JP2010013638A - Oxygen-absorbing resin composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an oxygen-absorbing resin excellent in oxygen-absorbing performance, which is excellent in resin processability and has no limit in applications. <P>SOLUTION: The oxygen-absorbing resin composition at least includes a polyolefin resin, a transition metal catalyst, and a polyamide resin. The polyamide resin has a melting point of 200°C or lower and a glass transition temperature of 80°C or lower. The total content of the transition metal catalyst and the polyamide resin is 20 to 60% by weight. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an oxygen-absorbing resin composition that exhibits excellent oxygen-absorbing performance and is free from strength reduction and odor generation due to oxidative degradation of the resin. The present invention also relates to an oxygen-absorbing multilayer body excellent in resin processability using the oxygen-absorbing resin composition, and an oxygen-absorbing multilayer container formed by thermoforming the multilayer body.

  Conventionally, containers such as metal cans, glass bottles, and various plastic packages are known as packaging containers, but quality deterioration due to oxygen in the packaging containers is a problem. Therefore, in recent years, as one of deoxygenation packaging technologies, a container is constituted by a multilayer material in which an oxygen absorption layer composed of an oxygen-absorbing resin composition in which an iron-based oxygen absorber is blended with a thermoplastic resin, 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 carried out. For example, in an oxygen-absorbing multilayer sheet, an oxygen-absorbing layer made of an oxygen-absorbing resin composition is added to a conventional gas-barrier multilayer sheet formed by laminating an oxygen-permeable layer and a gas barrier layer to allow oxygen permeation from the outside. It is used as a function of preventing oxygen in the container from being added to the function of preventing, and is manufactured using a conventionally known manufacturing method such as a co-extrusion method or various laminating methods (see Patent Document 1).

  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 absorbers obtained by molding the resin composition, packaging materials, and multilayer laminated films for packaging (see Patent Documents 2 to 6).

  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.

  Furthermore, when forming an oxygen-absorbing multilayer body using iron powder, the use of iron powder results in high weight, and defective molding occurs when molding films, sheets, hollow molded bodies, and other molded bodies. Have a problem. Examples thereof include neck-in at the time of film and sheet molding, uneven thickness, and drawdown at the time of molding a hollow molded body. Moreover, when it shape | molds, it also has the problem that an unevenness | corrugation arises on the surface.

  On the other hand, a resin composition that contains a transition metal catalyst and oxidizes a polyamide resin or the like to develop an oxygen absorbing function causes the polyamide resin to oxidize, resulting in a decrease in strength due to oxidative degradation of the resin, and the strength of the packaging container itself. It has the problem of being lowered.

  Furthermore, MXD6, which is a polyamide obtained by polycondensation of metaxylylenediamine and adipic acid, is used as an indicator of an oxidation reaction with a polyamide resin and a transition metal catalyst. A transition metal was mixed with MXD6. In the system, there is a problem that the oxygen absorption ability is low in order to use it as an oxygen-absorbing resin composition and to preserve an object to be stored satisfactorily. In addition, when polyolefin resin used for sealing layer materials such as packaging films is blended into a system in which transition metal is mixed with MXD6, the melting point of the resins is greatly different, and the molding processability when used as packaging containers for films and the like is inferior. Usually, a blend with a polyester resin such as polyethylene terephthalate (hereinafter referred to as PET) or a relatively high melting point resin such as nylon 6 has been used.

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

  The objective of this invention is providing the resin composition excellent in oxygen absorption performance, resin strength, and resin processability which solved the said problem. Another object of the present invention is to provide an oxygen-absorbing multilayer body excellent in appearance using the composition, and an oxygen-absorbing multilayer container which is formed by thermoforming the multilayer body and whose contents are visible.

  The inventors of the present invention blended a specific polyamide resin and a transition metal with a polyolefin resin at a specific ratio, thereby improving oxygen absorption performance, maintaining the resin strength after storage, and excellent oxygen molding processability. It has been found that an absorbent resin composition can be obtained. Moreover, it discovered that the oxygen absorption multilayer body excellent in the external appearance which used this composition was obtained, and also discovered the oxygen absorption multilayer container which can visually recognize the contents formed by thermoforming this multilayer sheet.

  That is, the present invention is an oxygen-absorbing resin composition containing at least a polyolefin resin, a transition metal catalyst, and a polyamide resin, wherein the polyamide resin has a melting point of 200 ° C. or less and a glass transition temperature (hereinafter referred to as Tg). Is an oxygen-absorbing resin composition, wherein the total content of the transition metal catalyst and the polyamide resin is 20 to 60% by weight.

  In addition, the present invention provides an oxygen-absorbing multilayer in which at least three layers of an oxygen-permeable layer made of a thermoplastic resin, an oxygen-absorbing resin layer made of the oxygen-absorbing resin composition, and a gas barrier layer made of a gas-barrier substance are laminated in this order. And an oxygen-absorbing multilayer container formed by thermoforming the body and the oxygen-permeable layer of the oxygen-absorbing multilayer body inside.

  According to the present invention, an oxygen-absorbing resin composition, an oxygen-absorbing multilayer body, and a multilayer body that have high oxygen-absorbing performance, high moldability, and transparency, and that hardly deteriorate in strength due to oxidation of polyamide resin are thermoformed. An oxygen-absorbing multilayer container can be provided.

  The oxygen-absorbing resin composition of the present invention comprises at least a polyamide resin having a melting point of 200 ° C. or lower and a Tg of 80 ° C. or lower (hereinafter, the polyamide resin is particularly referred to as “polyamide resin A”), a transition metal catalyst, and a polyolefin resin. And the total content of the transition metal catalyst and the polyamide resin is 20 to 60% by weight. Hereinafter, details of each component constituting the composition will be described.

  The oxygen absorption performance of the oxygen-absorbing resin composition is considered to be better when there are more polyamide resins to which a transition metal having oxygen-absorbing ability is added. Surprisingly, the polyamide resin A is mixed with a polyolefin resin and is fixed. It was found that a high oxygen absorption ability was exhibited when blended at a ratio of.

  In the present invention, as the polyamide resin A, those having a low melting point and Tg are preferably used in consideration of the workability with the polyolefin resin and the oxygen absorption performance.

The polyamide resin A in the present invention is obtained by a polycondensation reaction between a diamine and a dicarboxylic acid. As the diamine for producing the polyamide resin A, metaxylylenediamine is preferably used from the viewpoint of oxygen absorption performance, and 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 include C8 to C12 aliphatic dicarboxylic acids, specifically, suberic acid, azelaic acid, sebacic acid, and dodecanedioic acid. Of these, sebacic acid is particularly preferable because it provides a melting point and Tg that are easy to process. Various dicarboxylic acids and aromatic dicarboxylic acids may be incorporated as copolymerization components in various dicarboxylic acids as long as the performance is not affected. The obtained polyamide resin A has a melting point of preferably 200 ° C. or lower, more preferably 190 ° C. or lower. Tg is preferably 80 ° C. or lower, and particularly preferably 75 ° C. or lower. The obtained polyamide resin A preferably has a low oxygen barrier property, and preferably has an oxygen permeability coefficient of 0.3 cc · mm / (m ² · day · atm) (23 ° C. · 60% RH) or more. It is more preferably 5 cc · mm / (m ² · day · atm) (23 ° C. · 60% RH) or more.

