JP2011094021A - Oxygen absorbing resin composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resin composition excellent in oxygen absorbing performance. <P>SOLUTION: The oxygen absorbing resin composition contains at least a transition metal catalyst and a polyamide resin, wherein the polyamide resin is obtained by polycondensation of at least three components of metaxylene diamine, adipic acid and sebacic acid in molar ratios of (metaxylene diamine):(adipic acid):(sebacic acid)=(0.985 to 0.997):(0.3 to 0.7):(0.7 to 0.3), and the polyamide resin has terminal amino group concentration of 30 μeq/g or lower. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an oxygen-absorbing resin composition that exhibits excellent oxygen absorption performance and does not generate odor.

  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. 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).

  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.

  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. In a system in which transition metal is mixed with MXD6, In order to use the oxygen-absorbing resin composition as an oxygen-absorbing resin composition and to preserve the material to be stored satisfactorily, the oxygen-absorbing ability is low.

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 the oxygen absorption performance which solved the said trouble.

  The inventors have found that an oxygen-absorbing resin composition excellent in oxygen-absorbing performance can be obtained by blending a specific polyamide and a transition metal.

  That is, the present invention provides an oxygen-absorbing resin composition containing at least a transition metal catalyst and a polyamide resin, wherein the polyamide resin contains at least three components of metaxylylenediamine, adipic acid and sebacic acid. The terminal amino group concentration formed by polycondensation at a molar ratio of amine: adipic acid: sebacic acid = 0.985-0.997: 0.3-0.7: 0.7-0.3 is 30 μeq / g or less. An oxygen-absorbing resin composition characterized by being a polyamide resin.

  According to the present invention, an oxygen-absorbing resin composition having high oxygen-absorbing performance can be provided.

  The oxygen-absorbing resin composition of the present invention comprises at least three components of metaxylylenediamine, adipic acid and sebacic acid, metaxylylenediamine: adipic acid: sebacic acid = 0.985 to 0.997: 0.7. A polyamide resin having a terminal amino group concentration of 30 μeq / g or less formed by polycondensation at a molar ratio of ˜0.3: 0.3 to 0.7 (hereinafter, the polyamide resin is particularly referred to as “polyamide resin A”) It is a resin composition containing a transition metal catalyst. Hereinafter, the polyamide resin A and the transition metal catalyst will be described in detail.

  The polyamide resin A in the present invention is obtained by polycondensation reaction of metaxylylenediamine with adipic acid and sebacic acid, and the molar ratio at that time is metaxylylenediamine: adipic acid: sebacic acid = 0.985-0. .997: 0.3 to 0.7: 0.7 to 0.3, preferably 0.985 to 0.997: 0.4 to 0.6: 0.6 to 0.4. The polycondensation reaction of metaxylylenediamine with adipic acid and sebacic acid can proceed by melt polymerization for melting them, solid phase polymerization for heating polyamide resin pellets, etc. under reduced pressure. In addition, in the polycondensation reaction, in addition to metaxylylenediamine, adipic acid, and sebacic acid, other diamines, various aliphatic dicarboxylic acids, and aromatic dicarboxylic acids are incorporated as copolymer components to the extent that they do not affect performance. But you can.

  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 metaxylylenediamine, adipic acid and sebacic acid at the above molar ratio. A terminal amino group concentration of 25 μeq / g or less is preferable because oxygen absorption performance is improved, and 20 μeq / g or less is particularly preferable. Moreover, when the terminal amino group concentration is higher than 30 μeq / g, good oxygen absorption performance cannot be obtained. 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) A method of adjusting the molar ratio of metaxylylenediamine, adipic acid and sebacic acid to carry out polycondensation 2) A method of reacting a polyamide resin with a carboxylic acid to seal a terminal amino group 3) A polyamide resin It is preferable to carry out a method such as a solid phase polymerization method, and these methods can be carried out alone or in combination. Hereinafter, these methods will be described.

