New Cpetlight Material Enables Hightemperature Packaging Solutions

The food packaging industry faces persistent challenges in balancing temperature resistance, food safety, and recyclability. Swiss additive and masterbatch specialist Sukano and German thermoforming systems manufacturer Illig have jointly developed an innovative solution: CPET-Light, a breakthrough material that combines transparency, high-temperature resistance, and superior recyclability.

As global consensus grows around circular economy principles, recyclability has become a critical metric for plastic packaging sustainability. Polyethylene terephthalate (PET), one of the most recycled plastics worldwide, offers distinct advantages for food packaging applications. The Sukano-Illig collaboration aims to expand PET's potential in microwave heating and hot-fill applications, providing viable alternatives to commonly used but less recyclable materials like polystyrene (PS) and polypropylene (PP).

Current high-temperature packaging solutions typically use opaque crystalline CPET (crystalline polyethylene terephthalate) variants that withstand temperatures up to 220°C. However, for standard microwave heating and hot-fill applications requiring only 100°C resistance, conventional vacuum-thermoformed APET (amorphous polyethylene terephthalate) cups and trays often fall short. This market gap presents an opportunity for more cost-effective solutions.

The CPET-Light material represents a significant advancement in CPET thermoforming technology. The innovation focuses on achieving transparency for microwave and hot-fill applications while dramatically improving production efficiency in thermoforming systems.

Illig developed an optimized thermoforming process that precisely controls the temperature of films pre-nucleated with Sukano masterbatches. Combined with specialized molds, this process enables production of CPET-Light cups at speeds matching traditional CPET output. These cups not only meet microwave and hot-fill requirements but also integrate seamlessly into PET recycling streams, offering sustainable alternatives to single-use PS and PP packaging.

The joint project focused on producing dairy hot-fill cups with sufficient transparency and 100°C temperature resistance. At Illig's technical center, researchers conducted comprehensive testing using an RDM 70K thermoforming machine and single-cavity mold, with comparative testing performed on PP-H (homopolymer polypropylene) and APET samples.

Sukano produced 1.1mm-thick, 240mm-wide transparent and white CPET-Light films for testing. Four material variants were evaluated: PP-H, APET, white CPET-Light, and transparent CPET-Light.

Production efficiency reached 20 cycles per minute for CPET-Light cups, comparable to PP-H and APET output. Researchers prioritized uniform wall thickness distribution to ensure meaningful comparison of optical and mechanical properties.

After 24-hour storage, comprehensive evaluations measured:

• Wall thickness at critical points
• Mold shrinkage rates
• Top-load strength
• Oven temperature resistance
• Hot water temperature resistance
• Transparency levels

Wall thickness measurements showed comparable distribution across materials, except for thinner APET cup bases and tearing in white CPET-Light cup sealing edges. Mold shrinkage rates measured approximately 0.5% for both APET and CPET-Light, consistent with tool design specifications, while PP showed 1.58% shrinkage.

Top-load compression testing revealed that white CPET-Light cups with thinner sealing edges showed earlier deformation and lower maximum compression force (Fmax). APET cups demonstrated similar behavior due to thin base walls. Transparent CPET-Light cups showed significantly higher Fmax values compared to PP cups, attributable to PET's superior Young's modulus (3800 MPa vs PP's 2000 MPa).

In oven resistance testing at 100°C for 30 minutes, APET cups deformed severely while PP cups showed minimal height shrinkage. CPET-Light samples demonstrated improved deformation resistance through optimized mold geometry.

Hot water resistance testing involved filling cups with 95°C water, emptying after one minute, then measuring after 30 minutes. Transparency measurements using ASTM D-1003 standards showed transparent CPET-Light cups with haze values slightly higher than APET but visually comparable to PP cups.

The CPET-Light solution combines Sukano's pre-nucleated films, specialized mold design, advanced thermoforming equipment, and decades of technical expertise to achieve 100°C temperature resistance. PET's excellent barrier properties ensure oil resistance, while the material's food-grade recyclability supports circular economy objectives.

The transparent variant, enabled by Sukano's specialized nucleation masterbatches, presents an attractive alternative to conventional PP cups. With production speeds matching traditional materials and superior environmental credentials, CPET-Light addresses critical sustainability challenges in food packaging.