JP2011131578A - Oxygen absorbing multilayer object - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a means for solving the following problems: a conventional oxygen absorbing multilayer object is bad in resin processability, restricted in application uses, and inferior in oxygen absorbing performance and interlaminar strength. <P>SOLUTION: In an oxygen absorbing multilayer object wherein at least four layers of a sealant layer made of a polyolefin resin, an oxygen absorbing layer containing a polyolefin resin, a transition metal catalyst, and a polyamide resin, an intermediate layer made of a polyolefin resin, and a gas-barrier layer made of a gas-barrier substance are piled up in turn, the polyamide resin is obtained by the polycondensation of an aromatic diamine and a dicarboxylic acid and has a terminal amino group concentration of 30 μeq/g or below, and the total content of the transition metal catalyst in the oxygen absorbing layer and the polyamide resin is 15-60 wt.% of the total amount of the oxygen absorbing resin layer. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an oxygen-absorbing multilayer body that exhibits excellent oxygen-absorbing performance and is free from strength reduction and odor generation due to oxidative degradation of resin.

  Conventionally, containers such as metal cans, glass bottles, and various plastic packages have been known as packaging containers, but quality deterioration due to oxygen in the packaging containers has been a problem. For this reason, in recent years, as one of the deoxygenation packaging technologies, a container is constituted by a multilayer material in which an oxygen absorption layer composed of an oxygen absorption resin composition in which an iron-based oxygen absorber is blended with a thermoplastic resin is provided. Development of packaging containers in which the gas barrier property is improved and the container itself is provided with an oxygen absorbing function has been performed. For example, an oxygen-absorbing multilayer film is a thermoplastic in which an oxygen absorbent is dispersed between a conventional gas-barrier multilayer film in which a heat seal layer and a gas barrier layer are laminated, and optionally through an intermediate layer made of a thermoplastic resin. It is used as a resin layer with an oxygen absorption layer added to the outside to prevent oxygen permeation, and to absorb oxygen in the container. It is manufactured using a method (see Patent Document 1).

  However, those using oxygen absorbers such as iron powder are detected by metal detectors used for detecting foreign substances such as food, and the internal visibility is insufficient due to the problem of opacity. There was a problem that it cannot be used for beverages such as alcohol whose flavor is impaired. In addition, since the oxidation reaction of iron powder is used, the effect of oxygen absorption can be exhibited only when the material to be preserved is a high moisture type.

  On the other hand, in a composition composed of a polymer and having an oxygen scavenging property, a resin composition comprising a polyamide, particularly a xylylene group-containing polyamide and a transition metal, is known as an oxidizable organic component, and a resin composition having an oxygen scavenging function or There are also examples of oxygen absorbents obtained by molding the resin composition, packaging materials, and multilayer laminated films for packaging (see Patent Documents 2 to 6).

  However, a resin composition containing a transition metal catalyst and oxidizing a polyamide resin or the like to develop an oxygen absorbing function oxidizes the xylylene group-containing polyamide resin, resulting in a decrease in strength due to oxidative degradation of the resin, and the packaging container itself There is a problem that the strength of the glass is reduced.

In addition, when a resin composition comprising a xylylene group-containing polyamide and a transition metal is used as a multilayer laminated film, the transition metal is liberated on the surface of the oxygen absorption layer, resulting in a decrease in interlayer strength between the gas barrier layer and the oxygen absorption layer. There is also a problem that the strength of the packaging container itself is lowered.

  Furthermore, there is an example of MXD6, which is a polyamide obtained by polycondensation of metaxylylenediamine and adipic acid, as an example showing an oxidation reaction with a polyamide resin and a transition metal catalyst. In a system in which transition metal is mixed with MXD6, For use as an oxygen-absorbing resin composition and preserving the material to be stored well, the oxygen-absorbing ability may be low. In addition, a system in which transition metal is mixed with MXD6 usually uses a blend of a polyester resin such as polyethylene terephthalate (hereinafter referred to as PET) or a resin having a relatively high melting point such as nylon 6.

Japanese Patent Laid-Open No. 9-234832 Japanese Patent Laid-Open No. 5-140555 JP 2001-252560 A JP 2003-341747 A JP 2005-119893 A JP 2001-179090 A

  An object of the present invention is to provide an oxygen-absorbing multilayer body that solves the above-mentioned problems, is excellent in oxygen absorption performance, resin strength, and resin processability, and has improved interlayer strength between an oxygen-absorbing monk and a gas barrier layer.

  The present inventors blend specific polyamides, transition metals and polyolefin resins in specific proportions, so that the oxygen absorption performance is excellent, the resin strength after storage is maintained, the workability is excellent, and the intermediate layer Thus, it was found that an oxygen-absorbing multilayer body having improved interlayer strength between the oxygen-absorbing layer and the gas barrier layer was obtained.

  That is, the present invention includes at least four layers in this order: a sealant layer made of a polyolefin resin, an oxygen absorption layer containing a polyolefin resin, a transition metal catalyst and a polyamide resin, an intermediate layer made of a polyolefin resin, and a gas barrier layer made of a gas barrier material. A laminated oxygen-absorbing multilayer body, wherein the polyamide resin is a polyamide resin having a terminal amino group concentration of 30 μeq / g or less obtained by polycondensation of an aromatic diamine and a dicarboxylic acid, and the oxygen-absorbing layer The oxygen-absorbing multilayer body is characterized in that the total content of the transition metal catalyst and the polyamide resin is 15 to 60% by weight based on the total amount of the oxygen-absorbing resin layer.

  According to the present invention, it is possible to provide an oxygen-absorbing multilayer body that has high oxygen absorption performance, hardly undergoes strength deterioration due to oxidation of the polyamide resin, and has improved the laminate strength of the multilayer body by the intermediate layer.

  The oxygen-absorbing multilayer body of the present invention is obtained by laminating at least four layers of a sealant layer, an oxygen-absorbing layer, an intermediate layer, and a gas barrier layer in this order, and is obtained by polycondensation of an aromatic diamine and a dicarboxylic acid on the oxygen-absorbing layer. The oxygen-absorbing multilayer body contains a polyamide resin having a terminal amino group concentration of 30 μeq / g or less (hereinafter, the polyamide resin is particularly referred to as “polyamide resin A”), a transition metal catalyst, and a polyolefin resin. Details of each layer and each composition of these oxygen-absorbing multilayer bodies will be described.

  The oxygen absorption performance of the oxygen absorption layer is considered to be better when there is more polyamide resin having oxygen absorption ability, but surprisingly, polyamide resin A, transition metal and polyolefin resin are mixed and blended at a certain ratio. In particular, it was found to show a high oxygen absorption capacity.

  The polyamide resin A in the present invention is obtained by polycondensation of an aromatic diamine and a dicarboxylic acid. The polycondensation of the aromatic diamine and the dicarboxylic acid can proceed by melt polymerization for melting the aromatic diamine and dicarboxylic acid, solid phase polymerization for heating the polyamide resin pellets, or the like under reduced pressure.

