JP2003191230A - Production method of oxygen absorptive resin composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide the production method of an oxygen absorptive resin constituent capable of equally distributing an oxygen absorption material in synthetic resin. <P>SOLUTION: The oxygen absorptive resin constituent is produced by adding and kneading an oxygen absorbent that consists of an adsorbent absorbed the oxygen absorption material to melted thermoplastic resin. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing an oxygen-absorbing resin composition.

[0002]

2. Description of the Related Art Conventionally, in the packaging of foods and the like, oxygen present inside the packaging has been a problem. Due to this oxygen, deterioration of food (decomposition, etc.) due to oxidation, growth of microorganisms, and the like occur particularly in foods, and means for removing oxygen is taken to prevent these.

For example, the removal of oxygen in the package can be performed by enclosing a deoxidizer in the package, or by giving the package itself an oxygen absorbing function. In order to impart an oxygen absorbing function to the package itself,
There is a method of using an oxygen-absorbing resin composition produced by mixing an oxygen-absorbing substance and a resin. That is, using a sheet or film made from this oxygen-absorbing resin composition on the surface in contact with the contents of the package, while removing oxygen inside the package, absorb oxygen from the outside in the layer,
It is shut off.

As a method for producing the above oxygen-absorbing resin composition, there is, for example, the method described in JP-A-6-262068. The above-mentioned publication discloses a method for producing an oxygen-absorbing resin composition in which fats and oils which are oxygen-absorbing substances are adsorbed by an adsorbent and then kneaded with a synthetic resin.

[0005]

However, when an oxygen-absorbing resin composition is produced according to the production method of the above-mentioned publication as shown in Comparative Example 1 described later, the adsorbent having an oxygen-absorbing substance adsorbed thereon is used as the synthetic resin. It was difficult to disperse them uniformly. This is because in the above method, in order to uniformly disperse the adsorbent having adsorbed the oxygen absorbing substance in the resin, it is necessary to perform kneading for a long time, but deactivation of the oxygen absorbing substance during kneading. It is considered that this is because the kneading time must be shorter than the time required to uniformly disperse the adsorbent in order to prevent the above. As described above, when the oxygen absorbing substance is not uniformly dispersed in the resin composition, the oxygen absorbing function of the oxygen absorbing resin composition cannot be sufficiently exhibited.

The present invention has been made in view of the above conventional problems, and an object thereof is a method for producing an oxygen-absorbing resin composition by uniformly dispersing an oxygen-absorbing substance in a thermoplastic resin. Another object of the present invention is to provide a method capable of effectively preventing deactivation of an oxygen absorbing substance in the dispersion process.

[0007]

In order to solve the above-mentioned problems, the method for producing an oxygen-absorbing resin composition according to the present invention is an oxygen comprising an adsorbent in which an oxygen-absorbing substance is adsorbed on a molten thermoplastic resin. It is characterized by adding an absorbent and kneading.

According to the above method, after melting the thermoplastic resin, an oxygen absorbent consisting of an adsorbent having an oxygen absorbing substance adsorbed therein is added and kneaded. Therefore, this oxygen absorbent is mixed with the above thermoplastic resin. It can be evenly dispersed therein. Thereby, the oxygen absorbing substance contained in the oxygen absorbing agent can be uniformly dispersed in the thermoplastic resin. At this time, since the fluidity of the thermoplastic resin is high because the thermoplastic resin is melted in advance, as compared with the case where the unmelted thermoplastic resin and the oxygen absorber are mixed and kneaded, The oxygen absorbent can be uniformly dispersed in the thermoplastic resin by kneading for a short time. Therefore, it is possible to shorten the heating time until the oxygen absorbent is uniformly dispersed in the resin. As a result, it is possible to suppress the deactivation of the oxygen absorbent contained in the oxygen absorbent during the dispersion process. Thereby, as compared with the conventional method of adding an oxygen absorber to an unmelted thermoplastic resin and kneading, an oxygen-absorbing resin composition which is excellent in oxygen-absorbing performance and can give a molded article having a good appearance is provided. can do.

