Change search
ReferencesLink to record
Permanent link

Direct link
Aggregation of inkjet ink components by Ca and Mg ions in relation to colorant pigment distribution in paper
SP Technical Research Institute of Sweden - Chemistry, Materials and Surfaces, Sweden .
KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science. SP Technical Research Institute of Sweden - Chemistry, Materials and Surfaces, Sweden .
Show others and affiliations
2014 (English)In: Colloids and Surfaces A: Physicochemical and Engineering Aspects, ISSN 0927-7757, Vol. 456, 92-99 p.Article in journal (Refereed) Published
Abstract [en]

Papers coated with salts containing divalent cations exhibit superior inkjet print quality, which has been suggested to be due to fast aggregation of the colorant pigments close to, or even on, the surface of the paper. In this work we show the pivotal role of the carboxylic acid containing dispersing polymer. We report a series of aggregation and sedimentation experiments with commercial inks, generic ink formulations and specific ingredients comprising these formulations, and find differences in their response to the presence of MgCl2 or CaCl2. In particular, flocs and sediments formed in the presence of MgCl2 are denser than those formed in the presence of CaCl2. These differences are not predicted by the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory. We suggest that ion specific interactions occurring between Mg2+ or Ca2+, and charged carboxylate groups residing on the dispersing polymers, provoke the observed behavior.

Place, publisher, year, edition, pages
2014. Vol. 456, 92-99 p.
Keyword [en]
Inkjet, Pigment based inks, Confocal Raman microscopy, Aggregation, Dispersing polymer, Rheology
National Category
Physical Chemistry
URN: urn:nbn:se:kth:diva-150517DOI: 10.1016/j.colsurfa.2014.05.023ISI: 000340318000013ScopusID: 2-s2.0-84901642565OAI: diva2:747070

QC 20140915

Available from: 2014-09-15 Created: 2014-09-05 Last updated: 2014-10-02Bibliographically approved
In thesis
1. Spontaneous imbibition and colloidal aspects of inkjet printing
Open this publication in new window or tab >>Spontaneous imbibition and colloidal aspects of inkjet printing
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Water-based inkjet is one of the most abundant and versatile digital printing technologies. The subject of this thesis work is processes that take place once an inkjet drop lands on the surface of a porous printing media, with focus on liquid penetration due to capillary action (spontaneous imbibition) and aggregation of ink components. Knowing the details of these two sub-processes would allow optimization of printing processes as well as prediction of the final print result, based on material properties.

The dynamics of drops as they land on different surfaces is captured at adequate time and length-scales by an optical imaging system coupled to an inkjet dispensing unit. The evaporation rate of drops is quantified and distinguished from imbibition, and their spreading behavior on porous substrates is characterized. A set of paper grades is used as examples to conclude that the events are captured accurately. Scaling laws for imbibition are derived from Darcy’s law for liquid flow through dimensional analysis and it is shown that the imbibition rate of drops is related to dimensionless volume and time groups, defined by the volume of the drop, porosity and permeability of the substrate, viscosity of the liquid and the Laplace capillary pressure that drives the imbibition. The approach is applied for two types of systems, one that includes simple liquids imbibing homogeneous and isotropic porous glass and the other that includes complex liquids imbibing heterogeneous and anisotropic paper.

The addition of simple divalent salts to the paper surface is widely used to increase the print quality of water-based pigmented inkjet inks. Salt ions quickly diffuse into the inkjet droplets as they land on the paper and cause the ink to aggregate. This effect leads to the accumulation of colorant-pigments close to, or even on, the surface of the paper. Two salts, CaCl2 and MgCl2, are used to aggregate inkjet inks and their components. The interactions between the aggregated compounds are investigated by a set of experimental measurements that include sedimentation, confocal Raman microscopy, turbidity, rheology and electrophoretic mobility. It is concluded that the salt induced aggregation is led by a non-color polymeric ink component used as a pigment dispersant, and that CaCl2 induces stronger interactions between polymeric carboxylate groups compared to MgCl2. This ion specific effect cannot be explained by the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory for electrostatic interaction in colloidal systems.

Place, publisher, year, edition, pages
Stockholm,Sweden: KTH Royal Institute of Technology, 2014. xx, 69 p.
TRITA-CHE-Report, ISSN 1654-1081 ; 2014:39
National Category
Chemical Sciences
urn:nbn:se:kth:diva-152904 (URN)978-91-7595-272-7 (ISBN)
Public defence
2014-10-24, Q2, Osquldas Väg 10, KTH, Stockholm, 11:56 (English)

QC 20141002

Available from: 2014-10-02 Created: 2014-10-02 Last updated: 2014-10-02Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full textScopus

Search in DiVA

By author/editor
Oko, AsafSwerin, AgneClaesson, Per M.
By organisation
Surface and Corrosion Science
In the same journal
Colloids and Surfaces A: Physicochemical and Engineering Aspects
Physical Chemistry

Search outside of DiVA

GoogleGoogle Scholar
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Altmetric score

Total: 68 hits
ReferencesLink to record
Permanent link

Direct link