  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 8 g / 10 minutes, 240 ° C., 4 Those of ˜12 g / 10 min are preferably used. In this case, when the resin is processed at a temperature at which the difference between the MFR of the polyolefin resin and the MFR of the polyamide resin A is about ± 3 g / 10 minutes, the kneaded state becomes good and a processed product having no problem in the appearance of the multilayer body is obtained. be able to. The MFR of the polyamide resin A can be adjusted by adjusting the molecular weight by solid phase polymerization. The polyamide resin A obtained by the polycondensation reaction of diamine and dicarboxylic acid is preferably a method of undergoing two steps of solid phase polymerization after melt polymerization. The number average molecular weight of the polyamide resin A obtained by solid phase polymerization is preferably 20000 to 25000, particularly preferably 21000 to 24000. In addition, unless otherwise indicated, MFR as used in this application is MFR of the said resin measured on the conditions of load 2160g in the specific temperature using the apparatus based on JISK7210, and is "g / 10min." It is expressed with the measured temperature in units of.

  When incorporating diamines such as metaxylylenediamine, C8-C12 aliphatic dicarboxylic acids such as suberic acid, azelaic acid, sebacic acid, dodecanedioic acid and other dicarboxylic acids as copolymerization components, Copolymerization is carried out so that the molar ratio of diamine such as amine: C8-C12 aliphatic dicarboxylic acid such as sebacic acid: other dicarboxylic acid such as adipic acid and isophthalic acid is 100: 50 or more and 50 or less. May be.

  Polyolefin resins used in the oxygen-absorbing resin composition of the present invention include high-density polyethylene, medium-density polyethylene, low-density polyethylene, linear low-density polyethylene, ultra-low-density polyethylene, various polyethylenes such as polyethylene by metallocene catalyst, polystyrene Polypropylenes such as polymethylpentene, propylene homopolymer, propylene-ethylene block copolymer, propylene-ethylene random copolymer can be used alone or in combination. 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 to the oxygen-absorbing resin composition. The addition amount of the maleic anhydride-modified product is preferably about 1 to 30%, particularly preferably 3 to 15% with respect to the polyolefin resin. The MFR of polyolefin resin is preferably 3 to 8 g / 10 minutes at 200 ° C. and 4 to 12 g / 10 minutes at 240 ° C. in consideration of film processability.

  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 oxygen-absorbing resin composition of the present invention include compounds of first transition elements 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 a butanetetracarboxylic acid, benzoic acid, toluic acid, o-phthalic acid, isophthalic acid, terephthalic acid, trimesic acid, or the like, or a mixture of aromatic carboxylates 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. If the addition amount is small, the oxygen absorption performance is lowered, and if it is too much, the resin processability is adversely affected.

  It is preferable to mix the polyamide resin A to which the transition metal catalyst is added and the polyolefin resin to obtain an oxygen-absorbing resin composition. The content of the polyamide resin A containing the transition metal catalyst in the oxygen-absorbing resin composition is preferably 20 to 60% by weight, particularly preferably 30 to 50% by weight. When the content of the polyamide resin A containing the transition metal catalyst in the oxygen-absorbing resin composition is less than 20% 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.

  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.

  The terminal amino group concentration of the polyamide resin A in the present invention is preferably 1 to 30 μeq / g, and more preferably 1 to 25 μeq / g. When the terminal amino group concentration is in the range of 1 to 30 μeq / g, the oxygen-absorbing resin composition can obtain higher oxygen absorption performance.

  The oxygen-absorbing resin composition of the present invention can be used as an oxygen absorbent material. That is, an oxygen-absorbing resin composition in the form of a pellet or sheet may be filled into a breathable packaging material and used as a sachet-shaped oxygen absorber. When making into pellet form, in order to keep contact with oxygen, it is preferable to grind | pulverize and make into powder form. Moreover, when setting it as a sheet form, it is preferable to extend | stretch and to provide a space | gap between the sea-island-like layers of the polyamide resin A and the polyolefin resin. As the polyolefin resin for stretching, high-density polyethylene is preferably used.

Further, by using the oxygen-absorbing resin composition of the present invention, at least 3 of an oxygen-permeable layer made of a thermoplastic resin, an oxygen-absorbing resin layer containing the oxygen-absorbing resin composition of the present invention, and a gas barrier layer made of a gas barrier material. It can be set as the oxygen absorption multilayer body by which a layer is laminated | stacked in this order, For example, it can be used for the use which comprises all or one part of the main body and lid | cover of a container, and a packaging material. Hereinafter, the details of each layer and each composition of the oxygen-absorbing multilayer body will be described.

The thermoplastic resin used for the oxygen permeable layer includes high-density polyethylene, medium-density polyethylene, low-density polyethylene, linear low-density polyethylene, ultra-low-density polyethylene, various polyethylenes such as polyethylene using a metallocene catalyst, polystyrene, and polymethylpentene. , Polypropylenes such as a propylene homopolymer, a propylene-ethylene block copolymer, and a propylene-ethylene random copolymer can be used alone or in combination. 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. The MFR of the thermoplastic resin is preferably 3 to 8 g / 10 minutes at 200 ° C. and 4 to 12 g / 10 minutes at 240 ° C. in consideration of film processability. The oxygen permeability of the oxygen permeable layer is preferably 10 cc / (m ² · day · atm) (23 ° C. · 60% RH) or more. The thermoplastic resin used for the oxygen-permeable layer is preferably the same type as the polyolefin resin used for the oxygen-absorbing resin layer, considering the processability and adhesion of the resin.

  The thermoplastic resin used for the oxygen permeable layer includes coloring pigments such as titanium oxide, antioxidants, slip agents, antistatic agents, stabilizers, lubricants and other additives, calcium carbonate, clay, mica, silica, etc. You may add a filler, a deodorizing agent, etc. In particular, it is preferable to add an antioxidant in order to recycle and reprocess offcuts generated during production.

  The oxygen-absorbing resin composition used for the oxygen-absorbing resin layer contains at least a polyamide resin A, a transition metal catalyst, and a polyolefin resin, and the total content of the transition metal catalyst and the polyamide resin A is 20 to 60% by weight. The details of the resin composition are as described above.

