THE MODERN HYGIENIC AND FRESH FINISH BASED ON SILVER
The requirements of textiles regarding hygiene and freshness have increased. The antimicrobial effect of silver, which has been known for centuries, can be used for innovations. Especially textiles worn next to the skin offer the ideal biosphere for microorganisms, such as bacteria. They transform the organic content of body moisture into degradation products of unpleasant odour. The antimicrobial effects of silver inhibit this odour formation. Silver ions on textiles are more efficient by far than other antimicrobial technologies without affecting the skin.
The antimicrobial effects of silver have been known for centuries. In early modern times silver coins were placed in earthen vessels to protect milk from bacteria and to preserve it. Today the inside of refrigerators is made of silver-containing coatings to meet hygienic requirements. Through silver, enamels and ceramics obtain an antimicrobial function too. In the field of medicine silver found usage a long time ago as a therapeutic agent in wound care, on medico-technical plastics or in the treatment of atopic dermatitis.
Silver on textiles
The requirements of textiles regarding hygiene and freshness have increased in the past few years. Thus, it has only been a question of time until silver has found its field of application. Especially textiles worn next to the skin, such as underwear, socks and sports shirts, offer an ideal biosphere for microorganisms like bacteria. For existing, they require certain conditions, such as:
- (Body) heat
- (Body) moisture
- Large surface areas (textiles, skin)
- Food, eg soil particles
Bacteria exploit the organic content of the body moisture generated. The degradation products of this exploitation are associated with unpleasant odours. The antimicrobial effects of silver in the form of silver ions on textiles inhibit this odour formation. Silver (respectively silver ions) is the antimicrobial active ingredient of the SILVERPLUS® hygiene and freshness technology.
Triple mechanism of silver (graphic: Rudolf GmbH, Geretsried)
The antimicrobial effects of silver
The antimicrobial effect is described by means of a triple mechanism of silver ions directly on textile surfaces. The further formation and uninhibited multiplication of bacteria in textiles is prevented as follows:
- Stopping the oxygen supply by blocking oxygen-transporting enzymes
- Stopping the multiplication of bacteria by inactivating sulphur-containing bacterial proteins
- Stopping the nutrient supply by blocking the cell membrane
No formation of bacteria resistance
Bacteria are directly controlled on the textile surface by antimicrobially active SILVERPLUS® silver ions. The triple mechanism of silver ions prevents the formation of adapted bacteria. According to current observations, bacteria are not able to adapt to all three mechanisms to become resistant to silver.
How does SILVERPLUS® work?
SILVERPLUS® is based on micro-structured titanium dioxide as a carrier of the active component silver chloride. In the presence of moisture (eg perspiration), only the quantity of antimicrobial silver ions from a virtually infinite deposit are released that is needed for preventing bacterial growth. This highly efficient mode of action is called “flexible response”.
Silver ions are more effective by far than other antimicrobial technologies. Due to its large active surface and high efficiency the active component SILVERPLUS® is effective at very low and thus economic application quantities.
How can the hygienic effect of SILVERPLUS® be assessed?
-
Suitable lab test method
The antimicrobial effect of silver ions is non-migrating, which means that it is effective on the textile and does not form inhibition zones according to the Agar Diffusion Plate Test (SN 195 920).
The “Dynamic Shake Flask” test method according to ASTM-A2149-01 is the best lab test method for demonstrating the antimicrobial effect of SILVERPLUS®. This test method imitates the wearing of textiles. The contact between antimicrobially finished textiles and bacteria in a bacterial suspension is ensured by mechanical shaking. The antimicrobial active ingredient does hence not necessarily migrate out of the substrate. The full antimicrobial effect of SILVERPLUS® is normally attained after a dwell time of 24 hours.
-
Wear test
Lab test methods try to imitate reality, often with only mediocre success, but enormous expenditure. Certain test methods illustrate certain effective principles of the products. Hence, the experience made during wearing is the best method by far to experience the mode of action of SILVERPLUS®.
Advantages for end-users
-
Excellent resistance to washing and dry cleaning
Due to its micro-pigments SILVERPLUS® can anchor to textiles in a resistant-to-washing and dry-cleaning manner without binder or adhesive systems that inhibit moisture transportation or affect the handle. SILVERPLUS® embeds in the fibre interstices and is permanently bonded by strong adhesion forces.
