Multilayer Structure, and Packaging Material for Retort Using Same

Abstract

The present invention relates to a multilayer structure at least an outer layer and an inner layer which contain a polypropylene resin as a main component, a barrier resin layer containing an ethylene-vinyl alcohol copolymer as a main component, and a metal deposited layer containing aluminum as a main component; a packaging material for a retort therewith; a method for recovering the multilayer structure; and a recovered composition comprising a recovered material of the multilayer structure. There is provided a multilayer structure exhibiting excellent recyclability and excellent appearance, gas barrier ability and shading performance both before and after retorting treatment, and a packaging material for a retort therewith.

Claims

1. A four or more layered multilayer structure comprising at least an outer layer (A) containing a polypropylene resin (a) as a main component, an inner layer (B) containing a polypropylene resin (b) as a main component, a barrier resin layer (C) containing an ethylene-vinyl alcohol copolymer (c) as a main component, and a metal deposited layer (D) containing aluminum as a main component, wherein the barrier resin layer (C) and the metal deposited layer (D) are positioned between the outer layer (A) and the inner layer (B); the total thickness is 200 μm or less; the polypropylene resin (a) and the polypropylene resin (b) have a melting point of 140° C. or more and less than 170° C., respectively; the ethylene-vinyl alcohol copolymer (c) has an ethylene unit content of 15 to 60 mol % and a saponification degree of 85 mol % or more; and the multilayer structure contains neither a layer containing a resin having a melting point of less than 140° C. as a main component, a layer containing a resin having a melting point of 240° C. or more, nor a metal layer having a thickness of 1 μm or more.

2. The multilayer structure as claimed in claim 1, wherein the barrier resin layer (C) and the metal deposited layer (D) are adjacent to each other.

3. The multilayer structure as claimed in claim 1, wherein the barrier resin layer (C) is a monolayer film having a thickness of 8 to 40 μm.

4. The multilayer structure as claimed in claim 3, wherein the monolayer film is biaxially stretched.

5. The multilayer structure as claimed in claim 1, wherein the barrier resin layer (C) is one layer of a coextruded film consisting of two or more layers including the barrier resin layer (C); a thickness of the coextruded film is 8 to 120 μm; and a thickness of the barrier resin layer (C) is 1 to 20 μm.

6. The multilayer structure as claimed in claim 5, wherein the coextruded film is biaxially stretched.

7. The multilayer structure as claimed in claim 5, wherein a layer of the coextruded film except for the barrier resin layer (C) is composed of a layer containing a polypropylene resin as a main component.

8. The multilayer structure as claimed in claim 1, wherein at least one barrier resin layer (C) is positioned in the outer layer (A) side with respect to at least one metal deposited layer (D).

9. The multilayer structure as claimed in claim 1, wherein a ratio of the total thickness of the layers containing a polypropylene resin as a main component to the total thickness of the multilayer structure is 0.75 or more.

10. The multilayer structure as claimed in claim 1, wherein the ethylene-vinyl alcohol copolymer (c) contains 20 to 200 ppm of at least one polyvalent metal ion (e) selected from the group consisting of magnesium ion, calcium ion and zinc ion.

11. The multilayer structure as claimed in claim 1, wherein the ethylene-vinyl alcohol copolymer (c) contains 40 to 400 ppm of a polycarboxylic acid (f) having at least one pKa of 3.5 to 5.5.

12. The multilayer structure as claimed in claim 1, wherein the ethylene-vinyl alcohol copolymer (c) contains 1000 to 10000 ppm of a hindered phenolic compound (g) having an ester bond or an amide bond.

13. The multilayer structure as claimed in claim 1, wherein the barrier resin layer (C) further contains a polyamide resin (h) and a mass ratio (c/h) of the ethylene-vinyl alcohol copolymer (c) to the polyamide resin (h) is 78/22 to 98/2.

14. A packaging material for a retort comprising the multilayer structure as claimed in claim 1.

15. The packaging material for a retort as claimed in claim 14, wherein an oxygen transmission rate (at 20° C. and 65% RH) both before and after retorting treatment at 120° C. for 30 min is less than 2 cc/(m.sup.2.Math.day.Math.atm).

16. The packaging material for a retort as claimed in claim 14, wherein a light transmittance at a wavelength of 600 nm both before and after retorting treatment at 120° C. for 30 min is 10% or less.

17. A recovered composition comprising a recovered material of the multilayer structure as claimed in claim 1.

18. A method for recovering a multilayer structure, comprising pulverizing and then melt-molding the multilayer structure as claimed in claim 1.

Description

EXAMPLES

[0075] There will be further specifically described the present invention with reference to EXAMPLES.

