| The electronic and electrical industries have been facing increased demand for halogen- and phosphorus-free alternatives to flame retardancy in their products. For electrical applications, a combination of high-flame retardancy and good electrical properties (namely a high CTI value) is necessary. The higher the CTI value the lower the wall thickness of the part can be, leading to a reduction in material and cycle times as well as cost.
PolyOne, USA, an international polymer services company with operations in thermoplastic compounds, speciality resins, speciality polymer formulations, engineered films, colour and additive systems, has recently supplied an electrical appliance customer with high-flow, halogen- and phosphorus-free flame-retardant (FR) unfilled and reinforced Bergamid� PA6 and PA6/66 compounds. PolyOne�s Bergamid� flame retardant compounds have CTI values up to and above 500V. Flame-retardant materials with specific performance and colours were requested for the different parts of the electrical socket, including both the inner and outer housings. As well as halogen-free FR compounds and good electrical properties, good processability and easy-flow was also critical for the customer due to the thin wall sections of the electrical parts.
The electrical socket was composed of three different parts, each with their individual requirements and specified colours:
- The inner housing was composed of a halogen- and phosphorus-free flame retardant PA66/6 copolymer in a light grey: Bergamid AB700 UF grey. In addition to UL94 V-0 performance, tests with glow wire (according to IEC 695-2-1) gave 960�C at 1.6mm as required by the customer;
- The dark grey outer housing requirements of glow wire 850�C at a thickness of 1.6mm and a good dimensional stability were met with a flame-retardant PA6 filled with a mixture of glass fibre and glass beads: Bergamid B70 G/GK15 UF grey;
- The material for black, green and blue push buttons is a very easy-flowing and fast crystallising PA6: Bergamid B70 S, used to avoid any difficulties during the injection molding process due to the thin wall thickness.
New grades of flame-retardant Bergamid PA 6 and PA66 compounds have been developed offering good electrical and processing properties and meeting the customers requirements in regards to mechanical properties. Good colourability and short cycle times are also characteristic of these compounds.
|