Further, in order to solve the above-mentioned problems, the method for producing an oxygen-absorbing resin composition of the present invention comprises an oxygen absorbent comprising an adsorbent having an oxygen-absorbing substance adsorbed, an oxidation catalyst and / or an oxidation initiator. It is characterized in that a mixture obtained by mixing and is added to a molten thermoplastic resin and kneaded.

According to the above method, after melting the thermoplastic resin, an oxygen absorbent composed of an adsorbent in which an oxygen absorbing substance is adsorbed is added and kneaded. Therefore, this oxygen absorbent is mixed with the above thermoplastic resin. It can be evenly dispersed therein. Thereby, the oxygen absorbing substance contained in the oxygen absorbing agent can be uniformly dispersed in the thermoplastic resin. At this time, since the fluidity of the thermoplastic resin is high because the thermoplastic resin is melted in advance, as compared with the case where the unmelted thermoplastic resin and the oxygen absorber are mixed and kneaded, The oxygen absorbent can be uniformly dispersed in the thermoplastic resin by kneading for a short time. Therefore, it is possible to shorten the heating time until the oxygen absorbent is uniformly dispersed in the resin. As a result, it is possible to suppress the deactivation of the oxygen absorbent contained in the oxygen absorbent during the dispersion process. Thereby, as compared with the conventional method of adding an oxygen absorber to an unmelted thermoplastic resin and kneading, an oxygen-absorbing resin composition which is excellent in oxygen-absorbing performance and can give a molded article having a good appearance is provided. can do. Also,
Since an oxidation catalyst and / or an oxidation initiator is added,
The oxygen absorption function can be further improved.

In the following description, unless otherwise specified, "oxygen absorbent" means "oxygen absorbent composed of an adsorbent in which an oxygen absorbent is adsorbed".

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Regarding one embodiment of the present invention,
This will be described below. The present invention is not limited to this.

First, the oxygen adsorbing resin composition produced by the method for producing an oxygen adsorbing resin composition according to the present invention will be described. The oxygen adsorbing resin composition according to the present invention,
At least, an oxygen absorbent is added to the thermoplastic resin, and the dispersibility of the oxygen absorbent is greatly improved as compared with the oxygen absorbent resin composition prepared by the conventional method.

The thermoplastic resin is not particularly limited, but one having a high affinity with the oxygen absorbing substance and the oxygen absorbing agent is preferable, and a polyolefin resin is particularly preferable. Further, the oxygen-absorbing resin composition is formed into a film or a sheet, and is used to further form a packaging container such as a bag. Therefore, a polyolefin resin having excellent heat-sealing property, such as polyethylene or ethylene It is preferable to use a polymer or polypropylene.

The oxygen-absorbing substance absorbs oxygen by itself being autoxidized. The oxygen absorbing substance is not particularly limited, but a substance that is liquid at room temperature (25 ° C.) is preferably used. Examples of preferable oxygen absorbing substances include unsaturated compounds, of which unsaturated fatty acids or esters thereof are preferably used. More specifically, monoenoic acids such as oleic acid; dienoic acids such as linoleic acid; trienoic acids such as α-linolenic acid (usually simply referred to as linolenic acid) and γ-linolenic acid; eicosapentaenoic acid, docosapentaene. And polyunsaturated fatty acids such as acid and docosahexaenoic acid; esters of these unsaturated fatty acids; and the like. These unsaturated fatty acids may be natural products or synthetic products. Further, these unsaturated fatty acids may be used alone or in combination of two or more.

Further, various natural oils and fats containing a large amount of the above unsaturated fatty acids are also preferably used. Specifically, for example, soybean oil, rapeseed oil, linseed oil, sunflower oil, evening primrose seed oil, cottonseed oil, camellia oil, safflower oil, and other seed oils; olive oil and other fruit oils; rice oil, corn Germ oil such as oil; fish oil; and the like.

