Sterilized oxygen-absorbing resin composition, sterilized oxygen-absorbing multilayer container and method for producing the same

Abstract

The present invention provides a sterilized oxygen-absorbing resin composition obtained by performing at least: a sterilizing step of irradiating with radiation an oxygen-absorbing resin composition containing a transition metal catalyst and a thermoplastic resin (a) having a tetralin ring as a constituent unit; and a step of heating the oxygen-absorbing resin composition at a temperature equal to or higher than the glass transition temperature of the thermoplastic resin (a) and equal to or lower than 200 C., after the sterilizing step.

Claims

1. A sterilized oxygen-absorbing resin composition obtained by performing at least: a sterilizing step of irradiating with radiation an oxygen-absorbing resin composition comprising a transition metal catalyst and a thermoplastic resin (a) having a tetralin ring as a constituent unit; and a step of heating the oxygen-absorbing resin composition at a temperature equal to or higher than a glass transition temperature of the thermoplastic resin (a) and equal to or lower than 200 C., after the sterilizing step.

2. The sterilized oxygen-absorbing resin composition according to claim 1, wherein a time of the heating is 1 to 120 minutes.

3. The sterilized oxygen-absorbing resin composition according to claim 1, wherein the thermoplastic resin (a) is a polyester compound comprising a constituent unit having at least one tetralin ring selected from the group consisting of the following general formulas (1) to (4): ##STR00007## wherein R independently represents a hydrogen atom or a monovalent substituent; the monovalent substituent is at least one selected from the group consisting of a halogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, a heterocyclic group, a cyano group, a hydroxy group, a carboxyl group, an ester group, an amide group, a nitro group, an alkoxy group, an aryloxy group, an acyl group, an amino group, a thiol group, an alkylthio group, an arylthio group, a heterocyclic thio group, and an imide group, these of which may further have a substituent; m represents an integer of 0 to 3; n represents an integer of 0 to 7; at least one hydrogen atom is bonded to a benzylic position of the tetralin ring; and X represents a divalent group comprising at least one group selected from the group consisting of an aromatic hydrocarbon group, a saturated or unsaturated alicyclic hydrocarbon group, a linear or branched, saturated or unsaturated aliphatic hydrocarbon group, and a heterocyclic group.

4. The sterilized oxygen-absorbing resin composition according to claim 1, wherein the transition metal catalyst comprises at least one transition metal selected from the group consisting of manganese, iron, cobalt, nickel, and copper.

5. The sterilized oxygen-absorbing resin composition according to claim 1, wherein the transition metal catalyst is contained in an amount of 0.001 to 10 parts by mass in terms of the amount of a transition metal based on 100 parts by mass of the thermoplastic resin (a).

6. The sterilized oxygen-absorbing resin composition according to claim 1, wherein the constituent unit represented by the general formula (1) is at least one selected from the group consisting of the following formulas (5) to (7). ##STR00008##

7. The sterilized oxygen-absorbing resin composition according to claim 1, wherein the radiation is at least one selected from the group consisting of gamma rays, X-rays, and electron beams.

8. A sterilized oxygen-absorbing multilayer container obtained by performing at least: a sterilizing step of irradiating with radiation an oxygen-absorbing multilayer container comprising an oxygen-absorbing multilayer body, wherein the oxygen-absorbing multilayer body comprises at least an oxygen absorbing layer (layer A) comprising an oxygen-absorbing resin composition comprising a transition metal catalyst and a thermoplastic resin (a) having a tetralin ring as a constituent unit and a layer (layer B) comprising a thermoplastic resin (b) formed on the oxygen absorbing layer (layer A); and a step of heating the oxygen-absorbing multilayer container at a temperature equal to or higher than a glass transition temperature of the thermoplastic resin (a) and equal to or lower than 200 C., after the sterilizing step.

