Page 176 - CW E-Magazine (20-5-2025)

Special Report

tables 1 & 2 give a comparison of conventional epoxy phenolic and alkylated ment has to do with dry film thickness
amine epoxy coatings. (DFT) and cracking. Whereas phenolic
epoxy coatings have a narrow tolerance
table 1: conventional Epoxy Phenolic for High and cuI Service. on their dry film thickness before crack-
temperature touch dry (hours) Hard dry (hours) Min overcoating ing starts to occur, alkylated amine
(hours) coatings are able to tolerate a wider
-5 C (23 F) NA NA NA range of thicknesses, which reduces the
10 C (50 F) 8 16 36 risk of cracking (Tables-3 and Table-4).
15 C (59 F) 7 12 24 Conventional epoxy phenolic coating
25 C (77 F) 6 8 16 was applied on panels with 1x8 mils, 2x4
40 C (104 F) 3 6 16 mils, 2x6 mils, 2x7 mils, 2x8 mils, 2x9
o
o
table 2: Alkylated Amine Epoxy for High Heat and cuI Service. mils and 2x10 mils DFT at 120 C, 150 C,
o
and 200 C, as shown in Table-3. Light
temperature touch dry (hours) Hard dry (hours) Min overcoating grey indicates no visible defects, medium
(hours) grey indicates cracking and defects
-5 C (23 F) 7 10 14 observed around weld only, and dark grey
10 C (50 F) 5 8 10 indicates cracking and defects observed
20 C (68 F) 4 6 7 around face of the panel. Alkylated amine
35 C (95 F) 2 4 4 epoxy coating was applied on panels with
1x8 mils, 2x4 mils, 2x5 mils, 2x6 mils,
improving the operation flow because it table 3: tolerance to dFt over-Application for a conventional
allows for faster movement of the pro- Epoxy Phenolic.
ducts being coated from the shop to the
field where they will be implemented, conventional Epoxy 243 F (120 c) 302 F (150 c) 392 F (200 c)
thus reducing bottlenecks at the final Phenolic
point of use. Getting them out of the 1 x 8 mils 1 x 8 mils 1 x 8 mils
shop quicker can also reduce bottle- 2 x 4 mils 2 x 4 mils 2 x 4 mils
necks in the production facility as well.
2 x 6 mils 2 x 6 mils 2 x 6 mils
Another key advantage and note- 2 x 7 mils 2 x 7 mils 2 x 7 mils
worthy takeaway from the tables is 2 x 8 mils 2 x 8 mils 2 x 8 mils
the allowable temperature range. In- 2 x 9 mils DFT 2 x 9 mils 2 x 9 mils 2 x 9 mils
cumbent epoxy coatings are limited stoved at 392 F (200 C)
to a minimum application temperature 2 x 10 mils 2 x 10 mils 2 x 10 mils
of 10°C, whereas the alkylated amine Light grey - good, no visible defects, Medium grey - cracking and defects observed around weld only.
coatings can be successfully applied at Dark grey - cracking and defects observed around face of panel.
temperatures below freezing. Not only table 4: tolerance to dFt over-Application for a novel Alkylated Amine Epoxy.
that, but in situations involving below-
freezing temperatures where alkylated Alkylated Amine Epoxy 243 F (120 c) 302 F (150 c) 392 F (200 c)
amine epoxy coatings were applied still
had faster curing times across the board 1 x 8 mils 1 x 8 mils 1 x 8 mils
than a phenolic epoxy coating applied 2 x 4 mils 2 x 4 mils 2 x 4 mils
at 15°C. 2 x 5 mils 2 x 5 mils 2 x 5 mils

Improving quality with alkylated 2 x 6 mils 2 x 6 mils 2 x 6 mils
amine epoxy coatings 2 x 7 mils 2 x 7 mils 2 x 7 mils
Quality enhancements can also be 2 x 8 mils 2 x 8 mils 2 x 8 mils
realized when using an alkylated amine 2 x 12 mils DFT
epoxy coating versus a phenolic epoxy stoved at 392 F (200 C) 2 x 12 mils 2 x 12 mils 2 x 12 mils
coating. One notable quality improve- No visible defects found in any panel with alkylated amine epoxy.

176 Chemical Weekly May 20, 2025

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