JP2011025237A - Oxygen-absorbing resin composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resin composition excellent in oxygen absorption performance, resin strength and resin processability. <P>SOLUTION: In an oxygen-absorbing resin composition including a polyolefin resin, a transition metal catalyst and a polyamide resin, the polyamide resin is obtained by polycondensation of at least three components of meta-xylylenediamine, adipic acid and isophthalic acid in a molar ratio of meta-xylylenediamine:adipic acid:isophthalic acid=0.985-0.997:0.70-0.97:0.30-0.03 where a terminal amino group concentration of the polyamide resin is 30 μeq/g or lower, and also the total content of the transition metal catalyst and the polyamide resin is 15-60 wt.%. <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, MXD6, which is a polyamide obtained by polycondensation of metaxylylenediamine and adipic acid, has been disclosed as one that exhibits an oxidation reaction with a polyamide resin and a transition metal catalyst, but has a problem of low oxygen absorption capacity. Or, in a system in which transition metal is mixed with MXD6, 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 has been used.

Japanese Patent Laid-Open No. 9-234832 Japanese Patent Laid-Open No. 5-140555 JP 2001-252560 A JP 2003-34174 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 a specific polyamide and a transition metal with a polyolefin resin at a specific ratio, so that the oxygen absorption performance is excellent, the resin strength after storage is maintained, and the oxygen absorption is excellent in workability. It has been found that a resin composition is obtained.

  That is, the present invention provides an oxygen-absorbing resin composition containing a polyolefin resin, a transition metal catalyst, and a polyamide resin, wherein the polyamide resin contains at least three components of metaxylylenediamine, adipic acid, and isophthalic acid. Range amine: adipic acid: isophthalic acid = 0.985-0.997: 0.70-0.97: 0.30-0.03 molar concentration of terminal amino groups formed by polycondensation is 30 μeq / g or less The oxygen-absorbing resin composition is characterized in that the total content of the transition metal catalyst and the polyamide resin is 15 to 60% by weight.

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

  The oxygen-absorbing resin composition of the present invention comprises at least three components of metaxylylenediamine, adipic acid and isophthalic acid, metaxylylenediamine: adipic acid: isophthalic acid = 0.985 to 0.997: 0.70-0. Polyamide resin having a terminal amino group concentration of 30 μeq / g or less formed by polycondensation at a molar ratio of .97: 0.30 to 0.03 (hereinafter, the polyamide resin is particularly referred to as “polyamide resin A”) and a transition metal A resin composition containing a catalyst and a polyolefin resin. Hereinafter, the details of each resin and the transition metal catalyst 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, 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 a polycondensation reaction of metaxylylenediamine with adipic acid and isophthalic acid, and the molar ratio at that time is metaxylylenediamine: adipic acid: isophthalic acid = 0.985-0. .997: 0.70 to 0.97: 0.30 to 0.03 is preferable, and 0.988 to 0.995: 0.80 to 0.95: 0.20 to 0.05 is particularly preferable. The polycondensation reaction of metaxylylenediamine with adipic acid and isophthalic 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 isophthalic 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 isophthalic acid at the above molar ratio. When the terminal amino group concentration is 25 μeq / g or less, the oxygen absorption performance is improved, and when it is 20 μeq / g or less, the oxygen absorption performance is further improved. Thus, the oxygen absorption performance tends to improve as the terminal amino group concentration decreases, and it is preferable to reduce the concentration as much as possible. However, in consideration of economic rationality, the lower limit is 5 μeq / g or more. It is preferable to do. If the terminal amino group concentration is higher than 30 μeq / g, good oxygen absorption performance cannot be obtained.

In order to reduce the terminal amino group concentration of the polyamide resin to 30 μeq / g or less,
1) Method for carrying out polycondensation by adjusting the molar ratio of aromatic diamine and dicarboxylic acid 2) Method for reacting polyamide resin with carboxylic acid to seal the terminal amino group 3) Method for solid-phase polymerization of polyamide resin These methods are preferably carried out, and these methods can be carried out alone or in combination. In particular, 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 the method of carrying out polycondensation by adjusting the molar ratio of aromatic diamine and dicarboxylic acid, dicarboxylic acid is used excessively with respect to aromatic diamine. Specifically, aromatic diamine and dicarboxylic acid are used. The molar ratio (aromatic diamine / dicarboxylic acid) is preferably 0.985 to 0.997, particularly preferably 0.988 to 0.995. If the molar ratio is less than 0.985, it is difficult to increase the degree of polymerization of the polyamide resin.

