Waterborne Polyurethane Topcoat
Waterborne Polyurethane Topcoat
I. Product Description
This product is a two-component waterborne coating composed of a water-based hydroxyacrylic emulsion, high-quality pigments and fillers, additives, and a waterborne isocyanate curing agent. It features low volatile organic compound (VOC) content and offers excellent decorative performance and weather resistance.
II. Recommended Uses
Primarily used for corrosion protection and aesthetic decoration in moderate industrial corrosive environments, such as steel structures, mechanical equipment, vehicles, buildings, pipelines, guardrails, and more. Recommended for use as a topcoat in applications involving modified vehicles and construction machinery.
III. Physical Parameters
Color: To be agreed upon
Gloss: Shiny or as agreed.
Solid content by volume: 42 ± 2% (varies depending on color)
Gloss: Shiny or as agreed.
Solid content by volume: 42 ± 2% (varies depending on color)
| Drying time | Coating time | |||
|---|---|---|---|---|
| Temperature | Surface dry | Hard work | Minimum | Maximum |
| 25℃ | 60 minutes | 24 hours | 4 hours | 6 months |
The above data were measured under conditions of a dry film thickness of 50 microns and a relative humidity of 40–60%. Higher coating film thickness, insufficient ventilation, high humidity, or lower temperatures will all extend the curing time.
4. Film Thickness and Coating Rate
Dry film thickness: 30–50 microns
Theoretical coating rate: 7 m²/kg, 8.4 m²/L at 50 μm
Actual coating rate: Allow for an appropriate loss factor.
Theoretical coating rate: 7 m²/kg, 8.4 m²/L at 50 μm
Actual coating rate: Allow for an appropriate loss factor.
V. Construction Reference
Mixing ratio: Component A (base material) : Component B (hardener) = 6:1 (glossy) / 7:1 (matte) (refer to the product packaging label for specific ratios).
Air spraying: Recommended, nozzle diameter 1.0–1.5 mm
Airless spraying: Recommended nozzle diameter: 0.27–0.38 mm; filter mesh size: 120 mesh.
Brush application: Suitable for pre-coating and small-area repairs.
Roller application: Suitable for small-area repairs; using a short-nap roller can achieve a better finish.
Diluent: Clean tap water (add after thoroughly mixing components A and B)
Dilution ratio: For airless spraying, brush coating, or roller coating: 0–5%; for air spraying: 5–10%.
Shelf life: 3 hours at 25℃, shortening as temperature increases.
Equipment Cleaning: Immediately after use, clean the equipment with clean water. It is also recommended to periodically flush the spraying equipment during the construction process.
Work stoppage: Do not leave paint in the paint tube, spray gun, or spraying equipment. Thoroughly rinse the equipment with clean water.
Air spraying: Recommended, nozzle diameter 1.0–1.5 mm
Airless spraying: Recommended nozzle diameter: 0.27–0.38 mm; filter mesh size: 120 mesh.
Brush application: Suitable for pre-coating and small-area repairs.
Roller application: Suitable for small-area repairs; using a short-nap roller can achieve a better finish.
Diluent: Clean tap water (add after thoroughly mixing components A and B)
Dilution ratio: For airless spraying, brush coating, or roller coating: 0–5%; for air spraying: 5–10%.
Shelf life: 3 hours at 25℃, shortening as temperature increases.
Equipment Cleaning: Immediately after use, clean the equipment with clean water. It is also recommended to periodically flush the spraying equipment during the construction process.
Work stoppage: Do not leave paint in the paint tube, spray gun, or spraying equipment. Thoroughly rinse the equipment with clean water.
6. Surface Treatment
Oil and grease shall be solvent-cleaned according to the SSPC-SP1 standard, sandblasted to Sa2.5 grade or derusted with power tools to St3 grade, achieving a surface roughness of 40–70 microns, and ensuring the surface remains clean and dry.
Due to the nature of water-based coatings, they tend to flow away from sharp edges and corners, creating a “corner effect.” To protect these edges and corners from corrosion, it’s necessary to smooth them down and apply a primer coat beforehand.
Before construction begins, all surfaces must be assessed and prepared in accordance with ISO 8504. When applying water-based coatings, it is crucial to strictly adhere to all cleanliness standards.
VII. Precautions
During construction and drying, the ambient temperature should ideally be above 10℃ with relative humidity below 80%. The substrate temperature should be higher than the dew point.
Maintain a temperature above 3℃ and ensure good ventilation. Avoid outdoor construction at night when temperatures are low, especially during seasons with condensation or rainfall.
Maintain a temperature above 3℃ and ensure good ventilation. Avoid outdoor construction at night when temperatures are low, especially during seasons with condensation or rainfall.
Primer coat: Water-based epoxy zinc-rich primer, water-based epoxy primer, etc., can be selected; it can also be applied over solvent-based coatings, but compatibility testing is required. For specific matching recommendations, please consult Holy Hong’s technical sales engineers.
The durability of water-based paints largely depends on proper application. For instance, sharp edges, rivets, and areas with spot welding require extra care during application to avoid excessively thick paint films with each coat; it’s best to apply an additional touch-up coat.
Preparation and Cleaning Steps for Construction Equipment:
To prevent water-based coatings from being contaminated by solvents, the spraying equipment must be thoroughly cleaned before use. All equipment that comes into contact with solvents—such as pumps, pipes, and guns—must be completely cleaned according to the steps outlined below:
Before spraying: Circulate and flush the equipment and pipelines with the original solvent-based paint thinner, then use Holy Hong No. 1 thinner, and finally rinse with clean freshwater.
To prevent water-based coatings from being contaminated by solvents, the spraying equipment must be thoroughly cleaned before use. All equipment that comes into contact with solvents—such as pumps, pipes, and guns—must be completely cleaned according to the steps outlined below:
Before spraying: Circulate and flush the equipment and pipelines with the original solvent-based paint thinner, then use Holy Hong No. 1 thinner, and finally rinse with clean freshwater.
If the construction equipment is made of stainless steel and is specifically designed for applying water-based coatings, this preparation and cleaning work is not required.
8. Storage and Warranty
During storage and transportation, always take care to protect the product from freezing. The recommended storage temperature is between 4°C and 25°C. Store in a sealed container in a cool place, with a shelf life of 12 months.
9. Health and Safety:
Since the paint liquid is not harmless, effective measures should still be taken to prevent skin and eye contact with the coating (such as wearing work clothes, gloves, goggles, face masks, and protective oils). If the product accidentally comes into contact with the skin, thoroughly wash it off with warm water and soap or an appropriate industrial cleaner. If the eyes are contaminated, rinse them with clean water for at least 10 minutes and seek medical attention immediately. It is recommended to wear a ventilated face mask to avoid inhaling paint mist and harmful volatile substances, especially when working in poorly ventilated environments. Disposal of paint waste must comply with national and local disposal regulations.
Statement:
The above information and data are based on laboratory tests and practical experience. Due to individual circumstances (such as construction techniques, testing methods, or improvements in coatings), the data may vary. We reserve the right to modify this instruction manual without prior notice.
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