In the production of polyurethane synthetic leather, surface hazing has long been a persistent challenge for manufacturers. This phenomenon, characterized by the appearance of a whitish, fog-like layer caused by small molecular migration, not only affects product appearance but also reduces market competitiveness.
Causes of Surface Haze in Polyurethane Synthetic Leather
1. Raw Material Formulation
Raw material composition plays a critical role in determining the surface quality of polyurethane synthetic leather. Studies show that polypropylene glycol (PPG) soft segment, 1,2-propanediol (1,2-PG) chain extender, and post-chain extension levels of 30% or 90% are key contributors to hazing in waterborne polyurethane (WPU) synthetic leather. Under certain reaction conditions, these components promote migration of low molecular weight substances, resulting in snow-like haze on the surface.
2. Process Parameter Control
Improper control of process parameters is another major cause of hazing. Variations in temperature, humidity, and coating speed during production can significantly impact material behavior and surface performance.
3. Equipment Precision Issues
Equipment precision is fundamental to product quality. In polyurethane synthetic leather production, the accuracy of the metering system, mixing uniformity, and temperature stability directly affect surface performance. Metering deviations may alter the raw material ratio, impacting polymer crosslinking and molecular structure while increasing haze risk. Poor mixing results in localized incomplete reactions, producing easily migrated molecules. Insufficient temperature accuracy causes fluctuations in reaction conditions and affects molecular weight distribution and crosslink density, increasing haze and reducing mechanical properties.
Feilong Polyurethane Equipment Solutions
✅ High-Precision Metering System
Feilong Polyurethane Equipment features a high-precision metering system to ensure accurate raw material ratios. The system uses low-speed precision metering pumps with excellent heat and pressure resistance. With a metering accuracy of up to ±0.5%, composition deviations are minimized to prevent haze caused by formulation errors.
Example: Feilong’s elastomer casting machines precisely control multi-component flow rates to maintain stable chemical ratios and prevent phase separation.
✅ Intelligent Temperature Control Technology
To eliminate haze caused by temperature instability, Feilong equipment is equipped with an intelligent temperature control system. Each material tank, metering pump, and pipeline is controlled independently to ensure stable thermal conditions throughout production.
Example: Feilong’s moldless casting system maintains temperatures precisely between 60–125°C, adapting to different formulations and greatly reducing haze caused by temperature variations.
✅ Multi-Component Ratio Control
For complex polyurethane formulations, Feilong’s multi-component metering system ensures complete and uniform reactions between components.
Example: The fully automatic multi-component medical dressing production line enables precise and consistent composition control, eliminating haze risk caused by incompatible ratios.
✅ Advanced Mixing Technology
Feilong equipment adopts specialized mixing heads designed for continuous and homogeneous material blending.
Example: In Feilong’s automotive filter seal production system, the floating mechanical seal mixing head can operate continuously for hours without overheating or cross-contamination, ensuring full reaction and reducing small molecule migration.
Conclusion
Surface hazing in polyurethane synthetic leather is a complex issue affected by raw material formulation, process parameters, and equipment performance. Feilong Polyurethane Equipment delivers a complete and effective solution through:
✔ High-precision metering
✔ Intelligent temperature control
✔ Multi-component ratio technology
✔ Advanced mixing systems
With over 20 years of expertise in polyurethane machinery, Feilong provides manufacturing solutions that improve production consistency, eliminate haze, and boost product quality. This increases competitiveness while reducing costs—empowering synthetic leather manufacturers in automotive interiors, footwear, furniture, and fashion industries.
Looking ahead, Feilong will continue to innovate smarter, more energy-efficient, and environmentally friendly polyurethane equipment to support the long-term development of the synthetic leather industry.