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

  3) In the method of solid-phase polymerization of polyamide resin, the terminal amino group concentration is adjusted by further subjecting the polyamide resin obtained by melt polymerization to a solid-phase polymerization reaction. Solid phase polymerization proceeds by heating polyamide resin pellets under reduced pressure. The pressure during the solid phase polymerization is preferably 100 torr or less, and more preferably 30 torr or less. Further, the temperature at the time of solid phase polymerization needs to be 130 ° C. or 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 low crystallinity with a half-crystallization time of 150 seconds or more, or those having no melting point peak when measuring the melting point by DSC are preferable. When the half crystallization time of the polyamide resin A is 150 seconds or more, higher oxygen absorption performance can be obtained.

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

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

  The polyamide resin A obtained by polycondensation of metaxylylenediamine with adipic acid and isophthalic 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 18000 to 25000, particularly preferably 19000 to 24000.

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 polyolefins, 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), and has an oxygen permeability coefficient within this range. When a 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 organic acids 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 viscosity of the polyamide resin A is lowered and 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 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 containing the transition metal catalyst in the oxygen-absorbing resin composition is less than 15% by weight or exceeds 60% by weight, the oxygen-absorbing ability is lowered. On the other hand, if it exceeds 60% by weight, resin degradation due to oxidation of the polyamide resin A occurs, causing problems such as strength reduction.

  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 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.

  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.

  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. 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 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. If the thickness is too large, the oxygen absorption performance decreases, and if it is too small, a problem occurs in workability. 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 glutinous rice, cooked foods such as soup, stew, and curry, fruits, mutton, pudding, cakes, confectionery such as buns, tuna, and shellfish Seafood products such as seafood, 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.

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

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

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

(Synthesis conditions by melt polymerization of polyamide resin)
After heating and melting the dicarboxylic acid in a reaction can at 170 ° C., the aromatic diamine is gradually and continuously added so that the molar ratio of the dicarboxylic acid to the dicarboxylic acid is about 1: 1 while stirring the contents. And the temperature was raised to 240 ° C. After completion of dropping, the temperature was raised to 255 ° C. and the reaction was continued. After completion of the reaction, the inside of the reaction can was slightly pressurized with nitrogen, the strand was extruded from a die head having holes, and pelletized with a pelletizer.

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

Example 1
Polyamide resin was synthesized by performing melt polymerization and solid phase polymerization under the above-mentioned synthesis conditions using metaxylylenediamine: adipic acid: isophthalic acid in a molar ratio of 0.992: 0.93: 0.07. (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 195 ° C., and the polymerization time was 4 hours. Polyamide 1 has a Tg of 92 ° C., a melting point of 228 ° C., a half crystallization time of 160 seconds, a terminal amino group concentration of 12.1 μeq / g, a terminal carboxyl group concentration of 66.6 μeq / g, and a number average molecular weight of 26200 and 240 ° C. The MFR was 18 g / 10 minutes. Moreover, when the unstretched film was produced with the obtained polyamide 1 single-piece | unit and the oxygen permeability coefficient was calculated | required, it was 0.07cc * mm / (m < ² > * day * atm) (23 degreeC * 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: “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 was melt kneaded at 240 ° 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 was made into two films of 10 × 10 mm, the humidity inside the bag was adjusted to 100%, and each gas barrier bag made of aluminum foil laminated film was filled and sealed with 300 cc of air each two pieces. The sample was stored at 100 ° C. and 100% humidity, and the oxygen absorption amount for 7 days from the start of the storage was investigated. Further, the elongation percentage of the film one month after the start of storage was investigated. 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
Polyamide resin was synthesized by performing melt polymerization and solid phase polymerization under the above synthesis conditions using metaxylylenediamine: adipic acid: isophthalic acid in a molar ratio of 0.992: 0.80: 0.20. (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 180 ° C., and the polymerization time was 4 hours. Polyamide 2 has a Tg of 81 ° C., a melting point of 208 ° C., a semicrystallization time of 1200 seconds, a terminal amino group concentration of 16.5 μeq / g, a terminal carboxyl group concentration of 62.3 μeq / g, and a number average molecular weight of 24800, 240 ° C. The MFR was 14 g / 10 minutes. 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 0.07 cc * mm / (m < ² > * day * atm) (23 degreeC * 60% RH). .