  Examples of the aromatic diamine in obtaining the polyamide resin A include orthoxylylenediamine, paraxylylenediamine, and metaxylylenediamine, but paraxylylenediamine, metaxylylenediamine, or these from the viewpoint of oxygen absorption performance. A mixture is preferably used, and metaxylylenediamine is particularly preferably used. In addition, various aliphatic diamines and aromatic diamines may be incorporated as copolymerization components as long as the performance is not affected.

  Examples of the dicarboxylic acid for obtaining the polyamide resin A include adipic acid, azelaic acid, sebacic acid, dodecanoic acid, isophthalic acid, terephthalic acid, and malonic acid. Among these, from the viewpoint of oxygen absorption performance, adipic acid, sebacic acid, isophthalic acid or a mixture thereof is preferable, and a mixture of adipic acid and sebacic acid or a mixture of adipic acid and isophthalic acid is particularly preferable. The molar ratio in the case of using a mixture of adipic acid and sebacic acid is preferably sebacic acid: adipic acid = 0.3-0.7: 0.7-0.3, and 0.4-0.6: 0.6 -0.4 is particularly preferred. Further, when using a mixture of adipic acid and isophthalic acid, adipic acid: isophthalic acid is preferably 0.7 to 0.97: 0.3 to 0.03, and 0.8 to 0.95: 0.2 to 0 .05 is particularly preferred. In addition, various aliphatic dicarboxylic acids and aromatic dicarboxylic acids may be incorporated as copolymerization components as long as the performance is not affected.

  The polyamide resin A in the present invention is a polyamide resin having a terminal amino group concentration of 30 μeq / g or less obtained by polycondensation of at least an aromatic diamine and a dicarboxylic acid, but has a terminal amino group concentration of 25 μeq / g or less. And oxygen absorption performance are improved, and it is more preferably 20 μeq / g or less because oxygen absorption performance is further improved. Thus, the oxygen absorption performance tends to improve as the terminal amino group concentration decreases, and it is preferable to reduce the concentration as much as possible. However, in consideration of economic rationality, the lower limit is 5 μeq / g or more. It is preferable to do. If the terminal amino group concentration is higher than 30 μeq / g, good oxygen absorption performance cannot be obtained.

In order to reduce the terminal amino group concentration of the polyamide resin to 30 μeq / g or less,
1) Method for carrying out polycondensation by adjusting the molar ratio of aromatic diamine and dicarboxylic acid 2) Method for reacting polyamide resin with carboxylic acid to seal the terminal amino group 3) Method for solid-phase polymerization of polyamide resin These methods are preferably carried out, and these methods can be carried out alone or in combination. In particular, it is preferable to combine the methods 1), 3), 2) and 3) because a polyamide resin having better oxygen absorption performance and moldability during film production can be obtained. Hereinafter, these methods will be described.

  1) In the method of carrying out polycondensation by adjusting the molar ratio of aromatic diamine and dicarboxylic acid, dicarboxylic acid is used excessively with respect to aromatic diamine. Specifically, aromatic diamine and dicarboxylic acid are used. The molar ratio (aromatic diamine / dicarboxylic acid) is preferably 0.985 to 0.997, particularly preferably 0.988 to 0.995. If the molar ratio is less than 0.985, it is difficult to increase the degree of polymerization of the polyamide resin.

  2) In the method of reacting the polyamide resin with carboxylic acid to seal the terminal amino group, the terminal amino group concentration of the polyamide resin is reacted with the carboxylic acid to adjust the terminal amino group concentration. The carboxylic acid to be used is not particularly limited, but a carboxylic anhydride is preferable, and specifically, phthalic anhydride, maleic anhydride, benzoic anhydride, glutaric anhydride, itaconic anhydride, citraconic anhydride, acetic anhydride, anhydrous Examples include butyric acid, isobutyric anhydride, trimellitic anhydride, pyromellitic anhydride, and the like. The polyamide resin and the carboxylic acid can be reacted by, for example, a method of adding at the time of melt polymerization or a method of adding a carboxylic acid to the polyamide resin obtained by melt polymerization and then melt-kneading the polyamide resin. In order to increase the degree of polymerization, melt kneading is preferred.

  3) In the method of solid-phase polymerization of polyamide resin, the terminal amino group concentration is adjusted by further subjecting the polyamide resin obtained by melt polymerization to a solid-phase polymerization reaction. Solid phase polymerization proceeds by heating polyamide resin pellets under reduced pressure. The pressure during the solid phase polymerization is preferably 100 torr or less, and more preferably 30 torr or less. Further, the temperature at the time of solid phase polymerization needs to be 130 ° C. or higher, more preferably 150 ° C. or higher, and preferably 10 ° C. or higher, more preferably 15 ° C. or lower than the melting point of the polyamide resin. The solid state polymerization time is preferably 3 hours or more. By performing solid phase polymerization, the terminal amino group concentration of the polyamide resin is decreased, the molecular weight is increased, and the viscosity can be adjusted.

  As the polyamide resin A of the present invention, those having low crystallinity are preferably used. Specifically, those having low crystallinity with a half-crystallization time of 150 seconds or more, or those having no melting point peak when measuring the melting point by DSC are preferable. When the half crystallization time of the polyamide resin A is 150 seconds or more, higher oxygen absorption performance can be obtained.

  Further, the polyamide resin A preferably has a low melting point and glass transition temperature (hereinafter referred to as Tg) in consideration of processability and oxygen absorption performance with a polyolefin resin. The melting point of the polyamide resin A is preferably 200 ° C. or lower, more preferably 190 ° C. or lower or a resin having no melting point. Tg is preferably 90 ° C. or lower, and particularly preferably 80 ° C. or lower.

The oxygen permeability coefficient of the polyamide resin A is preferably 0.2 to 1.5 cc · mm / (m ² · day · atm) (23 ° C. · 60% RH), and 0.3 to 1.0 cc · mm / (m ² · day · atm) (23 ° C. · 60% RH) is more preferable. When the oxygen permeability coefficient is 0.2 to 1.5 cc · mm / (m ² · day · atm) (23 ° C. · 60% RH), when the polyamide resin A and the polyolefin resin are blended, higher oxygen absorption performance is obtained. can get.

  When the polyamide resin A and the polyolefin resin are mixed, considering the processability, the melt flow rate (hereinafter referred to as MFR) of the polyamide resin A is 200 ° C., 3 to 20 g / 10 minutes, 240 ° C., 4 Those having ˜25 g / 10 min are preferably used. In this case, when the resin is processed at a temperature where the difference between the MFR of the polyolefin resin and the MFR of the polyamide resin A is ± 20 g / 10 minutes, preferably ± 10 g / 10 minutes, the kneaded state becomes good, and a film or sheet is obtained. In this case, a processed product having no problem in appearance can be obtained. The MFR of the polyamide resin A can be adjusted by adjusting the molecular weight, for example. Examples of a method for adjusting the molecular weight include a method of adding a phosphorus compound as a polymerization accelerator and a method of solid-phase polymerization after melt polymerization of the polyamide resin A. In addition, MFR as used in this specification is MFR of the said resin measured on the conditions of the load of 2160g in specific temperature using the apparatus based on JISK7210, unless there is particular notice, "g / 10. Expressed with the measured temperature in units of minutes.

