Multilayer Structure, Method for Producing Same, Packaging Material and Product Including Same, and Protective Sheet for Electronic Device

Abstract

The present invention provides a multilayer structure that has excellent gas barrier properties and an excellent peel strength between a base and a gas barrier layer after retorting, and that can retain a good appearance with no delamination even after retorting under stress. The present invention also provides packaging materials and products including such a multilayer structure. The present invention relates to a multilayer structure comprising a base (X), a layer (Z) stacked on the base (X), and a layer (Y) stacked on the layer (Z), the layer (Y) containing a reaction product (D) of an aluminum-containing metal oxide (A) and an inorganic phosphorus compound (BI), the layer (Z) containing a polyvinyl alcohol resin (C) and a polyester resin (L).

Claims

1. A multilayer structure comprising a base (X), a layer (Z) stacked on the base (X), and a layer (Y) stacked on the layer (Z), the layer (Y) containing a reaction product (D) of an aluminum-containing metal oxide (A) and an inorganic phosphorus compound (BI), the layer (Z) containing a polyvinyl alcohol resin (C) and a polyester resin (L).

2. The multilayer structure according to claim 1, wherein the polyester resin (L) is a polyester resin having a carboxyl group.

3. The multilayer structure according to claim 1, wherein a mass ratio(C)/(L) of the polyvinyl alcohol resin (C) and the polyester resin (L) is 1/99 to 50/50.

4. The multilayer structure according to claim 1, wherein the polyvinyl alcohol resin (C) has a viscosity in a 4 mass % aqueous solution of 1 mPa.Math.s to 100 mPa.Math.s as measured in accordance with JIS K 6726 (1994).

5. The multilayer structure according to claim 1, wherein the layer (Z) has a thickness ranging from 1 to 100 nm.

6. The multilayer structure according to claim 1, wherein the base (X) and the layer (Y) have an interlayer peel strength of 100 gf/15 mm or more as measured while dropping water on a delaminating interface after 125° C., 30-minute retorting.

7. A method for producing a multilayer structure of claim 1, comprising: a step (I) of applying a coating liquid (R) containing a polyvinyl alcohol resin (C), a polyester resin (La), and a solvent to a base (X), and removing the solvent to form a layer (Z); a step (II) of applying a coating liquid (S) containing an aluminum-containing metal oxide (A), an inorganic phosphorus compound (BI), and a solvent to the layer (Z), and removing the solvent to form a precursor of layer (Y); and a step (III) of heat treating the precursor of layer (Y) to form a layer (Y).

8. A packaging material comprising a multilayer structure of claim 1.

9. The packaging material according to claim 8, which is a vertical form-fill-seal bag, a vacuum packaging bag, a pouch, a laminated tube container, an infusion bag, a paper container, a strip tape, a container lid, or an in-mold labeled container.

10. A product using a packaging material of claim 8 in at least a part of the product.

11. The product according to claim 10, wherein the product comprises contents in an interior thereof, the contents are a core material, the interior of the product has a reduced pressure, and the product functions as a vacuum insulator.

12. A protective sheet for electronic devices, comprising a multilayer structure of claim 1.

13. An electronic device comprising a protective sheet of claim 12.

Description

EXAMPLES

[0256] The following describes the present invention in greater detail by way of Examples. It should be noted that the present invention is in no way limited by the following Examples, and various changes may be made by a person with ordinary skill in the art within the technical idea of the present invention.

[0257] Materials Used in Examples and Comparative Examples PVA resin (C)

[0258] C-1: Kuraray Poval® 60-98 (manufactured by Kuraray Co., Ltd., PVA, degree of saponification 98.0 to 99.0 mol %, viscosity (4 mass %, 20° C.) 54.0 to 66.0 mPa.Math.s)

[0259] C-2: Kuraray Poval® 5-98 (manufactured by Kuraray Co., Ltd., PVA, degree of saponification 98.0 to 99.0 mol %, viscosity (4 mass %, 20° C.) 5.2 to 6.0 mPa.Math.s)

[0260] C-3: Kuraray Poval® 5-82 (manufactured by Kuraray Co., Ltd., PVA, degree of saponification 80.0 to 83.0 mol %, viscosity (4 mass %, 20° C.) 4.5 to 5.2 mPa.Math.s)

[0261] C-4: Kuraray Poval® 48-80 (manufactured by Kuraray Co., Ltd., PVA, degree of saponification 78.5 to 80.5 mol %, viscosity (4 mass %, 20° C.) 45.0 to 51.0 mPa.Math.s)

[0262] Aqueous dispersion of polyester resin (La)

[0263] La-1: Elitel® KA-5071S (manufactured by Unitika Ltd., polyester-based aqueous dispersion, solids concentration 30 mass %)