As the gas barrier material used for the gas barrier layer, a gas barrier thermoplastic resin, a gas barrier thermosetting resin, various deposited films such as silica, alumina, and aluminum, and a metal foil such as an aluminum foil can be used. Examples of the gas barrier thermoplastic resin include ethylene-vinyl alcohol copolymer, MXD6, and polyvinylidene chloride. Examples of the gas barrier thermosetting resin include amine-epoxy curing agents. The oxygen permeability of the gas barrier layer is preferably less than 10 cc / (m ² · day · atm) (23 ° C. · 60% RH).

  Although there is no restriction | limiting in particular in the thickness of the oxygen absorption resin layer in the oxygen absorption multilayer body of this invention, 5-200 micrometers is preferable and 10-100 micrometers is especially preferable. If the thickness is too small, problems occur in workability and oxygen absorption performance, and if it is too large, problems such as processability and cost occur. Further, the thickness of the oxygen permeable layer is preferably less because the oxygen permeable layer becomes an isolation layer from the oxygen absorbing resin layer, but is preferably 5 to 200 μm, particularly preferably 10 to 80 μm. If it is too large, the oxygen absorption performance will be reduced, and if it is too small, there will be a problem in workability.

  The thickness when the gas barrier thermoplastic resin is used for the gas barrier layer is preferably 5 to 200 μm, particularly preferably 10 to 100 μm. If the thickness is too small, there will be problems in workability and gas barrier properties, and if it is too large, problems such as processability and cost will occur. When using a gas barrier thermosetting resin such as an amine-epoxy curing agent for the gas barrier adhesive layer, the thickness is preferably from 0.1 to 100 μm, particularly preferably from 0.5 to 20 μm. If the thickness is too small, there will be a problem in gas barrier properties, and if it is too large, problems such as processability and cost will occur.

  Considering the processability of the deoxidizing multilayer, the thickness ratio of the oxygen permeable layer and the oxygen absorbing resin layer is preferably 1: 1 to 1: 3, and 1: 1.5 to 1: 2.5 Particularly preferred. Furthermore, in consideration of processability, it is preferable to interpose an intermediate layer made of polyolefin resin between the gas barrier layer and the oxygen-absorbing resin layer. The thickness of the intermediate layer is preferably substantially the same as the thickness of the oxygen permeable layer in view of workability. In this case, considering variations due to processing, the thickness is the same if the thickness ratio is within ± 10%.

  The oxygen-absorbing multilayer body of the present invention comprises at least three layers of an oxygen-permeable layer made of a thermoplastic resin, an oxygen-absorbing resin layer containing at least a polyolefin resin, a transition metal catalyst and a polyamide resin, and a gas barrier layer made of a gas barrier material. Although they are laminated in order, other layers may be added.

  For example, in order to prevent damage to the gas barrier layer and pinholes, it is preferable to provide a protective layer made of a thermoplastic resin inside and outside the gas barrier layer. Examples of the resin used for the protective layer include polyethylenes such as high density polyethylene, polypropylenes such as propylene homopolymer, propylene-ethylene random copolymer, propylene-ethylene block copolymer, nylon 6, nylon 6,6 and the like. Polyamides, polyesters such as PET, and combinations thereof.

  About the manufacturing method of an oxygen absorption multilayer body, well-known methods, such as a co-extrusion method, various lamination methods, and various coating methods, can be utilized according to the property of various materials, the process objective, a process process, etc. For example, for film and sheet molding, a method of manufacturing by extruding from an extruder attached to a resin composition melted through a T die, a circular die or the like, or applying an adhesive to an oxygen absorbing film or sheet, and other films There is a method of manufacturing by bonding to a sheet. In addition, by using an injection machine, molten resin can be molded into a multilayer container having a predetermined shape by co-injection or sequential injection into an injection mold through a multilayer multiple die.

  The oxygen-absorbing multilayer body of the present invention can be prepared as a film, processed into a bag shape and a lid material, and used. In addition, a paper base material can be laminated on the outer layer of the gas barrier layer to be used as an oxygen-absorbing paper container. Considering processability when laminated with a paper base material to form a paper container, the inner portion of the gas barrier layer is preferably 50 μm or less, and particularly preferably 40 μm or less. 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.

  Further, the oxygen-absorbing multilayer body of the present invention is produced as a sheet, and a predetermined method such as tray, cup, bottle, tube, PTP (press-through pack) or the like is formed by a molding method such as vacuum forming, pressure forming, or plug assist molding. It can be thermoformed into a shaped oxygen absorbing multilayer container. The obtained oxygen-absorbing multilayer container can be subjected to a boil treatment at 80 to 100 ° C., a semi-retort, a retort, and a high retort treatment at 100 to 135 ° C. 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.

  By using the oxygen-absorbing multilayer body and the oxygen-absorbing multilayer container of the present invention as a part or all of the sealing packaging container with the oxygen-permeable layer inside, in addition to oxygen that slightly enters from the outside of the container, oxygen in the container It is possible to prevent deterioration of the contents stored in the container due to oxygen.

  Since the oxygen-absorbing multilayer body and oxygen-absorbing multilayer container of the present invention can absorb oxygen regardless of the presence or absence of moisture in the object to be preserved, powder seasonings, powdered coffee, coffee beans, rice, tea, beans, rice cakes It can be suitably used for dried foods such as rice crackers and health foods such as pharmaceuticals and vitamins. In addition, the oxygen-absorbing resin composition obtained in the present invention is different from the conventional oxygen-absorbing resin composition using iron powder, such as alcohol drinks and carbonated drinks that cannot be stored in the presence of iron, acetic acid-containing food applications, Since the container is sterilized, the container can be suitably used for sterilization with hydrogen peroxide.

  Other items to be preserved include processed rice such as polished rice, cooked rice, red rice, and glutinous rice, cooked foods such as soup, stew, and curry, fruits, mutton, pudding, cakes, buns, jams, and other sweets, tuna, and fish Seafood products such as shellfish, processed milk products such as cheese, butter and eggs, processed meat products such as meat, salami, sausage and ham, and vegetables such as carrots, potatoes, asparagus and shiitake mushrooms.

  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.

(Method for measuring terminal amino group concentration)
0.5 g of sample is dissolved in 30 ml of phenol / ethanol = 4/1 (volume ratio), 5 ml of methanol is added, and an automatic titration apparatus (“COM-2000” manufactured by Hiranuma Seisakusho) is used with 0.01 N hydrochloric acid as a titrant. 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 titration was performed 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. The depolarization intensity method is a method of measuring the progress of crystallization of a resin using a device comprising a light source, a polarizing plate and a light receiving element, utilizing the phenomenon that light transmitted through the resin due to crystallization causes birefringence. is there. When an amorphous or molten specimen is crystallized, the amount of light transmitted through the polarizing plate changes in proportion to the progress of crystallization. The half crystallization time was defined as half the amount of transmitted light that changes under the measurement conditions, that is, half the time required for crystallization. Although the half crystallization time varies depending on the measurement temperature, in the following description, the shortest half crystallization time among the half crystallization times at each temperature is described as “half crystallization time”. Further, “Polymer Crystallization Rate Measuring Device Model MK-701” manufactured by Kotaki Manufacturing Co., Ltd. was used for measurement of crystallization time and semi-crystallization time.

