Polyethylene terephthalate (PET) grades carrying 30%, 50%, and 100% recycled content with food approval are produced through mechanical recycling sequences that combine near-infrared flake sorting, hot alkaline washing, vacuum decontamination, and in-line melt filtration. The food-contact designation does not rest on the blend ratio alone; each production line must demonstrate that post-consumer PET flakes are converted into pellets with residual contaminant levels below the exposure thresholds recognized in Commission Regulation (EU) 2022/1616 and FDA 21 CFR 174.5. A 100% rPET grade intended for direct food contact is typically produced from washed super-clean flakes subjected to twin-screw extrusion with vacuum devolatilization at pressures below 30 mbar and melt temperatures between 270°C and 285°C, followed by solid-state polycondensation to raise intrinsic viscosity to a minimum of 0.70 dL/g when measured under ASTM D4603. The 30% and 50% grades are generally compounded from the same food-approved rPET pellet diluted with virgin PET at the converter’s own feeding system, though some resin suppliers blend before pelletizing to improve lot-to-lot consistency.

What Decontamination Data Separate Food-Approved rPET from Non-Food Recyclate?

Food-contact approval for recycled PET is process-specific rather than material-generic. Under Commission Regulation (EU) 2022/1616, recycling processes must demonstrate a suitable decontamination efficiency using a challenge test with surrogate contaminants selected to cover volatile polar, volatile non-polar, non-volatile polar, and non-volatile non-polar substances. The resulting cleaning efficiency is evaluated against the migration limits in Annex I of Commission Regulation (EU) No 10/2011, where the overall migration limit is 10 mg/dm² or 60 mg/kg depending on the food-contact surface-to-volume ratio. In the United States, FDA 21 CFR 174.5 permits post-consumer recycled plastics for food contact when the feedstock is controlled and the recycling process yields a suitable purity, generally documented through a Letter of No Objection. Published challenge-test results for food-approved rPET lines frequently show residual surrogates below 0.1 μg/kg in the finished article, but this value is process-specific and cannot be transferred between lines without validation. Processors using 30% or 50% rPET should therefore request the food-approval letter or EU novel technology clearance from the pellet supplier, because dilution with virgin PET reduces contaminant concentration only if the rPET itself already meets food-contact purity.

On a production-scale injection molding line equipped with a hot-runner preform mold, substitution of virgin PET by a 30% rPET food-approved grade requires no fundamental screw redesign but does require tighter control of residual moisture and melt residence time. The incoming rPET pellets should be dried at 160°C to 170°C with a dew point below -40°C until the moisture content falls below 50 ppm, because hydrolytic chain scission during plastication can reduce intrinsic viscosity by 0.02 dL/g to 0.05 dL/g per heat history on a 40:1 L/D reciprocating screw. Barrel temperatures are commonly held at 270°C to 280°C, with the nozzle temperature not exceeding 285°C to limit acetaldehyde regeneration. Acetaldehyde re-formation is more sensitive to residence time than to rPET content at this dilution level. A 30% rPET preform can typically meet the 1.0 ppm residual acetaldehyde threshold for water bottling when measured by ASTM F2013, provided the screw speed and back pressure are not increased beyond the settings used for virgin PET. The main production-scale bottleneck is not melt strength but intermittent filter blockage from low-level flake fines; automatic melt screen changers with 40 μm to 60 μm filtration elements are usually sufficient.

When 100% rPET Is Processed on a 48:1 L/D Twin-Screw Sheet Extruder

Under this configuration, the process window narrows because the full thermal history of the recycled polymer is concentrated into a single conversion step. A 48:1 L/D twin-screw extruder with vacuum devolatilization at 15 mbar to 25 mbar is specified for 100% rPET sheet production, because the residence time distribution is longer than in injection molding and residual aldehydes must be stripped. Melt temperature at the die is usually limited to 275°C to 280°C. At temperatures above 285°C, intrinsic viscosity loss can exceed 0.03 dL/g per pass, and the melt can generate acetaldehyde faster than vacuum devolatilization can remove it. The extruder should be configured with atmospheric and vacuum venting downstream of a melt seal, because the vacuum port must avoid foaming and resin pullover. Melt filtration for 100% rPET food-grade sheet commonly uses a duplex filter with 40 μm to 50 μm screens; pressure differential across the screen pack should be recorded continuously, with a changeover trigger of 80 bar to 120 bar depending on extruder size. Production-scale failures in 100% rPET sheet are most often associated with gel formation from degraded flakes, screw wear from residual metal contaminants, and inconsistent intrinsic viscosity in the incoming super-clean flake. Material certified as food-approved does not automatically guarantee stable sheet gauge; converters should monitor melt pressure variation below ±3% and die lip temperature uniformity within ±2°C.

