The present invention relates to an aromatic polyester having the following structural units (1) to (5) and a molded article using the aromatic polyester. ##STR2##
wherein Ra, Rb, Rc, Rd, Re and Rf each independently represents a lower alkyl group, lower alkoxy group, phenyl group or halogen atom, and n represents an integer from 0 to 3.
Conventionally, aromatic polyesters having the above-described structural units (1), (2), (4) and (5) have been known. Recently, aromatic polyester also having the structural unit (3) have been suggested. For example, an aromatic polyester has been disclosed in which the ratio of (2) to (3) (=molar ratio of (2) to (3), that is, ratio of number of unit (2) to number of unit (3) in the aromatic polyester. Hereinafter in this specification, the molar ratio of a unit to another unit is indicated by using "/". For example, the molar ratio of (2) to (3) is indicated by as (2)/(3)) is 1.0 and (4)/(5) is 2.33 (JP-A-63-57633).
However, the above-described aromatic polyester has problems that, when molded, the ratio of the molding contraction coefficient along the vertical direction (TD direction) to the flow to the molding contraction coefficient along the flow direction (MD direction), that is TD/MD ratio, is remarkably large, and deformations such as warping of molded articles and the like occur.
On the other hand, an aromatic polyester having excellent molding property at lower temperature is also disclosed in which 1.ltoreq.(2)/(3).ltoreq.9 and 1.86.ltoreq.(4)/(5).ltoreq.4 (JP-B-7-98859). In this publication, it is also disclosed that, when (2)/(3)&lt;1, namely, (3) is surplus as compared with (2), molding property of the aromatic polyester at lower temperature has remarkably lowered.
Further, an aromatic polyester having excellent molding property at lower temperature is also disclosed in which 1.ltoreq.(2)/(3).ltoreq.9 and 0.3.ltoreq.(4)/(5).ltoreq.1. It is also disclosed that, when (2)/(3)&lt;1, namely, (3) is surplus as compared with (2), molding property of the aromatic polyester at lower temperature has remarkably lowered (JP-A No. 10-95839).
USPTO Backgrounds
USPTO Backgrounds