Colloidal and Surface Phenomena of Liquid Laundry Detergent

Dan BoekErika IndivinoKatie Marso

Karey Smollar

April 18th, 2002

                                                                                                         

              

              

  

 

 

History

Clothes first cleaned by mechanical means

Production of soapsFirst produced in the 15th century

Combine fats and sodium hydroxide

Renewable, biodegradable resources

Negative affects of hard water

History

Synthetic detergents

First produced in 1916 in Germany• Introduction of margarine

• Large bodies of water covered in foam

Production took off in the U.S. after WWII• Mainly used for dishwashing and fine fabrics

History

1946, first all-purpose laundry detergentIncluded surfactants and buildersCombinations became more complex

Sodium triphosphate (STP)Very effective builderUse restricted in 1960’s because it caused eutrification in rivers

New additives are continually being introduced

History

Liquid laundry detergent1970’s, became popular in the U.S.

More convenient for consumers• Easier to handle

• Do not contain bleaching agents

• Remove stains better at lower temperatures

Sales have soared above powders in last decade

Have reached 50/50 market split in the U.S.

Design Considerations

Excellent soil removal

Low sensitivity to hard waterBuilders prevent calcium and magnesium deposits

Good dispersion propertiesLiquid detergents spread easily

Soil antiredeposition capabilitySurfactants keep soils in suspension

Design Considerations

High solubility in waterLiquid detergents dissolve faster than powders

FoamingPsychological affect, foam means detergent is working

OdorPerfumes and fragrances

Color

Design Considerations

ToxicityExposure through skin, ingestion, inhalation

Environmental affectUse of phosphates

ConvenienceEasier to pour, direct application on stains

Cost

Types of Fabrics

Fabrics require specialized soil removal

Textile versus synthetic fabricsDifferent calcium content

Wettability due to hydrophobic and hydrophilic nature

Complexing agents react differently with each type of soil

Types of Fabrics

SodiumtriphosphateEffectiveness dependent on hydrophilic/hydrophobic nature of the fiber

Efficient removal of soils from synthetic or cotton garments, which are hydrophilic

Minimal affect on hydrophobic textile fibers

Different fabric and soil types are dealt with by using a mixture of compounds in detergents

History

TabletsDirected to elderly and studentsNew and expensiveHold 25% of market in some European countries

PouchesIntroduced in April 2001Liquid detergent in polyvinyl alcohol skinDissolves in seconds, leave behind no residue

Main Components

Anionic Surfactants

Nonionic Surfactants

Soaps

Builders

Solubilizers

Alcohols

Enzymes

Optical Brighteners

Stabilizers

Fragrances

Water

Anionic SurfactantsTetrapropylenbenzene (TPS)

-used in earlier stage production of detergents to first replace soap-branching increases the wetting ability but limits effective detergency

Linear Alkylsulfonate (LAS)

-demonstates good detergency ability and is not very sensitive to water hardness

Sodium linear alkylsulfonate (LAS)  

Secondary Alkanesulfonates (SAS)

-highly soluable surfactant demonstrating fast wetting properties and chemical stability of alkali and acids

Secondary Alkanesulfonates (SAS).  

- produced using alkaline hydrolysis process- shows less sensitivity to water only under certain

conditions such as chain length and type of chemical bonding

Olefinsulfonates (AOS)

    

R1–CH2–CH=CH–(CH2)n–SO3Na     Alkenesulfonates       

Hydroxyalkanesulfonates       

   

     

 

Nonioinic Surfactants

An essential ingredient found in smaller quantities which are used for stabilizing the micelle formations and prevent redeposition

Advantages of Builders

Enhances effects of surfactants

Used to reduce water hardness, Mg2+ and Ca2+

Enables the production of cheaper detergent while retaining the cleaning properties

Types of BuildersTrisodium phosphate is the most common type of builder

Zeolites : Molecular formula: Na2OAl2O3*4.5H2O. -water insoluble builder -10 micrometer diameter -reduces soil redeposition by replacing calcium and magnesium ions with sodium

Figure 3: Trisodium Citrate (NaCit)

Enzymes

Help with the removal dried in stain from milk, cocoa, blood, egg yolks and grass

Enzymes commonly used are proteolytic, amylolytic and lipolytic

Enzymes cause hydrolysis of peptide, glucosidic, or ester linkages

StabilizersPrevent redeposition of negatively charged particles back on the neutral fabric surfaces

Sodium carbomethyl cellulose (SCMC)

