Introduction

Polyester-based liquid crystal polymer (LCP) is one of the most attractive materials in the field of engineering thermoplastics because of its superior heat resistance, stiffness, accuracy of dimensions, moldability, and excellent balance of these properties. LCP is recently expanding its applications, in particular, those for the precision electronic parts appropriate for surface mount technology (SMT). The historical perspective of LCP is outlined below.

In 1972, Cottis and coworkers at Carborundum patented wholly aromatic polyesters based on p-hydroxybenzoic acid (HBA), 4,4 ?- dihydroxybiphenyl (DHB), and terephthalic acid (TPA), one of which was later commercialized as EKKCEL I-2000 ^[1]. In 1974, Kuhfuss and coworkers at Eastman Kodak reported a new polyester based on HBA and poly(ethylene terephthalate) (PET), which was later marketed under the code of X-7G. X-7G is the first thermotropic liquid crystalline polymer to be fabricated by injection molding or melt spinning ^[2]. However, then Eastman Kodak withdrew its plan of marketing of X-7G and changed the target with a wholly aromatic polyester commercialized as TITAN (THERMX ) in 1996. As described later, it was acquired by DuPont in 2003.

Sumitomo Chemical bought the EKKCEL business from Carborundum and began to supply the product in the Japanese market under the trademark of EKONOL in 1979. Sumitomo Chemical has manufactured EKONOL (SUMIKASUPER LCP ), using a kneader-type polycondensation reactor ^[3]. The technology of Carborundum was also sold to...