(1) OTR (Oxygen Transmission Rate) Before Retorting Treatment

[0076] Using the multilayer structures obtained in Examples and Comparative Examples, an oxygen transmission rate was measured where the outer layer (A) was the oxygen supply side while the inner layer (B) was the carrier gas side. Specifically, using an oxygen transmission measuring device (“MOCON OX-TRAN2/21” manufactured by Modern Controls Inc.), an oxygen transmission rate (unit: cc/(m.sup.2.Math.day.Math.atm)) was measured under the conditions: temperature: 20° C., humidity of the oxygen supply side: 65% RH, humidity of the carrier gas side: 65% RH, oxygen pressure: 1 atm and carrier gas pressure: 1 atm. A carrier gas was nitrogen gas containing 2% by volume of hydrogen gas. The results were evaluated on a scale of A to E below. Criteria A to C are sufficient levels for actual use.

Criteria

[0077] A: less than 0.1 cc/(m.sup.2.Math.day.Math.atm)

[0078] B: 0.1 cc/(m.sup.2.Math.day.Math.atm) or more and less than 0.5 cc/(m.sup.2.Math.day.Math.atm)

[0079] C: 0.5 cc/(m.sup.2.Math.day.Math.atm) or more and less than 2 cc/(m.sup.2.Math.day.Math.atm)

[0080] D: 2 cc/(m.sup.2.Math.day.Math.atm) or more and less than 20 cc/(m.sup.2.Math.day.Math.atm)

[0081] E: 20 cc/(m.sup.2.Math.day.Math.atm) or more

(2) OTR (Oxygen Transmission Rate) after Retorting Treatment

[0082] Two multilayer structures obtained in Examples and Comparative Examples were cut out in a 12 cm square pieces, and then the inner layers (B) were overlaid such that these faced each other, and the three sides were heat-sealed to prepare a pouch. Next, 80 g of water was charged through the opening of the pouch, and the opening was heat-sealed to prepare a pouch filled with water. This was retorted at 120° C. for 30 minutes using a retort device (high-temperature high-pressure cooking sterilization tester “RCS-40RTGN” manufactured by Hisaka Works, Ltd.). After the retorting treatment, the water on the surface of the pouch was wiped off, and the pouch was left in a thermo-hygrostat chamber at 20° C. and 65% RH for 3 hours. Then, the pouch was opened to remover water, and then an OTR was measured where the outer layer (A) is an oxygen supply side and the inner layer (B) was a carrier gas side. Specifically, measurement was carried out as described in (1), and the results were also evaluated according to the same criteria, although the criteria were applied to measured values 24 hours after the start of the measurement.

(3) Shading Performance Before and After Retorting Treatment

[0083] A pouch was prepared and retort-treated as described in (2). After the retorting treatment, water on the surface of the pouch was wiped off, and the pouch was left in a thermo-hygrostat chamber at 20° C. and 65% RH for 3 hours. For the multilayer structure thus obtained before and after the retorting treatment, a light transmittance at a wavelength of 600 nm was measured using an ultraviolet visible spectrophotometer “UV-2450” manufactured by Shimadzu Corporation, and evaluated in accordance with the following two-level criteria of A and B. Criterion B is a level unsuitable for actual use in applications that require shading performance.

Criteria

[0084] A: Light transmittance at 600 nm is 10% or less

[0085] B: Light transmittance at 600 nm exceeds 10%

(4) Appearance after Retorting Treatment

[0086] A pouch was prepared and retort-treated as described in (2). After the retorting treatment, water on the surface of the pouch was wiped off, and the pouch was left in a thermo-hygrostat chamber at 20° C. and 65% RH for 3 hours. Then, appearance of the pouch was evaluated in accordance with the following four-level criteria of A to D. Criterion D is a level unsuitable for actual use.

Criteria

[0087] A: Change in appearance was not substantially observed compared to before the retorting treatment.

[0088] B: Mild whitening, discoloration, and deformation were observed.

[0089] C: Moderate whitening, discoloration, and deformation were observed, or partial delamination was observed.

[0090] D: Severe whitening and deformation were observed, or widespread delamination was observed.

(5) Spots and Coloring of a Melt-Molded Product of a Crushed Multilayer Structure

[0091] A multilayer structure obtained in each of Examples and Comparative Examples was pulverized to a size of 4 mm square or less. This crushed product and a polypropylene resin (“Novatec PP EA7AD” manufactured by Japan Polypropylene Corporation (density: 0.90 g/cc, MFR (230° C., under 2.16 kg load): 1.4 g/10 min)) were blended in a mass ratio (crushed product/polypropylene resin) 20/80 and used for monolayer-film formation under the following extrusion conditions, to give a monolayer film with a thickness of 20 μm. A thickness of the monolayer film was adjusted by appropriately changing a screw rotation speed and a take-up roll speed. Using a polypropylene resin alone, a monolayer film with a thickness of 20 μm as a control was prepared as described above.

[0092] Extruder: Uniaxial extruder manufactured by Toyo Seiki Seisakusho, Ltd.

