What does ZruElast stand - Zrunek

1 At the beginning of the 20th Century the tomer. rubber formulation and compound only elastic material available was Natural development not only requires extensive rubber . Today, designers can choose from expertise and experience, but also appropriate more than twenty different synthetic elas- laboratory facilities and equipment. Figure 1. tomers. This great variety offers outstanding shows the first steps of the rubber formulating flexibility to solve the sealing problems arising procedure. This begins with mixing of the suit- from the numerous and multifaceted require- able raw materials in the laboratory mill. Sub- ments in modern applications. A very special sequently, test pieces are vulcanized and later elastomer is fluoro rubber . In many fields, the measured using our advanced test- properties of this specialty rubber are superior ing and laboratory equipment. to those of other elastic materials. Zrunek Only after the desired results Gummiwaren GmbH specializes in the formu- and values are achieved, lation and mixture of elastomer compounds will the formulation be and focusses in particular on fluoroelastomer- released for pro- based compound development.

2 This class of duction and mix- materials made by Zrunek is referred to as ing-plant out- ZruElast FPM. put. What does ZruElast stand for? ZruElast is a registered trade mark of Zrunek Gummiwaren GmbH. The name ZruElast represents all tested, specified and proven elastic materials made by Zrunek . For more than 50 years, our in- house laboratory has provided complete compound development and testing serv- ices. The laboratory is supervised by Dr. Ulrich Zrunek himself who is a doctorate chemist. Unlike plastics technology, where the ready- : In-house compound development to-process raw materials have to be purchased directly from the chemicals groups, rubber materials first have to be compounded based The Difference between on a formulation. For this process, fillers, plas- ticizers and various other chemicals are added FPM, FKM and Viton . to and mixed with the base polymer ( rubber ). Only the proper combination of these raw The terms FPM, FKM and Viton very often materials results in the desired properties cause confusion and lead to incorrect interpre- which are expected of the developed elas- 2.

3 Tations. All of these designations actually stand and exposure to chemical media. In addition, for one single base material:fluoro rubber . parameters such as specific mechanical requirements for static and dynamic applica- FPM is the international abbreviation tions, electrical properties, hardness, colours according to DIN/ISO, whereas FKM is the or flammability should be taken into considera- short form for the fluoroelastomer category tion. according to the American standard ASTM. Viton is the registered trade mark of DuPont As a result of the complexity and great num- Dow- Elastomers. Zrunek uses the designation ber of factors there is a simple rule for design- FPM for all of its fluoro-elastomer materials. ers derived from practical experience: Designing with Elastomers If possible, try to cut down the design requirements to those 'absolute neces- sary' and try to avoid demands such as Elastomers are not usually materials design- 'would like to have' or other arbitrary ers are overly familiar with, nor do they deal demands.

4 With them day-to-day. In general, metals and their individual specifications are the materials which designers have in mind when designing and these influence their thinking at a basic Advantages of ZruElast FPM. level. Therefore, parts often are designed with- out considering that the material-specific prop- ZruElast FPM are materials based on flu- erties of metals can meet other requirements oroelastomers. These materials offer one of than those of elastomers. This difference may the highest resistances to heat and chemical compromise the correct selection of a suitable media of all elastomers ever developed. They elastomer. withstand hundreds of fluids, from ordinary to most aggressive, over a wide temperature In order to select a proper elastomer it is range. Additionally, they retain reliable and necessary to define the specific demands of leakage free sealing force in situations where an application. This includes a full description ordinary elastomers would long have failed of the conditions in use and full details con- cerning exposure to any chemical media, ther- Fluoroelastomers do not come cheap.

5 This mal resistance requirements, compression is why they primarily were used only for small load, mechanical stresses as well as informa- parts in environments where in contact with hot tion about time-related factors. and corrosive fluids. Today, however, as a result of higher energy costs, stringent envi- Particular attention should be turned to the ronmental regulations, extended warranties media with which the elastomer is in contact. and increasing maintenance costs, many These media should not affect the sealing users have reconsidered and now think of material, nor should the media be affected by ZruElast FPM as a cost-effective material, the seal. Furthermore, the lifetime and durabili- especially when taking into regard the com- ty of a seal can be very critical factors. These plete lifetime of a product. very often are directly linked to temperature 3. The Exceptional Strengths Abb. 3: Swell resistance of ZruElast FPM.

