JP2011127094A - Oxygen-absorbing resin composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an oxygen-absorbing resin composition excellent in resin processability, widely applicable to usages and excellent in oxygen absorption performance. <P>SOLUTION: The oxygen-absorbing resin composition comprises a polyolefin resin, a transition metal catalyst and a polyamide resin, wherein the polyamide resin is prepared by condensation polymerization of adipic acid with a diamine component comprising 80-20 mol% metaxylylene diamine and 20-80 mol% para-xylylene diamine to have ≤30 μeq/g terminal amino group concentration, and the sum total amount of the transition metal catalyst and the polyamide resin is 15-60 wt.% based on the whole amount of the oxygen-absorbing resin composition. <P>COPYRIGHT: (C)2011,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.

  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).

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

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

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

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

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

  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.

  The present inventors blended specific polyamides, transition metals and polyolefin resins in specific ratios, so that oxygen absorption performance is excellent, resin strength after storage is maintained, and oxygen absorption is excellent in processability. It has been found that a resin composition is obtained.

  That is, the present invention is an oxygen-absorbing resin composition containing a polyolefin resin, a transition metal catalyst, and a polyamide resin, wherein the polyamide resin contains 80 to 20 mol% of metaxylylenediamine and 20 to 80 mol% of paraxylylenediamine. It is a polyamide resin having a terminal amino group concentration of 30 μeq / g or less obtained by polycondensation of the diamine component and adipic acid, and the total content of the transition metal catalyst and the polyamide resin is the oxygen-absorbing resin composition. An oxygen-absorbing resin composition characterized by being 15 to 60% by weight based on the total amount.

  According to the present invention, it is possible to provide an oxygen-absorbing resin composition that has high oxygen-absorbing performance and hardly undergoes strength deterioration due to oxidation of a polyamide resin.

  The oxygen-absorbing resin composition of the present invention has a terminal amino group concentration of 30 μeq obtained by polycondensation of a diamine component containing 80 to 20 mol% of metaxylylenediamine and 20 to 80 mol% of paraxylylenediamine and adipic acid. / G or less of a polyamide resin (hereinafter, the polyamide resin is particularly referred to as “polyamide resin A”), a transition metal catalyst, and a polyolefin resin. Details of each component of the resin composition will be described below.

  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, but surprisingly, the polyamide resin A and the transition metal are mixed with the polyolefin resin. The present inventors have found that a high oxygen absorption ability is exhibited when blended at a constant ratio.

  The polyamide resin A in the present invention is obtained by polycondensation of a diamine component containing at least 80 to 20 mol% of metaxylylenediamine and 20 to 80 mol% of paraxylylenediamine and adipic acid. The polycondensation of the diamine component and adipic acid can proceed by melt polymerization in which the diamine component and adipic acid are melted, or solid phase polymerization in which polyamide resin pellets are heated under reduced pressure.

  Examples of the diamine component for producing the polyamide resin A include a mixture of paraxylylenediamine and metaxylylenediamine. Each content (mol%) at the time of mixing is preferably paraxylylenediamine: metaxylylenediamine = 20 to 60:80 to 40, particularly preferably 25 to 50:75 to 50. Furthermore, various aliphatic diamines and other aromatic diamines may be incorporated as copolymerization components as long as the performance is not affected.

  The polyamide resin A in the present invention has a terminal amino group concentration obtained by polycondensation of a diamine component containing at least 80 to 20 mol% of metaxylylenediamine and 20 to 80 mol% of paraxylylenediamine and adipic acid to 30 μeq / Although the polyamide resin is not more than g, the terminal amino group concentration is preferably 25 μeq / g or less because oxygen absorption performance is improved, and it is more preferably 20 μeq / g or less because oxygen absorption performance is further improved. Thus, the oxygen absorption performance tends to improve as the terminal amino group concentration decreases, and it is preferable to reduce the concentration as much as possible. However, in consideration of economic rationality, the lower limit is 5 μeq / g or more. It is preferable to do. If the terminal amino group concentration is higher than 30 μeq / g, good oxygen absorption performance cannot be obtained.

