1. Field of the Invention
The invention relates to a liquid crystalline polyester composition excellent in moldability and a molded article thereof.
2. Description of the Related Art
Along with miniaturization and advancement of electric and electronic parts, a resin material for producing these parts have been required to have advanced properties such as high fluidity, high heat resistance, inflammability, chemical resistance, high strength, and the like and various thermoplastic resins and compositions thereof have been developed. A liquid crystalline polyester among thermoplastic resins can satisfy the above-mentioned properties in high levels and is characterized in that they are particularly excellent in fluidity. Owing to such a characteristic, a liquid crystalline polyester is relatively easy to be processed by melt molding for parts having thin portions and accordingly has been used widely for producing thin molded bodies and molded bodies with complicated shapes.
However, at the time of producing a molded article with a complicated shape from a thermoplastic resin or thermoplastic resin composition by melt molding, molds used for the melt molding (generally, dies) and a molded article obtained in the dies are inferior in the mold releasing property and so-called a mold releasing failure sometimes tends to occur easily. If such a mold releasing failure occurs, the obtained molded article is deformed and thus it becomes difficult to obtain a molded article with a desired shape or it becomes difficult to take the deformed molded article out of the dies, resulting in decrease of the productivity of the molded article.
As a method for solving such problems, a method of coating the inner surface of dies with a chemical agent having a mold releasing property for the dies and a molded article, or a method of forming a protective film on the inner surface of the dies by carrying out heat treatment or the like, if necessary, after the coating, has been employed in general. In this case, the chemical agent to be applied to the inner surface of the dies is generally called as “external release agent”. On the other hand, an additive capable of improving the mold releasing property of a molded article to be obtained by adding to a thermoplastic resin is sometimes employed. Such an additive is generally called as “internal release agent”. When the internal release agent is used, it is advantageous in a point that the productivity of melt molding is not lowered as compared with the case of using the external release agent that is required to apply to the inner surfaces of dies every prescribed times of melt molding.
For example, Japanese Patent Application Laid-Open (JP-A) No. 2-208353 (Claims and Examples) discloses ester of pentaerythritol stearic acid as an internal release agent to be used for melt molding using a liquid crystalline polyester and it discloses that use of such a compound can prevent discoloration of a molded article and gas emission at the time of melt molding though it is excellent in mold releasing property as compared with glycerin tristearate or the like which has conventionally been used as an internal release agent.