Graphic technology and deinked pulp — Guidance for assessing the deinking performance of printed paper products

This document provides guidance for representatives of the paper value chain for the design of printed paper products, with a view to deinkability contributing to recyclability in support of the circular economy. It describes relevant deinking processes, and the deinking performance of printed paper products produced with different printing, finishing and converting technologies in those deinking processes. It provides a list of relevant quality characteristics of industrial deinked pulps and a list of their possible usages based on those characteristics. This document does not include guidance for paper-based products which are not intended to be deinked.

Technologie graphique et pâte désencrée — Lignes directrices pour l'évaluation de la performance de désencrage des produits en papier imprimé

Le présent document fournit des lignes directrices pour les représentants de la chaîne de valeur du papier concernant la conception de produits en papier imprimé, afin que le désencrage contribue à la recyclabilité et soutienne l'économie circulaire. Il décrit les processus de désencrage pertinents ainsi que les performances de désencrage de produits en papier imprimé fabriqués à l'aide de différentes technologies d'impression, de finition et de transformation au sein de ces processus de désencrage. Il fournit une liste des caractéristiques de qualité pertinentes des pâtes désencrées industrielles et une liste des utilisations possibles en fonction de ces caractéristiques. Le présent document n'inclut pas de lignes directrices pour les produits à base de papier qui ne sont pas destinés à être désencrés.

General Information

Status
Published
Publication Date
01-Dec-2020
Current Stage
6060 - International Standard published
Completion Date
02-Dec-2020
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TECHNICAL ISO/TS
SPECIFICATION 21331
First edition
2020-11
Graphic technology and deinked
pulp — Guidance for assessing the
deinking performance of printed
paper products
Technologie graphique et pâte désencrée — Lignes directrices
pour l'évaluation de la performance de désencrage des produits en
papier imprimé
Reference number
ISO/TS 21331:2020(E)
ISO 2020
---------------------- Page: 1 ----------------------
ISO/TS 21331:2020(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2020

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 2020 – All rights reserved
---------------------- Page: 2 ----------------------
ISO/TS 21331:2020(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

Introduction ..................................................................................................................................................................................................................................v

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 1

3.1 Terms related to material .............................................................................................................................................................. 1

3.2 Terms relating to paper recycling and deinking ........................................................................................................ 2

3.3 Terms relating to quality requirements ............................................................................................................................ 2

4 How deinkability contributes to recyclability in support of the circular economy ........................3

4.1 What is circular economy? The importance of recyclability ........................................................................... 3

4.2 Specific recommendations for printing ............................................................................................................................. 4

4.3 Specifics recommendations for converting .................................................................................................................... 5

5 Relevant deinking processes ................................................................................................................................................................... 5

5.1 General ........................................................................................................................................................................................................... 5

5.2 Pulping ........................................................................................................................................................................................................... 6

5.3 Flotation ........................................................................................................................................................................................................ 6

5.4 Washing ......................................................................................................................................................................................................... 6

5.5 Dispersing ................................................................................................................................................................................................... 6

5.6 Bleaching ...................................................................................................................................................................................................... 7

6 Deinking performance ................................................................................................................................................................................... 7

6.1 Principles for assessment of deinking performance of printed products ........................................... 7

6.2 General experience .............................................................................................................................................................................. 7

7 Quality characteristics of industrial deinked pulps ........................................................................................................ 9

7.1 General ........................................................................................................................................................................................................... 9

7.2 Pulp Brightness ...................................................................................................................................................................................... 9

7.3 Pulp Colour ................................................................................................................................................................................................. 9

7.4 Dirt Particles ............................................................................................................................................................................................. 9

8 Possible usages of industrial deinked pulps (based on Clause 7 characteristics) ........................10

9 Reporting ...................................................................................................................................................................................................................11

Annex A Deinking methods .......................................................................................................................................................................................12

Bibliography .............................................................................................................................................................................................................................15

© ISO 2020 – All rights reserved iii
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ISO/TS 21331:2020(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 documents 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).

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of

any patent rights identified during the development of the document will be in the Introduction and/or

on the ISO list of patent declarations received (see www .iso .org/ patents).

Any trade name used in this document is information given for the convenience of users and does not

constitute an endorsement.

For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and

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 6, Paper, board and pulps, and ISO/TC 130,

Graphic Technology.

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 © ISO 2020 – All rights reserved
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ISO/TS 21331:2020(E)
Introduction

Printed graphic paper products play a key role in society. They are conveyers of information through

newspapers and magazines and of culture through books. They therefore contribute to promote

democratic debate and culture but also education and social inclusion.

Paper products are good examples for the circular economy since they are recycled after use already

to a high extent, higher than any other post-consumer material. The recycling of paper products is

beneficial because it allows the fibre to be used several times. However, a good balance between virgin

and recycled fibres is necessary to compensate for losses of material within the paper loop and to avoid

any forest depletion.

Within the paper value chain there are two main material loops – graphic products and packaging

products. Optimum circularity is given if graphic paper products can be kept within the graphic loop.

This document describes the common recycling processes for graphic paper for recycling and addresses

the influencing factors from the product design. Further influencing factors – which are out of this

document’s scope – are collection and handling of used paper products.

Common recycling processes for graphic paper for recycling include deinking, the removal of ink

from the pulp. The majority of paper for recycling that are deinked originates from households and is

therefore a blend of various print products made with different printing and finishing technologies as

well as a variety of paper types. The common deinking processes therefore have to be capable to treat

this blend of paper products for producing quality pulp in an ecological and economical way.

This document mainly addresses stakeholders in the value chain of printing in order to make them

aware about the life of their products after intended use and how they can contribute to the functioning

of the cycle.
© ISO 2020 – All rights reserved v
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TECHNICAL SPECIFICATION ISO/TS 21331:2020(E)
Graphic technology and deinked pulp — Guidance for
assessing the deinking performance of printed paper
products
1 Scope

This document provides guidance for representatives of the paper value chain for the design of printed

paper products, with a view to deinkability contributing to recyclability in support of the circular

economy.

It describes relevant deinking processes, and the deinking performance of printed paper products

produced with different printing, finishing and converting technologies in those deinking processes.

It provides a list of relevant quality characteristics of industrial deinked pulps and a list of their possible

usages based on those characteristics.

This document does not include guidance for paper-based products which are not intended to be

deinked.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
3.1 Terms related to material
3.1.1
recycled paper
paper incorporating fibres obtained from paper recovered after use
[SOURCE: ISO 5127, 3.3.5.2.10]
3.1.2
pulp

fibrous material, generally of vegetable origin, made ready for use in further manufacturing processes

[SOURCE: ISO 4046-2, 2.46]
3.1.3
deinked pulp
DIP

pulp (3.1.2) made from paper and board for recycling from which inks and other contaminants have

been removed
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ISO/TS 21331:2020(E)
3.1.4
printing ink
substance containing pigment(s) and/or dye(s), and carrier fluid(s)

Note 1 to entry: most inks contain additional functional components, such as resins(s), surfactants, stabilizers,

etc., which can impact the deinkability and recyclability of the printed paper.
[SOURCE: ISO 16759, 3.6.3]
3.1.5
substrate

material, such as paper or board, onto which inks, coatings and varnishes are printed or laid down

3.2 Terms relating to paper recycling and deinking
3.2.1
recycling

process of converting used paper products, returns or residuals of finishing and converting operations

into new paper or board
3.2.2
deinking
process of ink removal from pulp (3.1.2) during the recycling (3.2.1) process
3.3 Terms relating to quality requirements
3.3.1
dirt

any non-fibrous particle visible on a sheet in marked contrast or colour to the rest of the sheet

[SOURCE: ISO 4046-2 2.24 modified]
3.3.2
Fluorescent Whitening Agents
FWA

chemical compounds that absorb light in the UV and violet regions of the electromagnetic spectrum

and reemit at different wavelength in the visible spectrum

Note 1 to entry: Fluorescent Whitening Agents are also sometimes referred to as Optical Brightening Agents (OBA).