  The polyamide resin A obtained by polycondensation of an aromatic diamine and a dicarboxylic acid is preferably synthesized by a method that undergoes two steps of solid phase polymerization after melt polymerization. The number average molecular weight of the polyamide resin A is preferably 18000 to 27000, particularly preferably 20000 to 26000.

The polyolefin resin used for the oxygen absorbing layer in the present invention is a high density polyethylene, a medium density polyethylene, a low density polyethylene, a linear low density polyethylene, an ultra low density polyethylene, various polyethylenes such as a metallocene catalyst polyethylene, polystyrene, etc. Polypropylenes such as polymethylpentene, propylene homopolymer, propylene-ethylene block copolymer, propylene-ethylene random copolymer can be used alone or in combination. Among these polyolefin resins, from the viewpoint of oxygen absorption performance, the oxygen permeability coefficient is preferably 80 to 200 cc · mm / (m ² · day · atm) (23 ° C. · 60% RH). When the polyolefin resin is used, good oxygen absorption performance can be obtained. Due to oxygen absorption performance and film processability, polyolefin resins include high-density polyethylene, medium-density polyethylene, low-density polyethylene, linear low-density polyethylene, various polyethylenes such as polyethylene using a metallocene catalyst, and propylene-ethylene block copolymers. Various polypropylenes such as propylene-ethylene random copolymer are particularly preferably used. These polyolefin resins include ethylene-vinyl acetate copolymer, ethylene-methyl acrylate copolymer, ethylene-ethyl acrylate copolymer, ethylene-acrylic acid copolymer, ethylene-methacrylic acid copolymer, if necessary. A polymer, an ethylene-methyl methacrylate copolymer, or a thermoplastic elastomer may be added.

  In consideration of the miscibility with the polyamide resin A, it is particularly preferable to add a maleic anhydride-modified polyolefin resin. The addition amount of the maleic anhydride-modified product is preferably 1 to 30 wt%, particularly preferably 3 to 15 wt% with respect to the polyolefin resin.

  Further, the polyolefin resin of the present invention includes coloring pigments such as titanium oxide, additives such as antioxidants, slip agents, antistatic agents, stabilizers, fillers such as calcium carbonate, clay, mica, silica, and deodorants. An agent or the like may be added. In particular, it is preferable to add an antioxidant in order to recycle and reprocess offcuts generated during production.

  Examples of the transition metal catalyst used in the present invention include compounds of a first transition element such as Fe, Mn, Co, and Cu. Further, transition metal organic acid salts, chlorides, phosphates, phosphites, hypophosphites, nitrates and the like alone or a mixture thereof can be cited as examples of transition metal catalysts. Examples of the organic acid include salts of C2-C22 aliphatic alkyl acids such as acetic acid, propionic acid, octanoic acid, lauric acid, stearic acid, or malonic acid, succinic acid, adipic acid, sebacic acid, hexahydrophthalic acid A salt of a dibasic acid, a salt of butanetetracarboxylic acid, benzoic acid, toluic acid, o-phthalic acid, isophthalic acid, terephthalic acid, trimesic acid or the like, or a mixture of aromatic carboxylic acid salts alone or in combination. Among the transition metal catalysts, an organic acid salt of Co is preferable from the viewpoint of oxygen absorption, and Co stearate is particularly preferable from the viewpoint of safety and workability.

  The transition metal catalyst is preferably added to the polyamide resin A and then mixed with the polyolefin resin. The transition metal catalyst is preferably added so that the concentration of all transition metals in the catalyst with respect to the polyamide resin A is 10 ppm to 5000 ppm, preferably 50 ppm to 3000 ppm. In this case, compared with the case where the addition amount is out of the above range, the oxygen absorption performance of the polyamide resin A can be improved, and the deterioration of the resin processability due to the decrease in the viscosity can be prevented.

Another method for producing the oxygen-absorbing resin composition of the present invention is preferably a method for producing an oxygen-absorbing resin composition in which a masterbatch containing a polyolefin resin and a transition metal catalyst and a polyamide resin are melt-kneaded.
The transition metal catalyst is kneaded with the polyolefin resin to produce a master batch, and then melt mixed with the polyamide resin A to obtain an oxygen-absorbing resin composition. The transition metal catalyst is added so that the concentration of all transition metals in the catalyst with respect to the polyolefin resin is preferably 200 ppm to 5000 ppm, more preferably 300 ppm to 3000 ppm. In this case, the oxygen absorption performance of the polyamide resin A can be enhanced as compared with the case where the addition amount is out of the above range. Moreover, when it exceeds 5000 ppm, it may become difficult to manufacture a masterbatch, and it may become impossible to manufacture what has a uniform property. If a transition metal catalyst is added to the polyamide resin A, the resin processability is deteriorated due to a decrease in the viscosity of the polyamide resin A.

The total content of the transition metal catalyst and the polyamide resin A in the oxygen absorbing layer is 15 to 60% by weight, preferably 17 to 60% by weight, more preferably 20 to 60% by weight, and particularly preferably 25 to 50% by weight. preferable. When the content of the polyamide resin A containing the transition metal catalyst in the oxygen-absorbing resin composition is less than 15% by weight or exceeds 60% by weight, the oxygen-absorbing ability is lowered. On the other hand, if it exceeds 60% by weight, resin degradation due to oxidation of the polyamide resin A occurs, causing problems such as strength reduction.
When the master batch of the present invention and the polyamide resin A are melt-kneaded, the content of the polyamide resin A and the transition metal concentration can be adjusted by simultaneously adding the polyolefin resin.

  You may add a stabilizer etc. to the polyamide resin A obtained by this invention suitably. In particular, phosphorus compounds are preferably used as stabilizers, and specifically, diphosphites are preferable. The phosphorus compound is preferably not more than 200 ppm, particularly preferably not more than 100 ppm because the polyamide resin A is stable and affects the oxygen absorption performance.

  For the sealant layer containing the polyolefin resin, it is preferable to use the same sealant as that used for the oxygen absorbing layer in consideration of compatibility. Gas barrier materials used for the gas barrier layer include various vapor deposition films such as silica, alumina and aluminum, ethylene-vinyl alcohol copolymer, MXD6, polyvinylidene chloride, amine-epoxy curing agent and other gas barrier resins, aluminum foil, etc. A known gas barrier material such as a metal foil can be used.

  The intermediate layer containing the polyolefin resin between the gas barrier layer containing the gas barrier substance and the oxygen absorbing layer in the present invention is similar to the polyolefin resin used for the oxygen absorbing layer in the same manner as the sealant layer in consideration of compatibility. It is preferable to use one. This intermediate layer can prevent a decrease in interlayer strength with the gas barrier layer, which is caused by the transition metal catalyst liberated from the oxygen absorbing layer. The thickness of the intermediate layer is preferably substantially the same as the thickness of the sealant layer from the viewpoint of workability, but is particularly preferably 2 to 50 μm and particularly preferably 5 to 30 μm. In this case, considering variations due to processing, the thickness is the same if the thickness ratio is within ± 10%.

