Solvents in Cleaners

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Solvents in Cleaners

• Albert F. Joseph
• The Dow Chemical Company

Source of photos and data for graphs is
Dow unless otherwise noted
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Agenda

• Role of a solvent in cleaning formulations
• Household Cleaners (Hard Surface, Glass, Floor)
• How do you choose and evaluate a solvent
• Tools for solvent selection
• Regulatory comments

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Abbreviations

• IPA - Isopropyl alcohol
• ETOH - Ethanol
• PG - Propylene glycol
• MEK - Methyl ethyl ketone
• 1,1,1-Tri - 1,1,1-trichloroethylene
• PM - Propylene glycol methyl ether
• DPM - Dipropylene glycol methyl ether
• TPM - Tripropylene glycol methyl ether
• PnB - Propylene glycol butyl ether
• DPnB - Dirpropylene glycol butyl ether

• PnP - Propylene glycol propyl ether
• DPnP - Dipropylene glycol propyl ether
• EB - Ethylene glycol butyl ether
• DB - Diethylene glycol butyl ether
• EHEX - Ethylene glycol hexyl ether
• EPh - Ethylene glycol phenyl ether
• PPh - Propylene glycol phenyl ether

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Solvents in Cleaners
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Role of Solvents in Cleaners

• Solvency Power (solubilize soils, fragrance)
• Coupling Ability (couple soils)
• Reduce Surface Tension (wetting)
• Evaporation Rate
• Penetrate grease
• Lower soil viscosity
• Modify soil substrate (open pores, alter surface)
• Formulation stability

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Role of Solvent in Cleaning
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Removing Elbow Grease
Mechanical Energy
ME with Interfacial Tension Reduction
ME with Viscosity Reduction
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Solvent Properties Important to Formulators

• Efficacy
• Flash point (flammability)
• Evaporation rate
• Water solubility
• Odor
• Biodegradability
• Cost

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Household Cleaners

• Applications
• Hard surface
• Glass
• Floor
• Solvents Used
• Glycol Ethers
• Alcohols
• Amines
• Other (terpenes, pine oil, hydrocarbons)

Household cleaners account for about 5 of total
industry demand for solvents
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Percent Formulations by Solvent Type1
1 - Advanced Cleaning product formulations, E.W.
Flick
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Role of Solvent in Household Cleaning

• Solvency
• Coupling ability
• Surface tension reduction
• Evaporation control
• Clarity (homogeneity)
• Soil viscosity reduction

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Glycol Ethers
CH3-CH2-CH2-CH2-O-CH2-CH-OH CH3
Hydrophobe
Hydrophile

• Interfacially active
• Varying water solubility
• Solvency
• Coupling ability

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Aqueous Surface Tension of Glycol Ethers
HLB
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Surface Tension Reduction(Floor Tile)
0 Glycol Ether (Retracts after mechanical
spreading)
4 Propylene glycol propyl ether (Maintains shape
upon mechanical spreading)
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Other Solvents in Household

• Amines
• Soil surface modification
• pH modification
• Alcohols
• Evaporation control (glass cleaners)
• Preservation
• Clarity

• Natural solvents
• d-limonene
• Pine oils
• Hydrocarbons
• Solvency

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General Formulation Questions

• What is your application?
• What is the role of the solvent? (reduce surface
  tension, solubilize other components, coupling or
  solubilizing of soil, etc.)
• Does the solvent need to have water solubility?
• What evaporation rate are you looking for?
• Do you have safety, environmental or regulatory
  concerns?

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How I clean will affect solvent choice...

• Spray fast evaporation
• Bucket-dilutable/concentrate 100 water
  soluble
• Heavy greases hydrophobic

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How do I determine cleaning performance
Performance Evaluation for aTypical All-Purpose
Cleaner

• Scrubbing test
• Substrates floor tile, ceramic tile, metal,
  painted wall board
• Soil hydrophobic, particulates, sebum, soap
  scum
• Cleaner application sponge, brush, number of
  strokes, soak/no soak
• Results evaluation reflectance, visual grading,
  strokes to clean, streaking/filming
• Compare to a standard

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Cleaning Performance Comparison
Formulation without solvent and surfactants
Formulation surfactants
Formulation surfactants EB
Formulation surfactants DPnB
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Cleaning Performance Comparison
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Effect of Non-Ionic Surfactant Type (1) and
Solvent Type (4) on Cleaning Performance for a
APC Cleaner
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Tools for Solvent Selection

• HLB values
• Water solubility vs. temperature
• Hansen solubility parameter modeling
• Coupling ability
• Physical properties
• Evaporation rate
• Viscosity
• Surface tension

