Low Carboxyl Polyester Chips - China

Factors Affecting Carboxyl End Groups in Textile-Grade Polyester Chips

An important influencing factor in textile-grade polyester chips is the carboxyl end group (-COOH).

These groups form mainly during the esterification and polycondensation stages.

Incomplete esterification reactions can leave carboxyl groups in the final product.

Side reactions such as thermal degradation, thermo-oxidative degradation, and etherification in the polycondensation reaction will also produce carboxyl end groups.

How do we control the carboxyl end group?

1 - Change esterification conditions

The conditions in the esterification tank, including the molar ratio of EG to PTA, esterification temperature, esterification degree, and esterification pressure, directly affect the CEG content in polyester chips.

Here are four factors to consider:

1.1 EG/PTA molar ratio

When the molar ratio increases (i.e. the PTA ratio decreases), the carboxyl content decreases.

This will lead to a decrease in -COOH content in polyester chips.

Conversely, lower molar ratios increase —COOH content.

1.2 Degree of esterification

About 95% of the esterification occurs in the esterification tank.

As the liquid level increases, the material remains in the tank longer.

This results in more complete esterification and lower -COOH content.

Conversely, lower levels increase -COOH content.

1.3 Esterification temperature

Esterification reaction is an endothermic reaction.

Higher temperatures push the reaction forward, reducing the amount of -COOH in the slices.

Lower temperatures have the opposite effect.

1.4 Esterification pressure

Higher pressure will push the reaction forward, thus reducing the -COOH content.

Lower pressure increases it.

2 - Polycondensation reaction

The temperature of the polycondensation reaction also affects the -COOH content.

Lowering the temperature can reduce thermal degradation and thus reduce -COOH content.

These temperatures are especially those of the final polycondensation tank.

However, there are limits to adjusting the temperature.

Because lower temperatures also slow down the primary reaction.

The levels in the precondensation and final polycondensation tanks have little effect on -COOH content.

Since most esterification occurs in the esterification tank.

3 - Production Capacity

When process conditions remain unchanged, reducing production capacity allows longer reaction times.

It can lower -COOH content as they continue to react.

Increasing production capacity has the opposite effect.

So, -COOH content is a key factor in determining the maximum production capacity of polyester equipment.

Conclusion

To ensure high-quality spinning-grade polyester chips, it is essential to control the -COOH content.

This can be achieved by:

Increasing the esterification rate

Adjusting the molar ratio, level, temperature, and pressure in the esterification tank

Lowering the polycondensation reaction temperature

Controlling production capacity

By managing these factors, -COOH content can be effectively reduced.

Thereby ensuring the quality of polyester chips for spinning.

Company Contact:

• Posted By: HanLink Polyester Global Solution Co., Ltd

• Phone: 13349886706

• Address: Guannan 4th Road, Guannan Industrial Park, East Lake High Tech District, Wuhan, Hubei, China 430074, wuhan , 开业 , China

• Email:

• Website: https://globalpolyester.com/

• Business Description: We sell: special polyester chips, flame retardant polyester chips, cationic polyester chips, low melting point polyester chips, alkali soluble polyester chips