Colloids and Surfaces A: Physicochem. Eng. Aspects 326 (2008) 61–66

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Colloids and Surfaces A: Physicochemical andEngineering Aspects
journal homepage: www.elsevier.com/locate/colsurfa

Approach for detecting localization of inkjet ink components
using dynamic-SIMS analysis
Masaya Shibatani a,b,∗ , Tsutomu Asakawa c , Toshiharu Enomae a , Akira Isogai aaPaper Science Laboratory, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Japan
IJ Industrial Applications R&D Department, Production Engineering & Development Div., Seiko Epson Corporation, Japanc
Material Analysis & Research Center, R&D Department, Seiko Epson Corporation, Japanba r t i c l e

i n f oArticle history:
Received 3 August 2007
Received in revised form 15 May 2008
Accepted 18 May 2008
Available online 29 May 2008
Keywords:
InkjetSIMS
Pigmentink
Glycerina b s t r a c t
Organic compounds having high boiling points included in inkjet inks remain in the printed media after
printing. It has been said that these residual organic compounds inﬂuenced the fastness of pigment ink
prints, but details of the analytical methods have not been reported, yet. In this paper, a new analyticalmethod was applied for detecting localization of those organic compounds in inkjet prints after printing.
Glycerin was chosen as a typical example of those organic compounds. To analyze the position within theprinted paper, deuterated glycerin was formulated in the ink as a probe and dynamic secondary ion mass
spectroscopy (SIMS) was applied to detect the deuterium peak in the whole printed paper thickness. It
was found that glycerin remained in the range from the bottom of the pigment ink layer to the pigment
coating layer of the printed media. This peak was sufﬁciently detectable for at least 7 days after printing.
The maximum peak of residual glycerin was located at the surface of the coating layer of paper. In addition,
existence of a ﬁlter cake of pigment ink discussed in other work was not conﬁrmed in this study.
© 2008 Elsevier B.V. All rights reserved.

1. Introduction
Inkjet inks generally contain organic solvents with high boilingpoints [1]. The solvent is added to the ink to ensure stable delivery of the ink and to prevent nozzle clogging in inkjet systems.
The solvent does not evaporate at room temperature and is thus
considered to remain in the printed samples. Therefore, it has been
indicated that the solvent affects the preservation of printed imagesby changing the chalking resistance (scuff resistance) [2]. Although
the properties of the solvent have been evaluated by various
qualitative analytical methods [3,4], the quantitative relationshipbetween the residing characteristics and the chalking resistancehas not been studied. In past works, the correlation between
the residence behavior and the chalking resistance was examinedby applying glycerin, which is a common high-boiling-point solvent. The amount of residual glycerin in paper was analyzed byusing pyrolysis–gas chromatography (Py–GC) [5]. However, in thismethod, the ink layer on the paper is abraded and the obtained powder is analyzed as a bulk sample. Thus, it is impossible to specify thelocation of the high-boiling-point solvent. Another problem is thata wet ink ﬁlm solidiﬁes with time, which makes abrasive sampling
difﬁcult. To solve these problems, the analysis of printed material
by using secondary ion mass spectroscopy (SIMS) is considered [6].
However, the SIMS method has been applied only for analyzing
the thickness range of solid constituents containing labeled metallic elements and has never been applied for analyzing the depth
distribution of organic compounds containing labeled elements.
In this study, we report on the local distribution of glycerinthroughout the ink layer and the paper coating layer. Inks containing deuterated glycerin – d8 glycerin – in which all the hydrogenatoms are replaced with deuterium atoms were prepared, andsamples printed using these inks were analyzed along the depth
direction by using SIMS. The local distribution of the glycerin wasshown by observing the ion intensity of deuterium in the secondary
ions. The advantage of this analytical technique is that the local distribution of glycerin in the ink layer and at the boundary with thepaper coating layer can be observed directly.