  1) In the method of carrying out polycondensation by adjusting the molar ratio of metaxylylenediamine, adipic acid and sebacic acid, adipic acid and sebacic acid are used in excess relative to metaxylylenediamine. The molar ratio of metaxylylenediamine, adipic acid and sebacic acid (metaxylylenediamine / (adipic acid and sebacic acid)) is preferably 0.985 to 0.997, particularly 0.988 to It is preferable to use 0.995. When 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 more, and is preferably lower by 10 ° C. or more than the melting point of the polyamide resin, more preferably 15 ° C. 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 a low crystallinity with a half-crystallization time of 150 seconds or more, or those having no melting point peak when the melting point is measured 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.

  In view of processability and oxygen absorption performance, polyamide resin A preferably has a low melting point or glass transition temperature (hereinafter referred to as Tg). 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), higher oxygen absorption performance is obtained when polyamide resin A and polyolefin are blended. It is done.

  The melt flow rate of polyamide resin A (hereinafter referred to as MFR) is preferably 3 to 20 g / 10 min at 200 ° C., 4 to 25 g / 10 min at 240 ° C. in view of its processability. . By making MFR into the above range, it is possible to obtain a processed product such as a film or sheet having no problem in appearance using the polyamide resin A. 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 metaxylylenediamine with adipic acid and sebacic acid is preferably synthesized by a method that undergoes two stages of solid-phase polymerization after melt polymerization. The number average molecular weight of the polyamide resin A is preferably 15000 to 27000, particularly preferably 17000 to 26000.

  The polyamide resin A of the present invention may be blended with a polyester resin such as polyethylene terephthalate (hereinafter referred to as PET) resin, a nylon resin, a polyolefin resin, or the like. A composition obtained by blending with these various resins can be formed into a bottle, a film, or a sheet to form an oxygen-barrier multilayer container. Further, an oxygen-absorbing multilayer container can be formed by further blending a transition metal catalyst.

  When the polyamide resin A of the present invention is blended with a polyester resin, nylon resin, polyolefin resin or the like, 5 to 60 wt% of the polyamide resin A of the present invention can be added and used in various molded containers. As the nylon resin, crystalline nylon such as nylon 6 or nylon 66 or amorphous nylon can be blended.

Polyolefin resins include 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, polymethylpentene, propylene homopolymer, propylene -Polypropylenes such as ethylene block copolymer and 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. High-density polyethylene, medium-density polyethylene, low-density polyethylene, linear low-density polyethylene, polyethylene using a metallocene catalyst, propylene-ethylene block copolymer, propylene-ethylene random due to oxygen absorption performance and film processability Various polypropylenes such as copolymers 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.

  The polyamide resin A of the present invention and various resins used for blending include coloring pigments such as titanium oxide, additives such as antioxidants, slip agents, antistatic agents, stabilizers, calcium carbonate, clay, A filler such as mica and silica, a deodorant, and 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 blended with various resins when blended with various resins. 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.

  It is preferable that the polyamide resin A to which the transition metal catalyst is added and the polyolefin resin exemplified above are mixed 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, and particularly preferably 25 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 oxygen-absorbing resin composition of the present invention can be used as an oxygen absorbent material as a resin composition. That is, an oxygen-absorbing resin composition in the form of pellets or sheets 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 provide a space | gap between the island-like layers of the polyamide resin A and various resin. Nylon 6, PET, high-density polyethylene, or the like is preferably used as various resins for stretching.

  In addition, the oxygen-absorbing resin composition of the present invention is a film-like or sheet-like, comprising at least a sealant layer containing a polyolefin resin, an oxygen-absorbing layer containing an oxygen-absorbing resin composition, and a gas barrier layer containing a gas-barrier substance. It is preferable to use it as an oxygen-absorbing multilayer body. At that time, the above-mentioned various resins may be blended with the oxygen-absorbing resin composition.

  In this case, the sealant layer is selected from the polyolefin resins exemplified above, and among these, various polyethylenes and various polypropylenes are preferably used. Examples of the gas barrier material include various vapor-deposited 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 and other metal foils, A known gas barrier material is used.

