Ultra-low emission epoxy curing agent that provides long-term protection

In recent years, environmental protection regulations in the marine and protective coating industries have been increasing year by year around the world

Table 1 »Overview of the current situation of epoxy curing agents in epoxy coatings

Anti-corrosion coatings based on high solids systems are now becoming more and more common

Therefore, there is a need for ultra-low or zero-emission coating formulations on the market

Development of ultra-low emission cyclic amine epoxy curing agent

01Operationalperformance and varnish coating performance

In order to comply with strict emission regulations, we have developed two new products

Table 2 »Performance characteristics of ultra-low emission epoxy curing agent

These two products have been formulated, and the proportion of the standard liquid epoxy resin (LER) is 50phr

Figure 1 »Comparison of curing degree with liquid epoxy resin

In addition, in order to ensure that the coating is completely cured while avoiding vitrification in the cross-linking reaction, we have studied the changes in the degree of curing over time by differential scanning calorimetry (DSC)

In order to study the durability of the cured coating, another two sets of varnish-coated panels were prepared using the same formula of bisphenol A/F epoxy resin containing aliphatic epoxy diluent (Epodil 748)

02Ultralow emission

The European Commission defines the "lowest concentration of concern" (LCI) as the reported critical emission level of a single component (in μg/m3), which will affect the indoor air quality of residents and users during the long-term continuous use of the product
.
Based on this concept, the German Construction Product Health Evaluation Board (AgBB) has developed an interpretation plan
.
According to EN-ISO16000, the program verifies the cumulative emission products after 3, 7 and 28 days of coating in indoor applications, which are defined as follows:

VOC: Volatile organic compounds between C6-C16;

TVOC: total volatile organic compounds, the sum of VOCs ≥5μg/m3 between C6-C16 in emission products;

SVOC: >C16-C22 semi-volatile organic compounds;

ΣSVOC: Total semi-volatile organic compounds, the sum of SVOCs >C16-C22 ≥5μg/m3 in emission products
.

Figure 2 »Emission test results following the AgBB test standard

In order to determine the emission level of these new curing agents, we made a simple formula based on Ancamine® 2739 and conducted emission tests according to the AgBB scheme
.
The first measurement was taken 3 days after the coating was applied and cured at 23°C and 50% relative humidity (RH)
.
Figure 3 shows that VOC emissions are less than 1% of the highest standard, and no SVOC or carcinogens have been detected
.
The second measurement after 7 days of curing showed that the emissions were extremely low and no VOC, SVOC or carcinogens were detected
.
These results clearly show that coatings based on our new curing agent Ancamine® 2739 exceed the AgBB standards and can be classified as ultra-low emission coating systems
.

03 High-performance anti-corrosion performance

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1.
M.
Cook, Raising the Barrier for marine paints, European Coating Journal, pp.
38-47, 09 2019.

2.
C.
Hare, Protective Coatings-Fundamentals of Chemistry and Composition, Pittsburgh, Technology Publishing Company, 1994, pp.
1; 199; 210; 398-400.

3.
The Paint Directive, 2004/42/EC.

4.
Vedage,G.
, Raymond, W.
, Cook, M.
, Rasing, R, Benzylated polyalkylene polyamines and uses thereof, Patent US8147964B2, 2012.

5.
M.
Wacker, P.
Trawiel und GW Ehrenstein, Härtung von Reaktionsharzen Time-Temperature-Transition-Diagramm, Nürnberg: Sonderdrucke.

6.
Ancamine® 2712M and Ancamine® 2739, Evonik technical datasheet.

7.
Totev, D.
, Vedage, G.
, Raymond, W.
, Rufo, M.
, Cook, M.
, „High Performance Polyamide Curing Agents Offering Low Emissions and Long-Term Performance, SLF Congress, Helsinki, 2012.