# US 12,600,542 B2 · Multilayer structure and packaging material comprising same

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- Number: US 12,600,542 B2
- Document ID: US12600542B2
- Status: Granted
- Kind: B2
- Application number: 17/276,493
- Filed: 2019-10-03
- Published: 2021-09-02
- Granted: 2026-04-14
- Earliest claimed: 2018-10-04
- Assignees: Kuraray Co., Ltd.
- Applicants: Kuraray Co., Ltd.
- Inventors: Makoto Suzuki
- Web page: https://patentgrep.com/patent/US12600542B2

## CPC

- B32B 27/00: Layered products comprising {a layer of} synthetic resin {(fibrous or filamentary layer made of a synthetic resin B32B5/02; particulate layer made of a synthetic resin B32B5/16; foamed layer made of a synthetic resin B32B5/18)}
- B65D 65/40: Applications of laminates for particular packaging purposes {(B65D1/0215, B65D1/28, B65D3/22, B65D5/0281, B65D5/563, B65D9/30, B65D29/02, B65D31/02, B65D75/26, B65D77/2024, B65D81/1275, B65D81/3811, B65D81/3823, B65D81/3834, B65D81/3846, B65D81/3858, B65D81/3874, B65D81/3886, B65D81/3897 take precedence; laminates per se or laminated packages characterised by the composition or)}
- B32B 7/12: using interposed adhesives or interposed materials with bonding properties
- B32B 25/08: of synthetic resin
- B32B 25/14: comprising {synthetic rubber copolymers (B32B25/18 and B32B25/20 take precedence)}
- B32B 27/08: of synthetic resin
- B32B 27/18: characterised by the use of special additives
- B32B 27/20: using fillers, pigments, thixotroping agents
- B32B 27/288: {comprising polyketones}
- B32B 27/302: {comprising aromatic vinyl (co)polymers, e.g. styrenic (co)polymers}
- B32B 27/304: {comprising vinyl halide (co)polymers, e.g. PVC, PVDC, PVF, PVDF}
- B32B 27/306: {comprising vinyl acetate or vinyl alcohol (co)polymers}
- B32B 27/308: {comprising acrylic (co)polymers}
- B32B 27/32: comprising polyolefins {(comprising vinyl (co)polymers or acrylic (co)polymers B32B27/30)}
- B32B 27/327: {comprising polyolefins obtained by a metallocene or single-site catalyst}
- B32B 27/36: comprising polyesters
- B32B 2250/02: 2 layers
- B32B 2250/03: 3 layers
- B32B 2250/05: 5 or more layers
- B32B 2250/24: All layers being polymeric
- B32B 2250/40: Symmetrical or sandwich layers, e.g. ABA, ABCBA, ABCCBA
- B32B 2307/308: Heat stability
- B32B 2307/50: having particular mechanical properties
- B32B 2307/536: Hardness
- B32B 2307/558: Impact strength, toughness
- B32B 2307/72: Density
- B32B 2307/7242: Non-permeable
- B32B 2307/732: Dimensional properties
- B32B 2307/738: Thermoformability
- B32B 2439/46: Bags
- B32B 2439/70: Food packaging
- B32B 2439/80: Medical packaging
- B32B 2553/00: Packaging equipment or accessories not otherwise provided for
- B32B 2597/00: Tubular articles, e.g. hoses, pipes
- B32B: LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B65D: CONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS, e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES, DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; PACKAGING ELEMENTS; PACKAGES

## Abstract

There is provided a multilayer structure having a hard layer (A) and either a resin composition layer (B1) or a resin composition layer (B2), wherein the hard layer (A) has a puncture strength of 40 N/mm or more and 150 N/mm or less; the resin composition layer (B1) is made of a resin comprising an ethylene-vinyl alcohol copolymer (b1) having a melting point Tm1 of 170° C. or more and an ethylene-vinyl alcohol copolymer (b2) having a melting point Tm2 of less than 170° C.; and the resin composition layer (B2) is made of a resin comprising a modified ethylene-vinyl alcohol copolymer containing a modifying group having a primary hydroxy group represented by formula (I). The multilayer structure is excellent in mechanical strength and thermal formability, and when being recovered, allows for melt kneading with less hard spots due to resin deterioration (gelation), showing excellent recyclability.

