Transcript Colloid and Surface Phenomena of Liquid Laundry Detergent

Colloidal and Surface Phenomena
of Liquid Laundry Detergent
Dan Boek
Erika Indivino
Katie Marso
Karey Smollar
April 18th, 2002
History
Clothes first cleaned by mechanical means
Production of soaps
First 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 detergent
Included surfactants and builders
Combinations became more complex
Sodium triphosphate (STP)
Very effective builder
Use restricted in 1960’s because it caused
eutrification in rivers
New additives are continually being introduced
History
Liquid laundry detergent
1970’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 water
Builders prevent calcium and magnesium deposits
Good dispersion properties
Liquid detergents spread easily
Soil antiredeposition capability
Surfactants keep soils in suspension
Design Considerations
High solubility in water
Liquid detergents dissolve faster than powders
Foaming
Psychological affect, foam means detergent is
working
Odor
Perfumes and fragrances
Color
Design Considerations
Toxicity
Exposure through skin, ingestion, inhalation
Environmental affect
Use of phosphates
Convenience
Easier to pour, direct application on stains
Cost
Types of Fabrics
Fabrics require specialized soil removal
Textile versus synthetic fabrics
Different calcium content
Wettability due to hydrophobic and hydrophilic
nature
Complexing agents react differently with each
type of soil
Types of Fabrics
Sodiumtriphosphate
Effectiveness 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
Tablets
Directed to elderly and students
New and expensive
Hold 25% of market in some European countries
Pouches
Introduced in April 2001
Liquid detergent in polyvinyl alcohol skin
Dissolves in seconds, leave behind no residue
Main Components
Anionic Surfactants
Nonionic Surfactants
Soaps
Builders
Solubilizers
Alcohols
Enzymes
Optical Brighteners
Stabilizers
Fragrances
Water
Anionic Surfactants
Tetrapropylenbenzene (TPS)
-used in earlier stage production of detergents to first replace
soap
-branching increases the wetting ability but limits effective
detergency
Linear Alkylsulfonate (LAS)
Sodium linear alkylsulfonate (LAS)
-demonstates good detergency ability and is not very
sensitive to water hardness
Secondary Alkanesulfonates (SAS)
Secondary Alkanesulfonates (SAS).
-highly soluable surfactant demonstrating fast wetting
properties and chemical stability of alkali and acids
Olefinsulfonates (AOS)
R1–CH2–CH=CH–(CH2)n–SO3Na
Alkenesulfonates
Hydroxyalkanesulfonates
- produced using alkaline hydrolysis process
- shows less sensitivity to water only under certain
conditions such as chain length and type of chemical
bonding
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 Builders
Trisodium phosphate is the most common type of builder
Figure 3: Trisodium Citrate (NaCit)
Zeolites : Molecular formula: Na2OAl2O3*4.5H2O.
-water insoluble builder
-10 micrometer diameter
-reduces soil redeposition by replacing calcium and
magnesium ions with sodium
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
Stabilizers
Prevent 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 Additives
Optical Brighteners
-Used to brighten fabric appearance by converting ultra
violet light into longer wavelengths of visible blue light
Fragrances
Alcohols
Water
Contact Angle
 FW   FS
cos 
 SW
soil-water interface
fabric-water
interface
Water
Fabric

Soil
fabric-soil interface
Young Equation
 FW   FS
cos 
 SW
After surfactants are added: γFW = γSW = 0
Interfacial tension between soil and fabric
remains constant, so γFS > γFW
Θ>90 degrees
Contact 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 degrees
The 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-layer
Continuous lamellar crystalline structure
Multilamellar Vesicles
Bilayers form multalamellar vesicles to
minimize hydrocarbon chain and solvent
interactions
Unilamellar 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 polymer
Hydrophylic 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 Repulsion
Poor 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 antiredeposition
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
Liquid detergents are produced either in a
batch reactor or a continuous blending
process.
Surfactants
STPP/Zeolite
Sodium Sulphate
Sodium Perborate
Sodium Carbonate
Sodium Silicate
Minors
Mixing and
Homogenizing
Liquid
Detergent
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 bottles
Refill bottles 65-90% smaller than original container
Environmental Concerns
Adjust to environmentally-friendly washing
machines
Reduced:
• 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
3
2.8
2.6
$ Billion
2.4
Powder Detergent
Liquid Detergent
2.2
2
1.8
1.6
1.4
1997
1998
Year
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 Breakdown
Market Breakdown of Laundry Detergents
All (Unilever)
7%
Gain (Procter &
Gamble)
7%
Purex (Dial)
7%
Other
22%
Wisk (Unilever)
7%
Cheer (Procter &
Gamble)
6%
Arm & Hammer
(Church &
Dwight)
5%
Tide (Procet &
Gamble)
39%