ISO/DIS 24376

Rubber, raw natural - Guidelines for technically specified low-protein natural rubber

Caoutchouc naturel brut -- Lignes directrices pour le caoutchouc naturel à faible teneur en protéines spécifié techniquement

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DRAFT INTERNATIONAL STANDARD
ISO/DIS 24376
ISO/TC 45/SC 3 Secretariat: AFNOR
Voting begins on: Voting terminates on:
2021-04-06 2021-06-29
Rubber, raw natural - Guidelines for technically specified
low-protein natural rubber

Caoutchouc naturel brut — Lignes directrices pour le caoutchouc naturel à faible teneur en protéines

spécifié techniquement
ICS: 83.040.10
THIS DOCUMENT IS A DRAFT CIRCULATED
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ISO/DIS 24376:2021(E)
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PROVIDE SUPPORTING DOCUMENTATION. ISO 2021
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ISO/DIS 24376:2021(E)
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ii © ISO 2021 – All rights reserved
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ISO/DIS 24376:2021(E)
Contents Page

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

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

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

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

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

4 Material composition ....................................................................................................................................................................................... 2

5 Grade structure ...................................................................................................................................................................................................... 2

6 Specification of requirement ................................................................................................................................................................... 2

7 Sampling ........................................................................................................................................................................................................................ 3

8 Packaging ..................................................................................................................................................................................................................... 4

Annex A (informative) Low protein natural rubber (LPNR) ........................................................................................................ 5

Annex B (informative) Examples of the removal of proteins from raw natural rubber ..................................7

Bibliography .............................................................................................................................................................................................................................11

© ISO 2021 – All rights reserved iii
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ISO/DIS 24376:2021(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

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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).

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expressions related to conformity assessment, as well as information about ISO's adherence to the

World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www .iso .org/

iso/ foreword .html.

This document was prepared by Technical Committee ISO/TC 45, Rubber and rubber product,

Subcommittee SC 3, Raw materials (including latex) for use in the rubber industry.

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 2021 – All rights reserved
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ISO/DIS 24376:2021(E)
Introduction

Significant developments have taken place in the supply of raw natural rubber, especially in relation

to the number of different grades that are technically specified. The constant viscosity (CV), latex (L)

and gel content (LoV) grades have been added in addition to the initial grades covered in ISO 2000. The

development and availability of physical and/or chemically modified grades are now reported in the

technical literature (see Annex A).

This document encompasses raw rubber, natural which has been subjected to a process of removal of

naturally occurring proteins that is commonly and commercially referred to as Deproteinised Natural

Rubber (DPNR).

However, the processes employed for removal of the proteins from natural rubber do not completely

do so. The measurement of these residual proteins and specifying limits for these proteins is necessary

to specify these dry rubber grades of low protein rubber. The acronym LPNR would identify and

distinguish these grades from the latex grades and from a completely protein free natural rubber

should it become available (see Annex B).

This document encompasses some rubbers that are better defined elsewhere. For more precise

specifications, reference may need to be made to such specifications in particular cases which may be

found in the standards or in the literature of manufacturers of these low protein natural rubber grades.

© ISO 2021 – All rights reserved v
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DRAFT INTERNATIONAL STANDARD ISO/DIS 24376:2021(E)
Rubber, raw natural - Guidelines for technically specified
low-protein natural rubber
1 Scope

This document provides guidance on the specification of low protein natural rubber (LPNR). A grading

system is proposed, based on the origin of the natural rubber content and differentiated by the two

processes, enzymatic and non enzymatic, applied for removal of the proteins.
2 Normative references

The following documents are referred to in the text in such a way that some or all of their content

constitutes requirements of this document. For dated references, only the edition cited applies. For

undated references, the latest edition of the referenced document (including any amendments) applies.

ISO 247-1, Rubber — Determination of ash — Part 1: Combustion method

ISO 248-1, Rubber, raw — Determination of volatile–matter content — Part 1: Hot-mill method and

oven method
ISO 249, Rubber, raw natural — Determination of dirt content

ISO 289-1, Rubber, unvulcanized — Determinations using a shearing-disc viscometer — Part 1:

Determination of Mooney viscosity

ISO 1656, Rubber, raw natural, and rubber latex, natural — Determination of nitrogen content

ISO 1795, Rubber, raw natural and raw synthetic — Sampling and further preparative procedures

ISO 2007, Rubber, unvulcanized — Determination of plasticity — Rapid-plastimeter method

ISO 2930, Rubber, raw natural — Determination of plasticity retention index (PRI)

ASTM D5712, Standard Test Method for Analysis of Aqueous Extractable Protein in Latex, Natural Rubber,

and Elastomeric Products Using the Modified Lowry Method

ASTM D6499, Standard Test Method for Immunological Measurement of Antigenic Protein in Hevea Natural

Rubber (HNR) and its Products
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 Elec
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