(Polyamide resin synthesis conditions)
After the dicarboxylic acid is heated and melted at 170 ° C. in the reaction vessel, the metaxylylenediamine is added dropwise gradually and continuously so that the molar ratio with the dicarboxylic acid becomes 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. The obtained pellets were charged into a tumbler and subjected to solid phase polymerization under reduced pressure to obtain a polyamide resin having an adjusted molecular weight and MFR.

Example 1
(Synthesis of polyamide 1)
Metaxylylenediamine and sebacic acid were used in a molar ratio of 1: 1, and a polyamide resin was synthesized under the above synthesis conditions (hereinafter, the polyamide resin is referred to as polyamide 1). The temperature during solid phase polymerization was 160 ° C. Polyamide 1 has a Tg of 63 ° C., a melting point of 193 ° C., a terminal amino group concentration of 15.9 μeq / g, a terminal carboxyl group concentration of 70.3 μeq / g, a number average molecular weight of 23,000, a half-crystallization time of 154 seconds, and 240 ° C. MFR was 7.8 g / 10min. Moreover, when the unstretched film was produced with the obtained polyamide 1 alone and the oxygen permeability coefficient was determined, it was 1.58 cc · mm / (m ² · day · atm) (23 ° C. · 60% RH). .

  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.) “Kernel” is used as a polyolefin resin in a mixture of the obtained polyamide 1 and cobalt stearate (hereinafter referred to as cobalt stearate-containing polyamide 1A). KF380 ”, MFR 4.0 g / 10 min (measured in accordance with JIS K7210), 240 ° C. MFR 8.7 g / 10 min, 250 ° C. MFR 10.0 g / 10 min, hereinafter referred to as LLDPE), cobalt stearate Polyamide 1A: LLDPE = 35: 65 was melt kneaded at 240 ° C. to obtain oxygen-absorbing resin pellets A. Next, when a film made of a single layer oxygen-absorbing resin composition having a thickness of 30 μm was obtained using the pellets, the appearance of the film was good and the HAZE was 28%. The film is made into a 10 × 10 mm film, and the film is filled and sealed in a gas barrier bag made of an aluminum foil laminated film having a humidity of 30% and 100% in a bag together with 150 cc of air, respectively, at 40 ° C. After storage, the oxygen absorption amount for 7 days from the start of storage was investigated. In addition, the elongation percentage of the film after one month storage was investigated. These results are shown in Table 1.

(Example 2)
A film made of the oxygen-absorbing resin composition 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 1A: LLDPE = 55: 45. A storage test was performed. These results are shown in Table 1.

(Example 3)
A film made of the oxygen-absorbing resin composition 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 1A: LLDPE = 25: 75. A storage test was performed. These results are shown in Table 1.

(Comparative Example 1)
A film made of the oxygen-absorbing resin composition 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 1A: LLDPE = 80: 20. A storage test was performed. These results are shown in Table 1.

(Comparative Example 2)
A film made of the oxygen-absorbing resin composition was obtained 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 1A, and then the same storage test as in Example 1 was performed. Carried out. These results are shown in Table 1.

  As is clear from Examples 1 to 3, the oxygen-absorbing resin composition of the present invention exhibits good oxygen absorption performance under high humidity and low humidity, and retains film elasticity after oxygen absorption. The resin composition had good processability.

Example 4
Two-layer three-layer film 1 (thickness: 10 μm / 20 μm / 10 μm) having oxygen absorbing resin pellet A as a core layer and skin layer as LLDPE was corona discharge treated on one side at a width of 800 mm and 120 m / min. Made. The appearance of the obtained film was good, and HAZE was 28%. Nylon film A (product name: Toyo) using urethane-type dry laminate adhesive (product name: TM251 / CAT-RT88, hereinafter referred to as laminate adhesive) manufactured on the corona-treated surface side. N1202, manufactured by Spinning Co., Ltd., hereinafter referred to as ONy), aluminum foil and PET film A (product name; E5100 manufactured by Toyobo Co., Ltd.) are laminated, and PET film A (12) / laminating adhesive (3 ) / Aluminum foil (9) / Laminating adhesive (3) / ONy (15) / Laminating adhesive (3) / LLDPE (10) / Oxygen absorbing resin composition (20) / LLDPE (10) oxygen absorption A multilayer film was obtained. The numbers in parentheses mean the thickness of each layer (unit: μm). In the following examples, the same notation is used unless otherwise specified. Next, using this oxygen-absorbing multilayer film, a 15 × 20 cm three-side sealed bag was prepared, filled with 200 g of a vitamin C tablet having a water activity of 0.35, sealed, and stored at 40 ° C. When the oxygen concentration in the bag and the appearance after storage for 1 month were examined, the oxygen concentration in the bag was 0.1% or less, and the appearance of the vitamin C tablet was well maintained.

(Example 5)
Bleached kraft by extrusion lamination with low-density polyethylene (product name: “Mirason 18SP” manufactured by Mitsui Chemicals, Inc., hereinafter referred to as PE) using the two-type three-layer film 1 obtained in Example 4. Paper (basis weight 340 g / m ² ) / laminating adhesive (3) / alumina-deposited PET film (product name: “GL-AEH”, 12 manufactured by Toppan Printing Co., Ltd.) / Urethane anchor coating agent (Toyo Morton ( An oxygen-absorbing multilayer paper substrate of “EL-557A / B”, 0.5) / PE (20) / LLDPE (10) / oxygen-absorbing resin (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 sake, sealed, and stored at 40 ° C. The flavor after one month and the oxygen concentration in the paper container were 0.1% or less, and the flavor of sake was well maintained.

(Example 6)
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 PP1) Oxygen-absorbing resin pellets B were obtained in the same manner as in Example 1 except that was used. Subsequently, a two-layer three-layer film 2 (thickness: 15 μm / 30 μm / 15 μm) was produced in the same manner as in Example 4 except that the oxygen-absorbing resin pellet B was used as a core layer and the skin layer was replaced with PP1 instead of LLDPE. . The obtained film had a HAZE of 64%. Alumina-deposited PET (product name: “GL-AEH” manufactured by Toppan Printing Co., Ltd.) and ONy are laminated on the corona-treated surface side using a laminating adhesive, and alumina-deposited PET (12) / laminating adhesive ( 3) An oxygen-absorbing multilayer film of / ONy (15) / laminate adhesive (3) / PP1 (15) / oxygen-absorbing resin (30) / PP1 (15) was obtained. Next, using this oxygen-absorbing multilayer film, a 10 × 20 cm three-sided sealing bag is prepared, and a circular steaming port having a diameter of 2 mm is provided on a part of the bag, and the periphery of the steaming port is temporarily sealed with a label seal. I wore it. The bag was filled with curry containing carrot and meat, sealed, retort cooked at 124 ° C. for 30 minutes, heat sterilized, and stored at 40 ° C. 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, when the flavor of the curry and the color of the carrot were investigated, the appearance of the carrot was kept well, and the flavor of the curry was good.

