In Part 1 of this series, we looked at a checklist for beginning a waterborne coating project. In Part 2, I detailed how additives can help achieve desired formulation results. Now we’ll discuss the different stages of formulation, pigment selection, and specific types of ingredients.
Let’s start with what I would call a “canned direct-to-metal (DTM) formula,” found under Grace’s Formulation #EPS® 2535 SP-3 on ULProspector.com:
POUNDS | GALLONS | RAW MATERIAL | SUPPLIERS | INSTRUCTIONS |
80.0 | 9.60 | water | add in order with good agitation | |
18.0 | 2.05 | Disperse-ayd® W-22 | Elementis | |
3.0 | 0.41 | Surfynol® 104A | Air Products | |
1.0 | 0.13 | AMP-95® | Angus | |
1.5 | 0.17 | BYK®-024 | Byk | |
100.00 | 2.87 | Tiona® RCL-535 | Millennium | add in order with good agitation |
200.0 | 9.06 | Atomite® | Nexeo Solutions | |
15.0 | 1.00 | Shieldex® AC 5 | Grace | |
25.0 | 1.00 | HALOX® SZP–391 | Halox | Disperse to 6+Hegman grind |
Combine the following ingredients in a separate vat from the mixture above, and mix thoroughly. This is your master vat.
POUNDS | GALLONS | RAW MATERIAL | SUPPLIERS | INSTRUCTIONS |
425.0 | 48.85 | EPS® 2535 | EPS Materials | let down in order |
0.5 | 0.006 | BYK®-024 | Byk | |
1.5 | 0.16 | Nuosept™ 95 | ISP | Now add grind to this vat |
Then add grind in a separate vat, with constant agitation.
POUNDS | GALLONS | RAW MATERIAL | SUPPLIERS | INSTRUCTIONS |
130.9 | 15.71 | WATER | Premix next three items | |
10.0 | 1.20 | 4% Sodium Nitrite | before adding solvent | |
4.0 | 0.45 | RHEOLATE® 1 | Elementis Specialties |
Then add the solvents.
POUNDS | GALLONS | RAW MATERIAL | SUPPLIERS | INSTRUCTIONS |
38.3 | 5.01 | Dipropylene Glycol Normal Butyl Ether (DPnB) | Lyondell | add to above premix |
19.1 | 2.05 | Santicizer 160 | Era Polymers | Add to above premix and then add total mixture to above master batch with good agitation. |
1.0 | 0.11 | ACRYSOL™ RM-825 | Dow Coating Materials | Premix and add for viscosity |
1.0 | 0.11 | water | ||
1074.80 | 100.00 |
Let’s look a little more closely at the additives in this type of formulation.
The first mixture is for the color part of the formula. Starting with water, you then add an ingredient to help disperse the “powder” that will go into the grind stage. In this case, that dispersant is Disperse-ayd W-22. The choice depends on the PVC (Pigment Volume Concentration) level you intend to achieve.
If you have a higher PVC, ask a supplier which dispersant they recommend to try, as well as their recommendation for a lower PVC. Formulating the correct PVC is critical in optimizing your coating. As in this case, an additional disperse aid assisted in long term stability of the formulation.
Defoamers are always used in color formulations. In this example, Surfynol 104A not only defoams, but has an added benefit of providing dynamic wetting. The use of multiple defoamers in not unusual as in this case, where BYK-024 was also used several times. This is a typical case where I would have chosen a different type of defoamer so as not to have these compete.
Pigment selection is up to the formulator, as well as your choice of type of filler to offset the cost of the TiO2 in your formula. In this example, we see a reduced amount of TiO2 and an increased amount of Atomite. Check your selection, for both have different particle sizes available. Some grind down well, some do not! This formula also incorporated two anti-corrosion pigments.
Resin selection is still dependent on the very first checklist we created in Part 1 of this article. This formulator chose a styrenated acrylic emulsion, as it is supposed to offer outstanding corrosion resistance, adhesion and early water resistance. Acrylics are known to promote adhesion, where urethanes bring the chemical resistance and exterior durability.
We finish off the film formation with some solvent packages. The use of DPnB (25% on resin solids) is recommended to form films as low as 40°F while offering excellent corrosion resistance and open dry times for finishing large objects. Small additions of plasticizer, such as Paraplex WP-1, Santicizer 160, or KP-140 may enhance the film properties.
Then finally we finish things off with a viscosity adjustment. It may be necessary at times to use a package of Rheology modifiers, to attain viscosity control as well as proper sag resistance. Among those showing particular success with this resin system were:
- Acrysol RM-825 (Dow Coating Materials)
- ACRYSOL™ RM-2020 (Dow Coating Materials)
- Tafigel® PUR 60 (Munzing Chemie)
- RHEOLATE 1 (Elementis)
- Attagel® 50 (BASF)
WOW! Finally, we have completed a product. As you can see, not as easy as you may have thought. Because now comes the hard part: you must take your creation and test it. Simple testing was partially covered in your initial product selection.
ASTM offers many standard tests for your performance to be verified.
Now all that remains……………. Is there a market for this product? Welcome to my world!
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Thanks for making it looks so easy! I will surely give this a try. Wish me luck.