3.3.3
2 2

dirt (3.3.1) particle area, expressed in mm /m , for particles with a size of at least 50 μm circle

equivalent diameter and accordingly an area of at least 0,002 0 mm
3.3.4
250
2 2

dirt (3.3.1) particle area, expressed in mm /m , for particles with a size of at least 250 μm circle

equivalent diameter and accordingly an area of at least 0,049 1 mm
3.3.5
CIELAB colour space and CIELAB values

three-dimensional, approximately uniform colour space, produced by plotting, in rectangular

coordinates L*, a*, b*

Note 1 to entry: The quantity L* is a measure of the lightness, where L* = 0 corresponds to black and L* = 100

corresponds to the perfect reflecting diffuser. Visually, the quantities a* and b* represent respectively the red-

green and yellow-blue axes in colour space, such that:
— +a* is a measure of the degree of redness;
2 © ISO 2020 – All rights reserved
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ISO/TS 21331:2020(E)
— −a* is a measure of the degree of greenness;
— +b* is a measure of the degree of yellowness;
— −b* is a measure of the degree of blueness.
If both a* and b* are equal to zero, the test piece is grey.
[SOURCE: ISO 5631-2, 3.6 modified, ISO 15397, 3.17]
3.3.6
brightness (ISO Brightness and D 65 Brightness)
R457

intrinsic diffuse radiance [reflectance] factor measured with a reflectometer having the characteristics

described in ISO 2469, equipped with a filter or corresponding function having an effective wavelength

of 457 nm and a half bandwidth of 44 nm, and adjusted so that the UV content of the irradiation

incident upon the test piece corresponds to that of the CIE illuminant C/2° according to ISO 2470-1

(ISO Brightness, indoor conditions) or that of the CIE illuminant D65/10° according to ISO 2470-2 (D 65

Brightness, outdoor conditions)

Note 1 to entry: Brightness is subject to the intrinsic radiance reflectance factor as measured with a reflectometer

and subject to the illumination source.
3.3.7
fibre yield

ratio of the oven-dry mass of organic material after flotation to the oven-dry mass of organic material

before flotation

Note 1 to entry: Organic material is the total material, reduced by the oven-dry mass of its ash.

Note 2 to entry: The organic material mainly consists of cellulosic fibers and fines.

[SOURCE: ISO 21993:2020, 3.5]
3.3.8
ash content

ratio of the mass of the residue remaining after a test specimen of paper, board, pulp or cellulose

nanomaterial is ignited at (525 ± 25) °C to the oven-dry mass of the test specimen before ignition

Note 1 to entry: This property has been referred to as either “residue on ignition” or “ash content”.

[SOURCE: ISO 1762, 3.1]

4 How deinkability contributes to recyclability in support of the circular economy

4.1 What is circular economy? The importance of recyclability

The concept of the circular economy comes from the idea that waste, once adequately treated, can

become a resource again, thereby forming a loop in the production-consumption chain. The concept

of the circular economy is rooted in the observation of physical phenomena and natural cycles.

A summary of circular economy is given in Reference [13] inspired from "nothing is lost, nothing is

created, everything is transformed", a quote from Lavoisier.

Value of product, materials and resources is maintained in the economy as long as possible and

generation of waste is minimized.
© ISO 2020 – All rights reserved 3
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ISO/TS 21331:2020(E)

The contribution of circular economy to sustainable development is environmental, economic, and

[14] [15]
social . The following seven issues have been identified:

— Sustainable procurement: aimed at reducing the impact of the raw materials supply or replacing

non-renewable raw materials by renewable ones (resources/procurement management, logistic

management).

— Ecodesign: aimed at taking environmental impacts into account throughout a product life cycle and

integrating them from the very first design stages, (e.g. creation of biodegradable supermarket bags

for businesses; manufacturing of machines which are easily repairable and, at the end of their life

cycle, recyclable or with a reduced environmental impact) (life cycle cost/analysis, environmental

information, sustainable use of raw materials).

— Industrial symbiosis: establishing a method of industrial organization characterized by an improved

management of stocks and flows of materials, energy and services within the same geographic

area (environmental management, interaction between organizations, economic valorisation of

territories).

— Economy of functionality: focusing on usage rather than ownership; selling services rather than

goods (use of products, substitution good services, life extension of products).

— Sustainable consumption: collaborative/participative consumption, purchase/use goods and

services, enlarged responsibility of consumers.
— Life use extension: reuse, repair, reuse of second hands products.

— Material management and end-of-life of product: waste, recycling, characterization, management,

treatment, etc.

In the field of paper, the life cycle of a paper product is composed of a series of value-adding steps, from

the extraction of material resources until the end of the paper product’s life.
Detailed information is given in [14] and [16].
4.2 Specific recommendations for printing
a) Minimize the need to downcycle the paper.
b) Order paper with near net size.

c) Recycle trims/scraps and sort them by homogeneous grades to optimize recycling.

d) Adjust the number of copies to real needs. The required quantities should determine the choice of

printing technology, not the opposite.
e) Adjust the paper’s grammage to the product’s objective.

f) Choose printing processes and materials that can be removed efficiently. Gravure printing and

huge majority of offset prints are known as easily deinkable in industry. Other printing techniques

need evaluation and the deinkability of these prints do depend of the raw materials used and

equipments/facilities in the deinking and recycling operations.

g) Use ink with good deinkability performance which will allow recycling in graphic papers or tissue

paper industry.

h) Use elements for binding that can be easily removed from paper pulp or if not, then without

detrimental impact on pulp quality and waste water treatment.
i) Use inks with low migration for packaging and graphic paper.
j) Minimize the use of UV inks and UV varnishes.
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ISO/TS 21331:2020(E)
4.3 Specifics recommendations for converting
a) Order paper with near net size.
[17]

b) Recycle mis- and overprints and sort them by homogeneous grades to optimize recycling .

c) Adjust paper and board weight or thickness with the packaging objectives.
d) Minimize adding non-paper material.
e) Added material should be easily separated from paper.

f) Use adhesives that can be easily removed from paper pulp or if not, then without detrimental

impact on pulp quality and waste water treatment.
5 Relevant deinking processes
5.1 General

An industrial deinking process is regarded as relevant if it is widely used and documented.

The effectiveness of the deinking process depends on a number of factors, the most significant of which

is whether the material to be recycled can be pre-sorted prior to deinking. One of the goals of the sorting

process is to remove materials which may interfere with the recovery and fibre yield of clean cellulose

fibres. However, pre-sorting constraints may discourage overall recycling of the broader waste stream

by end consumers and in many parts of the world “zero sort” recycling is the norm. This is one reason

why deinking processes need to be adapted or modified to reflect the composition of the local and/or

regional recycling content.
Deinking is a three-step functional process. The steps are as follows:
— Detachment of inks from repulped substrate;
— Fragmentization of the particles into a suitable size range;
— Remove of pigment particles (predominantly by flotation) from the pulp slurry.

NOTE 1 In practice, a deinking plant is more complex, since it also deals with materials other than pigment-

based inks which have to be removed or modified (screening of adhesives and decolouration of dyes).

NOTE 2 Industrial processes can be reproduced in pilot plants.

Production of printed paper products may intentionally add other components, besides ink and toner,

such as cover foils, staples, varnishes and adhesives. To impede the deinking process as little as possible,

the following characteristics are important:
i) Ink and toner particles should be removable.

ii) Other non-paper product components should be large enough and mechanically stable such that

they survive as large particles without being broken down under process conditions into very small

parts, and allow mechanical separation by means of punched screens, slot screens, and centrifugal

cleaners.

iii) Materials applied in very small dimensions or disintegrated into very small parts are less desirable

because they need to be removed by additional technologies e.g. washing which a) uses more water,

and b) will also remove fines, fillers, starches, and other small particles along with toner etc.

NOTE 3 Particularly fines and fillers are substances which are intended to remain in the pulp in most cases.

