Showing papers on "Terephthalic acid published in 1998"

Kinetics of hydrolysis of PET powder in nitric acid by a modified shrinking-core model

Abstract: Poly(ethylene terephthalate) (PET) powder from waste bottles was degraded at atmospheric pressure in 7−13 M nitric acid at 70−100 °C for 72 h, to clarify the mechanism of a feed stock recycling process. Terephthalic acid (TPA) and ethylene glycol (EG) were produced by the acid-catalyzed heterogeneous hydrolysis of PET in nitric acid, and the resulting EG was simultaneously oxidized to oxalic acid. The kinetics of the hydrolysis of PET in nitric acid could be explained by a modified shrinking core model of chemical reaction control, in which the effective surface area is proportional to the degree of unreacted PET, (1 − X), affected by the deposition of the product TPA. The apparent rate constant was inversely proportional to particle size and to the concentration of the nitric acid. The activation energy of the reaction was 101.3 kJ/mol.

Kinetics of Hydrolytic Depolymerization of Melt Poly(ethylene terephthalate)

Abstract: The hydrolytic depolymerization of poly(ethylene terephthalate) (PET) was carried out in a stirred batch reactor at 235, 250, and 265 °C above its melting point and under autogenous pressure. The solid products which were mainly composed of terephthalic acid were analyzed by potentiometric titration and elemental analysis. The liquid products which were mainly composed of ethylene glycol and a small amount of its dimer were analyzed by gas chromatrography. A kinetic model consisting of forward and backward reactions for the PET hydrolysis fitted well with the experimental data. Moreover, an autocatalytic mechanism was suggested, which indicates that some of the hydrolytic depolymerization of PET was catalyzed by the carboxyl groups produced during the reaction. The dependence of the rate constant on the reaction temperature was correlated by the Arrhenius plot giving the activation energy of 123 kJ/mol for the PET hydrolysis.

Copolyester binder fibers

Abstract: The invention relates to fibers, particularly binder fibers, made from copolyesters and the copolyesters themselves. The copolyesters of the invention are generally formed from 1,3- or 1,4-cyclohexanedimethanol, ethylene glycol and isophthalic acid or esters thereof and at least one dicarboxylic acid selected from terephthalic acid, naphthalenedicarboxylic acid, 1,3- or 1,4-cyclohexanedicarboxylic acid or esters thereof. Such copolyesters may be formed into a variety of products, especially binder fibers for nonwoven fabrics, textile and industrial yarns, and composites.

Liquid crystalline resin composition

Abstract: PURPOSE: To obtain the subject composition, excellent in thin-wall moldability, mechanical characteristics, heat resistance and dimensional accuracy, especially improved in plane impact strength and sliding properties and suitable as bearing members, etc., by blending a specific liquid crystal polyester with pith-based carbon fiber. CONSTITUTION: The objective composition is obtained by blending (A) 100 pts.wt. liquid crystal polyester composed of units expressed by formula I and the formulas (O-R 1 -O) and (OC-R 2 -CO) or further (O-CH 2 CH 2 -O) (R 1 is formula II, III, etc.; R 2 is formula II, IV, etc.) in which the sum total of the units expressed by the formulas (O-R 1 -O) and (O-CH 2 CH 2 -O) is equimolar with the unit expressed by the formula (OC-R 2 -CO) with (B) 1-200 pts.wt. pitch-based carbon fiber having 3-18μm average fiber diameter and 1-10 3 μm average fiber length. Furthermore, the component (A) is obtained by subjecting, e.g. p-acetoxybenzoic acid and a diacyl compound of an aromatic dihydroxy compound such as 4,4'- diacetoxybiphenyl and an aromatic dicarboxylic acid such as terephthalic acid to the deacetylating polycondensation. COPYRIGHT: (C)1994,JPO&Japio

Production of terephthalic acid

Abstract: An aromatic carboxylic acid such as terephthalic acid is produced by the liquid phase oxidation of a precursor thereof, the oxidation being carried out in such a way that substantially all of the aromatic carboxylic acid produced in the course of the reaction is maintained in solution during the reaction.

Process for the production of polypropylene terephthalate

Abstract: The present invention provides a method of synthesizing polypropylene terephthalate with no more than 5 ppm acrolein and no more than 3 ppm allyl alcohol. The method comprises direct esterification of terephthalic acid with 1,3-propanediol in the presence of 30 to 200 ppm titanium in the form of an inorganic esterification catalyst containing at least 50 mol % TiO 2 precipitate, blocking the esterification catalyst after esterification by adding 10 to 100 ppm phosphorus in the form of a phosphorus-oxygen compound, and then performing precondensation and polycondensation in the presence of 100 to 300 ppm antimony in the form of a conventional antimony polycondensation catalyst and optional conventional coloring agent.

