SIST EN ISO 20427:2025

SLOVENSKI STANDARD
01-februar-2025
Pigmenti in polnila - Postopek disperzije za določanje porazdelitve velikosti delcev
na podlagi sedimentacije suspendiranih pigmentov ali polnil v tekoči fazi (ISO
20427:2023)
Pigments and extenders - Dispersion procedure for sedimentation-based particle sizing
of suspended pigment or extender with liquid sedimentation methods (ISO 20427:2023)
Pigmente und Füllstoffe - Dispergierverfahren zur sedimentativen
Teilchengrößenbestimmung von suspendierten Pigmenten oder Füllstoffen mit
Flüssigsedimentationsverfahren (ISO 20427:2023)
Pigments et matières de charge - Procédure de dispersion pour la granulométrie par
sédimentation d'un pigment ou d'une charge en suspension à l'aide de méthodes de
sédimentation en milieu liquide (ISO 20427:2023)
Ta slovenski standard je istoveten z: EN ISO 20427:2024
ICS:
87.060.10 Pigmenti in polnila Pigments and extenders
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 20427
EUROPEAN STANDARD
NORME EUROPÉENNE
August 2024
EUROPÄISCHE NORM
ICS 87.060.10
English Version
Pigments and extenders - Dispersion procedure for
sedimentation-based particle sizing of suspended pigment
or extender with liquid sedimentation methods (ISO
20427:2023)
Pigments et matières de charge - Mode opératoire de Pigmente und Füllstoffe - Dispergierverfahren zur
dispersion pour la détermination granulométrique sedimentativen Teilchengrößenbestimmung von
basée sur la sédimentation des pigments ou matières suspendierten Pigmenten oder Füllstoffen mit
de charge en suspension par des méthodes de Flüssigsedimentationsverfahren (ISO 20427:2023)
sédimentation dans un liquide (ISO 20427:2023)
This European Standard was approved by CEN on 19 August 2024.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.

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Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2024 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 20427:2024 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
The text of ISO 20427:2023 has been prepared by Technical Committee ISO/TC 256 "Pigments,
dyestuffs and extenders” of the International Organization for Standardization (ISO) and has been taken
over as EN ISO 20427:2024 by Technical Committee CEN/TC 298 “Pigments and extenders” the
secretariat of which is held by DIN.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by February 2025, and conflicting national standards
shall be withdrawn at the latest by February 2025.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
Any feedback and questions on this document should be directed to the users’ national standards body.
A complete listing of these bodies can be found on the CEN website.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland,
Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of
North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and the
United Kingdom.
Endorsement notice
The text of ISO 20427:2023 has been approved by CEN as EN ISO 20427:2024 without any modification.

INTERNATIONAL ISO
STANDARD 20427
First edition
2023-11
Pigments and extenders — Dispersion
procedure for sedimentation-based
particle sizing of suspended pigment
or extender with liquid sedimentation
methods
Reference number
ISO 20427:2023(E)
ISO 20427:2023(E)
© ISO 2023
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii
ISO 20427:2023(E)
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principles of dispersion. 3
4.1 Principles of ultrasonic dispersion . 3
4.2 Principle of wet jet mill dispersion . 3
4.3 Principle of shaker-based dispersion . 3
5 Principles of sedimentation-based techniques for particle size analysis .4
5.1 Stokesian sedimentation analysis . 4
5.2 Disk-type centrifuges . 4
5.3 Cuvette-type centrifuges . . 4
5.4 Gravitation-based sedimentation methods . 4
5.5 Centrifugal field-flow fractionation method . 5
6 Apparatus . 5
7 Settings for dispersion .7
7.1 Procedure of ultrasonic dispersion using a probe-type sonicator . 7
7.2 Procedure of ultrasonic dispersion using a bath-type sonicator . 8
7.3 Procedure of shaker-based dispersion . 8
8 Dispersion procedure . 9
8.1 General . 9
8.2 Sampling for dispersion. 9
8.3 Reagents . 9
8.4 Recommendations for sample preparation. 10
9 Sampling .10
10 Measurement and expression of results .10
11 Test report .10
Annex A (normative) Protocol for the determination of energy input .12
Annex B (informative) Limits for ultrasonic dispersion procedure .15
Annex C (informative) Procedures for dispersion of TiO pigments .16
Annex D (informative) Procedure for dispersion of CaCO with wet jet milling .17
Annex E (informative) Procedure for the dispersion of Fe O with an ultrasonic probe .18
2 3
Annex F (informative) Procedure for dispersion of carbon black .19
Annex G (informative) General procedure for dispersion of pigment or extender .20
Bibliography .22
iii