[0264] La-2: Pesresin® A-684G (manufactured by Takamatsu Oil and Fat Co., Ltd., an aqueous dispersion of polyester-acryl composite resin, containing about 40% acrylic resin component)

Film

[0265] PET 12: Oriented polyethylene terephthalate film; manufactured by Toray Industries, Inc. under the trade name Lumirror™ P60, thickness=12 μm

[0266] PET 50: Polyethylene terephthalate film with improved adhesion to ethylene-vinyl acetate copolymer; manufactured by TOYOBO CO., LTD. under the trade name SHINEBEAM™ Q1A15, thickness=50 μm

[0267] ONY 15: Oriented nylon film; manufactured by Unitika Ltd. under the trade name EMBLEM™ ONBC, thickness=15 μm

[0268] CPP 50: Non-oriented polypropylene film; manufactured by Mitsui Chemicals Tohcello, Inc. under the trade name RXC-22, thickness=50 μm

[0269] CPP 70: Non-oriented polypropylene film; manufactured by Mitsui Chemicals Tohcello, Inc. under the trade name RXC-22, thickness=70 μm

[0270] CPP 100: Non-oriented polypropylene film; manufactured by Mitsui Chemicals Tohcello, Inc. under the trade name RXC-22, thickness=100 μm

[0271] VM-XL: Aluminum deposited biaxially oriented EVOH; VM-XL, manufactured by Kuraray Co., Ltd., thickness=15 μm, the order of layers is Al deposited layer/EVOH layer, unless otherwise specifically stated

[0272] Two-component adhesive: TAKE LAC® A-520 (brand name) and TAKENATE® A-50 (brand name), manufactured by Mitsui Chemicals Inc.

[0273] Evaluation Methods

(1) Thickness of Layer (Z)

[0274] The multilayer structure obtained in each Example and Comparative Example was cut using a focused ion beam (FIB) to prepare a section for cross-sectional observation. The prepared section was secured to a sample stage with a carbon tape, and was subjected to platinum ion sputtering at an accelerating voltage of 30 kV for 30 seconds. The cross-section of the multilayer structure was observed using a field-emission transmission electron microscope, and the thickness of layer (Z) was calculated. The measurement conditions are as follows.

[0275] Apparatus: JEM-2100F, manufactured by JEOL Ltd.

[0276] Accelerating voltage: 200 kV

[0277] Magnification: 250,000×

(2) Retort Test under Stress

[0278] Two of the multilayer structures obtained in each Example and Comparative Example were overlaid to face each other on the CPP 50 surfaces, and were heated at 130° C. to form a laminate. After cutting out a 160 mm×40 mm strip from the laminate, a total of 14 holes, each measuring 6 mm in diameter, were formed along the strip in two rows, 7 holes in each row, at 20 mm intervals from the end. The strip was then rolled from the longer side at an 8.5 mm curvature radius, and the ends were secured with a stapler to form a cylindrical shape. The cylinder was subjected to retorting (hot water retaining method) under the following conditions.

[0279] Retorting apparatus: Flavor Ace RSC-60, manufactured by HISAKA WORKS, LTD.

[0280] Temperature: 125° C.

[0281] Time: 30 minutes

[0282] Pressure: 0.17 MPaG

[0283] After retorting, the cylinder was checked for the presence or absence of peeling around the 6 mm holes, and evaluated as “A” when it had at most 2 peeled holes, “B” when it had 3 to 7 peeled holes, and “C” when it had 8 or more peeled holes.

(3) Oxygen Transmission Rate and Peel Strength after Retorting

[0284] The multilayer structure obtained in each Example and Comparative Example was cut into a 120 mm×120 mm size, and heat sealed on three sides to prepare a pouch sealed on three sides. The pouch was then filled with 100 g of water from the non-sealed side, and this side was heat sealed to obtain a pouch containing 100 g of water. The pouch was subjected to retorting (hot water retaining method) under the following conditions.

[0285] Retorting apparatus: Flavor Ace RSC-60, manufactured by HISAKA WORKS, LTD.

[0286] Temperature: 125° C.

[0287] Time: 30 minutes

[0288] Pressure: 0.17 MPaG

[0289] After retorting, the pouch was cooled to room temperature, and one surface was cut into a 10 mm×10 mm size after wiping off water from the surface.

The cut portion of the pouch was then set on an oxygen transmission rate measurement apparatus in such an orientation that the base (X) was on the carrier gas side, and the oxygen transmission rate was measured by an equal pressure method. The measurement conditions are as follows.

[0290] Apparatus: MOCON OX-TRAN 2/21, manufactured by MOCON

[0291] Temperature: 20° C.