Poly(terephthalic acid diester)-poly(isophthalic acid diester) resin formulations having improved gas barrier properties

Abstract: The invention is directed to improved poly(terephthalic acid diester)-poly(isophthalic acid diester) resins, and in particular to improved polyethylene terephthalate-polyethylene isophthalate resin formulations, the improved formulations containing nucleating and chain-branching agents. The improved formulations of the invention have particular utility in the manufacture of plastic bottles.

Polarized nexafs spectroscopic studies of poly(butylene terephthalate), poly(ethylene terephthalate), and their model compounds

Abstract: Near edge X-ray absorption fine structure (NEXAFS) spectra were obtained using total electron yield detection for poly(butylene terephthalate) (PBT) and poly(ethylene terephthalate) (PET) and their model compounds 4,4‘-biphenyldicarboxylic acid dimethyl ester (PAM), 4,4‘-biphenyldicarboxylic acid (PCA), and terephthalic acid (TPA). The spectra of PBT and PET were interpreted with the comparison of the spectral features of model molecules and the polarized NEXAFS spectra of oriented films of PAM, PCA, and PBT. From the polarization dependence, the peaks previously ascribed to a C 1s → π*(ring) or π*(ring/CO) excitation at 289.8 eV and an O 1s → 3p/Rydberg or → π*(CO) transition at 536.4 eV were reassigned to a C 1s → σ*(O−CHx) transition and an O 1s → σ*(O−CHx) transition, respectively. The present results demonstrate that the polarization dependence of the NEXAFS spectra of oriented small analogous molecules are useful for the assignment of the NEXAFS spectra of polymers.

Study of the Mechanism for Poly(p-phenylene)benzoxazole PolymerizationA Remarkable Reaction Pathway To Make Rigid-Rod Polymers

Abstract: The mechanism of poly(p-phenylenebenzoxazole) formation from terephthalic acid (TA) and diaminodihydroxybenzene dihydrochloride (DADHB) in polyphosphoric acid (PPA) was studied The solubility of TA in PPA with 86% P2O5 content was determined to be 002% at 100 °C and 006% at 140 °C Dissolved TA existed as three species, TA, α-(4-carboxybenzoyl)-ω-hydroxypoly(oxyphosphinico), and α,α‘-[1,4-phenylenebis(carbonyl)]bis[ω-hydroxypoly(oxyphosphinico)] DADHB also reacts with PPA, and DADHB, α-(2,4-diamino-5-hydroxyphenyl)-ω-hydroxypoly(oxyphosphinico), and α,α‘-(4,6-diamino-1,3-phenylene)bis[(ω-hydroxypoly(oxyphosphinico)] were found During the course of polymerization, conversion of DADHB was higher than that of TA NMR, IR, and mass spectroscopy characterization of PBO oligomer and its product with benzoic-carboxy-13C acid suggested both chain ends were capped with DADHB, which is different from oligomers of conventional AA plus BB step-growth polymers An unprecedented polymerization mechanism is propose

Synthesis and properties of UV‐curable waterborne unsaturated polyester for wood coating

Abstract: UV-curable waterborne unsaturated polyesters for wood coatings were prepared. The effects of different polyols and acids on the properties of the UV-curable waterborne unsaturated polyesters were investigated. Several different unsaturated polyester prepolymers were prepared from three different polyols [ethylene glycol (EG), diethylene glycol (DEG), and propylene glycol (PG)] and three different acids [tetrahydrophthalic anhydride (THPAn), terephthalic acid (TPA), and trimellic anhydride (TMAn)]. UV-curable coating materials were formulated from the prepolymers and 2-hydroxy-2-methylphenyolpropane-1-one as a photoinitiator with distilled water as a diluent. Trimethylolpropane diallyl ether was used as an air inhibitor of cure. The dynamic mechanical studies showed the properties of those unsaturated polyesters were well correlated with their glass transition temperature behaviors. It was found that the unsaturated polyester prepared with 60/40 (mol %) TMAn/THPAn and the equimolar mixture of EG, DEG, and PG showed balanced coating properties such as good tensile properties and weatherability, as well as proper viscosity (ca. 2500 cps) when using distilled water as a diluent. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 695–708, 1998