(Comparative Example 3)
Iron powder having an average particle size 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-based oxygen-absorbing resin composition A. An iron-based oxygen-absorbing resin composition A was used as a core layer, and an attempt was made to produce a two-kind / three-layer film in the same manner as in Example 4. However, irregularities of iron powder occurred on the film surface, and no film was obtained. Therefore, an iron-based oxygen-absorbing resin composition A was extruded and laminated to 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 laminate film was laminated with bleached kraft paper as in Example 5, bleached kraft paper (basis weight 340 g / m ² ) / laminating adhesive (3) / alumina-deposited PET film (product name: manufactured by Toppan Printing Co., Ltd.) "GL-AEH", 12) / urethane anchor coating agent ("EL-557A / B" manufactured by Toyo Morton Co., Ltd., 0.5) / PE (20) / iron-based oxygen absorbing resin composition A (20) An attempt was made to produce a Gobeltop type paper container comprising an oxygen-absorbing multilayer paper base material of / LLDPE (40), 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 preservation test of sake was conducted in the same manner as in Example 5. However, an aldehyde odor was generated at the time of opening, and the flavor was significantly reduced.

(Comparative Example 4)
An iron-based oxygen-absorbing resin composition B was obtained in the same manner as in Comparative Example 3 except that PP1 was used instead of LLDPE. Subsequently, after producing the laminated film of iron-type oxygen absorption resin composition B (20) / PP1 (40), the oxygen absorption layer surface was subjected to corona discharge treatment. Hereinafter, in the same manner as in Example 6, alumina-deposited PET (product name: “GL-AEH”, 12 manufactured by Toppan Printing Co., Ltd.) / Laminating adhesive (3) / ONy (15) / adhesive (3) / An oxygen-absorbing multilayer film of iron-based oxygen-absorbing resin composition B (20) / PP1 (40) was obtained. As a result of performing the same test as in Example 6 using the obtained oxygen-absorbing multilayer film, the flavor was well maintained, but the contents were not visible, and when the microwave oven was heated, bubble-like unevenness was observed on the surface. Occurred.

  As is clear from Examples 5 to 6, the oxygen-absorbing resin composition of the present invention is excellent in processability into a paper container, and even when a steam inlet is attached during storage of an alcoholic beverage or cooking in a microwave oven. It became a good storage container. Moreover, it also has internal visibility, and the color tone of the contents could be confirmed.

  The present invention blends a specific polyamide resin and a transition metal with a polyolefin resin at a specific ratio, so that the oxygen absorption performance at low humidity and high humidity is excellent, the resin strength after storage is maintained, and the processability is further improved. And an oxygen-absorbing resin composition applicable to various containers and uses.

(Example 7)
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 200 ppm. Furthermore, LLDPE is used as a polyolefin resin in the obtained polyamide 1 and cobalt stearate mixture (hereinafter referred to as cobalt stearate-containing polyamide 1B), and a weight ratio of cobalt stearate-containing polyamide 1B: LLDPE = 40: 60. Then, it was melt kneaded at 240 ° C. to obtain oxygen-absorbing resin pellets C.

  The obtained oxygen-absorbing resin pellet C was used as an oxygen-absorbing resin layer, and LLDPE was used as an oxygen-permeable layer. A two-layer two-layer film 1 (thickness; oxygen-absorbing resin layer 20 μm / oxygen-permeable layer 10 μm) having a width of 800 mm, The surface of the oxygen-absorbing resin layer was subjected to corona discharge treatment at 130 m / min to produce a film roll. The film roll had no uneven thickness such as bumps, the appearance of the obtained film was good, and the HAZE was 72%. Using a laminating adhesive on the corona-treated surface side, ONy, aluminum foil and PET film A (product name: E5100 manufactured by Toyobo Co., Ltd.) are laminated, and PET film A (12) / laminating adhesive (3 ) / Aluminum foil (9) / adhesive for laminating (3) / ONy (15) / adhesive for laminating (3) / oxygen absorbing resin (20) / oxygen absorbing multilayer comprising LLDPE (10) A film was obtained. Next, using the oxygen-absorbing multilayer film, a 15 × 20 cm three-sided sealed bag with the LLDPE layer side as the inner surface was prepared, filled with 200 g of a powder seasoning “Dashi no Moto” having a water activity of 0.35, and sealed. Stored at 40 ° C. The oxygen concentration in the bag and the flavor of the powder seasoning were examined on the 7th day and after 1 month storage. These results are shown in Table 2.

(Example 8)
An oxygen-absorbing multilayer film was obtained in the same manner as in Example 7 except that the weight ratio at the time of melt kneading was changed to cobalt stearate-containing polyamide 1B: LLDPE = 55: 45. The same storage test as in No. 7 was performed. These results are shown in Table 2.

Example 9
An oxygen-absorbing multilayer film was obtained in the same manner as in Example 7 except that the weight ratio at the time of melt kneading was changed to cobalt stearate-containing polyamide 1B: LLDPE = 25: 75. The same storage test as in No. 7 was performed. These results are shown in Table 2.

(Example 10)
(Synthesis of polyamide 2)
Metaxylylenediamine, sebacic acid and adipic acid were used in a molar ratio of 10: 8: 2 to synthesize a polyamide resin (hereinafter, the polyamide resin is referred to as polyamide 2). The temperature during solid phase polymerization was 160 ° C. This polyamide 2 has a Tg of 68 ° C., a melting point of 188 ° C., a terminal amino group concentration of 16.2 μeq / g, a terminal carboxyl group concentration of 70.7 μeq / g, a semi-crystallization time of 144 seconds, a number average molecular weight of 23,000, and an MFR of 240 ° C. Was 7.6 g / 10 min. Moreover, when the unstretched film was produced with the obtained polyamide 2 single-piece | unit and the oxygen permeability coefficient was calculated | required, it was 1.18cc * mm / (m < ² > * day * atm) (23 degreeC * 60% RH). .

  Hereinafter, except that polyamide 2 was used in place of polyamide 1, an oxygen-absorbing multilayer film was obtained in the same manner as in Example 7, and then a three-side sealed bag was prepared, and the same storage test as in Example 7 was performed. . These results are shown in Table 2.