[0093] Screw diameter: 20 mmφ (L/D=20, compression ratio=3.5, full-flight type)

[0094] Extrusion temperature: C1/C2/C3/D=190/230/230/230° C.

[0095] Take-up roll temperature: 80° C.

[0096] The spot and coloring status of the obtained monolayer film was evaluated in accordance with the four-level criteria of A to D. Criterion D is a level unsuitable for actual use.

Criteria for Spots

[0097] A: Compared to the control, the amount of spots was almost the same.

[0098] B: Compared to the control, the amount of small spots was slightly larger.

[0099] C: Compared to the control, the amount of small spots was larger.

[0100] D: Compared to the control, the amount of large spots was larger.

Criteria for Coloring

[0101] A: Compared to the control, a degree of hue change was small (very pale yellow or very pale gray).

[0102] B: Compared to the control, slight coloring was observed (pale yellow or pale gray).

[0103] C: Compared to the control, moderate coloring was observed (yellow or gray).

[0104] D: Compared to the control, significant coloring was observed and furthermore, unevenness was observed.

(6) Melt Viscosity Stability of a Crushed Multilayer Structure

[0105] A multilayer structure obtained in each of Examples and Comparative Examples was pulverized to a size of 4 mm square or less. A torque change when 60 g of this pulverized product was kneaded using a labo plastmill (biaxially different directions) under nitrogen atmosphere at 230° C. and 100 rpm was measured. Torque values (TI and TF, respectively) 10 minutes and 90 minutes after the start of kneading were calculated and evaluated by a TF/TI ratio in accordance with the following four-level criteria of A to D. Criterion D is a level unsuitable for actual use.

Criteria

[0106] A: 80/100 or more and less than 120/100

[0107] B: 60/100 or more and less than 80/100, or 120/100 or more and less than 140/100

[0108] C: 40/100 or more and less than 60/100, or 140/100 or more and less than 160/100

[0109] D: Less than 40/100 or 160/100 or more

Preparation Example 1

[0110] An EVOH resin (not containing polyvalent metal ion, polycarboxylic acid or a hindered phenol compound) having an ethylene content of 32 mol %, a saponification degree of 99.9 mol % and an MFR (210° C., 2.16 kg load) of 3.60 g/10 min was fed to a twin-screw extruder “TEX30a” (screw diameter: 30 mm) manufactured by Japan Steel Works, Ltd. Furthermore, in a twin-screw extruder, an aqueous solution of magnesium acetate as a polyvalent metal salt was added by a liquid addition pump, and to a downstream side to the addition point, extrusion was conducted using a screw in which a forward staggered kneading disk (Forward kneading disk) has L(screw length)/D(screw diameter)=3 as a screw configuration under the conditions of a melting temperature of 220 to 230° C. and an extrusion speed of 20 kg/hr to provide strands. The obtained strands were cooled and solidified in a cooling bath and then cut to provide EVOH pellets containing 150 ppm of magnesium ions.

Preparation Example 2

[0111] EVOH pellets containing 250 ppm of magnesium ions were prepared as described in Preparation Example 1 except that a concentration of the aqueous solution of magnesium acetate was changed.

Preparation Example 3

[0112] EVOH pellets containing 150 ppm of calcium ions were prepared as described in Preparation Example 1, except that an aqueous solution of magnesium acetate was replaced with an aqueous solution of calcium acetate and its concentration was changed.

Preparation Example 4

[0113] EVOH pellets containing 300 ppm of citric acid were prepared as described in Preparation Example 1, except that an aqueous solution of magnesium acetate was replaced with an aqueous solution of citric acid and its concentration was changed.

Preparation Example 5

[0114] EVOH pellets containing 500 ppm of citric acid were prepared as described in Preparation Example 1, except that an aqueous solution of magnesium acetate was replaced with an aqueous solution of citric acid and its concentration was changed.

Preparation Example 6

[0115] EVOH pellets containing 5000 ppm of a hindered phenolic compound having an ester bond were prepared as described in Preparation Example 1, except that in addition to an EVOH resin, a hindered phenolic compound having an ester bond (“Irganox 1010” manufactured by BASF) was fed to a twin-screw extruder.

Preparation Example 7

[0116] EVOH pellets containing 5000 ppm of a hindered phenolic compound having an amide bond were prepared as described in Preparation Example 1, except that in addition to an EVOH resin, a hindered phenolic compound having an amide bond (“Irganox 1098” manufactured by BASF) was fed.

Preparation Example 8

[0117] EVOH pellets containing 15000 ppm of a hindered phenolic compound having an amide bond were prepared as described in Preparation Example 1, except that in addition to an EVOH resin, a hindered phenolic compound having an amide bond (“Irganox 1098” manufactured by BASF) was fed.

Preparation Example 9

[0118] Resin pellets containing EVOH and PA which contains 15 parts of a PA resin based on the total of an EVOH resin and the PA resin as well as 150 ppm of magnesium ions based on the EVOH resin were prepared as described in Preparation Example 1, except that in addition of the EVOH resin, Nylon 6 (UBE NYLON SF1018A) as a PA resin and an aqueous solution of magnesium acetate.

