ASTM D2572-19

Standard Test Method for Isocyanate Groups in Urethane Materials or Prepolymers

SIGNIFICANCE AND USE
4.1 The percent NCO is used to establish unit ratios for stoichiometric reactions with co-reactants.
SCOPE
1.1 This test method covers the determination of the isocyanate group (NCO) content of a urethane intermediate or prepolymer.  
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this 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. For specific hazard statements, see Section 8.  
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: 30-Sep-2019
• ICS: 71.080.99 - Other organic chemicals
• Technical Committee: D01 - Paint and Related Coatings, Materials, and Applications
• Drafting Committee: D01.33 - Polymers and Resins

Relations

• Replaces: ASTM D2572-97(2010) - Standard Test Method for Isocyanate Groups in Urethane Materials or Prepolymers (Withdrawn 2019)
• Effective Date: 01-Oct-2019
• Refers: ASTM D841-19 - Standard Specification for Nitration Grade Toluene
• Effective Date: 15-Nov-2019
• Refers: ASTM D841-17a - Standard Specification for Nitration Grade Toluene
• Effective Date: 01-Jul-2017
• Refers: ASTM D841-17 - Standard Specification for Nitration Grade Toluene
• Effective Date: 01-Jun-2017
• Refers: ASTM D841-13 - Standard Specification for Nitration Grade Toluene
• Effective Date: 01-Feb-2013
• Refers: ASTM D841-12 - Standard Specification for Nitration Grade Toluene
• Effective Date: 01-Nov-2012
• Refers: ASTM D841-11 - Standard Specification for Nitration Grade Toluene
• Effective Date: 01-Jul-2011
• Refers: ASTM D841-10 - Standard Specification for Nitration Grade Toluene
• Effective Date: 01-Jan-2010
• Refers: ASTM D841-02(2008)e1 - Standard Specification for Nitration Grade Toluene
• Effective Date: 01-Jan-2008
• Refers: ASTM D841-02 - Standard Specification for Nitration Grade Toluene
• Effective Date: 10-Jan-2002

Overview

ASTM D2572-19: Standard Test Method for Isocyanate Groups in Urethane Materials or Prepolymers provides a reliable methodology for determining the isocyanate group (NCO) content in urethane intermediates and prepolymers. Published and maintained by ASTM International, this standard is widely adopted by industries manufacturing urethane-based products for ensuring precise formulation and quality control. The method is crucial for establishing accurate stoichiometric ratios during the synthesis of polyurethane materials, enhancing the performance and consistency of final products.

Key Topics

• Scope and Purpose:

  • The standard specifies the determination of isocyanate group content in urethane intermediates or prepolymers.
  • Results are expressed in SI units only.
  • Emphasizes the importance of safety, health, and environmental practices during the testing process.

• Test Method Summary:

  • The test involves reacting the urethane prepolymer sample with an excess of di-n-butylamine in toluene.
  • After reaction completion, the remaining di-n-butylamine is quantified via back titration using standard hydrochloric acid and a bromphenol blue indicator.
  • The NCO content is calculated based on titration values, providing precise data for material formulation.

• Significance and Use:

  • Percent NCO determination is critical for calculating stoichiometric ratios with co-reactants in polyurethane production.
  • Accurate NCO measurements help ensure targeted chemical reactions and product consistency.

• Safety Considerations:

  • Users must observe proper safety precautions due to the hazardous nature of diisocyanates and solvents involved in the test.
  • Implementation of appropriate personal protective equipment (PPE) and ventilation is essential.

Applications

• Urethane Production:

  • Enables quality assurance for precursors in polyurethane foams, coatings, adhesives, and elastomers by monitoring NCO group content.
  • Provides manufacturers with pivotal data for optimizing chemical formulations and reaction efficiencies.

• Research and Development:

  • Supports the development of new urethane materials with controlled reactivity and mechanical properties.
  • Facilitates reliable comparison of different prepolymers and intermediates.

