A low chromatic aberration polyester different-shrinkage composite yarn is made of polyester POY yarn and polyester FDY composite yarn. The polyester POY yarn and polyester FDY yarn is obtained by spinning the polyester solution, the rupture strength of the low color polyester different-shrinkage composite yarn is 1.9 cN/dtex, the elongation at break is 30.05.0%, the crimp shrinkage is 2.503.0%, the network degree is 205/m, the color difference E is less than 0.200. In the invention, the magnesium ethylene glycol is relatively mild, the thermal degradation coefficient is small, the oligomers in the polymerization process is reduced, and the oligomers in the dissolution process are further reduced, so that the appearance of stains and streaks reduces during the dyeing and post-processing heat setting of the polyester fiber, which ensures the fiber's leveling and rubbing fastness.

Disclosed herein is a catalyst composition for a polyester manufacturing process. The catalyst composition includes a titanium catalyst and a co-catalyst A of formula (I), wherein R.sub.1 and R.sub.2 are each independently selected from methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl, and n-pentyl.

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A polyester obtained by the esterification of terephthalic acid and ethylene glycol and the polycondensation catalysed by a mixture of magnesium ethylene glycol and antimony ethylene glycol followed by granulation. In the polyester sections, the carboxyl end group is less than 15 mol/t, the mass percentage of oligomer is lower than 0.5%, and weight percentage of diethylene glycol is lower than 0.5%.

Provided is a method for producing a non-colored polyester with a high molecular weight. The method is to produce a polyester represented by a general formula (2). This method comprises: a first step of heating, under the presence of an antimony catalyst, a compound represented by the general formula (1) at a heating temperature in a range of from a melting point of the compound to a temperature that is 10 C. higher than the melting point; and a second step of heating a solid product or viscous product obtained after the first step at a heating temperature in a range of from the melting point of the compound represented by the general formula (1) to 270 C. ##STR00001##

A process for reducing diethylene glycol formation in polyethylene terephthalate includes (a) subjecting a mixture of bis(2-hydroxyethyl)terephthalate with aromatic polycarboxylic acid to an esterification reaction, and (b) subjecting the esterification reaction product to polycondensation.

The molecular weight of a semi-crystalline polyester including ethylene 2,5-furandicarboxylate units is increased in a process, including heating the semi-crystalline polyester during a solid state polymerization period. The temperature is at least 180 C. and is kept below the melting point of the semi-crystalline polyester whilst the semi-crystalline polyester is either under a flow of inert gas or under vacuum to obtain a solid state polymerized polyester. The temperature is continuously or periodically increased during the solid state polymerization period.

Disclosed is a biaxially stretched polyester film containing an antimony compound as a catalyst component, and a magnesium compound and a phosphorus compound as additives, in which an amount of metal antimony included in residues on a membrane filter having an average pore diameter of 0.1 m, after a solution in which 1 g of the biaxially stretched polyester is dissolved in 5 ml of hexafluoroisopropanol is filtered by the filter, is 10 to 100 mg per 1 kg of the biaxially stretched polyester.

A cinnamic acid polymer or copolymer that can be employed as a biorenewable alternative to a commodity polymer results from the polymerization of hydroxyalkyldihydroferulic acids, hydroxyalkylferulic acids, hydroxyalkyldihydrocoumaric acids, hydroxyalkylcoumaric acids, dihydroferulic acid, ferulic acid, dihydrocoumaric acid, and coumaric acid in various proportions. The physical properties of the plastic are controlled by the composition of the polymers. A melt polycondensation route achieves the desired plastics.

A process for reducing diethylene glycol formation in polyethylene terephthalate includes (a) subjecting a mixture of bis(2-hydroxyethyl)terephthalate with aromatic polycarboxylic acid to an esterification reaction, and (b) subjecting the esterification reaction product to polycondensation.

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.