"Let's make the perfect combination" is the motto under which the Munich-based chemical company Wacker is showcasing highly efficient coating compounds for the paper and film coating industry at Labelexpo Europe 2015. The focus is on four new silicone polymers for industrial label applications. They are solvent-free and cure extremely quickly, which is why they are ideal for cost-effective release coatings. The products belong to the new Dehesive SFX product family, which will be presented to a wide professional audience for the first time at the Labelexpo. The tradeshow takes place in Brussels, Belgium, from September 29 to October 2.Release coatings with silicone polymers of the new Dehesive SFX product family are ideal for high-speed labeling machines. The new silicone grades are very cost-efficient. With their help, the proportion of platinum catalyst in the coating system can be lowered by up to 60 percent compared to conventional silicone systems.
The new products are solvent-free and cure by a platinum-catalyzed addition reaction. Due to their high reactivity, the silicone polymers require very little catalyst to cure fully. Compared to conventional coating systems, platinum savings of up to 60 percent are possible with the Dehesive SFX system. This makes production considerably more cost-effective for release-paper and label manufacturers. In addition, the properties of the new silicone polymers can be optimized specifically for fast labeling processes.
The polymers’ high reactivity stems from their molecules' star-like branched structure, in which every silicone chain branches even further. At the end of every branch, there is a vinyl group, which makes addition curing possible. Due to this three-dimensional molecular architecture, Dehesive SFX polymers are able to crosslink significantly better than conventional linear silicone polymers.
Thanks to this high reactivity, coating systems based on Dehesive SFX are ideal for use in high-speed coating equipment. Even at low catalyst dosage, they yield a fully cured silicone layer. The resulting release properties are ideal for machine delamination at high throughputs. Due to the flat release force profile, very little force is required for delamination even when labels are removed very quickly – such as during mass production of consumer goods. The release properties do not change, even after protracted storage of the laminate.
The new star polymers are tailored to high-speed applications and differ in the number of branches, vinyl content and viscosity. The curing rate, release force profile and coverage of the substrate surface can be specifically adjusted to customers' requirements.
- Of the new silicone polymers, Dehesive SFX 195 has the lowest viscosity. This product is ideal for coating smooth and dense release papers. The substrates are covered so well that low coating weights are possible. With Dehesive SFX 195, low release forces are possible at high peel rates.
- Within the new product family, Dehesive SFX 250 achieves the highest curing rate and makes the biggest platinum savings possible. A release layer based on this polymer is characterized by an extremely flat release force profile. This is an advantage when particularly high peel rates are the target.
- Dehesive SFX 280 features an extremely balanced range of properties. The polymer cures rapidly and is suitable for the efficient coating of dense surfaces as well as porous ones. It has a flat release force profile and is thus the allrounder among the new, highly branched polymers.
- With its comparatively high viscosity, Dehesive SFX 380 is the specialist for use on porous papers. The polymer is able to cover absorbent substrates excellently. Release forces remain low even at high peel rates.
Dehesive SFX with AMA anti-misting additive
During the coating of release papers, misting may occur, especially at high coating speeds. This is undesirable. On the one hand, because equipment can become dirty as a result; on the other, because the quality of the silicone release layer decreases when mist deposits on the freshly coated release liner.That's why Wacker also offers its new Dehesive SFX polymers with integrated anti-misting additive AMA. At high coating speeds, AMA prevents misting and thus significantly improves the coating result.
Wacker has been developing and manufacturing silicone-based paper and film coating systems for almost 50 years. Silicones from the Dehesive product line are organosilicon compounds specially developed for the production of silicone release liners and films. Their chemical structure ensures good release properties in contact with adhesives. Substrates coated with Dehesive will easily peel off from the adhesive and are thus suitable for protection of the adhesive layer of PSA labels, adhesive tapes and self-adhesive products. Moreover, the silicone systems demonstrate processing advantages such as good leveling and rapid curing.