Film Formation Example 1

[0119] An EVOH resin (not containing polyvalent metal ion, polycarboxylic acid or a hindered phenol compound) having an ethylene content of 32 mol %, a saponification degree of 99.9 mol % and an MFR (210° C., 2.16 kg load) of 3.60 g/10 min was extruded under the following extrusion conditions for a monolayer film forming, to provide an monolayer EVOH film with a thickness of 15 μm. A thickness of the monolayer EVOH film was adjusted by appropriately changing a screw rotation speed and a take-up roll speed.

[0120] Extruder: Uniaxial extruder manufactured by Toyo Seiki Seisakusho

[0121] Screw diameter: 20 mmφ (L/D=20, compression ratio=3.5, full flight type)

[0122] Extrusion temperature: C1/C2/C3/D=190/220/220/220° C.

[0123] Take-up roll temperature: 80° C.

Film Formation Example 2

[0124] A monolayer EVOH film with a thickness of 30 μm was prepared as described in Film Formation Example 1 except that a screw rotation speed and a take-up roll speed were changed.

Film Formation Example 3

[0125] A monolayer EVOH film with a thickness of 135 μm was prepared as described in Film Formation Example 1 except that a screw rotation speed and a take-up roll speed were changed. A moisture content of this monolayer EVOH film was adjusted to 15%, and after preheating at 80° C. for 20 seconds, was subjected to simultaneous biaxial stretching under the conditions of a stretching temperature: 80° C. and a drawing ratio: 9 times (3 times in a longitudinal direction and 3 times in a transverse direction) and a stretching speed: 1 m/min using a biaxial stretching device manufactured by Toyo Seiki Seisakusho. Next, the film obtained was fixed to a wooden frame and heated at a temperature of 140° C. for 10 minutes to provide a biaxially stretched monolayer EVOH with a thickness of 15 μm.

Film Formation Example 4

[0126] A three-type three-layer coextruded film (EVOH resin/polypropylene adhesive resin/polypropylene resin=9 μm/9 μm/81 μm) was formed using an EVOH resin (not containing polyvalent metal ions, a polycarboxylic acid, or a hindered phenol compound) with an ethylene content of 48 mol %, a saponification degree of 99.9 mol %, and an MFR (210° C., 2.16 kg load) of 14.8 g/10 min, a polypropylene resin (“Novatec PP EA7AD” manufactured by Japan Polypropylene Corp. (density: 0.90 g/cc, MFR (230° C., under 2.16 kg load) 1.4 g/10 min)) and a polypropylene adhesive resin (“Admer QF500” manufactured by Mitsui Chemicals Inc. (MFR (230° C., under 2.16 kg load): 3.0 g/10 min). The extruder, extrusion conditions, and die used were as follows.

EVOH

[0127] Extruder: Single-screw extruder (Toyo Seiki Co., Ltd., Lab machine type ME CO-EXT)

[0128] Screw: caliber: 20 mmφ, L/D20, full flight screw

[0129] Extrusion temperature: Supply unit/compression unit/measurement unit/die=175/210/220/230° C.

Polypropylene Adhesive Resin

[0130] Extruder: Single-screw extruder (Technovel Corporation, SZW20GT-20MG-STD)

[0131] Screw: caliber: 20 mmφ, L/D20, full flight screw

[0132] Extrusion temperature: Supply unit/compression unit/measurement unit/die=150/200/220/230° C.

Polypropylene Resin

[0133] Extruder: Single-screw extruder (Research Laboratory of Plastics Technology Co., Ltd. GT-32-A)

[0134] Screw: caliber: 32 mmφ, L/D28, full flight screw

[0135] Extrusion temperature: Supply unit/compression unit/measurement unit/die=170/220/230/230° C.

[0136] Die: Coat hanger die for a 300 mm width three-type three-layer (manufactured by Research Laboratory of Plastics Technology Co., Ltd.)

[0137] In Table 1, the polypropylene adhesive resin and the polypropylene resin constituting the coextruded film are collectively referred to as “PP”.

Film Formation Example 5

[0138] A three-type, three-layer co-extruded film (EVOH resin/polypropylene adhesive resin/polypropylene resin=27 μm/27 μm/243 μm) was prepared as described in Film Formation Example 4 except that a screw rotation speed and a take-up roll speed were changed. This co-extruded film was stretched three times in a vertical direction and three times in a horizontal direction at 160° C. by a tenter type simultaneous biaxial stretching facility, to provide a three-type three-layer biaxially stretched co-extruded film (EVOH resin/polypropylene adhesive resin/polypropylene resin=3 μm/3 μm/27 μm).