(Comparative Example 5)
After obtaining an oxygen-absorbing multilayer film in the same manner as in Example 7 except that the weight ratio at the time of melt-kneading was changed to cobalt stearate-containing polyamide 1B: LLDPE = 70: 30, a three-side sealed bag was prepared, and Example The same storage test as in No. 7 was performed. These results are shown in Table 2.

(Comparative Example 6)
An oxygen-absorbing multilayer film was obtained in the same manner as in Example 7 except that the weight ratio at the time of melt kneading was changed to cobalt stearate-containing polyamide 1B: LLDPE = 15: 85. The same storage test as in No. 7 was performed. These results are shown in Table 2.

(Example 11)
Two-layer three-layer film 3 (thickness: 10 μm / 20 μm / 10 μm) with oxygen-absorbing resin pellet C as a core layer and LLDPE as a skin layer is subjected to corona discharge treatment on one side at a width of 800 mm and 130 m / min. A film roll was prepared. The film roll was even better than the film rolls made in Examples 7-10.
Alumina-deposited PET film (product name: GL-AEH, 12 manufactured by Toppan Printing Co., Ltd.) / Adhesive for laminating (3) / ONy (15) by extrusion lamination with PE using two types of three-layer film 3 / Urethane anchor coating agent (EL-557A / B, 0.5 manufactured by Toyo Morton Co., Ltd.) / PE (20) / LLDPE (10) / Oxygen absorbing resin (20) / LLDPE (10) oxygen absorbing multilayer An oxygen-absorbing multilayer film consisting of When this film was processed into a self-supporting bag (130 × 175 × 35 mm) of two side films and one bottom film with the LLDPE layer side as the inner surface, the bag processability was good. The bag was filled with 150 g of asparagus together with a solution containing acetic acid at a rate 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. Ten filled and sealed bags were boiled at 90 ° C. for 30 minutes, stored at 40 ° C., and the asparagus flavor and the appearance of the self-supporting bag after one month were investigated. Asparagus was visible from the outside of the bag, the asparagus flavor and color tone were well maintained, and there was no abnormality in the appearance of the bag.

(Comparative Example 7)
An oxygen-absorbing resin pellet was prepared in the same manner as in Example 7 except that the weight ratio at the time of melt-kneading was changed to cobalt stearate-containing polyamide 1B: LLDPE = 80: 20. Similarly, an oxygen-absorbing multilayer film was produced and processed into a self-supporting bag. When 150 g of asparagus was filled with a solution containing acetic acid in the same manner as in Example 11, the sealing strength of the bag was low, and in particular, peeling between the oxygen permeable layer and the oxygen absorbing resin layer occurred. The filled bags were boiled at 90 ° C. for 30 minutes as they were, but 6 bags were broken. When the same storage test as in Example 11 was performed on the remaining bag, the flavor and color tone of asparagus were reduced. There was no abnormality in the appearance of the bag.

(Comparative Example 8)
Using the iron-based oxygen-absorbing resin composition A in place of the oxygen-absorbing resin pellet C, an attempt was made to produce a two-kind three-layer film in the same manner as in Example 11, but iron powder irregularities occurred on the film surface, A film was not obtained. Therefore, an iron-based oxygen-absorbing resin composition A as an oxygen-absorbing resin layer is extruded and laminated to a thickness of 20 μm on a film made of linear low-density polyethylene B (product name; LRW manufactured by Okamoto Co., Ltd.) having a thickness of 40 μm. Then, a laminate film in which the oxygen-absorbing resin layer surface was subjected to corona discharge treatment was obtained. The laminate film was laminated in the same manner as in Example 11, and alumina-deposited PET film (product name: GL-AEH, 12 manufactured by Toppan Printing Co., Ltd.) / Laminating adhesive (3) / ONy (15) / urethane anchor Coating agent (product name; manufactured by Toyo Morton Co., Ltd. EL-557A / B, 0.5) / PE (20) / iron-based oxygen-absorbing resin composition A (20) / linear low-density polyethylene B (40) The iron-based oxygen-absorbing multilayer was prepared and processed into a self-supporting bag in the same manner as in Example 11. As in Example 11, an attempt was made to fill a total of 150 g of asparagus with a solution containing acetic acid. As a result, the bag opening property was poor, and the contents spilled out and could not be filled in several bags. Furthermore, after the boil treatment in the same manner as in Example 11, a storage test was conducted. However, since asparagus was not visible from the outside of the bag, the bag was opened. Although the flavor and color tone of asparagus were well maintained, the bag appearance was uneven and some delamination occurred.

Example 12
Oxygen-absorbing resin pellets were prepared in the same manner as in Example 7 except that polyamide 2 was used instead of polyamide 1 and PP1 was used instead of LLDPE. Subsequently, a two-type three-layer film 4 (thickness: 15 μm / 30 μm / 15 μm) was produced in the same manner as in Example 11 except that LLDPE was changed to PP1. The appearance shape of the produced film roll and the appearance of the film were good. HAZE was 64%. Using a laminating adhesive on the corona-treated surface side, ONy and silica-deposited PET film (product name: Tech Barrier TXR manufactured by Mitsubishi Plastics, Inc.) are laminated, and silica-deposited PET film (12) / laminating adhesive ( An oxygen-absorbing multilayer film comprising an oxygen-absorbing multilayer body of 3) / ONy (15) / laminating adhesive (3) / PP1 (15) / oxygen-absorbing resin (30) / PP1 (15) was obtained. Using this oxygen-absorbing multilayer film, the PP1 layer side is used as the inner surface to produce a 10 x 20 cm three-sided sealing bag, and a circular steaming port with a diameter of 2 mm is provided on a part of the bag, and the steaming port is label-sealed. I temporarily attached around. The bag was filled with 100 g of risotto containing fish and shellfish such as squid, crab and shellfish, sealed, cooked at 124 ° C. for 30 minutes, sterilized by heating, and stored at 40 ° C. 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 risotto and the color of the fish and shellfish such as crabs were examined. The appearance of the fish and shellfish was well maintained and the flavor of the risotto was good.

(Comparative Example 9)
Except for the cobalt stearate-containing polyamide 1B: PP1 = 10: 90, an oxygen-absorbing resin pellet was prepared in the same manner as in Example 7, and a three-side sealed bag was prepared in the same manner as in Example 12 using the pellet. The risotto was stored and cooked. Although there was no abnormality in the bags after cooking the range, the color of fish shellfish such as crabs and the flavor of risotto were decreasing.

