Dynamically cross-linked maintenance filming for resilient floor coverings
IGF 21338 N
Elastic floorings are treated with floorcare products to increase lifetime and maintain optical properties. Floorcare coatings improve soiling, cleaning and wearing behavior of elastic floorings and provide protection against scratches, abrasion and walking imprints.
However, floorcare coatings have a limited service life as they are worn down by mechanical stress during use. As a result, protection of elastic floorings against mechanical wear and/or against migration of permeating soil components (barrier effect) is reduced or eliminated.
Especially for areas of heavy use, basic cleaning is necessary on a regular basis, where old coating has to be removed completely and new coating is applied. Renewal of floorcare coating is very time-, personnel- and cost-intensive and leads to considerable delays in operation of building operator.
A partial renewal of conventional floorcare coating is currently associated with considerable effort: Surface of old coating is sanded down and new floorcare product is applied afterwards.
After drying (at least 2 h), areas where renewed and old coating overlap must be aligned by mechanical treatment. Despite alignment, partial renewal of floorcare coating often results in visible areas between renewed and old areas.
In the case of soil migration into the floorcare coating, partial renewal is not possible. Since old coating is not removed completely, soil embedded in the coating would also remain on elastic flooring.
Dynamically cross-linked floorcare coatings for elastic flooring were therefore developed in the research project. Such coatings are highly resistant to mechanical stress during use and can be renewed with little effort, either partially or completely. Removal or pre-treatment of old coatings is not necessary.
Linkage points of polymer network (dynamic covalent bonds) of such dynamically cross-linked floorcare coatings are in a temperature-dependent equilibrium. Here, a dynamic, covalent bond is only broken when a new bond is formed at the same time (associative bond exchange), i.e. number of linkage points in the network and consequently its cohesive force remain the same.
Under conditions of use (room temperature), speed of associative bond exchange reactions in polymer network is negligible, so that dynamically cross-linked floorcare coating is in a solid state of high dimensional stability and wear resistance.
Under regeneration conditions (temperature e.g. 90 °C), associative bond exchange reactions in the polymer network are fast, and dynamically cross-linked floorcare coating is in a flowable, mechanically deformable state. Local damage is automatically compensated.
Dynamically cross-linked floorcare coating from peripheral areas of the local damage flows into these cavities and fills them (thermally induced self-healing of the dynamically cross-linked floorcare coating).
In the case of extensive damage, partial or full-surface renewal of dynamically cross-linked floorcare coating is possible with the formation of a homogeneous polymer network.
Application or reapplication (e.g. spray application) of the dynamically cross-linked floorcare coating is carried out in form of liquid, low-viscosity prepolymers in which dynamic covalent bonds are already present.
The polymer network of floorcare coating is formed via thermally initiated radical polymerisation of the prepolymers.
In the presence of old dynamically cross-linked floorcare coating on elastic flooring, thermal treatment and resulting rapid bond exchange reactions lead to the formation of a homogeneous network of old and new coating.
A fast, targeted temperature increase and a homogeneous temperature distribution are achieved by NIR absorbers embedded in the dynamically cross-linked floorcare coating (excitation with suitable light sources, e.g. NIR LEDs).
If soil enters the network structure, it is also possible to partially or completely remove dynamically cross-linked floorcare coating.
Due to the high cohesive strength of the dynamically cross-linked floorcare coating with simultaneous low adhesion to elastic flooring (removal of mechanical anchoring of coating in the flooring due to its flowability as well as temperature-related weakening of physical-chemical interactions between coating and flooring) under regeneration conditions, coating can be detached from the elastic flooring over the entire surface (e.g. in strips) using a suitable sharp-edged tool (e.g. stainless steel scraper).
The research report is available on request from FRT.