This process is comparable with embedding soot particles, which, even after repeated wash cycles, cannot be removed with commercial scouring agents. Usually, the result are highly wash-resistant properties that, at higher application quantities (~ 4 – 5 g/l RUCO-BAC AGP), withstand more than 100 coloured laundries at 60 °C, which has been confirmed by independent test institutes.
-
Synergism of hygiene management and optimised moisture transportation
In combination with moisture-transportation-improving, hydrophilic-rendering RUDOLF agents further optimised functional properties regarding moisture management are conferred to textiles. Better perspiration transportation away from the body onto the textile. SILVERPLUS® controls bacteria on the textile instead of on the skin.
-
No influence on the natural balance of the skin
Many products with antimicrobial effects may migrate from the textile onto the skin and are suspected to attack it. SILVERPLUS® develops its antimicrobial effects exclusively on the textile surface. The hygienic effect develops only on the textile, but not on the skin. Thus textiles finished with SILVERPLUS® protect against the spreading of health-hazardous bacteria without attacking those having a positive effect on the skin. This has been confirmed by the independent test institute ITV Denkendorf by means of a cytotoxicity test with fibroblasts (DITF method KV 01, 2002: testing the body tolerance of textiles; DITF method TOX 04, 2002: testing the cytotoxicity: MTT test) on 100 % CO wovens finished with RUCO-BAC AGP.
-
Hygienically clean textiles even at 40 °C
Many textiles can only be washed at 40 °C (amongst other things textiles made from viscose). The trend towards environmentally friendly 40 °C laundries is unbroken. However, at 40 °C the washing machine is an ideal breeding ground for bacteria. Bacterial growth is optimally supported at this temperature, which becomes evident, above all, by the musty odour when drying laundry in poorly ventilated cellar rooms or in areas with high humidity. SILVERPLUS® confers hygiene and freshness to textiles at 40 °C. The consumer thus saves money and energy.
-
Hygiene and freshness for more textile comfort with Oeko-Tex Standard 100
The high-performance version RUCO-BAC AGP has been registered on the Oeko-Tex list and thus complies with Oeko-Tex Standard 100. After testing textiles finished with RUCO-BAC AGP can be certified according to Oeko-Tex Standard 100. In addition, the antimicrobial active ingredient of the SILVERPLUS® hygiene technology is FDA1 and EPA2-registered.
Further cost and technical application advantages through SILVERPLUS®
-
Easy application results in optimised costs/efficiency
Normally, the costs of finishing textiles are not caused by the finishing product, but by additional process steps due to its application. SILVERPLUS® can be integrated in any step of textile finishing; a separate run, as with many conventional antimicrobial systems, is not necessary. A sales-promotional, functional additional value is created. From an economic point of view SILVERPLUS® is profitable.
-
An additional binder system is not necessary
The use of a binder/adhesive system for heat-setting SILVERPLUS® in a resistant-to-washing and dry-cleaning manner is not necessary. Binder/adhesive systems, as offered for other silver-based product systems, have the following disadvantages:
- Limited application variety, mostly only by padding
- Binder systems require higher curing temperatures, possible changes of white shades or colour
- Separate run under curing conditions, which increases production costs
- Limited compatibility with other finishing agents
For obtaining hygienic effects ordinary drying is sufficient to embed SILVERPLUS® in the fibre interstices. Depending on the combination with other finishing variants or process steps in dyeing or finishing, curing/setting temperatures can be used without effect losses.
-
Good compatibility with other functional finishes
SILVERPLUS® can be excellently combined with the following functional finishes:
Hydrophilic finishes
The existing or created hydrophilic properties of fabrics are not affected by SILVERPLUS®. With SILURAN® “total wear comfort” is ensured.Hydrophobic finishes
In combination with water, oil and soil-repellent finishes (®RUCO-GUARD, ®BIONIC-FINISH) these textile surfaces are additionally protected against bacteria. The water and oil repellency are not affected.Soft-handle finish
SILVERPLUS® is extremely suitable for a combination with RUDOLF softeners of the type ®RUCOFIN or ®PERRUSTOL and does not at all impair the textile handle.
Summary
SILVERPLUS® has made the hygienic effects of silver, which have been known for centuries, a universal top-finish technology. In the meantime, the numerous advantages of the SILVERPLUS® hygiene and freshness technology have become established in the world market. You will find extensive technical information about SILVERPLUS® on the RUDOLF home page www.silverplus.com.
