Volume 41, Issue 4

In the development of new and improved bleach systems for detergents there is a need for a reliable and generally accepted protocol to test colour and fibre damage. We here describe a protocol to screen detergents on colour damage/fading under European wash conditions, using a recently developed set of dyed fabrics. The test protocol has been evaluated in an inter-laboratory test and was found to be robust in the sense that it gave similar results in different laboratories. Hence the protocol described is recommended for testing the colour damage/fading properties of oxidative bleach containing detergents for the European market.

In the development of new and improved bleach systems for laundry detergents there is a need for a reliable and generally accepted protocol to test on fibre damage. Several methods for measurement of damage to cotton are published in the international standards. In an inter-laboratory test some of these methods were applied to cotton that was repeatedly washed with bleach containing laundry detergents. It was found that not all measurements give consistent results. Based on the findings tensile strength loss measurement is regarded as the method of choice for determination of fibre damage by bleach containing detergents.

One goal of optimising cleaning processes is the economic use of surfactant. To find the optimum concentration of active surfactants for a stable and high cleaning quality, a measurement technique to determine this concentration is required, in order to establish a correlation to the cleaning result. The article introduces a modified surface tension measurement method to determine the concentration of active surfactants in process conditions. Based on this method, a new generation of inline tensiometers had been developed. These Instruments allow continuously monitoring the active surfactant concentration in a cleaning bath. The article shows how to interpret the measurement results for the process control. Exemplarily at the use of online measurement in metal cleaning processes, the potential to provide a higher level of process quality control will be illustrated.

Interactions in thin liquid foam films and between solid/liquid surfaces coated with the non-ionic surfactant hexaoxyethylene dodecylether (C 12 E 6 ) were investigated with a TFPB ( thin film pressure balance ) and the MASIF ( Measurement and Analysis of Surface Interaction Forces ) technique, respectively. For foam films the formation of common black films (CBF) and Newton black films (NBF) was observed depending on the surfactant concentration and the applied pressure. With increasing surfactant concentration and increasing pressure the CBF is destabilized, whereas a stabilization of the NBF is observed. In addition, MASIF measurements with two different hydrophobic surfaces were made. In one case silanated glass surfaces and in the other case thiolated gold surfaces were used. Differences and similarities of the interactions between these two surfaces are shown and discussed. Furthermore, the results of the MASIF measurements are compared with the ones of the thin film pressure balance measurements and the influence of the surfactant concentration on the interactions is discussed.

Nano-particles or nanometer-thin layers are well established for permanent modification of hard surfaces. Depending on the physical and chemical properties, such films can lead to anti-scratch, anti-reflective and “self-cleaning” properties. The use of nano-particles and nanometer-thin polymeric films is also of interest for temporary applications. In this work it is shown that application of particle dispersions or polymers on hard ceramic surfaces can lead to distinct self-organization of the nano-particles due to electrostatic repulsion and surface free energy minimization. Some of the resulting semi-permanent surface modifications show reduced contact angles for hydrophilic liquids, which results in long-lasting effects of enhanced drainage, increased drying speed and reduced re-soiling. The self-organization of hydrophilic nano-sized particles with different size and surface characteristics is evaluated compared to polymeric surface modifiers.

The official survey of detergents and cleansing agents includes both: the environmental care by overlooking the regulations of the Washing and Cleaning Act and the consumer protection, which is established in the Food and Consumer Goods Act and the Chemical Law. The work of the official survey was illustrated by example of the analytics and assessment of fragrances in laundry detergents and cleansing agents and the use of limonene as solvent was shown. The results of the examinations were presented.

The phase diagrams at 298.2 K for the systems heptylammonium heptanoate-heptane-water, butylammonium decanoate-butanol-decane-water and butylammonium decanoate-butanol-decane-sodium chloride (aq) have been determined. A large three-phase region and an extensive microemulsion phase were obtained for the heptylammonium heptanoate system. Addition of both cosurfactant and electrolyte brings about a separation into three phases in the butylammonium decanoate-water system. All three-phase systems were characterized by low inter-facial tensions. Sound velocity, conductivity, and viscosity measurements were used successfully for qualitative studies of microstructural transitions in the isotropic microemulsion phase.