# US 12,180,331 B2 · Recyclable PET film

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- Number: US 12,180,331 B2
- Document ID: US12180331B2
- Status: Granted
- Kind: B2
- Application number: 17/991,052
- Filed: 2022-11-21
- Published: 2023-05-25
- Granted: 2024-12-31
- Earliest claimed: 2021-11-22
- Assignees: Mitsubishi Polyester Film GmbH
- Applicants: Mitsubishi Polyester Film GmbH
- Inventors: Alper Ünal; Thiemo Herbst
- Web page: https://patentgrep.com/patent/US12180331B2

## CPC

- C08G 63/183: Terephthalic acids
- B29B 17/02: Separating plastics from other materials
- B29B 17/0412: {to large particles, e.g. beads, granules, flakes, slices}
- B29C 48/0011: {combined with compression moulding}
- B29C 48/0018: {combined with shaping by orienting, stretching or shrinking, e.g. film blowing (B29C48/0017 takes precedence)}
- B29C 48/08: flexible, e.g. films
- B29C 48/21: the layers being joined at their surfaces
- B29C 48/914: {Cooling drums}
- B32B 7/12: using interposed adhesives or interposed materials with bonding properties
- B32B 27/08: of synthetic resin
- B32B 27/16: specially treated, e.g. irradiated
- B32B 27/18: characterised by the use of special additives
- B32B 27/36: comprising polyesters
- C08G 63/16: Dicarboxylic acids and dihydroxy compounds
- C08J 7/0427: {with only one layer of a composition containing a polymer binder (with more layers C08J7/042)}
- C08J 7/043: Improving the adhesiveness of the coatings per se, e.g. forming primers (adhesives in the form of films or foils characterised by the primer layers between the polymer carriers and the adhesives C09J7/50)
- C08J 11/14: by treatment with steam or water
- C09D 167/02: Polyesters derived from dicarboxylic acids and dihydroxy compounds (C09D167/06 takes precedence)
- B29B 2017/0203: {Separating plastics from plastics}
- B29B 2017/0296: {Dissolving the materials in aqueous alkaline solutions, e.g. NaOH or KOH}
- B29K 2067/00: Use of polyesters {or derivatives thereof}, as moulding material
- B29K 2067/003: {PET, i.e. poylethylene terephthalate}
- B29L 2007/00: Flat articles, e.g. films or sheets (B29L2024/00 takes precedence)
- B29L 2007/008: {Wide strips, e.g. films, webs}
- B29L 2009/00: Layered products
- B32B 2250/02: 2 layers
- B32B 2250/03: 3 layers
- B32B 2250/04: 4 layers
- B32B 2250/24: All layers being polymeric
- B32B 2250/244: All polymers belonging to those covered by group B32B27/36
- B32B 2250/40: Symmetrical or sandwich layers, e.g. ABA, ABCBA, ABCCBA
- B32B 2255/10: on synthetic resin layer or on natural or synthetic rubber layer
- B32B 2255/24: Organic non-macromolecular coating
- B32B 2255/26: Polymeric coating
- 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 2307/518: bi-axially
- B32B 2519/00: Labels, badges
- C08J 2367/02: Polyesters derived from dicarboxylic acids and dihydroxy compounds; (C08J2367/06 takes precedence)
- C08J 2433/06: of esters containing only carbon, hydrogen, and oxygen, the oxygen atom being present only as part of the carboxyl radical
- C08J 2483/04: Polysiloxanes
- Y02W 30/62: Plastics recycling; Rubber recycling
- C08G: MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- B29B: PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
- B29C: SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING (making preforms B29B11/00; making laminated products by combining previously unconnected layers which become one product whose layers will remain together B32B37/00 - B32B41/00)
- B32B: LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- C08J: WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H (working, e.g. shaping, of plastics B29)
- C09D: COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR (cosmetics A61K; processes for applying liquids or other fluent materials to surfaces, in general, B05D; staining wood B27K5/02; glazes or vitreous enamels C03C; natural resins, French polish, drying-oils, driers, turpentine, per se, C09F; polishing compositions other than French polish, ski waxes C09G; adhesives or use of materials as adhesives C09J; materials for sealing or packing joints or covers C09K3/10; materials for stopping leaks C09K3/12; processes for the electrolytic or electrophoretic production of coatings C25D)
- B29K: INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR {MOULDS, } REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
- B29L: INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES
- Y02W: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT

## Abstract

The present invention relates to a multilayer, coextruded polyester film including at least one outer layer (A) and a base layer (B), in which the at least one outer layer (A) includes, to an extent of at least 60 wt %, a polyester or a copolyester formed from units derived from aliphatic dicarboxylic acids and diols, wherein the units derived from dicarboxylic acids are selected from one or more dicarboxylic acids from the group of succinic acid, adipic acid, suberic acid, azelaic acid and sebacic acid, and the units derived from diols are selected from one or more diols from the group of ethylene glycol, 1,3-propanediol, 1,4-butanediol and neopentyl glycol. The present invention further relates to a process for producing the film according to the invention, to the use thereof and to a process for recycling the polyester film according to the invention.

## Claims

### Claim 1

A process for recycling a polyester film comprising the steps of:
comminuting a multilayer, coextruded polyester film,
contacting the comminuted polyester film with an aqueous alkali metal hydroxide-containing solution to dissolve the at least one outer layer (A),
separating the comminuted polyester film, wherein the comminuted polyester film no longer comprises an outer layer (A), and
drying the comminuted polyester film, wherein the coextruded polyester film comprises at least one outer layer (A) and a base layer (B), and
the at least one outer layer (A) contains at least 60 wt % of a polyester or a copolyester consisting of units derived from aliphatic dicarboxylic acids and diols, wherein the units derived from dicarboxylic acids are selected from one or more dicarboxylic acids from the group consisting of succinic acid, adipic acid, suberic acid, azelaic acid and sebacic acid, and the units derived from diols are selected from one or more diols from the group consisting of ethylene glycol, 1,3-propanediol, 1,4-butanediol and neopentyl glycol.

### Claim 2 (depends on 1)

The process according to claim 1, wherein the aqueous alkali metal hydroxide-containing solution is an NaOH-or KOH-containing solution.

### Claim 3 (depends on 1)

The process according to claim 1, wherein the aqueous alkali metal hydroxide-containing solution is a 1 to 10 wt % aqueous NaOH- or KOH-containing solution and has a temperature of 80° C. to 98° C.

### Claim 4 (depends on 3)

The process according to claim 3, wherein the aqueous alkali metal hydroxide-containing solution has a temperature of 80° C. to 95° C.

### Claim 5 (depends on 1)

The process according to claim 1, wherein the contacting with the aqueous alkali metal hydroxide-containing solution step is performed for a period of 5 to 30 minutes.

### Claim 6 (depends on 1)

The process according to claim 1, wherein the contacting with the aqueous alkali metal hydroxide-containing solution step is performed for a period of 7 to 15 minutes.

### Claim 7 (depends on 1)

A process for producing a polyester film, comprising employing a recycled polyester film obtained by a process according to claim 1 in polyester film production.

### Claim 8 (depends on 1)

The process according to Claim 1, wherein the outer layer (A) contains at most 40 wt % polyethylene terephthalate.

### Claim 9 (depends on 1)

The process according to Claim 1, wherein the outer layer (A) contains at most 20 wt % polyethylene terephthalate.

### Claim 10 (depends on 1)

The process according to claim 1, wherein the polyester film does not contain wax.