Polycarbonate (PC) brand ownership is distributed among Covestro, SABIC, Teijin, and Mitsubishi; mapping commercial resin families to these owner entities is a prerequisite for traceability, regulatory documentation, and interchangeability assessments. The phrase “Covestro, SABIC, Teijin, Mitsubishi: Mapping Polycarbonate Brands to Owners” describes a supplier-audit exercise in which the designations Makrolon, Lexan, Panlite, and Iupilon are assigned to their respective legal entities. The generic polymer is based on bisphenol A-derived carbonate repeat units and has a density of 1.20 g/cm³ per ISO 1183-1:2019, a tensile modulus of 2300–2400 MPa per ISO 527-2, and a notched Izod impact strength that can exceed 30 kJ/m² per ISO 180/A for unmodified grades.

Covestro AG operates the Makrolon brand and associated copolycarbonate Apec and PC/ABS Bayblend lines. The portfolio transferred from Bayer MaterialScience during the 2015 divestiture. SABIC retains the Lexan brand, including Lexan sheet and Cycoloy PC/ABS, through the 2007 acquisition of GE Plastics. Teijin Limited markets Panlite and Multilon through its Teijin Chemicals integration. Mitsubishi Chemical Corporation markets Iupilon through its engineering-plastics operation. The ownership mapping is stable across current regulatory filings, but grade-specific manufacturing site, stabilizer package, and conversion route may differ within each brand family.

What Links Melt Flow Rate, Moisture Uptake, and Brand Equivalence?

Melt flow rate is the dominant viscosity-classification parameter for PC and is conventionally measured at 300 °C under a 1.2 kg load according to ISO 1133-1:2022. Unmodified medium-flow injection grades typically exhibit melt flow rate values of 10–15 g/10 min; high-flow grades span 20–70 g/10 min, while low-flow extrusion grades remain below 8 g/10 min. Higher melt flow rate values indicate lower average molecular weight and lower melt viscosity, but also reduced notched Izod impact values for a given thickness due to reduced chain entanglement.

Moisture uptake covaries with storage environment and additive package. PC pellets can equilibrate to 0.15–0.35 wt% moisture under humid exposure; the maximum process-safe feed moisture is 0.02 wt%. Above that threshold hydrolysis of carbonate linkages reduces molecular weight and produces surface splay, silver streaking, and embrittlement. A closed desiccant hopper dryer with a dew point of ≤ −40 °C and a setpoint of 120 °C for 3–4 h is standard. At ambient relative humidity above 60%, drying time is extended and hopper-to-press transfer is maintained under dried-air purge to prevent moisture re-uptake.

Brand equivalence cannot be assumed from equal melt flow rate. Makrolon, Lexan, Panlite, and Iupilon grades may be produced by interfacial phosgenation or by carbonate transesterification, and each producer applies separate heat stabilizers, UV packages, mold-release additives, and colorant carriers. Datasheet comparison therefore requires normalization of specimen geometry, conditioning atmosphere per ISO 291, and test speed before interchangeability is claimed.

Optical, electrical, and medical grade selection begins with the same polymer backbone but diverges in additive chemistry. Unfilled high-clarity PC grades transmit approximately 89–90% visible light at 3 mm thickness as measured per ASTM D1003; haze is generally below 1–2% for optical grades. The optical result is sensitive to mold polish, thermal history, moisture, and pigment load. For electrical applications, flame-retarded grades are classified under UL 94; a common target is V-0 at 0.8–3.0 mm thickness, but the relative tracking index under IEC 60112 differs by flame-retardant type. For medical components, selected grades are evaluated under ISO 10993-1:2018 and the biological reactivity requirements of USP <87> and USP <88>. Steam autoclave sterilization at 121 °C is limited for unmodified PC because repeated cycles can induce hydrolysis and molecular weight loss. Radiation sterilization at 25–50 kGy may produce color shift. Substitution from one owner’s grade to another therefore requires validation data rather than a datasheet comparison.

Thermal Degradation and Hydrolysis Boundaries in PC Conversion

Thermal degradation in PC is governed by melt temperature, residence time, and moisture. Injection molding barrel profiles are commonly set between 270 °C and 320 °C, with the nozzle held in the upper region. Screw L/D ratios of 18:1–22:1 and compression ratios of 2.0:1–2.5:1 are specified in supplier conversion guides. Back pressure is normally held at 0.3–0.7 MPa to support homogeneous melt development; excessive back pressure raises shear heating and increases residence time. At melt temperatures above 340–360 °C, or at 300 °C with a residence time exceeding 8–10 min, molecular weight loss and ambering become measurable. Production-scale reciprocating screw machines with dead-end melt channels produce black specks when polymer stagnates and degrades; the failure mode is visible as surface contamination in molded parts and cannot be corrected by retracting the injection unit alone.

The hydrolysis boundary is more abrupt than thermal degradation. At 0.02 wt% feed moisture, hydrolysis of carbonate linkages begins to affect melt viscosity; at 0.05 wt%, splay and molecular weight reduction are severe enough to cause rejection in transparent applications. Drying must be confirmed by dew-point measurement or residual moisture analysis rather than time alone. Dryers should be calibrated to −50 °C dew point or lower when ambient humidity is high or when regrind is used. For sheet extrusion, single-screw equipment with barrel temperatures of 260–300 °C and polish roll temperatures of 100–140 °C is typical; melt filtration is used to remove degraded gel, but filtration does not correct hydrolytic degradation already present in the melt.

Regrind incorporation alters the processing envelope by reducing notched impact and light transmission. The permissible proportion is grade-specific and application-specific; transparent parts usually require a lower regrind fraction than dark-colored structural components. Regrind should be dried as aggressively as virgin resin because compacted regrind can carry more surface moisture and fines. Batch-to-batch variance on production lines is often traceable to dryer dew-point drift, worn screw non-return valves, or hopper throat blockage rather than to base resin variability.

When Are Brand-Specific Datasheet Values Directly Comparable?

Datasheet comparison across Covestro, SABIC, Teijin, and Mitsubishi requires confirmation that values were generated under identical conditions. Tensile data may be reported per ISO 527-2 at 50 mm/min or per ASTM D638-14 Type I; the two methods use different specimen thickness and extensometer practice. Notched impact data may be reported as ISO 180/A notched Izod or ASTM D256; the two methods are not directly convertible. Heat deflection temperature for unfilled PC is typically 125–140 °C at 1.8 MPa per ISO 75-2/A, but a value reported at 0.45 MPa cannot be converted to 1.8 MPa without additional data.

For flame-retarded grades, two competitive products may both achieve UL 94 V-0 at 2.0 mm while differing in relative tracking index, density, and mold deposit behavior. The owner mapping is therefore a documentation starting point, not an engineering equivalence statement. A Makrolon FR grade and a Lexan FR grade may not be interchangeable in an existing mold without verification of gate freeze, shrinkage, and warpage. Shrinkage values for PC are typically 0.5–0.7% in the flow direction and 0.6–0.8% transverse, but specific grades modify these values through fillers, flow modifiers, and pigment systems.

Chemical exposure places further boundaries on brand substitution. PC is incompatible with strong alkalis, ketones, chlorinated hydrocarbons, and aromatic hydrocarbons under tensile stress; environmental stress cracking is evaluated under ISO 22088-2 or ASTM D543. The operational boundary depends on part stress level, temperature, chemical concentration, and contact duration. Data from one brand may not transfer to another if the additive package modifies surface energy or solvent uptake. Transparent applications require control of mold steel corrosion, vent cleanliness, and dried-air handling because these factors generate batch-to-batch consistency effects that are not visible in standardized datasheets.