Description:
CN820 is an energy-curable oligomer that is used in ink, adhesive, and coating formulations to promote adhesion to a wide variety of substrates. The properties and features of CN820 are presented below.

Discussion:
To demonstrate the adhesion-promoting versatility of CN820, three studies are presented below. These include a classic metal coating, a screen ink applied over a variety of substrates, and a metal coating subject to elevated temperature. In each case, the crosshatch adhesion test (ASTM D3359) is used to evaluate adhesion quality. This test involves cutting a grid of 100 squares into the coated panels. 3M^® #610 tape is applied to the scribed area and pulled at a 90 degree angle. The number of coating squares remaining indicates the percent adhesion.

Classic Metal Coating
This study evaluated the adhesion impact of CN820 on cold-rolled steel. A base formulation was combined with CN820 in various proportions and applied using a drawdown bar to yield a 5-micron film. The formulations and cure conditions are shown below.

The graph below shows crosshatch adhesion results for various blends of CN820 and the base formulation. Note the upward trend in adhesion, resulting in 100% at 30 parts CN820.

An extension to this study showed that the CN820 films survived 48 hours of exposure to a 25% solution of NaOH without any visual sign of degradation.

Screen Ink Study
In this study, CN820 was blended with three different acrylate monomers in the same proportion and subsequently added to a typical screen ink formulation to evaluate the adhesion impact of various chemistries on assorted substrates. Blend 1 evaluated CN820 with a hard, aggressive monomer - SR238 (hexanediol diacrylate). Blend 2 examined CN820 with a flexible, aggressive monomer - SR339 (2-phenoxyethyl acrylate). Blend 3 studied CN820 with a hard, non-aggressive monomer - SR506 (isobornyl acrylate). The formulation protocol is shown below.

The blend containing SR238 demonstrated the lowest adhesion. It was relatively brittle and responded poorly to the 90° bend test. The blend with SR339 showed generally good adhesion. Due to the aggressive nature of SR339, it was the only blend to demonstrate 100% adhesion to PET. Cured inks, however, showed low scratch resistance. The blend based on SR506 showed the best overall adhesion results. It also demonstrated lower shrinkage than the other monomer blends and good ink scratch resistance. The crosshatch adhesion results for each CN820/monomer blend are shown below.

Metal Coating Subject to Elevated Temperature
This study used a typical metal-coating formulation to evaluate various levels of CN820 for adhesion promotion. The CN820-based formulations were applied to unanodized, untreated aluminum at a 25-micron film thickness. Each formulation survived a 30-inch drop in the direct impact test (ASTM D2794).The formulations tested are shown below.

Crosshatch adhesion testing was performed under ambient air, after 15 minutes in boiling water, and after 15 minutes in boiling water, followed by an 80 °C hot water bath for 1 hour. As shown below, the level of CN820 is directly related to the quality of adhesion under these extreme conditions, and 100% adhesion was maintained at the upper level of CN820 tested.

The listed properties are illustrative only, and not product specifications.  Sartomer Company disclaims any liability in connection with the use of the information, and does not warrant against infringement by reason of the use of its products in connection with other materials or in any process.

Sartomer Company, Inc.
502 Thomas Jones Way
Exton, PA 19341
U.S.A.
1-800-SARTOMER
610-363-4100
www.sartomer.com