DEVELOPMENT OF NEW ADHESIVE ADDITIVES FOR SOLVENT BASED PRINTING INKS
04.05.2021
The printing on polyolefin materials has always been a challenge. If separate methods for raising the surface tension such as flame treatment, corona or plasma treatment cannot be applied, it is necessary to add adhesive additives to the printing inks to obtain adequate adhesion with the polyolefin.
Pinneberg/Germany, May 4th, 2021 – TRAMACO’s portfolio offers highly efficient adhesion promoters, which are extensively used by the automotive industry for varnish applications. Xylol, the standard solvent for TRAPYLEN® adhesion promoters is among others used for solvent based varnish systems.
Solvent based printing inks generally are BTX-free and therefore difficult for many CPO applications. TRAPYLEN® 186 S has been the first CPO which shows a very good solubility in esters, like ethyl acetate, butyl acetate or ketones (e.g. MEK) because of its high chlorine content of 43 % and the low molecular weight of approx. 15,000 g/mol. For this reason it still today is successfully marketed for printing inks.
It is an important development objective of new adhesion promoter systems to improve the adhesion for polyolefin materials. This may be reached by lowering the chlorine content of CPOs. But a declining chlorine content causes continued reduction of solubility of a CPO in esters and ketones – thus the development of new products for printing inks is a great challenge.
Another product of TRAMACO with good solubility in esters and ketones for printing ink applications is TRAPYLEN® 187 S with a chlorine content of 36 % and a molecular weight of approx. 30,000 g/mol. This product is especially qualified for unmodified PP because of a better adhesion as of TRAPYLEN® 186 S.
This is the very reason for the importance of the further development of CPOs with even lower chlorine content to realize better adhesion on difficult substrates. Products with higher molecular weight are of the same importance to improve the resistance to chemicals – on the assumption that the solubility in esters and ketones will not deteriorate.
Other products with a chlorine content of approx. 30 % and a molecular weight of about 100,000 g/mol even show promising results.
TRAMACO’s aqueous adhesion promoters are used for aqueous printing inks. These adhesive additives can be added directly to an aqueous printing ink due to the good compatibility