Molecular weight is between 20,000 and 500,000

-Attaches itself to the fibers adding to the negative

Other AdditivesOptical Brighteners

-Used to brighten fabric appearance by converting ultra violet light into longer wavelengths of visible blue light

Fragrances

Alcohols

Water

Contact Angle

Water

Soil

Fabric

soil-water interface

fabric-waterinterface

fabric-soil interface

SW

FSFW

cos

Young Equation

SW

FSFW

cos

After surfactants are added: γFW = γSW = 0Interfacial tension between soil and fabric remains constant, so γFS > γFW

Θ>90 degreesContact area between soil and fabric = 0

Roll-Up

As Θ>90 degrees, the roll-up mechanism takes place

Without Surfacant

Without surfactant, surface tensions remain constant, Θ < 90 degreesThe soil is partially removed by mechanical agitation

Packing Parameter

Packing parameter:

p=v/aolc • ao=surface area of headgroups

• V = volume of hydrocarbon chains

• lo = maximum length of chains

Packing Geometry

Multilamellar Structure

Headgroup area diminishes in the presence of salt ions, NaCit

½ > p > 1 so structure is bi-layerContinuous lamellar crystalline structure

Multilamellar Vesicles

Bilayers form multalamellar vesicles to minimize hydrocarbon chain and solvent interactionsUnilamellar vesicle

Multilamellar Vesicles

Flocculation

Water is a poor solvent with salt ions present

Chain length decreases due to poor solvency

Van der Waals forces

Flocculation and phase separation result

Decoupling Polymer

Decoupling polymerHydrophylic backbone and hydrophobic side chains

Side chains dissolve in oil

Backbone dissolves in water

Steric repulsion causes the lamellar droplets to repel, hindering flocculation

Steric RepulsionPoor solvent without decoupling polymers

Poor solvent with decoupling polymers

Particulate Soil

METHODS OF REMOVAL

Mechanical Energy is the primary type of removal and used to enhance anti-redeposition

Potential Energy barriers is greatest near the surface, DLVO Theory

Using Anioinc surfactant to create electrical Charge on the surfactant and fiber causing repulsion

Diagram, PE vs. distance

Potential Energy vs. pH Diagram

Potential of various fibers as a function of pH a) Wool; b) Nylon; c) Silk; d) Cotton; e) Viscose

Calcium Containing Soil

Found on textile fabric surfaces

Effective detergency is dependent on type of washing solvent used

Increases water hardness which decreases the solubility

Slight solubility can cause calcium deposit break-up

Types of Fabrics

Cotton, Synthetic, textile

Different hydrophobic/hydrophilic nature

Effective detergency is dependent of “wettability” of the cloth and the type of complexing agent used

Cleaning mixed soils on blending fabrics cause complementing effects

Manufacturing

Surfactants

STPP/Zeolite

Sodium Sulphate

Sodium Perborate

Sodium Carbonate

Sodium Silicate

Minors

Mixing and Homogenizing

Liquid Detergent

Liquid detergents are produced either in a batch reactor or a continuous blending process.

Packaging

3 Main Purposes:Maintain quality of detergent

Supply detergent information

Make handling easy

Packaging

Company Considerations:Compatibility

Cost

Safety

Waste

Convenience

Packaging

Typical bottles are recyclable plastic

Gradually, companies are adding a percentage of recycled plastic to their bottles.

Generally 25% recycled material

Concentrated detergents

Refillable bottlesRefill bottles 65-90% smaller than original container

Environmental Concerns

Adjust to environmentally-friendly washing machinesReduced:

• Water

• Energy

• Temperature

Water consumption• Minimize amount required for detergent to function

• Adapt formula to wash in poor conditions

Liquid Detergent Sales Continue to Grow:

Liquid Detergent Sales

1.4

1.6

1.8

2

2.2

2.4

2.6

2.8

3

1997 1998

Year

$ B

illio

n

Powder Detergent

Liquid Detergent

Market Sales

Liquid detergent sales top powders in 1998$3 billion sold in liquid

$1.8 billion sold in powder• Liquids more popular due to convenience and better

performance

Market BreakdownMarket Breakdown of Laundry Detergents

Other22%

Tide (Procet & Gamble)

39%Arm & Hammer (Church &

Dwight)5%

Cheer (Procter & Gamble)

6%

Wisk (Unilever)7%

Purex (Dial)7%

All (Unilever)7%

Gain (Procter & Gamble)

7%