9. The sterilized oxygen-absorbing multilayer container according to claim 8, wherein: the oxygen-absorbing multilayer container comprises an oxygen-absorbing multilayer body having three or more layers, the oxygen-absorbing multilayer body comprising at least the oxygen absorbing layer (layer A), a layer (layer B1) comprising a thermoplastic resin (b1) formed on one surface of the oxygen absorbing layer (layer A), and a layer (layer B2) comprising a thermoplastic resin (b2) formed on an other surface of the oxygen absorbing layer (layer A); and the temperature of the heating step is equal to or higher than the glass transition temperature of the thermoplastic resin (a) and equal to or lower than either a glass transition temperature of the thermoplastic resin (b1) or a glass transition temperature of the thermoplastic resin (b2).

10. A method for producing a sterilized oxygen-absorbing multilayer container, comprising: a sterilizing step of irradiating with radiation an oxygen-absorbing multilayer container comprising an oxygen-absorbing multilayer body, wherein the oxygen-absorbing multilayer body comprises at least an oxygen absorbing layer (layer A) comprising an oxygen-absorbing resin composition comprising a transition metal catalyst and a thermoplastic resin (a) having a tetralin ring as a constituent unit and a layer (layer B) comprising a thermoplastic resin (b) formed on the oxygen absorbing layer (layer A); and a step of heating the oxygen-absorbing multilayer container at a temperature equal to or higher than a glass transition temperature of the thermoplastic resin (a) and equal to or lower than 200 C., after the sterilizing step.

Description

EXAMPLES

(1) Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples, but the present invention is not limited to these. Note that NMR measurement was performed at room temperature using AVANCE 111-500 manufactured by BRUKER GmbH unless otherwise stated.

(2) [Synthesis Example of Monomer]

(3) An autoclave having an internal volume of 18 L was charged with 2.20 kg of naphthalene-2,6-dicarboxylic acid dimethyl ester, 11.0 kg of 2-propanol, and 350 g of a catalyst (containing water in an amount of 50% by weight) in which palladium is supported by activated carbon in an amount of 5%. Next, the air in the autoclave was replaced with nitrogen; the nitrogen was replaced with hydrogen; and then hydrogen was fed to the autoclave until the pressure therein reached 0.8 MPa. Then, a stirrer was started; the rotational speed thereof was adjusted to 500 rpm; the internal temperature was increased to 100 C. over 30 minutes; and hydrogen was further fed to bring the pressure to 1 MPa. Subsequently, the feeding of hydrogen was continued so as to maintain 1 MPa depending on the decrease of pressure due to the progress of reaction. Since the pressure decrease stopped after 7 hours, the autoclave was cooled, and unreacted residual hydrogen was released. Then, a reaction mixture was removed from the autoclave. The reaction mixture was filtered to remove the catalyst, and then 2-propanol was evaporated from the separated filtrate by an evaporator to obtain a crude product. To the resulting crude product was added 4.40 kg of 2-propanol, and the crude product was purified by recrystallization to obtain tetralin-2,6-dicarboxylic acid dimethyl ester at a yield (a yield based on naphthalene-2,6-dicarboxylic acid dimethyl ester) of 80%. Note that NMR analysis results were as described below. .sup.1H-NMR (400 MHz CDCl.sub.3) 7.76-7.96 (2H m), 7.15 (1H d), 3.89 (3H s), 3.70 (3H s), 2.70-3.09 (5H m), 1.80-1.95 (1H m).

(4) [Production Example of Polymer]

(5) An apparatus for producing a polyester resin equipped with a packed column type rectifier, a partial condenser, a total condenser, a cold trap, a stirrer, a heating device, and a nitrogen introducing tube was charged with 543 g of tetralin-2,6-dicarboxylic acid dimethyl ester obtained in the synthesis example of monomer, 217 g of ethylene glycol, and 0.171 g of tetrabutyl titanate and heated to 230 C. in a nitrogen atmosphere to perform transesterification reaction. The reaction conversion of the dicarboxylic acid component was increased to 85% or more, and then thereto was added 0.171 g of tetrabutyl titanate. The resulting mixture was gradually heated and decompressed and subjected to polycondensation at 245 C. and 133 Pa or less to obtain a polyester compound (1) having a structure represented by the following formula (5).