2. Experimental
2.1. Preparation of inks and samples∗ Corresponding author at: IJ Industrial Applications R&D Department, Production
Engineering & Development Div., Seiko Epson Corporation, Japan.
Tel.: +81 266 626813.
E-mail address: Shibatani.Masaya@exc.epson.co.jp (M. Shibatani).
0927-7757/$ – see front matter © 2008 Elsevier B.V. All rights reserved.
doi:10.1016/j.colsurfa.2008.05.033

Ink containing the following constituents was prepared: 6%
solid pigment (quinacridone-magenta: C.I. PR122 and copper
phthalocyanine-cyan: C.I. PB15:3), 22% d8 glycerin (Euriso-top Co.),

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15% glycerin (Kanto chemical Co.), 0.4% nonionic surface-active
agent (Air products Inc.), and 56.6% pure water. This ink was
loaded into a commercial inkjet printer and the output samples
were evaluated. A solid-printed sample with 31 g/m2 of ink was
introduced into a temperature-programmed desorption mass spectrometer (TDS). For the SIMS analysis, a linear continuous patternof single dots (each from one droplet of 20 pL, EPSON SC900) was
printed on a sheet of paper, which was then subjected to evaluation.
Paper samples A and B were prepared from commercially available
resin coat-based and photo-grade glossy paper for general inkjet
printers.
2.2. SIMS analysis
Sector-type SIMS, Imf4, at Cameca, France was used with cesium(Cs) as the primary ions. After the sample surface was coated withplatinum (Pt), it was analyzed in the high mass-resolution modeusing a primary bias ion voltage of −14.5 kV and an ion currentof 10 nA. The diameter of the analyzed circular area was 33 ␮m,located at the center of an abraded area of 100 ␮m × 100 ␮m.
The etching of the sample was started after evacuation for
30 min.
2.3. Temperature-programmed desorption mass spectromete r(TDS)
The mass spectrum of the gases emitted into vacuum atroom temperature (22–24 ◦ C) was analyzed by a commercial temperature-programmed desorption mass spectrometer,
EMD-WA1000K, ESCO, Japan. The evaporated pressure was
1.59 × 10−9 KPa.

Fig. 1. Volatility of ink set on paper measured by mass spectroscopy during temperature programmed desorption.

under high-vacuum conditions. In this analysis, the existence ofglycerin under high vacuum and room temperature (between 22 ◦ C
and 24 ◦ C) was determined. Fig. 1 shows the changes in several
mass spectrum peaks with time for the printed and the blank
paper A samples. The intensity of the glycerin peaks appearing
regularly at m/z = 92 was constantly zero for the printed samples
as well as the blank sheet. In the spectra for both the printed

2.4. Surface proﬁle measurement
The thickness of the ink layer on the paper and the depth of thehole made by SIMS were measured by using a contact-type stylus
proﬁlometer, Tencor P-15, KLA, USA.
2.5. Observation by FIB-SEM
Analyses using a focused ion beam (FIB) (FB-2000) in combination with a scanning electron microscope (SEM) (S-5000) were
performed. These instruments, manufactured by Hitachi Ltd., Japan,
were used at an acceleration voltage of 5 kV. Before performing
FIB cutting, the sample surfaces were coated with Pt and carbon(C). Surface observations of paper samples was performed at anacceleration voltage of 10 KV.
2.6. Particle size distribution
Particle sizes of pigment was observed by laser diffractometry
method, UPA150, Microtrac Ltd.
3. Results
3.1. Preliminary analysis by temperature-programmed desorption
mass spectrometer
Before introducing a printed sample to the high-vacuum conditions (10−8 to 10−9 KPa) of SIMS, it must be conﬁrmed thatno glycerin evaporates from the sample. The preliminary analysis of the evaporation of glycerin was carried out by using atemperature-programmed desorption mass spectrometer, which
is an apparatus that performs qualitative analysis by measuring
the mass spectrum of a sample as it is heated and decomposed

Fig. 2. Scanning electron micrographs of paper A and B with large voids on surface
indicated by arrows.

M. Shibatani et al. / Colloids and Surfaces A: Physicochem. Eng. Aspects 326 (2008) 61–66

Fig. 3. Particle size distribution of ink pigment determined by laser diffractometry
method.

and blank samples, the detected peaks at m/z = 18 and 17 are
attributed to water (H2 O) and the hydroxyl ion (OH), respectively.
They are generated from the water contained in the paper underthe vacuum conditions. The peaks at m/z = 18 remained at a plateau
until approximately 30 min from the beginning because the signal
overshot the detection range. Based on this measurement, it was
conﬁrmed that the glycerin in the printed samples does not evaporate and can be analyzed under high-vacuum conditions by using
SIMS.

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Fig. 5. Surface proﬁle of magenta ink dot on paper A.

