Plastics -- Aromatic isocyanates for use in the production of polyurethanes -- Determination of total chlorine

ISO 26603:2008 is used to determine the total chlorine content of aromatic isocyanates used in the preparation of polyurethanes. The difference between the total chlorine content and the hydrolyzable chlorine content (see ISO 15028) is a measure of the process solvents left in the product. Both test methods are applicable to a variety of organic compounds, including aliphatic isocyanates, but the amount of sample used might need to be adjusted. These test methods can be used for research or for quality control.

Plastiques -- Isocyanates aromatiques utilisés pour la production de polyuréthannes -- Dosage du chlore total

General Information

Status
Replaced
Publication Date
10-Aug-2008
Withdrawal Date
10-Aug-2008
Current Stage
6060 - International Standard published
Start Date
30-Jul-2008
Completion Date
11-Aug-2008
Ref Project

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ISO 26603:2008 - Plastics -- Aromatic isocyanates for use in the production of polyurethanes -- Determination of total chlorine
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INTERNATIONAL ISO
STANDARD 26603
First edition
2008-08-15
Plastics — Aromatic isocyanates for use
in the production of polyurethanes —
Determination of total chlorine
Plastiques — Isocyanates aromatiques utilisés pour la production de
polyuréthannes — Dosage du chlore total
Reference number
ISO 26603:2008(E)
ISO 2008
---------------------- Page: 1 ----------------------
ISO 26603:2008(E)
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ii © ISO 2008 – All rights reserved
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ISO 26603:2008(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.

International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.

The main task of technical committees is to prepare International Standards. Draft International Standards

adopted by the technical committees are circulated to the member bodies for voting. Publication as an

International Standard requires approval by at least 75 % of the member bodies casting a vote.

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.

ISO 26603 was prepared by Technical Committee ISO/TC 61, Plastics, Subcommittee SC 12, Thermosetting

materials.
© ISO 2008 – All rights reserved iii
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ISO 26603:2008(E)
Introduction

Isocyanates are typically produced by phosgenation of an aromatic amine using chlorine-substituted

benzenes (e.g. o-dichlorobenzene) as reaction solvents. ISO 15028 is used to determine the hydrolyzable

chlorine content of the isocyanates. The test methods in this International Standard are used to determine the

total chlorine content of aromatic isocyanates. The difference between the total chlorine content and the

hydrolyzable chlorine content is a measure of the reaction solvents left in the product, and therefore is a useful

tool for assessing product quality.
iv © ISO 2008 – All rights reserved
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INTERNATIONAL STANDARD ISO 26603:2008(E)
Plastics — Aromatic isocyanates for use in the production of
polyurethanes — Determination of total chlorine

SAFETY PRECAUTIONS — Persons using this International Standard should be familiar with normal

laboratory practice, if applicable. This International Standard does not purport to address all of the

safety concerns, if any, associated with its use. It is the responsibility of the user to establish

appropriate safety and health practices and to ensure compliance with any regulatory requirements.

1 Scope

This International Standard is used to determine the total chlorine content of aromatic isocyanates used in the

preparation of polyurethanes. The difference between the total chlorine content and the hydrolyzable chlorine

content (see ISO 15028) is a measure of the process solvents left in the product. Both test methods are

applicable to a variety of organic compounds, including aliphatic isocyanates, but the amount of sample used

might need to be adjusted. These test methods can be used for research or for quality control.

NOTE This International Standard is technically equivalent to ASTM D 4661-03.
2 Normative references

The following referenced documents are indispensable for the application of this document. For dated

references, only the edition cited applies. For undated references, the latest edition of the referenced

document (including any amendments) applies.
ISO 3696, Water for analytical laboratory use — Specification and test methods

ISO 6353-2, Reagents for chemical analysis — Part 2: Specifications — First series

ISO 6353-3, Reagents for chemical analysis — Part 3: Specifications — Second series

3 Terms and definitions
For the purposes of this document, the following definitions apply.
3.1
isocyanates
organic compounds containing one or more NCO groups
3.2
polyurethane

polymer prepared by the reaction of an organic di- or polyisocyanate with compounds containing two or more

hydroxyl groups
3.3
hydrolyzable chlorine

organic or inorganic chlorine compounds formed in the production of isocyanates that react with methanol

under the conditions of ISO 15028 to liberate hydrogen chloride
© ISO 2008 – All rights reserved 1
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ISO 26603:2008(E)
3.4
total chlorine

inorganic and organically bound chlorine present in isocyanates that is converted to titratable chlorides under

the combustion conditions of the test
4 Principle

In each test method, the organic matter in the sample is destroyed by combustion with oxygen, thus

converting the organically combined chlorine to ionic chloride. The chloride is determined potentiometrically by

titration with silver nitrate (AgNO ) solution.
4.1 Test Method A
Combustion of the sample is done in a pressurized oxygen bomb.
4.2 Test Method B
Combustion is done at atmospheric pressure in a Schöniger oxygen flask.
NOTE For information on the Schöniger flask, refer to Reference [6].
5 Interferences

Thiocyanate, cyanide, sulphide, bromide, iodide or other substances capable of reacting with silver ion, as

well as substances capable of reducing silver ion in acid solution, will interfere with the determination.

