Recyclable PET film
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.
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.
2. The process according to claim 1 , wherein the aqueous alkali metal hydroxide-containing solution is an NaOH-or KOH-containing solution.
3. 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.
4. The process according to claim 3 , wherein the aqueous alkali metal hydroxide-containing solution has a temperature of 80° C. to 95° C.
5. 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.
6. 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.
7. 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.
8. The process according to Claim 1 , wherein the outer layer (A) contains at most 40 wt % polyethylene terephthalate.
9. The process according to Claim 1 , wherein the outer layer (A) contains at most 20 wt % polyethylene terephthalate.
10. The process according to claim 1 , wherein the polyester film does not contain wax.