Thermotropic Hyperbranched Polyesters Prepared from 2-[(10-(4-Hydroxyphenoxy)decyl)oxy]terephthalic Acid and 2-[(10-((4`-Hydroxy-1,1`-biphenyl-4-yl)oxy)decyl)oxy]terephthalic Acid

Abstract: Two new thermotropic, liquid crystalline (LC) hyperbranched polyesters with carboxylic acid end groups were synthesized by direct polycondensation of two pseudo AB 2 type monomers, 2-[(10-(4-hydroxyphenoxy)decyl)oxy]terephthalic acid and 2-[(10-((4'-hydroxy-1,1'-biphenyl-4-yl)oxy)decyl)oxy]-terephthalic acid Their LC properties were characterized by DSC and optical microscopy The carboxylic acid groups of the polyesters were converted to the corresponding methyl esters, and their properties were also investigated The number average molar masses of the polymers were 7000 and 15 000, respectively, corresponding to average degrees of polymerization of about 17 and 31 The degrees of branching of the polymers determined by 13 C NMR spectroscopy were 37 ± 10% and 43 ± 10%, respectively The polyesters with the carboxylic acid end groups form the nematic phase above their glass transition temperatures (T g ), whereas their methyl ester counterparts are not liquid crystalline This observation indicates that the formation of hydrogen bonds between the carboxylic acid terminals plays an important role in mesophase formation by the present polyesters All the polymers are amorphous and are soluble in common organic solvents such as THF, DMF, NMP, pyridine, and DMSO The Tg values of the methyl ester polymers are substantially lower than those of the polymers having acid terminals

Polyamide and its composition

Abstract: PROBLEM TO BE SOLVED: To provide a polyamide having excellent toughness, hot water resis tance, chemical resistance, mechanical characteristics, melt stability, light weight, heat resistance, low water absorption, etc., and further having remarkably improved moldability due to a short molding cycle time and the employment of a hot water-heating mold which can be cooled at low temperature, in compari son with semi-aromatic polyamides such as a conventional PA6-T type polyam ide, and to provide a composition containing the polyamide. SOLUTION: This polyamide is produced from a dicarboxylic acid component whose 60-100 mol.% comprises terephthalic acid and a 4-40C aliphatic dicarboxylic acid in a terephthalic acid/4-40C aliphatic dicarboxylic acid weight ratio of 50/50 to 90/10, and a diamine component whose 60-100 mol.% is a 9C aliphatic diamine, and has an intrinsic viscosity [η] of 0.4-3.0 dl/g in concentrated sulfuric acid at 30 deg.C. A polyamide composition is obtained by adding 0.01-10 pts.wt. of a nucleating agent and/or 0.1-200 pts.wt. of a filler to the polyamide. A molded product comprises the polyamide or the polyamide composition.

A novel synthesis of polyesters with pendant hydroxyl groups by polyaddition of bis(oxetane) with dicarboxylic acids catalyzed by quaternary onium salts

Abstract: Polyesters with pendant primary hydroxyl groups were synthesized by polyadditions of bis(oxetane) with dicarboxylic acids. The polyaddition of bis(3-methyl-3-oxetanylmethyl) terephthalate (BOMT) with adipic acid was carried out in hexamethylphosphorictriamide (HMPA) using certain quaternary onium salts as catalysts at 140°C for 12 h to produce the corresponding polyester, and tetraphenylphosphonium bromide (TPPB) showed the highest catalytic activity among quaternary onium salts used. However, the reaction did not occur without the catalyst or with triethylamine under the same conditions. The yield and the molecular weight of soluble polymer increased with increasing reaction temperature, reaction time, catalyst concentration, and monomer concentration. However, insoluble gel products were obtained when the reaction was performed under less than strict reaction conditions. Polyadditions of BOMT with sebacic acid, isophthalic acid, terephthalic acid, and 2,2′-bis(4-carboxylphenyl)hexafluoropropane were also carried out under similar reaction conditions, and corresponding polyesters with pendant primary hydroxyl groups were obtained in good yields.