(6) ##STR00006##

(7) The weight average molecular weight and the number average molecular weight of the resulting polyester compound (1) were measured by gel permeation chromatography (GPC). As a result, the weight average molecular weight in terms of polystyrene was 8.510.sup.4, and the number average molecular weight was 3.010.sup.4. Note that the measurement conditions of GPC were as follows.

(8) Measurement device: HLC-8320GPC EcoSEC manufactured by Tosoh Corporation

(9) Columns used: TSKgel SuperH2000, TSKgel SuperHM-L, and TSKgel SuperHSO00 manufactured by Tosoh Corporation

(10) Solvent of mobile phase: Chloroform

(11) Temperature: 40 C.

(12) Flow rate: 0.6 mL/min

(13) As a result of measuring glass transition temperature and a melting point using a differential scanning calorimeter (DSC), the glass transition temperature was 67 C., and the melting point were not observed since the compound was amorphous. Note that the measurement conditions of DSC were as follows.

(14) Measurement device: DSC-60 manufactured by Shimadzu Corporation

(15) Measurement start temperature: 25 C.

(16) Heating rate: 10 C./min

(17) Arrival temperature: 220 C.

(18) Cooling rate: 5 C./min

Example 1-1

(19) An oxygen-absorbing resin composition was obtained by dry-blending cobalt (II) stearate with 100 parts by mass of the polyester compound (1) such that the amount of cobalt was adjusted to 0.02 part by mass. An oxygen-absorbing film having a width of 130 mm and a thickness of 245 to 255 m was prepared by film-forming the oxygen-absorbing resin composition under the conditions of an extrusion temperature of 220 C., a screw rotation speed of 60 rpm, a feed screw rotation speed of 16 rpm, and a haul-off speed of 1.3 m/min, using a twin-screw extruder having two screws each having a diameter of 20 mm. Then, a test piece (100 mm in length100 mm in width) of the resulting oxygen-absorbing film was irradiated (irradiation time: 5 hours) in air at room temperature with 50 kGy of gamma rays emitted from a Co.sup.60 radiation source.

(20) Next, the test piece irradiated with gamma rays was put in an automatic oven (model: DS400, manufactured by Yamato Scientific Co., Ltd.) and subjected to heat treatment for 15 minutes at 80 C. in air. Subsequently, the film was cooled to room temperature and then measured for yellowness (Yellow Index: YI). Further, the film after the gamma irradiation and heat treatment was stored for one week at 23 C. and 50% RH and then measured for YI. A color-difference and turbidity measuring device (model: COH-400, manufactured by Nippon Denshoku Industries Co., Ltd.) was used for the YI measurement. The results are shown in Table 1.

Examples 1-2 to 1-12

(21) Examples 1-2 to 1-12 were performed in the same manner as in Example 1-1 except that the gamma irradiation dose, heating temperature, and heating time were changed as shown in Table 1, and the oxygen-absorbing films were measured for YI. The results are shown in Table 1.

Example 1-13

(22) A test piece (100 mm in length x 100 mm in width) of the oxygen-absorbing film prepared in the same manner as in Example 1-1 was irradiated (irradiation time: 5 hours) in air at room temperature with 50 kGy of electron beams emitted from an electron beam generator using an electrostatic accelerator.

(23) Next, the test piece irradiated with electron beams was put in an automatic oven (model: DS400, manufactured by Yamato Scientific Co., Ltd.) and subjected to heat treatment for 15 minutes at 80 C. in air. Subsequently, the film was cooled to room temperature and then measured for YI. Further, the film after the electron beam irradiation and heat treatment was stored for one week at 23 C. and 50% RH and then measured for YI. The results are shown in Table 1.