[0292] Humidity on oxygen feed side: 85% RH

[0293] Humidity on carrier gas side: 85% RH

[0294] Carrier gas flow rate: 10 mUmin

[0295] Oxygen pressure: 1.0 atm

[0296] Carrier gas pressure: 1.0 atm

[0297] Immediately after retorting, the multilayer structure was cut out from the pouch, and subjected to a T-peel strength measurement according to JIS K 6854-3:1999 (adhesion per 15 mm width) to measure wet-state interlayer peel strength. The measurement was conducted 5 times, and the mean value was calculated. Here, “wet-state interlayer peel strength” refers to a peel strength between layers measured soon after wiping off surface water immediately following retorting. The measurement conditions are as follows.

[0298] Apparatus: Autograph AGS-H, Shimadzu Corporation

[0299] Peel rate: 250 mm/min

[0300] Temperature: 23° C.

[0301] Humidity: 50% RH

[0302] Separately, a wetted interlayer peel strength was measured in the same fashion by conducting the same peel strength measurement, except that the peel strength was measured while dropping ion-exchange water on the delaminating interface with a dropper.

[0303] Production Example of Coating Liquid (R-1)

[0304] A PVA Kuraray Poval® 60-98 (4.8 parts by mass) and water (95.2 parts by mass) were mixed, and the mixture was stirred in an 80° C. water bath for 5 hours to dissolve the Kuraray Poval® 60-98 and obtain a PVA aqueous solution (1-1). Thereafter, 0.8 parts by mass of polyester-based aqueous dispersion Elitel® KA-5071S (manufactured by Unitika Ltd.), 1.2 parts by mass of PVA aqueous solution (1-1), 68.1 parts by mass of water, and 29.9 parts by mass of methanol were mixed, and the mixture was stirred for 1 hour to obtain a coating liquid (R-1).

[0305] Production Example of Coating Liquid (R-2)

[0306] A coating liquid (R-2) was obtained in the same manner as in Production Example of coating liquid (R-1), except that Kuraray Poval® 5-98 was used instead of Kuraray Poval® 60-98.

[0307] Production Example of Coating Liquid (R-3)

[0308] A PVA Kuraray Poval® 5-82 (4.8 parts by mass) and water (95.2 parts by mass) were mixed, and the mixture was stirred at room temperature for 5 hours to dissolve the Kuraray Poval® 5-82 and obtain a PVA aqueous solution (1-2). Thereafter, 0.8 parts by mass of polyester-based aqueous dispersion Elitel® KA-5071S (manufactured by Unitika Ltd.), 1.2 parts by mass of PVA aqueous solution (1-2), 68.1 parts by mass of water, and 29.9 parts by mass of methanol were mixed, and the mixture was stirred for 1 hour to obtain a coating liquid (R-3).

[0309] Production Example of Coating Liquid (R-4)

[0310] A coating liquid (R-4) was obtained in the same manner as in Production Example of coating liquid (R-3), except that Kuraray Poval® 48-80 was used instead of Kuraray Poval® 5-82.

[0311] Production Example of Coating Liquid (R-5)

[0312] A PVA Kuraray Poval® 60-98 (4.8 parts by mass) and water (95.2 parts by mass) were mixed, and the mixture was stirred in an 80° C. water bath for 5 hours to dissolve the Kuraray Poval® 60-98 and obtain a PVA aqueous solution (1-1). Thereafter, 2.2 parts by mass of ester-based aqueous dispersion Pesresin A-684G (manufactured by Takamatsu Oil and Fat Co., Ltd.), 1.2 parts by mass of PVA aqueous solution (1-1), 66.8 parts by mass of water, and 29.8 parts by mass of methanol were mixed, and the mixture was stirred for 1 hour to obtain a coating liquid (R-5).

[0313] Production Example of Coating Liquid (R-6)

[0314] A coating liquid (R-6) was obtained in the same manner as in Production Example of coating liquid (R-5), except that Kuraray Poval® 5-98 was used instead of Kuraray Poval® 60-98.

[0315] Production Example of Coating Liquid (R-7)

[0316] A PVA Kuraray Poval® 5-82 (4.8 parts by mass) and water (95.2 parts by mass) were mixed, and the mixture was stirred at room temperature for 5 hours to dissolve the Kuraray Poval® 5-82 and obtain a PVA aqueous solution (1-2). Thereafter, 2.2 parts by mass of ester-based aqueous dispersion Pesresin A-684G (manufactured by Takamatsu Oil and Fat Co., Ltd.), 1.2 parts by mass of PVA aqueous solution (1-2), 66.8 parts by mass of water, and 29.8 parts by mass of methanol were mixed, and the mixture was stirred for 1 hour to obtain a coating liquid (R-7).