The kinetics of diethylene glycol formation in the preparation of polyethylene terephthalate

Abstract: For revealing diethylene glycol (DEG) formation in poly(ethylene terephthalate) (PET) synthesis, this research focused on finding the stage most critical for DEG formation. It is found that the esterification stage was the most critical stage for DEG formation during production of PET through the direct esterification process. In addition, the kinetics of the formation of DEG (ether bond), which is mainly produced from hydroxyl end groups of ethylene glycol (EG) and bis-hydroxyethyl terephthalate (BHET) oligomer, was investigated. The results show that the reactivity of BHET-OH functional group is greater than that of EG-OH functional group in the reaction to produce ether bonds. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 3073–3080, 1998

Method to produce aromatic dicarboxylic acids using cobalt and zirconium catalysts

Abstract: A process to produce terephthalic acid is provided, the process including the steps of: providing a feed stream comprising a dialkyl substituted aromatic and in an organic acid solvent: contacting the feed stream with an oxidant, the oxidant containing at least 50% by volume oxygen and at an oxygen partial pressure of at least 1 psia, at a temperature between about 80° C. and about 130° C., in the presence of a catalyst system comprising zirconium and cobalt, wherein the contacting is done in a stirred tank reactor; removing from the stirred tank reactor a vapor stream comprising the organic acid, water vapor and unreacted oxidant; condensing at least a portion of the organic acid and water from the vapor stream; separating at least a portion of the water from the organic acid back to the stirred tank reactor; returning at least a portion of the condensed organic acid back to the stirred tank reactor; continuously recovering from the stirred tank reactor a product comprising a diacid substituted aromatic; isolating solid crystals of diacid substituted aromatic from the reactor product; and recovering from the solid crystals a diacid substituted aromatic having a purity of preferably at least 97% by weight.

Liquid crystalline polyester compositions containing carbon black

Abstract: Disclosed are liquid crystalline polyester molding compositions which are capable of being molded into an article having a thickness of less than 1.5 mm and a flammability classification of 94V-O as determined by the UL-94 20 mm Vertical Burning Test (ASTM D 3801) which are comprised of (i) certain all-aromatic, liquid crystal polyester consisting essentially of terephthalic acid residues, 2,6-naphthalenedicarboxylic acid residues, hydroquinone residues, and p-hydroxybenzoic acid residues; and (ii) about 0.1 to 10 weight percent, based on the total weight of the liquid crystalline polyester molding composition, carbon black. Theses liquid crystalline polyester molding compositions also may contain glass fiber. The disclosed molding compositions are particularly useful for manufacturing circuit boards and electrical connectors for use in various electronic devices.

The cause of the grey discoloration of PET prepared by the use of antimony‐catalysts

Abstract: Heating three antimony catalysts with several glycols and other model compounds in open and sealed vessels with various degrees of oxygen availability was followed by analyses of the volatile products in the head-space and of the nonvolatile products. Bis(hydroxyethylene terephthalate)(Bis-HET) and terephthalic acid (TA) plus ethylene glycol (EG) were separately polymerized to poly(ethylene terephthalate)(PET) and TA plus triethylene glycol (TEG) was polymerized to poly(triethyleneglycol terephthalate) (PTEGT). Analyses of the polymers and of the model compounds revealed that: 1) Free glycols or the glycolate moieties in polyesters degrade upon heating in the presence of oxygen to produce equal amounts of CO and CO 2 . 2) In the presence of Sb(III) species, the CO oxidizes to CO 2 at elevated temperatures with the concomitant reduction of Sb(III) to very fine black particles of the elemental Sb(0). This is the cause for the grey discoloration of PET made with Sb-catalysts. The redox reaction starts at about 200°C and is fully dominant at about 235°C and above. 3) At temperatures lower than ∼200°C, the Sb(III) usually converts to the white Sb 2 O 3 and the CO does not oxidize the CO 2 .

Late addition of supplemental ethylene glycol in the preparation of copolyesters

Abstract: The application is directed to a method for making copolyesters of terephthalic acid and a diol component including ethylene glycol and includes the steps of adding teraphthalic acid and diol to a first esterification reactor and then late addition of supplemental ethylene glycol subsequent to the first esterification reactor but prior to a point where the ethylene glycol partial pressure is reduced below about 300 torr.

Method to produce aromatic carboxylic acids

Abstract: A process to produce for example terephthalic acid is provided, the process including the steps of: providing a feed stream comprising a dialkyl substituted aromatic and an organic acid solvent: contacting the feed stream with a vapour stream, the vapour stream containing at least 50 % by volume oxygen and at an oxygen partial pressure of at least 1 psi, at a temperature between about 80 °C and about 130 °C, in the presence of a catalyst system comprising zirconium and cobalt, wherein the contacting is done in a stirred tank reactor; removing from the stirred tank reactor a vapour stream comprising the organic acid and water: condensing at least a portion of the organic acid and water from the vapour stream; separating at least a portion of the water from the organic acid separated from the vapour stream; returning at least a portion of the condensed organic acid back to the stirred tank reactor; continuously recovering from the stirred tank reactor a reactor product comprising a diacid substituted aromatic; isolating solid crystals of diacid substituted aromatic from the reactor product; and recovering from the solid crystals of diacid substituted aromatic a diacid substituted aromatic having a purity of at least 97 % by weight.