6 Sampling

Since organic isocyanates react with atmospheric moisture, take special precautions in sampling. Usual

sampling methods, even when conducted rapidly, can expose the isocyanate to moisture and cause

contamination of the sample with insoluble ureas; therefore, blanket the sample with a dry inert gas (e.g.

nitrogen, argon or dried air) at all times.

WARNING — Organic isocyanates are hazardous when absorbed through the skin, or when the

vapours are breathed.

CAUTION — Provide adequate ventilation and wear protective gloves and eyeglasses.

7 Test Method A ─ Total chlorine by oxygen bomb
7.1 Reagents
7.1.1 Purity of reagents

Reagent-grade chemicals shall be used in all tests. Other grades may be used, provided that it is first

determined that the reagent is of sufficiently high purity to permit its use without lessening the accuracy of the

determination. Unless otherwise indicated, it is intended that all reagents shall conform to the specifications of

ISO 6353-2 and ISO 6353-3.
2 © ISO 2008 – All rights reserved
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ISO 26603:2008(E)
7.1.2 Purity of water

Unless otherwise indicated, references to water shall be understood to mean grade 2 water as defined by

ISO 3696.
7.1.3 Ethyl Alcohol ─ Conforming to ISO 6353-2.

7.1.4 Nitric acid (diluted) ─ While stirring vigorously, add 100 ml of nitric acid (HNO specific gravity 1,42)

to 100 ml of water cooled in an ice bath.
7.1.5 Oxygen ─ Free of combustible materials and halogen compounds.

7.1.6 Silver nitrate, standard solution (0,01 M) ─ Prepare a 0,01 M silver nitrate (AgNO ) solution, and

check frequently enough to detect changes of 0,000 5 M, either gravimetrically or potentiometrically, using

standard hydrochloric acid (HCl).

7.1.7 Sodium carbonate solution (50 g/l) ─ Dissolve 135 g of sodium carbonate decahydrate

(Na CO 10H O) in water and dilute to 1 l.
2 3 2
7.2 Apparatus

7.2.1 Weighing bottle and balance ─ suitable for weighing a liquid sample by difference to the nearest

0,5 mg.

7.2.2 Oxygen bomb apparatus ─ A corrosion-resistant steel reactor capable of being pressurized to 40

atmospheres of pure oxygen, followed by electrical ignition of the sample by use of an internal fuse wire. The

bomb must be capable of withstanding the pressure build-up caused by the combustion of the sample. Parr

Bomb No. 1108 is a suitable device (see Figure 1). Equivalent apparatus may be substituted with appropriate

changes in the procedure.
7.2.3 Fuse wire ─ iron-nickel-chromium, No. 34 B & S gage.

7.2.4 Titrimeter ─ automatic (preferred) or manual, equipped with a silver/silver chloride electrode pair and

a 10 ml capacity microburette.

7.2.5 Bubble counter ─ a 100 ml graduate and delivery tube, or a bent “L” glass tube connected to a piece

of rubber tubing. The graduate is filled to the 50 ml mark with water to which 3 ml of 0,1 M AgNO and 1 drop

of concentrated nitric acid have been added. Any turbidity that develops indicates that HCl gas is being lost

when venting the bomb.
© ISO 2008 – All rights reserved 3
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ISO 26603:2008(E)
Figure 1 — Parr oxygen bomb
7.3 Procedure

7.3.1 Make certain that the bomb, oxygen lines, and fittings are free of oil and grease.

WARNING — Small quantities of either oil or grease may cause a violent explosion.

When the bomb is used repeatedly, a film may form on its inner surface. Remove this film by rotating the

bomb on a lathe at about 300 rpm and polishing the inside surface with Grit No. 2/0 or equivalent paper

coated with light machine oil, then with a paste made from grit-free chromic oxide and water. This procedure

will remove all but very deep pits while polishing the surface. Before using the bomb, wash it with soap and

water to remove residual cutting oil or paste. Bombs with pitted surfaces should not be used because they will

retain chlorine from sample to sample.

7.3.2 Weigh a 0,9 g sample by difference to ± 0,000 5g into the combustion capsule.

WARNING — A severe safety hazard exists if more than 1 g of sample is used.

7.3.3 Fit a 100 mm, iron-nickel fuse wire (7.2.3) onto the two electrodes. Place the combustion capsule on

the loop electrode and adjust the fuse wire in the capsule so that it is under the surface of the sample but does

not touch the capsule. Place about 5 ml of Na CO solution (7.1.7) in the bomb and, with a small rubber

2 3

spatula, wet the interior surface of the bomb, including the head, as thoroughly as possible. Put the bomb

head in the bomb cylinder and the contact ring on top of the bomb head, screwing the cap down finger-tight.

Close the outlet v
...

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