ASTM D4663 - 20

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Designation: D4663 −20
Standard Test Method for
Polyurethane Raw Materials: Determination of Hydrolyzable
Chlorine of Isocyanates
1
This standard is issued under the ﬁxed designation D4663; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope*
1.1 This test method determines the hydrolyzable chlorine
content of toluene-2,4-diisocyanate, toluene-2,6-diisocyanate,
or mixtures of the two. It is acceptable to apply this test method
to other isocyanates of suitable solubility. (See Note 1.) The
main sources of hydrolyzable chlorine in the isocyanates are
carbamoyl chloride and dissolved phosgene. Both of these
compounds react with alcohols and water, forming ureas,
carbamates, carbon dioxide, and hydrochloric acid. (See Note
2.)
1.2 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro-
priate safety, health, and environmental practices and deter-
mine the applicability of regulatory limitations prior to use.
NOTE 1—It is possible that this test method is applicable to crude
polymeric isocyanates. However, the precision with crude polymeric
isocyanates has not been established.
NOTE 2—This standard is identical to ISO 15028.
1.3 This international standard was developed in accor-
dance with internationally recognized principles on standard-
ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom-
mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee.
2. Referenced Document
2.1 ASTM Standards:
2
D883 Terminology Relating to Plastics
D1193 Speciﬁcation for Reagent Water
E456 Terminology Relating to Quality and Statistics
E2935 Practice for Conducting Equivalence Testing in
Laboratory Applications
2.2 ISO Standards:
ISO 15028 Plastics—Aromatic Isocyanates for Use in the
Production of Polyurethanes—Determination of Hydroly-
sable Chlorine
3
3. Terminology
3.1 Deﬁnitions—Terms used in this standard are deﬁned in
accordance with Terminology D883, unless otherwise speci-
ﬁed. For terms relating to precision and bias and associated
issues, the terms used in this standard are deﬁned in accordance
with Terminology E456.
3.2 Deﬁnitions of Terms Speciﬁc to This Standard:
3.2.1 hydrolyzable chloride—the low-level chlorine-
containing components of the isocyanate, such as carbamoyl
chlorides, which react with water or alcohol to form HCl.
4. Summary of Test Method
4.1 The hydrolyzable chlorine reacts with methanol, liber-
ating hydrochloric acid. The titratable chlorides are then
determined potentiometrically using a standard silver nitrate
solution.
5. Signiﬁcance and Use
5.1 This test method can be used for research or for quality
control to characterize toluene diisocyanates. Hydrolyzable
chlorine correlates with performance in some polyurethane
systems.
6. Interferences
6.1 Thiocyanate, cyanide, sulﬁde, bromide, iodide, or other
substances capable of reacting with silver ions, as well as
substances capable of reducing silver ions in acid solution, will
interfere with the determination.
7. Apparatus
7.1 Weighing Bottle, or any device capable of weighing a
liquid by difference to the nearest 0.1 g.
1
This test method is under the jurisdiction of ASTM Committee D20 on Plastics
and is the direct responsibility of Subcommittee D20.22 on Cellular Materials -
Plastics and Elastomers.
Current edition approved April 1, 2020. Published April 2020. Originally
approved in 1987. Last previous edition approved in 2015 as D4663 - 15. DOI:
10.1520/D4663-20.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website.
3
Available from American National Standards Institute (ANSI), 25 W. 43rd St.,
4th Floor, New York, NY 10036, http://www.ansi.org.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

7.2 Hot Plate, with magnetic stirrer.

7.3 Potentiometric Titrator, or pH meter.

7.4 Combination Silver Billet Electrode.

8. Reagents and Materials

8.1 Purity of Reagents—Use reagent grade chemicals in all

tests. Unless otherwise indicated, it is intended that all reagents

conform to the speciﬁcations of the Committee on Analytical

Reagents of the American Chemical Society where such

speciﬁcations are available.

Other grades may be used, pro-

vided it is ﬁrst ascertained that the reagent is of sufficiently

high purity to permit its use without lessening the accuracy of

the determination.

8.2 Purity of Water—Unless otherwise indicated, references

to water shall be understood to mean reagent water as deﬁned

by Type I of Speciﬁcation D1193.

8.3 Concentrated Nitric Acid (HNO

sp gr 1.42).

8.4 Methanol.

8.5 Silver Nitrate Standard Solution (0.01 N)—Standardize

with standard hydrochloric acid, either gravimetrically or

potentiometrically, frequently enough to detect changes of

0.0005 N.

9. Sampling

9.1 Since organic isocyanates react with atmospheric

moisture, take special precautions in sampling. Usual sampling

methods, even when conducted rapidly, can cause contamina-

tion of the sample with insoluble urea. Therefore, blanket the

sample with dry air or nitrogen at all times. (Warning—

Diisocyanates are eye, skin and respiratory irritants at concen-

trations above the occupational exposure limit (TLV or PEL).

