Abstract: Disclosed is a method for producing a liquid crystal polyester, which includes the steps of: (1) polycondensing a mixture of 70.5 to 71.5 mol % of a compound represented by the defined formula (I) (for example, 4-acetoxybenzoic acid) with 28.5 to 29.5 mol % of a compound represented by the defined formula (II) (for example, 6-acetoxy-2-naphthoic acid) to form a prepolymer, wherein the prepolymer has a flow initiation temperature of 200° C. or higher, and the mixture is polycondensed until reaching the temperature which is at least 30° C. lower than the polycondensation temperature; (2) removing the prepolymer in a molten state, followed by solidification and further grinding to produce prepolymer particles; and (3) subjecting the prepolymer particles to a heat treatment at 200 to 310° C. under circulation of an inert gas while remaining in a solid phase state.

Abstract: The present invention provides a method for producing a polyethersulfone fiber, the method comprising the steps of discharging an electrically charged solution comprising a polyethersulfone and a solvent from a container; and drawing the charged solution by electrical attraction in an electrical field generated between the solution and an electrically charged collecting means having the opposite charge of the solution, while evaporating at least a portion of the solvent to form a polyethersulfone fiber. The fiber obtained in the present invention has a small average fiber diameter and can be made into a thin fiber cloth.

Abstract: According to the present invention, an aromatic polysulfone resin is offered which is suitable as film material, especially in porous membranes. The aromatic polysulfone resin of the present invention has a reduced viscosity of 0.55-0.65 dL/g, and preferably 0.58-0.62 dL/g, number average molecular weight (Mn) of 22000 or more, and preferably 23500 or more, and a value of the ratio of weight average molecular weight (Mw) relative to number average molecular weight (Mn) of 2.54 or less, and preferably 2.50 or less.

Abstract: An object of the present invention is to provide a porous membrane having excellent heat resistance and acid resistance. A porous membrane is constituted by a liquid crystal polyester and a polymer other than the liquid crystal polyester. A liquid crystal polyester having a reduced viscosity of 0.40 dL/g or more is used as the liquid crystal polyester. A polymer having a reduced viscosity of 0.40 dL/g or more is used as the polymer other than the liquid crystal polyester. The content of the polymer other than the liquid crystal polyester is adjusted from 10 to 40 parts by mass based on 100 parts by mass of the liquid crystal polyester.

Abstract: The present invention relates to a porous membrane which contains aromatic polysulfone resin that has a reduced viscosity of 0.56-0.78 dL/g, and a hydrophilic polymer.

Abstract: The present invention provides a method for producing a liquid-crystalline polyester powder, the method comprising: carrying out melt polycondensation of monomers and/or its acylated monomers to obtain a corresponding polyester having a flow initiation temperature of 240 to 300° C.; spreading and solidifying the polyester so as to be a layer thereof with a thickness of 1 cm or more: crushing the solidified substance to obtain a powder having a volume average particle diameter of 3 to 30 ?m; and subjecting the powder to a heat treatment to obtain a powder having a flow initiation temperature higher than the flow initiation temperature of the liquid-crystalline polyester after the melt polycondensation.

Abstract: The present invention provides a liquid-crystalline polyester having a structural unit represented by the formula (i), a structural unit represented by the formula (ii) and a structural unit represented by the formula (iii): wherein Ar1 is, at each occurrence, a member selected from the group consisting of a 2,6-naphthalenediyl group, a 1,4-phenylene group and a 4,4?-biphenylene group; and Ar2 and Ar3 are, at each occurrence, a member selected from the group consisting of a 2,6-naphthalenediyl group, a 1,4-phenylene group, a 1,3-phenylene group and a 4,4?-biphenylene group; wherein 40% by mole or more of all the groups Ar1, Ar2 and Ar3 are 2,6-naphthalenediyl groups; and wherein the polyester has a flow initiation temperature of from about 280 to about 320° C.

Abstract: A liquid crystalline polyester resin composition is provided, by which a molded article with an enhanced specific modulus can be produced. The liquid crystalline polyester resin composition comprises mica fillers in an amount of 15 to 30 parts by mass and carbon fibers with specific volume resistance of 108 ?cm or more in an amount of 5 to 20 parts by mass with respect to 100 parts by mass of the liquid crystalline polyester.

Abstract: The present invention provides a liquid crystalline polyester resin composition suitable for an optical pickup unit. The composition comprises a liquid crystalline polyester, a mica and a hollow filler. Using the liquid crystalline polyester resin composition, an optical pickup unit with a high soldering resistance and a high torsional elastic modulus can be produced while suppressing breakage of the hollow filler in the composition.

