Developments in the Deinkability of HP Inkjet Inks€¦ · HP Inkjet Inks. Objectives •Discuss ... Method 11 chemistry (b.fl. pH ca. 10) Method 11 chemistry + lo shear (b.fl. pH

© 2010 Hewlett-Packard Development Company, L.P.The information contained herein is subject to change without notice

Gregg Lane, Minedys Macías and Nils Miller

Hewlett-Packard Co., San Diego

With results from Elisabeth Hanecker - PTS, Munich

Developments in the Deinkability of HP Inkjet Inks

Objectives

•Discuss parameters that positively affect inkjet deinkability.

•Discuss how the hydrophobicity and particle size of inkjet inks can be enhanced for improved floatation deinking.

•Share new results on the deinkability of HP pigmented inks − As a function of paper composition

− As a function of ink design

2

CTP/PTS Deinking symposium, Munich 2010

Pulping shear

Flotation pH

Printing paper design

Collector

Ink design

Coagulating agents

3


EnhancingInkjet

Deinkability

Effect of pH on a typical HP pigmented ink

0

20

40

60

80

100

120

4 5 6 7 8 9 10 11 12 13 14

% D

ispers

ed P

igm

ent

pH

4


Pigment crashes out of suspension at reduced pH, becomes hydrophobic

• Ink samples prepared at varying pH, centrifuged

• Light absorbance measured on supernatant and compared to ‘stable’ control at alkaline pH

Hydrophobic Hydrophilic

30

5860

6366

71

48 48

39

0

10

20

30

40

50

60

70

80

Method 11 chemistry (b.fl. pH ca. 10)

Method 11 chemistry + lo shear (b.fl. pH ca 10)

Modified chemistry + lo shear (b.fl. pH=8.3)

Me

asu

red

val

ue

(%

)

Ink elimination Luminosity DP Filtrate darkening

Deinkability resultsFlotation process variations, wood-free paper

Variations in shear and pH

Sample: INGEDE test file on Xerox office paper5


Effect of coagulants on a typical HP pigmented ink generation of agglomerates

6


Sample #1

Sample #2

Coagulated Ink

Effect of coagulantson a typical HP pigmented ink, continued

7


Sample #1

Sample #2

1 μm

2 μm

4 μm

1 μm

Estimated particle size distribution

Coagulant destabilization Effects on deinkability, wood-free paper

8


30

6363

71

48

18

0

10

20

30

40

50

60

70

80

Print without coagulant Print containing coagulant

Me

asu

red

val

ue

(%

)HP pigmented black ink


The particle size of the pigment agglomerates will be larger in the presence of coagulants in the paper – which correlates to improved deinkability

Effect of pH on deinkability of HP black pigment IJ ink on TMP media

0

10

20

30

40

50

60

70

80

90

100

10 7.3 5.4

Me

asu

red

val

ue

( 4

ke

y va

ria

ble

s)

pH after pulping

Filtrate darkening Brightness R457 (DP) Ink elimination Yield

usable range

usable range

usable range

9


Excellent Filtrate Darkening!

New results: Deinkability of HP black pigmented ink printed on paper containing mechanical pulpConditions: modified method 11 chemistry and low shear

Average pH before flotation = 8.5 10


Ink Elimination correlates to Aluminum concentration!

0

10

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30

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50

60

70

80

0

5000

10000

15000

20000

25000

Paper 1 Paper 2 Paper 3 Paper 4

Ink e

limina

tion (%

)

μg

of ele

ment /

g o

f p

aper

sam

ple

(p

pm

)

Al+3 Ink elimination

usable range

New results: Deinkability of HP black pigmented ink printed on paper containing mechanical pulpConditions: modified method 11 chemistry and low shear

Average pH before flotation = 8.5 11


Filtrate darkening correlates to Aluminum concentration!

0

5

10

15

20

25

0

5000

10000

15000

20000

25000

Paper 1 Paper 2 Paper 3 Paper 4

Filtrate

da

rkening

(%)

μg

of ele

ment /

g o

f p

aper

sam

ple

(p

pm

)

Al+3 ΔY

usable range

New results: Ink VariationCurrent vs. prototype HP pigmented inkConditions: low shear + method 11 chemistry

Sample: INGEDE test file on paper containing mechanical pulp12


Prototype ink shows improved deinking

47

68

59

69

3 2

0

10

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70

80

Commercially available ink Prototype ink

Me

asu

red

val

ue


usable range

usable range

usable range

Conclusions

• Flotation of inkjet inks is enhanced when:

…Pigment hydrophobicity increases

…Pigment particle size increases

Solutions could include coagulating agents and choice of pH in the deinking process

…There is an increased Al+3 content in the paper− More work is needed to understand the mechanism and the potential impact

on other mill variables.

− This may explain previous positive deinking results obtained on the HP web press

•New prototype inks show improved deinking.

•Continue to engage with paper companies to better understand ink and media interactions.

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Documents

Developments in the Deinkability of HP Inkjet Inks€¦ · HP Inkjet Inks. Objectives •Discuss ... Method 11 chemistry (b.fl. pH ca. 10) Method 11 chemistry + lo shear (b.fl. pH