Celanese Zytel 73G15HSL PA6

1. Introduction to Celanese Zytel 73G15HSL PA6

Celanese Zytel 73G15HSL PA6 is a highly engineered polyamide 6 (PA6) resin, part of Celanese's extensive Zytel® portfolio of nylon materials. This material is specifically designed to meet stringent performance requirements across various demanding industries. Its formulation incorporates key enhancements that provide a balance of mechanical, thermal, and electrical properties, making it a versatile choice for applications requiring robust and reliable performance.

1.1 Product Identification and Nomenclature

• Zytel®: Celanese's proprietary brand name for its range of nylon (polyamide) resins. The Zytel® family includes various PA6, PA66, and other polyamide types, known for their strength, toughness, and temperature resistance.
• PA6: Polyamide 6, a widely used engineering thermoplastic synthesized from caprolactam. PA6 is recognized for its excellent balance of properties and cost-effectiveness compared to other polyamides.
• G15: Indicates reinforcement with 15% glass fiber, significantly enhancing mechanical strength, stiffness, and dimensional stability.
• HSL: Signifies "Heat Stabilized" or "Heat Stable," crucial for long-term performance and resistance to thermal degradation in elevated temperature applications.

Specific variants exist, such as Zytel® 73G15HSL ECO-R 311 BLK1 (incorporating 30% post-industrial recycled content) and Zytel® 73G15HSL BK363. The resin identification is PA6-GF15 (with REC30 for ECO-R) according to ISO 1043, and the part marking code is >PA6-GF15< (or >PA6-GF15 (REC30)<) per ISO 11469.

1.2 General Characteristics and Key Features

Zytel® 73G15HSL PA6 offers high mechanical strength, an excellent balance of stiffness and toughness, and robust high-temperature performance. Its heat stabilization ensures long-term reliability under extreme thermal conditions. Additionally, it provides good electrical and flammability properties, excellent abrasion and chemical resistance, and is known for its moldability and colorability, offering design flexibility.

1.3 Sustainability Profile

Celanese is committed to sustainability. Variants like Zytel® 73G15HSL ECO-R 311 BLK1 integrate 30% post-industrial recycled (PIR) content. The inherent melt stability facilitates recycling of production waste, supporting a circular economy. When recycling isn't viable, incineration with energy recovery is recommended, with a significant energy recovery potential of -31 kJ/g of base polymer. The use of nylon/polyamide materials also enables lighter-weight and longer-lasting products.

2. Material Properties

The performance characteristics of Zytel 73G15HSL PA6 are comprehensively defined by its rheological, mechanical, thermal, electrical, and physical properties, typically measured under both dry-as-molded (DAM) and conditioned states.

2.1 Rheological Properties

Rheological properties are crucial for understanding the material's flow behavior during processing, particularly injection molding.

• Molding Shrinkage: Typically 0.4 - 0.8% parallel to flow and 0.8 - 1.2% normal to flow for the ECO-R variant (ISO 294-4, 2577).
• Viscosity Number: 139 cm³/g for Zytel® 73G15L NC010 and 145 cm³/g for Zytel® 73G15HSL BK363 (ISO 307, 1157, 1628), indicating good melt flow.

2.2 Mechanical Properties

The mechanical integrity is a key advantage, significantly affected by conditioning due to moisture absorption.

The data indicates that while dry material offers higher stiffness and strength, the conditioned material significantly improves in ductility and toughness, critical for applications where parts might absorb moisture.

2.3 Thermal Properties

Thermal properties dictate the material's performance across various temperature ranges, from processing to end-use environments.

High melting temperature and deflection temperatures highlight its ability to maintain structural integrity at elevated temperatures. Heat stabilization further enhances long-term performance. Flammability ratings indicate flame resistance, beneficial for electrical and household applications.

2.4 Electrical Properties

Zytel® 73G15HSL BK363 exhibits an electric strength of 21.5 kV/mm in the dry state (IEC 60243-1), crucial for insulating components. Electrical properties can be highly dependent on moisture content, typically decreasing as moisture absorption increases.