ISO 20427:2023(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO document should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
ISO draws attention to the possibility that the implementation of this document may involve the use
of (a) patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed
patent rights in respect thereof. As of the date of publication of this document, ISO had not received
notice of (a) patent(s) which may be required to implement this document. However, implementers are
cautioned that this may not represent the latest information, which may be obtained from the patent
database available at www.iso.org/patents. ISO shall not be held responsible for identifying any or all
such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
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expressions related to conformity assessment, as well as information about ISO's adherence to
the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see
www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 256, Pigments, dyestuffs and extenders.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
iv
INTERNATIONAL STANDARD ISO 20427:2023(E)
Pigments and extenders — Dispersion procedure for
sedimentation-based particle sizing of suspended pigment
or extender with liquid sedimentation methods
1 Scope
This document specifies sample preparation methods to determine the size distribution of separate
particles of a single pigment or extender, which is dispersed in a liquid by application of a standardized
dispersion procedure, using an ultrasonic device, shaker device or wet jet mill.
The sample preparation methods described are optimized for measurements carried out with a particle
sizing technique based on sedimentation. This technique relies on particle migration due to gravitation
or centrifugal forces and requires a density contrast between the particles and the liquid phase.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 3696, Water for analytical laboratory use — Specification and test methods
ISO 9276-1, Representation of results of particle size analysis — Part 1: Graphical representation
ISO 13317-1, Determination of particle size distribution by gravitational liquid sedimentation methods —
Part 1: General principles and guidelines
ISO 13317-2, Determination of particle size distribution by gravitational liquid sedimentation methods —
Part 2: Fixed pipette method
ISO 13317-3, Determination of particle size distribution by gravitational liquid sedimentation methods —
Part 3: X-ray gravitational technique
ISO 13317-4, Determination of particle size distribution by gravitational liquid sedimentation methods —
Part 4: Balance method
ISO 13318-1:2001, Determination of particle size distribution by centrifugal liquid sedimentation methods
— Part 1: General principles and guidelines
ISO 13318-2, Determination of particle size distribution by centrifugal liquid sedimentation methods —
Part 2: Photocentrifuge method
ISO 13318-3, Determination of particle size distribution by centrifugal liquid sedimentation methods —
Part 3: Centrifugal X-ray method
ISO 15528, Paints, varnishes and raw materials for paints and varnishes — Sampling
ASTM D5965, Standard Test Methods for Density of Coating Powders
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO 20427:2023(E)
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
nanoscale
length range from approximately 1 nm to 100 nm
Note 1 to entry: Properties that are not extrapolations from a larger size are predominantly exhibited in this size
range. For such properties, the size limits are considered approximate.
Note 2 to entry: The lower limit in this definition (approximately 1 nm) is introduced to avoid single and
small groups of atoms from being designated as nano-objects or elements of nanostructures, which can be
implied by the absence of a lower limit.
[SOURCE: ISO 80004-1:2023, 3.1.1 — modified, notes 1 and 2 to entry have been added.]
3.2
nanoparticle
nano-object with all external dimensions in the nanoscale (3.1) where the lengths of the longest and the
shortest axes of the nano-object do not differ significantly
Note 1 to entry: If the dimensions differ significantly (typically by more than three times), terms such as
nanofibre or nanoplate may are preferred to the term nanoparticle.
[SOURCE: ISO 80004-1:2023, 3.3.4, modified — "where the lengths of the longest and the shortest axes
of the nano-object do not differ significantly" has been added to the definition.]
3.3
agglomerate
collection of weakly or medium strongly bound particles where the resulting external surface area is
similar to the sum of the surface areas of the individual components
Note 1 to entry: The forces holding an agglomerate together are weak forces, for example van der Waals or simple
physical entanglement.
Note 2 to entry: Agglomerates are also termed secondary particles and the original source particles are termed
primary particles (3.5).
