Post-treatment method of vinyl chloride-based polymer and closed post-treatment system for the same

Patent metadata

Field	Value
Publication number	US-12037442-B2
Application number	US-202017264750-A
Country	US
Kind code	B2
Filing date	Jun 22, 2020
Priority date	Jul 26, 2019
Publication date	Jul 16, 2024
Grant date	Jul 16, 2024

Abstract

The present invention provides a post-treatment method of a vinyl chloride-based polymer including: (a) preparing a stream containing vinyl chloride-based polymer powder and unreacted vinyl chloride-based monomers by drying a vinyl chloride-based polymer latex in a drying unit; (b) filtering the stream containing the vinyl chloride-based polymer powder and the unreacted vinyl chloride-based monomers in a filtering unit; and (c) recirculating a gas containing the unreacted vinyl chloride-based monomers discharged from the filtering unit to a latex storage unit.

First claim

The invention claimed is:

1. A post-treatment method of a vinyl chloride-based polymer comprising:
(a) polymerizing a vinyl chloride-based monomer to prepare a vinyl chloride-based polymer latex;
(b) preparing a stream containing vinyl chloride-based polymer powder and unreacted vinyl chloride-based monomers by drying the vinyl chloride-based polymer latex in a drying unit;
(c) filtering the stream containing the vinyl chloride-based polymer powder and the unreacted vinyl chloride-based monomers in a filtering unit; and
(d) recirculating a gas containing the unreacted vinyl chloride-based monomers discharged from the filtering unit to a latex storage unit; and
(e) adding water to the latex storage unit to separate the unreacted vinyl chloride-based monomers;
wherein a latex stripping process is not performed before the drying step (b) and after the step (a) of polymerizing the vinyl chloride-based monomer to prepare the vinyl chloride-based polymer latex.

2. The post-treatment method of claim 1 , further comprising transferring a stream containing a vinyl chloride-based polymer latex from the latex storage unit to the drying unit before the drying step (b).

3. The post-treatment method of claim 1 , wherein in the filtering step (c), a vinyl chloride-based polymer powder filtered by the filtering unit is obtained.

4. The post-treatment method of claim 1 , further comprising (d′) recirculating the gas containing the unreacted vinyl chloride-based monomers discharged from the drying unit to the latex storage unit.

5. The post-treatment method of claim 1 , wherein the drying step (b) is carried out through spray drying under at an inlet temperature of 100° C. to 250° C.

6. The post-treatment method of claim 1 , wherein the vinyl chloride-based polymer powder in the step (b) has an average particle diameter of 10 μm to 200 μm.

7. A closed post-treatment system for performing the post-treatment method of claim 1 , the system comprising:
a latex storage unit;
a drying unit;
a filtering unit; and
a first reflux line installed between the filtering unit and the latex storage unit to transfer a gas containing unreacted vinyl chloride-based monomers discharged from the filtering unit to the latex storage unit.

8. The closed post-treatment system of claim 7 , further comprising a latex storage unit rear-stage line installed to transfer a stream containing a vinyl chloride-based polymer latex from the latex storage unit to the drying unit.

9. The closed post-treatment system of claim 7 , further comprising:
a second reflux line installed between the drying unit and the latex storage unit to transfer the gas containing the unreacted vinyl chloride-based monomers discharged from the drying unit to the latex storage unit; and
a drying unit rear-stage line installed to transfer a stream containing vinyl chloride polymer powder and unreacted vinyl chloride monomers from the drying unit to the filtering unit.

10. The closed post-treatment system of claim 7 , further comprising a filtering unit rear-stage line for discharging the vinyl chloride-based polymer powder filtered by the filtering unit.

Assignees

• Lg Chemical Ltd

Inventors

• Bae Heung Kwon
• Lee Hyun Min
• Youk Kyung Seog
• Lim Joong Chul
• Lee Se Woong
• Lee Jung Rae

Classifications

• C08F14/06

  Vinyl chloride · CPC title

• C08F6/008

  Treatment of solid polymer wetted by water or organic solvents, e.g. coagulum, filter cakes · CPC title

• C08F6/003 Primary

  from polymer solutions, suspensions, dispersions or emulsions without recovery of the polymer therefrom · CPC title

• C08F2/01

  characterised by special features of the polymerisation apparatus used · CPC title

• C08J3/122 Primary

  Pulverisation by spraying · CPC title