[0317] Production Example of Coating Liquid (R-8)

[0318] A coating liquid (R-8) was obtained in the same manner as in Production Example of coating liquid (R-7), except that Kuraray Poval® 48-80 was used instead of Kuraray Poval® 5-82.

[0319] Production Example of Coating Liquid (CR-1)

[0320] A polyester-based aqueous dispersion Elitel® KA-5071S (1.0 part by mass; manufactured by Unitika Ltd.), water (69.0 parts by mass), and methanol (30.0 parts by mass) were mixed, and the mixture was stirred for 1 hour to obtain a coating liquid (CR-1).

[0321] Production Example of Coating Liquid (CR-2)

[0322] An ester-based aqueous dispersion Pesresin A-684G (2.4 parts by mass; manufactured by Takamatsu Oil and Fat Co., Ltd.), water (67.8 parts by mass) , and methanol (29.8 parts by mass) were mixed, and the mixture was stirred for 1 hour to obtain a coating liquid (CR-2).

[0323] Production Example of Coating Liquid (CR-3)

[0324] A PVA Kuraray Poval® 60-98 (4.8 parts by mass) and water (95.2 parts by mass) were mixed, and the mixture was stirred in an 80° C. water bath for 5 hours to dissolve the Kuraray Poval® 60-98 and obtain a PVA aqueous solution (1-1). Thereafter, 0.3 parts by mass of PVA aqueous solution (1-1), 69.8 parts by mass of water, and 29.9 parts by mass of methanol were mixed, and the mixture was stirred for 1 hour to obtain a coating liquid (CR-3).

[0325] Production Example of Coating Liquid (CR-4)

[0326] A coating liquid (CR-4) was obtained in the same manner as in Production Example of coating liquid (CR-3), except that Kuraray Poval® 5-98 was used instead of Kuraray Poval® 60-98.

[0327] Production Example of Coating Liquid (CR-5)

[0328] A PVA Kuraray Poval® 5-82 (4.8 parts by mass) and water (95.2 parts by mass) were mixed, and the mixture was stirred at room temperature for 5 hours to dissolve the Kuraray Poval® 5-82 and obtain a PVA aqueous solution (1-2). Thereafter, 0.3 parts by mass of PVA aqueous solution (1-2), 69.8 parts by mass of water, and 29.9 parts by mass of methanol were mixed, and the mixture was stirred for 1 hour to obtain a coating liquid (CR-5).

[0329] Production Example of Coating Liquid (CR-6)

[0330] A coating liquid (CR-6) was obtained in the same manner as in Production Example of coating liquid (CR-5), except that Kuraray Poval® 48-80 was used instead of Kuraray Poval® 5-82.

[0331] Production Example of Coating Liquid (S-1)

[0332] Distilled water in an amount of 230 parts by mass was heated to 70° C. under stirring. Triisopropoxyaluminum in an amount of 88 parts by mass was added dropwise to the distilled water over 1 hour, the liquid temperature was gradually increased to 95° C., and isopropanol generated was distilled off. In this manner, hydrolytic condensation was performed. To the resulting liquid was added 4.0 parts by mass of a 60 mass % aqueous nitric acid solution, and this was followed by stirring at 95° C. for 3 hours to deflocculate agglomerates of particles of the hydrolytic condensate. After that, the liquid was concentrated so that the concentration of solids calculated as aluminum oxide was adjusted to 10 mass %. To 22.50 parts by mass of the solution thus obtained were added 54.29 parts by mass of distilled water and 18.80 parts by mass of methanol. This was followed by stirring to obtain a homogeneous dispersion. Subsequently, 4.41 parts by mass of an 85 mass % aqueous phosphoric acid solution was added dropwise to the dispersion under stirring, with the liquid temperature held at 15° C. The stirring was continued at 15° C. until a viscosity of 1,500 mPa.Math.s was reached. The intended coating liquid (S-1) was thus obtained. In the coating liquid (S-1), the molar ratio between aluminum atoms and phosphorus atoms, as expressed by [aluminum atoms]:[phosphorus atoms], was 1.15:1.00.

