Zhongtai Petrochemical PTA
- Product Name: Zhongtai Petrochemical PTA
- Factroy Site: Yinchuan, Ningxia, China
- Price Inquiry: sales8@ascent-chem.com
- Manufacturer: Ascent Petrochem Holdings Co., Limited
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- Zhongtai Petrochemical PTA is typically used in formulations when purity, moisture content, particle size distribution, and b-value and esterification temperature, pressure, residence time, and catalyst concentration must be controlled within specific ranges.
| HS Code | 121071 |
| Productname | Zhongtai Petrochemical PTA |
| Chemicalname | Purified Terephthalic Acid |
| Abbreviation | PTA |
| Casregistrynumber | 100-21-0 |
| Einecsnumber | 202-830-0 |
| Molecularformula | C8H6O4 |
| Molecularweight | 166.13 g/mol |
| Appearance | White crystalline powder |
| Purity | ≥99.9% |
| Moisture | ≤0.2% |
| Ash | ≤0.001% |
| 4 Carboxybenzaldehyde | ≤25 ppm |
| P Toluicacid | ≤150 ppm |
| Density | 1.51 g/cm³ |
| Meltingpoint | 402 °C (sublimes) |
| Boilingpoint | 392.4 °C |
| Flashpoint | 260 °C |
| Solubility | Insoluble in water; soluble in dimethylformamide, dimethyl sulfoxide, and alkaline solutions |
| Packaging | 25 kg bags, 500 kg bags, 1000 kg jumbo bags |
| Application | Raw material for polyester fiber, PET resin, and polyester film |
| Storage | Store in a cool, dry, well-ventilated area away from moisture and heat |
As an accredited Zhongtai Petrochemical PTA factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Zhongtai Petrochemical PTA is packaged in 1,000 kg woven jumbo bags with inner liners, suitable for bulk industrial storage and transport. |
| Container Loading (20′ FCL) | Zhongtai Petrochemical PTA is loaded into a 20′ FCL container, typically in 1,000 kg jumbo bags, floor-loaded and securely stowed. |
| Shipping | Zhongtai Petrochemical PTA is shipped as a white crystalline powder in 25 kg woven bags or 1,000 kg jumbo bags, palletized and stretch-wrapped. Transport in clean, dry, covered containers, trucks, railcars, or vessels. Keep away from moisture, heat, ignition sources, and contaminants; follow MSDS and local transport regulations. |
| Storage | Zhongtai Petrochemical PTA should be stored in a cool, dry, well-ventilated warehouse, away from direct sunlight, moisture, ignition sources, and strong oxidizers. Keep bags or containers tightly closed and palletized to prevent dust and contamination. Use grounded equipment, avoid dust accumulation, and follow local fire and safety regulations. Maintain clean handling areas and inspect containers regularly. Store at ambient temperature. |
| Shelf Life | Zhongtai Petrochemical PTA has a 12-month shelf life when stored cool, dry, and sealed, away from moisture, heat, and sunlight. |
In bottle-grade continuous polycondensation, the PTA feed stream governs melt-phase intrinsic viscosity stability through its monofunctional 4-carboxybenzaldehyde content. Slurry paste entering the first esterification reactor is controlled at a molar ratio of PTA to ethylene glycol of 1:1.15; this corresponds to a PTA consumption coefficient of approximately 0.86 kg per 1 kg of melt-phase PET polymer. When 4-CBA exceeds 25 ppm, the aldehyde acts as a chain terminator, suppressing intrinsic viscosity and shifting solid-state polycondensation residence time upward by requiring increased nitrogen flow and elevated polymer bed temperature. Food-contact conformance is reviewed under FDA 21 CFR 177.1630 and EU Regulation 10/2011 with an overall migration limit of 10 mg/dm²; resin for the domestic Chinese market is additionally tested under GB 4806.7-2016. The formulation addition ratio is not a single-point value: slurry solids content is held at 70–72 wt%, antimony trioxide catalyst is dosed at 190–230 ppm Sb, and phosphoric acid thermal stabilizer at 10–40 ppm P to reduce melt-phase degradation.