  Although there is no restriction | limiting in particular in the thickness of an oxygen absorption layer, 5-100 micrometers is preferable and 10-50 micrometers is especially preferable. In this case, as compared with the case where the thickness is out of the above range, it is possible to further improve the performance of the oxygen absorbing layer to absorb oxygen and to prevent the workability and economy from being impaired. Further, the thickness of the sealant layer is preferably less because the sealant layer becomes an isolation layer from the oxygen absorbing layer, but is particularly preferably 2 to 50 μm, and particularly preferably 5 to 30 μm. In this case, compared with the case where the thickness is out of the above range, it is possible to increase the rate of absorbing oxygen in the oxygen absorbing layer and to prevent the workability from being impaired. When processing into a film or sheet, considering the workability, the thickness ratio of the sealant layer, the oxygen absorbing layer and the intermediate layer is preferably 1: 0.5: 1 to 1: 3: 1. : 1-1: 2.5: 1 is particularly preferable.

  The obtained oxygen-absorbing multilayer body can be used as an oxygen-absorbing paper container by laminating a paper substrate on the outer layer of the gas barrier layer. The processability of the paper container laminated with the paper base material is preferably 60 μm or less, particularly preferably 50 μm or less, at the inner side of the gas barrier layer. When the internal thickness is larger than that of the gas barrier layer, a problem arises in processability to a container when a paper base material is laminated and formed into a container shape.

  The obtained oxygen-absorbing multilayer body can be prepared as a film, processed into a bag shape and a lid material, and used. The obtained oxygen-absorbing multilayer body can be produced as a sheet and molded into a tray or a cup. Moreover, the obtained bag-shaped container and cup-shaped container can perform a boil process of 80-100 degreeC, a semi-retort, a retort, and a high retort process of 100-135 degreeC. Moreover, it is preferably used for a microwave cooking-compatible pouch that fills a bag-like container with contents such as food, provides an opening, and releases steam from the opening when cooking with a microwave oven. it can.

  Since this oxygen-absorbing multilayer body can absorb oxygen regardless of the presence or absence of moisture in the stored material, it can be used for dry foods such as powder seasonings, powdered coffee, coffee beans, rice, tea, beans, rice crackers, rice crackers, etc. It can be suitably used for health foods such as pharmaceuticals and vitamins. In addition, the oxygen-absorbing multilayer obtained by the present invention can be suitably used for alcoholic beverages and carbonated beverages that cannot be stored due to the presence of iron, unlike conventional oxygen-absorbing multilayers using iron powder.

  Other items to be preserved include rice processing such as polished rice, cooked rice, red rice, and glutinous rice, cooked foods such as soup, stew, and curry, fruit, mutton, pudding, cake, confectionery such as buns, tuna, and fish shellfish Examples include fishery products, processed milk products such as cheese and butter, processed meat products such as meat, salami, sausage and ham, vegetables such as carrots, potatoes, asparagus and shiitake mushrooms, and eggs.

  Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto. In the examples and comparative examples, various physical property values were measured by the following measuring methods and measuring apparatuses.

(Measurement method of Tg)
Tg was measured according to JIS K7122. The measuring apparatus used was “DSC-60” manufactured by Shimadzu Corporation.

(Measuring method of melting point)
The melting point was determined by measuring the DSC melting peak temperature according to ISO11357. The measuring apparatus used was “DSC-60” manufactured by Shimadzu Corporation.

(Measurement method of number average molecular weight)
The number average molecular weight was measured by GPC-LALLS. As a measuring apparatus, “Shodex GPC-2001” manufactured by Showa Denko KK was used.

(Measurement method of MFR)
The MFR of each resin is measured under a load of 2160 g at a specific temperature using an apparatus in accordance with JIS K7210 (“Melt Indexer” manufactured by Toyo Seiki Seisakusho Co., Ltd.), and the value is described together with the temperature. (Unit: “g / 10 min”). In addition, when MFR was measured based on JISK7210, it was described that much.

(Measurement method of oxygen permeability coefficient)
The oxygen transmission coefficient was measured using “OX-TRAN-2 / 21” manufactured by MOCON under the conditions of 23 ° C., 60% RH and a cell area of 50 cm ² .

(Method for measuring terminal amino group concentration)
0.5 g of sample was dissolved in 30 mL of phenol / ethanol = 4/1 (volume ratio), 5 mL of methanol was added, and an automatic titrator with 0.01 N hydrochloric acid as a titrant (“COM-2000” manufactured by Hiranuma Seisakusho) Titration with The same operation titrated without adding a sample was used as a blank, and the terminal amino group concentration was calculated from the following formula.
Terminal amino group concentration (μeq / g) = (A−B) × f × 10 / C
(A: titer (mL), B: blank titer (mL), f: factor of normal solution, C: sample amount (g)).

(Measurement method of terminal carboxyl group concentration)
0.5 g of a sample was dissolved in 30 mL of benzyl alcohol, 10 mL of methanol was added, and titrated with an automatic titration apparatus (“COM-2000” manufactured by Hiranuma Seisakusho) with 0.01 N sodium hydroxide solution as a titrant. The same operation titrated without adding a sample was used as a blank, and the terminal carboxyl group concentration was calculated from the following formula.
Terminal carboxyl group concentration (μeq / g) = (A−B) × f × 10 / C
(A: titer (mL), B: blank titer (mL), f: factor of normal solution, C: sample amount (g)).

(Measurement method of semi-crystallization time)
When the pellet is melted at each temperature and the resin is crystallized at each temperature, the time for all to crystallize is called the crystallization time, and the time for reaching 50% crystallization is called the semi-crystallization time. The half crystallization time was measured by the depolarized intensity method. That is, when the sample pellets are irradiated with light and the sample pellets are crystallized, the amount of light transmission decreases and becomes stable when the amount of light transmission is stabilized. The time is defined as the crystallization time, and the amount of light transmission is 50%. The time to reach was defined as the half crystallization time. Although the crystallization time and the half crystallization time differ depending on the measurement temperature, in the following description, among the half crystallization times at each temperature, the one with the shortest half crystallization time is referred to as “half crystallization time”. Described. In addition, a “polymer crystallization rate measuring apparatus MK-701 type” manufactured by Kotaki was used to measure the crystallization time and the semi-crystallization time.

(Synthesis conditions by melt polymerization of polyamide resin)
After heating and melting the dicarboxylic acid in a reaction can at 170 ° C., the aromatic diamine is gradually and continuously added so that the molar ratio of the dicarboxylic acid to the dicarboxylic acid is about 1: 1 while stirring the contents. And the temperature was raised to 240 ° C. After completion of dropping, the temperature was raised to 260 ° C. and the reaction was continued. After completion of the reaction, the inside of the reaction can was slightly pressurized with nitrogen, the strand was extruded from a die head having holes, and pelletized with a pelletizer.

(Synthesis conditions by solid phase polymerization of polyamide resin)
The pellets obtained by melt polymerization by the above method were charged into a rotary tumbler equipped with a heating device, the pressure inside the tumbler was reduced to 1 torr or less while rotating, and the operation of bringing the pressure to normal pressure with nitrogen was performed three times. Thereafter, the inside of the apparatus was heated while rotating the tumbler to 30 torr or less, the inside of the apparatus was adjusted to 150 ° C. or more, and the reaction was performed at that temperature for a predetermined time. Then, it cooled to 60 degreeC and obtained the polyamide resin.

