Antibacterial properties have long been a topic of interest in the ceramic industry but for obvious reasons have now become a particularly important area of research. It is a complex field with a potentially wide range of different solutions. While many substances are capable of giving surfaces antibacterial properties, only two of them (each with different action mechanisms) are currently being taken into consideration in the ceramic sector: silver and titanium dioxide.
The Zschimmer & Schwarz Ceramco laboratories have been conducting research in this field for some time now and have recently developed a variety of solutions capable of meeting the urgent and increasingly diversified needs of the market. These different needs in turn derive from the specific production contexts of the companies in the sector, including the types of systems and raw materials they use and the collections they produce.
This wide range of solutions reflects a general principle that is particularly relevant to the field of antibacterial surfaces: it is impossible to create a universal product suitable for all applications.
THE ZSCHIMMER & SCHWARZ APPROACH
The approach adopted by Z&S Ceramco focused on the use of active ingredients based on liquid colloidal silver, either in the metallic state or in the form of a chemical compound. This type of silver has the ability to act on pathogens through direct contact, attaching itself in the form of granules to the surface of bacteria and thereby damaging their cell walls. By inhibiting the key physiological functions of microbial cells, silver ions interfere with their vital enzymes, blocking respiration, breaking down the cellular membranes and halting the DNA duplication mechanism that is essential for bacteria to proliferate.
While awaiting future research developments, the proposed application solutions can currently be divided into two broad categories.
Firstly, post-firing applications which involve adding the medium to products intended for post-lapping anti-stain treatment.
Secondly, pre-firing applications which are divided up as follows:
- Insertion of the medium into the raw glaze before it is applied to the substrate;
- Application of the medium onto the glaze by means of a spray gun (top glaze) as the final step before firing;
- Insertion of the medium into the ink and subsequent application onto the raw glaze using a digital printer.
The Polishield range, already used by a number of companies in the sector to improve stain resistance, has been expanded with the addition of a corresponding series of functionalised versions called POLISHIELD AF. Each product has a different formulation according to the final finish of the material (natural or mirror lapped, polished, etc.) and the polishing machines used. By undergoing a process of crosslinking inside the open pores without altering the aesthetic qualities of the ceramic material, the product can be used on an “as-is” basis (by means of a rotary roller, dripping system or sponge applicator) and distributed by means of two or three planetary brushing machines. The medium can also be pre-diluted in water if the application is to be performed using multi-head systems (which involve a greater number of rotating heads and therefore a larger number of applications in sequence).
The functionalised products in the LEGOCER AF range are available as readily soluble concentrated binders suitable for top glazes and intended for use as the final application onto the ceramic substrate prior to firing. Along with their important sanitising properties, they also give the glaze greater mechanical strength. The same product (but only in the case of tiles with a natural surface leaving the kiln) can be diluted in water and applied to the surface after glazing.
For both types of products, the dosages and duration of the treatments vary according to the surface characteristics, the method of application and the effectiveness of the treatments, so the producers and suppliers must work together to determine the best solution according to the objectives and product specifications.
We invite you to contact the company for lab tests.
THE RANGE (work in progress)
POLISHIELD AF 364
POLISHIELD AF 375
POLISHIELD AF 405
POLISHIELD AF 2450
LEGOCER AF 005
LEGOCER AF 015
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