Components in paper for recycling, which dissolve or become colloidal under standard deinking

conditions (e.g., pH 7 - 10), and reach the process water, pose a risk of unintended spreading to all parts

of papermaking processes or paper fibres. It is recommended that printed paper products contain as

© ISO 2020 – All rights reserved 5
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ISO/TS 21331:2020(E)

few components as possible that dissolve or disperse in weakly alkaline media and form sticky residues

or cause undesirable colour staining.
5.2 Pulping

Pulping is always the first technological step in a paper recycling process. In a big vat pulper, equipped

with a rotor, or in a rotating drum pulper, paper for recycling is mixed with water, chemicals and

agitated, thus losing its structure and disintegrating into individual fibres.

During pulping, the printing ink film should detach from the paper surface – fibres or coating – and

fragment into a size range suitable for separation in subsequent processes. The adhesion of printing ink

to paper depends mainly on ink chemistry and on the drying and/or curing mechanism of the chosen

printing process and additionally on paper properties such as surface structure, fibre type, filler

contents, and so on.

Other additional factors can also impact detachments and fragmentation of ink particles such as aging

of prints.
5.3 Flotation

Flotation, common to most deinking processes worldwide, is used to remove printing ink components

from the pulp. Supported by surface-active substances, printing ink particles gather on the surface of

air bubbles. This process works optimally with hydrophobic printing ink particles sized between 10

and 150 μm. Thus, the ink-loaded air-bubbles stream upwards through the pulp slurry.

At the surface of the pulp slurry, dark foam containing printing inks, fragments of paper fibres, fillers,

and paper-coating pigments segregates. Particles smaller or bigger than the optimum particle size

range are floated with lower efficiency.

In some case water-based printing inks are used (e.g. flexographic newspaper printing). These particles

are hydrophilic, partially adsorbed on fibres and much too small for flotation. These inks may contain

binders soluble in the alkaline range. Consequently, in deinking such inks break up into particles

smaller than one micron in size. These particles are hydrophilic, partially adsorbed and much too small

for flotation. The non-adsorbed inks can be partially removed by washing of the pulp. See 5.4.

Printing ink particles too large for the flotation process occur in cases of tenacious, crosslinked ink

films in thick layers on paper. For example, this could be paper with UV inks. If such coarse printing

ink particles are obtained, the paper mill needs a disperser for comminuting them and subjecting them

to the flotation process. Since this second deinking loop has to treat the complete pulp, it makes the

process more complex and expands the environmental footprint because it requires more energy, and

decreases the fibre yield. One of the reasons is a higher security towards print products which are

difficult to deink in a one-loop plant. Particularly if the quality requirements of the end product are

high, even a two-loop plant cannot produce a high-quality pulp from raw material containing too many

print products which are difficult to deink.
5.4 Washing

Wash deinking is a separation by particle size, retaining large particles, predominantly fibres, on a wire

and washing small particles through the mesh. This process can remove small ink particles, but also

mineral fillers and fines from the pulp. The low fibre yield of wash deinking is prohibitive for most

operations. Therefore, deinking by washing is commonly used for the production of hygiene/tissue

papers and market DIP where, for quality reasons, most of the minerals have to be removed.

5.5 Dispersing

Dispersing is a high-speed kneading of heated pulp. It does not belong to the key processes of deinking

and is not a necessary process step if quality requirements for the deinked pulp are low and if all

processed print products are easily de-inkable. Since this is not the case in most plants, operating

dispersing stages became common. The shear forces in the disperser detach inks which hadn’t been

6 © ISO 2020 – All rights reserved
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ISO/TS 21331:2020(E)

detached in the pulper and fragmentise those which were too large for efficient flotation. Deinking

processes with dispersing need additional dewatering and thickening stages as well as heating. In

order to remove the newly detached and fragmentised ink particles, dispersing shall be followed by an

additional flotation stage.
5.6 Bleaching

Bleaching is common for the production of higher quality grades where it is necessary to achieve higher

brightness from a given raw material. Equipment for either oxidative and/or reductive bleaching is not

the same. Bleaching is an optional step not found in all deinking plants.
6 Deinking performance
6.1 Principles for assessment of deinking performance of printed products

To support the circular economy, print products should be capable of being recycled and deinked to

produce a paper on a similar quality level as their substrate.

When a print product is produced, its fate after its use cannot be predicted normally. In nearly all

cases, industrial deinking operations use a blend of various printed products and the deinked pulp

quality normally does not allow an allocation to an individual print product. Therefore, the deinkability

assessment shall be done by laboratory or pilot plant tests. Laboratory tests are usually simplifie

...

SPÉCIFICATION ISO/TS
TECHNIQUE 21331
Première édition
2020-11
Technologie graphique et pâte
désencrée — Lignes directrices pour
l'évaluation de la performance de
désencrage des produits en papier
imprimé
Graphic technology and deinked pulp — Guidance for assessing the
deinking performance of printed paper products
Numéro de référence
ISO/TS 21331:2020(F)
ISO 2020
---------------------- Page: 1 ----------------------
ISO/TS 21331:2020(F)
DOCUMENT PROTÉGÉ PAR COPYRIGHT
© ISO 2020

Tous droits réservés. Sauf prescription différente ou nécessité dans le contexte de sa mise en œuvre, aucune partie de cette

publication ne peut être reproduite ni utilisée sous quelque forme que ce soit et par aucun procédé, électronique ou mécanique,

y compris la photocopie, ou la diffusion sur l’internet ou sur un intranet, sans autorisation écrite préalable. Une autorisation peut

être demandée à l’ISO à l’adresse ci-après ou au comité membre de l’ISO dans le pays du demandeur.

ISO copyright office
Case postale 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Genève
Tél.: +41 22 749 01 11
E-mail: copyright@iso.org
Web: www.iso.org
Publié en Suisse
ii © ISO 2020 – Tous droits réservés
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ISO/TS 21331:2020(F)
Sommaire Page

Avant-propos ..............................................................................................................................................................................................................................iv

Introduction ..................................................................................................................................................................................................................................v

1 Domaine d’application ................................................................................................................................................................................... 1

2 Références normatives ................................................................................................................................................................................... 1

3 Termes et définitions ....................................................................................................................................................................................... 1

3.1 Termes relatifs au matériau ......................................................................................................................................................... 1

3.2 Termes relatifs au recyclage et au désencrage du papier .................................................................................. 2

3.3 Termes relatifs aux exigences de qualité .......................................................................................................................... 2

4 Comment la désencrabilité participe à la recyclabilité pour soutenir l’économie

circulaire ....................................................................................................................................................................................................................... 4

4.1 Qu’est-ce que l’économie circulaire ? L’importance de la recyclabilité .................................................. 4

4.2 Recommandations spécifiques pour l’impression ................................................................................................... 4

4.3 Recommandations spécifiques pour la transformation ...................................................................................... 5

5 Processus de désencrage pertinents ............................................................................................................................................... 5

5.1 Généralités .................................................................................................................................................................................................. 5

5.2 Mise en pâte ............................................................................................................................................................................................... 6

5.3 Flottation ...................................................................................................................................................................................................... 6

5.4 Lavage ............................................................................................................................................................................................................. 7

5.5 Dispersion ................................................................................................................................................................................................... 7

5.6 Blanchiment .............................................................................................................................................................................................. 7

6 Performances de désencrage .................................................................................................................................................................. 8

6.1 Principes pour l’évaluation des performances de désencrage des produits imprimés ........... 8

6.2 Expérience générale ........................................................................................................................................................................... 8

7 Caractéristiques relatives à la qualité des pâtes désencrées industrielles ..........................................10

7.1 Généralités ...............................................................................................................................................................................................10

7.2 Degré de blancheur de la pâte ................................................................................................................................................10

7.3 Couleur de la pâte ..............................................................................................................................................................................10

7.4 Particules d’impureté .....................................................................................................................................................................11

8 Usages possibles des pâtes désencrées industrielles (selon les caractéristiques

énoncées à l’Article 7)...................................................................................................................................................................................11

9 Rapport........................................................................................................................................................................................................................12

Annexe A Méthodes de désencrage...................................................................................................................................................................14

Bibliographie ...........................................................................................................................................................................................................................17

© ISO 2020 – Tous droits réservés iii
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ISO/TS 21331:2020(F)
Avant-propos

L’ISO (Organisation internationale de normalisation) est une fédération mondiale d’organismes

nationaux de normalisation (comités membres de l’ISO). L’élaboration des Normes internationales est

en général confiée aux comités techniques de l’ISO. Chaque comité membre intéressé par une étude

a le droit de faire partie du comité technique créé à cet effet. Les organisations internationales,

gouvernementales et non gouvernementales, en liaison avec l’ISO participent également aux travaux.

