Clear High-Gloss 2K Polyurethane Topcoat WB

This is a high-performance, water-based two-component polyurethane (PU) clear coat designed for automotive applications. It consists of two components that are mixed before application to form a durable, protective finish with excellent chemical and weather resistance. The formulation is based on Bayhydrol A 145 and Bayhydur 304, providing a clear, glossy finish with low VOC emissions.

Components and Formulation:

Component 1:

• Bayhydrol A 145, 46% (Covestro): Primary resin providing the film-forming base.
• Surfynol 104 BC (Air Products): Wetting agent to improve surface wetting and reduce surface tension.
• Borchi® Gel PW 25 / Borchi® Gel 0621 (Milliken): Rheology modifiers used for controlling viscosity.
• Borchi® Gol LA 200 / Borchi® Gol LA 50 (Milliken): Flow and leveling agents to enhance surface smoothness.

Component 2:

• Bayhydur 304 (Covestro): Polyisocyanate hardener which reacts with the resin to form a tough, crosslinked film.
• Dipropylene glycol dimethyl ether (Clariant): Co-solvent for improving solubility and film formation.

Thinning:

• Water: Used for adjusting the viscosity and application properties.

Mixing and Application:

Mixing Instructions:

1. Combine Bayhydrol A 145 with Surfynol 104 BC, Borchi® Gel PW 25 or 0621, and Borchi® Gol LA 200 or 50. Stir for 10 minutes at 2000 rpm.
2. Allow the mixture to deaerate for one day before use.

Application Method:

• Spray Equipment: Compressed-air spraying with a 1.3 mm nozzle.
• Spray Technique: Apply one cross-coat, allow 5 minutes for intermediate deaeration, then apply another cross-coat and allow 10 minutes for final deaeration.
• Light Stabilizers: To improve weather stability, add 1% Tinuvin 292 and 2% Tinuvin 1130 (both solid/solid resin) before mixing with component 2.

Technical Properties:

Mixing Ratio:

• NCO:OH ratio of 1.5
• Component 1 to Component 2 ratio of 2.7:1

Viscosity and Density:

• Flow Time (DIN 53211-cup 4 mm at 23 °C): 25 seconds
• Cosolvent Content: 9.2%
• Density: 1.0 kg/l
• VOC Content: 194 g/l
• pH Value: 7.7
• Solids Content on Application: 38%

Drying and Hardness:

• Drying Time: 30 minutes at 60 °C
• Pendulum Hardness (DIN EN ISO 1522): 123 s after 1 day at room temperature, 174 s after 7 days, 169 s after 16 hours at 50 °C

Gloss and Haze:

• Gloss (20° angle): 84
• Haze: 24

Chemical Resistance:

• Tested on car body panel with conventional two-pack PU primer and basecoat.
• Resistance to Water, Premium Gas, MPA, and Xylene: Rated on a scale from 0 (no visible changes) to 5 (strongly changed or destroyed surface).
• Alkaline and Acid Cleaning Agents: 7 days at room temperature, rated 0 (no visible changes).

Supplier Information:

• Covestro: Supplier of Bayhydrol A 145 and Bayhydur 304.
• Air Products: Supplier of Surfynol 104 BC.
• Milliken: Supplier of Borchi® Gel PW 25, Borchi® Gel 0621, Borchi® Gol LA 200, and Borchi® Gol LA 50.
• Clariant: Supplier of Dipropylene glycol DME.

Notes:

• This formulation is provided for reference and guidance. Users should test and ensure its suitability for their specific applications.
• All sales are subject to the supplier's standard terms and conditions.

This aqueous two-pack PU clear coat formulation is designed for automotive applications requiring high durability, chemical resistance, and low VOC emissions, ensuring a glossy and protective finish.