Description

High Modulus Low Shrinkage (HMLS) polyester chip is a modified polymer with higher modulus and lower shrinkage than the regular PET. It is primarily used to produce HMLS industrial yarn and tire cord fabric. According to customers’ requirements, we can supply pre-crystallized high IV and low carboxyl (COOH Value) HMLS PET Chips.

Compared to regular types, high-modulus low-shrinkage (HMLS) polyester chips have the following features.
✅ Higher molecular weight & crystallinity
✅ Superior strength and stability
✅ Minimal shrinkage and deformation during use

High-Modulus Low-Shrinkage Polyester Industrial Yarn (HMLS) exhibits exceptional comprehensive properties, including:

  • Minimal elongation deformation

  • Superior dimensional stability

  • High modulus

  • Low thermal shrinkage

  • Reduced hysteresis loss

These characteristics deliver critical performance advantages:
✅ Reduces rolling resistance in tire manufacturing
✅ Enhances heat/pressure resistance in rubber products

Consequently, HMLS yarn is increasingly replacing standard polyester industrial yarn in Tire reinforcement and Industrial rubber applications.

Production Process

1. Raw Material Selection

Primary raw materials: Purified terephthalic acid (PTA) + Ethylene glycol (EG) + Catalysts and stabilizers

2. Polymerization

Two-stage reaction:
① Esterification:
Raw materials → Monomers
② Polycondensation:
Catalyst-driven reaction → Polyester melt → Pelletized into chips

3. Solid-State Polymerization (SSP)

Chip treatment sequence:
① Leaching & Washing:
Removing impurities/oligomers (hot water/solvent treatment)
② Viscosity Enhancement:
SSP increases intrinsic viscosity (IV) and decreases carboxyl (COOH).

 

Applications

Industry Key Uses Benefits
Automotive Tire cords, seat belts, airbags Enhances strength & safety
Aerospace Structural parts, interior materials Lightweight + high stability
Electronics Wire insulation, component encapsulation Improves heat resistance & dimensional stability
Industrial Filters, conveyor belts, ropes Provides high-strength performance

Parameters

Items Units Standards Test Results
Intrinsic Viscosity
(60:40, phenol: TCE@25℃)		 dl/g 0.88±0.005 0.88
Carboxy End Groups mol/t 12.0±2.0 12
Color Value L ≥82 89.3
b 1.0±1.0 1.4
Melting Point ℃ 261±2.0 261.5
DEG Content % 0.92±0.05 0.94
Moisture Content % ≤0.08 0.01
Ash Content mg/kg ≤500 205
Iron Content mg/kg ≤1.5 0.5
Irregular Chip % ≤0.3 0
Powder Content mg/kg ≤80 0
Granule Weight g/100pcs 1.9±0.10 1.91