High Performance Fillers for elastomer applications
Elastomers are dimensionally stable but flexible and ductile polymers e.g. fluorelastomers or silicones. These polymers find use e.g. in seals, tires, cables, hoses, conveyor belts, floor covering and in medical technology, and everywhere else where the large elasticity of the final product is important. These fillers have a substantial improving influence on the mechanical properties (shore-hardness, E-module, tensile strength, etc.), also on the electrical characteristics (dielectric strength). In addition the application of these fillers allows a good to excellent stainability.
Fluorelastomer applications: TREMIN®
Fluorelastomers are high-specialized materials for the most demanding applications in engine and mechanical engineering as well as in plant construction for chemistry. Only with fluorelastomer seal rings high temperature applications and very sophisticated chemicals are possible. Granular, silane coated wollastonite flours TREMIN® 283 are already successfully used for many years as functional fillers in fluorelastomers with the focus on tensile strength and dimensional stability in order to adjust the hardness. Apart from the good reinforcement in fluorelastomers TREMIN® 283 provides also the advantage of stainable bright mixtures. These optimised fluorelastomers are ideally suited for the above mentioned applications under special conditions, e.g. high mechanical load and high temperatures.
With TREMIN® 283 filled fluorelastomers can be characterised by the following properties:
• outstanding dimensional stability
• well stainable characteristics
• large tear
• large tensile strength
Wollastonite is a naturally occurring calcium silicate, which is formed from silicon dioxide and calcium carbonate at a temperature of approx. 450°C. The structures of the individual wollastonite particles on the one hand depend on the geological formation and are on the other hand strongly by the selected preparation technique. Quarzwerke grinds granular particles with a low aspect ratio (LAR) to various grain sizes for elastomer applications. Depending on customer requirements the product may be further improved by a surface treatment.
Rubber applications: CHINAFILL
It is impossible to imagine our everyday life without the extremely flexible material rubber. As definition all vulcanised natural or synthetic india rubbers, e.g. styrole butadiene (SBR), nitrile butadiene (NBR) or ethyl-propylene- dien (EPDM), are called rubbers. The applications of rubber polymers can be found where the material elasticity has a significant importance, e.g. in tires, floor covering, hoses, cables and conveyor belts or also in various household products. The thin lamina shaped kaolin as chemically inert filler is weather proof. Coarse kaolin types (so-called “soft clays“) show a reinforcement effect in rubber, the fine kaolin types (“hard clays“) provide even a stronger reinforcement effect.
With kaolin as additive tensile strength, tear and E-modulus are increased. Besides the bright CHINAFILL Kaolin allows the production of well stainable products. In cables kaolin also causes an increase of the isolation characteristics.
With CHINAFILL filled rubbers can be characterised by the following properties:
• outstanding tensile strength
• large tear
• increased E-modulus
• very well dyable characteristics
• increased electrical isolation characteristics
Kaolin is a naturally occurring raw material, which is improved to an industrial filler by extensive processing. Kaolin is separated of its accessory minerals by water separation technique. The classification into different grain size distributions takes place through drum washers, cyclone classifier and centrifuges. Subsequently dewatering by sedimentation, filtration and drying takes place. Bleaching agents and magnetic separators refine several kaolin products.
Silicone applications: SIKRON® and SILBOND®
Silicone is an elastomer which combines the unique properties of quartz and rubber: It is extremely flexible, very heat resistant, hydrophobe and comes with a large electrical dielectric strength. In contrast to rubbers, silicones maintain their characteristics within a large temperature range. Therefore silicone polymers are used for highly stressed seals, isolations and plastics mouldings. Anyhow without these polymers medical technology, electronic industry and households are impossible to imagine.
In contrast to the needle-shaped wollastonite and lamina shaped kaolin, quartz and cristobalite are inert and due to their structure rather round and compact. In addition to the untreated types of the SIKRON® family the surface-treated SILBOND®-types are also available. For seals and cables mainly quartz is used, in particular the type SIKRON® SF 600 and/or the coated variants SILBOND® 600 TST and SILBOND® 600 RST. The treatment of the filler with trimethyl silane (- RST) provides a low viscosity during the processing of the silicone. By employment of this filler the electrical and mechanical characteristics of the silicone part can be specifically influenced (e.g. increase of the electrical isolation properties).
Regarding silicones for dental casting compounds the cristobalite based types SIKRON® SF 3000, 6000 and 8000 and the with suitable silanes surface-treated SILBOND® variants are preferably used. The selection of the suitable fillers enables a very high filling degree with acceptable viscosity of the casting compounds. That way the highest possible precision of the casting compound can be realized by minimisation of the contraction during reaction. An excellent staining power and desired elasticity as well as shore hardness of the compound can be achieved by application of the very white cristobalite.
It is to be emphasised that all quartz and cristobalite powders, as described here, contain a very low fraction of coarse particles. This is crucial for the functionality of the applications. Coarse particles as inhomogeneities in the compound structure would strongly impact the sealing characteristics of seals or the electrical-isolating characteristics of cables.
With SIKRON® and SILBOND® filled silicone polymers can be characterised by the following properties:
• adjustable elasticity and shore-hardness, respectively
• adjustable thermal expansion
• very well stainable characteristics
• increased electrical isolation properties
• decreased contraction during reactio
Due to its world-wide availability, its high hardness and chemical stability quartz is a versatile natural raw material. By water separator technique highly pure SiO2 is separated of its accessory minerals. After the drying process the material is refined to powders of exactly defined properties by extent grinding processes . The calcined form of quartz is the cristobalite which is manufactured in a rotary furnace. It is characterised by a reduced specific density and a very high whiteness.