[SOURCE: ISO 80004-1:2023, 3.2.4]
3.4
aggregate
particle comprising strongly bonded or fused particles where the resulting external surface area is
significantly smaller than the sum of surface areas of the individual components
Note 1 to entry: The forces holding an aggregate together are strong forces, for example covalent or ionic bonds,
or those resulting from sintering or complex physical entanglement, or otherwise combined former primary
particles (3.5).
Note 2 to entry: Aggregates are also termed secondary particles and the original source particles are termed
primary particles (3.5).
[SOURCE: ISO 80004-1:2023, 3.2.5, modified — "or otherwise combined former primary particles" has
been added to the end of note 1 to entry.]
3.5
primary particle
single nano-object with at least one of three external dimensions at the nanoscale
Note 1 to entry: Sometimes, if the primary particle is present in crystalline form, it also contains twinning
boundaries.
ISO 20427:2023(E)
3.6
spin fluid
inert liquid which is injected into the disc of a disc centrifuge photosedimentometer prior to the sample
to define a certain radius dependent gradient of viscosity for sedimentation
Note 1 to entry: Alkaline conditions minimize agglomeration of dispersed aggregates in most cases.
3.7
wet jet milling
dispersing method of particles in liquid phase using the complex shear force arising from turbulent
flow in the channel and cavitation from the abrupt pressure change
Note 1 to entry: This method is also called high pressure homogenizer method.
4 Principles of dispersion
4.1 Principles of ultrasonic dispersion
A piezo electrical ceramic material is driven by an applied alternating current electrical field to expand
and shrink periodically at an ultrasonic frequency in the range of 15 kHz up to 80 kHz and more. This
movement creates acoustic waves moving through the dispersion, which produce cavitation bubbles.
The collapse of these cavitation bubbles leads locally to strong thermal effects and shear-stress, which
are responsible for the destruction of agglomerates and even aggregates.
Energy density of sonication, temperature and particle volume concentration of the dispersion are
critical parameters of sonication and should be held at recipe values strictly.
In addition to probe-type sonicators ultra sonic (US) baths, inverted cup-horn sonicators and so-
called vial-tweeters also exist. US baths, cup-horn dispersers and vial-tweeters are known as indirect
dispersers, where sound energy is inserted via the wall of the container. Determining the energy input
[9]
of these dispersers is much more difficult than for probe sonication, but contamination is reduced .
4.2 Principle of wet jet mill dispersion
The wet jet milling method is a wet-type milling to disintegrate agglomerates of powder samples in
liquid. In this method, particles suspended in a liquid medium are passed through a narrow channel
at high pressure. Then, the suspension of the particles is enhanced by the complex shear force arising
from turbulent flow in the channel. In addition, the high pressure in the narrow channel induces the
cavitation bubbles from the abrupt pressure change. The burst of the cavitation bubbles then work
to disperse powder samples in the liquid phase, as in the ultra-sonication method. The advantage of
this dispersion technique is that it yields suspensions with low contamination, unlike the ultra-sonic
homogenizer method. The pressure range is the important factor to disperse the powder samples in the
[10][11]
liquid phase. Typically, the pressure range is from 80 MPa to 245 MPa .
4.3 Principle of shaker-based dispersion
The shaker device should be built like a plate with holders for the high-density polyethylene (HDPE)
bottles (see Annex B). A successful dispersion is achieved when the plate is shaking vertically from back
to front with a vibration amplitude of minimum 32 mm and a frequency of 660 Hz.
Important aspects are:
— inclusion of grinding beads, high loading;
— particle dispersion limitations: agglomerates/aggregates <100 µm in a liquid (viscous medium);
— grinding beads are agitated by rotary, tumbling and/or 2D-vibratory motion of the container/vessel;
ISO 20427:2023(E)
— shear and elongational stress on agglomerates at squeezing of liquid between colliding grinding
[12][13]
beads and impulse exchange from collisions of agglomerates with grinding beads .
5 Principles of sedimentation-based techniques for particle size analysis
5.1 Stokesian sedimentation analysis
For all sedimentation-based procedures for particle sizing which are cited in this document, Stokesian
sedimentation analysis of dispersions is used. ISO 13318-1:2001, 4.1 describes in detail the general
procedure and calculations used to approach a particle size distribution of dispersed particles.
