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

This document provides guidelines and gives requirements 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.

Caoutchouc naturel brut — Lignes directrices et exigences pour le caoutchouc naturel à faible teneur en protéines spécifié techniquement

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Published
Publication Date
24-Mar-2022
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5020 - FDIS ballot initiated: 2 months. Proof sent to secretariat
Start Date
21-Dec-2021
Completion Date
21-Dec-2021
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INTERNATIONAL ISO
STANDARD 24376
First edition
2022-03
Rubber, raw natural — Guidelines and
requirements for technically specified
low-protein natural rubber
Caoutchouc naturel brut — Lignes directrices et exigences
pour le caoutchouc naturel à faible teneur en protéines spécifié
techniquement
Reference number
ISO 24376:2022(E)
© ISO 2022
---------------------- Page: 1 ----------------------
ISO 24376:2022(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2022

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
© ISO 2022 – All rights reserved
---------------------- Page: 2 ----------------------
ISO 24376:2022(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

iii
© ISO 2022 – All rights reserved
---------------------- Page: 3 ----------------------
ISO 24376:2022(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 45, Rubber and rubber products,

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.
© ISO 2022 – All rights reserved
---------------------- Page: 4 ----------------------
ISO 24376:2022(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 rubber (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 natural rubber, 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 are not complete.

The measurement of these residual proteins and specifying limits for these proteins is necessary to

specify these dry rubber grades of low protein rubber. Low protein natural rubber (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 2022 – All rights reserved
---------------------- Page: 5 ----------------------
INTERNATIONAL STANDARD ISO 24376:2022(E)
Rubber, raw natural — Guidelines and requirements for
technically specified low-protein natural rubber
1 Scope

This document provides guidelines and gives requirements 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 terminology databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
low protein natural rubber
LPNR

natural rubber obtained by a deproteinisation process from the latex of Hevea brasiliensis and typically

processed into block rubber, and having properties complying with the criteria for the grade concerned

© ISO 2022 – All rights reserved
---------------------- Page: 6 ----------------------
ISO 24376:2022(E)
3.2
constant viscosity rubber
natural rubber who
...

FINAL
INTERNATIONAL ISO/FDIS
DRAFT
STANDARD 24376
ISO/TC 45/SC 3
Rubber, raw natural — Guidelines and
Secretariat: AFNOR
requirements for technically specified
Voting begins on:
2021-12-21 low-protein natural rubber
Voting terminates on:
Caoutchouc naturel brut — Lignes directrices et exigences
2022-02-15
pour le caoutchouc naturel à faible teneur en protéines spécifié
techniquement
RECIPIENTS OF THIS DRAFT ARE INVITED TO
SUBMIT, WITH THEIR COMMENTS, NOTIFICATION
OF ANY RELEVANT PATENT RIGHTS OF WHICH
THEY ARE AWARE AND TO PROVIDE SUPPOR TING
DOCUMENTATION.
IN ADDITION TO THEIR EVALUATION AS
Reference number
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO-
ISO/FDIS 24376:2021(E)
LOGICAL, COMMERCIAL AND USER PURPOSES,
DRAFT INTERNATIONAL STANDARDS MAY ON
OCCASION HAVE TO BE CONSIDERED IN THE
LIGHT OF THEIR POTENTIAL TO BECOME STAN-
DARDS TO WHICH REFERENCE MAY BE MADE IN
NATIONAL REGULATIONS. © ISO 2021
---------------------- Page: 1 ----------------------
ISO/FDIS 24376:2021(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2021

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
© ISO 2021 – All rights reserved
---------------------- Page: 2 ----------------------
ISO/FDIS 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

iii
© ISO 2021 – All rights reserved
---------------------- Page: 3 ----------------------
ISO/FDIS 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

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 45, Rubber and rubber products,

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.
© ISO 2021 – All rights reserved
---------------------- Page: 4 ----------------------
ISO/FDIS 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 rubber (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 natural rubber, 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 are not complete.

The measurement of these residual proteins and specifying limits for these proteins is necessary to

specify these dry rubber grades of low protein rubber. Low protein natural rubber (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
---------------------- Page: 5 ----------------------
FINAL DRAFT INTERNATIONAL STANDARD ISO/FDIS 24376:2021(E)
Rubber, raw natural — Guidelines and requirements for
technically specified low-protein natural rubber
1 Scope

This document provides guidelines and gives requirements 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 terminology databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
low protein natural rubber
LPNR

natural rubber obtained by a deproteinisation process from the latex of Hevea brasiliensis and typically

pro
...

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