• PO Box 990, Harwich, MA 02645, USA

Multi 3.6 High Performance Epoxy System

Epoxies are known for their high chemical and temperature resistance in many diverse applications. However they have had limitations in aggressive solvents, such as methylene chloride, alcohols, such as methanol, both of which cause epoxies to swell rapidly fracturing the polymer network. Inorganic acids, such as nitric, will chemically attack and destroy the epoxy.

Increasing the cross-link density of the cured epoxy system will improve performance in these previously inhospitable environments. The difficulty with very high functionality epoxies is that they are nearly solid room temperature, cure very quickly with excessive exotherms and have a very low level of thru-cure at ambient cure.

ARCOR® Multi 3.6 Epoxy systems utilize the highest functionality resins and amine curing agents available to create epoxy coating systems designed for large scale applications with reasonable working times, limited exotherms and nearly complete cure at ambient temperature. The Multi 3.6 systems utilize epoxy Novolac resins with average functionality (reactive sites) of 3.6 and amine activators with average functionality of 6. The more reactive sites, the greater the twisting, turning, looping cross-links that will occur resulting in a tighter, more impenetrable cured film. The most commonly used hi-performance Novolac coatings have functionalities from 2.2 to 2.7. Even when used with hi-functionality amine curing agents, they still result in exponentially lower cross-link densities than when using the 3.6 Novolac. The problem with the available 3.6 functionality Novolac is hat they semi-solids at room temperature. The addition of the traditional monofunctional and difunctional diluents can reduce viscosity but the volumes needed, and the method of performance, result in vastly diminished performance of the cured system by reducing cross-link density. The use of traditional plasticizers can have the same effect with the added difficulty that they can flash from the cured system at the elevated temperatures further degrading the cross-link density.

ARCOR® Multi 3.6 Epoxy systems utilize a unique combination of diluents and plasticizers that allow the systems to be usable at ambient temperatures, cure at the ambient temperatures and actually improve cross-link density when exposed to elevated temperature service as the plasticizers used will polymerize. 

® Multi 3.6 Epoxy Novolac Systems utilize the highest functionality Novolac resins available with an average functionality of 3.6 epoxide groups. Table 1 shows measurements of reactivity of EE-101 & EE-111. These include get time, thin-film set time. Gel times are about 50% of what is seen in our standard Novolac, EE-10 & EE-11. Thin film set times are about 3 times faster. These demonstrate that the Multi 3.6 products have a reasonable working time and that the materials will develop cured properties allowing for quick return service.

Table 1
Ambient Reactivity & Cure

Intial Reactivity  
Gel Time, min, 150g mass16.115.2
Peak Exotherm Temp, ºF399405
Thin Film Set, hr  
@77 ºF (26 ºC)1.31.0
@40 ºF (4 ºC)6.05.3
DSC Reactivity, Initial  
Peak Exotherm @ ºF208207
^ H, J/g401415
7 Day Cure @ 77 ºF (25 ºC)  
Residual Exotherm, J/g37133
Tg, ºF131133

DSC Testing was done to estimate extent of cure of the Multi 3.6 systems under ambient and post-cure conditions. Initial reactivity is seen to be very high at ambient cure. This demonstrates that the Multi 3.6 systems reach a high degree of their temperature and chemical resistance even when heat cure is not available.
Table 2 demonstrates that post cure can enhance the overall cross-linking of the Multi 3.6 formulations improving performance in the most aggressive of chemical environments.

Table 2
Effect of Post Cure

DSC Reactivity, Initial  
Peak Exotherm @ ºF208207
^ H, J/g401415
Post Cure, 2 hr @ 135 ºF (57 ºC)  
Residual Exotherm, J/g3346
Tg, ºF156160
Post Cure, 2 hr @ 250 ºF (121 ºC)  
Residual Exotherm, J/g00
Tg, ºF207228

Table 3 shows the excellent chemical resistance of EE-101 when cured under ambient conditions. In all instances the EE-101 was intact after 28 day full immersion exposure. Post cure with heat will improve cross-link density enhancing performance as shown in Table 3.

Table 3
% Weight Gain
Ambient Cure

Cure7-day @ 77 ºF (25 ºC)
Chemical Resistance
Glacial Acetic Acid 98% Sulfuric Acid
1 Day2.39 1 Day0.23
3 Day4.08 3 Day0.47
7 Day6.40 7 Day0.77
14 Day9.59 14 Day1.57
21 Day11.96 21 Day1.39
28 Day13.36 28 Day1.57
Methanol 10% Lactic Acid
1 Day1.90 1 Day0.59
3 Day3.14 3 Day1.11
7 Day4.74 7 Day1.83
14 Day6.78 14 Day2.63
21 Day8.15 21 Day8.15
28 Day8.02 28 Day3.51
Toluene Butyl Cellosolve
1 Day0/05 1 Day-0.08
3 Day0.10 3 Day-0.03
7 Day0.16 7 Day-0.10
14 Day0.26 14 Day-0.12
21 Day0.37 21 Day-0.13
28 Day0.46 28 Day-0.10
1 Day-0.03   
3 Day0.04   
7 Day0.28   
14 Day0.80   
21 Day1.29   
28 Day1.65   

Table 4 illustrates the effect of heat cure on the Multi 3.6 formulations. As demonstrated in Table 1 & 2, the post cure of all Multi 3.6 formulations will further the cured state cross-link density improving chemical and temperature resistance.

Table 4
EE-101 & EE-111
% Weight Gain
Ambient & Heat Cure
Cure7 -day @
77 ºF (25 ºC)
Gel + 2 hr @ 135 ºF (57 VC)Gel + 2 hr @ 250 ºF (121 ºC)7-day @ 77 ºFGel + 2 hr @ 135 ºF (57 ºC)Gel +2 hr @ 250 ºF (121 ºC)
Chemical Resistance
Methylene Chloride     
1 Day16.26.970.9514.316.380.97
3 DayD*15.176.9131.8715.683.38
7 DayD33.4114.4531.6430.317.01
14 DayD30.3025.5031.9829.8112.16
21 DayD29.5728.4129.3028.0615.74
28 DayD28.9727.5726.2726.0119.78
10% Acetic Acid     
1 Day0.890.320.221.140.420.18
3 Day1.670.670.432.000.830.36
7 Day2.331.020.652.911.340.60
14 Day3.311.611.033.841.870.88
21 Day3.881.991.294.722.331.11
28 Day4.402.361.534.932.831.35
30% Nitric Acid     
1 Day0.490.460.260.450.450.33
3 Day0.770.690.650.710.700.61
7 Day1.171.020.951.121.140.96
14 Day1.761.481.361.641.551.34
21 Day2.281.911.732.221.901.63
28 Day2.752.312.102.402.452.11
10% Phenol     
1 Day0.580.250.230.500.300.16
3 Day1.080.500.380.870.580.31
7 Day1.760.820.631.411.010.53
14 Day2.621.320.962.141.590.82
21 Day3.291.701.222.882.231.14
28 Day4.012.141.503.162.481.24

The strength of the polymer backbone is displayed in the performance in Methylene Chloride. At ambient cure, even after weight gains in excess of 20%, the EE-101 coating shows no evidence of cracking after 28 days.