# US 11,078,004 B2 · Multilayer film for reclosable pet packaging

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- Number: US 11,078,004 B2
- Document ID: US11078004B2
- Status: Granted
- Kind: B2
- Application number: 15/745,621
- Filed: 2016-07-12
- Published: 2018-08-02
- Granted: 2021-08-03
- Earliest claimed: 2015-07-17
- Assignees: Bostik SA
- Applicants: Bostik SA
- Inventors: Christophe Robert; Marc Brestaz; Ludovic Sallet; Jeremie Peyras-Carratte
- Web page: https://patentgrep.com/patent/US11078004B2

## CPC

- B65D 77/2096: {Adhesive means}
- B32B 7/12: using interposed adhesives or interposed materials with bonding properties
- B32B 25/14: comprising {synthetic rubber copolymers (B32B25/18 and B32B25/20 take precedence)}
- B32B 27/08: of synthetic resin
- B32B 27/302: {comprising aromatic vinyl (co)polymers, e.g. styrenic (co)polymers}
- B32B 27/36: comprising polyesters
- B65D 43/02: Removable lids or covers (with means for piercing, cutting, or tearing a frangible inner closure B65D51/22)
- B32B 2270/00: Resin or rubber layer containing a blend of at least two different polymers
- B32B 2274/00: Thermoplastic elastomer material
- B32B 2307/31: Heat sealable
- B32B 2435/02: for containers
- B65D 2577/2025: Multi-layered container, e.g. laminated, coated
- 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
- B32B: LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM

## Abstract

A multilayer film: an adhesive layer A: an extrudable hot-melt self-adhesive composition; a complexable thin layer B; and a heat-sealable and cleavable layer C of a linear copolyester C1 obtained by polycondensation of a composition of monomers: at least one diol (i), at least one compound (ii) chosen from terephthalic acid or a diester derivative and at least one compound (iii) chosen from an aromatic or aliphatic dicarboxylic acid or a diester or anhydride derivative; the amounts of the monomers (i), (ii) and (iii) used in the polycondensation such that the softening temperature of C1 is below 190° C. A process for producing the multilayer film by co-extrusion blow-molding. A resealable packaging comprising a PET-based receptacle and a seal of said multilayer film, the heat-sealable and cleavable layer (C) of which is heat-sealed on the receptacle.

## Claims

### Claim 1

A multilayer film comprising:
an adhesive layer A having a thickness of 7 to 50 μm and consisting of an extrudable hot-melt self-adhesive composition a which has a melt flow index (or MFI), measured for a temperature of 190° C. and a total weight of 2.16 kg, ranging from 0.01 to 200 g/10 minutes and which comprises, on the basis of the total weight of said composition a:
from 40% to 70% by weight of a composition a1 of styrene block copolymers with at least one elastomer block, said composition a1 consisting of, on the basis of its total weight:
of 30% to 90% by weight of at least one diblock copolymer of styrene-isoprene block copolymer (SI), styrene-butadiene/isoprene block copolymer (SBI), styrene-isoprene/butadiene block copolymer (SIB), styrene-butadiene block copolymer (SB), styrene-ethylene/butylene block copolymer (SEB), styrene-ethylene/propylene block copolymer (SEP), and
of 10% to 70% by weight of at least one triblock copolymer of styrene-isoprene-styrene block copolymer (SIS), styrene-isoprene/butadiene-styrene block copolymer (SIBS), styrene-butadiene-styrene block copolymer (SBS), styrene-ethylene/butylene-styrene block copolymer (SEBS), styrene-ethylene/propylene-styrene block copolymer (SEPS);
the total content of styrene units of said composition a1 being 10% to 40% by weight on the basis of the total weight of a1; and
from 30% to 60% by weight of one or more tackifying resins a2 having a softening temperature of between 5 and 140° C.;
a complexable thin layer B consisting of a thermoplastic b; and
a heat-sealable and cleavable layer C having a thickness of 10 to 150 μm;
the layers B and C being linked to one another by the layer A; and
wherein in said film the layer C consists of a composition c of, on the basis of the total weight of c, a content by weight of at least 95% of at least one linear copolyester C1 obtained by polycondensation of a composition m of monomers of:
at least one diol (i),
at least one compound (ii) that is terephthalic acid or a diester derivative thereof, optionally substituted with an alkyl radical, and
at least one compound (iii) that is an aromatic or aliphatic dicarboxylic acid or a diester or anhydride derivative thereof;
the amounts of the monomers (i), (ii) and (iii) used in the polycondensation being such that the softening temperature of C1 is below 190° C.

