[article]
| Titre : |
Quality assurance |
| Type de document : |
texte imprimé |
| Auteurs : |
Andrew Hinks, Auteur |
| Année de publication : |
2002 |
| Article en page(s) : |
p. 23-25 |
| Langues : |
Anglais (eng) |
| Catégories : |
Formulation (Génie chimique)
Peinture -- Teneur en solides
Revêtement en phase solvant:Peinture en phase solvant
Température -- Contrôle
|
| Index. décimale : |
667.9 Revêtements et enduits |
| Résumé : |
The application of a coating to a substrate can, if not carried out correctly, sometimes lead to degradation and corrosion problems. The author looks at ways to overcome these problems.
Even if process raw materials are perfect when they enter a production line, they do not usually stay that way for long. Almost as soon as a coating is put into the day tank, it begins to degrade through evaporation and consequent concentration of solids. This degradation compromises coating quality and can seriously inflate costs. To enable accurate application of a coating to a substrate, the coating manufacturer's specification will quote a temperature range, often using limits of around plus or minus five degrees, and the coating's viscosity for that range. Generally the coating will be supplied at the ideal ratio of solids to solvent, to give the specified viscosity for the process temperature. Running the coating process outside these manufacturer's parameters can result in problems with the final coating quality, or lead to excessive coating use, because the loss of solvent through evaporation allows excess solids to be applied. Despite these potential problems, it has still been known for customers to ask for a coating to be supplied with excess solvent, to allow for evaporation during use. However, even buying a coating at the correct viscosity does not guarantee success. Actively controlling both the coating's temperature and solids content within the manufacturer's specification is key to producing high quality, accurate coatings. Line operators have an immensely difficult task in controlling dry film weight accurately. This is because of a lack of capability in both process management and film measurement. During the process, variations in solids content and coating temperature can be enormous, causing the final dry film weight to vary in a way that appears to be random. |
| Note de contenu : |
- Weight measurement
- Solids ratio
- Maintenance
- Chamber
- Material
- Gauge capability
- FIGURES : 1. Temperature specifications help to ensure the final coating's quality - 2. Sophisticated maths makes it possible to calculate a consistent and true solid/solvent ratio - 3. Repeatability and reproductibility (R&R) needs three typical operators, an item to measure and the R&R formula |
| Permalink : |
https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=28099 |
in POLYMERS PAINT COLOUR JOURNAL - PPCJ > Vol. 192, N° 4450 (03/2002) . - p. 23-25
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