Abstract: A process for preparing polyesters, which comprises reacting (A) a difunctional carboxylic acid component containing at least 50 mol% of a naphthalene dicarboxylic acid and/or its ester-forming derivative, (B) a diol component containing an aromatic group and at least 50 mol% of a 4,4'-bis-(.omega.-hydroxyalkoxy)diphenylsulfone and (C) an aliphatic or alicyclic diol component, the molar ratio of component (B) to component (A) being 0.05-1, and the molar ratio of the sum of components (B) and (C) to component (A) being 1.1-3.0; and then polymerizing the resulting reaction product in the presence of a catalyst while distilling off the excess of the component (C) out of the reaction system, thereby to form a polymer having a reduced viscosity of at least 0.5.

Abstract: Naphthalate polyester filaments, yarns or fibers consisting essentially of a naphthalate polyester which has an intrinsic viscosity of 0.3 to 3.5 and a softening point of at least 200.degree. C, and in which at least 85 mol% of the total recurring units consist of units of the formula ##STR1## wherein n is 4 or 6, and having at least one diffraction peak at a Bragg scattering angle 2.theta. = 16.3.degree. -- 16.7.degree. and/or 2.theta. = 25.3.degree. - 25.8.degree. in their X-ray diffraction. These filaments, yarns or fibers are useful especially as an electrically insulating material, an elastomeric reinforcing material, a fluid filter material, a paper-making canvas and a fastener component material.Of these, filaments, yarns or fibers of poly(tetramethylene 2,6-naphthalate) are prepared by melt-spinning the polymer thereby to form undrawn filaments having a birefringence of at lest 0.01 and a density of not more than 1.

Abstract: A process for preparing a fired-retardant polyamide, which comprises polymerizing a carboxylic acid component consisting essentially of at least one naphthalene-dicarboxylic acid selected from the group consisting of naphthalene-2,7-dicarboxylic acid and naphthalene-2,6-dicarboxylic acid and/or its amide-forming derivative, and a halogen substituted-carboxylic acid and/or its amide-forming derivative, and an aliphatic diamine, the amount of said naphthalene dicarboxylic acid and/or its derivative being at least 40 mol% of the total acid component, and the amount of said halogen-substituted carboxylic acid being such that the halogen atom content of the polyamide is at least 0.13% by weight.

Abstract: Heat-resistant aromatic polyester filaments having heretofore unknown physical properties and a combination of excellent heat resistance and mechanical strength, which (1) is composed of an aromatic polyester in which at least 90 mole % of the structural units are ethylene-2,6-naphthalate units, (2) has a melting point at a constant length (Tm;.degree.C.) of at least 287.degree. C., (3) has a density (d)(g/cm.sup.3) of at least 1.370, (4) is insoluble in a phenol/orthodichlorobenzene mixed solvent (mixing ratio = 6/4 on the weight basis) at 160.degree. C. and (5) meets the requirements expressed by the following formulaeL(Tm - 280) = 400 (I).DELTA. n(d - 1.350) = 70 .times. 10.sup.-.sup.3 (II)L = .lambda.K/(B-b)cos .theta. (III)and the process for the preparation thereof.

Abstract: In the process for preparing alkenylbenzene by the catalytic reaction of alkylbenzenes and 1,3-butadiene in the presence of an alkali metal catalyst, the improvement which comprises effecting the preliminary contact of the freshly fed alkylbenzene with the reaction product of said catalyst reaction and thereafter catalytically reacting said alkylbenzene with said 1,3-butadiene.

Abstract: Fiber-forming polyamides are prepared by poly-condensing naphthalene-2,7-dicarboxylic acid and a straight-chain aliphatic diamine containing 4 to 13 carbon atoms and 15 to 50 mol% of another carboxylic acid and/or another diamine as a copolymerizing component.

Abstract: A method for stabilizing a polyester at least 80% of the recurring units of which in terms of number consist of tetramethylene terephthalate units or tetramethylene-2,6-naphthalate units, by incorporating into said polyester 0.001 to 10% by weight, based on the weight of the polyester, of at least one compound of the following formula (I) ##SPC1##This application is a continuation-in-part of application Ser. No. 548,988, filed Feb. 10, 1975, which in turn is a divisional application of Ser. No. 417,918 filed Nov. 21, 1973, now U.S. Pat. No. 3,904,578.

Abstract: According to this invention, during the formation of a fiber-forming polyester by the reaction of a dicarboxylic acid or its functional derivative with a glycol, an aromatic ortho-ester such as hexaphenyl ortho terephthalate is added to the molten polyester whereby a fiber-forming polyester of a low content of free carboxyl groups and diethylene glycol units is prepared. Moreover, the reaction rate of the polycondensation is greatly increased by selecting and using a suitable aromatic ortho-ester and thus there can be obtained a fiber-forming polyester of a very high molecular weight.

