Hydrogen peroxide for color safe bleaching
The use of hydrogen peroxide allows not only a high degree of brightness, but also preserves the mechanical properties of the fibers. Similar to pulp bleaching, this process takes place in an alkaline environment. The bleaching liquors have to be stabilized to prevent decomposition reactions due to the presence of trace metals such as copper, iron and manganese, which can often be found in fibers or in water.
Cotton is the main fiber bleached today. Practically all cotton produces nowadays is bleached. About 80-90% of all cotton fabrics are bleached with hydrogen peroxide. Typically, bleaching with 0.3-0.6wt% solutions of H2O2 at a pH of 10.5-11.5 is carried out for 1-3 hours at a temperature of 90-95 °C. In the past, sodium hypochlorite was commonly used for cotton bleaching. Hypochlorite bleach was, however, abandoned because of high fiber damage and technical difficulties.
Color safe laundry bleaches containing hydrogen peroxide have been accepted by consumers as alternatives to bleaches containing hypochlorite. One of its advantages over chlorine-based bleaches is that it does not affect modern dyes. Evonik’s hydrogen peroxide grades were proven to yield an excellent bleaching performance in hard surface cleaners, laundry prespot products, carpet cleaners, and other color safe bleaching products.
Peracetic acid based laundry disinfection and bleaching process
Since peracetic acid is a sustainable and skin friendly chemical, it is suitable for disinfection and as a bleaching agent for industrial laundries. Especially workwear and hospital uniforms which have permanent contact with the skin during the day, skin friendliness needs to be taken into consideration when chosing the right disinfecting agent.
Industrial laundries process laundry from hotels, hospitals, restaurants, and food processing plants in continuous-flow washing machines. These washes consist of a series of different compartments in which the linen is treated. The process consists of pre-washing, washing, rinsing, post-treatment, and dewatering.
In the chemo-thermal disinfection of laundry, especially originating from medical institutions and nursing homes, PAA and H2O2 are used in the washing stage as a disinfectant and bleaching agent. Preventing possible pathogen transfer among patients is the primary goal of laundry treatment. Disinfectants are usually added in the main wash cycle and target the elimination
of spores and viruses. Sometimes, the disinfection step is carried out after applying detergents and prior to the dewatering cycle. Textile disinfection is essential for infection prophylaxis for patients and staff in numerous medical facilities.
Our Products for Laundry and Textile Hygiene
For textile and color safe bleaching Evonik recommends using HYPROX® hydrogen peroxide products. For specific requirements we can recommend further grades on request.
For chemo-thermal laundry disinfection, PERACLEAN® peracetic acid products are used in the washing phase as disinfectants and bleaching agents. The high H2O2 concentration in PERACLEAN® provides the desired bleaching effect. The advantageous ratio of peracetic acid to H2O2 has a positive effect on the stability of peracetic acid in the wash liquid and in some cases allows the amount of disinfectant added to be reduced while maintaining a good bleaching effect.
Disinfectants with a medical use are biocidal products and are subject to the BPR. These are general-purpose disinfectants for rooms, hard surfaces, devices, and hands, as well as disinfection of hospital laundry. CLARMARIN® 350 hydrogen peroxide is a registered biocide in the European Union for chemo-thermal laundry disinfection. Please contact us for further information.