Liquid crystalline or thermotropic polyesters capable of forming an anisotropic melt are known high performance materials useful for manufacturing films, fibers, molded articles and like items. While these materials typically exhibit superior temperature resistance and mechanical properties as compared to commodity resins, they are often times difficult to synthesize and melt-process due to a tendency to become intractable if the composition is not carefully controlled, or alternatively, desirable properties as aforementioned can be lacking if the ratio and/or selection of components is not within critical ranges.
Various attempts have been made to improve the processability and/or mechanical properties of liquid crystalline polyesters, including by the incorporation of amide linkages into such polymers.
U.S. Pat. No. 4,282,842 discloses poly(esteramides) prepared from an aromatic dicarboxylic acid, ethylene glycol, and a p-acylaminobenzoic acid. A similar disclosure is Japanese Publication 54-125271. European Patent Application No. 79301276.6 (Publication No. 0 007 715) discloses melt processable fiber-forming poly(esteramides) comprising residues of one or more aminophenols selected from p-aminophenol and p-N-methylaminophenol and residues of one or more dicarboxylic acids. The poly(ester-amide) disclosed contains a balance of linear difunctional residues and dissymmetric difunctional residues derived from either the aminophenols or their acids. The linear difunctional residues and dissymmetric difunctional residues are chosen so as to give a product which melts below its decomposition temperature and exhibits optical anisotropy in the melt.
U.S. Pat. No. 3,859,251 discloses a poly(ester-amide) which comprises 50 to 100 mole percent of the moiety derived from an acyclic aliphatic dicarboxylic acid.
U.S. Pat. No. 3,809,679 discloses poly(ester-amides) consisting of 10 to 90 mole percent of recurring structural units derived from a dicarboxylic acid dihalide and a dihydroxy compound of a specified formula and 10 to 90 mole percent of recurring structural units derived from a dicarboxylic acid dihalide and a diamino compound of a specified formula. The poly(ester-amides) described specifically exclude moieties derived from aromatic hydroxyacids, such as the 6-oxy-2-naphthoyl moiety included in the poly(ester-amide) of the present invention.
Commonly assigned U.S. Pat. No. 4,330,457, incorporated herein by reference, discloses melt processable poly(ester-amides) capable of forming an anisotropic melt phase derived from 6-hydroxy-2-naphthoic acid, dicarboxylic acid, and aromatic monomer capable of forming an amide linkage. The resulting poly(ester-amide) exhibits a melting temperature below approximately 400.degree. C.
Other poly(ester-amides) are disclosed and claimed in U.S. Pat. Nos. 4,966,956; 4,355,132 and 4,339,375. The '956 patent teaches a four-component poly(esteramide) including 4-oxybenzoyl, biphenol, an amide-forming monomer and either terephthaloyl or isophthaloyl moieties.
Commonly assigned U.S. Pat. No. 4,473,682, incorporated herein by reference, discloses melt processable polyesters capable of forming an anisotropic melt comprising a relatively low concentration of 6-oxy-2-naphthoyl moiety, 4-oxybenzoyl moiety, 4,4'-dioxybiphenyl moiety, and terephthaloyl moiety. This polyester forms an atypical highly tractable anisotropic melt phase.
Commonly assigned U.S. Pat. No. 4,351,917, incorporated herein by reference, discloses a melt processable poly(ester-amide) which is capable of forming an anisotropic melt phase derived from 6-hydroxy-2-naphthoic acid, an aromatic moiety capable of forming an amide linkage, and optionally, other aromatic moieties derived from aromatic hydroxyacid.
Commonly assigned U.S. Pat. No. 4,351,918, incorporated herein by reference, shows a melt processable poly(ester-amide) which is capable of forming an anisotropic melt phase derived from 6-hydroxy-2-naphthoic acid, other aromatic hydroxyacid, carbocyclic dicarboxylic acid, and aromatic monomers capable of forming an amide linkage.