In order to reduce the terminal amino group concentration of the polyamide resin to 30 μeq / g or less,
1) A method in which polycondensation is carried out by adjusting the molar ratio of a diamine component containing at least metaxylylenediamine and paraxylylenediamine and adipic acid. 2) A terminal amino group is blocked by reacting a polyamide resin with a carboxylic acid. Method 3) It is preferable to carry out a method such as a method of solid-phase polymerization of a polyamide resin, and these methods can be carried out alone or in combination. In particular, the combination of the methods 1), 3), 2) and 3) is preferable because a polyamide resin having better oxygen absorption performance and moldability at the time of producing a multilayer body can be obtained. Hereinafter, these methods will be described.

  1) In a method in which polycondensation is carried out by adjusting the molar ratio of a diamine component containing at least metaxylylenediamine and paraxylylenediamine to adipic acid, adipic acid is used in excess of the diamine component. Specifically, the molar ratio of the diamine component and adipic acid (the diamine component / adipic acid) is preferably 0.985 to 0.997, particularly preferably 0.988 to 0.995. . If the molar ratio is less than 0.985, it is difficult to increase the degree of polymerization of the polyamide resin.

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

  3) In the method of solid-phase polymerization of polyamide resin, the terminal amino group concentration is adjusted by further subjecting the polyamide resin obtained by melt polymerization to a solid-phase polymerization reaction. Solid phase polymerization proceeds by heating polyamide resin pellets under reduced pressure. The pressure during the solid phase polymerization is preferably 100 torr or less, and more preferably 30 torr or less. Further, the temperature at the time of solid phase polymerization needs to be 130 ° C. or 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.

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

  A polyamide resin A obtained by polycondensation of a diamine component containing at least 80 to 20 mol% of metaxylylenediamine and 20 to 80 mol% of paraxylylenediamine and adipic acid is subjected to solid-phase polymerization after melt polymerization. It is preferable to synthesize by a method that goes through a step. The number average molecular weight of the polyamide resin A is preferably 18000 to 27000, particularly preferably 20000 to 26000.

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

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

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

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

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

  The total content of the transition metal catalyst and the polyamide resin A in the oxygen-absorbing resin composition is 15 to 60% by weight, preferably 17 to 60% by weight, more preferably 20 to 60% by weight, and 25 to 50% by weight. Is particularly preferred. When the content of the polyamide resin A including the transition metal catalyst in the oxygen-absorbing resin layer is less than 15% by weight or exceeds 60% by weight, the oxygen-absorbing ability is lowered. On the other hand, if it exceeds 60% by weight, resin degradation due to oxidation of the polyamide resin A occurs, causing problems such as strength reduction.

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

  When the master batch of the present invention and the polyamide resin A are melt-kneaded, the content of the polyamide resin A and the transition metal concentration can be adjusted by simultaneously adding the polyolefin resin.

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

  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 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, the oxygen-absorbing resin composition of the present invention is in the form of a film or a sheet, and includes at least three of 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 as an oxygen-absorbing multilayer body formed by laminating layers.

  In this case, the sealant layer containing the polyolefin resin is preferably the same as the polyolefin resin used in the oxygen-absorbing resin composition in consideration of compatibility. 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 smaller because the sealant layer becomes an isolation layer from the layer containing the oxygen-absorbing resin composition, but is particularly preferably 2 to 50 μm, and particularly preferably 5 to 30 μm. In this case, compared with the case where the thickness is out of the above range, 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 rice processing such as polished rice, cooked rice, red rice, and glutinous rice, cooked foods such as soup, stew, and curry, fruit, mutton, pudding, cake, confectionery such as buns, tuna, and fish shellfish Examples include fishery products, processed milk products such as cheese and butter, processed meat products such as meat, salami, sausage and ham, vegetables such as carrots, potatoes, asparagus and shiitake mushrooms, and eggs.