Abstract: In a process of preparing aromatic polyesters from (A) aromatic dicarboxylic acids and (B) diphenols by the solid phase polymerization method, the speed of the solid phase polymerization reaction can be enhanced to a marked degree by copolymerizing (C) an aliphatic dihydroxy compound, and in this case the amounts in which the components (B) and (C) are used, based on (A), being 70 - 105 mol % of (B) and 1 - 50 mol % of (C), with the total amount of (B) and (C) corresponding to 100 - 130 mol % of (A).

Abstract: A thermally stable extrusion-molded article characterized by (1) consisting of a substantially linear polyester in which at least 90 mol% of the total recurring units consist of tetramethylene 2,6-naphthalate units, (2) having a density not in excess of 1.318, and (3) being in the unstretched state.This article is prepared by extruding a melt of a substantially linear polyester in which at least 90 mol% of the total recurring units consist of tetramethylene 2,6-naphthalate units into the form of a molded structure, and cooling the extruded molded structure to room temperature, wherein during the period in which the extruded molded structure is cooled from at least 75%C. to room temperature, the cooling of the molded structure is performed rapidly so that the density of the molded structure does not exceed 1.318.

Abstract: A process for preparing a shaped article by melt-extruding a polyester containing tetramethylene naphthalene-2,6-dicarboxylate or hexamethylene naphthalene-2,6-dicarboxylate as a main recurring unit, wherein the extrudate is exposed to a temperature of 75.degree. to 450.degree.C. for 1 to 180 seconds immediately after extrusion.

Abstract: A process for preparing 2,6-dimethylnaphthalene by the selective isomerization of an isomeric mixture of dimethylnaphthalenes(DMN), characterized in that1. the weight ratio of DMN of group A which includes 2,6-DMN, 1,6-DMN, and 1,5-DMN to other DMN (not belonging to group A) in the isomerization reactant is adjusted to not more than 12,2. the weight percent of 2,6-DMN in the reaction product is adjusted to at least 27 based on the DMN of group A contained therein,3. the disproportionation ratio D (weight percent) of other DMN (not belonging to group A) and the conversion G (weight percent) of DMN of group A to other DMN satisfy the relation expressed by D.ltoreq. -0.9G + 6.76, and4. the residue in the crystallization step is recycled to the isomerization step.

Abstract: In the method wherein an alkenylation reaction product liquid obtained by the alkenylation reaction of an alkylbenzene and a C.sub.4 - C.sub.5 conjugated diene in the presence of alkali metal catalysts and containing unreacted alkylbenzene, alkali metal catalysts and organo-alkalimetal compounds is conveyed to a distillation zone at which said alkenylation reaction product liquid is separated by distillation to recover an alkenylbenzene-containing fraction and an unreacted alkylbenzene-containing fraction, the improvement which comprises adjusting the total of the concentrations of said alkali metal catalysts and organo-alkalimetal compounds in said alkenylation reaction product liquid introduced to the distillation zone so as to be 0.09 - 15 milligram atoms per kilogram of said product liquid, calculated as alkalimetal atoms, and thereafter conducting the distillation of said product liquid under conditions of non-addition of alcohols.

Abstract: In the process for preparing monoalkenylbenzenes by reacting an alkylbenzene and a C.sub.4 - C.sub.5 conjugated diene in the presence of an alkali metal catalyst while passing the reactants progressively through a series of successive reaction zones substantially isolated from each other under non-back-flow conditions, the reaction being carried out at this time while feeding said alkylbenzene and alkali metal catalyst to the first reaction zone and the conjugated diene separately to at least two of said zones, and thereafter withdrawing the reaction product from the final reaction zone of said series; the improvement which comprises (1) reacting the reactants including the alkylbenzene, C.sub.4 - C.sub.

Abstract: An aromatic polyester resin composition with inhibited coloration comprising (1) 100 parts by weight of an aromatic polyester resin composed mainly of tetramethylene arylcarboxylate units and polymerized by a titanium compound catalyst, (2) 5 to 100 parts by weight of a polycarbonate resin and (3) a coloration inhibiting amount of at least one phosphorus compound, and a method for inhibiting the coloring phenomenon of a resin composition comprising the polyester resin (1) and polycarbonate resin (2).

Abstract: A process for preparing alkenylbenzenes, which comprises reacting an alkylbenzene with 1,3-butadiene at elevated temperature in the presence of an alkali metal catalyst in the substantial absence of oxygen and moisture, characterized in that said catalyst is composed of1. 0.0005 to 0.03% by weight, based on the alkylbenzene, of metallic potassium, and2. metallic sodium in an amount expressed in percent by weight, based on the alkylbenzene, determined by the following relationship (i)-0.59x + 0.025 .gtoreq. Nawherein x is the amount expressed in percent by weight of the metallic potassium used.

Abstract: An electrically insulating material composed of an unstretched film of a substantially linear polyester at least 85 mol% of the recurring units of which consist of a hexamethylene naphthalene-2,6-dicarboxylate unit and which has an intrinsic viscosity, as measured on its ortho-chlorophenol solution at 35.degree.C., of at least 0.3.