| PTA parameter | Bottle-grade control range | Process consequence |
|---|---|---|
| 4-CBA | ≤ 25 ppm | Monofunctional chain termination; intrinsic viscosity suppression |
| p-Toluic acid | ≤ 150 ppm | Esterification rate modification; crystallinity shift |
| Moisture | ≤ 0.2 wt% | Slurry packing, hydrolysis, and vacuum load variation |
| b* yellow index | ≤ 0.8 | Visual colour in bottle preforms and recycled flake |
On commercial continuous polycondensation lines, the slurry is pumped through a heat exchanger to the primary esterification reactor at 260–270 °C and 1.2–1.5 bar, then to second-stage esterification at 270–280 °C. Pre-polycondensation is performed at 280–285 °C under 10–20 kPa, followed by finisher at 285–290 °C and 0.1–0.2 kPa. Melt-phase intrinsic viscosity is held at 0.60–0.62 dL/g before pelletizing; after solid-state polycondensation at 205–215 °C under nitrogen, bottle-grade intrinsic viscosity rises to 0.80–0.84 dL/g. Residual acetaldehyde is measured using ASTM F2013-10 and must remain below 8 ppm for still water and 3 ppm for sensitive mineral water. Converted articles include injection-stretch blow-moulded carbonated soft-drink bottles, hot-fill containers, and edible oil bottles.
What Draw Ratio Constraint Arises when 4-CBA Chain Termination Exceeds 25 ppm in Staple Fibre Melt Spinning?
Staple fibre direct melt spinning exhibits a more sensitive response to chain termination than intrinsic viscosity alone because the orientation-induced crystallization plateau shifts when short-chain PET fractions are present. The PTA-to-ethylene glycol molar ratio is maintained at 1:1.12 with titanium dioxide delustrant dispersed at 0.3–0.5 wt% of polymer for semi-dull and full-dull lusters; antimony trioxide catalyst is added at 250–300 ppm Sb and a phosphate stabilizer at 80–120 ppm P. Regulatory review for apparel and nonwoven grades follows EU REACH 1907/2006, OEKO-TEX Standard 100 Class I/II, and ZDHC MRSL V3.4, with antimony and titanium release limits depending on fibre weight. In production, melt at 285–295 °C is delivered to a spinneret with 288–400 holes, and the as-spun filament bundle is hauled at 1200–1800 m/min before drawing at 3.0–3.5:1. Published data for draw ratio limits at 4-CBA levels above 30 ppm is limited, but chain termination is known to reduce tenacity at a given draw ratio because fewer large tie-chain segments form between crystallites. The crimped staple is cut to 32–64 mm for cotton-type spinning or 64–102 mm for woollen-type spinning. Converted staple fibre enters carded sliver for ring-spun yarn, thermal-bonded nonwoven rolled goods, high-loft hollow conjugate filling fibre, and needle-punched automotive interior substrates.
If biaxially oriented PET film is cast on a chilled drum below 25 °C without electrostatic pinning, the cast sheet loses contact at the edges and neck-in destabilizes transverse stretching, producing chatter marks that render the web unsuitable for metallisation. In film-grade PTA supply, the paste molar ratio is set at 1:1.20 PTA to ethylene glycol, while colloidal silica antiblock is metered into the paste at 0.2–0.5 wt% of polymer to prevent winder blocking. Compliance for food packaging is covered by FDA 21 CFR 177.1630 and EU Regulation 10/2011; electronic applications require RoHS 2011/65/EU supplier declarations. The production sequence begins with twin-screw or vented single-screw melt extrusion at 280 °C, cast sheet quenching to 25–35 °C, machine-direction drawing at 3.2–3.6:1 and 80–95 °C, transverse drawing in a tenter frame at 3.8–4.2:1 and 120–140 °C, and heat setting at 220–230 °C with 4–6% relaxation. Slit webs are used in 12 µm flexible packaging film, 188–250 µm solar backsheet core layer, and 2–5 µm capacitor dielectric; capacitor grade requires minimal oligomer deposition and surface roughness Ra below 20 nm.