## Claims

### Claim 1

A multilayer structure comprising:
a hard layer (A) comprising an olefinic polymer including a linear low-density polyethylene polymer or copolymer, wherein the linear low-density polyethylene polymer or copolymer is made by polymerization using a metallocene catalyst,
either a resin composition layer (B1) or a resin composition layer (B2), and
an adhesive resin layer (C) comprising maleic anhydride-modified polyethylene, wherein
the hard layer (A) has a puncture strength of 45 N/mm or more and 100 N/mm or less;
the resin composition layer (B1) consists of:
an ethylene-vinyl alcohol copolymer (b1) having a melting point Tm1 of 190° C. or more,
an ethylene-vinyl alcohol copolymer (b2) having a melting point Tm2 of less than 170° C., and
at least one optional additive selected from the group consisting of a saturated aliphatic amide; an unsaturated aliphatic acid amide; a bis-aliphatic acid amide; an aliphatic acid metal salt; a polyolefin having a molecular weight of about 500 to 10,000; an inorganic filler; an aliphatic polyol; an inorganic oxygen absorber; ascorbic acid; an aliphatic acid ester of ascorbic acid; a metal salt of ascorbic acid; hydroquinone; gallic acid; a polyhydric phenol; bis-salicyl aldehyde-imine cobalt; tetraethylenepentamine cobalt; a cobalt-Schiff base complex; a porphyrin; a macrocyclic polyamine complex; a polyethyleneimine-cobalt complex; a terpene compound; a reaction product of an amino acid with a hydroxyl-containing reducing substance; a triphenylmethyl compound; an alkali metal salt of acetic acid; an alkali metal salt of propionic acid; an alkali metal salt of lauric acid; an alkali metal salt of stearic acid; an alkali metal salt of oleic acid; an alkali metal salt of behenic acid sulfuric acid; an alkali metal salt of sulfurous acid; an alkali metal salt of carbonic acid; an alkali metal salt of boric acid; an alkali metal salt of phosphoric acid; an alkaline earth metal acetate salt; an alkaline earth metal borate salt; an alkaline earth metal phosphate salt; and an alkaline earth metal hydrogen phosphate salt;
an ethylene content of the ethylene-vinyl alcohol copolymer (b1) is 18 to 35 mol %;
an ethylene content of the ethylene-vinyl alcohol copolymer (b2) is 38 to 45 mol %;
a saponification degree of each of the ethylene-vinyl alcohol copolymer (b1) and the ethylene-vinyl alcohol copolymer (b2) are 99 mol % or more; and
the resin composition layer (B2) is made of a resin comprising a modified ethylene-vinyl alcohol copolymer containing a modifying group having a primary hydroxy group represented by formula (I),
wherein:
X represents a methyl group or a group represented by R2—OH;
R1 and R2 represent independently of each other a single bond, an alkylene group having 1 to 9 carbon atoms or an alkyleneoxy group having 1 to 9 carbon atoms; and
the alkylene group and the alkyleneoxy group optionally contain a hydroxy group, an alkoxy group or a halogen atom.

### Claim 2 (depends on 1)

The multilayer structure according to claim 1, wherein a mass ratio (b2/b1) of the ethylene-vinyl alcohol copolymer (b2) to the ethylene-vinyl alcohol copolymer (b1) is 1/99 to 50/50.

### Claim 3 (depends on 1)

The multilayer structure according to claim 1, wherein an absolute value |b2−b1| of a difference between an ethylene content (mol %) of the ethylene-vinyl alcohol copolymer (b2) and an ethylene content (mol %) of the ethylene-vinyl alcohol copolymer (b1) is 5 or more.

### Claim 4 (depends on 1)

The multilayer structure according to claim 1, wherein the olefinic polymer includes the linear low-density polyethylene polymer.

### Claim 5 (depends on 1)

The multilayer structure according to claim 1, wherein the olefinic polymer includes the linear low-density polyethylene copolymer.

### Claim 6 (depends on 1)

The multilayer structure according to claim 1, wherein the linear low-density polyethylene polymer or copolymer comprises a plant-derived linear low-density polyethylene.

### Claim 7 (depends on 1)

The multilayer structure according to claim 1, wherein the olefinic polymer further comprises an ethylene-unsaturated carboxylic acid copolymer ionomer.

### Claim 8 (depends on 1)

The multilayer structure according to claim 1, wherein a density of the olefinic polymer is 0.940 or less.

### Claim 9 (depends on 1)

The multilayer structure according to claim 1, wherein a melting point of the olefinic polymer is 130° C. or less.

### Claim 10 (depends on 1)

The multilayer structure according to claim 1, wherein a melt flow rate (190° C., 2160 g) of the olefinic polymer is less than 5.0 g/10 min.

### Claim 11 (depends on 1)

The multilayer structure according to claim 1, wherein the resin composition layer (B1) or the resin composition layer (B2) is disposed between two hard layers (A).

### Claim 12 (depends on 1)

The multilayer structure according to claim 1, comprising the adhesive resin layer (C) between the hard layer (A) and either the resin composition layer (B1) or the resin composition layer (B2).

### Claim 13 (depends on 12)

The multilayer structure according to claim 12, having a layer structure of the adhesive resin layer (C)/the resin composition layer (B1) or the resin composition layer (B2)/the adhesive resin layer (C).

### Claim 14 (depends on 12)

The multilayer structure according to claim 12, wherein a mass ratio (b2/b1) of the ethylene-vinyl alcohol copolymer (b2) to the ethylene-vinyl alcohol copolymer (b1) is 5/95 to 40/60.

### Claim 15 (depends on 1)

A packaging material comprising the multilayer structure according to claim 1.

### Claim 16 (depends on 1)

A recovered composition comprising a recovered material of the multilayer structure according to claim 1.

### Claim 17 (depends on 1)

A method for producing a recovered composition, comprising melt kneading a recovered material of the multilayer structure according to claim 1.

### Claim 18 (depends on 1)

The multilayer structure according to claim 1, comprising the resin composition layer (B2), wherein X represents a group represented by R2—OH.