Surface Modification of Carbon Black
Next Generation Inkjet
Pigments
Paul Palumbo
Boston Chapter IS&T, May 2001
2
Outline
• Generation 1 Pigments
– Simple diazonium treatment
– Dispersion and Ink properties
• Generation 2 Pigments
–
–
–
–
Conceptual design
Secondary attachment
Polymer attachment
Properties
• Laser Quality
3
Some Basic Functional Groups
OH
CO2 -
CO2 -
CO2 -
CO2 SO3 -
B(OH)2
NR3 +
N
+
-
CF3
O2C
NH
O
PO3=
CO2-
4
Generation 1 Inkjet Pigments
✔Light Stability
✔Dispersion Stability- Charge and Particle
Size
✔Print Head Reliability- Purity
✔High Optical Density
✔Improved Intercolorbleed
✔Improved Waterfastness
5
Generation 1 Inkjet Pigments
✘Highlighter Smear
✘Wet Rub
✘Dry Rub
✘Dry Time
Optimizing these performance properties generally
requires formulation with surfactants and polymeric
additives
6
Generation 2 Inkjet Pigments
Eliminate the need for ink additives...
Achieve all performance goals
through
surface groups.
7
Network-Forming Groups Attached to Surface
8
Secondary Surface Chemistry
Diazonium
Reaction
Pigment
Reactive
Intermediate
9
Carbon Black
10
Secondary Surface Chemistry
• First group provides a “hook”
• Second group introduces the desired properties
• Now it’s possible to attach groups that are not
compatible with diazonium chemistry
• Many variants
–
–
–
–
–
Condensation reactions
Coupling reactions
Addition-elimination reactions
Displacement reactions
Etc...
11
Reactive Surface Groups
COCl
CON3
SO2Cl
O
COOEt
O
O
12
Reactive Functional Groups: Vinyl Sulphone
O
O
S
pH > 12
O
O
S
OSO3-
R-XH
O
O
S
X-R
X = O, S, NH
13
Attachment via Vinyl Sulfone Surface
• Polyethylene imines
• Amino alcohols
• Dendrimers
– Starburst
– Astramols
• Polyols
– Polyvinyl alcohol
– Sorbitol
– Sugars and Polysacharides
• Gelatin
• PEG, PPG
• Other polymers
14
Polyethylenimine
NH2
O
O
S
PEI
H2N
H2N
H2N
OSO3-
•
•
•
•
Highly cationic
Waterfast in 5-10 minutes
Improved smear
Binds well to many surfaces
H2N
NH2
NH2
NH2
NH2
NH2
15
Reactive Functional Groups: Amine
NH2
H2N
H2N
H2N
H2N
NH2
NH2
NH2
NH2
NH2
Reaction with: •
•
•
•
•
•
•
•
•
Anhydrides
Acid chlorides
Lactones
Active esters
Alkyl halides
Vinyl sulphones
Polystyrene co-acrylic acid
Polyacrylic acid
Etc.
16
Succinic Anhydride
-
NH2
H2N
H2N
H2N
H2N
NH2
NH2
NH2
NH2
NH2
O O O
O2C
O
HN
H2N
H2N
HN
O
CO2NH2
NH
NH2
NH2
NH
NH2 O
CO2-
Amphoteric
• Adjust isoelectric point
• Formulation flexibility
• Optimize for specific media
O
CO2-
17
Polystyrene co-Acrylic Acid
NH2
H2N
H2N
NH2
NH2
NH2
H2N
H2N
NH2
PSAA
dehydrate
NH2
•
•
•
•
•
Covalent polymer attachment
Excellent smear resistance
Waterfast in 1 minute
Very rub resistant
Media independence
18
Reactive Functional Groups: Vinyl
Monomer
Initiator
• Grow polymers from surface
• Vary monomer mix
19
Laser Quality Goals
• Print speed = dry time
• Print quality
– OD, edge acuity, intercolorbleed, etc.
• Print durability
– Waterfast, smearfast, rub resistant, etc.
• Printhead reliability
Generation 2 pigments are enabling!
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Thank You!