Additives play an important role during the production of high-quality tableware.
Essential goals are energy savings in the spray dryer, optimisation of the pressing granules and the faultless glaze application.
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Zschimmer & Schwarz
Ceramic AuxiliariesMax-Schwarz-Strasse 3–5
56112 Lahnstein | DET +49 2621 12-485
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During the manufacture of ceramic products, energy costs have a considerable share in the overall expenses of the final product. Deflocculating additives help to save water and energy resources, and to increase the production output. The slip properties (viscosity, thixotropic behaviour, structural viscosity, dilatancy, rheopexy and Newtonian flow behaviour) can be adjusted according to the customer’s requirements.
Deflocculants used for the casting of ceramic bodies can help to save water and energy resources, and to augment the production output in a similar way as do those deflocculants applied for the spray process. The ceramic slip properties – viscosity and density – are adjusted according to the customer’s requirements, to a large extent.
During the preparation of slips, foam can form through surface-active substances and also through the mechanical energy input. Our antifoam agents prevent foam formation during preparation or, respectively, immediately destroy foam that has already formed.
The efficiency of the pressure casting process, as well as the cost effectiveness of conventional slip casting, are dependent on the output per unit time, which in turn depends on the casting rate. The use of filtration agents leads to the agglomeration of fine particles, and a more even de-watering of the casting slip is the result. A regular density and a uniform shrinkage allow the production of a homogeneous cast that is free from internal stresses. To a large extent, separation and sedimentation phenomena are prevented. Furthermore, filtration agents confer good interlocking at transitions from hollow casting to core casting, and better removal from the mould.
Biocides are required for the application of organic additives and/or raw materials to counteract their deterioration caused by micro organisms such as bacteria, yeasts or fungi, and consequently to guarantee long-term stability.
The pressing agents and lubricants are used, amongst others, for isostatic pressing of ceramic bodies, where they promote better shaping characteristics. They facilitate the flow of the pressing granules under pressure, thus leading to a more homogeneous compaction owing to their simple destruction without leaving residual granulate structures. The reduction of the internal stresses avoids cracks and crawling at the edges during the technological steps that follow. When using metal moulds, the friction between pressed piece and mould wall is reduced, which in turn allows a prolonged working life of the moulds.
In the tableware sector, temporary binders are used in pressing, casting and plastic bodies to increase the green and dry breaking strength and, hence, to minimise waste and scrap.
Temporary binders are used for spray bodies to improve the green and dry breaking strength. In the tableware industry, this allows to minimise the reject rate. The granulate density must be adjusted, on the one hand, to the extent the granules do not disintegrate during transport, but on the other hand, can be easily destroyed during pressing. Granulate plasticity and strength, as well as elasticity of the binding matrix, can be controlled in a targeted manner.
Dispersants are used in glazes and engobes to specifically influence the rheological properties and solids content of the slip. Depending on the particular glaze and/or engobe type as well as the application procedure, the desired aim is maximum density at optimum rheological properties without sedimentation.
During the preparation of slips, foam can form through surface-active substances and also through the mechanical energy input. Possible consequences can be defects in the glaze in the form of pinholes or dimples. Our antifoam agents prevent foam formation during preparation or, respectively, immediately destroy foam that has already formed.
Biocides are required for the application of organic additives and/or raw materials to counteract their deterioration caused by micro organisms such as bacteria, yeasts or fungi, and consequently to guarantee long-term stability.
Rheological additives have an important function: they create the prerequisites for a defined reproducible adjustment of glaze rheology, and they guarantee constant results with applications by hand and spray robot on vertical surfaces. Moreover, rheological additives allow a flexible adjustment of the flow behaviour, a stable viscosity, a high glaze thickness as well as an improved adhesion and an increased touch-resistant finish.
Specific suspension aids are used to prevent sedimentation of glazes. Suspension aids are either employed to adjust ready prepared glazes or introduced previously, during preparation via the glaze mill.
Temporary binders bring about an increase in mechanical resistance at the surface of glazes and engobes, hence leading to an improved touch-resistant finish. This provokes a good bond between the glaze and the body. Glaze runs on the surface as well as crawling at the edges are prevented by this.
Specific cleaning agents prevent early aging of the resin pressure casting moulds. Our low-hazardous cleaning agents have good wetting properties to loosen deposits, and excellent complexing properties, which allow the rinsing out of multivalent cations. The cleaning agents can either be used for cleaning the mould pores and capillaries, or for cleaning the mould surface.
On account of their surface activity, plaster additives act as deflocculants, which means: the solids content in the plaster slurry can be increased whilst maintaining the same processing consistency. This intensification of the plaster/water ratio brings about an augmentation of the mechanical resistance, which particularly becomes obvious as an improved abrasion resistance. In turn, this can lead to a prolonged working life of the plaster mould.
Release agents bring about good separation of the plaster negative cast from the master mould. Owing to the water-soluble emulsion system, the absorption capacity of the plaster moulds will be unaffected.
