preface
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ISO 21683-2019 “Release of simulated nano-objects from paints, varnishes, and tinted plastics in pigments and fillers determination experiments”

introduce
Nanoobjects (nanoscale pigments and fillers) may be released from paints, varnishes and tinted plastics into the surrounding air or liquid, which is an important health and safety consideration for the end user and the environment. Therefore, it is important to obtain data on the tendency of tinted coatings and plastics to release nanoobjects so that exposure can be assessed, controlled and minimized [10]. The properties may depend on the physical and chemical properties of the nano-object and the matrix containing the nano-object.

The methods currently available to assess the tendency of pigments, varnishes and plastics to release nano-objects into the air require energy to be applied to the sample to induce wear, erosion or comminentation, which causes the particles to diffuse into the gas phase, i.e., produce aerosols.

Due to its high sensitivity, particle number concentration and quantity weighted particle size distributions are necessary to quantify the release of nano-objects, because particle mass depends on cubic particle size and the mass concentration of nano-objects is too low to detect them with currently commercially available instruments. Further measurements, such as total particle surface concentration, such as references [11] and [12], may help explain, for example, health aspects. If the shape, morphology, porosity, and density of the granular material is known, it can be accurately converted to different quantity types by measuring the total particle size distribution.

In addition to selecting the appropriate measuring instrument, a quantitative assessment of process-induced particle release requires detailed information about the sample, the stresses introduced, and the type of interconnection with the instrument. Figure 1 shows, for example, the single stages that need to be considered when quantitatively characterizing particulate matter release in the air.

1 range
This document specifies a method for experimentally determining the release of nanoscale pigments and fillers into the environment under mechanical stresses of paints, varnishes and tinted plastics.

The method is used to assess whether and how many particles of defined size and distribution are released from the surface and released into the environment under stress (type and height of applied energy).

Samples are aged, weathered or otherwise conditioned to simulate the entire life cycle.

2 Normative references
The following files are referenced in the text in such a way that some or all of the content constitutes the requirements of this document. For dated references, citation-only versions apply. For undated references, the new version of the reference (including any revisions) applies.

ISO 9276-1, Representation of the results of particle size analysis – Part 1: Graphical representation

ISO/TS 80004-1, nanotechnology — Vocabulary — Part 1: Core terminology

ISO/TS 80004-2, nanotechnology — Vocabulary — Part 2: Nano-objects

ISO 21683-2019 “Release of simulated nano-objects from paints, varnishes, and tinted plastics in pigments and fillers determination experiments”

3 Terms and Definitions
For the purposes of this document, the terms and definitions given in ISO/TS 80004-1, ISO/TS 80004-2 and the following articles apply.

3.1 General terms and definitions

3.1.1 Aerosol

A system of solid or liquid particles suspended in a gas

[Source: ISO 15900:2009, 2.1]

3.1.2 nanometer scale

The length ranges from about 1 nm to 100 nm

Note 1: Attributes that are not extrapolated from larger sizes are mainly represented within this length range.

[Source: ISO/TS 80004-1:2015, 2.1]

3.1.3 Nanoparticles

For nanoobjects (3.1.4), all external dimensions are at the nanoscale (3.1.2), where there is no significant difference between the length of the longest axis and the shortest axis of the nanoobject

Note 1: If the size difference is large (usually more than 3x), terms such as nanofibers or nanoplates may be superior to the term nanoparticles.

[Source: ISO/TS 80004-2:2015, 4.4]

3.1.4 Nano objects

Nanoscale discrete materials with one, two or three external dimensions (3.1.2)

Note 1: The second and third outer dimensions are orthogonal to the first dimension and to each other.

[Source: ISO/TS 80004-1:2015, 2.5]

3.1.5 Paint

Tinted coating material that, when applied to the substrate, forms an opaque dry film with protective, decorative or specific technical properties

[Source: ISO 4618:2014, 2.184]

3.1.6 Equivalent spherical diameter x

The diameter of the sphere has the same physical properties as the particle in the measurement

Note 1: For example, the physical properties are the same as the sedimentation rate or the displacement volume or projection area of the electrolyte solution under the microscope.

Note 2: The physical property referred to by equivalent diameter should be denoted by an appropriate subscript, e.g. x S for equivalent surface area diameter or xV for equivalent volume diameter.

[Source: ISO 26824:2013, 1.6]

3.1.7 Particle Size Distribution. PSD

The cumulative distribution of material fractions less than a given particle size (size too small), expressed by the distribution density of material fractions in an equivalent spherical diameter or other linear size or size class divided by the width of that class

Note 1: Particle size distribution is described in ISO 9276-1.

3.1.8 Condensed particle counter

Instrument for measuring aerosol particle Number Concentration (3.1.1)

Note 1: Particle sizes detected are usually less than a few hundred nanometers and larger than a few nanometers.

Note 2: CPC is a possible detector for use with DEMC.

Note 3: In some cases, a condensed particle counter may be called a condensed matter kernel counter (CNC).

[Source: ISO 15900:2009, 2.5]

3.1.9 Differential electromobility Classifier

A classifier that can select aerosol (3.1.1) particles based on electromobility and deliver them to the outlet

Note 1: DEMC classifies aerosol particle sizes by balancing the electrical power on each particle with its aerodynamic drag in the electric field. The classified particles fall within a narrow range of electromobility determined by the operating conditions and physical size of the DEMC, and they can have different sizes due to the amount of charge they have.

[Source: ISO 15900:2009, 2.7]

3.1.10 Differential mobility analysis system DMAS

System for measuring submicron aerosol (3.1.1) particle size distribution, consisting of DEMC, flowmeter, particle detector, interconnect pipe, computer and suitable software

[Source: ISO 15900:2009, 2.8]

3.2 Specific terms and definitions

3.2.1 Particle release in paints, varnishes and plastics

Materials are transferred from paints, varnishes and plastics to liquids or gases due to mechanical stresses

3.2.2 Particle number release n

The total number of particles in a specified size range released from the sample due to mechanical stress

3.2.3 The number of particles in a specific area releases nA

Particle number release (3.2.2), divided by the stressed surface area of the sample

3.2.4 Mass ratio particle number release

Particle number release (3.2.2), divided by the mass of material removed

3.2.5 Total volume flow

Volume flow, which absorbs all air transport emissions at the particle source and transfers them

3.2.6 Particle number concentration nV

Particles per volume of air

3.2.7 Process concentration

Particle number concentration (3.2.6), total volume velocity (3.2.5) and particle number release (3.2.2) due to mechanical stress on the sample

3.2.8 Measuring concentration

The particle number concentration (3.2.6) was calibrated against a specified process concentration dilution (3.2.7) to establish better conditions for aerosol analysis

3.2.9 Concentration of sample room

Particle number concentration (3.2.6), which results from the release of particle number in a specific area under better mixing conditions at specified room heights (3.2.3)

Note 1: Intermodel concentrations are independent of the selected test conditions and represent reference concentrations for actual particle number concentrations (e.g., particle pollution in the laboratory) when heights between models are carefully selected.

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