Polybutylene terephthalate has approved itself in various applications thanks to its exceptional properties such as high dimensional stability, minimal moisture absorption, excellent electrical insulation, high heat distortion temperature and solid long-term thermal stability
According to Lanxess in 2010 global PBT capacity will increase to a million tons. Considerable part of produced PBT is processed into compounds, e.g. reinforced with glass-fiber or converted into fireproof product due to introduction of flame retardants. PBT mixing with other plastics such as PET is also commonly used in order to modify PBT compounds properties range.
PBT plastics are mostly demanded in automotive and E&E industries: in 2008 automotive industry accoundet a half of PBT compounds volume consumed in Europe and E&E followed with around a quarter of consumed volume.
High-flow PBT grades
In recent years the development of high-flow PBT compounds become one of the major advancing in PBT development. High-flow PBT products of Pocan® Xtreme Flow (XF) series form Lanxess have a great market success and became very popular.
At shear rate distinctive for molding, Pocan® DP B 3235 XF viscosity is half as much as for convenient PBT Pocan® B 3235 grade. Furthermore parts made of Pocan® DP B 3235 XF maintain their mechanical properties. In fact Pocan® XF parts have more advantages than convenient PBT parts: lower (5 percent) density and improved hydrolysis resistance.
High-flow materials allow to cut production costs as lower viscosity lead to lower operating temperatures. This results in reduction of holding pressure and cycle times down to 20 percent allowing plastics processors to save time and money.
Pocan® Xtreme Flow polymers have approved themselves in various E&E and automotive products as well as appliance components such as plug connectors, extension cords, sockets and other functional engineering parts bearing high loads
Tough fire safety requirements
In recent years increased attention to safety and legislation changes led to exceptional higher demand for flame retardant PBT materials.
Lanxess introduces Pocan® DP CF2200, fireproof, PBT+PC grade modified with elastomers meeting all fire safety requirements. Due to its excellent dimensional stability combined with fine chemical resistance, toughness and flowability Siemens chose Pocan® DP CF2200 for hosing of its automated control systems.
Recently we could see increase in demand for fireproof halogen-free PBT driven by EU environmental directives and global trend for green products. Pocan® DP 2004 is an example of non-reinforced fireproof halogen-free PBT grade. Pocan® DP BFN 4230 is a 30% glass-filled material. Among other applications it is also used for production of functional parts of alternating current tubular drives.
Alternative to metals
Nowadays in applications with operating temperatures lower than 200°C there is a trend for substitution of plate and molded metal with high-filled PBT grades. Cost saving parts made of high-filled PBT provide wider design opportunities featuring lower weight. Also metal parts require expensive and labour-consuming machining (e.g. deburring) and corrosion protection. Metal substitution trend is also supplied by metal and energy price surge.
Thanks to excellent strength and stiffness high-filled PBT grades ideally suit for parts exposed to high loads with Pocan® T 7391 45% glass-filled PBT+PET grade being an example of such material. The plastic applied for production of stator and rotor in vacuum cleaner motors.
Thanks to high-flow PBT grades development it became possible to increase glass fiber content. Pocan® DP B 3160 XF, 60% glass-filled is the first commercial PBT grade with so high glass content. Potential applications include bails, engineering parts, housings, end connections for light self-contained generator, running boards and so on.
High hydrolysis resistance
Requirements to hydrolysis resistance are becoming tougher particularly in automotive industry. This concerns to grades applied for safety elements such as airbag connectors and covers, pretensioners and power steering systems on one hand and underhood connectors, plugs and covers on other hand. Here PBT mechanical properties such as impact viscosity, strength and stiffness must be maintained within the whole vehicle service life in order to parts keep their performance. That is why various PBT grades with exceptional wearing properties under tough hydrolysis is being developed. Among them is Pocan® DP 7139 from Lanxess.
PBT compounds represent ultramodern materials keeping innovative potential for years. Undoubtedly, promising PBT compounds will keep its development rates along with other engineering plastics. Lanxess offers wide PBT compounds portfolio for various requirements: high-filled and high-flow, fireproof and hydrolysis resistant PBT grades designated for processing optimization and a saving to the consumers.
Dr. Matthias Bienmuller, Pocan and FR-Durethan development manager
Dr. Martin Wanders, Pocan strategic marketing manager at Lanxess Semi-Crystalline Products