ASTM D5629-23

Standard Test Method for Polyurethane Raw Materials: Determination of Acidity in Low-Acidity Aromatic Isocyanates and Polyurethane Prepolymers

SIGNIFICANCE AND USE
5.1 This test method is suitable for research or for quality control to characterize aromatic isocyanates and low-acidity prepolymers. Acidity correlates with performance in some polyurethane systems.
SCOPE
1.1 This test method measures the acidity, expressed as ppm of hydrochloric acid (HCl), in aromatic isocyanate or polyurethane prepolymer samples of below 100 ppm acidity. The test method is applicable to products derived from toluene diisocyanate and methylene di(phenylisocyanate) (see Note 1). Refer to Test Method D6099 for determination of acidity in moderate- to high-acidity aromatic isocyanates.  
1.2 The values stated in SI units are to be regarded as the standard.  
1.3 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 appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
Note 1: This standard is equivalent to ISO 14898, Method B.  
1.4 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.

General Information

• Status: Published
• Publication Date: 28-Feb-2023
• ICS: 83.080.10 - Thermosetting materials
• Technical Committee: D20 - Plastics
• Drafting Committee: D20.22 - Cellular Materials - Plastics and Elastomers

Standards Content (Sample)

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.
Designation: D5629 − 23
Standard Test Method for
Polyurethane Raw Materials: Determination of Acidity in
Low-Acidity Aromatic Isocyanates and Polyurethane
1
Prepolymers
This standard is issued under the fixed designation D5629; 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* Methods for Analysis and Testing of Industrial and Spe-
3
cialty Chemicals (Withdrawn 2009)
1.1 This test method measures the acidity, expressed as ppm
E456 Terminology Relating to Quality and Statistics
of hydrochloric acid (HCl), in aromatic isocyanate or polyure-
E691 Practice for Conducting an Interlaboratory Study to
thane prepolymer samples of below 100 ppm acidity. The test
Determine the Precision of a Test Method
method is applicable to products derived from toluene diiso-
E2935 Practice for Evaluating Equivalence of Two Testing
cyanate and methylene di(phenylisocyanate) (see Note 1).
Processes
Refer to Test Method D6099 for determination of acidity in
4
2.2 ISO Standards:
moderate- to high-acidity aromatic isocyanates.
ISO 14898 Plastics—Aromatic Isocyanates for Use in the
1.2 The values stated in SI units are to be regarded as the
Production of Polyurethane—Determination of Acidity
standard.
1.3 This standard does not purport to address all of the
3. Terminology
safety concerns, if any, associated with its use. It is the
3.1 Definitions—Terms used in this standard are defined in
responsibility of the user of this standard to establish appro-
accordance with Terminology D883, unless otherwise speci-
priate safety, health, and environmental practices and deter-
fied. For terms relating to precision and bias and associated
mine the applicability of regulatory limitations prior to use.
issues, the terms used in this standard are defined in accordance
NOTE 1—This standard is equivalent to ISO 14898, Method B. with Terminology E456.
1.4 This international standard was developed in accor-
3.2 Definitions of Terms Specific to This Standard:
dance with internationally recognized principles on standard-
3.2.1 acidity, n—the acid strength of a sample expressed in
ization established in the Decision on Principles for the
ppm HCl.
Development of International Standards, Guides and Recom-
mendations issued by the World Trade Organization Technical
4. Summary of Test Method
Barriers to Trade (TBT) Committee.
4.1 The isocyanate is mixed with an excess of n-propanol, a
cosolvent and a known amount of HCl. Additional acid is
2. Referenced Documents
released into the solvent system during urethane formation.
2
2.1 ASTM Standards:
The acid is then titrated potentiometrically with methanolic
D883 Terminology Relating to Plastics
KOH. The same procedure is performed with a blank solution
D6099 Test Method for Polyurethane Raw Materials: Deter-
and the difference in titer is used to calculate the acidity present
mination of Acidity in Moderate to High Acidity Aromatic
in the isocyanate sample.
Isocyanates
E180 Practice for Determining the Precision of ASTM
5. Significance and Use
5.1 This test method is suitable for research or for quality
control to characterize aromatic isocyanates and low-acidity
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 - prepolymers. Acidity correlates with performance in some
Plastics and Elastomers.
polyurethane systems.
Current edition approved March 1, 2023. Published March 2023. Originally
approved in 1994. Last previous edition approved in 2016 as D5629 - 16. DOI:
10.1520/D5629-23.
2 3
For referenced ASTM standards, visit the ASTM website, www.astm.org, or The last approved version of this historical standard is referenced on www.ast-
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM m.org.
4
Standards volume information, refer to the standard’s Document Summary page on Available from American National Standards Institute (ANSI), 25 W. 43rd St.,
the ASTM website. 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
1

