In PU coating production, parameters like hardness or gloss are often prioritized. However, another crucial property is frequently overlooked when evaluating long-term performance. That is the gas permeability of Desmophen, a factor that defines the protection level of the coating. Understanding this property helps manufacturers improve coating quality significantly.
WHAT IS GAS PERMEABILITY IN POLYURETHANE SYSTEMS?
Gas permeability describes how gases move through a polymer film. Oxygen, moisture and nitrogen can all pass through the urethane network. In PU coatings, gas penetration creates several negative effects. Oxygen accelerates aging. Moisture causes blistering and reduces adhesion. When the film is not tight, the coating delaminates faster under changing environments. Each polyol shows a different gas-permeation rate. Therefore, selecting a polyol based on this parameter is essential.
MECHANISM THAT HELPS DESMOPHEN REDUCE GAS PERMEATION
Polyol structure and network density
Desmophen has an optimized chain structure that forms a uniform and dense network. When the polymer network has high density, micro-voids are greatly reduced. Gas is forced to move along a more complex pathway instead of penetrating straight through the film. Thanks to this, the gas permeability of Desmophen is lower than many common polyols. The stable structure also helps the PU film maintain tightness under mechanical stress. The film does not stretch too much, so its barrier performance stays consistent over time.
Interaction between Desmophen and isocyanate
When Desmophen reacts with isocyanate, the urethane network forms evenly and remains durable. Urethane bonds create a compact structure. Micro-voids are limited during curing. The film becomes more continuous with fewer micro-gaps. At this point, the gas permeability of Desmophen is maximized. Even under humidity, heat or environmental fluctuations, the barrier performance stays stable.
REAL APPLICATIONS WHEN GAS PERMEABILITY IS OPTIMIZED
Industrial coatings requiring high durability
In industrial systems, coatings face harsh environments. Oxygen, moisture and temperature shifts place constant stress on the film. When the film is tight, blistering and oxidation are significantly reduced. Thanks to the gas permeability of Desmophen, the coating maintains adhesion and tightness for a long period. Tanks, pipelines, metal structures and outdoor equipment all benefit from this property. The coating stays glossy, resists rust and maintains hardness longer.
Interior and exterior wood coatings
Wood is highly sensitive to moisture from the environment. Changing humidity causes expansion and cracking. With a tight PU film, moisture cannot penetrate easily. The gas permeability of Desmophen helps the coating protect wood more effectively. For outdoor use, the film must also resist mold and yellowing. When oxygen penetration is limited, oxidation slows down. The surface keeps its color and gloss better. Furniture, louvers and outdoor decking all gain longer service life.
Plastic coatings and industrial films
Plastic materials have a high thermal expansion rate. When temperature changes, the coating must stretch to adapt. A coating with poor tightness blisters easily, especially at stress points. With Desmophen, the film remains stable through thermal cycles. In component manufacturing, the coating must also maintain color and resist scratches. Limiting gas penetration helps the film stay color-stable under light exposure. This is critical for products requiring high aesthetic quality.
VICHEM – EXCLUSIVE DISTRIBUTOR OF COVESTRO CURING AGENTS AND POLYOLS IN VIETNAM
Vichem is the exclusive distributor of Desmodur, Desmophen, Uralac and other Covestro products in the Vietnamese market. We not only supply high-quality materials but also offer international-standard after-sales services.
- Technical consulting: Supporting customers in selecting suitable products for their intended applications.
- Color-matching tests: Vichem specialists perform color-matching evaluations to ensure results meet design requirements.
- Application support: Assisting customers during production integration to ensure optimal efficiency.
For more information, please contact us through:
📞 Hotline: 08 1790 1790
📧 Email: contact@vichem.vn
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