Film Formation Example 6

[0139] A three-type three-layer coextruded film (EVOH resin/polypropylene adhesive resin/polypropylene resin=6 μm/6 μm/54 μm) was formed as described in Film Formation Example 4, except that a screw rotation speed and a take-up roll speed were changed.

Film Formation Examples 7 to 14

[0140] A monolayer EVOH film with a thickness of 15 μm was prepared as described in Film Formation Example 1 except that the EVOH resin pellets obtained in Preparation Examples 1 to 8 were used.

Film Formation Example 15

[0141] A monolayer EVOH film with a thickness of 15 μm was prepared as described in Film Formation Example 1 except that the resin pellets containing to EVOH and PA obtained in Preparation Example 9 was used and an extrusion temperature was as described below.

[0142] Extrusion temperature: C1/C2/C3/D=230/230/230/230° C.

Example 1

[0143] Aluminum was vacuum-deposited on one side of the monolayer EVOH film obtained in Film Formation Example 1 using “EWA-105” manufactured by Nippon Vacuum Technology Co., Ltd. such that a thickness was 70 nm. Next, a two-part adhesive (“Takelac A-520” and “Takenate A-50” manufactured by Mitsui Chemicals, Inc.) was applied on one side of each of a biaxially stretched polypropylene film (Toyobo Co., Ltd. “Pyrene film-OT P2161”, thickness: 30 μm) and a non-stretched polypropylene film (Tohcello Co., Ltd., “RXC-22”, thickness: 50 μm) such that a dry thickness of the adhesive was 2 μm (hereinafter, sometimes the aluminum vapor deposition layer is abbreviated as VM, the biaxially stretched polypropylene is abbreviated as BOPP, the non-stretched polypropylene film is abbreviated as CPP, and the adhesive layer is abbreviated as Ad).

[0144] Subsequently, the BOPP and CPP coated with the adhesive and the monolayer EVOH film on which aluminum was vapor-deposited were laminated to obtain a multilayer structure having a structure of BOPP30/Ad2/EVOH15NM/Ad2/CPP50 (the number in the symbol representing each layer represents a thickness in μm of the layer). Here, in the monolayer EVOH film on which aluminum was vapor-deposited, the aluminum-deposited layer was on the CPP side and the EVOH layer was on the BOPP side. The evaluation in (1) to (6) above was performed using the multilayer structure. The results are shown in Table 2.

Examples 2 to 8, 11, 12, 15 to 23 and Comparative Examples 4, 7

[0145] A multilayer structure was prepared as described in Example 1, except that the layer structure of the multilayer structure was changed as shown in Table 1. In Examples 6, 7, 9 and 10, the coextruded film obtained in any of Film Forming Examples 4 to 6 was used instead of the monolayer EVOH film. In this case, aluminum was vapor-deposited on the EVOH side surface of the co-extruded film. The multilayer structure obtained was evaluated as described in Example 1. The evaluation results are shown in Table 2. Here, each layer used for the multilayer structure shown in Table 1 is as follows.

[0146] BOPP20: biaxially stretched polypropylene film (“Pylen Film-OT P2161” manufactured by Toyobo Co., Ltd., melting point: 164° C., thickness: 20 μm)

[0147] BOPP30: biaxially stretched polypropylene film (“Pylen Film-OT P2161” manufactured by Toyobo Co., Ltd., melting point: 164° C., thickness: 30 μm)

[0148] BOPP50: biaxially stretched polypropylene film (“Pylen Film-OT P2161” manufactured by Toyobo Co., Ltd., melting point: 164° C., thickness: 50 μm)

[0149] CPP30: non-stretched polypropylene film (“Torayfan NO 3951” manufactured by Toray Industries, Inc., melting point: 144° C., thickness: 30 μm)

[0150] CPP50: non-stretched polypropylene film (“RXC-22” manufactured by Tohcello Co., Ltd., melting point: 166° C., thickness: 50 μm)

[0151] CPP100: non-stretched polypropylene film (“RXC-22” manufactured by Tohcello Co., Ltd., melting point: 166° C., thickness: 100 μm)

[0152] BOPET12: stretched polyethylene terephthalate film (“Lumirror P60” manufactured by Toray Industries, Inc., melting point: 256° C., thickness: 12 μm)

[0153] PE50: non-stretched polyethylene film (“T.U.X. HZR-2” manufactured by Tohcello Co., Ltd., melting point: 127° C., thickness: 50 μm)

[0154] Al9: aluminum foil (thickness: 9 μm)

[0155] In Table 1, considering the order of the aluminum-deposited layer and the layer on which aluminum is vapor-deposited, they are represented as, for example, “VM/EVOH” or “EVOH/VM”. For example, in the multilayer structure of Example 1, it is shown that the layers are laminated such that the VM layer is the inner layer side and the EVOH layer is the outer layer side. Such a notation also applies to the other aluminum vapor deposition layers.

[0156] Furthermore, in Table 1, for the multilayer structure having the coextruded films obtained in Film Formation Examples 4 to 6, a portion composed of the coextruded film is represented in parentheses as, for example, (PP90/EVOH9). Here, “BO” means that it is a biaxially stretched film.