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

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

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

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

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

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

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

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

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

(Synthesis conditions by melt polymerization of polyamide resin)
After adipic acid is heated and melted at 170 ° C. in a reaction can, the diamine component is gradually added dropwise continuously so that the molar ratio with adipic 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
Metaxylylenediamine and paraxylylenediamine are mixed at a ratio of 7: 3, and these diamines and adipic acid are used in a molar ratio of 0.993: 1. (Hereinafter, the polyamide resin is referred to as polyamide 1). However, the dropping time was 2 hours, the polymerization temperature after completion of dropping of metaxylylenediamine in melt polymerization was 277 ° C., and the reaction time was 30 minutes. This polyamide 1 had a Tg of 87 ° C., a melting point of 259 ° C., a half crystallization time of 18 seconds, a terminal amino group concentration of 15.8 μeq / g, a terminal carboxyl group concentration of 66.8 μeq / g, and a number average molecular weight of 21,500. Moreover, MFR in 280 degreeC was 12.8 g / 10min. An unstretched film was prepared from the obtained polyamide 1 alone, and the oxygen permeability coefficient was determined. The oxygen permeability coefficient was 0.13 cc · mm / (m ² · day · atm) (23 ° C. · 60% RH). there were.

  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: “Knel KF380” manufactured by Nippon Polyethylene Co., Ltd.) is used as a polyolefin resin in a mixture of the obtained polyamide and cobalt stearate (hereinafter referred to as cobalt stearate-containing polyamide 1). MFR 4.0 g / 10 min (measured according to JIS K7210), 240 ° C. MFR 8.7 g / 10 min, 250 ° C. MFR 10.0 g / 10 min, hereinafter referred to as LLDPE) Polyamide 1: LLDPE = 35: 65 In a weight ratio, the mixture was melt-kneaded at 280 ° C. to obtain an oxygen-absorbing resin composition. Subsequently, when the film which consists of a 50-micrometer-thick oxygen absorption resin composition was obtained using this oxygen absorption resin composition and the external appearance of the film was observed, the external appearance of the film was favorable. The film is a 10 cm × 10 cm film, and the film is filled and sealed with two 300 cc air each in a gas barrier bag made of an aluminum foil laminated film with the humidity in the bag being 100%, and stored at 23 ° C., The total amount of oxygen absorbed in 7 days after sealing was measured. Further, the elongation percentage of the film after storage at 40 ° C. and 100% humidity for 1 month was measured. These results are shown in Table 1.

(Example 2)
A film was produced in the same manner as in Example 1 except that the weight ratio at the time of melt kneading was changed to cobalt stearate-containing polyamide 1: LLDPE = 55: 45, and the oxygen absorption amount of the film was measured. Appearance was observed. These results are shown in Table 1.

(Example 3)
A film was produced in the same manner as in Example 1 except that the weight ratio at the time of melt-kneading was changed to cobalt stearate-containing polyamide 1: LLDPE = 25: 75, and the oxygen absorption amount of the film was measured. Appearance was observed. These results are shown in Table 1.

Example 4
A film was produced in the same manner as in Example 1 except that the weight ratio at the time of melt-kneading was changed to cobalt stearate-containing polyamide 1: LLDPE = 17: 83, and the oxygen absorption amount of the film was measured. Appearance was observed. These results are shown in Table 1.

(Example 5)
Cobalt stearate was added to LLDPE by side feed to the melted LLDPE with a twin screw extruder so that the cobalt concentration was 600 ppm. Furthermore, polyamide 1 was melt-kneaded at 280 ° C. in a weight ratio of polyamide 1: cobalt stearate-containing LLDPE1 = 35: 65 to the obtained mixture of LLDPE and cobalt stearate to obtain oxygen-absorbing resin pellets.

  Thereafter, a film was produced in the same manner as in Example 1, and the oxygen absorption amount, elongation rate, and appearance of the film were observed. These results are shown in Table 1.

(Comparative Example 1)
A film was produced in the same manner as in Example 1 except that the weight ratio at the time of melt kneading was changed to cobalt stearate-containing polyamide 1: LLDPE = 80: 20, and the film was measured for oxygen absorption, elongation measurement, and appearance. Was observed. These results are shown in Table 1.

(Comparative Example 2)
A film was produced in the same manner as in Example 1 except that it was not melt-kneaded with LLDPE and was made of only cobalt stearate-containing polyamide 1. The film was measured for oxygen absorption, measured for elongation, and observed for appearance. Went. These results are shown in Table 1.

(Comparative Example 3)
A film was produced in the same manner as in Example 1 except that the weight ratio at the time of melt kneading was changed to cobalt stearate-containing polyamide 1: LLDPE = 10: 90, measurement of oxygen absorption amount of the film, measurement of elongation rate, appearance Was observed. These results are shown in Table 1.

