Reduce Heating & Cooling Costs

Architectural Coatings that Reduce Heating and Cooling Costs

Posted on by chemical dynamics

In order to appreciate architectural coatings that reduce heating and cooling costs, it is important to understand the fundamentals regarding US energy consumption. According to the U.S. Energy Information Service, 40 percent of all US energy consumption is used for heating and cooling residential and commercial buildings. For homeowners, 25 percent of their average energy bill is for cooling. Considering these facts, consumers appreciate any efficiencies coatings formulators can offer.

Heat transfer mechanisms

Prior to considering how coatings can be engineered to save heating and cooling costs, it is instructive to examine heat transfer mechanisms: radiation, conduction, and convection.

Radiation

As figure 1 indicates, radiation is the emission and propagation of light energy in the form of rays or waves through space:

architectural-fig1
Figure 1 – Radiation light spectrum1

As figure 2 illustrates, pigments can absorb or reflect solar infrared energy based on their color.  For example, if the pigment absorbs infrared (IR) energy (such as conventional darker pigments), we see heat build-up of the coated substrate. If the pigment reflects IR light (such as white and lighter colors), we see a lower increase in temperature.

To illustrate, the surface of a steel building at an ambient air temperature of 20° C will remain at about 20° C when painted white, whereas the surface will be about 35° C when painted black.

 

To read the rest of the article please click here to head over to UL Prospector.

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Ron Lewarchik, Author of article & President of Chemical Dynamics

As a contributing writer, Ron pens articles on topics relevant to formulators in the coatings industry. He also serves as a consultant for the Prospector materials search engine, advising on issues related to optimization and organization materials within the database.

Metal Surface Treatment

Metal Surface Treatment – The Key to Successful Performance

Posted on by chemical dynamics

No matter what metal surface needs to be painted, successful performance begins with proper cleaning and surface preparation. This article will concentrate on the essential issues in the manufacturing process necessary to ensure successful metal treatment and resultant coating performance. As there are hundreds of surface treatments, we will address the major factors that influence phosphate metal pretreatment which are one of the most widely used pretreatment chemistries. Phosphate treatments are used on steel, zinc and aluminum substrates.

The pretreatment process for metal surfaces provides multiple benefits as it is the foundation of the paint layering system. A quality metal treatment process enhances adhesion between the metal and paint layers by providing a more uniform surface and provides greater corrosion resistance with less undercutting of the paint film.

Table I – Typical Spray or Immersion Process involved in Phosphate Pretreatment

PROCESS STEP ORDER PURPOSE CHEMICALS POTENTIAL PROBLEM(S)
1. Cleaning (see Figs I & II) Remove soils, mill oil, lubricating oil and drawing compounds, dissolution of metal oxide(s), precipitate hard water deposits Alkaline Cleaner
  1. Incomplete removal, synthetic oils can be more difficult to remove than natural oils
  2. Contaminated cleaning process, cleaning chemicals spent
  3. Temperature too low
  4. Poor tank maintenance
  5. Inadequate mechanical action
  6. Change in time, temperature, pressure (for spray cleaner) or cleaner concentration
2. Water rinse(s) Remove residual detergents and deposits Quality tap water and/or reverse osmosis (R/O) water
  1. Drag out water sensitive deposits from the cleaning process
  2. Tap water that contains hard water may deposit moisture soluble compounds on the metal surface
3. Rinse Conditioner (see Fig III) For Phosphate- Aids in the development of the proper phosphate crystals on the metal surface Colloidal Titanium Salts and additives Destabilization of the Ti Colloid:

  1. pH too low or too high
  2. High heat
  3. Contamination
  4. Poor water quality (too hard)
4. Phosphate Step (See Fig IV) Forms a microcrystalline coating to enhance paint adhesion and corrosion resistance
  1. Phosphoric and nitric acid
  2. Zn, Ni, Mn Fe cations
  3. Fluoride, Surfactants and accelerator
  1. Must continually remove iron phosphate sludge for proper control
  2. Ensure optimum recirculation rate for tank process or spray nozzle pressure for spray process
5. Rinse Stops the chemical reaction on the metal surface Water Water must be clean
6. Post Rinse Fill voids in pretreatment Hexafluorozirconqic acid Proper control of pH, time , temperature and pressure (spray)
7. Deionized (D.I.) Rinse(s) Remove any residual chemicals and to provide a clean surface for coating D.I. Recirculating rinse, followed by a D.I rinse Carry over of chemicals and other contaminants from previous steps. Must ensure that D.I. water quality is maintained

 

To read the rest of the article, written by Ron Lewarchik, please click here to head over to UL Prospector.

__________

Ron Lewarchik, Author of article & President of Chemical Dynamics

As a contributing writer, Ron pens articles on topics relevant to formulators in the coatings industry. He also serves as a consultant for the Prospector materials search engine, advising on issues related to optimization and organization materials within the database.