Example 9

[0157] Aluminum was vacuum-deposited on the surface of the EVOH resin side of the biaxially stretched coextruded film obtained in Film Formation Example 5 using “EWA-105” manufactured by Nippon Vacuum Technology Co., Ltd., such that a thickness was 70 nm. Next, a two-part adhesive (“Takelac A-520” and “Takenate A-50” manufactured by Mitsui Chemicals, Inc.) was applied to one side of the CPP50 to such an amount that a dry thickness was to be 2 μm and then dried.

[0158] Subsequently, the CPP50 coated with the adhesive and the biaxially stretched coextruded film on which aluminum was vapor-deposited were laminated to provide a multilayer structure having a structure of BO(PP30/EVOH3)NM/Ad2/CPP50. The multilayer structure thus obtained was evaluated as described in Example 1. The evaluation results are shown in Table 2.

Example 10

[0159] Aluminum was vacuum-deposited on the surface of the EVOH resin side of the coextruded film obtained in Film Formation Example 6 using “EWA-105” manufactured by Nippon Vacuum Technology Co., Ltd., such that a thickness was 70 nm. Next, a two-part adhesive (“Takelac A-520” and “Takenate A-50” manufactured by Mitsui Chemicals, Inc.) was applied to one side of the OPP30 to such an amount that a dry thickness was to be 2 μm and then dried.

[0160] Subsequently, the OPP30 coated with the adhesive and the coextruded film on which aluminum was vapor-deposited were laminated to provide a multilayer structure having a structure of BOPP30/Ad2NM/(EVOH6/PP60). The multilayer structure thus obtained was evaluated as described in Example 1. The evaluation results are shown in Table 2.

Example 13

[0161] Aluminum was vacuum-deposited on one side of BOPP30 using “EWA-105” manufactured by Nippon Vacuum Technology Co., Ltd., such that a thickness was 70 nm. Next, a two-part adhesive (“Takelac A-520” and “Takenate A-50” manufactured by Mitsui Chemicals, Inc.) was applied to the aluminum vapor-deposited side of BOPP30 and one side of the CPP50 to such an amount that a dry thickness was to be 2 μm and then dried.

[0162] Subsequently, the BOPP30 and the CPP50 on which aluminum were vapor-deposited and which were coated with the adhesive as well as the monolayer EVOH film were laminated to provide a multilayer structure having a structure of BOPP30/VM/Ad2/EVOH15/Ad2/CPP50. The multilayer structure thus obtained was evaluated as described in Example 1. The evaluation results are shown in Table 2.

Example 14

[0163] Aluminum was vacuum-deposited on one side of CPP50 using “EWA-105” manufactured by Nippon Vacuum Technology Co., Ltd., such that a thickness was 70 nm. Next, a two-part adhesive (“Takelac A-520” and “Takenate A-50” manufactured by Mitsui Chemicals, Inc.) was applied to the aluminum vapor-deposited side of CPP50 and one side of the BOPP30 to such an amount that a dry thickness was to be 2 μm and then dried.

[0164] Subsequently, the CPP50 and the BOPP30 on which aluminum were vapor-deposited and which were coated with the adhesive as well as the monolayer EVOH film were laminated to provide a multilayer structure having a structure of BOPP30/Ad2/EVOH15/Ad2NM/CPP50. The multilayer structure thus obtained was evaluated as described in Example 1. The evaluation results are shown in Table 2.

Comparative Example 1

[0165] A two-part adhesive (“Takelac A-520” and “Takenate A-50” manufactured by Mitsui Chemicals, Inc.) was applied to one side of the BOPP30 to such an amount that a dry thickness was to be 2 μm and then dried. Then, this and the CPP50 were laminated to provide a multilayer structure which having neither a barrier resin layer (C) nor a metal deposited layer (D). The multilayer structure thus obtained was evaluated as described in Example 1. The evaluation results are shown in Table 2.

Comparative Example 2

[0166] A multilayer structure having no metal deposited layers (D) was provided as described in Example 1, except that aluminum was not vapor-deposited on the monolayer EVOH film obtained in Film Formation Example 1. The multilayer structure thus obtained was evaluated as described in Example 1. The evaluation results are shown in Table 2.

Comparative Example 3

[0167] Aluminum was vacuum-deposited on one side of BOPP30 using “EWA-105” manufactured by Nippon Vacuum Technology Co., such that a thickness was 70 nm. Then, a two-part adhesive (“Takelac A-520” and “Takenate A-50” manufactured by Mitsui Chemicals, Inc.) was applied to one side of the CPP50 to such an amount that a dry thickness was to be 2 μm and then dried.