Example 1

Example 1-1

[0333] First, a PET 12 (which may hereinafter be abbreviated as “X-1”) was prepared as the base (X). The coating liquid (R-1) was applied onto the base with a bar coater in a thickness that becomes 10 nm after drying. The film of the applied liquid was dried at 140° C. for 1 minute to form a layer (Z-1) on the base. Thereafter, the coating liquid (S-1) was applied with a bar coater in a thickness that becomes 0.3 μm after drying. The film of the applied liquid was dried at 120° C. for 3 minutes to form a precursor of layer (Y-1) on the layer (Z-1). This produced a structure having a configuration of base (X-1)/layer (Z-1)/a precursor of layer (Y-1). The structure was heat treated at 180° C. for 1 minute to form a layer (Y-1). This produced a multilayer structure (1-1-1) having a configuration of base (X-1)/layer (Z-1)/layer (Y-1). Thereafter, an adhesive layer was formed on the layer (Y) of the multilayer structure (1-1-1), and an ONY15 was laminated on the adhesive layer to form a laminate. After forming another adhesive layer on the ONY 15, a CPP 50 was laminated on the adhesive layer, and the laminate was left to stand at 40° C. for 5 days for aging. This produced a multilayer structure (1-1-2) having a configuration of base (X)/layer (Z)/layer (Y)/adhesive layer/ONY/adhesive layer/CPP. Each of the two adhesive layers was formed by applying the two-component adhesive (TAKELAC® and TAKENATE®) with a bar coater in a thickness that becomes 3 μm after drying, and drying the adhesive. The multilayer structure (1-1-2) was measured for thickness of layer (Z), retort resistance under stress, and post-retort oxygen transmission rate and peel strength according to the evaluation methods (1) to (3) described above. The evaluation results are presented in Table 1.

Examples 1-2 to 1-16 and Comparative Examples 1-1 to 1-7

[0334] Multilayer structures (1-2-2) to (1-16-2) and multilayer structures (C1-1-2) to (C1-7-2) were produced and evaluated in the same manner as in Example 1-1, except that the type of coating liquid and the thickness of layer (Z) were varied as shown in Table 1. The results are presented in Table 1.

Comparative Examples 1-8

[0335] Multilayer structures (C1-8-1) and (C1-8-2) were produced and evaluated in the same manner as in Example 1-1, except that a deposited layer of aluminum, 0.08 μm thick, was used as layer (Y). The results are presented in Table 1.

TABLE-US-00001 TABLE 1 Aqueous Blend Viscosity of Multilayer Layer (Z) Thickness PVA dispersion of ratio: resin (C) at structure Coating of layer (Z) resin polyester Resin 4 mass %, 20° C. No. liquid (R) (nm) (C) resin (La) (C)/resin(L) (mPa .Math. s) Ex. 1-1 1-1-2 R-1 10 60-98 Elitel 20/80 60 KA5071S Ex. 1-2 1-2-2 R-2 10  5-98 Elitel 20/80 5 KA5071S Ex. 1-3 1-3-2 R-3 10  5-82 Elitel 20/80 5 KA5071S Ex. 1-4 1-4-2 R-4 10 48-80 Elitel 20/80 48 KA5071S Ex. 1-5 1-5-2 R-5 10 60-98 Pesresin 20/80 60 A-684G Ex. 1-6 1-6-2 R-6 10  5-98 Pesresin 20/80 5 A-684G Ex. 1-7 1-7-2 R-7 10  5-82 Pesresin 20/80 5 A-684G Ex. 1-8 1-8-2 R-8 10 48-80 Pesresin 20/80 48 A-684G Ex. 1-9 1-9-2 R-8 5 48-80 Pesresin 20/80 48 A-684G Ex. 1-10 1-10-2 R-8 50 48-80 Pesresin 20/80 48 A-684G Ex. 1-11 1-11-2 R-8 100 48-80 Pesresin 20/80 48 A-684G Ex. 1-12 1-12-2 R-4 5 48-80 Elitel 20/80 48 KA5071S Ex. 1-13 1-13-2 R-4 50 48-80 Elitel 20/80 48 KA5071S Ex. 1-14 1-14-2 R-4 100 48-80 Elitel 20/80 48 KA5071S Ex. 1-15 1-15-2 R-4 10 48-80 Elitel  3/97 48 KA5071S Ex. 1-16 1-16-2 R-4 10 48-80 Elitel 45/55 48 KA5071S Com. Ex. C1-1-2 — — — — — — 1-1 Com. Ex. C1-2-2 CR-1 10 — Elitel — — 1-2 KA5071S Com. Ex. C1-3-2 CR-2 10 — Pesresin — — 1-3 A-684G Com. Ex. C1-4-2 CR-3 10 60-98 — — 60 1-4 Com. Ex. C1-5-2 CR-4 10  5-98 — — 5 1-5 Com. Ex. C1-6-2 CR-5 10  5-82 — — 5 1-6 Com. Ex. C1-7-2 CR-6 10 48-80 — — 48 1-7 Com. Ex. C1-8-2 R-4 10 48-80 Elitel 20/80 48 1-8 KA5071S Appearance Oxygen Layer (Y) after Peel strength after retorting transmission rate Coating retorting Wet .sup.1) Wetted .sup.2) after retorting liquid (S) under stress (gf/15 mm) (gf/15 mm) (cc/m.sup.2 .Math. day .Math. atm) Ex. 1-1 S-1 A 500 290 0.1 Ex. 1-2 S-1 A 490 270 0.2 Ex. 1-3 S-1 A 500 280 0.2 Ex. 1-4 S-1 A 520 300 0.1 Ex. 1-5 S-1 A 510 290 0.2 Ex. 1-6 S-1 A 500 280 0.2 Ex. 1-7 S-1 A 490 290 0.2 Ex. 1-8 S-1 A 520 300 0.1 Ex. 1-9 S-1 A 520 300 0.1 Ex. 1-10 S-1 A 500 270 0.2 Ex. 1-11 S-1 B 490 250 0.3 Ex. 1-12 S-1 A 520 300 0.1 Ex. 1-13 S-1 A 500 270 0.2 Ex. 1-14 S-1 A 480 240 0.3 Ex. 1-15 S-1 B 490 270 0.6 Ex. 1-16 S-1 A 420 190 0.2 Com. Ex. S-1 C 530 260 0.2 1-1 Com. Ex. S-1 C 480 270 6.1 1-2 Com. Ex. S-1 C 470 270 5.7 1-3 Com. Ex. S-1 A 230 <10 0.3 1-4 Com. Ex. S-1 A 210 <10 0.4 1-5 Com. Ex. S-1 A 230 <10 0.5 1-6 Com. Ex. S-1 A 240 <10 0.3 1-7 Com. Ex. — A 470 <10 6.0 1-8 (Aluminum deposited layer) .sup.1) Peel strength between layers measured soon after wiping off surface water immediately following retorting .sup.2) Peel strength between base (X) and layer (Y) measured while dropping ion-exchange water on delaminating interface with a dropper