L’ISO collabore étroitement avec la Commission électrotechnique internationale (IEC) en ce qui

concerne la normalisation électrotechnique.

Les procédures utilisées pour élaborer le présent document et celles destinées à sa mise à jour sont

décrites dans les Directives ISO/IEC, Partie 1. Il convient, en particulier de prendre note des différents

critères d’approbation requis pour les différents types de documents ISO. Le présent document a été

rédigé conformément aux règles de rédaction données dans les Directives ISO/IEC, Partie 2 (voir www

.iso .org/ directives).

L’attention est attirée sur le fait que certains des éléments du présent document peuvent faire l’objet de

droits de propriété intellectuelle ou de droits analogues. L’ISO ne saurait être tenue pour responsable

de ne pas avoir identifié de tels droits de propriété et averti de leur existence. Les détails concernant

les références aux droits de propriété intellectuelle ou autres droits analogues identifiés lors de

l’élaboration du document sont indiqués dans l’Introduction et/ou dans la liste des déclarations de

brevets reçues par l’ISO (voir www .iso .org/ patents).

Les appellations commerciales éventuellement mentionnées dans le présent document sont données

pour information, par souci de commodité, à l’intention des utilisateurs et ne sauraient constituer un

engagement.

Pour une explication de la nature volontaire des normes, la signification des termes et expressions

spécifiques de l’ISO liés à l’évaluation de la conformité, ou pour toute information au sujet de l’adhésion

de l’ISO aux principes de l’Organisation mondiale du commerce (OMC) concernant les obstacles

techniques au commerce (OTC), voir le lien suivant : www .iso .org/ iso/ foreword .html.

Le présent document a été élaboré par les comités techniques ISO/TC 6, Papiers, cartons et pâtes, et

ISO/TC 130, Technologie graphique.

Il convient que l’utilisateur adresse tout retour d’information ou toute question concernant le présent

document à l’organisme national de normalisation de son pays. Une liste exhaustive desdits organismes

se trouve à l’adresse www .iso .org/ members .html.
iv © ISO 2020 – Tous droits réservés
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ISO/TS 21331:2020(F)
Introduction

Les produits en papier graphique imprimé jouent un rôle essentiel dans la société. Ils sont porteurs

d’informations grâce aux journaux et aux magazines et passeurs de culture grâce aux livres. Ils

contribuent ainsi à promouvoir le débat démocratique et la culture mais aussi l’éducation et l’intégration

sociale.

Les produits en papier sont de bons exemples du principe de l’économie circulaire car ils sont recyclés

après usage, et ce déjà à grande échelle, à une échelle plus grande que pour tout autre matériau de

post-consommation. Le recyclage des produits en papier est bénéfique car il permet aux fibres d’être

utilisées plusieurs fois. Trouver un bon équilibre entre les fibres vierges et les fibres recyclées est

toutefois nécessaire afin de compenser les pertes en matériaux dans la boucle du papier et d’éviter la

déforestation.

Au sein de la chaîne de valeur du papier, il existe deux boucles de matériaux principales : une pour

les produits graphiques et une pour les produits d’emballage. Une circularité optimale est atteinte

lorsque les produits en papier graphique peuvent être conservés dans la boucle graphique. Le présent

document décrit les processus de recyclage courants pour le papier graphique à recycler et traite des

facteurs d’influence dès la conception du produit. La collecte et la manipulation des produits en papier

usagés sont d’autres facteurs d’influence, mais ils ne relèvent pas du domaine d’application du présent

document.

Les processus de recyclage courants du papier graphique à recycler incluent le désencrage, à savoir

l’élimination de l’encre de la pâte. La majorité du papier à recycler qui est désencré provient des

ménages ; elle est donc composée d’un mélange de divers produits imprimés fabriqués grâce à

différentes technologies d’impression et de finition et sur différents types de papier. Les processus

courants de désencrage doivent donc être en mesure de traiter ce mélange de produits en papier afin de

produire une pâte de qualité, et ce de façon écologique et économique.

Le présent document s’adresse principalement aux parties prenantes dans la chaîne de valeur du

secteur de l’impression afin de les sensibiliser sur le cycle de vie de leurs produits après utilisation

prévue et sur la façon dont ils peuvent contribuer au fonctionnement de ce cycle.

© ISO 2020 – Tous droits réservés v
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SPÉCIFICATION TECHNIQUE ISO/TS 21331:2020(F)
Technologie graphique et pâte désencrée — Lignes
directrices pour l'évaluation de la performance de
désencrage des produits en papier imprimé
1 Domaine d’application

Le présent document fournit des lignes directrices pour les représentants de la chaîne de valeur du

papier concernant la conception de produits en papier imprimé, afin que le désencrage contribue à la

recyclabilité et soutienne l’économie circulaire.

Il décrit les processus de désencrage pertinents ainsi que les performances de désencrage de produits

en papier imprimé fabriqués à l’aide de différentes technologies d’impression, de finition et de

transformation au sein de ces processus de désencrage.

Il fournit une liste des caractéristiques de qualité pertinentes des pâtes désencrées industrielles et une

liste des utilisations possibles en fonction de ces caractéristiques.

Le présent document n’inclut pas de lignes directrices pour les produits à base de papier qui ne sont pas

destinés à être désencrés.
2 Références normatives
Le présent document ne contient aucune référence normative.
3 Termes et définitions

Pour les besoins du présent document, les termes et définitions suivants s’appliquent.

L’ISO et l’IEC tiennent à jour des bases de données terminologiques destinées à être utilisées en

normalisation, consultables aux adresses suivantes :

— ISO Online browsing platform : disponible à l’adresse https:// www .iso .org/ obp

— IEC Electropedia : disponible à l’adresse http:// www .electropedia .org/
3.1 Termes relatifs au matériau
3.1.1
papier recyclé

papier incorporant des fibres obtenues à partir de papier récupéré après utilisation

[SOURCE: : ISO 5127, 3.3.5.2.10]
3.1.2
pâte

matière fibreuse, le plus souvent d’origine végétale, préparée en vue de subir d’autres traitements de

fabrication
[SOURCE: : ISO 4046-2, 2.46]
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ISO/TS 21331:2020(F)
3.1.3
pâte désencrée
DIP

pâte (3.1.2) fabriquée à partir de papier et de carton à recycler, dont les encres et autres contaminants

ont été éliminés
3.1.4
encre d’impression

substance contenant un ou plusieurs pigment(s) et/ou colorant(s) et fluide(s) porteur(s)

Note 1 à l'article: la plupart des encres contiennent des composants fonctionnels additionnels, comme des

résines, des agents tensioactifs, des stabilisants, etc. qui peuvent avoir une influence sur la désencrabilité et la

recyclabilité du papier imprimé.
[SOURCE: : ISO 16759, 3.6.3]
3.1.5
substrat

matériau, tel que le papier ou le carton, sur lequel les encres, les couches et les vernis sont imprimés

ou apposés
3.2 Termes relatifs au recyclage et au désencrage du papier
3.2.1
recyclage

processus de transformation des produits en papier usagé, des chutes ou des résidus d’opérations de

finition et de transformation pour créer du papier ou du carton neuf
3.2.2
désencrage

processus consistant à éliminer l’encre de la pâte (3.1.2) pendant le processus de recyclage (3.2.1)