Abstract: The present invention provides a method for producing a liquid-crystalline polyester powder, the method comprising: carrying out melt polycondensation of monomers and/or its acylated monomers to obtain a corresponding polyester having a flow initiation temperature of 240 to 300° C.; spreading and solidifying the polyester so as to be a layer thereof with a thickness of 1 cm or more: crushing the solidified substance to obtain a powder having a volume average particle diameter of 3 to 30 ?m; and subjecting the powder to a heat treatment to obtain a powder having a flow initiation temperature higher than the flow initiation temperature of the liquid-crystalline polyester after the melt polycondensation.

Abstract: A liquid crystalline polyester resin composition is provided, by which a molded article with an enhanced specific modulus can be produced. The liquid crystalline polyester resin composition comprises mica fillers in an amount of 15 to 30 parts by mass and carbon fibers with specific volume resistance of 108 ?cm or more in an amount of 5 to 20 parts by mass with respect to 100 parts by mass of the liquid crystalline polyester.

Abstract: The present invention provides a dispersion in which aromatic polysulfone resin particles are dispersed in water. The aromatic polysulfone resin particles comprises a aromatic polysulfone resin having oxygen-containing groups selected from among hydroxyl groups and oxyanion groups in an amount of 1.6 or more groups relative to 100 repeating units forming the aromatic polysulfone resin; and have the volume average particle diameter of 50 ?m or less. The dispersion is less likely to cause settlement of the aromatic polysulfone particles and is suited for use as an aqueous coating material.

Abstract: The present invention provides a liquid crystalline polyester resin composition suitable for an optical pickup unit. The composition comprises a liquid crystalline polyester, a mica and a hollow filler. Using the liquid crystalline polyester resin composition, an optical pickup unit with a high soldering resistance and a high torsional elastic modulus can be produced while suppressing breakage of the hollow filler in the composition.

Abstract: The present invention provides a cleaning composition used for cleaning a device for producing a liquid crystalline polyester, the composition comprising (A) glycols, (B) amines and (C) a compound selected from the group consisting of cyclic esters, amides and sulfoxides, wherein the content of the component (B) is 5 to 40% by weight and the content of the component (C) is 5 to 30% by weight, both being with respect to the total weight of the cleaning composition.

Abstract: The present invention provides a liquid-crystalline polyester having a structural unit represented by the formula (i), a structural unit represented by the formula (ii) and a structural unit represented by the formula (iii): wherein Ar1 is, at each occurrence, a member selected from the group consisting of a 2,6-naphthalenediyl group, a 1,4-phenylene group and a 4,4?-biphenylene group; and Ar2 and Ar3 are, at each occurrence, a member selected from the group consisting of a 2,6-naphthalenediyl group, a 1,4-phenylene group, a 1,3-phenylene group and a 4,4?-biphenylene group; wherein 40% by mole or more of all the groups Ar1, Ar2 and Ar3 are 2,6-naphthalenediyl groups; and wherein the polyester has a flow initiation temperature of from about 280 to about 320° C.

Abstract: The present invention provides a method for producing a liquid crystal polyester fiber, the method comprising a step of spinning a liquid crystal polyester that has a glass transition temperature and a melting point, both observed by differential scanning calorimetry, and that has a flow initiation temperature of 250° C. or higher, followed by a heat treatment at 230° C. or lower. Even though the heat treatment is conducted at a low temperature, the obtained liquid crystal polyester fiber has a high strength.

Abstract: The present invention provides a method for producing a polyethersulfone fiber, the method comprising the steps of discharging an electrically charged solution comprising a polyethersulfone and a solvent from a container; and drawing the charged solution by electrical attraction in an electrical field generated between the solution and an electrically charged collecting means having the opposite charge of the solution, while evaporating at least a portion of the solvent to form a polyethersulfone fiber. The fiber obtained in the present invention has a small average fiber diameter and can be made into a thin fiber cloth.

Abstract: A method for producing a laminate comprising a liquid-crystalline polyester resin layer and a metal foil was provided. The laminate has a reduced curling, and can be obtained by preparing a resin layer containing a liquid-crystalline polyester on one side of a metal foil, winding the resin layer with the metal foil into a roll so that the resin layer is outward and subjecting the roll to a heat treatment.

Abstract: The present invention provides a method for producing a liquid crystalline polyester fiber, the method comprising the steps of discharging an electrically charged solution comprising a liquid crystalline polyester, a fiber-forming polymer and a solvent from a container; and drawing the charged solution by electrical attraction in an electrical field generated between the solution and an electrically charged collecting means having the opposite charge of the solution, while evaporating at least a portion of the solvent to form a liquid crystalline polyester fiber. The fiber obtained in the present invention has a small average fiber diameter and can be made into a thin fiber cloth with high density.