Pendulum hardness of a 2K PU clearcoat.
The problem
A customer rejects our 2K PU clearcoat because the cured film is too soft. The recipe and the baking process have grown over the years, and nobody can say anymore which settings control hardness. Below are 12 factors, the full recipe and the full process window. Tell me which of them influence hardness and give me the settings that maximize it. The response is König pendulum hardness in seconds, measured after full cure. Higher is better. Only settings inside the ranges are allowed, and the measurements are noisy.
| Column | Factor | Unit | Low, −1 | High, +1 |
|---|---|---|---|---|
| Formulation | ||||
| X01 | NCO:OH index | 0.9 | 1.3 | |
| X02 | Polyol OH number (blend) | mg KOH/g | 140 | 180 |
| X03 | Catalyst (DBTDL) | ppm | 0 | 400 |
| X04 | Flow additive | % | 0.1 | 1.0 |
| X05 | Matting agent | % | 0 | 4 |
| X06 | Solvent dilution | % | 10 | 25 |
| Application | ||||
| X07 | Flash-off time | min | 5 | 20 |
| X10 | Dry film thickness | µm | 30 | 60 |
| X11 | Booth humidity | % r.h. | 30 | 70 |
| X12 | Substrate temperature | °C | 18 | 30 |
| Cure | ||||
| X08 | Cure temperature | °C | 60 | 100 |
| X09 | Cure time | min | 20 | 60 |
How it works
- 01
Plan your runs.
- 02
Run them below.
- 03
Send me your answer.
You can plan and run as many rounds as you need before you send me the final result.
Run your experiments
Send a run sheet
An Excel or CSV file with one column per factor from X01 to
X12, in coded levels or real units.
Saved in this browser. Send this file with your answer.
Send me your answer
I'd really appreciate your contribution. Thank you for taking the time.
Thank you.
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