OMNISTAB AN91PQ – Specialty Antioxidant for Anti-Fog and Anti-Yellowing in High-Clarity PC/PET Products

PC and PET are mainstream choices for high-clarity products. PC offers excellent transparency, impact resistance, and heat resistance, making it ideal for tough transparent parts. PET provides high clarity, good gloss, low cost, and easy processing, widely used in transparent packaging and optical substrates. However, both face processing challenges: PC is prone to stress-induced microcrystallization under shear during high-temperature molding, causing haze to spike; PET is sensitive to acid-catalyzed degradation during high-temperature melting, leading to graying and whiteness loss. Conventional antioxidants struggle to address both issues.

OMNISTAB AN91PQ, with its unique biphenyl rigid diphosphite molecular structure, solves these processing defects at the molecular level and is suitable for all types of high-clarity PC and PET products.

For PC: Inhibits Stress Microcrystallization, Maintains High Clarity and Low Haze

PC is an amorphous polymer, but during extrusion, injection molding, and stretching, the melt is subjected to high temperature and shear stress, which can induce local chain alignment and stress-induced microcrystallization. These tiny crystals cause uneven refractive index and light scattering, resulting in increased haze and reduced clarity.

AN91PQ has a planar rigid biphenyl structure with high charge-transfer compatibility with PC’s bisphenol A benzene rings. During processing, it inserts between PC molecular chains, disrupting local ordered packing, inhibiting microcrystal nucleation and growth, and maintaining a fully amorphous, homogeneous state. This stabilizes light transmission and reduces haze. It also offers high heat resistance, low volatility, and low precipitation—no decomposition or blooming during high-temperature processing. Combined with primary antioxidants, it captures hydroperoxides, inhibits melt thermo-oxidative yellowing, stabilizes melt flow, and reduces color differences and surface defects.

Recommended applications: PC optical films, transparent sheets, optical lenses, light guide plates, car lamp covers, transparent housings, modified transparent PC compounds, and all high-clarity PC products.

For PET: No Acidic Intermediates, Prevents Graying and Darkening During High-Temperature Processing

PET resin is highly sensitive to transesterification and acid-catalyzed degradation during high-temperature melt processing. Conventional phosphite antioxidants easily hydrolyze in the presence of trace moisture, releasing free phenols and acidic phosphorus compounds. These acidic substances attack PET chain ends, catalyzing thermal degradation and local carbonization, causing graying, increased haze, and reduced whiteness.

AN91PQ has excellent molecular stability and does not release acidic intermediates that catalyze substrate degradation during high-temperature processing. In PET injection molding, extrusion, and stretching, it efficiently decomposes hydroperoxides and blocks the thermo-oxidative chain without triggering PET acidolysis side reactions. It preserves PET’s original light transmission and whiteness, solving the industry pain point of graying and darkening during high-temperature processing. Its hydrolysis resistance is superior to ordinary phosphites, with less die buildup and cleaner product surfaces.

Recommended applications: PET optical films, transparent sheets, transparent injection-molded parts, transparent food packaging, transparent polyester compounds, and various high-clarity PET products.

Core Highlights of OMNISTAB AN91PQ

• Biphenyl diphosphite with high thermal stability and high decomposition temperature, suitable for PC/PET high-temperature processing windows

• Domestic high-performance alternative with stable supply and optimized formulation cost

• Low volatility and low precipitation, less mold fouling, reduced downtime for cleaning, and improved yield

• Synergistic with phenolic primary antioxidants, balancing processing anti-yellowing and long-term thermal aging protection

• Precisely solves the two core challenges of transparent products: PC stress crystallization fogging and PET high-temperature acidolysis graying

• Wide application range, covering not only films but all high-clarity PC and PET products

Application Summary

• PC: Optical films, transparent sheets, optical lenses, light guide substrates, transparent car lamp parts, transparent electronic housings, transparent PC alloy compounds

• PET: BOPET optical films, transparent PET sheets, transparent PET injection-molded parts, transparent food packaging, high-end transparent polyester modified materials

  
  

OMNISTAB AN91PQ solves the pain points of transparent products at the molecular level. For more information, please contact our sales team.