  Although there is no restriction | limiting in particular in the thickness of the oxygen absorption resin composition at the time of using as 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, the oxygen-absorbing resin composition can further improve the performance of absorbing oxygen and can 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 layer containing the oxygen-absorbing resin composition, but is preferably 2 to 50 μm, particularly preferably 5 to 30 μm. In this case, compared with the case where the thickness is out of the above range, the oxygen absorbing rate of the oxygen absorbing resin composition can be further increased, and the workability can be prevented from being impaired. When processing into a film or sheet, considering the workability, the thickness ratio of the sealant layer and the oxygen absorbing layer is preferably 1: 0.5 to 1: 3, and 1: 1 to 1: 2.5. Particularly preferred.

  In addition, when considering the processability when forming a multilayer body, it is preferable to interpose an intermediate layer containing a polyolefin resin between a gas barrier layer containing a gas barrier substance and an oxygen absorbing layer containing an oxygen absorbing resin composition. The thickness of the intermediate layer is preferably substantially the same as the thickness of the sealant layer from the viewpoint of workability. In this case, considering variations due to processing, the thickness is the same if the thickness ratio is within ± 10%.

  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 resin composition can absorb oxygen regardless of the presence or absence of moisture in the preserved product, 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 resin composition obtained in 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 resin compositions using iron powder. .

  Other items to be preserved include processed rice such as polished rice, cooked rice, red rice and rice cake, cooked foods such as soup, stew and curry, confectionery such as fruit, sheep, pudding, cake and buns, tuna and fish shellfish. Fish 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.

(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 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. In other words, when light is irradiated to the molten sample pellet, the amount of light transmission decreases with the crystallization of the sample pellet, and the time when the amount of transmission reaches the top is regarded as crystallization. The time when the amount reached 50% 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 synthesis conditions using metaxylylenediamine: sebacic acid: adipic acid in a molar ratio of 0.992: 0.5: 0.5. (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. In Polyamide 1, no DSC peak was observed for Tg of 69 ° C. and melting point. The half crystallization time was 2000 seconds or more, the terminal amino group concentration was 18.5 μeq / g, the terminal carboxyl group concentration was 91.6 μeq / g, the number average molecular weight was 23200, and the MFR at 240 ° C. was 12.0 g / 10 min. Moreover, when the unstretched film was produced with the obtained polyamide 1 alone and the oxygen transmission coefficient was determined, it was 0.35 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. Further, a mixture of the obtained polyamide and cobalt stearate (hereinafter referred to as cobalt stearate-containing polyamide 1) was melted at 240 ° C. to obtain a film made of a single layer oxygen-absorbing resin composition having a thickness of 50 μm. It was. The film was made into a 10 × 10 mm film, and the film was filled and sealed with two 100 cc air barrier bags made of aluminum foil laminated films with a humidity of 30% and 100% in the bag, respectively, at 23 ° C. After storage, the oxygen absorption amount for 7 days from the start of storage was investigated. These results are shown in Table 2.

(Example 2)
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 0.993: 0.35: 0.65. (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 79 ° C., a melting point of 187 ° C., a semicrystallization time of 2000 seconds or more, a terminal amino group concentration of 17.5 μeq / g, a terminal carboxyl group concentration of 68.6 μeq / g, and a number average molecular weight of 19,200 and 240 ° C. MFR was 24.0 g / 10min. 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 0.28cc * mm / (m < ² > * day * atm) (23 degreeC * 60% RH). . Thereafter, a film was produced in the same manner as in Example 1, and the oxygen absorption amount of the film was measured. These results are shown in Table 2.