  In the same manner as in Example 1, after adding cobalt stearate to polyamide 2, the weight ratio at the time of melt kneading was changed to cobalt stearate-containing polyamide 2: LLDPE = 18: 82, and Similarly, a film was produced, and the oxygen absorption amount, the elongation rate, and the appearance of the film were observed. These results are shown in Table 1.

(Comparative Example 1)
A polyamide resin was synthesized in the same manner as in Example 1 except that solid phase polymerization was not performed (hereinafter, the polyamide resin is referred to as polyamide 3). Polyamide 3 had a Tg of 90 ° C., a melting point of 229 ° C., a semicrystallization time of 148 seconds, a terminal amino group concentration of 43.5 μeq / g, a terminal carboxyl group concentration of 66.6 μeq / g, and a number average molecular weight of 1,7992. Moreover, at 240 degreeC, MFR of 240 degreeC was measured and it was 24.4 g / 10min. An unstretched film was prepared from the obtained polyamide 3 alone, and the oxygen transmission coefficient was determined. The oxygen transmission coefficient was 0.07 cc · mm / (m ² · day · atm) (23 ° C. · 60% RH). there were.

  Thereafter, in the same manner as in Example 1, addition of cobalt stearate to polyamide 3, melt kneading with LLDPE, and the like were performed to produce a film composed of a single layer oxygen-absorbing resin composition. Moreover, it carried out similarly to Example 1, and measured the oxygen absorption amount of this film, the measurement of elongation rate, and the external appearance observation. These results are shown in Table 1.

(Comparative 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 = 80: 20, and the oxygen absorption amount of the film was measured. Appearance was observed. These results are shown in Table 1.

(Comparative Example 3)
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.

  As is clear from Examples 1 to 4, 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. On the other hand, in Comparative Example 1 in which the amino group concentration of the polyamide resin exceeded 30 μeq / g, the oxygen absorption performance was poor, and in Comparative Examples 2 and 3 in which the polyamide resin was excessively blended in the resin composition, the film elasticity deteriorated. .

(Example 5)
A two-layer three-layer film 1 (thickness: 10 μm / 20 μm / 10 μm) in which the oxygen-absorbing resin composition obtained in Example 1 is a core layer and the skin layer is LLDPE, is 800 mm in width and 120 m / min. One side was prepared by corona discharge treatment. The appearance of the obtained film was good, and HAZE was 74%. Using the obtained two-type three-layer film 1, bleached kraft paper (basis weight: 340 g / m ² ) / urethane based on extrusion lamination with low density polyethylene (product name: “Mirason 18SP” manufactured by Mitsui Chemicals, Inc.) Adhesive for dry lamination (Product name: “TM251 / CAT-RT88”, 3) manufactured by Toyo Morton Co., Ltd./Alumina-deposited PET film (Product name: “GL-AEH”, 12 manufactured by Toppan Printing Co., Ltd.) / Urethane Anchor coating agent ("EL-557A / B" manufactured by Toyo Morton Co., Ltd., 0.5) / low density polyethylene (20) / LLDPE (10) / oxygen absorbing resin composition (20) / LLDPE (10) An oxygen-absorbing multilayer paper substrate 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 23 ° 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 PP Oxygen-absorbing resin composition was obtained in the same manner as in Example 1 except that was used. Next, a two-kind three-layer film 2 (thickness: 15 μm / 30 μm / 15 μm) was prepared in the same manner as in Example 5 except that the oxygen-absorbing resin composition was used as a core layer and the skin layer was replaced with PP instead of LLDPE. did. The obtained film had a HAZE of 64%. Urethane vapor-deposited PET (product name: Toppan Printing Co., Ltd. “GL-”) was used on the corona-treated surface side using urethane dry laminate adhesive (product name: “TM251 / CAT-RT88” manufactured by Toyo Morton Co., Ltd.). AEH ”, 12) / Adhesive (3) / Nylon (Product name:“ N1202 ”, 15 manufactured by Toyobo Co., Ltd.) / Adhesive (3) / PP (15) / Oxygen-absorbing resin composition (30) / An oxygen-absorbing multilayer film of PP (15) was obtained. Using this oxygen-absorbing multilayer film, a 10 × 20 cm three-side sealed bag was prepared, a circular steaming port having a diameter of 2 mm was provided in a part thereof, and the periphery of the steaming port was temporarily attached with a label seal. . The bag was filled with pasta sauce containing carrot and meat, sealed, retort cooked at 124 ° C for 30 minutes, heat sterilized, and stored at 23 ° C. The stew inside the bag was visible. One month later, the bag was heated as it was for about 4 minutes in a microwave oven, and after about 3 minutes, the bag was inflated, the temporarily attached label seal part was peeled off, and it was confirmed that steam was emitted from the steaming port. After cooking, when the flavor of the pasta sauce and the color of the carrot were investigated, the appearance of the carrot was well maintained.