2.5 Physical/Other Properties

Water and humidity absorption values are typical for polyamides, influencing mechanical properties and dimensional stability. Density reflects the glass fiber reinforcement.

2.6 Chemical Resistance

Zytel® 73G15HSL PA6 exhibits good chemical resistance to a broad spectrum of substances, making it suitable for applications exposed to various chemical environments. This includes resistance to many acids (with caveats for strong mineral acids), bases, alcohols, hydrocarbons, mineral oils, standard fuels, and salt solutions.

For a detailed list of tested substances, please refer to the comprehensive technical document.

3. Processing Guidelines for Injection Molding

Celanese Zytel 73G15HSL PA6 is designed for injection molding. Adhering to specific guidelines is critical for optimal part quality and performance.

3.1 Preprocessing (Drying)

Polyamide materials are hygroscopic. Excess moisture during processing can lead to degradation and defects.

• Moisture Content: Should be lower than 0.15% for general grades.
• Drying Conditions: Dehumidified air with -20°C dew point. Typically 4-8 hours at 80-90°C for 0.20%-0.40% starting moisture.
• Considerations: Improper storage leads to longer drying times. Excessive drying can increase melt viscosity and cause discoloration.

3.2 Injection Molding Parameters

Recommended parameters for optimal material flow, part integrity, and surface finish:

• Machine Temperatures:
  • Barrel: Optimum melt temperature around 270°C (range 260-280°C).
  • Nozzle/Hot Runners: Up to 300°C.
• Mold Temperatures: Optimum 100°C (range 70-120°C).
• Back Pressure: 5-10 bar (hydraulic), or low/no back pressure for better melt quality.
• Injection Speed: Fast (1-3 seconds) for thin sections and good surface appearance.
• Screw Speed: Adjust so retraction times are shorter than cooling phase; avoid high speeds with glass-reinforced resins. Max 0.2 m/s tangential speed.
• Hold Pressure: 50-100 MPa. Time: 3 seconds per mm wall thickness.
• Residence Time: Optimum 3-5 minutes, max 10 minutes.
• Regrind: Possible, suitability depends on part requirements.
• Additives: Contains release agents and lubricants.

3.3 Post-processing (Conditioning and Annealing)

Post-molding treatments enhance final performance and dimensional stability.

• Moisture Conditioning: Parts reach final performance at 1.5-3.5% equilibrium water content. Can be accelerated in hot, humid environments (e.g., 50°C, 100% RH).
• Annealing: Heating parts in an oven at 60-80°C for up to four hours to relax internal stresses and improve dimensional stability.

4. Typical Applications

Celanese Zytel 73G15HSL PA6 is a versatile engineering material for demanding applications across various industries:

5. Safety, Handling, and Disposal

Responsible management of Zytel 73G15HSL PA6 throughout its lifecycle is essential for safety and environmental protection.

5.1 Safe Handling

• Protective Equipment and Ventilation: Always use proper protective equipment and ensure adequate ventilation.
• Temperature and Residence Time Control: Limit residence time and temperature in the machine barrel to prevent degradation and fume generation.
• Molten Resin Hazards: Contact with molten resin can cause severe burns. Be aware of potential violent ejection from the nozzle due to trapped gases.
• Purging Procedures: Follow proper purging procedures to minimize splattering of melt.
• Material Safety Data Sheets (MSDS/SDS): Consult relevant MSDS/SDS for detailed safety information before processing.

5.2 Storage

• Moisture-Proof Packaging: Stock PA materials in moisture-proof packaging to prevent moisture absorption.
• Impact of Improper Storage: Exposure to humidity leads to increased moisture content, requiring longer drying times.

5.3 Disposal

• Recycling: Good melt stability generally allows for recycling of properly handled production waste.
• Incineration with Energy Recovery: Preferred option if recycling is not feasible, in appropriately equipped installations.
• Local Regulations: Always comply with all local regulations governing waste disposal.