(Example 3)
Metaxylylenediamine: sebacic acid: adipic acid was used in a molar ratio of 0.991: 0.65: 0.35, and only melt polymerization was performed under the above synthesis conditions. In order to reduce the terminal amino group concentration to the obtained synthetic product, 0.5 wt% anhydrous phthalate was added and melt kneaded at 230 ° C. in a twin screw extruder to seal the terminal amino group (hereinafter, the polyamide resin was sealed). Polyamide 3). The dropping time was 2 hours, and the reaction time for melt polymerization was 1 hour. Polyamide 3 had a Tg of 67 ° C., and no DSC peak was observed for the melting point. The half crystallization time was 2000 seconds or more, the terminal amino group concentration was 15.6 μeq / g, the terminal carboxyl group concentration was 71.6 μeq / g, the number average molecular weight was 19,800, and the MFR at 240 ° C. was 23.0 g / 10 minutes. . Moreover, when the unstretched film was produced with the obtained polyamide 3 single-piece | unit and the oxygen permeability coefficient was calculated | required, it was 0.54 cc * mm / (m < ² > * day * atm) (23 degreeC * 60% RH). . Thereafter, a film was produced in the same manner as in Example 1, and the oxygen absorption amount of the film was measured. These results are shown in Table 2.

(Comparative Example 1)
A metaxylylenediamine and adipic acid were used in a molar ratio of 0.994: 1, and a polyamide resin was synthesized by melt polymerization and solid phase polymerization under the above synthesis conditions (hereinafter, the polyamide resin was 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 6 hours. Polyamide 4 had a Tg of 85 ° C., a melting point of 237 ° C., a half crystallization time of 25 seconds, a terminal amino group concentration of 19.6 μeq / g, a terminal carboxyl group concentration of 71.2 μeq / g, and a number average molecular weight of 23,000. Moreover, since it was near melting | fusing point at 240 degreeC, MFR was not measurable, MFR of 250 degreeC was measured, and MFR in 250 degreeC was 14.4 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 0.09 cc · mm / (m ² · day · atm) (23 ° C. · 60% RH). there were. Thereafter, a film was produced in the same manner as in Example 1, and the oxygen absorption amount of the film was measured. These results are shown in Table 2.

(Comparative Example 2)
Metaxylylenediamine: sebacic acid: adipic acid was used in a molar ratio of 0.992: 0.8: 0.2, and only a melt polymerization was performed under the above synthesis conditions to synthesize a polyamide resin (hereinafter, The polyamide resin is referred to as polyamide 5). The dropping time was 2 hours, and the reaction time for melt polymerization was 1 hour. Polyamide 5 has a Tg of 63 ° C., a melting point of 172 ° C., a semicrystallization time of 1380 seconds, a terminal amino group concentration of 39.6 μeq / g, a terminal carboxyl group concentration of 73.2 μeq / g, and a number average molecular weight of 19800 and 240 ° C. The MFR was 28 g / 10 minutes. Moreover, when an unstretched film was produced with the obtained polyamide 5 alone and its oxygen permeability coefficient was determined, it was 0.94 cc · mm / (m ² · day · atm) (23 ° C. · 60% RH). . Thereafter, a film was produced in the same manner as in Example 1, and the oxygen absorption amount of the film was measured. These results are shown in Table 2.

(Comparative Example 3)
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: 0.2: 0.8. (Hereinafter, the polyamide resin is referred to as polyamide 6). 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 180 ° C., and the polymerization time was 3 hours. Polyamide 6 has a Tg of 81 ° C., a melting point of 214 ° C., and a half crystallization time of 110 seconds, a terminal amino group concentration of 22.1 μeq / g, a terminal carboxyl group concentration of 71.6 μeq / g, a number average molecular weight of 22000, 240 ° C. MFR was 14.0 g / 10min. Moreover, when an unstretched film was prepared from the obtained polyamide 6 alone and its oxygen transmission coefficient was determined, it was 0.12 cc · mm / (m ² · day · atm) (23 ° C. · 60% RH). . Thereafter, a film was produced in the same manner as in Example 1, and the oxygen absorption amount of the film was measured. These results are shown in Table 2.