Examples 1-14 to 1-18

(24) Examples 1-14 to 1-18 were performed in the same manner as in Example 1-13 except that the electron beam irradiation dose, heating temperature, and heating time were changed as shown in Table 1, and the oxygen-absorbing films were measured for YI. The results are shown in Table 1.

Comparative Example 1-1

(25) Comparative Example 1-1 was performed in the same manner as in Example 1-1 except that heat treatment was not performed, and the oxygen-absorbing films were measured for YI. The results are shown in Table 1.

Comparative Example 1-2

(26) Comparative Example 1-2 was performed in the same manner as in Comparative Example 1-1 except that the dose was set to 25 kGy, and the oxygen-absorbing films were measured for YI. The results are shown in Table 1.

Comparative Example 1-3

(27) Comparative Example 1-3 was performed in the same manner as in Example 1-13 except that heat treatment was not performed, and the oxygen-absorbing films were measured for YI. The results are shown in Table 1.

Comparative Example 1-4

(28) Comparative Example 1-4 was performed in the same manner as in Comparative Example 1-3 except that the dose was set to 25 kGy, and the oxygen-absorbing film were measured for YI. The results are shown in Table 1.

Comparative Example 1-5

(29) Comparative Example 1-5 was performed in the same manner as in Example 1-1 except that heating temperature was set to 50 C., and the oxygen-absorbing films were measured for YI. The results are shown in Table 1.

(30) TABLE-US-00001 TABLE 1 Type of radiation/ Heating dose (kGy) conditions YI of film (values inside the parentheses.sup.1) are YI) Gamma Electron Temperature/ Time/ Before radiation After radiation irradiation/ After heat One week after rays beams C. min irradiation before heat treatment treatment radiation irradiation Example 1-1 50 80 15 0.1 (0) 12.6 (+12.5) 3.7 (+3.6) 3.2 (+3.1) Example 1-2 50 80 5 0.2 (0) 12.2 (+12.4) 6.2 (+6.4) 5.4 (+5.6) Example 1-3 50 80 30 0.2 (0) 12.7 (+12.5) 3.4 (+3.2) 2.9 (+2.7) Example 1-4 50 100 15 0.0 (0) 12.5 (+12.5) 3.3 (+3.3) 2.8 (+2.8) Example 1-5 50 100 5 0.1 (0) 12.7 (+12.6) 5.8 (+5.7) 5.1 (+5.0) Example 1-6 50 100 30 0.0 (0) 12.5 (+12.5) 3.1 (+3.1) 2.6 (+2.6) Example 1-7 25 80 15 0.1 (0) 8.4 (+8.3) 2.8 (+2.7) 2.4 (+2.3) Example 1-8 25 80 5 0.1 (0) 8.1 (+8.2) 3.5 (+3.6) 3.0 (+3.1) Example 1-9 25 80 30 0.3 (0) 8.5 (+8.2) 2.8 (+2.5) 2.4 (+2.1) Example 1-10 25 100 15 0.2 (0) 8.0 (+8.2) 2.4 (+2.6) 1.9 (+2.1) Example 1-11 25 100 5 0.1 (0) 8.4 (+8.3) 3.3 (+3.2) 2.7 (+2.6) Example 1-12 25 100 30 0.2 (0) 8.6 (+8.4) 2.8 (+2.6) 2.4 (+2.2) Example 1-13 50 80 15 0.0 (0) 11.7 (+11.7) 3.3 (+3.3) 2.7 (+2.7) Example 1-14 50 80 5 0.1 (0) 11.8 (+11.7) 5.9 (+5.8) 5.1 (+5.0) Example 1-15 50 80 30 0.1 (0) 11.5 (+11.6) 2.9 (+3.0) 2.3 (+2.4) Example 1-16 25 80 15 0.2 (0) 7.8 (+7.6) 2.8 (+2.6) 2.4 (+2.2) Example 1-17 25 80 5 0.1 (0) 7.6 (+7.5) 3.4 (+3.3) 2.9 (+2.8) Example 1-18 25 80 30 0.0 (0) 7.5 (+7.5) 2.5 (+2.5) 2.0 (+2.0) Comparative Example 1-1 50 0.1 (0) 12.6 (+12.5) 10.7 (+10.6) Comparative Example 1-2 25 0.1 (0) 8.3 (+8.4) 7.1 (+7.2) Comparative Example 1-3 50 0.2 (0) 11.9 (+11.7) 10.3 (+10.1) Comparative Example 1-4 25 0.0 (0) 7.5 (+7.5) 6.7 (+6.7) Comparative Example 1-5 50 50 15 0.1 (0) 12.4 (+12.3) 9.8 (+9.7) 9.1 (+9.0) .sup.1)Based on values before radiation irradiation

