Abstract: The present invention provides a method for preparing polypropylene terephthalate/polyethylene terephthalate (PPT/PET) copolyester, which comprises a group of processes from (a) to (e). Process (a) comprises subjecting bis-2-hydroxyethyl terephthalate (BHET), pure terephthalic acid (PTA) and 1,3-propanediol (1,3-PDO) to undergo esterification reaction to produce BHET and bis-2-hydroxypropyl terephthalate (BHPT), and then subjecting BHET and BHPT to undergo copolymerization reaction. Process (b) comprises subjecting PTA and 1,3-PDO to undergo esterification reaction to produce BHPT, adding BHET, and then subjecting BHET and BHPT to undergo copolymerization reaction. Process (c) comprises subjecting BHET and BEPT to undergo copolymerization reaction. Process (d) comprises subjecting PTA, ethylene glycol (EG) and 1,3-PDO to undergo esterification reaction to produce BHET and BHPT, and then subjecting BHET and BHPT to undergo copolymerization reaction.

Abstract: The present invention provides a polyester fiber of easy dyeability. The propylene chain of polypropylene terephthalte (PPT) of easy dyeability is incorporated into the main chain of polyethylene terephthalate (PET), and a PPT/PET copolyester having both ethylene and propylene groups can thus be formed. The PPT/PET copolyester is then spun into a copolyester fiber. The copolyester fiber of the present invention can be successfully dyed with a disperse dye at a temperature below 100° C. in the absence of a dye carrier.

Abstract: The present invention provides a novel poly(1,3-propylene terephthalate), which is prepared from reacting terephthalic acid and 1,3-propanediol in the presence of an effective catalytic amount of ethylene glycol titanate to undergo esterification to form a monomer; and polymerizing the monomer in the presence of an effective catalytic amount of antimony acetate to obtain poly(1,3-propylene terephthalate). The obtained poly(1,3-propylene terephthalate) (PPT) has an intrinsic viscosity (IV) of 0.65-0.91 dl/g, acid number (--COOH amount) of less than 40 meq/kg, and L*>60. Without adding a pigment, the yellowness b* of PPT is below 9, even below 5. The yellowness b* of PPT even reaches below 3 when a pigment is incorporated.

Abstract: The present invention is directed to C.sub.60 diamine adducts, processes for preparing them and polymers prepared from them. C.sub.60 diamine adducts is a symmetrical icosahegron which is composed of 12 pentagons and 20 hexagons and links to 2 to 4 diamines. The processes for preparing the product comprises the steps of: adding C.sub.60 in benzene or toluene of a constant concentration to a certain amount of linear aliphatic diamine having the structural formula H.sub.2 N--(CH.sub.2)n--NH.sub.2 wherein n=2, 4 or 6 for reaction, or adding a definite amount of C.sub.60 directly to linear diamine of a definite concentration to produce C.sub.60 diamine adducts. Elemental analysis shows that the product contain about 5.9% nitrogen, about 72.6% carbon and about 3.84% hydrogen, and the number of diamine linked to C.sub.60 is in the range of 2 to 4. C.sub.60 diamine is useful as a polymerization monomer for the preparation of polyamides or relevant polymers.