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Laundry Agents


There are only a few major types of laundry agents:

  • Detergents (Which is a major group)

  • Alkali

  • Bleaches

  • Anti Chlors

  • Sour/Acid Agent

  • Fabric Conditioner

  • Optical Brightener

  • Starch

1. Detergents

Strictly speaking, the term detergent can be applied to any cleaning agent. Its usage is known generally restricted to those cleaning agents containing significant quantities of a group of chemicals known as surfactants. A number of other chemicals are frequently included to produce a detergent suitable for a specific use.

Essential properties

A good detergent will possess many or all of the following properties:

  1. Reduce the surface tension of water so that the cleaning solution can penetrate the soil and surface.

  2. Emulsify soil and lift it from a surface.

  3. Suspend soil in the cleaning solution

  4. Be soluble in cold water

  5. Be effective in hard water

  6. Be harmless to user and surface to be cleaned

  7. Rinse easily to leave no streaks or scum

  8. Be economical in use.

Chemical composition

Detergents are formulated from the types of chemicals described in the following:

a. Surface active agents (surfactants) are chemicals, the molecules of which when dissolved in water possess a water-seeking (hydrophilic) end and a water-repelling (hydrophobic) end. They may or may not carry a negative or positive electrical charge. The molecules are dispersed through the water so that they reduce the surface tension of the water by overcoming the forces of attraction between the water molecules, thus allowing the water and surfactant molecules to penetrate the soil and surface. The hydrophobic ends of the surfactant molecules are attracted to the soil, surrounding particulate soil particles and lifting them from the surface while breaking and rolling up grease into small particles and lifting them from the surface. The hydrophilic ends of the surfactant molecules point out from the soil particles into the surrounding water. As individual particles approach each other the hydrophilic parts of the surfactant molecules on different particles repel each other keeping the soil in suspension and preventing it from settling back onto the surface.

b. Builders are alkaline chemicals that influence the effectiveness of cleaning agents in one or both of the following two ways:

  • They sequester (combine with) calcium ions in hard water to form water-soluble salts, thus preventing the adverse effects of calcium.

  • Enhance the emulsifying and dispersing properties of the detergent.

Complex phosphates e.g. Sodium Tripolyphosphate, are included in many detergents powders and act in both of the ways described. Sodium metasilicate and sodium carbonate are included in many liquid detergents and function in the second of the ways described Builders, in general, can have damaging effects on many surfaces e.g. chrome, aluminium, wool, silk, paints, wood and linoleum.

c. Water softeners are frequently comprised of complex phosphates e.g. Sodium hexametaphosphate because of their sequestering properties.

d. Foaming Agents Increase or stabilize the foam formed by a detergent. Foaming can be used to indicate surfactant activity, the level of foam is dependent on the amount of surfactant active in a cleaning solution. Alkalonamides derived from coconuts oil are frequently used for this purpose. Other foaming agents can be used to produce stable, relatively thick foams in which the other chemicals are dispersed. The foam will stick to the non-horizontal surface and the cleaning chemicals.

e. Chelating agents are relatively complex chemicals which are included in many liquid detergents to sequester calcium ion. In simple terms, a combination of sodium carbonate or metasilicate and a chelating agent will have a similar effect to tripolyphosphate alone. Tripolyphosphate is not normally included in a liquid detergent because it tends to break down in an alkaline solution. Chelating agents are now frequently used as descaling agents, being a more acceptable alternative to strong acids. Suspending agents e.g. Sodium carboxymethyl cellulose (CMS), increase the amount of soil that can be held in suspension in the cleaning solution.

f. Bleaches will break down by oxidation, stains that have not been removed from a surface by surfactants or builders. Sodium perborate, weak bleach is included in detergents intended for washing textile. Bulking Agents Eg:- Sodium sulphate, contribute to the volume of detergent powders Conditioning Agents Ensure that the granules in detergent powders are crisp firm and dry

g. Whiteners: Absorb ultraviolet light and transmit it as visible white light. The whiteness of a surface will normally depend on the amount of natural light reflected from it and received by the eye. Whiteners, therefore, increase the amount of light received by the eye.

h. Enzymes are complex proteins that will break down organic substances e.g. bloodstains, adhering to a surface. They are most effective at 30-50 ̊C and are inactivated at temperatures above 60 ̊C Anticorrosive Agents Inhibit the formation of water films on a surface. Chemical reactions resulting in corrosion are generally dependent on the presence of water

i. Perfumes and dyes are included to increase consumer acceptability but increase the risk of allergic reaction.

j. Suspending Agent

  • The role of the suspending agent in cleaning is to hold the dirt in suspension and prevent it from re-depositing onto the surface of the article.