[0168] Subsequently, the CPP50 coated with the adhesive and the BOPP30 on which aluminum was vapor-deposited were laminated to provide a multilayer structure having a structure of BOPP30/VM/Ad2/CPP50. The multilayer structure thus obtained was evaluated as described in Example 1. The evaluation results are shown in Table 2.

Comparative Example 5

[0169] A two-part adhesive (“Takelac A-520” and “Takenate A-50” manufactured by Mitsui Chemicals, Inc.) was applied to one side of BOPET12 to such an amount that a dry thickness was to be 2 μm and then dried. This and BOPP30 were laminated. The above two-part adhesive was applied on the surface of the BOPET12 side and on one side of CPP100, respectively, in such an amount that a dry thickness was to be 2 μm, and dried.

[0170] Subsequently, the laminate and the CPP100 which were coated with the adhesive as well as the above monolayer EVOH film on which aluminum was vapor-deposited were laminated, to provide a multilayer having a structure of BOPP30/Ad2/BOPET12/Ad2/EVOH15NM/Ad2/CPP100. The multilayer structure thus obtained was evaluated as described in Example 1. The evaluation results are shown in Table 2.

Comparative Example 6

[0171] A two-part adhesive (“Takelac A-520” and “Takenate A-50” manufactured by Mitsui Chemicals, Inc.) was applied to one side of BOPP30 to such an amount that a dry thickness was to be 2 μm and then dried. This and Al9 were laminated. The above two-part adhesive was applied on the surface of the Al9 side and on one side of CPP100, respectively, in such an amount that a dry thickness was to be 2 μm, and dried.

[0172] Subsequently, the laminate and the CPP100 which were coated with the adhesive as well as the above monolayer EVOH film on which aluminum was vapor-deposited were laminated, to provide a multilayer having a structure of BOPP30/Ad2/Al9/Ad2/EVOH15NM/Ad2/CPP100. The multilayer structure thus obtained was evaluated as described in Example 1. The evaluation results are shown in Table 2.