6 Examples (Compound 7575 und 7009 ). of ZruElast FPM. Temperature Resistance Fluoropolymers in general feature excellent heat resistance. ZruElast FPM retains its elastic properties even at a continuous operat- ing temperature of 200 C. When talking about temperature resistance, it has to be considered for how long materials are exposed to heat or elevated temperatures. Figure 2 shows the relation between operating temperature and hours of use. Besides the ability to withstand short blasts of more than 300 C, laboratory tests have confirmed that products made of ZruElast FPM still remained soft and elastic even after ageing in a heat cabinet over a peri- od of three years at a temperature of 190 C. If you compare these values with the perform- ance of other elastomers they seem even more significant. Nitrile rubber (NBR), for example, usefully serves only up to a continuous maxi- mum temperature of 120 C. Fig.

7 2: Heat resistance of ZruElast FPM in air 4. Similar in temperature performance are the ing the relation between temperature and vol- materials chloroprene (CR) and chlorosulfonat- ume swell in several examples. ed polyethylene. Aged at a temperature of 200 . C, products made of these materials would In sealing technology, in particular in engine become brittle only after a few hours. construction and hydraulics, oil resistance combined with exposure to heat plays a funda- Swell Resistance mental role. Figure 4 shows the resistance to heat and volume swell of ZruElast FPM in The excellent swell behaviour of fluoroelas- comparison with other common elastomers. As tomers has already been tested in a number of you can easily see, only Kalrez , an extremely important media, for example mineral oils, expensive perfluoroelastomer, delivers better fuels, acids, bases, solvents, and numerous performance. All other commercially processed chemicals.

8 Figure 3 on the previous page elastomers neither achieve the thermal stabili- gives you a short overview of the outstanding ty of ZruElast FPM nor feature the same low volume swell resistance of ZruElast FPM.. volume swell characteristics. Zrunek has compiled a chemical resistance guide which will give you extensive information This outstanding resistance to swell com- about the swell behaviour of ZruElast FPM bined with exposure to heat makes ZruElast FPM in a number of chemical media. You also FPM the most universal sealing material of all will find additional technical data demonstrat- commercial elastomers. : Heat and oil resistance of ZruElast FPM in comparison with other elastomers 5. Long-Term Retention of importance when designing long-life, high- Sealing Force quality machines, where absolute product reli- ability is demanded, when high guarantees are Resistance to compression set is another required or when the risks of causing environ- very important physical property in sealing mental damage due to seal failure or leakage technology.

9 The lower the compression set become incalculable values, the better the sealing force and ability to recover from applied deformation. In combi- Low Temperature Resistance nation with exposure to high temperatures, ZruElast FPM further shows its superior Experience has shown that seals made of compression set properties. Without any prob- FPM in dynamic applications usefully serve at lems values of 8% at 200 C can be achieved. temperatures down to approx. -20 C. In static use they even can work at temperatures down ZruElast FPM is also unbeatable when it to -40 C. Furthermore, experience has shown comes to sealing force over a longer period. that the more thin-walled parts are, the lower As illustrated in figure 5, all other common the operating temperature at which they can elastomers fail long before. After 100 hours of work. The same effect occurs when the seal is use in static application in air at 150 C Zru- continuously in contact with a medium that Elast FPM retains 91% of its original sealing causes slight swell.

10 This improves the low tem- force, while silicone, acrylate and nitrile rubber perature flexibility and allows use at even low- with 69%, 56% and 38% show values well er temperatures. below. After 10,000 hours of service time at last only FPM provides sufficient sealing force Flame Retardance (70%) These characteristics are of special ZruElast FPM is based upon fluorocarbon elastomers. The chemical bond of fluorine to Fig. 5: Long-term sealing force of ZruElast FPM in comparison with other elastomers carbon is extremely strong. Thus, under condi- tions of fire, its resistance to breaking and damage exceeds that of all other hydrocarbon elastomers. Use in Vacuum ZruElast FPM contains no plasticizers and thus exhibits very low outgassing in use under extreme vacu- um conditions. Loss of weight of only 2-3 % in vacu- um applications is typical for this material. Therefore Zru- Elast FPM is the ideally 6. suited material for seals requiring absolute ozone has no effect on ZruElast FPM.