(Example 13)
Oxygen-absorbing resin layer 30 μm composed of oxygen-absorbing resin pellets C and olefin polymer alloy (product name: VMX / X150F manufactured by Mitsubishi Chemical Corporation, MFR 3.5 g / 10 min (measured according to JIS K7210), 240 ° C. An oxygen permeable layer 30 μm having a melt viscosity of 7.9 g / 10 min was laminated to prepare a two-kind two-layer film 2. Subsequently, using a laminating adhesive, 15 μm of an ethylene-vinyl alcohol copolymer layer and 15 μm of a nylon film B (product name: “N1102” manufactured by Toyobo Co., Ltd.) are laminated to form a nylon film B (15) / Adhesive for laminate (3) / Ethylene-vinyl alcohol copolymer film A (Eval EF-XL, 15 manufactured by Kuraray Co., Ltd.) / Adhesive for laminate (3) / Oxygen absorbing resin (30) / olefin polymer alloy An oxygen-absorbing multilayer film comprising the oxygen-absorbing multilayer body of (30) was obtained. The appearance of the film was good.

  Next, PP1 (400) / maleic anhydride modified polypropylene (product name: Admer QF500, 15 manufactured by Mitsui Chemicals, Inc.) / Ethylene-vinyl alcohol copolymer B (product name: Eval L104B, 40 manufactured by Kuraray Co., Ltd.) ) / Maleic anhydride modified polypropylene (product name; same as above, 15) / PP1 (400) sheet was molded into a 70 cc cup with a drawing ratio of 2.5. The cup was filled with orange jelly, and the produced oxygen-absorbing multilayer film was sealed by using it as a cover material with the nylon film B layer side as the outer surface. The color tone of the contents was visible from the lid. The sealed container was heat-treated at 85 ° C. for 30 minutes and stored at 40 ° C. for 1 month. One month later, the container was opened, and it did not become a double lid. The opening was good, and the flavor and color of the contents were well maintained.

(Example 14)
Using an oxygen-absorbing multilayer film obtained in the same manner as in Example 13 and a 70 cc cup, hydrogen peroxide sterilization was performed by immersion. There was no abnormality in the oxygen-absorbing multilayer film during sterilization. The cup was hot-filled with strawberry jam kept at 80 ° C., and the oxygen-absorbing multilayer film was sealed as a lid with the nylon film B layer side outside. The sealed container was stored at 40 ° C. for 1 month. One month later, when the contents were visually confirmed from the lid material, the color tone was kept good. When the lid was opened, the opening was good and the flavor of the contents was well maintained without becoming a double lid.

(Comparative Example 10)
When an iron-based oxygen-absorbing multilayer body having an iron-based oxygen-absorbing resin layer obtained in the same manner as in Comparative Example 8 was sterilized with hydrogen peroxide by the same method as in Example 14, bubbles were generated in the hydrogen peroxide, and sterilization was performed. Could not continue.

  As is clear from Examples 7 to 14, the oxygen-absorbing multilayer body of the present invention is excellent in oxygen absorption performance, workability, and strength, and can be boiled and retorted, and uses an iron-based oxygen absorbent. It can be applied to foods and the like that cannot be stored with an oxygen-absorbing multilayer, can be sterilized with hydrogen peroxide, and can be a good storage container even if a fume hood is attached during microwave cooking. Moreover, it also has internal visibility, can confirm the color tone of the contents, etc., and can also be used for a container lid.

  The present invention provides a multilayer body having an oxygen-absorbing resin layer obtained by blending a specific polyamide and a transition metal catalyst with a polyolefin resin at a specific ratio, thereby providing excellent oxygen absorption performance at low humidity and high humidity. The present invention relates to an oxygen-absorbing multilayer body that retains resin strength, has excellent processability, and can be applied to various containers and uses.

(Example 15)
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, polypropylene A (product name; manufactured by Nippon Polypro Co., Ltd., Novatec PP EG7F, MFR1) was used as a polyolefin resin in a mixture of the obtained polyamide 1 and cobalt stearate (hereinafter referred to as cobalt stearate-containing polyamide 1C). .3 g / 10 min (measured according to JIS K7210), MFR 8.2 g / 10 min at 240 ° C., MFR 9.8 g / 10 min at 250 ° C., hereinafter referred to as PP2), and cobalt stearate-containing polyamide 1C: PP2 = Oxygen-absorbing resin pellet D was obtained by melt-kneading at 240 ° C. with a twin-screw extruder so as to be 35:65.

  Next, using a four-kind 6-layer multi-layer sheet forming apparatus comprising a first to a fourth extruder, a feed block, a T die, a cooling roll, and a sheet take-up machine, the first extruder; PP2, the second extrusion Machine; oxygen-absorbing resin pellet D, third extruder; ethylene-vinyl alcohol copolymer C (product name; Eval L171B manufactured by Kuraray), and fourth extruder; polypropylene adhesive resin (product name: Mitsubishi Chemical ( Co., Ltd. Modic P604V) was extruded to obtain an oxygen-absorbing multilayer sheet. The multilayer sheet is composed of PP2 (80) / oxygen absorbing resin (100) / adhesive layer (15) / ethylene-vinyl alcohol copolymer C (30) / adhesive layer (15) / PP2 (250) from the inner layer. Met. Further, the multilayer sheet obtained by coextrusion was a multilayer sheet having a good appearance without thickness unevenness.

Next, the obtained multilayer sheet was thermoformed into a tray-like container (inner volume 350 cc, surface area 200 cm ² ) with the inner layer inside using a vacuum forming machine. The obtained oxygen-absorbing multilayer container had good appearance with no thickness unevenness. This container was sterilized by ultraviolet sterilization, and 200 g of aseptic cooked rice immediately after cooking was placed in the container, and oxygen in the container was replaced with nitrogen gas to adjust the oxygen concentration to 0.5%. Next, PET film B (product name: E5102 manufactured by Toyobo Co., Ltd.), MXD6-based multilayer coextruded nylon film (product name: Super Neal SP-R manufactured by Mitsubishi Plastics), unstretched polypropylene film (product name; Gas barrier film (PET film B (12) / Laminating adhesive (3) / MXD6 multilayer coextruded nylon film (15) / Laminating adhesive) obtained by dry laminating Aroma UT21, manufactured by Okamoto Co., Ltd. Agent (3) / Unstretched polypropylene film (60)) was used as a top film, and after sterilization with ultraviolet rays as in the case of the container, the container was sealed and stored under conditions of 40 ° C. and 50% RH. The container was opened after measuring the oxygen concentration in the container 3 months after the start of storage, and the flavor of the cooked rice and the strength of the oxygen absorbing container were confirmed. The results are shown in Table 3.

(Example 16)
Except that the weight ratio at the time of melt kneading was changed to cobalt stearate-containing polyamide 1C: PP2 = 55: 45, an oxygen-absorbing multilayer sheet was obtained in the same manner as in Example 15 and then an oxygen-absorbing multilayer container was prepared and carried out. The same storage test as in Example 15 was performed. The results are shown in Table 3.

(Example 17)
Except that the weight ratio at the time of melt-kneading was changed to cobalt stearate-containing polyamide 1C: PP2 = 20: 80, after obtaining an oxygen-absorbing multilayer sheet in the same manner as in Example 15, an oxygen-absorbing multilayer container was prepared and carried out. The same storage test as in Example 15 was performed. The results are shown in Table 3.

