Continuous process for preparing a polyester shrinkable film

Patent metadata

Field	Value
Publication number	US-10487184-B2
Application number	US-201715724872-A
Country	US
Kind code	B2
Filing date	Oct 4, 2017
Priority date	Jun 6, 2017
Publication date	Nov 26, 2019
Grant date	Nov 26, 2019

Abstract

A continuous process for preparing a polyester shrinkable film includes: pumping an amorphous PET-based polyester melt having a melt viscosity η1 directly from a polymerization reactor into a first cooling zone; cooling the polyester melt to increase the melt viscosity thereof to a melt viscosity η2 such that a difference between η2 and η1 ranges from 1500 poise to 3500 poise; feeding the polyester melt into a second cooling zone; cooling the polyester melt to increase the melt viscosity thereof to a melt viscosity η3 ranging from 5000 poise to 12000 poise such that a difference between η3 and η2 ranges from 1000 poise to 5500 poise; and pumping the polyester melt from the second cooling zone into a zone for film-forming treatment.

First claim

What is claimed is:

1. A continuous process for preparing a polyester shrinkable film, comprising:
(a) pumping an amorphous PET-based polyester melt having a melt viscosity η1 directly from a polymerization reactor into a first cooling zone in such a manner that a flow rate of the amorphous PET-based polyester melt at an entry of the first cooling zone is substantially the same as the flow rate of the amorphous PET-based polyester melt at an exit of the first cooling zone;
(b) cooling the amorphous PET-based polyester melt in the first cooling zone to increase the melt viscosity of the amorphous PET-based polyester melt to a melt viscosity η2 such that a melt viscosity difference between η2 and η1 ranges from 1500 poise to 3500 poise;
(c) feeding immediately after (b) the amorphous PET-based polyester melt from the first cooling zone into a second cooling zone in such a manner that the flow rate of the amorphous PET-based polyester melt at an entry of the second cooling zone is substantially the same as the flow rate of the amorphous PET-based polyester melt at an exit of the second cooling zone;
(d) cooling the amorphous PET-based polyester melt in the second cooling zone to increase the melt viscosity of the amorphous PET-based polyester melt to a melt viscosity η3 ranging from 5000 poise to 12000 poise such that a melt viscosity difference between η3 and η2 ranges from 1000 poise to 5500 poise; and
(e) pumping the amorphous PET-based polyester melt from the second cooling zone into a zone for film-forming treatment.

2. The continuous process for preparing a polyester shrinkable film according to claim 1 , wherein the amorphous PET-based polyester melt has a pressure P1 at the entry of the first cooling zone, a pressure P2 at the entry of the second cooling zone, and a pressure P3 at the exit of the second cooling zone, wherein P1 is larger than P2, P2 is larger than P3, a pressure difference between P1 and P2 is not larger than 15 bar, and a pressure difference between P2 and P3 is not larger than 15 bar.

3. The continuous process for preparing a polyester shrinkable film according to claim 1 , wherein in (a), the amorphous PET-based polyester melt has a temperature T1, and in (b), the amorphous PET-based polyester melt is cooled to a temperature T2 such that a temperature difference between T2 and T1 ranges from 10° C. to 30° C.

4. The continuous process for preparing a polyester shrinkable film according to claim 3 , wherein in (d), the amorphous PET-based polyester melt is cooled to a temperature T3 such that a temperature difference between T3 and T2 ranges from 10° C. to 30° C.

5. The continuous process for preparing a polyester shrinkable film according to claim 1 , wherein each of the first and second cooling zones includes at least one sub-cooling zone.

6. The continuous process for preparing a polyester shrinkable film according to claim 1 , wherein the amorphous PET-based polyester melt is obtained by subjecting to polymerization a composition which includes a dicarboxylic acid component, a diol component, and a copolymerizable component that provides the amorphous PET-based polyester melt with an improved amorphous property and that is other than the dicarboxylic acid component and the diol component.

7. The continuous process for preparing a polyester shrinkable film according to claim 6 , wherein the copolymerizable component is selected from the group consisting of isophthalic acid, neopentyl glycol, 1,4-cyclohexanedimethanol, 2-methyl-1,3-propylene glycol, diethylated 2-methyl-1,3-propylene glycol, and combinations thereof.

8. The continuous process for preparing a polyester shrinkable film according to claim 7 , wherein the copolymerizable component is isophthalic acid, which is in an amount ranging from 10 to 35 moles based on 100 moles of the dicarboxylic acid component.

9. The continuous process for preparing a polyester shrinkable film according to claim 7 , wherein the copolymerizable component is selected from the group consisting of neopentyl glycol, 1,4-cyclohexanedimethanol, 2-methyl-1,3-propylene glycol, diethylated 2-methyl-1,3-propylene glycol, and combinations thereof, and the copolymerizable component is in an amount ranging from 10 to 25 moles based on 100 moles of the diol component.

10. The continuous process for preparing a polyester shrinkable film according to claim 1 , wherein the amorphous PET-based polyester melt has an intrinsic viscosity larger than 0.58.

11. The continuous process for preparing a polyester shrinkable film according to claim 1 , wherein the film-forming treatment includes casting and biaxial stretching.

Assignees

• Far Eastern New Century Corp

Inventors

• Tsai Ching-Chun
• Liu Tsung-Hung
• Chang Tsan-Chin
• Lin Chi-Feng
• Shiu Jie
• Wang Chien-Wei
• Chen Chin-Tien

Classifications

• B29K2067/003

  PET, i.e. poylethylene terephthalate · CPC title

• C08J5/18 Primary

  Manufacture of films or sheets · CPC title

• B29C55/12

  biaxial · CPC title

• B29C48/305

  having a wide opening, e.g. for forming sheets · CPC title

• C08G63/88

  Post-polymerisation treatment · CPC title