# US 8,784,960 B2 · Multilayer structure and method for producing same

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- Number: US 8,784,960 B2
- Document ID: US8784960B2
- Status: Granted
- Kind: B2
- Application number: 13/638,730
- Filed: 2011-03-30
- Published: 2013-01-24
- Granted: 2014-07-22
- Earliest claimed: 2010-03-31
- Assignees: Kuraray Co., Ltd.
- Applicants: Takeyuki Igarashi; Yasuhiko Haneda; Masahiro Kitamura
- Inventors: Takeyuki Igarashi; Yasuhiko Haneda; Masahiro Kitamura
- Web page: https://patentgrep.com/patent/US8784960B2

## CPC

- B32B 27/306: {comprising vinyl acetate or vinyl alcohol (co)polymers}
- B32B 1/00: Layered products having a non-planar shape
- B32B 7/12: using interposed adhesives or interposed materials with bonding properties
- B32B 27/08: of synthetic resin
- B32B 27/28: comprising synthetic resins not wholly covered by any one of the sub-groups {B32B27/30 - B32B27/42}
- B32B 27/32: comprising polyolefins {(comprising vinyl (co)polymers or acrylic (co)polymers B32B27/30)}
- B32B 2270/00: Resin or rubber layer containing a blend of at least two different polymers
- B32B 2272/00: Resin or rubber layer comprising scrap, waste or recycling material
- B32B 2307/308: Heat stability
- B32B 2307/7242: Non-permeable
- B32B 2307/7244: Oxygen barrier
- B32B 2439/70: Food packaging
- B32B 2439/80: Medical packaging
- Y10T 428/1334: Nonself-supporting tubular film or bag [e.g., pouch, envelope, packet, etc.]
- Y10T 428/1352: Polymer or resin containing [i.e., natural or synthetic]
- Y10T 428/1372: Randomly noninterengaged or randomly contacting fibers, filaments, particles, or flakes
- Y10T 428/1379: Contains vapor or gas barrier, polymer derived from vinyl chloride or vinylidene chloride, or polymer containing a vinyl alcohol unit
- Y10T 428/24967: Absolute thicknesses specified
- B32B: LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

A multilayer structure, comprising: a layer of a resin composition (A); a layer of a saponified ethylene-vinyl acetate copolymer (B); and a layer of polyolefin (C) arranged on one side or both sides of those layers, wherein the resin composition (A) contains polyolefin (D), a saponified ethylene-vinyl acetate copolymer (E) and a saponified ethylene-vinyl acetate copolymer (F1) and/or an acid-modified ethylene-vinyl acetate copolymer (F2), the copolymer (E) has a mass ratio [E/(F1+F2)] of from 0.05 to 30, the polyolefin (D) has the copolymer (E) having an average particle diameter of from 0.1 to 1.8 μm dispersed in a matrix thereof, the layers of (A) and of (C) have thicknesses of from 50 to 1000 μm, and from 25 to 1000 μm, respectively, which enables provision of a multilayer structure having good gas barrier properties after retort processing and a good appearance.

## Claims

### Claim 1

A retort processed package, comprising:
a multilayer container and a content in the container,
the multilayer container comprising:
a layer of a resin composition (A);
a layer of a saponified ethylene-vinyl acetate copolymer (B) having an ethylene content of from 20 to 65 mol % and having a degree of saponification of vinyl acetate units of 96% or more; and
a layer of polyolefin (C) on a side of the layer of a resin composition (A) and the layer of a saponified ethylene-vinyl acetate copolymer (B),
wherein
the container comprises two of the layers of the resin composition (A), and the layer of the saponified ethylene-vinyl acetate copolymer (B) is between the layers of the resin composition (A),
the resin composition (A) comprises a polyolefin (D), a saponified ethylene-vinyl acetate copolymer (E) having an ethylene content of from 20 to 65 mol % and having a degree of saponification of vinyl acetate units of 96% or more, and from 0.3 to 2.0 mass % of the resin composition (A) of at least one copolymer (F) selected from the group consisting of a saponified ethylene-vinyl acetate copolymer (F1) having an ethylene content of from 68 to 98 mol % and having a degree of saponification of vinyl acetate units of 20% or more and an acid-modified ethylene-vinyl acetate copolymer (F2) having an ethylene content of from 68 to 98 mol %,
a mass ratio (E/F) of the saponified ethylene-vinyl acetate copolymer (E) to a total of the copolymer (F) is from 0.05 to 30,
the saponified ethylene-vinyl acetate copolymer (E) is dispersed as particles with an average particle diameter of from 0.1 to 1.8 μm in a matrix of the resin composition polyolefin (D),
the layer of the resin composition (A) has a thickness of from 50 to 1000 μm,
the layer of the polyolefin (C) has a thickness of from 25 to 1000 μm, and
the container has an oxygen transmission rate after 24 hours passed since retort processed for 30 minutes at 120° C. and 0.15 MPa of from 0.1 to 6 cc/m2·day·atm.

