Disclosed is a continuous process and device for making polybutylene terephthalate (PBT) resin, particularly high molecular weight PBT resin. Also disclosed are a device for conducting the process, and a monitoring process for determining the carboxylic acid end group concentration of the resulting PBT.

The present invention relates to a method for preparing a bio-based polycarbonate ester, the method comprising the steps of: (1) preparing a compound represented by chemical formula 3 by converting a compound represented by chemical formula 2 into an intermediate reactant having an easily detachable functional group, followed by a nucleophilic reaction with phenol; and (2) preparing a compound including a repeat unit represented by chemical formula 1 by a polycarbonate melt condensation polymerization of the compound represented by chemical formula 3, prepared in step (1), a compound represented by chemical formula 4, and 1,4:3,6-dianhydrohexitol. The bio-based polycarbonate ester according to the present invention can regulate merits and demerits of physical properties obtained from each repeat unit, and can be favorably used for various uses due to high degrees of transparency and heat resistance thereof.

The present invention relates to a method for preparing a bio-based polycarbonate ester, the method comprising the steps of: (1) preparing a compound represented by chemical formula 3 by converting a compound represented by chemical formula 2 into an intermediate reactant having an easily detachable functional group, followed by a nucleophilic reaction with phenol; and (2) preparing a compound including a repeat unit represented by chemical formula 1 by a polycarbonate melt condensation polymerization of the compound represented by chemical formula 3, prepared in step (1), a compound represented by chemical formula 4, and 1,4:3,6-dianhydrohexitol. The bio-based polycarbonate ester according to the present invention can regulate merits and demerits of physical properties obtained from each repeat unit, and can be favorably used for various uses due to high degrees of transparency and heat resistance thereof.

A method for producing an oligomeric PET substrate for use in a rPET manufacturing process comprises reacting recycled bis-hydroxylethyleneterephthalate (rBHET) or a higher molecular weight oligomer derived from rBHET, with PTA to produce an oligomeric PET substrate represented by Formula (I), wherein R.sub.1 is a carboxyl end group or a hydroxyl end group, R.sub.2 is a carboxyl end group or a hydroxyl end group, and n is a degree of polymerisation.

A method for producing an oligomeric polyethylene terephthalate (PET) substrate for use in a recycled PET (rPET) manufacturing process, comprising (i) adding recycled bis-hydroxylethylenete rephthalate (rBHET) and an under-esterified purified terephthalic acid (PTA) oligomer to a reaction zone; and ii) reacting the rBHET and the under-esterified PTA oligomer in the reaction zone to produce an oligomeric PET substrate represented by the formula (I), wherein R1 is a carboxyl end group or a hydroxyl end group, R2 is a carboxyl end group or a hydroxyl end group, and n is a degree of polymerisation (Dp).

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A method for improving L* color of polyethylene terephthalate polymer, the method including bis-hydroxylethyl-eneterephthalate being polycondensed to produce said polyethylene terephthalate polymer in a polyethylene terephthalate manufacturing process, and wherein said process requires an antimony-containing catalyst, the method comprising the steps of: i) adding said antimony-containing catalyst at a temperature in a range of a melting point of said BHET to an upper temperature of 220° C.; and ii) exposing said BHET in a molten state to glycol removal before addition of said antimony-containing catalyst.

The present invention is a method for producing a liquid crystalline polyester, which comprises reacting an aromatic hydroxycarboxylic acid, a diol containing 70 mol % or more of an aromatic diol having a structural unit (I) as shown below and an aromatic dicarboxylic acid with one another in the presence of an acylating agent and an aliphatic sulfonic acid represented by formula (A) shown below. (wherein Ar represents a bivalent aromatic group which is an aromatic hydrocarbon group and has a molecular weight of less than 200) Formula (A) R—SO.sub.3H (wherein R represents an alkyl group having 1 to 12 carbon atoms) According to the present invention, a liquid crystalline polyester, which can be molded into an article having excellent tensile strength and excellent creep properties and from which a gas is generated in a reduced amount, can be produced with high efficiency.

The present invention is a method for producing a liquid crystalline polyester, which comprises reacting an aromatic hydroxycarboxylic acid, a diol containing 70 mol % or more of an aromatic diol having a structural unit (I) as shown below and an aromatic dicarboxylic acid with one another in the presence of an acylating agent and an aliphatic sulfonic acid represented by formula (A) shown below. (wherein Ar represents a bivalent aromatic group which is an aromatic hydrocarbon group and has a molecular weight of less than 200) Formula (A) R—SO.sub.3H (wherein R represents an alkyl group having 1 to 12 carbon atoms) According to the present invention, a liquid crystalline polyester, which can be molded into an article having excellent tensile strength and excellent creep properties and from which a gas is generated in a reduced amount, can be produced with high efficiency.

Provided are methods of producing sulfur- and phosphorus-containing polymers from beta-lactones. The sulfur- and phosphorus-containing polymers include bio-based sulfur- and phosphorus-containing polymers that may be obtained from renewable sources.

The present invention relates to biodegradable copolyesters with molecular weight Mn from 10 000 to 100 000 measured by GPC, obtainable via reaction of i) from 51 to 84% by weight, based on the copolyester, of a branched polyester middle block produced from aliphatic or aliphatic and aromatic dicarboxylic acids and from aliphatic dihydroxy compounds with molecular weight Mn from 5000 to 25 000 measured by .sup.1H NMR with from 15.9 to 48.9% by weight, based on the copolyester, of a lactide in the presence of a catalyst, and then the resultant polyester triblock with molecular weight Mn measured by .sup.1H NMR from 5800 to 49 500 with ii) from 0.1 to 3% by weight, based on the copolyester, of a diisocyanate.

The present invention further relates to a process for the production of, and to the use of, the abovementioned biodegradable copolyesters.