3.3. Analysis by SIMS

Fig. 2 shows photographs of paper samples A and B. It is observedthat both the samples have void structure and particles of silica pigment are round and less than 30 nm in diameter. Large voids wereformed in places as indicated by arrows. However, particle diameter of ink pigments were distributed approximately 50–400 nm asshown in Fig. 3. This fact indicates that most of ink pigment particles are not possible to intrude into voids between silica particles,
but partly possible to drop into large voids on the paper surface.

3.3.1. SIMS analysis of samples using magenta ink
Fig. 4 shows the result of the SIMS analysis of a sample on whicha linear continuous pattern is drawn with magenta ink containing
d8 glycerin. Figs. 5 and 6 show the height of the ink layer and thedepth of the hole produced by SIMS, as measured by the contacttype proﬁlometer, respectively. The thickness of the ink layer andthe depth of the hole are estimated to be approximately 0.25 and1.8 ␮m, respectively. Figs. 7–9 show the results of the SIMS analysis
as a function of the time after printing. SIMS etches the pigment
ink layer by spattering Cs ions along the z-direction perpendicular
to the paper plane and carries out time-resolved detection of secondary ions. The secondary ions focused on in this work included
six species: 13 C, 1 H, 2 H, 18 O, 63 Cu, and 30 Si. The 13 C, 1 H, and 18 O
secondary ions were included in the pigment quinacridone, thebinder of the coating layer, and the high-boiling-point organic compounds. On the other hand, a part of the 18 O and all of 30 Si ions were
included in the silica used as the coating layer of the paper sample. In the ﬁgures, the vertical axis represents the secondary ion
intensities and the horizontal axis, the spattering time. The data at
0 s correspond to information about the top surface of the sample.

Fig. 4. Surface photograph of the sample by SIMS analysis.

Fig. 6. Depth proﬁle of magenta ink dot on paper A after etching.

3.2. Surface analysis of paper samples and particle size of ink
pigments

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Fig. 7. Intensity of secondary ions from magenta ink dot on paper A 24 h after
printing.

Fig. 9. Intensity of secondary ions from magenta ink dot on paper A 7 days after
printing.

To avoid charging in the ion beam, the top surface of the sample iscoated with Pt in advance. Therefore, little sample information isprovided by the data obtained in the time range 0–60 s because thesignals are generated in the Pt layer. After approximately 60 s, thePt layer is passed and the top surface of the ink layer is exposed.
The depth range of 60–300 s corresponds to the quinacridone layer
because the intensities of 13 C and 1 H are constant. The secondary
ion intensities of 13 C and 1 H have their ﬁrst inﬂection points at
approximately 300 s, and then decrease for 300–500 s constantly.
They also have a second inﬂection point at approximately 500 s, andthen they decrease gradually until the end. On the other hand, theintensity curve of 30 Si has its ﬁrst inﬂection point at approximately
200 s; subsequently, it has a second inﬂection point at approximately 400 s, which remains constant after 500 s until the end. The
secondary ion 18 O is included in the quinacridone, glycerin, and silica of the coating layer. The intensity of 18 O has its ﬁrst inﬂection
point at approximately 200 s and a faint second inﬂection point
at approximately 450 s, which decreases slightly after 500 s. This
result shows that the depth range of 200–500 s is not a clear boundary (NCB range). Small ink-pigment particles may intrude into themicropores of the coating layer of the paper sample because there isno distinct transition in the 18 O intensity curve in this time range.
In this analysis, the ion intensity of deuterium (2 H) is importantbecause it represents the glycerin distribution. Glycerin consists of
C, H, and O. Sector-type SIMS cannot distinguish between the ions of
non-deuterated glycerin and the ions of other organic compounds.
However, as deuterated glycerin is used in this analysis, it can besaid that the ion intensity of 2 H corresponds to that of glycerin. The
natural abundance ratio of 2 H is 0.015%, and the ion intensity of 2 H
in glycerin clearly differs from that of natural 2 H. The backgroundnatural 2 H intensity was below 1.0 × 10−8 . The peaks of 2 H corresponding to concentrated glycerin can be observed in the depth
range of 200–500 s, which is the NCB range for this paper sample.
Most of the glycerin present in the magenta ink is found in thisrange. This indicates that there is some shielding effect acting on
glycerin when it is transferred from the ink layer to the paper coating layer. The intensities of 30 Si and 18 O become constant after 500 s,
but the intensities of 13 C and 1H decrease after 500 s, at a constantrate. It is supposed that the paper coating layer has an over coatof resin components, which are contained in the coating layer or

Fig. 8. Intensity of secondary ions from magenta ink dot on paper A 48 h after
printing.

