Low-carboxylic-end-group PET exhibits better thermooxidative stability than regular PET polymer.

PET is a kind of semi-crystalline polymer obtained by the reaction of PTA and EG. Since PET Polymer came on the scene, it soon became the most abundant variety of synthetic fibers because of its excellent properties. During production, storage, and application, the polyester material’s performance gradually declines due to the combined effects of internal and external factors. So it is essential to research the aging process of polyester.

The content of the COOH is a quality index of polyester materials. And the international requirement of COOH in PET is less than 30 mol/t. The value directly affects the thermal stability of the polyester chips. At the same time, the acid is an esterification catalyst. That is to say, the carboxylic end group can catalyze the depolymerization of the PET molecular chain. High carboxylic end group PET will accelerate the aging and degradation under the catalysis of end groups during processing, storage, and usage. As a result, their performance will drop sharply. Therefore, low-carboxylic-end-group PET is gaining increasing popularity in the market.

Till now, Hubei Decon has researched two types of low-carboxylic-end-group PET Polymer.
One is a film-grade PET chip, which is widely used in solar module back sheets. Our product helps PV to extend its service life. For more information, please click https://www.polyestermfg.com/film-grade-pet-chip/.
Another is a textile-grade polyester chip, which is applied in spinning monofilament yarn. The polymer is also called hydrolysis-resistant PET. The yarn made from low COOH PET can be used in fishing line and paper machines.
According to requirements from the downstream market, we develop different IV Low carboxylic PET Chips. The specifications are as follows.

IV0.65 + COOH 11

NO. PROPERTY UNIT STANDARD TEST RESULTS
Semi-dull Grade Bright Grade
1 IV dl/g 0.646-0.660 0.65 0.65
2 End Carboxyl mol/t ≤12 10.21 11.01
3 Color Value L ≥ 80.5 84.66 83.29
b 5±1.5 4.24 0.80
4 Irregular Chip w% ≤0.4 0.00 0.00
5 hundred-grain Weight g/100 3±0.5 2.85 2.73
6 Moisture Content w% ≤0.4 0.05 0.04
7 TiO2 Content w% 0.295±0.03 0.28 —
8 DEG Content w% ≤1.25 1.15 1.32
9 Melting Point ℃ 260±2 259.8 259.7
10 Agglomerate Particle pce/mg ≤1 0.00 0.00
11 Powder Content mg/kg ≤100 16.00 8.00

IV0.71 + COOH 9

NO. PROPERTY UNIT STANDARDS TESTING RESULT
Semi-dull Grade Bright Grade
1 INTRINSIC VISCOSITY dl/g 0.720±0.015 0.719 0.712
2 MELTING POINT ℃ 253±2 253 253
3 COOH CONTENT mol/t ≤10 8.0 9.0
4 Color Value b ≤6 4.0 -0.2
L 88.10 88.4
5 MOISTURE CONTENT % ≤0.4 0.01 0.03
6 TIO2 CONTENT % 0.28±0.015 0.281 —
7 DEG CONTENT % ≤1.25 1.16 1.20
8 ASH CONTENT mg/kg ≤0.06 0.02 0.03
9 IRON CONTENT mg/kg ≤2 1 1
10 IRREGULAR CHIP % ≤0.3 0.0 0.0
11 POWDER CONTENT mg/kg ≤50 5 5

IV0.88 + COOH 10

NO. PROPERTY UNIT STANDARDS TESTING RESULT
Semi-dull Grade Bright Grade
1 INTRINSIC VISCOSITY dl/g 0.88±0.010 0.88 0.88
2 MELTING POINT ℃ 260±2 261 261
3 COOH CONTENT mol/t ≤12 10 10
4 Color Value b 5.0±1.5 5.8 1.9
L ≥84 88 87
5 MOISTURE CONTENT % ≤0.4 0.1 0.1
6 TIO2 CONTENT % 0.31±0.03 0.30 —
7 DEG CONTENT % 1.05±0.15 0.93 1.1
8 ASH CONTENT mg/kg ≤0.05 0.01 0.01
9 IRON CONTENT mg/kg ≤2 1 1
10 IRREGULAR CHIP % ≤0.3 0.0 0.0
11 POWDER CONTENT mg/kg ≤100 0.0 0.0