(Comparative Example 4)
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 35:65 with LLDPE to obtain an iron powder-based oxygen-absorbing resin composition A. An iron powder-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 5. However, irregularities of iron powder occurred on the film surface, and no film was obtained. Therefore, an iron powder-based oxygen-absorbing resin composition A was extruded and laminated at a thickness of 20 μm as an oxygen-absorbing layer on LLDPE having a thickness of 40 μm, and a laminate film was obtained in which the oxygen-absorbing layer surface was subjected to corona discharge treatment. This laminate film was laminated with bleached kraft paper in the same manner as in Example 5, and bleached kraft paper (basis weight 340 g / m ² ) / urethane-based dry laminating adhesive (product name: “TM251 / CAT-” manufactured by Toyo Morton Co., Ltd.). RT88 ”, 3) / alumina-deposited PET film (product name:“ GL-AEH ”manufactured by Toppan Printing Co., Ltd., 12) / urethane anchor coating agent (“ EL-557A / B ”manufactured by Toyo Morton Co., Ltd.), 0 .5) / Low density polyethylene (product name: “Mirason 18SP”, manufactured by Mitsui Chemicals, Inc., 20) / iron powder-based oxygen-absorbing resin composition A (20) / LLDPE (40) An attempt was made to produce a bevel-top type paper container, 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 5)
An iron powder-based oxygen-absorbing resin composition B was obtained in the same manner as in Comparative Example 4 except that PP was used instead of LLDPE. Similarly, a laminated film of iron powder-based oxygen-absorbing resin composition B (20) / PP (40) was prepared in the same manner as in Comparative Example 4 except that PP was used instead of LLDPE, and then the oxygen-absorbing layer surface was corona. Discharge treatment was performed. In the same manner as in Example 6, alumina-deposited PET (product name: “GL-AEH”, 12 manufactured by Toppan Printing Co., Ltd.) / Adhesive (3) / nylon (product name: “N1202” manufactured by Toyobo Co., Ltd. 15) / adhesive (3) / iron powder-based oxygen-absorbing resin composition B (20) / PP (40) to obtain an oxygen-absorbing multilayer film. 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.

Claims (2)

  An oxygen-absorbing resin composition comprising a polyolefin resin, a transition metal catalyst, and a polyamide resin, wherein the polyamide resin comprises at least three components of metaxylylenediamine, adipic acid and isophthalic acid, metaxylylenediamine: adipic acid: 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 isophthalic acid = 0.985 to 0.997: 0.70 to 0.97: 0.30 to 0.03, The total content of the transition metal catalyst and the polyamide resin is 15 to 60% by weight.   The oxygen-absorbing resin composition according to claim 1, wherein the transition metal catalyst is cobalt stearate.