Bleach systems to deliver hygiene benefits in laundry detergents

Governments and the World Health Organization have released a variety of guidelines and recommendations to manage, control and reduce the spread of diseases. The most basic protection usually involves frequent hand washing with soap and water or using alcohol-based hand rub. However, disinfecting clothes, linens and washing machines can also help reduce possible spread of germs and ensure hygiene in the home.

Historically, laundry detergents have been employed to clean clothing and domestic household items, primarily to remove specific stains from the laundry wash load. Yet dirt and microbes can contaminate textiles.

Clothing and linen are a risk factor for transmission of infections and illnesses. The spread of diseases via soiled clothing, as well as malodour issues, can be prevented through the use of laundry detergents with antimicrobial efficacy.

Over recent years several changes have occurred in the laundry detergent market which have in turn driven changes in consumer washing practises. The heating of water in the washing machine cycle is widely recognised as the activity that consumes the most energy. To address the needs of sustainability, consumers are advised to wash at lower wash temperatures to deliver energy savings. Additionally, the amount of water used in a wash cycle has decreased over the last 20 years.

A study by Lubrizol Advanced Materials demonstrates that the use of tetraacetylethylenediamine (TAED) in combination with sodium percarbonate (PCS) can deliver effective hygiene performance benefits and compensate for the loss of hygiene effectiveness of washing at lower temperatures.

Discussion and results

Within a laundry detergent formulation, a bleach system is primarily employed for the removal of coloured bleachable stains through the oxidation of stains either on a fabric surface or in the wash liquor. In addition to stain removal and maintaining the colour of white textiles, the bleach system also provides the functions of ensuring fabric and machine hygiene. The most wellestablished laundry bleach system is the bleach activator TAED (tetra acetyl ethylene diamine) which is used in conjunction with sodium percarbonate (PCS) to form peracetic acid (PAAH) shown in the reaction in Figure 1.

PAAH generated from the PCS/TAED contained in powder detergent formulations is responsible for low temperature bleaching and broad-spectrum biocidal performance ensuring both the washing machine and laundered fabrics are hygienically clean ¹ . The hygiene benefit delivered through the bleach system is now becoming increasingly important, particularly under conditions of high soil loading and as high temperature washing is now less frequent, preventing thermal disinfection.

Many washing machines also have the option of quick wash cycles, which include a reduced length of main wash time and result in reduced exposure to the biocidal effect of detergent and temperature 2 .

In the absence of a bleach system, ineffective control of microorganisms on fabrics can potentially cause health problems for society’s most vulnerable, including young children, the elderly and people with compromised immune systems 2 .

Testing has shown that in the absence of bleach a reduced kill of microorganisms is delivered – illustrated in the ASTM HE laundry test E2406-09 (see Figure 2). Results show detergent alone fails to pass the ASTM test (49g detergent with 12 minutes contact time at 30°C), which requires a Log 3 reduction in bacteria to be achieved. However, the addition of TAED/ PCS to deliver 150ppm PAAH clearly passes the ASTM E2406-09 test.