an oxygen absorbent.
The thus prepared oxygen absorbent (present absorbent 1) was blended in 30% by mass with polypropylene (PP) having an MI of 0.6 (g / 10 min; temperature 23 ° C.) to produce pellets.
At this time, pellet foaming due to hydrogen generation was observed.
Furthermore, the present invention absorbent 1 blended polypropylene (PO1) is used as an intermediate layer, and white PP obtained by blending 8% by mass of titanium white with PP having MI of 0.6, and two types and three layers (total thickness). 210 μm, composition ratio white PP: PO1: white PP = 1: 1: 1) sheet is produced from a molding apparatus comprising an inner / outer layer extruder, an intermediate layer extruder, a feed block, a T-die, a cooling roll, and a sheet take-up device. (Deoxygenating sheet 1).
A test piece (30 × 30 mm) prepared from this sheet is placed in a gas-impermeable cup (with an internal volume of 85 ml) together with 1 ml of distilled water and heated and sealed with a heat-sealing lid made of a gas-impermeable aluminum foil laminate film. A storage test was conducted at a temperature of 50 ° C.
After storage for a certain period, the hydrogen concentration in the container was measured to determine the amount of hydrogen generated in the sheet, and the appearance of the sheet piece was observed.
The observation point was to observe whether the surface was uneven or not, whether or not the layer containing the oxygen absorbent was locally swollen, and whether or not the joint portion was peeled off between the sheets of the multilayer sheet.
As a result, as shown in Table 1, foaming due to hydrogen generation during pellet production was suppressed, and there was no change in sheet appearance.
[0019]
<Comparative Example 1>
A sheet was formed in exactly the same manner as in Example 1 except that calcium hydroxide was changed to sodium phosphate (Comparative Sheet 1).
About evaluation, it carried out similarly to Example 1. FIG.
As a result, as shown in Table 1, a change in sheet appearance occurred.
[0020]
<Comparative example 2>
A sheet was formed in exactly the same manner as in Example 1 except that no calcium hydroxide was added (Comparative Sheet 2).
About evaluation, it carried out similarly to Example 1. FIG.
As a result, as shown in Table 1, pellet foaming occurred.
[0021]
[Table 1]
[0022]
【Effect of the invention】
The deoxidizing container according to the present invention is a thermoplastic resin in which an oxygen absorbent composed of 0.1 to 20 parts by mass of sodium chloride and 0.05 to 2 parts by mass of calcium hydroxide is blended with 100 parts by mass of iron powder. It is presumed that the concentration of moisture in the deoxygenating film or sheet does not occur, because the deoxygenating film or sheet formed from is at least part of the container structure , An excellent effect is obtained that the peeling of the laminate can be prevented and at the same time the generation of hydrogen can be prevented.

Claims (2)

A deoxygenating film or sheet formed from a thermoplastic resin in which an oxygen absorbent comprising 0.1 to 20 parts by mass of sodium chloride and 0.05 to 2 parts by mass of calcium hydroxide is added to 100 parts by mass of iron powder. To be at least part of the container configuration
A deoxygenating container characterized by. The blending amount of the oxygen absorbent is
The oxygen-absorbing container according to claim 1, wherein the oxygen absorbent is 5 to 75 parts by mass per 100 parts by mass of the thermoplastic resin.