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Relative Solubility Hydrophile/Lipophile Balance
(HLB)
Hydrocarbons lt Glycol Ethers lt
Lower Alcohols
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General Glycol Ether Characteristics
Note Trends for E-series are the same except
for water solubility
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Water Solubility vs. Temperature
HLB
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Coupling Performance
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Lower AlcoholsProperties
All three alcohols are completely soluble in
water at room temperature. Methanol is the most
hydrophilic.
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Lower AlcoholsApplications
Source http//householdproducts.nlm.nih.gov/ingr
edients.htm
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Solubility ParametersHansen Theory

• Three parameters Dispersive (D), Polar (P),
  and Hydrogen Bonding (H)
• Solubility occurs when solvent solubility
  parameters match those of soil
• Three dimensional plots used to show differences
  between the soils and solvents
• Can become complicated when dealing with multiple
  solvents and/or multiple soils
• Computer modeling tools are available

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Solubility ParametersSimple Example
Which solvent should be selected for each soil?
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A Brief Legislative Overview

• The Clean Air Act Amendments of 1990
• - Title I Volatile Organic Compounds(VOC)
• - Title III Hazardous Air Pollutants(HAPs)
• CAAA lists 189 materials or classes of materials
  as HAPs. Many solvents used in HI cleaners,
  including ethylene glycol-based glycol ethers and
  methanol appear on the HAPs list.
• Always check the latest list. For example,
  ethylene glycol butyl ether has recently been
  de-listed.
• Title 17 of The California Code of Regulations
• - California Air Resources Board VOC Limits for
  Some Consumer Cleaning Products

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California Legislation for Consumer Products

• Proposes VOC limits for 24 classes of consumer
  products
• - Bathroom and floor cleaners (7 VOC)
• - Oven degreasers (8 VOC)
• - Cooking sprays (18 VOC)
• - Deodorants (10 VOC)
• - Furniture polish (25 VOC)
• - Glass Cleaners (8 VOC)
• - Shaving cream (5 VOC)
• - General Purpose Cleaners (10 VOC)
• Solvents with a vapor pressure lt 0.1 mmHg _at_20
  deg.C
• are not considered VOC
• Exemptions
• - Negligibly reactive compounds, such as
  acetone
• - Certain fragrances
• Note This list was prepared August, 2005. It
  can and does get modified. For example, the
  number of classes is changing to 131.

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Photochemical Reactivity

• VOC molecules react at different rates to create
  ground level ozone
• Not all solvents contribute equally to ozone
  formation
• Alkenes gt Aromatics gt Aliphatics / Oxygenated
• Mass-based limits provide no differentiation with
  regard to the properties of different types of
  solvents
• The same mass-based VOC content could mean very
  different ozone creation potential depending on
  which solvent is used
• Majority of hydrocarbon and oxygenated solvents
  are treated the same - not a science based
  approach
• Photochemical reactivity offers a viable science
  based approach
• Leads to a higher reduction in ozone creation
  potential
• Increases formulation flexibility
• Maintains/improves coating performance

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EPA Sets Direction for Future VOC Control

• EPA has updated its VOC policies through
  publication of an interim policy statement
  reactivity is the key element
• The new reactivity-based guidance from EPA allows
  regulators to achieve ozone reduction objectives
  more efficiently than by traditional mass-based
  limits

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Additional VOC Comments

• Canada currently only has guidelines
• Guidelines are essentially equivalent to the US
  EPA National Rule
• Surveys of consumer products are being conducted
• Preparing for mandatory rules

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Solvents in CleanersSummary

• Play important roles in cleaners
• Available with a variety of chemistries,
  properties, and features
• Selection depends on the application and the role
  it is expected to play
• Compliment other formulation components
• Always consider potential safety and
  environmental concerns

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Abbreviations

• IPA - Isopropyl alcohol
• ETOH - Ethanol
• PG - Propylene glycol
• MEK - Methyl ethyl ketone
• 1,1,1-Tri - 1,1,1-trichloroethylene
• PM - Propylene glycol methyl ether
• DPM - Dipropylene glycol methyl ether
• TPM - Tripropylene glycol methyl ether
• PnB - Propylene glycol butyl ether
• DPnB - Dirpropylene glycol butyl ether

• PnP - Propylene glycol propyl ether
• DPnP - Dipropylene glycol propyl ether
• EB - Ethylene glycol butyl ether
• DB - Diethylene glycol butyl ether
• EHEX - Ethylene glycol hexyl ether
• EPh - Ethylene glycol phenyl ether
• PPh - Propylene glycol phenyl ether