(31) As described above, it was verified that, by performing heat treatment after radiation irradiation, the YI of a film of each Example more greatly decreased than the YI of a film of each Comparative Example, and the low YI was maintained thereafter. That is, it was at least verified that the implementation of heat treatment is very effective for fading the coloration due to radiation irradiation in a short time.

(32) [Production Example of Multilayer Container (Vial)]

(33) An injection-molded product having a three-layer constitution of B/A/B was obtained under the following conditions by injecting a material forming the layer B from an injection cylinder, then injecting a material forming the layer A from a separate injection cylinder simultaneously with the resin forming the layer B, and then injecting a required amount of the resin forming the layer A to fill a cavity in an injection mold. Then, the injection-molded product was cooled to a predetermined temperature, transferred to a blow mold, and then subjected to blow molding to produce a vial (bottle part). The total mass of the vial was set to 24 g, and the proportion (content) of the layer A was set to 30% by mass of the total mass of the vial. A cycloolefin polymer (COP, manufactured by Zeon Corporation, trade name ZEONEX 690R, glass transition temperature (Tg) 136 C., total light transmittance (ASTM D1003, 3 mm in thickness) 92%) was used as a resin forming the layer B.

(34) (Shape of Vial)

(35) The total length was set to 89 mm; the outer diameter was set to 40 mm ; and the thickness was set to 1.8 mm. Note that an integrated injection blow molding machine (manufactured by UNILOY, model: IBS 85, providing four vials) was used for producing the vial.

(36) (Molding Conditions for Vial)

(37) Injection cylinder temperature for layer A: 260 C.

(38) Injection cylinder temperature for layer B: 280 C.

(39) Temperature of resin flow channel in injection mold: 280 C.

(40) Blow temperature: 150 C.

(41) Temperature of cooling water for blow mold: 15 C.

(42) [Evaluation of Vial]

(43) The vials obtained in Examples and Comparative Examples were measured and evaluated for the oxygen transmission rate according to the following method.

(44) Oxygen Transmission Rate (OTR) of Vial

(45) A molded product was stored in an atmosphere of a temperature of 23 C., a relative humidity outside the molded product of 50%, and a relative humidity inside the molded product of 100%, and measured for the oxygen transmission rate on the 30th day from the start of the experiment. An oxygen transmission rate measurement apparatus (manufactured by MOCON, Inc., trade name OX-TRAN 2-21 ML) was used for the measurement. It means that the lower the measured value becomes, the better the oxygen barrier property becomes. Note that the minimum limit of detection of the measurement is an oxygen transmission rate of 510.sup.5 mL/(0.21 atm.Math.day.Math.package).

Example 2-1

(46) An oxygen-absorbing resin composition was obtained by dry-blending cobalt (II) stearate with 100 parts by mass of the polyester compound (1) such that the amount of cobalt was adjusted to 0.02 part by mass, feeding the blended material to a twin-screw extruder having two screws each having a diameter of 37 mm at a feeding rate of 30 kg/h, melt-kneading the material at a cylinder temperature of 220 C., extruding a strand from an extruder head, cooling the strand, and then pelletizing the cooled strand. A vial was produced using the oxygen-absorbing resin composition as a resin forming the layer A. Then, the resulting oxygen-absorbing multilayered vial was irradiated (irradiation time: about 5 hours) in air at room temperature with 50 kGy of gamma rays emitted from a Co.sup.60 radiation source. Next, the vial irradiated with gamma rays was put in an automatic oven (model: DS400, manufactured by Yamato Scientific Co., Ltd.) and subjected to heat treatment for 15 minutes at 80 C. in air. Subsequently, the vial was cooled to room temperature and then measured for YI and the oxygen transmission rate in the same manner as in Example 1-1. Further, the multilayered vial after the gamma irradiation and heat treatment was stored for one week at 23 C. and 50% RH and then measured for YI. The results are shown in Table 2.