Example 2: Vertical Form-Fill-Seal Bag

Example 2-1

[0336] An adhesive layer was formed on the multilayer structure (1-1-1) produced in Example 1-1, and an ONY 15 was laminated on the adhesive layer to form a laminate. After forming another adhesive layer on the ONY of the laminate, a CPP 70 was laminated on the adhesive layer, and the laminate was left to stand at 40° C. for 5 days for aging. This produced a multilayer structure (2-1-1). Each of the two adhesive layers was formed by applying the two-component adhesive with a bar coater in a thickness that becomes 3 μm after drying, and drying the adhesive. After cutting the multilayer structure (2-1-1) into sheets of 400 mm width, the sheets were fed to a vertical form-fill-seal packaging machine (manufactured by ORIHIRO Co., Ltd.), and heat sealed on the CPP layers contacting each other. The vertical form-fill-seal packaging machine produced a fin-sealed vertical form-fill-seal bag (2-1-2) (width 160 mm, length 470 mm). The vertical form-fill-seal bag (2-1-2) was heat sealed to form a pouch, and 300 mL of water was filled into the pouch. A retort test conducted for the pouch under the following conditions showed that the pouch retained a good appearance with no breakage or delamination.

Retort Test

[0337] Retorting apparatus: Flavor Ace RSC-60, manufactured by HISAKA WORKS, LTD.

[0338] Temperature: 125° C.

[0339] Time: 30 minutes

[0340] Pressure: 0.17 MPaG

Example 3: Flat Pouch

Example 3-1

[0341] The multilayer structure (2-1-1) produced in Example 2-1 was cut into two 120 mm×120 mm sheets, and the two sheets of multilayer structure were overlaid in such an orientation that the CPP layers were on the inner side. The resulting rectangular laminate was heat sealed on three sides to form a flat pouch (3-1-1). The flat pouch was then filled with 100 mL of water. A retort test conducted for the flat pouch under the same conditions used in Example 2-1 showed that the pouch retained a good appearance with no breakage or delamination.

Example 4: Infusion Bag

Example 4-1

[0342] Two 120 mm×100 mm sheets of multilayer structure were cut out from the multilayer structure (2-1-1) produced in Example 2-1. The two sheets of multilayer structure were then overlaid in such an orientation that the CPP layers were on the inner side. The periphery of the resulting laminate was heat sealed, and a spout (plug member) made of polypropylene was attached by heat sealing. This produced an infusion bag (4-1-1). After filling 100 mL of water into the infusion bag (4-1-1), a retort test was conducted under the same conditions used in Example 2-1. The infusion bag retained a good appearance with no breakage or delamination.