Fig. 10. Intensity of secondary ions from magenta ink dot on paper B 24 h after
printing.

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65

Fig. 13. Intensity of secondary ions from cyan ink dot on paper A 24 h after printing.
Fig. 11. Intensity of secondary ions from magenta ink dot on paper B 48 h after
printing.

the formulated amount of the resin components are different fromthose in the bulk coating layer in the paper surface. To enhance
the smoothness and hardness of the paper surface, post-treatment
processes have been reported to be conducted in the production ofcommercial inkjet photo paper [7]. Therefore, it was possible thatthe resin components on the paper surface block the penetrationof glycerin. At the same time, both the 30 Si and 18 O curves also had
peaks at approximately 400 s. Hence, it was supposed that there
is another coating layer with a high ratio of silica on the surfaceof the paper sample; however, from the observation of the crosssection of the coating layer (Fig. 15), there is no evidence of sucha silica layer over the paper surface. This suggests that some othermaterial containing silica is coated on the paper surface.
Figs. 10 and 11 show the SIMS analysis results for paper sample B. Comparing this result with that for paper A, we observe that
paper B has more residual glycerin. This tendency is the same asthat in the previous analysis results using the Py-GC method [5].
It appears that the difference in the diffusion rate due to the prolonged wetting of glycerin over the coating pore surfaces causes

Fig. 12. Comparison in intensity of 2H ions from magenta dot between paper A
and B.

the difference in the residual glycerin distribution. In other words,
the lower the wetting ability of glycerin over the coating pore surfaces, the more is the residual glycerin in the NCB range. Fig. 12shows the relative intensities of 2 H to 13 C for both the papers at 24
and 48 h after printing. The peak of the residual glycerin distribution appears to be located in the NCB range. As observed from thepeak shifts of approximately 450 s during the etching time and thedecreased peak heights, the glycerin penetrated the coating layer
during the second 24 h. In addition, the peak locations of 2 H for boththe paper samples were different because of the different etchingrates.
3.3.2. SIMS analysis of samples using cyan ink
Fig. 13 shows the result of the SIMS analysis for the sample
printed with cyan ink containing d8 glycerin. The measurement
was made 24 h after printing. Since the cyan ink contains C.I. PB15:3
as a pigment, the behavior of both the 63 Cu ions and the residual
glycerin can be observed. As shown in Fig. 14, the thickness of thecyan ink layer is 0.5 ␮m approximately twice that of the magenta
ink layer. In comparison with the amount of residual glycerin in
the magenta ink layer (Fig. 7), the amount of residual glycerin in
the cyan ink layer is smaller and that in the paper coating layer islarger. The reason for the smaller amount of residual glycerin in

Fig. 14. Surface proﬁle of cyan ink dot on paper A.

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The calculated porosity of magenta ink layer is 45.7% but that of
the cyan one is 78.6%; hence, the porosity of the cyan ink layer isabout 1.7 times larger than that of the magenta ink layer. The existence of a micro-ﬁlter cake at the bottom of the ink layer and at
the boundary with the paper coating layer has been discussed in
the references [8,9]. A transient increase in the intensity of the 63 Cu
ion is observed at the boundary, but an increase in the intensities of
13 C and 1 H ions is not observed. Therefore, the existence of a microﬁlter cake is not clearly conﬁrmed. Moreover, the SEM image of thecross-section of the cyan dot shown in Fig. 15 indicates the absenceof a ﬁlter cake layer at the boundary.
4. Conclusion
Ink-jet paper samples printed with inks containing d8 glycerin, namely that with all the hydrogen atoms replaced with
deuterium atoms, as a stable-isotope-labeled compound was analyzed by using SIMS. The distribution of residual glycerin along
the z-direction of the samples was obtained. This method could
be applied to other printing methods such as offset printing
using high-boiling-point solvents. Residual glycerin was locally distributed in the ink layer and at the boundary with the paper coating
layer. Furthermore, the existence of a pigment ﬁlter cake could not
be conﬁrmed.
References

Fig. 15. Cross-section image of cyan ink dot on paper A.

the cyan ink layer is unclear. However, it is considered that glycerin
cannot be retained in the cyan ink because half the height of thecyan ink dot implies that the cyan ink layer has more pores thanthe magenta ink layer for equal amounts of pigment in the inks.

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