5- WASHING CHEMICALS

Chapter 5 summaryEnter

Substances defined as detergents are those that have the property of removing dirt from an object without damaging it.

Detergents are combinations of chemical compounds which, associated with the factors of time, temperature and mechanical action, allow a surface to be freed of its dirt.

DEFINITION:

Alkali

Neutral

Manuals, etc.

DETERGENTS

CHEMICALS WASHING

Chlorine

Activeoxygen

Optical

WHITENERS

Neutralisers

Disinfectants

SOFTENERS

Neutralisers

Starch

Fire retardants

FINISHING PRODUCTS

DETERGENTS

SURFACTANTS

Anionic surfactants

Non-ionic surfactants

Cationic surfactants

Amphoteric surfactants

BUILDERS

Sodium tripolyphosphate

Zeolites

Sodium carbonate

Polycarboxylates

WHITENING SYSTEM

Chemical whiteners

Whitening activators

Optical whitener

ADDITIVES

Enzymes

Anti-redepositing agents

Corrosion inhibitors

De-foaming angents

Perfume

AUXILIARY AGENTS

Water

Sodium sulphate

Typical composition:

These are the constituents of detergents, and provide special wetting, foaming and detergent properties.They reduce the surface tension, causing water to behave in a particular fashion in the presence of solids and fats.

Hydrophilic end:

Lipophilic end

Diagram of a surfactant molecule:

SURFACTANTS

Types of surfactants:

Depending on their Ionic behaviour in aqueous solution, they are classified into 4 groups:

Anionic S. (-)

Noionic S. (nil)

Cationic S. (+)

Anphoteric S. (depending on mean pH)

Manual dishwasher

Linen detergent for machines

Softener for linen

Creams, disinfectants, etc.

Examples of use:SURFACTANTS

How do surfactants work?

The soiled fabric comes into contact with the water

SURFACTANTS

The bath with detergent wets the fabrics and the dirt

The surfactants separate the dirt from the substrate

The dirt is stabilised. The hydrophilic part in contact with the bath. The lipophilic part in contact with the dirt.

They are added to detergents to protect or improve the detersive efficiency. They add detergent properties that improve the detergent process.

They remove the hardness from the water Zeolites

They provide the bath with alkalinity Sodium carbonate

They prevent the dirt from re-depositing Policarboxilates

They improve the emulsion and dispersion of the dirt

Sodium tripolyphosphate….

BUILDERS

In laundering we use the term "whiteners" to refer to the chemicals that remove the colouring dirt and keep the fabrics white. In the composition of a detergent, we can find the following:

Whitening activator:

This enhance the whitener so that it acts at low temperature

Chemical whiteners:

For example: Perborate and percarbonate DO NOT attack the colours

Optical whiteners:

These reflect the light and give the sensation of greater whiteness

WHITENING SYSTEM

Minority substances in the composition of a detergent. Their properties differ from one detergent to another:

ADDITIVES

ENZYMES: These are natural proteins that enhance detergents and allow them to work at a low temperature. Each type of enzyme degrades one type of substance.

ANTI-REDEPOSITING AGENTS: These keep the dirt removed from the fabrics in suspension in the bath.

CORROSION INHIBITORS: These are used to protect the substrates on which the detergent acts.

DE-FOAMING AGENTS: These are needed to ensure that the detergent solution possesses an optimum level of foam.

PERFUME: This is added to make the product pleasant to use and to leave a residual aroma.

AUXILIARYAGENTS

Without a mission in the detergent process, they are necessary to ensure that detergents have a presence that aids their use and that allows their properties to be preserved.

Water Auxiliary presentation agent in liquid detergents. Influences fluidity, viscosity, density, etc.

Sodium sulphate

A colourless and crystalline powder. It acts as an absorbent and helps to disperse all the compounds of a detergent powder evenly.

An oxidising agent is a chemical element that captures electrons, ending up with a positive charge.

A reducing agent is a chemical element that cedes electrons, ending up with a less positive charge than it had.

TYPES

OXIDANTS

Hydrogen peroxide

Sodium perborate

Sodium percarbonate

Peracetic acid

Sodium hypochlorite

Chloroisocyanurates

Ozone

REDUCERS

Sodium hydrosulphites

Sodium bisulphites

Oxidising agents:These release active oxygen, which is ultimately responsible for bleaching out and removing coloured stains. In addition they possess disinfecting properties.

Whitening process:Effectiveness of whiteners vs temperature

Each type of oxidising agent has a temperature of maximum effectiveness

80-85ºC60ºC55-60ºC20-25ºC

Reducing agents:

These are used in special processes. They are especially effective on synthetic colourants, and are widely used to remove colour bleeding on white articles.

Their characteristic odour is due to their compounds with sulphur.

Softeners

Washing processes end up reducing the softness and flexibility of fabrics. On washing the fibres become tangled, and on drying they do not return to their natural position, which reduces their resistance.

SOFTENERS

Their main component (cationic surfactant) provides lubrication to help the fibres return to their natural position

In addition, softeners contain:PerfumePreservativesAdditives: colourants, optical whitening agents, disinfectants, etc.Presentation aids

Improves water extraction during spinning

Makes ironing easier

Gives garments a fluffy feel

Neutralises residual alkalinity

Reduces or eliminates static electricity

Perfumes the linen

Properties:

Added to the end of the detergent process, this group of products restores the treated fabrics to their initial conditions.

They help to neutralise, lighten, soften and condition the linen before it is dried and ironed.

Finishing products:

END OF CHAPTER 5 SUMMARY