| dc.description.abstract | Laminated flooring is an important part of the decorative laminates market. High pressure laminates in particular are preferred products for flooring due to their outstanding properties such as fire and stain resistance, as well as resistance to abrasion, impact and scratch. The functional and physical properties balanced by low cost and aesthetics account for the large presence and increasing demand for these laminates both in residential and institutional sector.
Surface properties of laminated flooring are therefore of crucial importance and these properties are influenced to a great extent by the top layer. Currently, the top layer ( or overlay) of a Berry Alloc laminate consists of a melamine formaldehyde (1,1F) resin impregnated paper (having a weight of 60-100 g/m2) with up to 50 g/m2 alumina (AlzO3) particles and small amounts of other additives. These additives are curing agent to ensure that the liquid component solidifies quickly, wetting agent and release agent.
There are several ways of improving the properties of the laminates, and a closer look at the composition of the overlay will influence the scratch resistance, wear resistance, chemical resistance and impact resistance. These properties can be improved by adding different ceramic particles and ensuring a good bonding between the particles and the polymer matrix. Self-healing is another important aspect which can further increase the durability of high pressure laminates.
The addition of the ceramic particles is one of the most important factors to improve performance. In this work, the influence of ceramic particles load, size, morphology and distribution into the matrix resin was studied using AlzO3 particles in the 0.5-44 μm size range. The mechanical properties of the laminates depended on the AlzO3 content, size and morphology. Increased wear was observed with increasing particle loading and size, while the impact and chemical resistance were improved for particles with smaller size and lower aspect ratio. Homogeneity of the particle distribution in the polymer matrix and the quality of the filler/matrix interface, as well as the position of the particles within the laminate were also found to be important for the mechanical behavior of the laminates. Improvement of the resistance to scratch in particular was achieved using silane coupling agents to enhance the interface strength and the degree of dispersion of the particles within the resin. Placing the ceramic particles above the overlay lead to increased wear resistance compared to the traditional way of adding them between the overlay paper and the decorative paper. The influence of other ceramic fillers such as titanium dioxide (TiO2) , silicon carbide (SiC) and yttria-stabilized zirconia (YSZ) was studied and it was found that the addition of these particles generally improved the scratch and wear resistance of the melamine resin.
Another key goal of this work was to develop a product with self-healing ability by using microencapsulation technology. The synergetic effect of ceramic particles, the :MF matrix resin and the embedded self-healing agent would increase laminate floors' lifetime and consequently their market value. Epoxy microcapsules were prepared by interfacial polymerization of epoxy resin droplets with ethylenediamine (EDA) and tetraethylene triamine (TEI A), and the capsules were characterized by scanning electron microscope (SEM), thermogravimetric analysis (TGA) and Fourier Transform Infrared Spectroscopy (FTIR). The size of the capsules can be tuned by adjusting the preparation parameters such as the agitation rate and the emulsifier concentration. However, for all the capsules, a wide size distribution from < 1 μm to as much as > 300 μm was obtained, probably due to turbulent flow around the propeller. The morphology of the capsule surface was rough which is most likely an advantage as it would provide good interfacial adhesion with the matrix. The obtained epoxy microcapsules showed thermal stability up to well above 200 °C and are therefore are suitable for the manufacturing temperature of laminate floors. Furthermore, FTIR spectra showed the existence of the cross-linked shell material. Subsequently, laminates containing epoxy microcapsules were manufactured, and the behavior and self-healing effect were investigated by micro scratch testing and microscopy observation. As the capsule concentration was high, the preparation of the laminates was challenging due to the increased viscosity of the uncured resin. The experimental results demonstrated however that the microcapsules are promising for adding self-healing properties to the laminates. Further work should include finding a suitable way to incorporate the capsules into the laminates. | nb_NO |