3.3 Termes relatifs aux exigences de qualité
3.3.1
impureté

toute particule non fibreuse visible sur une feuille, et ayant un aspect ou une teinte contrastant avec le

reste de la feuille
[SOURCE: : ISO 4046-2 2.24 modifiée]
3.3.2
agents de blanchiment fluorescents
FWA

composés chimiques absorbant la lumière dans les gammes ultraviolette et violette du spectre

électromagnétique et les réémettant selon différentes longueurs d’onde dans le spectre visible

Note 1 à l'article: à l’article : Les agents de blanchiment fluorescents sont parfois également appelés « agents

d’azurage optique » (OBA).
3.3.3
2 2

surface des particules d’impureté (3.3.1), exprimée en mm /m , pour les particules mesurant au

moins 50 μm de diamètre équivalent circulaire, c’est-à-dire une surface d’au moins 0,002 0 mm

3.3.4
250
2 2

surface des particules d’impureté (3.3.1), exprimée en mm /m , pour les particules mesurant au

moins 250 μm de diamètre équivalent circulaire, c’est-à-dire une surface d’au moins 0,049 1 mm

2 © ISO 2020 – Tous droits réservés
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ISO/TS 21331:2020(F)
3.3.5
espace chromatique CIELAB et valeurs CIELAB

espace chromatique à trois dimensions approximativement uniforme, obtenu en portant en coordonnées

rectangulaires les grandeurs L*, a*, b*

Note 1 à l'article: La grandeur L* est une mesure de la clarté de l’éprouvette, où L* = 0 correspond au noir et L* = 100

est définie comme étant le diffuseur parfait par réflexion. Visuellement, les grandeurs a* et b*représentent

respectivement les axes rouge-vert et jaune-bleu de l’espace chromatique, de sorte que :

— +a* est une mesure de la composante rouge de l’éprouvette ;
— −a* est une mesure de la composante verte de l’éprouvette ;
— +b* est une mesure de la composante jaune de l’éprouvette ;
— −b* est une mesure de la composante bleue de l’éprouvette.
Si a* et b* sont toutes les deux égales à zéro, l’éprouvette est grise.
[SOURCE: : ISO 5631-2, 3.6 modifiée, ISO 15397, 3.17]
3.3.6
degré de blancheur (degré de blancheur ISO et degré de blancheur D 65)
R457

facteur de luminance diffuse (réflectance) intrinsèque, mesuré avec un réflectomètre présentant les

caractéristiques décrites dans l’ISO 2469, équipé d’un filtre ou doté d’une fonction correspondante,

ayant une longueur d’onde efficace de 457 nm et une largeur de bande à mi-hauteur de 44 nm, et réglé

de manière que la teneur en UV du rayonnement incident arrivant sur l’éprouvette corresponde à celle

de l’illuminant CIE C avec un observateur à 2° selon l’ISO 2470-1 (degré de blancheur ISO, conditions

d’éclairage intérieur) ou à celle de l’illuminant CIE D65 avec un observateur à 10° selon l’ISO 2470-2

(degré de blancheur D 65, conditions de lumière extérieure)

Note 1 à l'article: Le degré de blancheur est soumis au facteur de luminance (réflectance) intrinsèque tel que

mesuré à l’aide d’un réflectomètre et soumis à la source d’éclairage.
3.3.7
rendement en fibres

rapport de la masse anhydre de matière organique après flottation à la masse anhydre de matière

organique avant flottation

Note 1 à l'article: La matière organique correspond à la matière totale après soustraction de la masse anhydre de

ses cendres.

Note 2 à l'article: à l’article : La matière organique est principalement constituée de fibres et de fines cellulosiques.

[SOURCE: : ISO 21993:2020, 3.5]
3.3.8
teneur en cendres

rapport de la masse du résidu restant après incinération d’une éprouvette de papier, carton, pâte ou

nanomatériau à base de cellulose à (525 ± 25) °C à la masse anhydre de l’éprouvette avant incinération

Note 1 à l'article: Cette propriété était dénommée « résidu après incinération » ou « teneur en cendres » dans de

précédentes éditions du présent document.
[SOURCE: : ISO 1762, 3.1]
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ISO/TS 21331:2020(F)
4 Comment la désencrabilité participe à la recyclabilité pour soutenir
l’économie circulaire
4.1 Qu’est-ce que l’économie circulaire ? L’importance de la recyclabilité

Le principe d’économie circulaire repose sur l’idée que les déchets, une fois correctement traités,

peuvent de nouveau constituer une ressource, pour ainsi créer une boucle dans la chaîne production-

consommation. La notion d’économie circulaire trouve son origine dans l’observation des phénomènes

physiques et des cycles naturels. La Référence [13] donne un résumé du concept de l’économie circulaire,

inspiré par la citation de Lavoisier : « Rien ne se perd, rien ne se crée, tout se transforme ».

La valeur des produits, matériaux et ressources est maintenue aussi longtemps que possible au sein de

l’économie et la génération de déchets est réduite au minimum.

La contribution de l’économie circulaire au développement durable est environnementale, économique

[14] [15]
et sociale . Les sept piliers suivants ont été identifiés :

— l’approvisionnement durable : vise à réduire l’impact de l’approvisionnement en matières premières

ou à remplacer les matières premières non renouvelables par des matières premières renouvelables

(gestion des ressources/de l’approvisionnement, gestion de la chaîne logistique) ;

— l’écoconception : vise à prendre en compte les impacts environnementaux à travers l’ensemble du

cycle de vie d’un produit et à les intégrer dès les toutes premières étapes de la conception (par

exemple : création de sacs de supermarché biodégradables pour les entreprises, fabrication de

machines facilement réparables et recyclables ou présentant un impact environnemental réduit à la

fin de leur cycle de vie) (coût/analyse du cycle de vie, informations environnementales, utilisation

durable des matières premières) ;

— la symbiose industrielle : vise à établir une méthode d’organisation industrielle caractérisée par une

gestion optimisée des stocks et des flux de matériaux, d’énergie et de services au sein de la même

zone géographique (gestion environnementale, interaction entre les organisations, valorisation

économique des territoires) ;

— l’économie de la fonctionnalité : se concentre sur l’usage plutôt que sur la propriété, la vente de

services plutôt que de biens (utilisation des produits, services de substitution de biens, allongement

de la durée de vie des produits) ;

— la consommation durable : tend vers la consommation collaborative/participative, achat versus

utilisation de biens et services, responsabilité élargie des consommateurs ;

— l’allongement de la durée d’usage : encourage à réutiliser, réparer, réutiliser des produits de

seconde main ;

— la gestion des matériaux et fin de vie des produits : se concentre sur les déchets, le recyclage, la

caractérisation, la gestion, le traitement, etc.

Dans le secteur du papier, le cycle de vie des produits en papier est constitué d’une série d’étapes à valeur

ajoutée, de l’extraction des ressources matérielles jusqu’à la fin du cycle de vie des produits en papier.

Des informations détaillées sont données en [14] et [16].
4.2 Recommandations spécifiques pour l’impression
a) Réduire au minimum le besoin de décycler le papier.
b) Commander du papier au format proche des dimensions nettes.

c) Recycler les rognures et les chutes et les trier par sortes de papier homogènes pour optimiser le

recyclage.
4 © ISO 2020 – Tous droits réservés
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ISO/TS 21331:2020(F)

d) Adapter le nombre de copies aux besoins réels. Il convient que les quantités requises déterminent le

choix de la technologie d’impression, et non l’inverse.
e) Ajuster le grammage du papier aux objectifs du produit.

f) Choisir des processus et matériaux d’impression permettant un désencrage efficace. L’héliogravure

et la grande majorité des imprimés offset sont connus dans le secteur industriel pour être facilement

désencrables. D’autres techniques d’impression nécessitent d’être évaluées et la désencrabilité de

ces imprimés dépend des matières premières employées ainsi que des installations/équipements

utilisés dans les opérations de désencrage et de recyclage.

g) Utiliser de l’encre présentant de bonnes performances en matière de désencrabilité, ceci permettant

ensuite le recyclage dans le secteur des papiers graphiques ou papiers tissue.

h) Utiliser des éléments de reliure pouvant être facilement éliminés de la pâte de papier ou, si cela

n’est pas possible, sans impact néfaste sur la qualité de la pâte et le traitement des eaux usées.

i) Utiliser des encres à faible migration pour les papiers d’emballage et graphiques.

j) Réduire au minimum l’utilisation des encres et vernis UV.
4.3 Recommandations spécifiques pour la transformation
a) Commander du papier au format proche des dimensions nettes.

b) Recycler les imprimés ratés ou superflus et les trier par sortes de papier homogènes pour optimiser

[17]
le recyclage .

c) Adapter la masse ou l’épaisseur du papier ou du carton aux objectifs d’emballage.

d) Réduire au minimum l’ajout de matériaux autres que du papier.

e) Il convient que les matériaux ajoutés puissent facilement être séparés du papier.

f) Utiliser des adhésifs facilement éliminables de la pâte de papier ou, si cela n’est pas possible, sans

impact néfaste sur la qualité de la pâte et le traitement des eaux usées.
5 Processus de désencrage pertinents
5.1 Généralités

Un processus de désencrage industriel est considéré comme pertinent s’il est largement utilisé et

documenté.

