28 Nov Technical fabrics – Part 1
With this page, we begin a series of technical publications dealing with basic weaving theory, applied to liquid filtration. In this case, we will talk about the different fibre compositions we work with at Finsa. In turn, how this characteristic can make the difference between the suitability, or not, of a filter fabric in any process related to this field.
The main fibre compositions worked in Finsa – JOB | Group are Polyester (PES), Polypropylene (PP) and Polyamide (PA); for the latter, we also include the most frequently used variations of this polymer: polyamide 6, polyamide 6.6, polyamide 11 and polyamide 12. As mentioned above, the choice of one fibre or another will have direct consequences on the performance of the product in terms of mechanical and chemical resistance and even cake discharge (a basic parameter that can be evaluated for filter press cloths).
This thermoplastic polymer has the ideal characteristics for a large number of liquid filtration applications. Fibres of this composition are used for filtration processes in mining (alumina, cobalt, copper, gold, etc.), beer, wine, sugar production and even for wastewater treatment, among others.
It is thanks to its properties, as we have mentioned, that it is a material with a large presence in so many liquid filtration applications. Firstly, it has a low density (0.90 kg/dm³) which makes products of this composition very light and malleable. It also has an acceptable heat resistance, being able to work in temperatures of up to 90-100ºC (discontinuous work). Even so, the main characteristic compared to the other two polymers mentioned is its chemical resistance, being able to work at all pH levels. On the other hand, it has very little resistance to oxidising agents (or halogens).
Polyester composite fibres, although less used than the previous fibres, are prepared to work in liquid filtration processes for the mining industry (anthracite and coal), the production of kaolin, clays, oils and fats, silicas, dyes and pigments, and even for the production of caragenates (Agar-Agar).
These fibres are characterised by their excellent heat resistance, being able to withstand maximum working temperatures of 130-160ºC (discontinuous work). Compared to the previous case, polyester has a higher density, with a value of 1.38 kg/dm³. It also has a low moisture absorption, which allows it to dry very quickly, retaining a minimum amount of water in the pores of the fabric. Finally, where it does show less durability is when working in a basic environment; its chemical resistance is concentrated, and shows its highest values, in acidic environments and against oxidising agents (or halogens).
Finally, we find the set of polyamide fibres. Including all the variations commonly used at Finsa, these fibres are used in filtration processes in the mining industry (alumina, coal, lignite, aggregates, etc.) as well as for the production of kaolin, clays, granites and marbles, among other applications in this sector.
In the case of polyamides, as mentioned above, we frequently use 4 variations: polyamides 6, 6.6, 12 and 11. Although they are different variations of the same polymer, certain common properties can be summarised. The main characteristic of this polymer, compared to the other two presented, is that it has the highest maximum working temperatures, reaching values of up to 180-220ºC (discontinuous work). They also have excellent abrasion resistance, as well as good sliding properties. On the other hand, they have high moisture absorption and low dimensional stability. Finally, it should be noted that polyamides do not have good chemical resistance to acids and oxidising agents, working best in basic environments (alkalis).
To conclude on this subject, at Finsa we work with a large number of fibres of different compositions, each with its advantages and disadvantages. In this way, we are prepared to provide any industry that has a filtration process with any of our filter fabrics to improve these processes.
If you think that Finsa can help you in your filtration processes, do not hesitate to contact us.
We will be pleased to help you!