Method and apparatus for preparing purified terephthalic acid and isophthalic acid from mixed xylenes

Abstract: A method and apparatus for preparing purified terephthalic acid and, optionally, isophthalic acid from mixed xylenes. The method of the present invention purifies the oxidation reactor effluent containing a mixture of terephthalic acid and isophthalic acid as well as minor amounts of 4-carboxybenzaldehyde (4-CBA), 3-carboxybenzaldehyde (3-CBA), and toluic acid isomers, to produce purified terephthalic acid and, optionally, purified isophthalic acid in an integrated process.

Poly(1,3-propylene therephthalate)

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.

Polyester resin composition

Abstract: PROBLEM TO BE SOLVED: To provide a polyester resin compsn excellent in low-noise properties by compounding a thermoplastic polyester resin with a polyacetal resin having a specified melt index SOLUTION: A polyalkylene terephthalate copolymer (A-1) or a polyester elastomer (A-2) is used as the thermoplastic polyester resin Copolymer A-1 is obtd from an acid component comprising 95-55mol% terephthalic acid and 5-45mol% other dicarboxylic acid and a diol component such as ethylene glycol, and elastomer A-2 comprises hard segments such as polybutylene terephthalate segments and soft segments such as ester segments formed from a polyoxyalkylene glycol and an acid This polyester resin compsn is prepd by melt kneading and extruding a compsn comprising 90-50wt% above- mentioned thermoplastic polyester resin and 10-50wt% polyacetal resin having a melt index (at a cylinder temp of 190 degC) of 01-30g/10min with a twin-screw extruder

Biaxially oriented polyester film to be laminated on a metal plate and molded

Abstract: A biaxially oriented polyester film to be laminated onto a metal plate and molded, (A) which comprises a copolyester comprising (a) terephthalic acid in an amount of 82 to 100 mol % and 2,6-naphthalenedicarboxylic acid or a combination of 2,6-naphthalenedicarboxylic acid and other dicarboxylic acid in an amount of 0 to 18 mol % of the total of all dicarboxylic acid components and (b) ethylene glycol in an amount of 82 to 100 mol % and cyclohexanedimethanol or a combination of cyclohexanedimethanol and other diol in an amount of 0 to 18 mol % of the total of all diol components, having (c) a glass transition temperature of 78° C. or more and (d) a melting point of 210 to 250° C., and containing (e) porous silica particles with a pore volume of 0.5 to 2.0 ml/g which are agglomerates of primary particles having an average particle diameter of 0.001 to 0.1 μm; and (B) which has the following relationship between the highest peak temperature (Te, °C.) of loss elastic modulus and the glass transition temperature (Tg, °C.): Te−Tg≦30. This film has improved taste-and-flavor retainabilities, particularly taste and flavor retainabilities after a retort treatment, without losing the excellent moldability, heat resistance, impact resistance and retort resistance of a copolyester film.

Polylactic acid composition, production thereof, and molded article prepared therefrom

Abstract: PROBLEM TO BE SOLVED: To obtain a polylactic acid compsn which does not require a posttreatment after polymn, is excellent in heat stability, and does not exhibit the molwt decrease or discoloration in molding by subjecting a lactide of a cyclic dimer of lactic acid (L-siomer and/or D-isomer) alone or together with a polyhydric alcohol, a lactone, etc, to ring-opening polymn in the presence of a polycarboxylic acid SOLUTION: Pref, triacetylacetonatoaluminum in an amt of 03-3 mol% based on a lactide is used as the catalyst for producing polylactic acid, and the use of tin octoate in an amt of 0003-00001 mol% together with the above compd is pref A polycarboxylic acid to be incorporated into polylactic acid is eg oxalic acid, succinic acid, or terephthalic acid, citric acid being esp pref, and the amt of it incorporated is pref 0001-1 wt% of the lactide The polymn is conducted pref at the mp of the resultant polymer or higher but not higher than 200 degC and in an anhydrous atmosphere A copolymer mainly comprising lactic acid can also be used as polylactic acid