Diisocyanates can cause skin and respiratory sensitization

(asthma) in some people. Once sensitized, it is essential to limit

further exposure to diisocyanates. Use a combination of

engineering controls and personal protective equipment, in-

cluding respiratory, skin and eye protection, to prevent over-

exposure to diisocyanates. Consult the product suppliers’

Safety Data Sheet (SDS) for more detailed information about

potential health effects and other speciﬁc safety and handling

instructions for the product.)

10. Test Conditions

10.1 Since isocyanates react with moisture, keep laboratory

humidity low, preferably around 50 % relative humidity. See

Section 9of this standard for guidance on how to keep

moisture out of the sample.

11. Procedure

11.1 Weigh (by difference to the nearest 0.1 g) 9 to 11 g of

sample from a sampling weighing bottle into a clean, dry

400-mL beaker (Note 3). Add 50 mL of methanol and stir. Stir

continuously while the reaction starts at which point the beaker

will become warm and crystals may form on the sides of the

beaker (Note 4). Fill the beaker half-full with water (Note 5)

and boil gently for 30 min.

NOTE 3—If the hydrolyzable chlorine content is expected to be less than

0.01 %, use 18 to 22 g of sample.

NOTE 4—Some isocyanates will not react readily, and slight warming

may be necessary to initiate reaction. Other isocyanates may react, as

indicated by warming of reactants, but may not form crystals.

NOTE 5—Add the water quickly to keep the reactants from solidifying

and to minimize the loss of HCl.

11.2 Wash the sides of the beaker with water and remove

and wash the stirring bar. Cool the beaker in an ice bath to

about 10°C and add 10 drops of HNO

. Titrate potentiometri-

cally with 0.01 NAgNO

solution using a combination silver

billet electrode. If the chloride content is greater than 0.2 %,

use 0.1 Ninstead of 0.01 NAgNO

solution.

12. Calculation

12.1 Calculate the hydrolyzable chlorine as weight percent

as follows:

Hydrolyzable chlorine, % 535. 45 3A3N3100/

1000 3W

53.545 3A3N/W

where:

A= AgNO

solution required for titration of the sample,

mL,

N= normality of the AgNO

solution, meq/mL,

W= sample used, g, and

3.545 = constant combining the atomic weight of chlorine

(35.45 mg/meq), the conversion from milligrams to

grams (1000), and conversion to percent (100).

13. Precision and Bias

NOTE 6—Estimate of precision below was determined using a silver-

silver chloride electrode which is no longer commercially available.

13.1 Precision—Attempts to develop a precision and bias

statement for this test method have not been successful due to

the limited number of laboratories participating in round-robin

tests. Data on precision and bias cannot be given for this

reason. Anyone wishing to participate in the development of

precision and bias data should contact the Chairman, Subcom-

mittee D20.22 (Section D20.22.01), ASTM, 100 Barr Harbor

Drive, West Conshohocken, PA 19428.

13.2 A limited round-robin was conducted.

13.2.1 It has been estimated that duplicate results by the

same analyst shall be considered suspect if they differ by more

than 0.001 % hydrolyzable chlorine at the 0.001 to 0.2 % level.

13.2.2 It has been estimated that results reported by different

laboratories shall be considered suspect if they differ by more

than 0.003 % hydrolyzable chlorine.

13.3 Bias—There are no recognized standards by which to

estimate the bias of this test method.

14. Keywords

14.1 aromatic isocyanates; hydrolyzable chlorine; isocya-

nates; polyurethane raw materials; titration; toluene diisocya-

nate

Reagent Chemicals, American Chemical Society Speciﬁcations, American

Chemical Society, Washington, DC. For suggestions on the testing of reagents not

listed by the American Chemical Society, see Analar Standards for Laboratory

Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia

and National Formulary, U.S. Pharmaceutical Convention, Inc. (USPC), Rockville,

MD.

D4663 − 20

SUMMARY OF CHANGES

Committee D20 has identiﬁed the location of selected changes to this standard since the last issue (D4663 - 15)

that may impact the use of this standard. (April 1, 2020)

(1) Various editorial changes throughout the standard.

(2) Subsection 2.1: ASTM Standards—Added E456 and E2935

as references per D4968.

(3) Section 3: Terminology—Modiﬁed as per D4968.

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This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,

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D4663 − 20

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摘要：

ASTM D4663 - 20 是一项由美国材料与试验协会（ASTM）发布的标准化测试方法，主要针对聚氨酯泡沫材料的密度测定。该标准规范了如何通过测量试样的质量和体积来计算其表观密度，适用于软质和硬质聚氨酯泡沫。本测试方法对于确保聚氨酯泡沫在隔热、包装、汽车及建筑等应用中的质量控制、性能评估和一致性至关重要。ASTM D4663 - 20 提供了详细的样品制备、测试条件和计算步骤，帮助实验室和制造商准确评估材料的特性，从而优化生产工艺并满足行业合规要求。

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