3.7 Detergents Modern detergents are less aggressive than those used in the past, partly for reasons of environmental protection and partly to prevent damaging the fibres. If used correctly, these offer an excellent protective treatment and a high level of washing power. Detergents that contain no phosphates are far more sensitive to the reaction with calcium. When the door of a washing machine is opened, the user will immediately observe that the interior is clean and shiny if high- quality detergents have been used.
3.7.1 Composition of a detergent ѓ SURFACE-ACTIVE AGENTS (soap and active washing substances) ѓ ZEOLITES (water softeners) ѓ ALKALIS ѓ BLEACHING AGENTS ѓ OPTICAL WHITENERS ѓ OTHERS: Enzymes, stabilizing agents, CMC, colouring agents, perfumed essences, TAED, PVP, lipase, protease. 3.7.2 Functions of the principal components of a detergent 1. SOAP: A detergent that is soluble in water, composed of sodium or potassium salts, fatty acids (such as oleic or stearic). The main function of soap is to dissolve grease.
During the washing cycle, the grease precipitates, creating insoluble calcium (Ca) and magnesium (Mg) salts which, if present in excessive quantities, tend to become attached to the fabrics (black balls). 2. SURFACE-ACTIVE AGENTS: synthetic substances with wetting and detergent properties, and able to reduce the surface tension thus facilitating the penetration of the washing solution into the fabrics to dissolve the dirt. These agents disperse and emulsify the dirt and grease, which are then held in suspension in the washing solution. 3. SILICATES: alkaline substances that improve the washing result, protecting the fabrics or dishes and the appliance itself from corrosion.
Not aggressive to the skin. 4. ANTI-FOAM (regulator): the correct quantity of foam is necessary for the effectiveness of the mechanical action, and therefore influences the intensity of the wash (large quantities of foam reduce the mechanical action and vice versa). Anionic surface-active agents generally increase the quantity of foam. 5. ZEOLITES: Zeolite is an insoluble solid that absorbs or fixes calcium ions, replacing them with sodium ions (to reduce hardness), thus increasing the effectiveness of the detergent. 6. ALKALIS: alkalis make the washing solution alkaline, increasing the washing power and swelling the fibres so that the dirt is dissolved more easily.
In addition, alkalis help to remove scale build-up from the appliance. 7. BLEACHES: bleaches are generally perborates (substances that generate active oxygen). Active oxygen is released during the washing phase between 60°C and 90°C, and requires the presence of stabilizers to ensure uniform action. The oxidizing power of the active oxygen released eliminates substances that stain the fibres. 8. OPTIC WHITENERS (also known as blueing agents): optic whiteners are organic chemical substances that can transform ultraviolet light into visible "BLUE" light (yellow + blue = white). SOI/DT 2006-03 dmm 13/70 599 37 67-82