### Claim 2 (depends on 1)

The retort processed package of claim 1,
wherein the structure comprises two of the layers of polyolefin (C),
the two layers of the resin composition (A) and the layer of the saponified ethylene-vinyl acetate copolymer (B) between said two layers are between the two layers of polyolefin (C),
each of the two layers of the polyolefin (C) have a thickness of from 25 to 1000 μm.

### Claim 3 (depends on 1)

The retort processed package of claim 1,
wherein the resin composition (A) further comprises an unmodified ethylene-vinyl acetate copolymer (G), and
a mass ratio (G/F) of the unmodified ethylene-vinyl acetate copolymer (G) to a total of the copolymer (F) is from 0.1 to 15.

### Claim 4 (depends on 1)

The retort processed package of claim 1, wherein the resin composition (A) comprises from 2 to 20 mass % of the saponified ethylene-vinyl acetate copolymer (E).

### Claim 5 (depends on 1)

The retort processed package of claim 1,
wherein
either the layer of the polyolefin (C) is on a side of the layers of the resin composition (A) and the layer of the saponified ethylene-vinyl acetate copolymer (B), or the layers of the resin composition (A) and the layer of the saponified ethylene-vinyl acetate copolymer (B) are between two layers of the polyolefin (C).

### Claim 6 (depends on 5)

The retort processed package of claim 5, wherein the layers of the resin composition (A) and the layer of the saponified ethylene-vinyl acetate copolymer (B) are between two layers of the polyolefin (C).

### Claim 7 (depends on 1)

The retort processed package of claim 1, wherein the layer of the saponified ethylene-vinyl acetate copolymer (B) has a thickness of from 6 to 12% of a total thickness of the multilayer container.

### Claim 8 (depends on 1)

The retort processed package of claim 1, wherein the multilayer container has a total thickness of from 200 to 10000 μm.

### Claim 9 (depends on 1)

The retort processed package of claim 1, wherein the polyolefin (C) has a melting point of from 120 to 220° C.

### Claim 10 (depends on 1)

A method of producing the retort processed package of claim 1, the method comprising:
melt molding the multilayer container with the resin composition (A), the saponified ethylene-vinyl acetate copolymer (B), and the polyolefin (C),
wherein the resin composition (A) is obtained by a process comprising melt kneading a scrap of a multilayer container, comprising a layer of polyolefin (D) and a layer of the saponified ethylene-vinyl acetate copolymer (E), and the copolymer (F).

### Claim 11 (depends on 10)

The method of claim 10, further comprising:
melt kneading a scrap of a multilayer container, thereby obtaining the resin composition (A) prior to the melt molding,
wherein the multilayer container comprises a layer of the polyolefin (D) and a layer of the saponified ethylene-vinyl acetate copolymer (E).

### Claim 12 (depends on 1)

The retort processed package of claim 1, wherein the polyolefin (D) comprises a polypropylene-based resin, a polyethylene-based resin, or any combination thereof.

### Claim 13 (depends on 12)

The retort processed package of claim 12, wherein the polyolefin (D) comprises polypropylene, a propylene-based copolymer, polyethylene, an ethylene-based copolymer, or any combination thereof.

### Claim 14 (depends on 1)

The retort processed package of claim 1, wherein the ethylene content of the saponified ethylene-vinyl acetate copolymer (E) is from 25 to 55 mol %.

### Claim 15 (depends on 1)

The retort processed package of claim 1, wherein at least copolymer (F1) is present.

### Claim 16 (depends on 1)

The retort processed package of claim 1, wherein at least copolymer (F2) is present.