L’efficacité du processus de désencrage dépend d’un certain nombre de facteurs, le plus important

d’entre eux étant la possibilité d’un tri préalable du matériau à recycler avant le désencrage. L’un des

objectifs du processus de tri est de retirer les matériaux susceptibles d’interférer avec la récupération

de fibres en cellulose propres et le rendement en fibres. Cependant, les contraintes liées au tri préalable

peuvent décourager les consommateurs finaux de procéder au recyclage général de flux de déchets plus

importants et, dans de nombreuses régions du monde, le « recyclage sans tri » est la norme. C’est l’une

des raisons pour lesquelles les processus de désencrage ont besoin d’être adaptés ou modifiés pour

refléter la composition des contenus à recycler au niveau local et/ou régional.

Le désencrage est un processus opérationnel en trois étapes. Les étapes sont les suivantes :

— séparation des encres du substrat remis en pâte ;
— fragmentation des particules pour obtenir une plage de tailles appropriée ;

— élimination des particules de pigment (principalement par flottation) à partir de la pâte défibrée.

© ISO 2020 – Tous droits réservés 5
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ISO/TS 21331:2020(F)

NOTE 1 En pratique, une usine de désencrage est plus complexe car elle traite également d’autres matériaux

que les encres à base de pigments, qui doivent être éliminés ou modifiés (passage au tamis pour éliminer les

adhésifs, décoloration des colorants).

NOTE 2 Les processus industriels peuvent être reproduits dans des usines pilotes.

Les fabricants de produits en papier imprimé peuvent ajouter intentionnellement d’autres composants,

outre l’encre et le toner, comme des films de couverture, des agrafes, des vernis, des adhésifs. Afin

d’entraver au minimum le processus de désencrage, les caractéristiques suivantes sont importantes :

i) Il convient que les particules d’encre et de toner soient éliminables.

ii) Il convient que les autres composants du produit non fabriqués en papier soient de dimensions

suffisamment grandes et mécaniquement stables de sorte à demeurer sous forme de grosses

particules sans être réduits en très petits morceaux dans les conditions du processus, et que leur

séparation mécanique à l’aide de tamis perforés, de tamis à fentes et d’épurateurs centrifuges soit

possible.

iii) Les matériaux appliqués en très petites dimensions ou désintégrés en très petits morceaux sont

moins souhaitables car leur élimination nécessite l’emploi de technologies supplémentaires (par

exemple, une opération de lavage qui a) consomme plus d’eau et b) retirera également les fines,

matières de charge, amidons et autres particules de petite taille avec le toner, etc.).

NOTE 3 Les fines et matières de charge, notamment, sont des substances destinées à rester dans la pâte dans

la plupart des cas.

Les composants présents dans le papier à recycler, qui se dissolvent ou deviennent colloïdaux dans des

conditions de désencrage standard (par exemple, pH 7 - 10), et rejoignent l’eau du traitement, présentent

un risque de diffusion involontaire à toutes les étapes du processus de fabrication du papier ou à toutes

les fibres du papier. Il est recommandé que les produits en papier imprimé contiennent le moins possible

de composants qui se dissolvent ou se dispersent dans un milieu faiblement alcalin, formant des résidus

collants, ou qui provoquent une coloration indésirable.
5.2 Mise en pâte

La mise en pâte constitue toujours la première étape technologique du processus de recyclage du

papier. Dans un pulpeur à cuve doté d’un rotor ou un pulpeur à tambour rotatif de grandes dimensions,

le papier à recycler est mélangé à de l’eau et à des produits chimiques. Le mélange est agité jusqu’à ce

que sa structure soit désintégrée en fibres individuelles.

Lors de la mise en pâte, il convient que le film d’encre d’impression se détache de la surface du

papier (fibres ou couche) et se fragmente en morceaux d’une taille appropriée pour la séparation

lors des processus suivants. L’adhérence de l’encre d’impression au papier dépend principalement

de la composition chimique de l’encre et du mécanisme de séchage/polymérisation du processus

d’impression choisi. Elle dépend également des propriétés du papier, comme la structure superficielle,

le type de fibres, la teneur en matière de charge, etc.

D’autres facteurs peuvent aussi influer sur la séparation et la fragmentation des particules d’encre,

comme le vieillissement des imprimés.
5.3 Flottation

La flottation, une pratique commune à la plupart des processus de désencrage dans le monde, est

utilisée pour éliminer les composants de l’encre d’impression de la p
...

TECHNICAL ISO/TS
SPECIFICATION 21331
First edition
Graphic technology and deinked
pulp — Guidance for assessing the
deinking performance of printed
paper products
Technologie graphique et pâte désencrée — Lignes directrices pour
l'évaluation de la performance de désencrage des produits en papier
imprimé
PROOF/ÉPREUVE
Reference number
ISO/TS 21331:2020(E)
ISO 2020
---------------------- Page: 1 ----------------------
ISO/TS 21331:2020(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2020

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 PROOF/ÉPREUVE © ISO 2020 – All rights reserved
---------------------- Page: 2 ----------------------
ISO/TS 21331:2020(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

Introduction ..................................................................................................................................................................................................................................v

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 1

3.1 Terms related to material .............................................................................................................................................................. 1

3.2 Terms relating to paper recycling and deinking ........................................................................................................ 2

3.3 Terms relating to quality requirements ............................................................................................................................ 2

4 How deinkability contributes to recyclability in support of the circular economy ........................3

4.1 What is circular economy? The importance of recyclability ........................................................................... 3

4.2 Specific recommendations for printing ............................................................................................................................. 4

4.3 Specifics recommendations for converting .................................................................................................................... 5

5 Relevant deinking processes ................................................................................................................................................................... 5

5.1 General ........................................................................................................................................................................................................... 5

5.2 Pulping ........................................................................................................................................................................................................... 6

5.3 Flotation ........................................................................................................................................................................................................ 6

5.4 Washing ......................................................................................................................................................................................................... 6

5.5 Dispersing ................................................................................................................................................................................................... 6

5.6 Bleaching ...................................................................................................................................................................................................... 7

6 Deinking performance ................................................................................................................................................................................... 7

6.1 Principles for assessment of deinking performance of printed products ........................................... 7

6.2 General experience .............................................................................................................................................................................. 7

7 Quality characteristics of industrial deinked pulps ........................................................................................................ 9

7.1 General ........................................................................................................................................................................................................... 9

7.2 Pulp Brightness ...................................................................................................................................................................................... 9

7.3 Pulp Colour ................................................................................................................................................................................................. 9

7.4 Dirt Particles ............................................................................................................................................................................................. 9

8 Possible usages of industrial deinked pulps (based on Clause 7 characteristics) ........................10

9 Reporting ...................................................................................................................................................................................................................11

Annex A Deinking methods .......................................................................................................................................................................................12

Bibliography .............................................................................................................................................................................................................................15

© ISO 2020 – All rights reserved PROOF/ÉPREUVE iii
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ISO/TS 21331:2020(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.