In stretch blow molding, 50% rPET pellets enter the same reheat and blowing sequence as virgin bottle resin, but infrared absorption differs because the recycled fraction carries a wider distribution of chain length and crystallinity history. Preforms molded from 50% rPET food-approved grades typically require reheat temperatures 2°C to 4°C higher than virgin PET preforms to compensate for reduced intrinsic viscosity and faster stress relaxation. The preform wall thickness may need adjustment at the gate and transition zones if the material exhibits batch-to-batch variation in intrinsic viscosity exceeding 0.02 dL/g. Bottle sidewall haze is generally higher than virgin PET; for a 50% rPET bottle, haze measured under ASTM D1003 on a 1.0 mm wall sample may fall between 2% and 6%, depending on preform design and stretch ratio. This is often acceptable for non-carbonated beverages but may require design review for sparkling water or clear juice. Food approval documentation must still align with the filled product’s simulant and storage conditions; the fact that the bottle contains 50% rPET does not remove the need for compliance testing under the relevant national or EU legislation.

Intrinsic Viscosity, Melt Viscosity and Crystallinity Data Across Recycled-Content Grades

Suppliers of food-approved rPET pellet typically report intrinsic viscosity under ASTM D4603 and melt flow rate under ISO 1133-1:2022. The property window narrows as recycled content increases because the incoming flake mixture contains bottle-grade PET from multiple converters. For a systematic comparison, the following ranges reflect indicative datasheet values for 30%, 50%, and 100% rPET food-contact injection-grade resins. The values are not universal; they depend on flake source, solid-state polycondensation time, and additive package. Processors should verify the exact ranges with the supplier’s certificate of analysis.

Solid-State Polycondensation Is Not Optional for High rPET Content

Without solid-state polycondensation, post-consumer PET flake rarely retains bottle-grade intrinsic viscosity after washing and melt extrusion. Food-approved 100% rPET is therefore processed at temperatures between 190°C and 210°C under vacuum or dry nitrogen for sufficient time to raise intrinsic viscosity into the 0.72 dL/g to 0.78 dL/g bracket. The solid-state reactor must remove residual moisture and acetaldehyde while advancing solid-phase chain extension. In production-scale units, batch time is commonly 12 h to 20 h, depending on pellet size, crystallinity, and target viscosity. Attempts to bypass solid-state polycondensation and rely on chain extenders in food-contact 100% rPET are constrained by the need for food-contact clearance of each additive under EU 10/2011 Annex I or FDA 21 CFR 177.1630. Some chain extenders may not have clearance for direct food contact, and their residual amines can increase acetaldehyde regeneration or modify migration behavior. Converters should therefore not introduce amine-based melt strengtheners into food-approved rPET without a positive migration review for the final article.

A compliance dossier for 30%, 50%, or 100% rPET food-contact grades should include the pellet supplier’s EU declaration of compliance under Commission Regulation (EU) No 10/2011, the relevant EFSA opinion or FDA Letter of No Objection, batch certificates for intrinsic viscosity and residual acetaldehyde, and migration test reports if the final packaging shape differs significantly from the standard migration test specimen. The table below summarizes the main regulatory anchors that a converter should verify before using the material in food packaging.

Lot-to-lot variation in food-approved rPET remains the dominant operational risk. A converter receiving 100% rPET pellets from different flake sources may observe intrinsic viscosity swings of 0.04 dL/g or more, even when every lot is food-approved. The compounding line should therefore be equipped with in-line melt pressure sensors and automatic melt filtration, while the quality laboratory should perform intrinsic viscosity, residual moisture, and acetaldehyde release tests on the first dry batch of each shipment. If the measured intrinsic viscosity falls below the release limit, the material should not be blended with virgin PET to compensate without a written variation from the packaging specification, because downgrading viscosity can reduce bottle top-load strength and increase stress cracking in carbonated soft-drink applications. Pre-drying is mandatory in high-humidity plants above 60% relative humidity, and open storage of rPET pellets should not exceed 24 h after drying.