Example 1
Polyamide resin was synthesized by performing melt polymerization and solid phase polymerization under the above-mentioned synthesis conditions using metaxylylenediamine: sebacic acid: adipic acid in a molar ratio of 0.993: 0.4: 0.6. (Hereinafter, the polyamide resin is referred to as polyamide 1). The dropping time was 2 hours, the reaction time for melt polymerization was 1 hour, the pressure in the apparatus during solid phase polymerization was 1 torr or less, the polymerization temperature was 160 ° C., and the polymerization time was 4 hours. Polyamide 1 has a Tg of 73 ° C., a melting point of 184 ° C., a semi-crystallization time of 2000 seconds or more, a terminal amino group concentration of 18.8 μeq / g, a terminal carboxyl group concentration of 85.6 μeq / g, a number average molecular weight of 23,000, and an MFR of 240 ° C. Was 11.4 g / 10 min. Moreover, when the unstretched film was produced with the obtained polyamide 1 single-piece | unit and the oxygen permeability coefficient was calculated | required, it was 0.34cc * mm / (m < ² > * day * atm) (23 degreeC * 60% RH). . These results are shown in Table 1.

  Cobalt stearate was added to polyamide 1 as a transition metal catalyst by a side feed to molten polyamide 1 with a twin screw extruder so as to have a cobalt concentration of 400 ppm. Furthermore, a linear low density polyethylene (product name; manufactured by Nippon Polyethylene Co., Ltd.) “Harmolex” is used as a polyolefin resin in a mixture of the obtained polyamide and cobalt stearate (hereinafter referred to as cobalt stearate-containing polyamide 1). NC564A ”, MFR 3.5 g / 10 min (measured in accordance with JIS K7210), MFR 7.5 g / 10 min at 240 ° C., MFR 8.7 g / 10 min at 250 ° C., hereinafter referred to as LLDPE), and cobalt stearate Containing polyamide 1: LLDPE = 35: 65 In a weight ratio of 240 ° C., the mixture was melt-kneaded to obtain pellets made of an oxygen-absorbing resin composition.

  The obtained oxygen-absorbing resin composition was used as an oxygen-absorbing layer, and a two-layer / three-layer film 1 (thickness: 10 μm / 20 μm / 10 μm) having a sealant layer and an intermediate layer as LLDPE, with a width of 800 mm and 100 m / min. The intermediate layer surface was prepared by corona discharge treatment. The appearance of the obtained film was good, and HAZE was 20%. Alumina-deposited PET film (product name: manufactured by Toppan Printing Co., Ltd.) was used on the corona-treated surface side using an urethane dry laminate adhesive (product name: “AD817 / CAT-RT86L-60” manufactured by Toyo Morton Co., Ltd.). “GL-ARH-F”) / adhesive (3) / nylon (product name: “N1202”, 15) manufactured by Toyobo Co., Ltd./adhesive (3) / LLDPE (10) / oxygen-absorbing resin composition ( 20) An oxygen-absorbing multilayer film comprising an oxygen-absorbing multilayer body of LLDPE (10) was obtained. The numbers in parentheses mean the thickness of each layer (unit: μm). Using this oxygen-absorbing multilayer film, a 10 cm × 15 cm three-sided sealed bag was prepared, filled with 100 g of a powder seasoning “Ajinomoto” having a water activity of 0.35, and stored at 23 ° C. after sealing. The oxygen concentration and flavor in the bag after 7 days and 1 month storage were investigated. These results are shown in Table 2.

(Example 2)
An oxygen-absorbing multilayer film was obtained in the same manner as in Example 1 except that the weight ratio during melt-kneading was changed to cobalt stearate-containing polyamide 1: LLDPE = 55: 45. The same preservation test was conducted. These results are shown in Table 2.

(Example 3)
An oxygen-absorbing multilayer film was obtained in the same manner as in Example 1 except that the weight ratio at the time of melt kneading was changed to cobalt stearate-containing polyamide 1: LLDPE = 25: 75. The same preservation test was conducted. These results are shown in Table 2.

Example 4
An oxygen-absorbing multilayer film was obtained in the same manner as in Example 1 except that the weight ratio at the time of melt kneading was changed to cobalt stearate-containing polyamide 1: LLDPE = 17: 83. The same preservation test was conducted. These results are shown in Table 2.

(Example 5)
Polyamide resin was synthesized by performing melt polymerization and solid phase polymerization under the above-described synthesis conditions using metaxylylenediamine: sebacic acid: adipic acid in a molar ratio of 0.992: 0.3: 0.7. (Hereinafter, the polyamide resin is referred to as polyamide 2). The dropping time was 2 hours, the reaction time for melt polymerization was 1 hour, the pressure in the apparatus during solid phase polymerization was 1 torr or less, the polymerization temperature was 160 ° C., and the polymerization time was 4 hours. Polyamide 2 has a Tg of 78 ° C., a melting point of 194 ° C., a semi-crystallization time of 2000 seconds or more, a terminal amino group concentration of 19.5 μeq / g, a terminal carboxyl group concentration of 81.2 μeq / g, a number average molecular weight of 24500, MFR of 240 ° C. Was 10.5 g / 10 min. In addition, an unstretched film was prepared from the obtained polyamide 2 alone, and its oxygen permeability coefficient was determined to be 0.21 cc · mm / (m ² · day · atm) (23 ° C. · 60% RH). . These results are shown in Table 1.

  Thereafter, in the same manner as in Example 1, addition of cobalt stearate to polyamide 2, melt kneading with LLDPE, and the like were carried out to obtain oxygen-absorbing resin pellets. Furthermore, after obtaining an oxygen-absorbing multilayer film in the same manner as in Example 1, a three-side sealed bag was produced, and the same storage test as in Example 1 was performed. These results are shown in Table 2.

(Example 6)
Polyamide resin was synthesized by performing melt polymerization and solid phase polymerization under the above-mentioned synthesis conditions using metaxylylenediamine: sebacic acid: adipic acid in a molar ratio of 0.992: 0.7: 0.3. (Hereinafter, the polyamide resin is referred to as polyamide 3). The dropping time was 2 hours, the reaction time for melt polymerization was 1 hour, the pressure in the apparatus during solid phase polymerization was 1 torr or less, the polymerization temperature was 160 ° C., and the polymerization time was 4 hours. Polyamide 3 has a Tg of 65 ° C., a melting point of 170 ° C., a semicrystallization time of 2000 seconds or more, a terminal amino group concentration of 19.2 μeq / g, a terminal carboxyl group concentration of 80.0 μeq / g, a number average molecular weight of 25200, MFR with 240 ° C. Was 10.1 g / 10 min. In addition, an unstretched film was prepared from the obtained polyamide 3 alone, and its oxygen permeability coefficient was determined to be 0.84 cc · mm / (m ² · day · atm) (23 ° C. · 60% RH). . These results are shown in Table 1.

  Thereafter, in the same manner as in Example 1, addition of cobalt stearate to polyamide 3, melt kneading with LLDPE, and the like were carried out to obtain oxygen-absorbing resin pellets. Furthermore, after obtaining an oxygen-absorbing multilayer film in the same manner as in Example 1, a three-side sealed bag was produced, and the same storage test as in Example 1 was performed. These results are shown in Table 2.