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iso/ foreword .html.

This document was prepared by Technical Committee ISO/TC 6, Paper, board and pulps, and ISO/TC 130,

Graphic Technology.

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complete listing of these bodies can be found at www .iso .org/ members .html.
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ISO/TS 21331:2020(E)
Introduction

Printed graphic paper products play a key role in society. They are conveyers of information through

newspapers and magazines and of culture through books. They therefore contribute to promote

democratic debate and culture but also education and social inclusion.

Paper products are good examples for the circular economy since they are recycled after use already

to a high extent, higher than any other post-consumer material. The recycling of paper products is

beneficial because it allows the fibre to be used several times. However, a good balance between virgin

and recycled fibres is necessary to compensate for losses of material within the paper loop and to avoid

any forest depletion.

Within the paper value chain there are two main material loops – graphic products and packaging

products. Optimum circularity is given if graphic paper products can be kept within the graphic loop.

This document describes the common recycling processes for graphic paper for recycling and addresses

the influencing factors from the product design. Further influencing factors – which are out of this

document’s scope – are collection and handling of used paper products.

Common recycling processes for graphic paper for recycling include deinking, the removal of ink

from the pulp. The majority of paper for recycling that are deinked originates from households and is

therefore a blend of various print products made with different printing and finishing technologies as

well as a variety of paper types. The common deinking processes therefore have to be capable to treat

this blend of paper products for producing quality pulp in an ecological and economical way.

This document mainly addresses stakeholders in the value chain of printing in order to make them

aware about the life of their products after intended use and how they can contribute to the functioning

of the cycle.
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TECHNICAL SPECIFICATION ISO/TS 21331:2020(E)
Graphic technology and deinked pulp — Guidance for
assessing the deinking performance of printed paper
products
1 Scope

This document provides guidance for representatives of the paper value chain for the design of printed

paper products, with a view to deinkability contributing to recyclability in support of the circular

economy.

It describes relevant deinking processes, and the deinking performance of printed paper products

produced with different printing, finishing and converting technologies in those deinking processes.

It provides a list of relevant quality characteristics of industrial deinked pulps and a list of their possible

usages based on those characteristics.

This document does not include guidance for paper-based products which are not intended to be

deinked.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
3.1 Terms related to material
3.1.1
recycled paper
paper incorporating fibres obtained from paper recovered after use
[SOURCE: ISO 5127, 3.3.5.2.10]
3.1.2
pulp

fibrous material, generally of vegetable origin, made ready for use in further manufacturing processes

[SOURCE: ISO 4046-2, 2.46]
3.1.3
deinked pulp
DIP

pulp (3.1.2) made from paper and board for recycling from which inks and other contaminants have

been removed
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ISO/TS 21331:2020(E)
3.1.4
printing ink
substance containing pigment(s) and/or dye(s), and carrier fluid(s)

Note 1 to entry: most inks contain additional functional components, such as resins(s), surfactants, stabilizers,

etc., which can impact the deinkability and recyclability of the printed paper.
[SOURCE: ISO 16759, 3.6.3]
3.1.5
substrate

material, such as paper or board, onto which inks, coatings and varnishes are printed or laid down

3.2 Terms relating to paper recycling and deinking
3.2.1
recycling

process of converting used paper products, returns or residuals of finishing and converting operations

into new paper or board
3.2.2
deinking
process of ink removal from pulp (3.1.2) during the recycling (3.2.1) process
3.3 Terms relating to quality requirements
3.3.1
dirt

any non-fibrous particle visible on a sheet in marked contrast or colour to the rest of the sheet

[SOURCE: ISO 4046-2 2.24 modified]
3.3.2
Fluorescent Whitening Agents
FWA

chemical compounds that absorb light in the UV and violet regions of the electromagnetic spectrum

and reemit at different wavelength in the visible spectrum

Note 1 to entry: Fluorescent Whitening Agents are also sometimes referred to as Optical Brightening Agents (OBA).

3.3.3
2 2

dirt (3.3.1) particle area, expressed in mm /m , for particles with a size of at least 50 μm circle

equivalent diameter and accordingly an area of at least 0,002 0 mm
3.3.4
250
2 2

dirt (3.3.1) particle area, expressed in mm /m , for particles with a size of at least 250 μm circle

equivalent diameter and accordingly an area of at least 0,049 1 mm
3.3.5
CIELAB colour space and CIELAB values

three-dimensional, approximately uniform colour space, produced by plotting, in rectangular

coordinates L*, a*, b*

Note 1 to entry: The quantity L* is a measure of the lightness, where L* = 0 corresponds to black and L* = 100

corresponds to the perfect reflecting diffuser. Visually, the quantities a* and b* represent respectively the red-

green and yellow-blue axes in colour space, such that:
— +a* is a measure of the degree of redness;
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ISO/TS 21331:2020(E)
— −a* is a measure of the degree of greenness;
— +b* is a measure of the degree of yellowness;
— −b* is a measure of the degree of blueness.
If both a* and b* are equal to zero, the test piece is grey.
[SOURCE: ISO 5631-2, 3.6 modified, ISO 15397, 3.17]
3.3.6
brightness (ISO Brightness and D 65 Brightness)
R457

intrinsic diffuse radiance [reflectance] factor measured with a reflectometer having the characteristics

described in ISO 2469, equipped with a filter or corresponding function having an effective wavelength

of 457 nm and a half bandwidth of 44 nm, and adjusted so that the UV content of the irradiation

incident upon the test piece corresponds to that of the CIE illuminant C/2° according to ISO 2470-1

(ISO Brightness, indoor conditions) or that of the CIE illuminant D65/10° according to ISO 2470-2 (D 65

Brightness, outdoor conditions)

Note 1 to entry: Brightness is subject to the intrinsic radiance reflectance factor as measured with a reflectometer

and subject to the illumination source.
3.3.7
fibre yield

ratio of the oven-dry mass of organic material after flotation to the oven-dry mass of organic material

before flotation

Note 1 to entry: Organic material is the total material, reduced by the oven-dry mass of its ash.

Note 2 to entry: The organic material mainly consists of cellulosic fibers and fines.

[SOURCE: ISO 21993:2020, 3.5]
3.3.8
ash content

ratio of the mass of the residue remaining after a test specimen of paper, board, pulp or cellulose

nanomaterial is ignited at 525 °C ± 25 °C to the oven-dry mass of the test specimen before ignition

Note 1 to entry: This property has been referred to as either “residue on ignition” or “ash content”.

[SOURCE: ISO 1762, 3.1]

4 How deinkability contributes to recyclability in support of the circular economy

4.1 What is circular economy? The importance of recyclability

The concept of the circular economy comes from the idea that waste, once adequately treated, can

become a resource again, thereby forming a loop in the production-consumption chain. The concept

of the circular economy is rooted in the observation of physical phenomena and natural cycles.

A summary of circular economy is given in Reference [13] inspired from "nothing is lost, nothing is

created, everything is transformed", a quote from Lavoisier.

Value of product, materials and resources is maintained in the economy as long as possible and

generation of waste is minimized.
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The contribution of circular economy to sustainable development is environmental, economic, and

[14] [15]
social . The following seven issues have been identified:

— Sustainable procurement: aimed at reducing the impact of the raw materials supply or replacing

non-renewable raw materials by renewable ones (resources/procurement management, logistic

management).

— Ecodesign: aimed at taking environmental impacts into account throughout a product life cycle and

integrating them from the very first design stages, (e.g. creation of biodegradable supermarket bags

for businesses; manufacturing of machines which are easily repairable and, at the end of their life

cycle, recyclable or with a reduced environmental impact (life cycle cost/analysis, environmental

information, sustainable use of raw materials).

— Industrial symbiosis: establishing a method of industrial organization characterized by an improved

management of stocks and flows of materials, energy and services within the same geographic

area (environmental management, interaction between organizations, economic valorisation of

territories).