Example 5: Container Lid

Example 5-1

[0343] A 100 mm-diameter circular piece of multilayer structure was cut out from the multilayer structure (2-1-1) produced in Example 2-1, and was used as a container lid. Separately, a flanged container (Hi-Retoflex® HR78-84 manufactured by Toyo Seikan Co., Ltd. under this trade name) was prepared for use as a container body. This product is a cup-shaped container measuring 30 mm in height and 78 mm in diameter at the top. The container has an open top, and the flange portion formed along the periphery of the open top is 6.5 mm wide. The container is configured as a three-layer laminate of olefin layer/steel layer/olefin layer. The container was filled almost full with water, and the lid was heat sealed to the flange portion to obtain a lidded container (5-1-1). For heat sealing, the lid was disposed in such an orientation that the CPP layer of the lid was in contact with the flange portion. A retort test conducted for the lidded container (5-1-1) under the same conditions used in Example 2-1 showed that the lidded container retained a good appearance with no breakage or delamination.

Example 6: In-Mold Labeled Container

Example 6-1

[0344] A two-component adhesive was applied to two sheets of CPP 100 with a bar coater in a thickness that becomes 3 μm after drying on each sheet, and the adhesive was dried. Here, the two-component adhesive is a two-component reactive polyurethane adhesive composed of TAKELAC® A-5255 and TAKENATE® A-50 (both manufactured by Mitsui Chemicals, Inc.). The two CPP sheets were laminated with the multilayer structure (1-1-1) of Example 1-1, and the resulting laminate was allowed to stand at 40° C. for 5 days for aging. This produced a multilayer label (6-1-1) having a configuration of CPP/adhesive layer (I)/base (X-1)/layer (Z-1)/layer (Y-1)/adhesive layer (I)/CPR

[0345] The multilayer label (6-1-1) was cut to conform to the shape of the inner wall surface of a female mold member of a mold for forming a container, and attached to the inner wall surface of the female mold member. After pressing a male mold member into the female mold member, molten polypropylene (NOVATEC® EA7A manufactured by Japan Polypropylene Corporation) was injected into the cavity between the male mold member and female mold member at 220° C. The injection molding produced a container (6-1-2) as intended. The container body had a thickness of 700 μm and a surface area of 83 cm.sup.2. The entire exterior of the container was covered with the multilayer label (6-1-1) overlying the seams, leaving no exterior area that was not covered by the multilayer label (6-1-1). The container (6-1-2) had a good appearance.

Example 7: Extrusion Coating Lamination

Example 7-1

[0346] An adhesive layer was formed on the layer (Y) of the multilayer structure (1-1-1) of Example 1-1, and a polyethylene resin (having a density of 0.917 g/cm.sup.3 and a melt flow rate of 8 g/10 min) was applied on the adhesive layer by extrusion coating lamination at 295° C. to form a layer having a thickness of 20 μm. This produced a laminate (7-1-1) having a configuration of base (X-1)/layer (Z-1)/layer (Y-1)/adhesive layer (I)/polyethylene layer. The adhesive layer (I) was formed by applying a two-component adhesive with a bar coater in a thickness that becomes 0.3 μm after drying, and drying the adhesive. Here, the two-component adhesive is a two-component reactive polyurethane adhesive composed of TAKE LAC® A-3210 and TAKENATE® A-3070 (both manufactured by Mitsui Chemicals, Inc.). A retort test conducted for the laminate (7-1-1) under the same conditions used in Example 2-1 showed that the laminate retained a good appearance with no delamination.

Example 8: Influence of Packaged Material

Example 8-1

[0347] The flat pouch (3-1-1) produced in Example 3-1 was filled with 500 mL of a 1.5% aqueous solution of ethanol, and was subjected to a retort test under the same conditions used in Example 2-1. The pouch retained a good appearance with no delamination.

Examples 8-2 to 8-9

[0348] A retort test was conducted in the same manner as in Example 8-1, except that 500 mL of various materials was filled into the flat pouch(3-1-1), instead of 500 mL of a 1.5% aqueous solution of ethanol. After testing, a measurement sample was cut out from the flat pouch, and the oxygen transmission rate of the sample was measured. The packaged materials are a 1.0% aqueous solution of ethanol (Example 8-2), vinegar (Example 8-3), an aqueous solution of citric acid with a pH of 2 (Example 8-4), an edible oil (Example 8-5), ketchup (Example 8-6), soy sauce (Example 8-7), and a ginger paste (Example 8-8). All of these samples had an oxygen transmission rate of 0.2 cc/(m.sup.2.Math.day.Math.atm) after the retort test. In another retort test conducted in the same manner as in Example 8-1, the lidded container (5-1-1) produced in Example 5-1 was tested with mandarin syrup filling the container almost completely (Example 8-9). The tested lidded container retained a good appearance with no delamination.

[0349] As clearly demonstrated in Examples 8-1 to 8-9, the packaging materials of the present invention retained a good appearance even after the retort tests conducted with various food products.