  • It plays a crucial role in the laundry agent due to the amount of time that the clothes rotation in the machine while the dirt is in suspension.

  • The suspending agent is carboxymethylcellulose.

k. Sequestering Agent

  • Theseactalongwiththesuspendingagenttoholddirtinsuspension.Theyassistby holding a greater amount of dirt in suspension thereby reducing the likelihood of re-deposition.

  • They also have the additional ability to dissolve lime salts that are responsible for temporary hardness in water.

  • Sodium polyphosphates act as sequestering agents.

2. Alkali

Alkalis used in the wash process include 1. Washing Soda (sodium Carbonate Na2CO310H2O) 2. Sodium Phosphate 3. Sodium Hydroxide 4. Sodium Metasilicate 5. Borax (Na2B4O710H2O) 6. Ammonium hydroxide (NH4OH)

The role of the alkali in the wash process

  • Combines with calcium ions in hard water to form water-soluble salts, thus preventing the adverse effects of calcium

  • Enhance the emulsifying and dispersing properties of the detergents

3. Bleaches

  • These are used on white articles only.

  • They remove colouring matter by their oxidizing or reducing action.

  • If not in liquid form, they should be dissolved in hot water in order to ensure that no powder residue remains in the washing machine which may affect later loads.

  • The bleaches commonly used in the laundry process are sodium perborate and sodium hypochlorite (Javelle water).

OXIDISING BLEACH

REDUCING BLEACH

Chlorine bleach

Oxygen Bleach

Oxidising bleach which liberates the oxygen from Bleach

Reducing bleach which reduces the level of oxygen

It is stronger

It is milder

It goes well with cold water

It goes well with hot water

It removes all types of stains, except animal

It is basically used on animal stains

Sodium hypochlorite (Javelle Water) (NaOCl)

Sodium Perborate (NaBO2H2O23H2) Sodium Chlorite (NaClO2) Potassium permanganate (KMnO4) Bleaching Powder (CaOCl)

Sodium Hydrosulphite (Na2S2O4) Sodium Bisulphite, Sulphurous acid (HSO3)

4. Antichlors

These are agents used to neutralize the chlorine bleach and are essential particularly in the case of polyesters. The use of chlorinated bleaches has a tendency to leave yellow deposits.

5. Sour/acid agents

  • Thisisusedonlyinindustriallaunderinginthefinalrinse, to neutralize any alkaline soap residues that may be present.

  • It brings the pH of the linen articles to a level between 5 and 6.5, which is agreeable to the human skin and also gets rid of yellow or brown deposits caused by residue alkali.

  • Acetic acid is used as the sour.

  • In cases where there is a high iron content in the water, Oxalic acid is used which

  • serves a dual purpose, by also getting rid of the reddish, iron deposits.

  • If starch is being used, sour should be added 2 minutes before the starch to achieve a pH of 5.0 to 5.5. If a sizing agent is being used, the ideal pH is 7.0 to 8.0 so sour is generally not used.

a. Oxalic Acid

  • Sold in white crystals

  • Used for removal of fruit stains, bleaching of brown stains after using potassium permanganate and tannin base of ink stains together with Hydrogen peroxide.

b. Salt of lemon

  • Salt of Sorrel

  • Compound of Potassium Oxalate and Oxalic Acid referred as Potassium binoxalate

  • Used for neutralizing strong alkali.

c. Acetic Acid: Removes excessive bluing agents and as neutralising agents

d. Oleic Acid

  • Unsuitable for coloured fabrics.

  • Produces soap when mixed with alkali

  • Used for grease and oil stain

e. Fabric conditioner/Softener

  • A fabric conditioner or softener has surface-active agents like a detergent but they don’t perform the function of cleaning.

  • Fabric conditioners are based on cationic surface-active agents, carrying a positive charge and creates anti-static properties.

  • A fabric conditioner is never used on loads where starch or sizing will be used.

  • The role of the fabric conditioner in laundering

6. Optical brightener

  • This is an optical brightener/ whitener, which is, in fact, a very fine dye, which gets bleached in course of time.

  • It has a fluorescent effect by reflecting the UV rays of the sun.

The laundry blue in a powder form tends to accumulate in the weave of the fabric and causes it to turn grey and is no longer used in modern laundries

7. Starch

  • This is a stiffening agent used to impart a better appearance to the fabric.

  • The use of starch has declined due to the minimum-iron finishes on fabrics and garments and the reduced use of cotton in favour of man-made fibres.

  • However, there are some articles that have a better feel and drape when starched and it is particularly essential for napkin folds.

  • Since polyesters do not have the ability to absorb starch they are stiffened with sizing agents.

Types of starch

  • Hot-Water Starches

  • Cold-Water Starches

  • Gelatin

  • Glue

  • Synthetic Sizing

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