(Example 7)
Using xylylenediamine: adipic acid: isophthalic acid in a molar ratio of 0.991: 0.9: 0.1, a polyamide resin is synthesized by melt polymerization and solid phase polymerization under the above synthesis conditions. (Hereinafter, the polyamide resin is referred to as polyamide 4). The dropping time was 2 hours, the reaction time for melt polymerization was 1 hour, the pressure in the apparatus during solid phase polymerization was 1 torr or less, the polymerization temperature was 205 ° C., and the polymerization time was 4 hours. This polyamide 4 had a Tg of 94 ° C., a melting point of 228 ° C., a half crystallization time of 300 seconds, a terminal amino group concentration of 14.8 μeq / g, a terminal carboxyl group concentration of 67.2 μeq / g, and a number average molecular weight of 23,000. Since it was near melting | fusing point at 240 degreeC, MFR was not able to be measured, MFR of 250 degreeC was measured, and MFR in 250 degreeC was 15.4 g / 10min. An unstretched film was prepared from the obtained polyamide 4 alone, and the oxygen permeability coefficient was determined. The oxygen permeability coefficient was 0.08 cc · mm / (m 2 · day · atm) (23 ° C. · 60% RH). It was. These results are shown in Table 1.

  Thereafter, except that the temperature at the time of melt kneading was changed to 250 ° C., addition of cobalt stearate to polyamide 4 and melt kneading with LLDPE were carried out in the same manner as in Example 1 to obtain oxygen-absorbing resin pellets. Furthermore, after obtaining an oxygen-absorbing multilayer film in the same manner as in Example 1, a three-side sealed bag was produced, and the same storage test as in Example 1 was performed. These results are shown in Table 2.

(Example 8)
Polyamide resin was synthesized by performing melt polymerization and solid phase polymerization under the above-mentioned synthesis conditions using metaxylylenediamine: sebacic acid: adipic acid in a molar ratio of 0.998: 0.4: 0.6. Thereafter, the terminal amino group concentration was measured (the terminal amino group concentration was 33.6 μeq / g). Next, after adding 1.5 equivalents of phthalic anhydride as a terminal blocking agent to the terminal amino group concentration, it is melt-kneaded at 200 ° C. with a twin screw extruder to seal the terminal amino group, Synthesized (hereinafter, the polyamide resin is referred to as polyamide 5). The dropping time was 2 hours, the reaction time for melt polymerization was 1 hour, the pressure in the apparatus during solid phase polymerization was 1 torr or less, the polymerization temperature was 160 ° C., and the polymerization time was 4 hours. Polyamide 5 has a Tg of 73 ° C., a melting point of 184 ° C., a semicrystallization time of 2000 seconds or more, a terminal amino group concentration of 15.8 μeq / g, a terminal carboxyl group concentration of 63.0 μeq / g, a number average molecular weight of 23200, MFR of 240 ° C. Was 13.0 g / 10 min. Moreover, when the unstretched film was produced with the obtained polyamide 5 single-piece | unit and the oxygen permeability coefficient was calculated | required, it was 0.74 cc * mm / (m <2> * day * atm) (23 degreeC * 60% RH). These results are shown in Table 1.

  Thereafter, in the same manner as in Example 1, addition of cobalt stearate to polyamide 5 and melt kneading with LLDPE were carried out to obtain oxygen-absorbing resin pellets. Furthermore, after obtaining an oxygen-absorbing multilayer film in the same manner as in Example 1, a three-side sealed bag was produced, and the same storage test as in Example 1 was performed. These results are shown in Table 2.

Example 9
Metaxylylenediamine and paraxylylenediamine are mixed at a ratio of 7: 3. These diamines and adipic acid are used in a molar ratio of 1: 1, and only a melt polymerization is performed under the above synthesis conditions to obtain a polyamide resin. After the synthesis, the terminal amino group concentration was measured (the terminal amino group concentration was 35.7 μeq / g). Next, after adding 1.5 equivalents of phthalic anhydride as a terminal blocking agent to the terminal amino group concentration, it is melt-kneaded at 200 ° C. with a twin screw extruder to seal the terminal amino group, Synthesized (hereinafter, the polyamide resin is referred to as polyamide 6). However, the dropping time was 2 hours, the polymerization temperature after completion of dropping of metaxylylenediamine in melt polymerization was 277 ° C., and the reaction time was 30 minutes. This polyamide 6 had a Tg of 87 ° C., a melting point of 259 ° C., a half crystallization time of 18 seconds, a terminal amino group concentration of 25.8 μeq / g, a terminal carboxyl group concentration of 75.6 μeq / g, and a number average molecular weight of 18,500. Moreover, since it was near melting | fusing point at 250 degreeC, MFR was not able to be measured, MFR of 270 degreeC was measured, and MFR in 270 degreeC was 29.8 g / 10min. An unstretched film was prepared from the obtained polyamide 6 alone, and the oxygen permeability coefficient was determined. The oxygen permeability coefficient was 0.13 cc · mm / (m ² · day · atm) (23 ° C. · 60% RH). there were. These results are shown in Table 1.

  Thereafter, except that the temperature at the time of melt kneading was set to 270 ° C., addition of cobalt stearate to polyamide 6 and melt kneading with LLDPE were performed in the same manner as in Example 1 to obtain oxygen-absorbing resin pellets. Furthermore, after obtaining an oxygen-absorbing multilayer film in the same manner as in Example 1, a three-side sealed bag was produced, and the same storage test as in Example 1 was performed. These results are shown in Table 2.

(Example 10)
Cobalt stearate was added to LLDPE by side feed to the melted LLDPE with a twin screw extruder so that the cobalt concentration was 600 ppm. Furthermore, polyamide 1 was melt-kneaded at 240 ° C. in a weight ratio of polyamide 1: cobalt stearate-containing LLDPE1 = 35: 65 to the obtained mixture of LLDPE and cobalt stearate to obtain oxygen-absorbing resin pellets.

Thereafter, after obtaining an oxygen-absorbing multilayer film in the same manner as in Example 1, a three-sided sealed bag was prepared, and the same storage test as in Example 1 was performed. These results are shown in Table 2.

(Comparative Example 1)
After producing an oxygen-absorbing multilayer film in the same manner as in Example 1 except that the weight ratio during melt-kneading was changed to cobalt stearate-containing polyamide 1: LLDPE = 80: 20, a three-side sealed bag was produced. The same preservation test was conducted. These results are shown in Table 2.

(Comparative Example 2)
After producing an oxygen-absorbing multilayer film in the same manner as in Example 1 except that it was not melt-kneaded with LLDPE and made of only cobalt stearate-containing polyamide 1, a three-side sealed bag was produced and the same as in Example 1. A storage test was performed. These results are shown in Table 2.

(Comparative Example 3)
After producing an oxygen-absorbing multilayer film in the same manner as in Example 1 except that the weight ratio during melt-kneading was changed to cobalt stearate-containing polyamide 1: LLDPE = 10: 90, a three-side sealed bag was produced. The same preservation test was conducted. These results are shown in Table 2.