(Example 18)
An oxygen-absorbing multilayer sheet was obtained in the same manner as in Example 15 except that polyamide 2 was used in place of polyamide 1, and then an oxygen-absorbing multilayer container was prepared and the same storage test as in Example 15 was performed. The results are shown in Table 3.

(Comparative Example 11)
Iron powder having an average particle diameter of 20 μm and calcium chloride were mixed at a ratio of 100: 1, and this and PP2 were kneaded at a weight ratio of 30:70 to obtain an iron-based oxygen-absorbing resin composition B. Subsequently, an iron-based oxygen-absorbing multilayer sheet was produced in the same manner as in Example 15 except that the iron-based oxygen-absorbing resin composition B was used for the oxygen-absorbing resin layer. The multilayer sheet is composed of PP2 (80) / iron-based oxygen absorbing resin B (100) / adhesive layer (15) / ethylene-vinyl alcohol copolymer C (30) / adhesive layer (15) / PP2 from the inner layer. (250). The obtained iron-based oxygen-absorbing multilayer sheet was thermoformed to produce a tray-like container, but it was difficult to process because a drawdown occurred. Moreover, since the produced container used iron powder, it was opaque and the external appearance was bad because of unevenness caused by the iron powder. However, since a container having an appearance was obtained, the same storage test as in Example 15 was performed. The results are shown in Table 3.

  As is clear from Examples 15-18, the oxygen-absorbing multilayer container of the present invention exhibits good moldability and oxygen-absorbing performance, is transparent, and can retain the strength of the container even after oxygen absorption. is there.

(Example 19)
Cobalt stearate-containing polyamide 1C, polypropylene B (product name; manufactured by Nippon Polypro Co., Ltd., Novatec PP FW4BT, MFR 6.5 g / 10 min (measured in accordance with JIS K7210), 240 ° C. MFR8. 3 g / 10 min, MFR 10.0 g / 10 min at 250 ° C., hereinafter referred to as PP3), and melt-kneaded at 240 ° C. in a weight ratio of cobalt stearate-containing polyamide 1C: PP3 = 35: 65 to absorb oxygen Resin pellet E was obtained. Next, a two-kind three-layer film 5 (thickness: 10 μm / 10 μm / 10 μm) with oxygen-absorbing resin pellet E as the core layer and PP3 as the skin layer was subjected to corona discharge treatment on one side with a width of 800 mm and 100 m / min. Made. The appearance of the obtained film was good, and HAZE was 10%.

  This oxygen-absorbing film and a 200 μm polypropylene sheet (product name: NS3451 manufactured by Sumitomo Bakelite) were dry-laminated using a gas barrier adhesive (product name: Maxive manufactured by Mitsubishi Gas Chemical Co., Ltd.), and PP3 ( 10) / Oxygen-absorbing resin (10) / PP3 (10) / gas barrier adhesive (3) / polypropylene sheet (200), after preparing the oxygen-absorbing multilayer sheet, Vacuum forming was performed to form a press-through pack pocket (diameter 12 mm, depth 5 mm). Further, 25 μm aluminum foil is coated with a urethane anchor coating agent (product name: A3210 manufactured by Mitsui Chemicals Polyurethane Co., Ltd.), and polypropylene C (product name: F329RA manufactured by Prime Polymer Co., Ltd.) as a heat seal material is coated with 25 μm. Extrusion coating was performed at a thickness to obtain an aluminum foil laminate of aluminum foil (25) / anchor coating agent (1) / polypropylene C (25). The pocket was filled with 2 g of a vitamin C tablet having a water activity of 0.35, the aluminum foil laminate was heat-sealed and sealed, and stored at 40 ° C. When the oxygen concentration in the bag and the appearance after storage for 1 month were investigated, the oxygen concentration in the pocket was 0.1% or less, and the appearance of the vitamin C tablet was well maintained.

(Example 20)
In the same manner as in Example 15, an oxygen-absorbing multilayer sheet was produced. The multilayer sheet is composed of PP2 (90) / oxygen absorbing resin (80) / adhesive layer (15) / ethylene-vinyl alcohol copolymer C (30) / adhesive layer (15) / PP2 (250) from the inner layer. Met. Next, the multilayer sheet was thermoformed into a cup-shaped container (inner volume: 100 cc, surface area: 96 cm ² ) with the inner layer inside, using a vacuum forming machine. After spraying the container with mist of hydrogen peroxide, it was dried with hot air and sterilized. Thereafter, orange jam was filled, and the gas barrier film obtained in the same manner as in Example 15 was similarly sterilized with hydrogen peroxide, sealed using a top film, and stored at 40 ° C. The oxygen concentration in the container after storage for 1 month was 0.1% or less, and the orange jam retained the flavor.

(Comparative Example 12)
In the same manner as in Comparative Example 11, an iron-based oxygen absorbing multilayer sheet was produced. The multilayer sheet is composed of PP2 (90) / iron-based oxygen-absorbing resin B layer (80) / adhesive layer (15) / ethylene-vinyl alcohol copolymer C (30) / adhesive layer (15) / from the inner layer. PP2 (250). Next, the iron-based oxygen-absorbing multilayer sheet was thermoformed to try to produce a cup-like container similar to that in Example 20, but it was difficult to process because drawdown occurred. However, since a container having an appearance was obtained, when atomized hydrogen peroxide was sprayed on the container, the iron powder exposed on the container end surface reacted with hydrogen peroxide, and sterilization was difficult. The iron powder on the end face was rusted after drying at.

  The present invention kneads a polyolefin resin with a specific polyamide resin and transition metal at a specific ratio, so that the oxygen absorption performance at low humidity and high humidity is excellent, the resin strength after storage is maintained, and the processability is further improved. The present invention relates to an oxygen-absorbing multilayer container that is formed by thermoforming an oxygen-absorbing multilayer body that is excellent in and applicable to various containers and uses.

Claims (3)

  An oxygen-absorbing resin composition comprising at least a polyolefin resin, a transition metal catalyst, and a polyamide resin, wherein the polyamide resin has a melting point of 200 ° C. or lower, a glass transition temperature of 80 ° C. or lower, and the transition metal catalyst and the polyamide An oxygen-absorbing resin composition having a total resin content of 20 to 60% by weight.   An oxygen-absorbing multilayer body comprising at least three layers of an oxygen-permeable layer made of a thermoplastic resin, an oxygen-absorbing resin layer containing the oxygen-absorbing resin composition according to claim 1 and a gas barrier layer made of a gas-barrier substance in this order.   An oxygen-absorbing multilayer container obtained by thermoforming an oxygen-permeable layer of the oxygen-absorbing multilayer body according to claim 2 as an inside.