Example 9: Vacuum Insulator

Example 9-1

[0350] The two-component adhesive used in Example 6-1 was applied on a CPP 50 in a thickness that becomes 3 μm after drying, and the adhesive was dried to form an adhesive layer. The CPP 50 was then bonded to the PET layer of the multilayer structure (2-1-1) produced in Example 2-1. This produced a laminate (9-1-1) having a configuration of CPP/adhesive layer (I)/base (X-1)/layer (Z-1)/layer (Y-1)/adhesive layer (I)/ONY/adhesive layer (I)/CPR Separately, the same two-component reactive polyurethane adhesive was applied on an ONY15 have a thickness of 3 μm after drying, and the adhesive was dried to form an adhesive layer. The ONY 15 was then bonded to the laminate (9-1-1) to obtain a multilayer structure (9-1-2) having a configuration of CPP/adhesive layer (I)/laminate (9-1-1)/adhesive layer (I)/ONY.

[0351] The multilayer structure (9-1-2) was cut into two laminates, each measuring 700 mm×300 mm in size. The laminates were overlaid in such an orientation that the CPP layers were on the inner side. These were then heat sealed on three sides with a seal width of 10 mm. This produced a bag sealed on three sides. Thereafter, a heat-insulating core material was filled into the bag through its opening, and the bag was hermetically closed with a vacuum packaging machine at 20° C. with an internal pressure of 10 Pa. This produced a vacuum insulator (9-1-3). A fine silica powder was used as the heat-insulating core material. The vacuum insulator (9-1-3) was left at 40° C., 15% RH for 360 days, and the internal pressure of the vacuum insulator was measured using a Pirani gauge. The measured pressure was 37.0 Pa.

Example 9-2

[0352] The two-component adhesive used in Example 6-1 was applied on a CPP 50 in a thickness that becomes 3 μm after drying, and the adhesive was dried to form an adhesive layer. The CPP 50 was then bonded to VM-XL to obtain a laminate (9-2-1) having a configuration of VM-XL/adhesive layer/CPP 50. Separately, the same two-component reactive polyurethane adhesive was applied on the layer (Y-1) of the multilayer structure (1-1-1) of Example 1-1 in a thickness that becomes 3 μm after drying, and the adhesive was dried to form an adhesive layer. The multilayer structure (1-1-1) was then bonded to the laminate (9-2-1) to obtain a multilayer structure (9-2-2) having a configuration of base (X-1)/layer (Z-1)/layer (Y-1)/adhesive layer/VM-XL/adhesive layer/CPP 50. In the same manner, another multilayer structure (1-1-1) was bonded to obtain a multilayer structure (9-2-3) having a configuration of base (X-1)/layer (Z-1)/layer (Y-1)/adhesive layer/base (X-1)/layer (Z-1)/layer (Y-1)/adhesive layer/VM-XL/adhesive layer/CPP 50. The multilayer structure (9-2-3) was cut into two laminates, each measuring 700 mm×300 mm in size. The laminates were overlaid in such an orientation that the CPP layers were on the inner side. These were then heat sealed on three sides with a seal width of 10 mm. This produced a bag sealed on three sides. Thereafter, a heat-insulating core material was filled into the bag through its opening, and the bag was hermetically closed with a vacuum packaging machine at 20° C. with an internal pressure of 10 Pa. This produced a vacuum insulator (9-2-4). A fine silica powder was used as the heat-insulating core material. The vacuum insulator (9-2-4) was left at 40° C., 15% RH for 360 days, and the internal pressure of the vacuum insulator was measured using a Pirani gauge. The measured pressure was 28.0 Pa.

Example 10-1

[0353] An adhesive layer was formed on the multilayer structure (1-1-1) produced in Example 1-1, and an acrylic resin film (thickness: 50 μm) was laminated on the adhesive layer to obtain a laminate. Thereafter, another adhesive layer was formed on the base (X-1) of the multilayer structure (1-1-1) of the laminate, and a PET 50 was laminated on the laminate. This produced a protective sheet (10-1-1) having a configuration of PET/adhesive layer (I)/base (X-1)/layer (Z-1)/layer (Y-1)/adhesive layer (I)/acrylic resin film. Each of the two adhesive layers was formed by applying the two-component adhesive in a thickness that becomes 3 μm after drying, and drying the adhesive. The two-component adhesive is a two-component reactive polyurethane adhesive composed of TAKELAC® A-1102 and TAKENATE® A-3070 (both manufactured by Mitsui Chemicals, Inc.).

[0354] The protective sheet (10-1-1) was subjected to a durability test (damp heat test). In the test, the protective sheet was stored in an 85° C., 85% RH atmosphere under atmospheric pressure for 1,000 hours using a thermo-hygrostat. The protective sheet retained a good appearance with no delamination.