What is Carrier Gel all about?
Carrier Gel® is a liquid polymer supplied as a low viscosity emulsion.
When added in starch or even flour adhesive formulations after neutralization with an appropriate base like NaOH the water gel suspension is formed acting as the "carrier part" of the batch.
It replaces 100% of the pre-cooked part of starch-based formulations.
Thanks to its resistance to alkali, Carrier Gel® act in high pH environments.
When dosed in water-based starch or flour adhesives, Carrier Gel® generates very stable viscosity and high shear thinning properties.
The entire batch is transformed into a pseudoplastic fluid with high thixotropic* properties.
A very short adhesive’s film structure enables very low glue consumption and excellent bonding.
* Thixotropy is a time-dependent shear thinning property. Certain gels or fluids that are thick or viscous under static conditions will flow (become thinner, less viscous) over time when shaken, agitated, shear-stressed, or otherwise stressed (time dependent viscosity). They then take a fixed time to return to a more viscous state. Some non-Newtonian pseudoplastic fluids show a time-dependent change in viscosity; the longer the fluid undergoes shear stress, the lower its viscosity. A thixotropic fluid is a fluid which takes a finite time to attain equilibrium viscosity when introduced to a steep change in shear rate. Some thixotropic fluids return to a gel state almost instantly, such as ketchup, and are called pseudoplastic fluids.
Stress generated by the Glue & Doctor roll enables a very thin glue film.
Glue-rolls run at +/- 98% production speed of board = 200 – 400 m/min
When adhesive is picked-up by the glue roll the stress goes up and the viscosity drops instantaneously.
This generates a very thin glue film. Often at mechanical minimum settings.
At contact point with paper the stress is stopped immediately and initial viscosity returns
enabling excellent fiber penetration just at the tip of the flute.
