Polyplastics launches low-warpage PBT grade for automotive applications

The Polyplastics Group (Tokyo) has launched a Duranex polybutylene terephthalate (PBT) grade that combines the properties traditionally found in PBT with other important performance attributes. Duranex 750AM is a 30% glass-reinforced, flame-retardant (FR) grade with low warpage, high rigidity and heat and moisture resistance. Duranex750 AM is suited for automotive communication devices and high-pressure parts for electric vehicles (EVs) and hybrid electric vehicles (HEVs).

Polyplastics' Duranex polybutylene terephthalate grade

It has been difficult to satisfy requirements for both flame and moisture resistance because moisture resistance typically decreases with the addition of an FR component, explained Polyplastics. There has been increasing demand for FR materials in the automotive market for use in communication devices and high-pressure parts for EVs and HEVs. These materials also must meet the auto industry’s need for durability and formability. Duranex 750AM and other PBTs also meet the demands of electrical and electronics applications.

Polyplastics can produce low-warpage PBT materials such as Duranex 750AM via three methods:

  • The anisotropy of the shrinkage rate can be reduced by using spherical and plate-like fillers with low aspect ratios rather than fiber fillers. This reduces warpage, but can also adversely affect mechanical strength.
  • The absolute value of the shrinkage rate can be reduced by forming alloys with amorphous resins such as PC and SAN. This method results in a small reduction in mechanical strength, while the amorphous resin also has an effect on thermal properties and other factors.
  • Improving flowability and reducing pressure distribution (shrinkage rate distribution) inside the cavity can reduce warpage, though not as much as the aforementioned two methods. 

The Polyplastics Group’s product portfolio includes PBT, polyoxymethylene (POM), polyphenylene sulfide (PPS), liquid crystal polymer (LCP) and cyclic olefin copolymer (COC).

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