Automatic stability analyses for pigment based inkjet inks

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Automatic stability analyses for pigment based
inkjet inks
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Inkjet inks applications
Pigment based ink advantages

• Better UV durability / light fastness
• Good compatibility with packaging
• Environmentally friendly
• Safer

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Inkjet inks applications
Pigment based ink drawbacks

• Sedimentation of pigments
• Colour gradient
• Aggregation of pigments
• Jet blocking
• Packing of the sediment
• Inconsistency of colours through life of
  cartridge

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Inkjet inks applications
Need for an accurate and objective technique to
measure stability of inkjet inks
Turbiscan technology
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Multiple Light Scattering

BSk(1/l)
lk(d/f)
Backscattering
Transport length of the photon
With k (dh) dh detector height
With d particle mean diameter f volume
fraction
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Multiple Light Scattering - Effect of the volume
fraction-
DILUTED REGIME
CONCENTRATED REGIME
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Multiple Light Scattering - Effect of the
particle size -
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Principle of measurement
Acquisition of the - Transmitted flux
(T) and - Backscattered flux (BS)
Analysis of diluted to concentrated products
1 Acquisition every 40 µm
High vertical resolution
One scan lasts 20 seconds
Measurement of fast destabilisations
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Principle of measurement
One scan
Multi scans
Acquisition time of each profile
Backscattering ()
Height (mm)
Height (mm)
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Principle of measurement
Particle size variation
Particle migration
Coalescence or flocculation
Sedimentation or creaming
t0 min
t0 min
t15 min
t15 min
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Inkjet inks applications
Migration of pigments

• Problem pigments tend to settle because of
  density difference
• Solutions
• Increase viscosity (limited to 3mPa.s for jet)
• Decrease particle size (induce colour changes)
• Find the best compromise and test the best
  formulation

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Inkjet inks applications
Migration of yellow pigments
Sediment thickness kinetics
Sediment
Phase thickness (mm)
Clarification
Time (h)
Migration velocity 0.2 mm/h
2 peaks 2 populations of particles
? Measurement done in less than 1 day
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Inkjet inks applications
Aggregation of pigments

• Problem pigments tend to stock together because
  of electrostatic attraction
• Solution use polymers to coat the pigments
• Need test the efficiency of the additives

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Inkjet inks applications
Aggregation of pigments
Particle size increase
Sediment
Clarification
Backscattering ()
Particle size increase
Time (h)
? Measurement done in less than 15 days
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Inkjet inks applications
Packing of the sediment

• Problem aggregation of the pigments in the
  sediment, no redispersion possible
• Need Measure the product in real conditions (no
  dilution)

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Inkjet inks applications
Packing of the sediment
Aggregation of sediment
Sediment
Clarification
Particle size increase in the sediment packing
? Measurement done in 12 hours
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Inkjet inks applications
Automated analyses

• Automatic handling with robot (80 runs per hour)
• Automatic data processing on whole group of
  samples
• Automatic sorting of samples with warning level
• Automatic reporting

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Conclusion
The Turbiscan technology is

• Easy to use
• Reliable
• Time saving
• Objective

• So you have more time and information to focus
  on formulation