Recycled bis(4-hydroxybutyl)terephthalate, method for preparing same, and polyester resin using same

Patent metadata

Field	Value
Publication number	US-2025059319-A1
Application number	US-202318724608-A
Country	US
Kind code	A1
Filing date	Nov 22, 2023
Priority date	Nov 23, 2022
Publication date	Feb 20, 2025
Grant date	—

Abstract

A recycled bis(4-hydroxybutyl)terephthalate according to an embodiment has a low residual amount of ethylene glycol derivatives, and thus, can be used as a polymerization raw material for high-crystallinity engineering polyester products or biodegradable polyester. Further the recycled bis(4-hydroxybutyl)terephthalate is easily crushed to produce flakes or powder, and provides excellent quality of, for example, colorand provides excellent quality of, for example, color.

First claim

1 . Recycled bis(4-hydroxybutyl) terephthalate in which the total content of ethylene glycol, diethylene glycol, and their derivatives, as measured by 1H-NMR, is 20% by mole or less based on the total number of moles of the entire glycols and their derivatives, and, when it is prepared into a specimen having a thickness of 6 mm, the color-b value in the Hunter Lab color space is 8 or less.

2 . The recycled bis(4-hydroxybutyl) terephthalate of claim 1 , wherein the recycled bis(4-hydroxybutyl) terephthalate comprises a component obtained by the depolymerization of waste polyester, the total content of ethylene glycol, diethylene glycol, and their derivatives is 15% by mole or less based on the total number of moles of the entire glycols and their derivatives, and the color-b value is 5 or less.

3 . The recycled bis(4-hydroxybutyl) terephthalate of claim 1 , wherein the recycled bis(4-hydroxybutyl) terephthalate is capable of being crushed or pulverized into flakes of 0.2 g or less at room temperature.

4 . A process for preparing recycled bis(4-hydroxybutyl) terephthalate, which comprises (1) feeding 1,4-butanediol to a reactor; and (2) feeding bis(2-hydroxyethyl) terephthalate to the reactor in a divided or continuous manner and carrying out a transesterification reaction,
wherein the following Relationship (1) is satisfied:

1
.
5

≤

G
/
B

≤
3.5

(
1
)

in Relationship (1), G is the total number of moles of 1,4-butanediol fed to the reactor, and B is the total number of moles of bis(2-hydroxyethyl) terephthalate fed to the reactor.

5 . The process for preparing recycled bis(4-hydroxybutyl) terephthalate of claim 4 , wherein the purity of the bis(2-hydroxyethyl) terephthalate is 70% to 99%.

6 . The process for preparing recycled bis(4-hydroxybutyl) terephthalate of claim 4 , wherein the bis(2-hydroxyethyl) terephthalate is obtained by the depolymerization of waste polyester.

7 . The process for preparing recycled bis(4-hydroxybutyl) terephthalate of claim 4 , wherein the bis(2-hydroxyethyl) terephthalate is introduced into the transesterification reaction in step (2) in a divided manner of two or more times, and the introduction ratio (R) of bis(2-hydroxyethyl) terephthalate according to the following Relationship (2) is 5 or more:

R
=

G
×

N
B

(
2
)

in Relationship (2), G is the total number of moles of the at least one glycol component, B is the total number of moles of the bis(2-hydroxyethyl) terephthalate, and N is the number of divided introductions of the bis(2-hydroxyethyl) terephthalate.

8 . The process for preparing recycled bis(4-hydroxybutyl) terephthalate of claim 4 , wherein, in step (2), the feeding of bis(2-hydroxyethyl) terephthalate is carried out in a nitrogen atmosphere at a temperature of 165° C. to 220° C. while ethylene glycol as a by-product is removed.

9 . The process for preparing recycled bis(4-hydroxybutyl) terephthalate of claim 4 , wherein, in step (2), the total content of ethylene glycol, diethylene glycol, and their derivatives present in the product of the transesterification reaction is 20% by mole or less based on the total number of moles of the entire glycols and their derivatives.

10 . A raw material for the polymerization of a polyester resin, which comprises the recycled bis(4-hydroxybutyl) terephthalate of claim 1 .

11 . A process for preparing a polyester resin, which comprises:
(1) feeding 1,4-butanediol to a reactor; (2) feeding bis(2-hydroxyethyl) terephthalate to the reactor in a divided or continuous manner and carrying out a transesterification reaction; and (3) subjecting the product of the transesterification reaction to a polycondensation reaction, wherein the following Relationship (1) is satisfied:

1
.
5

≤

G
/
B

≤
3.5

(
1
)

in Relationship (1), G is the total number of moles of 1,4-butanediol fed to the reactor, and B is the total number of moles of bis(2-hydroxyethyl) terephthalate fed to the reactor.

12 . The process for preparing a polyester resin of claim 11 , wherein at least one of glycol components and acid components is further fed in step (3),
the glycol component is selected from the group consisting of 1,3-propanediol, 1,4-cyclohexanedimethanol, 2-methyl-1,3-propanediol, 2-methylene-1,3-propanediol, 2-ethyl-1,3-propanediol, 2-isopropyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol, 2,3-butanediol, 3-methyl-1,5-pentanediol, 3-methyl-2,4-pentanediol, 1,6-hexanediol, 1,2-cyclohexanediol, 1,4-cyclohexanediol, diethylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polyhexamethylene glycol, copolymers of ethylene oxide and tetrahydrofuran, ethylene oxide-adducted polypropylene glycol, polycarbonate diol, polyneopentyl glycol, poly-3-methylpentanediol, and poly-1,5-pentanediol; and the acid component is selected from the group consisting of adipic acid, sebacic acid, succinic acid, isodecylsuccinic acid, maleic acid, fumaric acid, glutaric acid, azelaic acid, 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, diphenyldicarboxylic acid, 4,4′-stilbendicarboxylic acid, 2,5-furandicarboxylic acid, and 2,5-thiophenedicarboxylic acid.

13 . A polyester resin, which is prepared by the process according to claim 11 .

14 . The polyester resin of claim 13 , which has a total content of ethylene glycol residues and diethylene glycol residues of 0.01% by mole to 20% by mole based on the number of moles of the entire glycol residues when measured by 1H-NMR.

15 . The polyester resin of claim 13 , wherein the polyester resin has a melting point (Tm) of 200° C. or higher, a heat of fusion (ΔH f ) of 20 J/g or more, and a color-b value of 18 or less in the Hunter Lab color space when prepared into a specimen having a thickness of 6

Assignees

• Sk Chemicals Co Ltd

Inventors

• Yoo Young-Man
• Hwang Eun-Yeong

Classifications

• C08J2367/02

  Polyesters derived from dicarboxylic acids and dihydroxy compounds; (C08J2367/06 takes precedence) · CPC title

• C08J11/105

  by treatment with enzymes · CPC title

• C08J3/122

  Pulverisation by spraying · CPC title

• C08G63/78

  Preparation processes · CPC title

• C08G63/183 Primary

  Terephthalic acids · CPC title