Among the above-mentioned natural oils and fats, olive oil and camellia oil are listed as those containing a large amount of oleic acid.
Flaxseed oil can be used as a high content of α-linolenic acid, evening primrose seed oil can be used as a high content of γ-linolenic acid, and soybean oil, corn oil, cottonseed oil, safflower oil can be used as a high content of linoleic acid. Sunflower oil can be mentioned, and fish oil can be mentioned as one containing a large amount of eicosapentaenoic acid / docosapentaenoic acid / docosahexaenoic acid.

The adsorbent adsorbs (supports) the oxygen absorbing substance. Further, it is preferable that the adsorbent further has an adsorbing ability to adsorb an odor component generated when the oxygen absorbing substance is oxidized.

The material of the adsorbent is not particularly limited, but zeolites such as natural zeolite and synthetic zeolite: oxides such as silica gel and activated alumina;
Silica compounds such as aluminum silicate and magnesium silicate; activated carbon; activated clay; and the like can be preferably used. These may be used alone or in combination of two or more.

The shape of the adsorbent is not particularly limited, but the average particle diameter of the adsorbent is preferably 100 μm or less in consideration of dispersibility in the thermoplastic resin. It is preferably 50 μm or less, and particularly preferably 20 μm or less.

An oxidation catalyst and / or an oxidation initiator may be added to the oxygen absorbing resin composition.

The oxidation catalyst and / or the oxidation initiator promotes the oxidation of the oxygen absorbing substance. For example, examples of the above-mentioned oxidation catalyst include metal catalysts composed of transition metal compounds, and more specifically, cobalt,
Examples thereof include organic acid salts of metals such as manganese, iron, copper, nickel, titanium, vanadium and chromium. Examples of the organic acid include stearic acid, acetylacetonic acid, dimethylcarbamic acid, naphthenic acid and the like. Examples of the above-mentioned oxidation initiator include azo compounds and organic peroxides.

Here, a method for producing the oxygen absorbing resin composition will be described. The oxygen-absorbing resin composition,
It is manufactured by adding an oxygen absorbent composed of an absorbent in which an oxygen absorbing substance is adsorbed to a molten thermoplastic resin and kneading the mixture.

According to the above method, since the thermoplastic resin is melted and then the oxygen absorbent is added and kneaded, the oxygen absorbent can be uniformly dispersed in the thermoplastic resin. Thereby, the oxygen absorbing substance contained in the oxygen absorbing agent can be uniformly dispersed in the thermoplastic resin. At this time, since the thermoplastic resin is melted in advance, the fluidity of the thermoplastic resin is high. Therefore,
Compared with the case where the unmelted thermoplastic resin and the oxygen absorbent are mixed and kneaded, the oxygen absorbent can be uniformly dispersed in the thermoplastic resin by kneading for a shorter time.
Therefore, it is possible to shorten the heating time until the oxygen absorbent is uniformly dispersed in the resin. As a result, it is possible to suppress the deactivation of the oxygen absorbent contained in the oxygen absorbent during the dispersion process. Thereby, as compared with the conventional method of adding an oxygen absorber to an unmelted thermoplastic resin and kneading, an oxygen-absorbing resin composition which is excellent in oxygen-absorbing performance and can give a molded article having a good appearance is provided. can do.

Further, when adsorbing the oxygen absorbing substance to the adsorbent, an oxidation catalyst and / or an oxidation initiator may be mixed. This makes it possible to further improve the oxygen absorbing function of the oxygen absorbing resin composition produced.

The oxygen-absorbing resin composition can be molded into a film or sheet. Such a film or sheet made of an oxygen-absorbing resin composition,
It can be used by forming it into a bag-shaped container or further into a cup-shaped container formed by vacuum forming or the like. Alternatively, it may be directly molded into a container shape by a method such as blow molding or injection molding.

The oxygen-absorbing resin composition can be used in combination with other films or sheets, if necessary. For example, when molded as a container, an oxygen barrier layer (oxygen barrier resin layer, metal foil layer, metal oxide layer, etc.) that prevents penetration and entry of oxygen from the outside.
Can be combined with. It may also be combined with a sealant layer so as not to come into direct contact with the inside. This sealant layer is preferably permeable to oxygen so that the layer containing the oxygen-absorbing resin composition can absorb the internal oxygen. Further, the oxygen barrier layer or metal layer and the sealant layer may be used in combination.