---------------------- Page: 1 ----------------------
D5629 − 23
6. Apparatus 11. Procedure
6.1 Disposable Beakers, 250 mL. 11.1 Make a blank determination in conjunction with each
series of samples. Prepare the blank in the
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: D5629 − 16 D5629 − 23
Standard Test Method for
Polyurethane Raw Materials: Determination of Acidity in
Low-Acidity Aromatic Isocyanates and Polyurethane
1
Prepolymers
This standard is issued under the fixed designation D5629; 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 measures the acidity, expressed as ppm of hydrochloric acid (HCl), in aromatic isocyanate or polyurethane
prepolymer samples of below 100 ppm acidity. The test method is applicable to products derived from toluene diisocyanate and
methylene di(phenylisocyanate) (see Note 1). Refer to Test Method D6099 for determination of acidity in moderate- to high-acidity
aromatic isocyanates.
1.2 The values stated in SI units are to be regarded as the standard.
1.3 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 appropriate safety and healthsafety, health, and environmental practices and determine
the applicability of regulatory limitations prior to use.
NOTE 1—This standard is equivalent to ISO 14898, Method B.
1.4 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.
2. Referenced Documents
2
2.1 ASTM Standards:
D883 Terminology Relating to Plastics
D6099 Test Method for Polyurethane Raw Materials: Determination of Acidity in Moderate to High Acidity Aromatic
Isocyanates
E180 Practice for Determining the Precision of ASTM Methods for Analysis and Testing of Industrial and Specialty Chemicals
3
(Withdrawn 2009)
E456 Terminology Relating to Quality and Statistics
E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
E2935 Practice for Evaluating Equivalence of Two Testing Processes
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, 2016March 1, 2023. Published April 2016March 2023. Originally approved in 1994. Last previous edition approved in 20112016 as
D5629 - 11.D5629 - 16. DOI: 10.1520/D5629-16.10.1520/D5629-23.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
3
The last approved version of this historical standard is referenced on www.astm.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
1

---------------------- Page: 1 ----------------------
D5629 − 23
4
2.2 ISO Standards:
ISO 14898 Plastics—Aromatic Isocyanates for Use in the Production of Polyurethane—Determination of Acidity
3. Terminology
3.1 Definitions—The terminology in this test method follows the standard terminology defined in Terms used in this standard are
defined in accordance with Terminology D883, unless otherwise specified. 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 acidity, n—the acid strength of a sample expressed in ppm HCl.
4. Summary of Test Method
4.1 The isocyanate is mixed with an excess of n-propanol, a cosolvent and a known amount of HCl. Additional acid is released
into the solvent system during urethane formation. The acid is then titrated potentiometrically with methanolic KOH. The same
procedure is performed with a blank solution and the difference in titer is used to calculate the acidity present in the isocyanate
sample.
5. Significance and Use
5.1 This test method is suitable for research or for quality control to characterize aromatic isocyanates and low-acidity
prepolymers. Acidity correlates with performance in some polyurethane systems.
6. Apparatus
6.1 Disposable
...