(Comparative Example 4)
Polyamide was used in the same manner as in Example 5 except that metaxylylenediamine: sebacic acid: adipic acid was used in a molar ratio of 0.998: 0.4: 0.6 and solid phase polymerization was not performed. A resin was synthesized (hereinafter, the polyamide resin is referred to as polyamide 7). Polyamide 7 had a Tg of 73 ° C., a melting point of 184 ° C., a semicrystallization time of 2000 seconds or more, a terminal amino group concentration of 39.1 μeq / g, a terminal carboxyl group concentration of 70.2 μeq / g, and a number average molecular weight of 17,800. Moreover, MFR in 240 degreeC was 51.0 g / 10min. Moreover, when an unstretched film was prepared from the obtained polyamide 7 alone and its oxygen permeability coefficient was determined, it was 0.34 cc · mm / (m ² · day · atm) (23 ° C. · 60% RH). . These results are shown in Table 1.

  Thereafter, in the same manner as in Example 1, addition of cobalt stearate to polyamide 7, melt kneading with LLDPE, and the like were performed to obtain oxygen-absorbing resin pellets. Furthermore, after obtaining an oxygen-absorbing multilayer film in the same manner as in Example 1, a three-side sealed bag was produced, and the same storage test as in Example 1 was performed. These results are shown in Table 2.

(Comparative Example 5)
A polyamide resin was synthesized in the same manner as in Example 5 except that metaxylylenediamine and adipic acid were used in a molar ratio of 0.999: 1 and the polymerization time for solid phase polymerization was 2 hours (hereinafter referred to as “polyamide resin”). The polyamide resin is expressed as polyamide 8). This polyamide 8 had a Tg of 78 ° C., a melting point of 237 ° C., a half crystallization time of 25 seconds, a terminal amino group concentration of 34.8 μeq / g, a terminal carboxyl group concentration of 58.6 μeq / g, and a number average molecular weight of 21,800. Moreover, since it was near melting | fusing point at 240 degreeC, MFR was not measurable, MFR of 260 degreeC was measured, and MFR in 260 degreeC was 18.9 g / 10min. An unstretched film was prepared from the obtained polyamide 8 alone, and the oxygen permeability coefficient was determined. The oxygen permeability coefficient was 0.09 cc · mm / (m ² · day · atm) (23 ° C. · 60% RH). there were. These results are shown in Table 1.

  Thereafter, except that the temperature at the time of melt kneading was changed to 260 ° C., addition of cobalt stearate to polyamide 8 and melt kneading with LLDPE were carried out in the same manner as in Example 1 to obtain oxygen-absorbing resin pellets. Furthermore, after obtaining an oxygen-absorbing multilayer film in the same manner as in Example 1, a three-side sealed bag was produced, and the same storage test as in Example 1 was performed. These results are shown in Table 2.

(Example 11)
Using the oxygen-absorbing multilayer film obtained in Example 1, this film was processed into a self-supporting bag (130 × 175 × 35 mm) having two side films and one bottom film with the intermediate layer side as the inner surface. Workability was good. The bag was filled with a total of 200 g together with a solution containing radish and acetic acid at a speed of 40 bags / minute by high-speed automatic filling. As a result, the bag opening was good and heat sealing could be performed without any problem. 100 filled and sealed bags were boiled at 90 ° C. for 30 minutes, stored at 23 ° C., and the flavor of the radish, oxygen concentration in the bag and the appearance of the self-supporting bag after one month were investigated. The radish was visible from the outside of the bag, the flavor and color tone of the radish were well maintained, the bag appearance was not abnormal, and the oxygen concentration in the bag was 0.1% or less.

(Example 12)
A two-type three-layer film 2 (thickness: 10 μm / 20 μm / 40 μm) in which the oxygen-absorbing resin composition obtained in Example 1 is an oxygen-absorbing layer and the sealant layer and the intermediate layer are LLDPE is 80 m in width and 800 m in width. The intermediate layer surface was prepared by corona discharge treatment at / min. The appearance of the obtained film was slightly lower than that of the two-kind three-layer film 1, and the HAZE was 30%. Alumina-deposited PET film (product name; manufactured by Toppan Printing Co., Ltd.) was used on the corona-treated surface side using an urethane dry laminate adhesive (product name: “AD817 / CAT-RT86L-60” manufactured by Toyo Morton Co., Ltd.). “GL-ARH-F”) / adhesive (3) / nylon (product name: “N1202”, 15) manufactured by Toyobo Co., Ltd./adhesive (3) / LLDPE (40) / oxygen-absorbing resin composition ( 20) An oxygen-absorbing multilayer film comprising an oxygen-absorbing multilayer body of LLDPE (10) was obtained. The numbers in parentheses mean the thickness of each layer (unit: μm). Next, in the same manner as in Example 11, when a total of 200 g was filled together with a solution containing radish and acetic acid, heat sealing could be performed without any problem. The filled bag was boiled at 90 ° C. for 30 minutes and stored at 23 ° C., and the flavor of the radish, oxygen concentration in the bag, and the appearance of the self-supporting bag after one month were investigated. The flavor and color tone of the radish were well maintained, and the oxygen concentration in the bag was 0.1% or less, but the appearance of the bag was slightly deteriorated.

(Example 13)
In the same manner as in Example 1, a two-kind three-layer film 1 was produced, and this was used for extrusion laminating with low-density polyethylene (product name: “Mirason 18SP” manufactured by Mitsui Chemicals, Inc.), and bleached kraft paper (tsubo 340 g / m ² ) / urethane-based dry laminating adhesive (product name: “AD817 / CAT-RT86L-60”, 3) manufactured by Toyo Morton Co., Ltd./alumina-deposited PET film (product name: Toppan Printing Co., Ltd.) “GL-ARH-F”, 12) / urethane anchor coating agent (“EL-557A / B”, 0.5) manufactured by Toyo Morton Co., Ltd./low density polyethylene (20) / LLDPE (10) / oxygen An oxygen-absorbing multilayer paper base material of the absorbent resin composition (20) / LLDPE (10) was obtained. This base material was formed into a 1-liter paperbell-top type paper container. The moldability of the container was good. This paper container was filled with barley shochu, sealed, and stored at 23 ° C. The flavor after 1 month and the oxygen concentration in the paper container were 0.1% or less, and the flavor of the barley shochu was well maintained.

(Example 14)
Instead of LLDPE, ethylene-propylene block copolymer (product name: “NOVATEC FG3DC” manufactured by Nippon Polypro Co., Ltd., MFR 9.5 g / 10 min at 230 ° C., MFR 10.6 g / 10 min at 240 ° C., hereinafter referred to as PP Oxygen-absorbing resin pellets were obtained in the same manner as in Example 1 except that Next, a two-kind three-layer film 3 (thickness: 15 μm / 30 μm / 15 μm) in the same manner as in Example 1 except that the oxygen-absorbing resin pellet was used as a core layer, and the sealant layer and intermediate layer were replaced with PP instead of LLDPE. Was made. The obtained film had a HAZE of 66%. Urethane vapor-deposited PET (product name: manufactured by Toppan Printing Co., Ltd.) was used on the corona-treated surface side using an urethane dry laminate adhesive (product name: “AD817 / CAT-RT86L-60” manufactured by Toyo Morton Co., Ltd.). GL-ARH-F ", 12) / adhesive (3) / nylon (product name:" N1202 ", 15) manufactured by Toyobo Co., Ltd./adhesive (3) / PP (15) / oxygen-absorbing resin composition An oxygen absorbing multilayer film of (30) / PP (15) was obtained. Using this oxygen-absorbing multilayer film, a 10 × 20 cm three-side sealed bag was prepared, a circular steaming port having a diameter of 2 mm was provided in a part thereof, and the periphery of the steaming port was temporarily attached with a label seal. . The bag was filled with beef stew containing carrot and meat, sealed, retort cooked at 124 ° C. for 30 minutes, heat sterilized, and stored at 23 ° C. The beef stew inside the bag was visible. One month later, the bag was heated as it was for about 4 minutes in a microwave oven, and after about 3 minutes, the bag was inflated, the temporarily attached label seal part was peeled off, and it was confirmed that steam was emitted from the steaming port. After cooking, the flavor of the beef stew and the color tone of the carrot were examined. The appearance of the carrot was kept well, and the flavor of the beef stew was good.

