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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%
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