Examples 2-2 to 2-12

(47) Examples 2-2 to 2-12 were performed in the same manner as in Example 2-1 except that the gamma irradiation dose, heating temperature, and heating time were changed as shown in Table 2, and the oxygen-absorbing multilayered vials were measured for YI and the oxygen transmission rate. The results are shown in Table 2.

Example 2-13

(48) The oxygen-absorbing multilayered vial prepared in the same manner as in Example 2-1 was irradiated (irradiation time: 5 hours) in air at room temperature with 50 kGy of electron beams emitted from an electron beam generator using an electrostatic accelerator. Next, the vial irradiated with electron beams was put in an automatic oven (model: DS400, manufactured by Yamato Scientific Co., Ltd.) and subjected to heat treatment for 15 minutes at 80 C. in air. Subsequently, the vial was cooled to room temperature and then measured for YI and the oxygen transmission rate. Further, the multilayered vial after the electron beam irradiation and heat treatment was stored for one week at 23 C. and 50% RH and then measured for YI. The results are shown in Table 2.

Examples 2-14 to 2-18

(49) Examples 2-14 to 2-18 were performed in the same manner as in Example 2-13 except that the electron beam irradiation dose, heating temperature, and heating time were changed as shown in Table 2, and the oxygen-absorbing multilayered vials were measured for YI and the oxygen transmission rate. The results are shown in Table 2.

Comparative Example 2-1

(50) Comparative Example 2-1 was performed in the same manner as in Example 2-1 except that heat treatment was not performed, and the vials were measured for YI and the oxygen transmission rate. The results are shown in Table 2.

Comparative Example 2-2

(51) Comparative Example 2-2 was performed in the same manner as in Comparative Example 2-1 except that the dose was set to 25 kGy, and the oxygen-absorbing multilayered vials were measured for YI and the oxygen transmission rate. The results are shown in Table 2.

Comparative Example 2-3

(52) Comparative Example 2-3 was performed in the same manner as in Example 2-13 except that heat treatment was not performed, and the vials were measured for YI and the oxygen transmission rate. The results are shown in Table 2.

Comparative Example 2-4

(53) Comparative Example 2-4 was performed in the same manner as in Comparative Example 2-3 except that the dose was set to 25 kGy, and the oxygen-absorbing multilayered vials were measured for YI and the oxygen transmission rate. The results are shown in Table 2.

Comparative Example 2-5

(54) Comparative Example 2-5 was performed in the same manner as in Example 2-1 except that heating temperature was set to 50 C., and the oxygen-absorbing multilayered vials were measured for YI and the oxygen transmission rate. The results are shown in Table 2.