(Comparative Example 4)
Metaxylylenediamine and paraxylylenediamine were mixed at a ratio of 7: 3, and these diamines and adipic acid were used in a molar ratio of 0.999: 1 to synthesize a polyamide resin without performing solid phase polymerization ( Hereinafter, the polyamide resin is referred to as polyamide 2.) Polyamide 2 had a Tg of 78 ° C., a melting point of 237 ° C., a semicrystallization time of 27 seconds, a terminal amino group concentration of 39.1 μeq / g, a terminal carboxyl group concentration of 70.2 μeq / g, and a number average molecular weight of 17,800. The MFR at 250 ° C. was 51 g / 10 minutes.
Thereafter, a film was produced in the same manner as in Example 1 except that the temperature at the time of melt kneading was 250 ° C., and the oxygen absorption amount, the elongation rate, and the appearance of the film were observed. These results are shown in Table 1.

  As is clear from Examples 1 to 5, the oxygen-absorbing resin composition of the present invention was a resin composition that exhibited good oxygen-absorbing performance and retained film elasticity after oxygen absorption.

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

  On the other hand, as compared with Example 1, in Comparative Example 4 in which solid phase polymerization was not performed, the terminal amino group concentration exceeded 30 μeq / g, and good oxygen absorption performance could not be obtained. In Comparative Example 4, the appearance of the film was also deteriorated.

(Example 6)
A four-kind, six-layer multilayer 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 is used. From each extruder, a first extruder; a polypropylene 1, a second extruder ; Oxygen absorbing resin prepared in Example 1, third extruder; MXD6 (product name; manufactured by Mitsubishi Gas Chemical Co., Ltd. S7007, hereinafter referred to as MXD6), and fourth extruder; polypropylene adhesive resin (product name: Mitsubishi) Chemical Modic P604V) was extruded to obtain an oxygen-absorbing multilayer sheet. The multilayer sheet is composed of polypropylene 1 (100) / oxygen absorbing resin layer (100) / adhesive layer (15) / MXD6 layer (30) / adhesive layer (15) / polypropylene 1 (250) from the inner layer. The numbers in parentheses mean the thickness of each layer (unit: μm). In the following examples, the same notation is used unless otherwise specified. The multilayer sheet obtained by coextrusion was a multilayer sheet having a good appearance with no thickness unevenness.

Next, the obtained multilayer sheet was thermoformed into a cup-shaped container (inner volume 70 cc, surface area 120 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. 60 g of tuna is put in this container, and PET film (product name: Toyobo E5102), aluminum foil, unstretched polypropylene film (product name: Okamoto Aroma UT21) is dried with urethane adhesive (product name: Toyo Morton TM251). Laminated gas barrier film (PET film (12) / adhesive (3) / aluminum foil (7) / adhesive (3) / unstretched polypropylene film (60)) as a top film, sealed and filled The body container was retorted at 125 ° C. for 25 minutes, stored under conditions of 25 ° C. and 60% RH, opened after measuring the oxygen concentration in the container at the third month, and the flavor and color tone of tuna were confirmed. The oxygen concentration in the container was maintained at 0.1% or less, and the color tone and flavor of the tuna were good.

  The present invention blends a specific polyamide resin, transition metal and polyolefin resin at a specific ratio, so that it has excellent oxygen absorption performance at both low humidity and high humidity, maintains the resin strength after storage, The oxygen-absorbing resin composition was excellent in processability and applicable to various containers and uses.

Claims (3)

  An oxygen-absorbing resin composition containing a polyolefin resin, a transition metal catalyst and a polyamide resin, wherein the polyamide resin contains 80 to 20 mol% of metaxylylenediamine and 20 to 80 mol% of paraxylylenediamine; It is a polyamide resin having a terminal amino group concentration of 30 μeq / g or less obtained by polycondensation with adipic acid, and the total content of the transition metal catalyst and the polyamide resin is 15 to 15% based on the total amount of the oxygen-absorbing resin composition. An oxygen-absorbing resin composition characterized by being 60% by weight.   The oxygen-absorbing resin composition according to claim 1, wherein the transition metal catalyst is cobalt stearate.   3. The oxygen-absorbing resin composition according to claim 1, wherein a molar ratio (the diamine component / adipic acid) in obtaining the polyamide resin is 0.985 to 0.997.