TABLE-US-00001 TABLE 1 Barrier resin layer (C) EVOH (c) Metal Hindered vapor Polyvalent Polycarboxylic phenolic deposition Ethylene metal ion acid compound layer unit (e) (f) (g) PA (D) content Content Content Content (h) Thickness mol % Type ppm Type ppm Type ppm Type Content* nm Example 32 — — — — — — — — 70 1 Example 32 — — — — — — — — 70 2 Example 32 — — — — — — — — 70 3 Example 32 — — — — — — — — 70 4 Example 32 — — — — — — — — 70 5 Example 48 — — — — — — — — 70 6 Example 48 — — — — — — — — 70 7 Example 32 — — — — — — — — 70 8 Example 48 — — — — — — — — 70 9 Example 48 — — — — — — — — 70 10 Example 32 — — — — — — — — 50 11 Example 32 — — — — — — — — 90 12 Example 32 — — — — — — — — 70 13 Example 32 — — — — — — — — 70 14 Example 32 Mg 150 — — — — — — 70 15 Example 32 Mg 250 — — — — — — 70 16 Example 32 Ca 150 — — — — — — 70 17 Example 32 — — Citric 300 — — — — 70 18 acid Example 32 — — Citric 500 — — — — 70 19 acid Example 32 — — — — Ester  5000 — — 70 20 Example 32 — — — — Amide  5000 — — 70 21 Example 32 — — — — Amide 15000 — — 70 22 Example 32 Mg 150 — — — — PA6 85/15 70 23 Comparative — — — — — — — — — — Example 1 Comparative 32 — — — — — — — — — Example 2 Comparative — — — — — — — — — 70 Example 3 Comparative 32 — — — — — — — — 70 Example 4 Comparative 32 — — — — — — — — 70 Example 5 Comparative 32 — — — — — — — — 70 Example 6 Comparative 32 — — — — — — — — 70 Example 7 Multilayer structure Film forming Layer method structure of a layer Total Total (Outer layer containing thickness thickness Thickness (A) side - a barrier Total of metal of PP ratio Inner layer resin layer thickness layers layers of PP (B) side) (C) μm μm μm layers Example BOPP30/Ad2/EVOH15/ Film 99 0.07 80 0.81 1 VM/Ad2/CPP50 Formation Example 1 Example BOPP50/Ad2/EVOH15/ Film 169 0.07 150 0.89 2 VM/Ad2/CPP100 Formation Example 1 Example BOPP20/Ad2/EVOH15/ Film 69 0.07 50 0.72 3 VM/Ad2/PP30 Formation Example 1 Example BOPP30/Ad2/EVOH30/ Film 114 0.07 80 0.70 4 VM/Ad2/CPP50 Formation Example 2 Example BOPP30/Ad2/BOEVOH15/ Film 99 0.07 80 0.81 5 VM/Ad2/CPP50 Formation Example 3 Example BOPP30/Ad2/(PP90/ Film 183 0.07 170 0.93 6 EVOH9)/VM/Ad2/CPP50 Formation Example 4 Example BOPP30/Ad2/BO(PP30/ Film 117 0.07 110 0.94 7 EVOH3)/VM/Ad2/CPP50 Formation Example 5 Example BOPP30/Ad2/VM/ Film 99 0.07 80 0.81 8 EVOH15/Ad2/CPP50 Formation Example 1 Example BO(PP30/EVOH3)/VM/ Film 85 0.07 80 0.94 9 Ad2/CPP50 Formation Example 5 Example BOPP30/Ad2/VM/ Film 131 0.07 120 0.92 10 (EVOH6/PP60) Formation Example 6 Example BOPP30/Ad2/EVOH15/ Film 99 0.05 80 0.81 11 VM/Ad2/CPP50 Formation Example 1 Example BOPP30/Ad2/EVOH15/ Film 99 0.09 80 0.81 12 VM/Ad2/CPP50 Formation Example 1 Example BOPP30/VM/Ad2/ Film 99 0.07 80 0.81 13 EVOH15/Ad2/CPP50 Formation Example 1 Example BOPP30/Ad2/EVOH15/ Film 99 0.07 80 0.81 14 Ad2/VM/CPP50 Formation Example 1 Example BOPP30/Ad2/EVOH15/ Film 99 0.07 80 0.81 15 VM/Ad2/CPP50 Formation Example 7 Example BOPP30/Ad2/EVOH15/ Film 99 0.07 80 0.81 16 VM/Ad2/CPP50 Formation Example 8 Example BOPP30/Ad2/EVOH15/ Film 99 0.07 80 0.81 17 VM/Ad2/CPP50 Formation Example 9 Example BOPP30/Ad2/EVOH15/ Film 99 0.07 80 0.81 18 VM/Ad2/CPP50 Formation Example 10 Example BOPP30/Ad2/EVOH15/ Film 99 0.07 80 0.81 19 VM/Ad2/CPP50 Formation Example 11 Example BOPP30/Ad2/EVOH15/ Film 99 0.07 80 0.81 20 VM/Ad2/CPP50 Formation Example 12 Example BOPP30/Ad2/EVOH15/ Film 99 0.07 80 0.81 21 VM/Ad2/CPP50 Formation Example 13 Example BOPP30/Ad2/EVOH15/ Film 99 0.07 80 0.81 22 VM/Ad2/CPP50 Formation Example 14 Example BOPP30/Ad2/EVOH + Film 99 0.07 80 0.81 23 PA15/VM/Ad2/CPP50 Formation Example 15 Comparative BOPP30/Ad2/CPP50 — 82 — 80 0.98 Example 1 Comparative BOPP30/Ad2/EVOH15/ Film 99 — 80 0.81 Example 2 Ad2/CPP50 Formation Example 1 Comparative BOPP30/VM/Ad2/CPP50 — 82 0.07 80 0.98 Example 3 Comparative BOPET12/Ad2/EVOH15/ Film 131 0.07 100 0.76 Example 4 VM/Ad2/CPP100 Formation Example 1 Comparative BOPP30/Ad2/BOPET12/ Film 163 0.07 130 0.80 Example 5 Ad2/EVOH15/VM/Ad2/ Formation CPP100 Example 1 Comparative BOPP30/Ad2/AI9/Ad2/ Film 160 9.07 130 0.81 Example 6 EVOH15/VM/Ad2/CPP100 Formation Example 1 Comparative PE50/Ad2/EVOH15/VM/ Film 169 0.07 100 0.59 Example 7 Ad2/CPP100 Formation Example 1 *Mass ratio (c/h) of EVOH (c) to PA(h)

TABLE-US-00002 TABLE 2 OTR (20° C., 65% RH) Molten molded product of a cc/(m.sup.2 .Math. day .Math. atm) Shading performance pulverized multilayer structure Before After Before After Appearance Viscosity retorting retorting retorting retorting after retorting Spots Coloring stability Example 1 A B A A B B B B Example 2 A A A A A A A A Example 3 A C A A C C C C Example 4 A B A A C C C C Example 5 A A A A B B B B Example 6 A C A A B A A A Example 7 A B A A B A A A Example 8 A C A A C B B B Example 9 A C A A C A A A Example 10 A C A A C A A A Example 11 A C A A C B A B Example 12 A A A A A B C B Example 13 A C A A B B B B Example 14 A C A A B B B B Example 15 A B A A B A B A Example 16 A B A A B A C A Example 17 A B A A B B B A Example 18 A B A A B B A B Example 19 A B A A B C A C Example 20 A B A A B A B B Example 21 A B A A B A B B Example 22 A B A A B A C A Example 23 A A A A A B B A Comparative E E B B A A A A Example 1 Comparative B E B B C B A B Example 2 Comparative C E A A B A B A Example 3 Comparative A D A A C D B B Example 4 Comparative A B A A B D B B Example 5 Comparative A A A A A D D D Example 6 Comparative A D A A D B B B Example 7