PBT Melt Stability and Tetrahydrofuran Formation in High-Vacuum Polycondensation
Polybutylene terephthalate synthesis from PTA and 1,4-butanediol is dominated by a side reaction in which 1,4-butanediol cyclises to tetrahydrofuran under acid catalysis, consuming hydroxyl equivalents and shifting the effective PTA-to-diol molar ratio. The feed molar ratio is deliberately run with excess diol at 1:1.30 to 1:1.50 PTA to 1,4-butanediol to compensate for THF loss; tetrabutyl titanate is dosed at 50–150 ppm Ti and a phosphate stabilizer at 0.02–0.1 wt%. Melt-phase esterification proceeds at 220–240 °C under atmospheric or slight vacuum, but the polycondensation stage requires a high-vacuum thin-film reactor at 245–255 °C and 0.5–1.5 mbar to reach a number-average molecular weight suitable for injection moulding. At low vacuum above 5 mbar, terminal hydroxyl groups remain excessive and hydrolytic stability drops. Injection moulding of pellets requires pre-drying at 120 °C for 4 h to a moisture content below 0.02 wt%; failure to do so produces melt viscosity loss, silver streaking and screw torque variation on machines with clamp force between 50 and 350 t. Compliance for electrical and electronic applications is anchored to UL 94 flammability ratings, ASTM D638-14 or ISO 527-2 tensile test, IEC 60695-2-12 glow-wire ignition, and RoHS 2011/65/EU.
| Polycondensation stage | Pressure range | Temperature range | Observed effect |
|---|---|---|---|
| Esterification | 101 kPa | 220–240 °C | THF formation during acid-catalysed water removal |
| Pre-polycondensation | 20–50 mbar | 235–245 °C | Molecular weight build, free diol removal |
| Final polycondensation | 0.5–1.5 mbar | 245–255 °C | Terminal hydroxyl reduction, melt stability gain |
Compounding of PBT is typically run on a twin-screw extruder with L/D ratio 32:1 and a barrel set point of 240–260 °C; glass fibre reinforcement at 10–30 wt% raises viscosity and demands screw torque modulation to prevent fibre attrition. Moulded parts drawn from this resin class include automotive connector housings, ignition coil bobbins, relay bases, and fibre-optic buffer tubes.
During carboxy-functional polyester resin synthesis for hybrid powder coatings, PTA particle size distribution below 45 µm becomes the controlling variable for acid value drift because undissolved PTA particles survive the esterification hold and appear as free acid sites after flaking. The formulation addition ratio places PTA at 40–50 wt% of total reactor charge, with neopentyl glycol, trimethylolpropane and adipic acid; the PTA is charged to a molten glycol mixture under nitrogen and held at 230–250 °C until the acid value falls to 30–50 mg KOH/g, then vacuum is applied at 20–50 kPa to strip water and drive the acid value to the final target. Compliance for architectural powder coatings is verified against ASTM D3451-16 and ISO 8130-2; appliance-grade systems may be certified to UL 94 when used on electrical enclosures. In production, grindability is controlled by maintaining the softening point of the resin at 95–110 °C and the glass transition temperature at 55–65 °C; these values prevent premature fusion during twin-screw extrusion with a barrel temperature of 90–110 °C. Formulations containing carboxy-functional PTA-based resins are not normally compounded with amine-based additives because acid-base gelation occurs during extrusion. The cured film is formed with 7:93 TGIC-to-resin or 5:95 β-hydroxyalkyl amide-to-resin ratios and baked at 180–200 °C for 10–15 min. Finished powder-coated parts cover architectural aluminium profiles, household appliance side panels, and metal furniture.