(Comparative Example 4)
A metaxylylenediamine: sebacic acid: adipic acid was used at a molar ratio of 1.0: 0.4: 0.6, and only a melt polymerization was performed under the above synthesis conditions to synthesize a polyamide resin (hereinafter, The polyamide resin is referred to as polyamide 7). The dropping time was 2 hours, and the reaction time for melt polymerization was 1 hour. Polyamide 7 has a Tg of 77 ° C., a melting point of 184 ° C., a semicrystallization time of 2000 seconds or more, a terminal amino group concentration of 45.1 μeq / g, a terminal carboxyl group concentration of 77.6 μeq / g, and a number average molecular weight of 19800, 240 ° C. The MFR was 28.0 g / 10 min. 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). . Thereafter, a film was produced in the same manner as in Example 1, and the oxygen absorption amount of the film was measured. These results are shown in Table 2.

  As is clear from Examples 1 to 3, the oxygen-absorbing resin composition of the present invention was a resin composition that showed good oxygen-absorbing performance under high humidity and low humidity.

Example 4
Cobalt stearate-containing polyamide 1 was used, and polyvinylidene chloride / maleic anhydride-modified polyethylene / cobalt stearate-containing polyamide 1 / maleic anhydride-modified polyethylene / low density polyethylene = 240/10/30/10/20 μm in thickness. A push sheet was created. The sheet was heated with an unwinding heater and then pressed with polyethylene inside, filled with vitamin C tablets (water activity 0.32), and a low-density polyethylene / aluminum foil film was laminated and sealed. It was stored at 40 ° C. for 1 month, and the color tone of the vitamin C tablet was observed from the outside of the container. The color tone of vitamin C was well maintained.

(Example 5)
Cobalt stearate-containing polyamide 1 as polyolefin resin, linear low density polyethylene (product name: Novatec LL UF641, manufactured by Nippon Polyethylene Co., Ltd., MFR 2.1 g / 10 min (measured according to JIS K7210), 240 ° C. MFR 4.4 g / 10 min, MFR 5.2 g / 10 min at 250 ° C., hereinafter referred to as LLDPE) and maleic anhydride modified polyethylene (product name; Modic M545 manufactured by Mitsubishi Chemical Co., Ltd., MFR 6.0 g / min (according to JIS K7210) Measurement) and hereinafter referred to as MAPE) was melt kneaded at 240 ° C. in a weight ratio of cobalt stearate-containing polyamide 1: LLDPE: MAPE = 40: 55: 5 to obtain oxygen-absorbing resin pellets A.

  The obtained oxygen-absorbing resin pellet A was used as an oxygen-absorbing resin layer, and LLDPE was used as a sealant layer and an intermediate layer. The intermediate layer surface was subjected to corona discharge treatment at a width of 800 mm and 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 24%. Low density polyethylene (NUC8008 manufactured by Nihon Unicar Co., Ltd.) is used as an adhesive resin for extrusion lamination, and the aluminum foil surface side of PET / adhesive / aluminum foil and the corona-treated surface side of the two-kind / three-layer film 1 are laminated. (12) / Adhesive (3) / Aluminum Foil (7) / Adhesive Resin (20) / LLDPE (10) / Oxygen Absorbing Resin (10) / Oxygen Absorbing Multilayer Film Consisting of LLDPE (10) Got. The numbers in parentheses mean the thickness of each layer (unit: μm). Using this oxygen-absorbing multilayer film, a 5 × 10 cm gusset bag was produced with the LLDPE layer side as the inner surface, filled with 50 g of chestnut sheep and sealed. Thereafter, the specimen was stored at 40 ° C. and 100% RH. The container was opened after storage for 1 month, and the color tone and flavor of the sheep were examined. The color tone and flavor of the chestnut sheep were well preserved.

  The present invention is an oxygen-absorbing resin composition that is excellent in oxygen-absorbing performance at low and high humidity by using a specific polyamide resin and a transition metal, and can be applied to various containers and uses.

Claims (1)

  An oxygen-absorbing resin composition containing at least a transition metal catalyst and a polyamide resin, wherein the polyamide resin contains at least three components of metaxylylenediamine, adipic acid and sebacic acid, metaxylylenediamine: adipic acid: sebacin It is a polyamide resin having a terminal amino group concentration of 30 μeq / g or less formed by polycondensation at a molar ratio of acid = 0.985 to 0.997: 0.3 to 0.7: 0.7 to 0.3. An oxygen-absorbing resin composition.