5.2 Disk-type centrifuges
The particles settle within an optically clear, rotating disc. When particles approach the outside edge
of the rotating disc, they block/scatter a portion of a light beam or X-ray beam that passes through
the disc. The change in light intensity shall be continuously recorded, and converted by the operating
software into a particle size distribution, in accordance with ISO 13318-1.
Instead of detecting the local particle concentration with optical turbidity, X-ray absorption shall be
used in certain instruments with the advantage of direct particle mass dependency, in accordance with
ISO 13318-3.
5.3 Cuvette-type centrifuges
The cuvette-type centrifuge is a special analytical centrifuge that instantaneously measures the
particle concentration at one or more radial positions within the rotating sedimentation cuvette.
For instance, space- and time-resolved extinction of the transmitted light across the entire length of the
sample allows the analysis of particle and droplet velocity distributions for creaming and sedimentation
phenomena without the need of any material data. This process additionally performs particle sizing
according to ISO 13318-2.
−1 −1
The centrifugal speed of these instruments is typically between 50 min and 60 000 min . Instruments
−1
with a centrifugal speed below 10 000 min are typically called cuvette centrifuges. Devices which
−1
can rotate above 10 000 min rotation are called ultracentrifuge. For centrifugal speeds greater than
−1
6 000 min , the detection of particle sizes is limited to 1 µm or below.
5.4 Gravitation-based sedimentation methods
The gravitation-based liquid sedimentation shall be executed using four different techniques: the fixed
pipette method in accordance with ISO 13317-2, the X-ray gravitation-based technique in accordance
with ISO 13317-3, the balance method in accordance with ISO 13317-4 and gravitation-based photo
sedimentation.
With the balance method as well as with the pipette method in accordance with ISO 13317-2, a
resolution below 1 µm is critical because of the limitations of the used detection mechanisms. The X-ray
sedimentation on the other hand depends on vibration isolation and detector quality. It can resolve
100 nm, similar to the photo sedimentation.
Therefore, only the liquid X-ray sedimentation in accordance with ISO 13317-1 and ISO 13317-3 is
included in this document.
The concentration of a dispersed sample is measured by the attenuation of an X-ray beam. A stable,
narrow, monochromatic collimated beam of X-rays passes through a suspension of the sample and
is detected at a known distance from the top of the sample cell. The sample cell is filled completely
with the sample suspension for the duration of the analysis. The settling height at which the particle
concentration is determined may be reduced during the analysis for the purpose of obtaining a more
rapid analysis compared to an analysis where all measurements are made at the same height value.
ISO 20427:2023(E)
The cumulative mass percentage of the sample present at a given sedimentation height is continuously
determined. The X-ray signal attenuation at the known height is compared to the attenuation in the
suspending liquid and also to the attenuation in the homogeneously dispersed sample present in the
liquid. The attenuation of the emergent X-ray beam is proportional to the mass of the powder in the
beam.
5.5 Centrifugal field-flow fractionation method
Field-flow fractionation is a flow-based separation methodology. Centrifugal field-flow fractionation
(CF3) is a separation technique that uses a centrifugal field applied perpendicular to a circular channel
that spins around its axis to achieve size separation of particles between the limits of 10 nm and
50 µm. In this method, separation is governed by a combination of size and effective particle density,
indicating that applicable size range is dependent on and limited by the effective particle density. In
CF3, the mobile phase and analyte flow longitudinally through the channel. The channel is designed to
separate the sample components along its length, resulting in the elution of constituents at different
times. The channel and its large aspect ratio are designed to promote parabolic or near-parabolic
laminar flow between two infinite planes under normal operational conditions. Fractionation is
achieved during passage through the channel, based on the velocity flow profile, after which the mobile
phase containing separated constituents exits to online detectors and/or a fraction collector for off-line
analysis. Common detectors used for analysis of pigment and extender include ultraviolet-visible (UV-
Vis) absorbance, fluorescence, multi-angle light scattering (MALS), dynamic light scattering (DLS) and
element detectors such as the inductively coupled plasma mass spectrometer (ICP-MS). Combinational
analysis of the sizing and concentration evaluation detectors, as well as the size distribution analysis
have been performed using this method according to ISO/TS 21362.
6 Apparatus
Use standard laboratory apparatus, together with the following.
