Nylon 6 vs Nylon 66 — Engineering Plastic Selection Guide

Chemical Structure Differences

The fundamental difference between PA6（ナイロン6） そして PA66 (Nylon 66) lies in their molecular structure:

• Nylon 6: Made from caprolactam, has 6 carbon atoms in each repeating unit. Less crystalline structure.
• Nylon 66: Made from hexamethylenediamine and adipic acid, has two 6-carbon chains. More crystalline structure.

機械的特性の比較

プロパティ	PA6	PA66
引張強度	70-85 MPa	80-100 MPa
曲げ弾性率	2.5-3.0 GPa	2.8-3.5 GPa
破断伸度	30-100%	15-60%
Notched Izod Impact	50-100 J/m	40-80 J/m
融点	220°C	260°C
HDT at 1.8 MPa	70°C	90°C

水分吸収

Moisture absorption is critical for nylon applications:

Condition	PA6	PA66
At 50% RH	2.5-3.0%	2.0-2.5%
Saturation	8-10%	6-8%

Processing Characteristics

Nylon 6 Processing

• Melting Point: 220°C
• Processing Range: 240-280°C
• 金型温度： 40-80°C

Nylon 66 Processing

• Melting Point: 260°C
• Processing Range: 280-320°C
• 金型温度： 60-90°C

Applications by Material

Nylon 6 Applications

• Gears and sprockets
• Industrial monofilament
• Film and packaging
• Consumer products

Nylon 66 Applications

• Automotive under-hood components
• Electrical connectors
• High-temperature bearings
• Precision mechanical components

Reinforced Grades

Both materials are commonly reinforced with glass fiber:

グレード	PA6 + GF30	PA66 + GF30
引張強度	140-160 MPa	170-200 MPa
HDT (1.8 MPa)	205°C+	250°C+
水分吸収	1.0-1.5%	0.8-1.2%

Selection Summary

Choose Nylon 6 when:

• Impact resistance is critical
• Cost sensitivity is high
• Operating temperatures are moderate

Choose Nylon 66 when:

• Higher mechanical strength is required
• Elevated temperatures are expected
• Dimensional stability is critical