As described above, the oxygen-absorbing resin composition can be used as an oxygen-absorbing layer for containers and the like.

Further, the method for producing an oxygen-absorbing resin composition of the present invention comprises the steps of adsorbing an oxygen-absorbing substance to an adsorbent to produce an oxygen-absorbing agent, and melting a thermoplastic resin.
It can also be expressed as a method for producing an oxygen-absorbing resin composition, which includes the step of adding the oxygen absorber to the molten thermoplastic resin and kneading the mixture.

As a result, the oxygen absorbing substance can be uniformly dispersed in the thermoplastic resin, and the oxygen absorbing resin composition having an excellent oxygen absorbing function can be produced.

When an oxidation catalyst and / or an oxidation initiator is further added, in the step of producing the oxygen absorbent, the oxygen absorption substance is adsorbed on the adsorbent, and the oxidation catalyst and / or the oxidation initiator is added. By doing so, an oxygen absorbent may be produced. Thereby, the oxygen absorption function can be further improved.

As the manufacturing apparatus used in the manufacturing method according to the present invention, a conventionally known apparatus can be used and is not particularly limited. Further, various conditions at the time of manufacturing are also appropriately set according to the types of the thermoplastic resin and the oxygen absorbing substance, and are not particularly limited.

[0033]

EXAMPLES The method for producing the oxygen-absorbing resin composition of the present invention will be described below with reference to examples.

[Example 1] In this example, linseed oil (manufactured by Nakarai Tex) was used as an oxygen absorbing substance, and Godball (registered trademark) E-16C (Suzuki Yushi Kogyo porous silica, particle diameter) was used as an adsorbent. 0.5 μm to 18 μm), cobalt stearate (manufactured by Soegawa Rikagaku) was used as the oxidation catalyst, and block polypropylene (manufactured by Sumitomo Chemical) was used as the thermoplastic resin.

First, god balls were added little by little to 2 L of flaxseed oil and added until they became lumpy. Then add god balls until the total amount of god balls reaches 3 kg,
Stir with a 20 L super mixer. Stirring speed 1000
After stirring at rpm for 30 minutes at a temperature of 30 ° C., 40 g of cobalt stearate was added and further mixed with a super mixer (1
The mixture was stirred at 000 rpm, 30 ° C) for 5 minutes. Thereby, an oxygen-absorbing powder (oxygen absorber) was produced.

Next, only block polypropylene was melt-kneaded by an extruder. The cylinder temperature in the extruder at this time was 220 ° C. Then, to the molten block polypropylene, add oxygen-absorbing powder,
Further kneading was carried out using an extruder. This produced the oxygen-absorbing resin composition. This oxygen-absorbing resin composition was produced in a weight ratio of block polypropylene: oxygen-absorbing powder = 75: 25.

Then, a film was produced using the oxygen-absorbing resin composition at a molding temperature of 240 ° C. This film had a thickness of 100 μm. As a result, it was possible to manufacture an oxygen-absorbing film having a good appearance and no lumps. Moreover, this oxygen absorption film was able to fully exhibit the oxygen absorption function.

[Comparative Example 1] In this comparative example, the thermoplastic resin and the oxygen-absorbing powder (oxygen absorbent) were mixed without kneading the thermoplastic resin in advance, and then kneaded to obtain the oxygen-absorbing property. It is an example of manufacturing a resin composition.

First, the pelletized block polypropylene and the oxygen-absorbing powder prepared in Example 1 were mixed. Then, this mixture was kneaded with an extruder. The kneading time at this time was almost the same as in Example 1 above. This produced the oxygen-absorbing resin composition. This oxygen-absorbing resin composition was produced in the same manner as in Example 1 with a weight ratio of block polypropylene: oxygen-absorbing powder = 75: 25.