— Economy of functionality: focusing on usage rather than ownership; selling services rather than

goods (use of products, substitution good services, life extension of products).

— Sustainable consumption: collaborative/participative consumption, purchase/use goods and

services, enlarged responsibility of consumers.
— Life use extension: reuse, repair, reuse of second hands products.

— Management materials and end-of-life of product: waste, recycling, characterization, management,

treatment, etc.

In the field of paper, the life cycle of a paper product is composed of a series of value-adding steps, from

the extraction of material resources until the end of the paper product’s life.
Detailed information is given in [14] and [16].
4.2 Specific recommendations for printing
a) Minimize the need to downcycle the paper.
b) Order paper with near net size.

c) Recycle trims/scraps and sort them by homogeneous grades to optimize recycling.

d) Adjust the number of copies to real needs. The required quantities should determine the choice of

printing technology, not the opposite.
e) Adjust the paper’s grammage to the product’s objective.

f) Choose printing processes and materials that can be removed efficiently. Gravure printing and

huge majority of offset prints are known as easily deinkable in industry. Other printing techniques

need evaluation and the deinkability of these prints do depend of the raw materials used and

equipments/facilities in the deinking and recycling operations.

g) Use ink with good deinkability performance which will allow recycling in graphic papers or tissue

paper industry.

h) Use elements for binding that can be easily removed from paper pulp or if not, then without

detrimental impact on pulp quality and waste water treatment.
i) Use inks with low migration for packaging and graphic paper.
j) Minimize the use of UV inks and UV varnishes.
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4.3 Specifics recommendations for converting
a) Order paper with near net size.
[17]

b) Recycle mis- and overprints and sort them by homogeneous grades to optimize recycling .

c) Adjust paper and board weight or thickness with the packaging objectives.
d) Minimize adding non-paper material.
e) Added material should be easily separated from paper.

f) Use adhesives that can be easily removed from paper pulp or if not, then without detrimental

impact on pulp quality and waste water treatment.
5 Relevant deinking processes
5.1 General

An industrial deinking process is regarded as relevant if it is widely used and documented.

The effectiveness of the deinking process depends on a number of factors, the most significant of which

is whether the material to be recycled can be pre-sorted prior to deinking. One of the goals of the sorting

process is to remove materials which may interfere with the recovery and fibre yield of clean cellulose

fibres. However, pre-sorting constraints may discourage overall recycling of the broader waste stream

by end consumers and in many parts of the world “zero sort” recycling is the norm. This is one reason

why deinking processes need to be adapted or modified to reflect the composition of the local and/or

regional recycling content.
Deinking is a three-step functional process. The steps are as follows:
— Detachment of inks from repulped substrate;
— Fragmentization of the particles into a suitable size range;
— Remove of pigment particles (predominantly by flotation) from the pulp slurry.

NOTE 1 In practice, a deinking plant is more complex, since it also deals with materials other than pigment-

based inks which have to be removed or modified, as well as screening of adhesives and decolouration of dyes.

NOTE 2 Industrial processes can be reproduced in pilot plants.

Production of printed paper products may intentionally add other components, besides ink and toner,

such as cover foils, staples, varnishes and adhesives. To impede the deinking process as little as possible,

the following characteristics are important:
i) Ink and toner particles should be removable.

ii) Other non-paper product components should be large enough and mechanically stable such that

they survive as large particles without being broken down under process conditions into very small

parts, and allow mechanical separation by means of punched screens, slot screens, and centrifugal

cleaners.

iii) Materials applied in very small dimensions or disintegrated into very small parts are less desirable

because they need to be removed by additional technologies e.g. washing which a) uses more water,

and b) will also remove fines, fillers, starches, and other small particles along with toner etc.

NOTE 3 Particularly fines and fillers are substances which are intended to remain in the pulp in most cases.

Components in paper for recycling, which dissolve or become colloidal under standard deinking

conditions (e.g., pH 7 - 10), and reach the process water, pose a risk of unintended spreading to all parts

of papermaking processes or paper fibres. It is recommended that printed paper products contain as

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few components as possible that dissolve or disperse in weakly alkaline media and form sticky residues

or cause undesirable colour staining.
5.2 Pulping

Pulping is always the first technological step in a paper recycling process. In a big vat pulper, equipped

with a rotor, or in a rotating drum pulper, paper for recycling is mixed with water, chemicals and

agitated, thus losing its structure and disintegrating into individual fibres.

During pulping, the printing ink film should detach from the paper surface – fibres or coating – and

fragment into a size range suitable for separation in subsequent processes. The adhesion of printing ink

to paper depends mainly on ink chemistry and on the drying and/or curing mechanism of the chosen

printing process and additionally on paper properties such as surface structure, fibre type, filler

contents, and so on.

Other additional factors can also impact detachments and fragmentation of ink particles such as aging

of prints.
5.3 Flotation

Flotation, common to most deinking processes worldwide, is used to remove printing ink components

from the pulp. Supported by surface-active substances, printing ink particles gather on the surface of

air bubbles. This process works optimally with hydrophobic printing ink particles sized between 10

and 150 μm. Thus, the ink-loaded air-bubbles stream upwards through the pulp slurry.

At the surface of the pulp slurry, dark foam containing printing inks, fragments of paper fibres, fillers,

and paper-coating pigments segregates. Particles smaller or bigger than the optimum particle size

range are floated with lower efficiency.

In some case water-based printing inks are used (e.g. flexographic newspaper printing). These particles

are hydrophilic, partially adsorbed on fibres and much too small for flotation. These inks may contain

binders soluble in the alkaline range. Consequently, in deinking such inks break up into particles

smaller than one micron in size. These particles are hydrophilic, partially adsorbed and much too small

for flotation. The non-adsorbed inks can be partially removed by washing of the pulp. See 5.4.

Printing ink particles too large for the flotation process occur in cases of tenacious, crosslinked ink

films in thick layers on paper. For example, this could be paper with UV inks. If such coarse printing

ink particles are obtained, the paper mill needs a disperser for comminuting them and subjecting them

to the flotation process. Since this second deinking loop has to treat the complete pulp, it makes the

process more complex and expands the environmental footprint because it requires more energy, and

decreases the fibre yield. One of the reasons is a higher security towards print products which are

difficult to deink in a one-loop plant. Particularly if the quality requirements of the end product are

high, even a two-loop plant cannot produce a high-quality pulp from raw material containing too many

print products which are difficult to deink.
5.4 Washing

Wash deinking is a separation by particle size, retaining large particles, predominantly fibres, on a wire

and washing small particles through the mesh. This process can remove small ink particles, but also

mineral fillers and fines from the pulp. The low fibre yield of wash deinking is prohibitive for most

operations. Therefore, deinking by washing is commonly used for the production of hygiene/tissue

papers and market DIP where, for quality reasons, most of the minerals have to be removed.

5.5 Dispersing

Dispersing is a high-speed kneading of heated pulp. It does not belong to the key processes of deinking

and is not a necessary process step if quality requirements for the deinked pulp are low and if all

processed print products are easily de-inkable. Since this is not the case in most plants, operating

dispersing stages became common. The shear forces in the disperser detach inks which hadn’t been

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detached in the pulper and fragmentise those which were too large for efficient flotation. Deinking

processes with dispersing need additional dewatering and thickening stages as well as heating. In

order to remove the newly detached and fragmentised ink particles, dispersing shall be followed by an

additional flotation stage.
5.6 Bleaching

Bleaching is common for the production of higher quality grades where it is necessary to achieve higher

brightness from a given raw material. Equipment for either oxidative and/or reductive bleaching is not

the same. Bleaching is an optional step not found in all deinking plants.
6 Deinking performance
6.1 Principles for assessment of deinking performance of printed products

To support the circular economy, print products should be capable of being recycled and deinked to

produce a paper on a similar quality level as their substrate.

When a print product is produced, its fate after its use cannot be predicted normally. In nearly all

cases, industrial deinking operations use a blend of various printed products and the deinked pulp

quality normally does not allow an allocation to an individ
...

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