Arnite(R); Thermoplastic Polyester

Arnite® thermoplastic polyesters are a broad line of engineering materials based on polybutylene terephthalate (PBT) and polyethylene terephthalate (PET). PBT is made by a two-step reaction. The first step is a transesterification of DMT and butanediol, which is followed by a polycondensation process. PBT is a semi-crystalline material with a melting point (Tm) of the crystalline phase at 223°C (433°F). The Arnite® PBT product line covers unfilled and glass fiber reinforced grades. Both unfilled and glass filled grades are available with flame retardant additives. Besides PBT, the Arnite® product line includes PET grades for applications which require higher strength or higher heat resistance. Various glass fiber grades are available. DSM has a long history in the supply and support of polyesters providing experience, know-how, and technical service.Arnite PBT is supplied pre-dried in sealed packaging and can be processed directly from the bag. Polyesters are sensitive to hydrolytic attack at elevated temperatures and, therefore, low moisture levels should be maintained during injection molding and extrusion. Maximum 0.03% moisture content for Arnite PBT and 0.02% for Arnite PET is recommended.

Arnite® Properties
Typical properties in which PBT differentiates itself from other engineering plastics are:

• low moisture absorption (PBT absorbs 0.45% maximum during immersion in water)
• good dimensional stability (the final dimensions of a plastic part are primarily influenced by absorbed moisture and, in this respect, Arnite PBT outperforms polyamides)
• excellent chemical resistance - (due to its semi-crystalline structure, PBT exhibits an excellent Environmental Stress Crack and chemical resistance, which is the limiting property of amorphous materials such as polycarbonate)
• good heat and heat aging resistance
• high creep resistance which leads to excellent pin retention for connectors.

Arnite® Components
PBT reaches a RTI (Relative Temperature Index) of 130 to 140°C (266 to 284°F), and its semi-crystalline structure in combination with glass fiber reinforcement yields heat distortion values of greater than 200°C (392°F). Within electrical applications Arnite demonstrates:

• good electrical properties, which is illustrated by a CTI > than 600 V
• high strength – PBT reinforced with 30% glass fibers has a tensile strength of 21,000 psi
• easy molding – like most semi-crystalline materials PBT has an easy flowing melt enabling thin wall molding required for connectors, capacitor housings, and bobbins. The high crystallization rate also means fast cycles times compared to other engineering thermoplastics.

Arnite® Application Areas
The range of available grades covers numerous applications within the automotive engineering, electrical engineering and electronics, packaging, household, mechanical engineering and high precision engineering industries.

AUTOMOTIVE
fuse boxes, sensors, door handles, brake booster valve housings

ELECTRICAL / ELECTRONICS
connectors, switches, circuit breakers, current devices, motor end caps, rotors and stators, compressor components

DSM Engineering Plastics, 2267 West Mill Road, PO Box 3333. Tel: 800-333-4237; Fax: 812-435-7702 .