(55) TABLE-US-00002 TABLE 2 Type of radiation/ Heating YI of multilayered vial (values inside the parentheses.sup.1) are YI) dose (kGy) conditions After radiation One week after Gamma Electron Temperature/ Time/ Before radiation irradiation/before After heat radiation Oxygen transmission rays beams C. min irradiation heat treatment treatment irradiation rate Example 2-1 50 80 15 0.3 (0) 31.6 (+31.9) 14.9 (+15.2) 12.3 (+12.6) Under detection limit Example 2-2 50 80 5 0.5 (0) 31.7 (+32.2) 25.3 (+25.8) 22.3 (+22.8) Under detection limit Example 2-3 50 80 30 0.6 (0) 31.4 (+32.0) 9.3 (+9.9) 6.5 (+7.1) Under detection limit Example 2-4 50 100 15 0.4 (0) 31.7 (+32.1) 9.3 (+9.7) 6.5 (+6.9) Under detection limit Example 2-5 50 100 5 0.5 (0) 31.4 (+31.9) 21.6 (+22.1) 19.0 (+19.5) Under detection limit Example 2-6 50 100 30 0.5 (0) 31.7 (+32.2) 8.9 (+9.4) 6.3 (+6.8) Under detection limit Example 2-7 25 80 15 0.3 (0) 19.9 (+20.2) 9.9 (+10.2) 7.8 (+8.1) Under detection limit Example 2-8 25 80 5 0.2 (0) 19.7 (+19.9) 13.6 (+13.8) 10.7 (+10.9) Under detection limit Example 2-9 25 80 30 0.4 (0) 20.1 (+20.5) 7.2 (+7.6) 5.8 (+6.2) Under detection limit Example 2-10 25 100 15 0.6 (0) 19.7 (+20.3) 7.3 (+7.9) 5.9 (+6.5) Under detection limit Example 2-11 25 100 5 0.5 (0) 19.6 (+20.1) 10.5 (+11.0) 8.3 (+8.8) Under detection limit Example 2-12 25 100 30 0.4 (0) 19.7 (+20.1) 7.0 (+7.4) 5.7 (+6.1) Under detection limit Example 2-13 50 80 15 0.3 (0) 30.3 (+30.6) 12.7 (+13.0) 9.8 (+10.1) Under detection limit Example 2-14 50 80 5 0.3 (0) 30.5 (+30.8) 23.1 (+23.4) 20.4 (+20.7) Under detection limit Example 2-15 50 80 30 0.2 (0) 30.3 (+30.5) 8.4 (+8.6) 6.1 (+6.3) Under detection limit Example 2-16 25 80 15 0.4 (0) 17.7 (+18.1) 8.0 (+8.4) 6.2 (+6.6) Under detection limit Example 2-17 25 80 5 0.4 (0) 18.0 (+18.4) 11.8 (+12.2) 9.2 (+9.6) Under detection limit Example 2-18 25 80 30 0.3 (0) 17.7 (+18.0) 7.0 (+7.3) 5.6 (+5.9) Under detection limit Comparative 50 0.6 (0) 31.6 (+32.2) 27.2 (+27.8) Under detection limit Example 2-1 Comparative 25 0.5 (0) 19.9 (+20.4) 17.2 (+17.7) Under detection limit Example 2-2 Comparative 50 0.3 (0) 30.4 (+30.7) 25.1 (+25.4) Under detection limit Example 2-3 Comparative 25 0.2 (0) 18.1 (+18.3) 15.9 (+16.1) Under detection limit Example 2-4 Comparative 50 50 15 0.4 (0) 31.5 (+31.9) 28.8 (+29.2) 26.7 (+27.1) Under detection limit Example 2-5 .sup.1)Based on values before radiation irradiation

(56) From the results of Examples described above, it was verified that, by performing heat treatment after radiation irradiation, the YI of multilayered vials more greatly decreased compared with those of Comparative Examples, and the low YI was maintained thereafter. Further, the oxygen-absorbing performance was maintained even after heat treatment. Thus, it was verified that the implementation of heat treatment had been very effective for fading the coloration due to radiation irradiation in a short time. Further, it was also verified that the vial of each Example showed no plastic deformation by heating and had good moldability.

(57) The present application is based on Japanese Patent Application filed with the Japan Patent Office on Feb. 6, 2014 (Japanese Patent Application No. 2014-021347), the contents of which are incorporated herein by reference.

INDUSTRIAL APPLICABILITY

(58) The sterilized oxygen-absorbing resin composition, the sterilized oxygen-absorbing multilayer container, and the method for producing the same according to the present invention can be utilized as a material and the like of a container for storing various objects including foods, beverages, drugs, and cosmetics.