The present disclosure provides a Lewis acid-base pair catalytic initiator and an application thereof. The Lewis acid-base pair catalytic initiator includes a Lewis acid and a Lewis base, the Lewis acid having a structural general formula as shown in formula (I) and the Lewis base having a structural general formula as shown in formula (II); wherein: the A is selected from element Baron or element Aluminum; the R.sub.1, R.sub.2, R.sub.3, R.sub.4 are independently selected from alkyl, alkoxy, aryl or halogen groups; the alkyl or alkoxy have a carbon number being equal to or greater than 1 to equal to or less than 16; the aryl contains substituents with the number being equal to or less than 5, the substituents being selected from methyl, methoxy or halogen; n is selected from an integer from 1 to 16.

The present invention describes the preparation of heterogeneous catalysts of mixed oxides based upon niobium and mixed oxides of zinc, manganese, nickel, cobalt and/or aluminum, originating from hydrotalcites (HTs) as precursor phase of heterogeneous catalysts, and application thereof in the chemical recycling of poly(ethylene terephthalate) (PET) for the production of metal free bis(hydroxy)ethylene (BHET) monomers and oligomers having a processing performance similar to that of the homogeneous catalysis system.

Compounds can be used as catalysts, particularly in ring-opening polymerization reactions, including ring-opening co-polymerization (ROCOP) reactions, or in isocyanate trimerization reactions. The compounds have the formula L-M-X.sub.n, where L is a pyridyl-bis(iminophenolate) ligand, M is a metal ion, X is a co-ligand to balance the charge of the compound, and n is an integer from 0 to 7. The compounds can be prepared by base condensation of a pyridyl-diamine compound with an aldehyde or ketone.

Compounds can be used as catalysts, particularly in ring-opening polymerization reactions, including ring-opening co-polymerization (ROCOP) reactions, or in isocyanate trimerization reactions. The compounds have the formula L-M-X.sub.n, where L is a pyridyl-bis(iminophenolate) ligand, M is a metal ion, X is a co-ligand to balance the charge of the compound, and n is an integer from 0 to 7. The compounds can be prepared by base condensation of a pyridyl-diamine compound with an aldehyde or ketone.

Provided is a process for producing a product having polyglycolic acid and glycolide from methyl glycolate. The process comprises esterification, polycondensation and optimization. Also provided are a product produced by the process and a method of changing the amount of the polyglycolic acid in the product by modifying the amount of an esterification catalyst and/or adjusting the reaction temperature.

The present invention relates to a production method of a poly(ester)carbonate, including subjecting a diol and a carbonate ester to a transesterification reaction in the presence of a catalyst, wherein the catalyst comprises aluminum or a compound thereof, and a phosphorus compound.

A process is disclosed herein comprising the steps: a) contacting a mixture comprising furandicarboxylic acid dialkyl ester, 1,3-propanediol, a zinc compound, and optionally a poly(alkylene ether) diol, at a temperature in the range of from about 120° C. to about 220° C. to form prepolymer, wherein the mole ratio of the furandicarboxylic acid dialkyl ester to the 1,3-propanediol is in the range of from 1:1.3 to 1:2.2; and b) heating the prepolymer under reduced pressure to a temperature in the range of from about 220° C. to about 260° C. to form polymer. The mixture of step a) can further comprise an anthraquinone compound.

A method for producing polyester resin containing an ethylene terephthalate structural unit of not less than 85 mol%, the method comprising: a melt-polymerization step of continuously performing melt-polymerization in two or more polymerization vessels by using an aluminium compound and a phosphorus compound as a polymerization catalyst; and a solid phase polymerization step of performing solid phase polymerization after the melt-polymerization step, wherein a polymerization in a final polymerization vessel of the melt-polymerization step satisfies a condition represented by the following formula: 410≤T*RT*(P/Al)≤580, wherein T represents a temperature (°C) in the final polymerization vessel, RT represents residence time (hour) in the final polymerization vessel, and P/Al represents a molar ratio of phosphorus element to aluminium element in the polyester resin.

To provide a biaxially-oriented polyester film roll that is excellent in transparency and heat resistance and has less defects. A biaxially oriented polyester film roll of the present invention characterized by satisfying requirements (1) a winding length of the film roll, (2) a width of the film roll, (3) an average hardness of an outermost surface layer of the polyester film roll, (4) a variation in hardness, (5) a thickness of a polyester film of the polyester film roll, and (6) an irregularity of thickness in the maximum concave portion.

The present invention relates to a kind of organic metal-free catalysts containing both electrophilic and nucleophilic dual-functions, preparation methods of making the same, and uses thereof. The organic metal-free catalysts in the present invention have the chemical structure shown in formula (I):

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Compared with the metal-free organic polymerization catalytic systems that have been reported before, the organic metal-free catalysts in this invention have the combined advantages of simple preparation, high reactivity, easy operation, low cost, wide applicability, easy for industrial production.