6.1 Apparatus for ultrasonic dispersion
6.1.1 Probe-type sonicator, with at least 100 W power and a frequency of 10 kHz to 100 kHz.
This type of sonicator has been found to be an effective means of dispersing particulate materials
in liquid dispersion from agglomerates into discrete primary particles or/and aggregates. The
temperature of the dispersion during sonication should be held as low as possible, around typical room
temperature, in order to maintain conditions for good stability of the dispersing agents.
6.1.2 Bath-type sonicator, with at least 50 W power and a frequency of 10 kHz to 100 kHz.
6.2 Apparatus for wet jet milling dispersion
The apparatus for wet jet milling is designed to disperse, crush, emulsify and surface-modify the
[14][15]
material pressurized to a maximum of 245 MPa . This apparatus consists of various components
containing a high-voltage section and ultra-high-pressure section each. In the wet jet milling apparatus,
the powder suspension pressurized by the pressure intensifier is branched in the apparatus chamber
and accelerated by the nozzle in the chamber so that the dispersions collide with each other to achieve
micronization. The maximum jet pressure depends on the nozzle diameter. The typical values of the
nozzle diameter are from 0,05 mm to 0,15 mm. Materials with a particle diameter smaller than the
nozzle diameter can be applied in order to prevent the nozzle from becoming clogged. It is recommended
that the maximum particle diameter is smaller than half of the nozzle diameter. The apparatus should
be equipped with a leakage sensor. When a liquid leakage from the high-pressure cylinder is discovered,
the instrument stops the milling. The typical handling amount is about 0,1 l/min and the applicable
solvents for this system are both organic and aqueous solvents. However, it is recommended to use
water as solvent in principle; using organic solvent such as acetone, alcohol, acid or alcohol can influence
sealing sections of apparatus for wet jet milling.
ISO 20427:2023(E)
WARNING — Ignoring safety precautions and wrong handling or operation can cause serious or
minor injuries and damage to this apparatus or other properties.
WARNING — Do not operate the apparatus with the solvent boiling point exceeded. Blow-off of
the material or solvent caused by bumping or equipment damage caused by high-pressure steam
can injure the body.
See Annex D for an example of a detailed procedure of wet jet milling dispersion, as well as a detailed
description for energy estimation.
1)
6.3 Apparatus for shaker-based dispersion, such as Disperser DAS .
6.4 Analytical balance, accurate to the nearest 0,1 mg.
3 3
6.5 Beaker, based on the sonicator size, 50 cm to 300 cm tall-form.
6.6 Magnetic stirring device with stirrer bar
3 3 3 3
6.7 Syringes, 1 cm , 2 cm , 10 cm and 20 cm or better corresponding pipettes.
6.8 Cooled bath
6.9 Liquid sedimentation-based detection systems for particle size measurement
Table 1 and Table 2 show liquid sedimentation-based device examples for measuring instruments which
are available at the time of publication of this document.
Table 1 — Examples for currently available measuring instruments
Type Photo-centrifuge X-ray-centrifuge Analytical ul-
tra-centrifuge
Disc centrifuge Cuvette centri- Disc centrifuge Cuvette centri-
fuge fuge
Wavelength 405 nm or 470 nm Multiple wave- Data to be deliv- Optical
or 650 nm lengths ered from appara-
multiple wave-
tus manufacturer
405 nm to 870 nm lengths or xenon
light
−1 −1 −1
Acceleration range 600 min to 500 min to 600 min to (middle of cell)
−1 −1 −1
at the bottom 24 000 min 4 000 min 18 000 min −1
1 000 min to
5 times to 2 300 −1
Not preferred: 60 000 min
times earth grav-
Rotation speed
ity
(at cell bottom)
Type of detection Light extinction Light extinction X-ray extinction Light extinction
versus time versus time and versus time or refractive index
position versus time
Sample volume 100 µl to 400 µl 100 µl to 2 000 µl 100 µl to 400 µl 350 µl to 400 µl
Typical sample 0,01 % to 10 % 0,01 % to 20 % 0,1 % to 30 % 0,01 % to 1 %
concentration in (volume fraction) (volume fraction) (mass fraction)
volume
Spin fluid volume 10 ml to 20 ml - 10 ml to 40 ml -
Number of sam- 1 Up to 12 1 Up to 14
ples
1) Disperser DAS is an example of a suitable product available commercially. This information is given for the
convenience of users of this document and does not constitute an endorsement by ISO of this product.