### Claim 2 (depends on 1)

The multilayer film as claimed in claim 1, wherein the softening temperature of the linear copolyester C1 included in composition c of the C is below 180° C.

### Claim 3 (depends on 1)

The multilayer film as claimed in claim 1, wherein the linear copolyester C1 is obtained by polycondensation of a composition m consisting of, on the basis of contents expressed as mol % per 100 mol of monomers, of:
approximately 50% of diol (i),
from 10% to 38% of compound (ii), and
from 12% to 40% of compound (iii).

### Claim 4 (depends on 1)

The multilayer film as claimed in claim 1, wherein ethylene glycol is used as diol (i).

### Claim 5 (depends on 1)

The multilayer film as claimed in claim 1, wherein composition a of the layer A has a melt flow index of 2 to 70 g/10 minutes.

### Claim 6 (depends on 1)

The multilayer film as claimed in claim 1, wherein the composition a1 of styrene block copolymers included in the composition a of the layer A consists of an SIS triblock copolymer and an SI diblock copolymer.

### Claim 7 (depends on 1)

The multilayer film as claimed in claim 1, wherein the resin(s) a2 included in the composition a of the layer A are:
(ii) resins obtained by hydrogenation, polymerization or copolymerization with an aromatic hydrocarbon of mixtures of unsaturated aliphatic hydrocarbons having approximately 5, 9 or 10 carbon atoms resulting from petroleum fractions; or
(iii) terpene resins resulting from the polymerization of terpene hydrocarbons in the presence of Friedel-Crafts catalysts, which are optionally modified by the action of phenols.

### Claim 8 (depends on 1)

The multilayer film as claimed in claim 1, wherein composition a of the layer A comprises:
from 50% to 70% of the composition a1 of styrene block copolymers; and
from 30% to 50% of tackifying resin a2.

### Claim 9 (depends on 1)

The multilayer film as claimed in claim 1, wherein the multilayer film also comprises a tie layer D, connecting the layer A to the layer B, and/or a tie layer E, connecting the layer A to the layer C.

### Claim 10 (depends on 1)

The multilayer film as claimed in claim 1, wherein the thickness of the layer A ranges from 8 to 25 μm.

### Claim 11 (depends on 1)

A resealable packaging comprising:
a PET-based receptacle which consists either of amorphous PET or of a bilayer system of amorphous PET and of semicrystalline PET, said receptacle having a flat bottom and a perimeter in the form of a flat band, and
a seal consisting of the multilayer film as defined in claim 1, the layer (C) of which is heat-sealed on the perimeter of the receptacle, in contact with amorphous PET.

### Claim 12 (depends on 1)

A process for producing the multilayer film as defined in claim 1, said process comprising co-extrusion of the composition a, the thermoplastic b and the composition c, at a temperature of between 150° C. and 200° C.

### Claim 13 (depends on 12)

The production process as claimed in claim 12, wherein the co-extrusion is carried out by blow-molding.

### Claim 14 (depends on 12)

The production process as claimed in claim 12, comprising:
(i) the introduction, into separate extruders, of constituent compositions and materials of the layers A, B, C, and optionally a tie layer D and a tie layer E, in the form of granules having a size of between 1 and 10 mm, then
(ii) the conversion by heating of said granules to a viscous liquid state forming viscous compositions, then
(iii) the passing of the viscous compositions through an extrusion head comprising a set of coplanar and concentric annular dies, each brought to a temperature of between 150° C. and 200° C., so as to form a tubular bubble comprising several layers, in which the order of the layers corresponds to that desired for the final film, then
(iv) radial expansion and the drawing of the bubble, then
(v) cooling of said bubble.

### Claim 15 (depends on 14)

The production process as claimed in claim 14, wherein the extrusion head used in step (iii) is a monoblock extrusion head, in which the annular dies are brought to one and the same temperature of between 150° C. and 200° C.