When DOTP Neutralisation Leaves Residual Sodium Above 10 ppm in Finished Plasticizer
Crude di-2-ethylhexyl terephthalate production from PTA and 2-ethylhexanol is specified with a residual sodium ceiling because sodium soaps generate haze and increase volume resistivity drift in PVC insulation. The esterification feed uses a molar ratio of 2.2:1 to 2.6:1 2-ethylhexanol to PTA and tetrabutyl titanate catalyst at 0.05–0.2 wt% of PTA; reaction water is removed continuously at 180–230 °C under azeotropic reflux. After esterification, the crude ester is neutralised with 0.2–0.5 wt% sodium carbonate solution, washed with demineralised water, and vacuum-stripped at 200 °C and 1–2 kPa to remove unreacted alcohol. Compliance for non-phthalate plasticizer supply is documented under EU REACH 1907/2006, RoHS 2011/65/EU, and EN 71-3:2019 migration limits for toy applications; the product is not subject to Annex XVII Entry 51 phthalate restrictions because it belongs to the terephthalate ester class. In PVC compounding, the addition ratio is 50–70 phr for flexible insulation and 30–40 phr for semi-rigid sheet. Compounded PVC based on DOTP is converted into 105 °C-rated wire and cable jacketing, resilient vinyl flooring, and medical tubing; the medical tubing grade requires low peroxide number because residual unsaturation in 2-ethylhexanol is a precursor to discolouration.
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- Zhongtai Petrochemical PTA is manufactured under an ISO 9001 quality system and complies with relevant regulatory requirements.
- COA, SDS/MSDS, and related certificates are available upon request. For certificate requests or inquiries, contact: sales8@ascent-chem.com.
Zhongtai Petrochemical PTA: Technical Introduction
Zhongtai Petrochemical PTA is supplied as a purified terephthalic acid powder for melt-phase polyester production. The product designation appears in commercial documentation without an additional numerical polymer-grade code; lot release is based on the polyester-grade specification class in GB/T 32685-2016. The chemical substance is 1,4-benzenedicarboxylic acid, CAS 100-21-0, with molecular weight 166.13 g/mol and theoretical acid number 675 mg KOH/g. Bulk density is normally reported in the 700 kg/m³ to 1,100 kg/m³ range. The powder is handled in bulk rail, bulk truck, and flexible intermediate bulk container systems. Typical certified parameters include purity, 4-carboxybenzaldehyde, p-toluic acid, ash, moisture, CIELAB b*, and particle size distribution. The absence of sub-model codes reflects a single purified monomer strategy: fibre-grade, bottle-grade, and film-grade PET are differentiated downstream by catalyst formulation, comonomer level, and solid-state polymerization conditions rather than by a change in PTA lot identity.
What Happens When Zhongtai Petrochemical PTA Replaces DMT in Continuous Melt Trains?
Continuous PET lines using Zhongtai Petrochemical PTA start with paste preparation, in which solid PTA is mixed with ethylene glycol at a molar ratio typically between 1.05 and 1.20. High-shear inline mixers are used because PTA has low solubility in ethylene glycol at ambient temperature; the resulting suspension is pumped through a series of stirred esterification vessels. The first esterifier is commonly maintained at 240 °C to 260 °C and 0.2 MPa to 0.4 MPa absolute pressure. The reaction C₆H₄(COOH)₂ + 2 C₂H₆O₂ ⇌ C₁₂H₁₄O₆ + 2 H₂O proceeds as a heterogeneous liquid-solid process until the PTA dissolves. Water is removed by distillation; if water partial pressure is not controlled, the reverse hydrolysis reaction reduces esterification degree. Typical esterification is terminated at 91 % to 95 % acid conversion, and the resulting bis(2-hydroxyethyl) terephthalate oligomer mixture is transferred to pre-polycondensation and finishing reactors. Melt polycondensation is carried out at 280 °C to 290 °C under vacuum below 50 Pa; antimony trioxide is added at 150 mg/kg to 300 mg/kg antimony relative to polymer, often with phosphorus stabilizers at 10 mg/kg to 50 mg/kg phosphorus. Compared with dimethyl terephthalate-based routes, the PTA process releases water instead of methanol, eliminating methanol recovery and reducing handling of a flammable solvent; the trade-off is a more demanding slurry pumping system and sensitivity of paste rheology to particle size distribution.