ISO 20427:2023(E)
TTabablele 1 1 ((ccoonnttiinnueuedd))
Type Photo-centrifuge X-ray-centrifuge Analytical ul-
tra-centrifuge
Disc centrifuge Cuvette centri- Disc centrifuge Cuvette centri-
fuge fuge
Sample contain- Disc rotor Disposable or Disc rotor Re-usable cells
ment reusable cells
Temperature No 4 °C to 60 °C No 0 °C to 40 °C
control (±0,5 °C) (±0,5 °C)
Range of particle 5 µm to 50 nm 500 µm to 50 nm 5 µm to 50 nm 800 nm to 2 nm
size
Table 2 — Examples for currently available measuring instruments
Type X Ray Cuvette Sedi-balance X-ray Cuvette sedi- CF3
sedimentation – mentation
movable cuvette
Test methods in
ISO 13317-3 ISO 13317-4 ISO 13317-3 ISO/TS 21362
accordance with
Wavelength / ex- O,138 nm / 0,071 nm / Optical
−15 −15
citation energy 1,442·10 J 2,801·10 J
multiple wavelengths
(9 keV) (17,48 keV)
are available
−1
Acceleration range - - - 0 min to
−1
at the bottom 12 000 min
Not preferred:
Rotation speed
Type of detection X-ray extinction computational X-ray extinction versus Light scattering
versus time detection using a time and space STEP
UV-Vis absorption
commercial balance (space- and time-re-
Refractive index
solved extinction
Fluorescence
profiles) Technology
ICP-MS
Sample volume 80 ml 1 l 0,2 ml to 1,6 ml 20 µl to 100 µl
Min. Sample con- 2,5 % mass density 2,5 % density de- 2 % mass density Dependent on the
centration in mass dependent pendent dependent samples
or volume
Number of samples 1 1 1 1
Sample contain- glass beaker class cylinder cuvette, different Flow channel
ment beaker materials
Temperature con- Yes No No No
trol
Range of particle 1 mm to 100 nm 1 mm to 5 µm 1 mm to 200 nm 40 µm to 10 nm
size
7 Settings for dispersion
7.1 Procedure of ultrasonic dispersion using a probe-type sonicator
Ultrasonic sources other than probe-type ones are not recommended and can lead to wrong results
because of the principle difficulties to calibrate the energy input.
The typical procedure is the following:
— fill beaker with a corresponding mass of water, depending on the size of the beaker;
ISO 20427:2023(E)
— place beaker in the insulating foam;
— put the ultrasonic probe and thermometer with short response-time in the water;
— the probe should be immersed in the same depth as later for dispersion;
— wait for thermal equilibration;
— the start temperature should be in defined, narrow range (e.g. between 20 °C and 25 °C);
— start ultrasonication.
It is important to keep the temperature constant. Cooling is recommended.
It is important to use the correct energy density to disintegrate the particulate sample. Setting the
energy density too low can lead to remaining agglomerates. If the energy density is too high, the
piezo ceramic sonicator can be destroyed and can contaminate the dispersion with nanoparticles. In
addition, a destruction of the particulate material can occur when using energies which are too high. In
some cases, the treated material can lose its pigmentary or extender properties when energy density
treatments are too high.
The energy estimation shall be calculated in accordance with Annex A.
7.2 Procedure of ultrasonic dispersion using a bath-type sonicator
It is important to use the correct energy density to disintegrate the particulate sample. Setting the
energy too low can lead to remaining agglomerates. In addition, a destruction of the particulate
material can occur when using energies which are too high. In some cases, the treated material can lose
its pigmentary or extender properties at energy treatments which are too high.
Carry out an energy density estimation similar to the procedure for a probe-type sonicator specified
in Annex A. Consider the warming of the whole bath together with the beaker. For weak sonicators,
enhance the time of sonication until temperature changes are measurable.
The procedure is similar to the procedure of ultrasonic dispersion using a probe-type sonicator (7.1),
except that the beaker is put into an ultrasonic bath:
— weigh out 0,1 % to 1,0 % (mass fraction), depending on the type of pigment or extender, in a 50 cm
to 300 cm tall-form beaker, depending on the size of the ultrasonic bath;
— fill the beaker with a corresponding mass of water, depending on the size of the beaker;
— place the beaker in a cooled bath to prevent heating above 40 °C. the upper limit of the temperature
shall be defined depending on the types of pigments or extenders;
— wait for thermal equilibration;
— the start temperature should be in defined, narrow range (e.g. between 20 °C and 25 °C);
— start ultrasonication.
