Water-based tape casting and manufacturing of laminated structures

Water-based systems are the trend of the future in tape casting as well as in many other applications. One advantage of water-based systems is that the solvent is much easier to handle without risks of intoxication, explosions or fire. Some difficulties in using water-based systems in tape casting are that the tapes are more prone to cracking during drying and that the evaporation of water is slower, The solution to these problems is good dispersion and increased solids loading, which reduces the tendency to cracking and the amount of water that must be evaporated. Water-soluble binders tend to increase the viscosity of the suspension. Latexes, i.e. dispersions of non-water soluble polymer particles in water, have a less pronounced effect on the viscosity of the suspension. By using latex binders it is possible to develop water-based systems that have low viscosity and good casting properties. Tapes with latex binders are easy to laminate. If latex with a glass-transition temperature below room temperature is chosen it is possible to laminate the tapes at room temperature. Natural starches consist of particles with narrow size distributions and equiaxed shapes. These starches are easy to disperse in water and compatible with the latex binders. By laminating and sintering tapes with and without starches it has been possible to create dense/porous structures with crack-deflecting properties. These structures have been shown to have excellent damage resistance to thermal shock.