On production-scale continuous lines, the main batch-to-batch observation is not purity variation but powder flow and slurry pump load. When laser diffraction d50 shifts from 120 µm to 180 µm, paste viscosity at 70 wt% solids can increase sufficiently to require pump speed adjustment or ethylene glycol dilution. Published data for Zhongtai-specific slurry rheology is limited; users should validate d50, span, and flow function during silo qualification. The acceptable d50 window is commonly 100 µm to 150 µm for continuous paste preparation. If the particle size exceeds this window, undissolved PTA can persist into pre-polycondensation and appear as gel-like defects in the final chip.
4-CBA, p-Toluic Acid, and Slurry Rheology Limits
4-Carboxybenzaldehyde is a monofunctional impurity that terminates polyester chain growth because it contains only one carboxyl group available for esterification. In high-purity PTA, 4-carboxybenzaldehyde is controlled to ≤ 25 mg/kg, while p-toluic acid is held below 150 mg/kg; both are measured by capillary electrophoresis according to ASTM D7884-19. Ash content is typically limited to ≤ 15 mg/kg because transition metals such as iron and cobalt act as degradation catalysts and can destabilise the antimony catalyst system. Moisture is controlled below 0.2 wt%; higher moisture shifts esterification stoichiometry because water is a reaction product and its presence reduces net forward rate. Colour is specified as CIELAB b* and is normally limited to ≤ 1.5 for bottle-grade PET qualification.
| Parameter | Method | Typical range |
|---|---|---|
| Purity | GB/T 32685-2016 | ≥ 99.5 % |
| 4-carboxybenzaldehyde | ASTM D7884-19 | ≤ 25 mg/kg |
| p-toluic acid | ASTM D7884-19 | ≤ 150 mg/kg |
| Ash | GB/T 32685-2016 | ≤ 15 mg/kg |
| Moisture | GB/T 32685-2016 | ≤ 0.2 wt% |
| CIELAB b* | GB/T 32685-2016 | ≤ 1.5 |
| Particle size d50 | ISO 13320 | 100 µm to 150 µm |
The particle size d50 is measured by laser diffraction according to ISO 13320. A coarse tail above 250 µm can increase paste settling and line blockages, while a fine tail below 10 µm increases dusting and electrostatic discharge risk. Two lots with the same median particle size can differ in flow behaviour if the span or surface moisture differs. For this reason, silo qualification for Zhongtai Petrochemical PTA should include shear cell measurements and dense-phase conveying tests under the actual plant dew point and transport velocity.
In PBT melt-phase polymerization, Zhongtai Petrochemical PTA is combined with 1,4-butanediol at 220 °C to 250 °C. Titanium catalysts such as tetrabutyl titanate are typically used at 50 mg/kg to 150 mg/kg titanium. In PBT, carboxy end groups are a direct consequence of feedstock purity and esterification completeness; elevated carboxy end groups reduce hydrolytic stability and can increase screw deposit formation during injection moulding. Melt volume-flow rate is measured according to ISO 1133-1:2022 at 250 °C under 2.16 kg. PTA-based PBT production avoids methanol recovery, but feedstock purity remains critical because residual 4-carboxybenzaldehyde can act as a chain stopper and because tetrahydrofuran formation from 1,4-butanediol increases if the esterification temperature is held at the upper end of the window. The same PTA lot used for PET can be used for PBT; no separate PBT-specific PTA model is required in published technical documentation.
