A type of high-modulus-low-shrinkage activated PET industrial yarn and preparing method thereof are disclosed. The preparing method is to manufacture filament from a modified polyester, which is the product of the esterification and the successive polycondensation reactions of evenly mixed terephthalic acid, ethylene glycol and tert-butyl branched heptanediol, through a series of processes composed of viscosity enhancing by solid state polycondensation, melting, metering, extruding, cooling, oiling, stretching, heat setting, relaxation heat-treating, oiling with activation oil, winding and pre-activation treatment. The relaxation heat-treating indicates passing the modified polyester yarns through a space with a certain temperature within 200-220° C. under a proper relaxation state; and the proper relaxation state means a 3.0-5.0% of overfeed for the winding. The improvement of activator efficiency by importing the tert-butyl branched diol into the polyester, together with the synergistic effect of heat setting temperature and high winding overfeed rate, will reduce the fiber thermal shrinkage.

Disclosed herein are processes of making furan-based polyamides using solvent-free melt condensation of a diamine and an ester derivative of 2,5-furandicarboxylic acid with a C.sub.2 to C.sub.12 aliphatic diol or a polyol. The processes comprise a) forming a reaction mixture by mixing one or more diamines, a diester comprising an ester derivative of 2,5-furandicarboxylic acid with a C.sub.2 to C.sub.12 aliphatic diol or a polyol, and a catalyst, such that the diamine is present in an excess amount of at least 1 mol % with respect to the diester amount; and b) melt polycondensing the reaction mixture in the absence of a solvent at a temperature in the range of 60° C. to a maximum temperature of 250° C. under an inert atmosphere, while removing alkyl alcohol to form a furan-based polyamide, wherein the one or more diamines comprises an aliphatic diamine, an aromatic diamine, or an alkylaromatic diamine.

A catalyst composition for a polyester manufacturing process, comprising a titanium catalyst and/or an antimony catalyst as main catalyst, and either (i) at least one co-catalyst A, or (ii) at least one co-catalyst B and at least one co-catalyst C, or (iii) a combination thereof, and wherein co-catalyst A is selected from the group consisting of a metal salt of an alkyl or an aryl phosphinic acid, or a metal salt of an alkyl or aryl diphosphinic acid, or a combination thereof, and co-catalyst B is selected from the group consisting of an alkyl or aryl phosphinic acid, an alkyl or aryl diphosphinic acid a combination thereof, and co-catalyst C selected from the group of a metal salt, a metal hydroxide or a metal organyl compound.

A type of fully dull polyester drawn yarns and a preparing method thereof are disclosed. The preparing method is to melt spinning a modified polyester with the fully drawn yarn (FDY) technique, and the modified polyester is a product of an esterification and successive polycondensation reactions of evenly mixed terephthalic acid, ethylene glycol, 2,5,6,6-tetramethyl-2,5-heptanediol, a fluorinated dicarboxylic acid, a matting agent, a calcined multiphase solid acid base powder and a doped Bi.sub.2O.sub.3 powder. The obtained fiber has an intrinsic viscosity drop of 18-26% when stored at 25° C. and R.H. 65% for 60 months. The method of improving the degradation performance of polyester fiber through the incorporation of 2,5,6,6-tetramethyl-2,5-heptanediol, the fluorinated dicarboxylic acid, the doped Bi.sub.2O.sub.3 powder and the calcined multiphase solid acid base powder is easy to operate.

A type of feather-like polyester fiber and a preparing method thereof are disclosed. The preparing method is to manufacture filament from a modified polyester through a POY process with a four-fold flat spinneret and a successive DTY processes, wherein said modified polyester is the product of the esterification and the successive polycondensation reactions of evenly mixed terephthalic acid, ethylene glycol, main-chain silicated diol and fluorinated dicarboxylic acid, and the spinneret is the one set with four-fold flat shaped orifices. The obtained fiber has a dye uptake of 89.6-93.7% when dyed at 130 C., and has an intrinsic viscosity drop of 13-20% when stored at 25 C. and R.H. 65% for 60 months. This invention is simple to apply and features a product with good dyeing and degradation performance.