It is important to always put the dispersion at the same geometric position with the same amount of
bath water to ensure it remains reproducible and to maintain homogenous mixing inside the beaker.
7.3 Procedure of shaker-based dispersion
The typically used device (6.3) shakes small bottles filled with dispersion in a vertical direction.
Typically, between 1 and 30 bottles can be put into a bottle holder. They are fixed between a platform
and a stamp coming from above. During dispersion, the whole platform is shaken oscillatory in a
vertical direction.
ISO 20427:2023(E)
To enhance the dispersion properties, milling beads should be inserted into the bottles. Typically, the
effectivity of dispersion is correlated to the shaking speed, the volume percent of milling beads and the
particle sizes as well as to the material of the milling beads.
The procedure is as follows:
— Take one 15 ml HDPE screw cap bottle and fill in the following dispersion: 12,475 ml dispersion
having 5 % to 20 % of particle volume concentration in aqueous solution together with the particle
amount adopted dispersant e.g. 5 g TiO in 7,475 g H O and 0,025 g hexametaphosphate (HMP) or
2 2
other polyphosphate;
— add 28 g ZrO milling particles (0,5 mm);
— put the bottle into a shaker (6.3)
— select energy input to 60 W/(ml × min);
— shake the bottle for 5 min.
If the energy cannot be adjusted, measure energy input per minute and adopt the shaking time to
300 W/ml. A detailed description for the energy estimation is given in Annex A.
8 Dispersion procedure
8.1 General
The dispersion process is dependent on the operation time, power and dimension of dispersion devices.
To optimize the operation, it is recommended to find the operation level which achieves stable size
distribution. For appropriate dispersing of pigment and extender, the choice of the liquid phase and
dispersant are also critical.
8.2 Sampling for dispersion
Select pigment or extender samples from larger-sized lots at random, in either pelletized or non-
pelletized form, in accordance with ISO 15528. Label and retain samples for storage or further analysis.
8.3 Reagents
Unless stated otherwise, use only reagents of recognized reagent grade.
8.3.1 Water, distilled or deionized, quality 3 in accordance with ISO 3696.
The water shall be free of particles. To ensure this, filtration shall be used (e.g. membrane filter - cut-
size 50 nm or smaller). Similar filtration shall also be used for any added additional solvents.
The liquids used shall not solve the particles to be measured.
If no data are available, the water shall be qualified by a blind test particle measurement in accordance
with this document.
8.3.2 Organic solvent, free of nanoparticles when measured in accordance with this document.
If no data are available, the solvent shall be qualified by a blind test particle measurement in accordance
with this document. If used, a blind measurement shall be performed in accordance with this document
using water, solvent and surfactant together in the planned concentrations.
The liquids used shall not solve the particles to be measured.
ISO 20427:2023(E)
8.3.3 Surfactant, free of nanoparticles when measured in accordance with this document, in relation
to the surface properties of the pigment of extender particles.
If no data are available, the surfactant shall be qualified by a blind test particle measurement in
accordance with this document. If used, it is important to make some blind measurement in accordance
with this document using water, solvent and surfactant together in the planned concentrations.
8.4 Recommendations for sample preparation
Examples of procedures for different materials are given in Annexes C, D, E and F. For other materials,
an example of a procedure is specified in Annex G.
9 Sampling
Select pigment or extender samples from larger-sized lots at random, in either pelletized or non-
pelletized form, in accordance with ISO 15528. Label and retain samples for storage or further analysis.
10 Measurement and expression of results
Perform the particle sizing using sedimentation methods in accordance with ISO 13317-1, ISO 13317-2,
ISO 13317-3, ISO 13317-4, ISO 13318-1, ISO 13318-2 or ISO 13318-3. One of these methods shall be
performed at least three times for each dispersion. Express the volume based on the average of the
volume-weighted particle size distributions as the cumulative function and as the transformed density
function in accordance with ISO 9276-1. In addition, the results of the particle size distribution (PSD)
measurement shall be presented as numbers in a table containing the single measurement results and
the resulting average values
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