(Comparative Example 6)
Iron powder having an average particle diameter of 20 μm and calcium chloride were mixed at a ratio of 100: 1 and kneaded at a weight ratio of LLDPE of 30:70 to obtain an iron powder-based oxygen-absorbing resin composition A. The iron powder-based oxygen-absorbing resin composition A was used as a core layer, and an attempt was made to produce a two-layer / three-layer film in the same manner as in Example 1. However, irregularities of the iron powder occurred on the film surface, and no film was obtained. Therefore, an iron powder-based oxygen-absorbing resin composition A was extruded and laminated at a thickness of 20 μm as an oxygen-absorbing layer on LLDPE having a thickness of 40 μm, and a laminate film was obtained in which the oxygen-absorbing layer surface was subjected to corona discharge treatment. This laminated film was laminated with bleached kraft paper in the same manner as in Example 13, and bleached kraft paper (basis weight 340 g / m ² ) / urethane-based dry laminating adhesive (product name: “AD817 / CAT-” manufactured by Toyo Morton Co., Ltd.). RT86L-60 ”, 3) / alumina-deposited PET film (product name:“ GL-ARH-F ”, manufactured by Toppan Printing Co., Ltd., 12) / urethane anchor coating agent (“ EL-557A / manufactured by Toyo Morton Co., Ltd.) B ”, 0.5) / low density polyethylene (product name;“ Mirason 18SP ”manufactured by Mitsui Chemicals, Inc., 20) / oxygen absorbing multilayer of iron powder-based oxygen absorbing resin composition A (20) / LLDPE (40) An attempt was made to produce a gobeltop paper container made of a paper base material, but it was thick and it was difficult to produce the corners of the paper container. The container production speed was reduced and defective products were finally removed to obtain a container. Thereafter, a storage test of barley shochu was conducted in the same manner as in Example 13, but an aldehyde odor was generated at the time of opening, and the flavor was significantly reduced.

(Comparative Example 7)
An iron powder-based oxygen-absorbing resin composition B was obtained in the same manner as in Comparative Example 6 except that PP was used instead of LLDPE. Similarly, a laminated film of iron powder-based oxygen-absorbing resin composition B (20) / PP (40) was prepared in the same manner as in Comparative Example 6 except that PP was used instead of LLDPE, and then the oxygen-absorbing layer surface was corona. Discharge treatment was performed. Thereafter, in the same manner as in Example 14, alumina-deposited PET (product name: “GL-ARH-F”, 12 manufactured by Toppan Printing Co., Ltd.) / Adhesive (3) / nylon (product name: manufactured by Toyobo Co., Ltd.) An oxygen-absorbing multilayer film of “N1202”, 15) / adhesive (3) / iron powder-based oxygen-absorbing resin composition B (20) / PP (40) was obtained. As a result of performing the same test as in Example 14 using the obtained oxygen-absorbing multilayer film, the flavor of the beef stew was well maintained, but the contents were not visible, and the surface was bubbled when heated in the microwave. Unevenness occurred.

  As is clear from Examples 1 to 12, the oxygen-absorbing multilayer body of the present invention is excellent in oxygen absorption performance, workability and strength, and has content visibility.

  In contrast, Comparative Examples 1 and 2 in which the content of the polyamide resin A in the oxygen absorption layer exceeded 60% by weight and Comparative Example 3 in which the content was less than 15% by weight had insufficient oxygen absorption performance. Met. In particular, as is clear from the comparison between Comparative Examples 1 and 2 and Examples 1 to 3, if the content of the polyamide resin A in the oxygen absorption phase is large, good oxygen absorption performance is not necessarily obtained. It was.

  On the other hand, compared with Example 1, in Comparative Example 4 in which solid phase polymerization was not performed and in Comparative Example 5 in which the solid phase polymerization time was shortened, the terminal amino group concentration of the obtained polyamide resin was 30 μeq / g. The oxygen absorption performance was not satisfactory. Also, the appearance of the film roll deteriorated.

  As is clear from Examples 13 to 14, the oxygen-absorbing multilayer body of the present invention is excellent in processability into a paper container, and it is good even if a steam inlet is attached during storage of alcoholic beverages or microwave cooking. It became a safe storage container. Moreover, it also has internal visibility, and the color tone of the contents could be confirmed.

  The present invention provides resin strength by providing an intermediate layer composed of a polyolefin resin between both layers of a multilayer body having an oxygen-absorbing resin layer and a gas barrier layer obtained by blending a specific polyamide resin and a transition metal catalyst with a polyolefin resin in a specific ratio. Is provided, and an oxygen-absorbing multilayer body having excellent interlayer strength is provided.

Claims (6)

  Oxygen absorption in which at least four layers of a sealant layer made of polyolefin resin, an oxygen absorption layer containing polyolefin resin, a transition metal catalyst and a polyamide resin, an intermediate layer made of polyolefin resin, and a gas barrier layer made of a gas barrier material are laminated in this order. A multilayer body, wherein the polyamide resin is a polyamide resin having a terminal amino group concentration of 30 μeq / g or less obtained by polycondensation of an aromatic diamine and a dicarboxylic acid, and the transition metal catalyst in the oxygen absorbing layer And the total content of the polyamide resin is 15 to 60% by weight based on the total amount of the oxygen-absorbing resin layer.   The oxygen-absorbing multilayer body according to claim 1, wherein adipic acid, sebacic acid, isophthalic acid or a mixture thereof is used as the dicarboxylic acid.   3. The oxygen-absorbing multilayer body according to claim 1, wherein paraxylylenediamine, metaxylylenediamine, or a mixture thereof is used as the aromatic diamine.   The oxygen-absorbing multilayer body according to any one of claims 1 to 3, wherein the transition metal catalyst is cobalt stearate.   5. The molar ratio of the dicarboxylic acid in obtaining the polyamide resin is sebacic acid: adipic acid = 0.3 to 0.7: 0.7 to 0.3. 5. 2. The oxygen-absorbing multilayer body according to 1.   The molar ratio of the dicarboxylic acid when obtaining the polyamide resin is set to adipic acid: isophthalic acid = 0.7 to 0.97: 0.3 to 0.03. 2. The oxygen-absorbing multilayer body according to 1.