Then, a film was produced using the oxygen-absorbing resin composition at a molding temperature of 240 ° C. This film had a thickness of 100 μm. As a result, an oxygen-absorbing film with a lot of lumps and a bad appearance was produced. Also,
This oxygen absorbing film did not exhibit a sufficient oxygen absorbing function.

As shown in Comparative Example 1, it was found that the oxygen absorbing powder could not be uniformly dispersed in the thermoplastic resin at the same kneading time as in Example 1. From this, it was inferred that the kneading time had to be extended in order to mix the block polypropylene and the oxygen-absorbing powder and then knead the mixture to produce the oxygen-absorbing resin composition.
However, extending the kneading time leads to heating the oxygen-absorbing substance for a long time, and the oxygen-absorbing substance is oxidized and deteriorates, so that the oxygen-absorbing function of the produced oxygen-absorbing resin composition decreases. The problem arises.

[0042]

As described above, the method for producing an oxygen-absorbing resin composition of the present invention is kneaded by adding an oxygen absorbent, which is an adsorbent in which an oxygen-absorbing substance is adsorbed, to a molten thermoplastic resin. This is the configuration.

According to the above method, since the thermoplastic resin is melted and then the oxygen absorbent is added and kneaded, the oxygen absorbent can be uniformly dispersed in the thermoplastic resin, and the thermoplastic resin can be dispersed. The oxygen absorbing substance contained in the oxygen absorbing agent can be uniformly dispersed in the resin. At this time, the kneading time can be shortened compared to the conventional method, and the oxygen absorbent can be uniformly dispersed in the thermoplastic resin in a relatively short time. The effect of being able to shorten the time for heating the oxygen absorbing material and suppressing the deterioration (oxidation) of the oxygen absorbing material due to heat is also exhibited. That is, it is possible to provide an oxygen-absorbing resin composition that can sufficiently exhibit the oxygen-absorbing function.

Further, in the method for producing the oxygen-absorbing resin composition of the present invention, as described above, the oxygen absorbent composed of the adsorbent in which the oxygen-absorbing substance is adsorbed, and the oxidation catalyst and / or the oxidation initiator are mixed. The mixture is added to the molten thermoplastic resin and kneaded.

According to the above method, since the thermoplastic resin is melted and then the oxygen absorbent is added and kneaded, the oxygen absorbent can be uniformly dispersed in the thermoplastic resin and the thermoplastic resin The oxygen absorbing substance contained in the oxygen absorbing agent can be uniformly dispersed in the resin. At this time, the kneading time can be shortened compared to the conventional method, and the oxygen absorbent can be uniformly dispersed in the thermoplastic resin in a relatively short time. The effect of being able to shorten the time for heating the oxygen absorbing material and suppressing the deterioration (oxidation) of the oxygen absorbing material due to heat is also exhibited. That is, it is possible to provide an oxygen-absorbing resin composition that can sufficiently exhibit the oxygen-absorbing function. Furthermore, since an oxidation catalyst is added, the effect of exhibiting a better oxygen absorbing function is also obtained.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C08L 91/00 C08L 91/00 101/00 101/00 // B29K 101: 12 B29K 101: 12 F term ( (Reference) 4D020 AA02 BA19 BB01 BB07 CA01 4F201 AA11 AB01 AB28 AC01 AG01 AG03 AG07 AR11 BA01 BC01 BC12 BC33 BC37 BK01 BK02 BK13 BK15 BK73 BQ04 4J002 AA011 AE002 BB021 020 BB021 207

Claims (2)

[Claims] 1. A method for producing an oxygen-absorbing resin composition, which comprises adding an oxygen absorbent composed of an adsorbent in which an oxygen-absorbing substance is adsorbed to a molten thermoplastic resin and kneading the mixture. 2. A mixture of an oxygen absorbent composed of an adsorbent having an oxygen absorbing substance and an oxidation catalyst and / or an oxidation initiator is added to a molten thermoplastic resin and kneaded. A method for producing an oxygen-absorbing resin composition.