Film-grade PET lines impose a different filterability requirement on the same Zhongtai Petrochemical PTA. Melt filtration with 20 µm to 40 µm candle filters is standard on biaxially oriented PET film lines. Low ash and low 4-carboxybenzaldehyde are critical because residual particulates create gels and char in the filtration system and reduce film surface quality. The same polyester-grade specification is used, while film-grade differentiation is achieved with additive formulation, draw ratio, and winding tension; no separate film-grade PTA model is assigned in public technical literature.
When Zhongtai Petrochemical PTA Is Carried Through Solid-State Polycondensation
Bottle-grade PET production extends the PTA-derived melt polymer through solid-state polycondensation. Amorphous chip is crystallized at 170 °C to 190 °C to prevent sticking, then held at 200 °C to 220 °C under nitrogen or vacuum until intrinsic viscosity reaches the bottle range. The influence of Zhongtai Petrochemical PTA on solid-state polycondensation is indirect: residual 4-carboxybenzaldehyde, diethylene glycol, and carboxy end groups in the melt-phase chip change solid-state kinetics and acetaldehyde reformation. Acetaldehyde is measured by headspace gas chromatography; processors set lot-specific limits below water-contact migration thresholds. PET articles produced from this monomer can be evaluated under FDA 21 CFR 177.1630 and Commission Regulation (EU) No 10/2011 for food-contact compliance. The operational boundary is that the PTA feedstock must remain dry and free-flowing; if storage relative humidity exceeds 60 %, surface moisture adsorption can promote caking in dense-phase conveying lines and introduce water into the esterification mass balance. Production lines with cyclonic fines removal upstream of pre-crystallizers reduce pellet surface defects caused by PTA dust carryover.
Feedstock Purity Determines Both DP Control and Colour Stability in Continuous Melt Trains
The difference between Zhongtai Petrochemical PTA and alternative terephthalic acid sources is primarily analytical: purity, 4-carboxybenzaldehyde, and trace metal content. Medium-purity terephthalic acid can contain 4-carboxybenzaldehyde in the 100 mg/kg to 5,000 mg/kg range, which reduces the maximum attainable degree of polymerization and can shift colour. Recycled terephthalic acid streams vary by collection source and may carry metal residues from catalysts, coatings, and additives. The table below summarises these distinctions. Published direct comparisons for Zhongtai Petrochemical PTA against specific lot samples are limited; the table therefore uses general industrial ranges.
| Feedstock | Typical purity | 4-carboxybenzaldehyde | Processing consequence |
|---|---|---|---|
| Purified terephthalic acid | ≥ 99.5 % | ≤ 25 mg/kg | Direct esterification; consistent degree of polymerization control |
| Medium-purity terephthalic acid | 95 % to 99 % | 100 mg/kg to 5,000 mg/kg | Requires purification or acceptance of lower intrinsic viscosity |
| Recycled terephthalic acid stream | variable | variable | Filtration, colour correction, metal management |
The operational consequence is that Zhongtai Petrochemical PTA is qualified for direct esterification without an intermediate purification step. It should not be confused with orthophthalic anhydride, which is used in unsaturated polyester resins and alkyd coatings and has different reactivity, stoichiometry, and approval frameworks. It also differs from crude terephthalic acid, which is the unpurified oxidation product and is unsuitable for direct melt polymerization without hydrogenation or recrystallization.
Handling of Zhongtai Petrochemical PTA requires combustible dust controls under NFPA 652. As an organic powder, it can form explosible dust clouds; the exact Kst and minimum ignition energy values must be obtained from lot-specific explosibility testing because particle size distribution and moisture shift these parameters. Bulk silo installations should include grounding, bonding, and deflagration venting. The powder is incompatible with strong bases in aqueous solution because neutralisation heat may raise local temperature; it should be stored away from oxidizers. Pneumatic conveying should use dry, oil-free air or nitrogen with dew point below -20 °C to prevent moisture uptake and silo wall adhesion. Dust extraction at bag dumping stations should use HEPA filtration. These operational boundaries apply to the product as a purified terephthalic acid; no material-specific exceptions are published for Zhongtai Petrochemical PTA beyond the standard PTA safety profile.