A type of fully dull polyester drawn yarns and a preparing method thereof are disclosed. The preparing method is to melt spinning a modified polyester with the fully drawn yarn (FDY) technique, and the modified polyester is a product of an esterification and successive polycondensation reactions of evenly mixed terephthalic acid, ethylene glycol, 2,5,6,6-tetramethyl-2,5-heptanediol, a fluorinated dicarboxylic acid, a matting agent, a calcined multiphase solid acid base powder and a doped Bi.sub.2O.sub.3 powder. The obtained fiber has an intrinsic viscosity drop of 18-26% when stored at 25 C. and R.H. 65% for 60 months. The method of improving the degradation performance of polyester fiber through the incorporation of 2,5,6,6-tetramethyl-2,5-heptanediol, the fluorinated dicarboxylic acid, the doped Bi.sub.2O.sub.3 powder and the calcined multiphase solid acid base powder is easy to operate.

A process for producing a cationic dyeable polyester includes the steps of: (a) subjecting a combination of a bis-hydroxy alkyl terephthalate monomer of Formula (1) defined herein and an organic diacid monomer mixture which includes an aromatic dicarboxylic acid monomer and a sulfo group-containing aromatic dicarboxylic acid dyeable monomer to an esterification reaction to form an esterification reaction product; and (b) subjecting the esterification reaction product to a polycondensation reaction.

A type of feather-like polyester fiber and a preparing method thereof are disclosed. The preparing method is to manufacture filament from a modified polyester through a POY process with a four-fold flat spinneret and a successive DTY processes, wherein said modified polyester is the product of the esterification and the successive polycondensation reactions of evenly mixed terephthalic acid, ethylene glycol, main-chain silicated diol and fluorinated dicarboxylic acid, and the spinneret is the one set with four-fold flat shaped orifices. The obtained fiber has a dye uptake of 89.6-93.7% when dyed at 130 C., and has an intrinsic viscosity drop of 13-20% when stored at 25 C. and R.H. 65% for 60 months. This invention is simple to apply and features a product with good dyeing and degradation performance.

A bi-profiled fiber and preparing method thereof are provided. The bi-profiled fiber is manufactured through the steps of spinning melt metering, extruding via the composite spinneret, cooling, oiling, drawing, heat setting and winding, finally containing both double-cross monofilaments and circular monofilaments simultaneously. The bi-profiled fiber is made of the modified polyester, and the modified polyester is dispersed by matte agent and is composed of terephthalic acid segments, ethylene glycol segments and branched diol segments, and the branched diol segment has a structural formula of ##STR00001## where R.sub.1 and R.sub.2 are separately selected from the linear alkylene with 1-3 carbon atoms, R.sub.3 from the alkyl with 1-5 carbon atoms, and R.sub.4 from the alkyl with 2-5 carbon atoms. The matte agents is a mixture of amorphous titanium dioxide and amorphous silicon dioxide, or a mixture of calcium carbonate and amorphous silicon dioxide.

A polyethylene terephthalate resin composition which is characterized by having a manganese element content of 30 to 60 ppm, a potassium element content of 2 to 10 ppm, an antimony element content of 70 to 150 ppm, a molar ratio of metal elements to phosphorus element (M/P=(M1+M2/2)/P) satisfying formula (1), and a gelation ratio of 5% by weight or less:
0.6(M1+M2/2)/P1.3(1)
wherein M1 represents the content (mol/t) of a bivalent metal element selected from the group consisting of Mg, Mn, and Ca; M2 represents the content (mol/t) of a monovalent metal element selected from the group consisting of Li, Na, and K; and P represents the content (mol/t) of phosphorus element.