• Regulatory Compliance:

  • Helps organizations demonstrate adherence to internal and external quality standards.
  • Assists in meeting requirements set by the U.S. Department of Defense and other regulatory bodies.

• Industrial Laboratories:

  • Adopted by quality control labs for batch release and verification of raw material specifications.

Related Standards

• ASTM D841: Specification for nitration grade toluene, referenced for solvent quality in this test method.
• ASTM D2572-19: Directly under the jurisdiction of ASTM Committee D01 on Paint and Related Coatings, Materials, and Applications.
• ISO Standards on Polyurethane Testing: Complementary to international guidelines for polyurethane material testing and quality assurance.

Summary

Implementing ASTM D2572-19 ensures accurate determination of isocyanate content in urethane intermediates and prepolymers. By following this well-defined standard, manufacturers and laboratories can enhance product performance, support regulatory compliance, and improve material consistency throughout the polyurethane supply chain. This test method remains an essential tool in ensuring the reliability and quality of urethane materials in a wide range of applications.

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: D2572 − 19
Standard Test Method for
Isocyanate Groups in Urethane Materials or Prepolymers
This standard is issued under the fixed designation D2572; 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.
This standard has been approved for use by agencies of the U.S. Department of Defense.
not been evaluated using them.
1. Scope
1.1 This test method covers the determination of the isocya-
4. Significance and Use
nate group (NCO) content of a urethane intermediate or
4.1 The percent NCO is used to establish unit ratios for
prepolymer.
stoichiometric reactions with co-reactants.
1.2 The values stated in SI units are to be regarded as
standard. No other units of measurement are included in this
5. Interferences
standard.
5.1 Phosgene, the carbamyl chloride of isocyanate, hydro-
1.3 This standard does not purport to address all of the
gen chloride, or any other acidic or basic impurities of
safety concerns, if any, associated with its use. It is the
sufficient strength will interfere. The concentration of these
responsibility of the user of this standard to establish appro-
compounds is usually sufficiently low that their effect on the
priate safety, health, and environmental practices and deter-
determination is negligible.
mine the applicability of regulatory limitations prior to use.
For specific hazard statements, see Section 8.
6. Apparatus
1.4 This international standard was developed in accor-
6.1 Polyethylene Stoppers (or corks) covered with alumi-
dance with internationally recognized principles on standard-
num foil to fit 250-mL Erlenmeyer flasks.
ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom-
6.2 Magnetic Stirrer with PTFE-fluorocarbon-covered stir-
mendations issued by the World Trade Organization Technical
ring bar.
Barriers to Trade (TBT) Committee.
6.3 Pipet, 25-mL.
2. Referenced Documents 6.4 Buret, 50- or 100-mL.
2.1 ASTM Standards: 6.5 Analytical Balance.
D841 Specification for Nitration Grade Toluene
7. Reagents
3. Summary of Test Method
7.1 Purity of Reagents—Reagent grade chemicals shall be
3.1 The urethane prepolymer is allowed to react with an
used in all tests unless otherwise specified. Unless otherwise
excess of di-n-butylamine in toluene (Note 1). After the
indicated, it is intended that all reagents shall conform to the
reaction is complete, the excess of di-n-butylamine is deter-
specifications of the Committee on Analytical Reagents of the
mined by back titration with standard hydrochloric acid.
American Chemical Society, where such specifications are
available. Other grades may be used, provided that it is first
NOTE 1—Solvents other than toluene may be needed in some cases, for
ascertained that the reagent is of sufficiently high purity to
example, anhydrous dimethylformamide (DMF), but the procedure has
permit its use without lessening the accuracy of the determi-
nation.
This test method is under the jurisdiction of ASTM Committee D01 on Paint
and Related Coatings, Materials, andApplications and is the direct responsibility of
Subcommittee D01.33 on Polymers and Resins.
Current edition approved Oct. 1, 2019. Published October 2019. Originally Burets and pipets shall conform to National Institute of Standards and
approved in 1967. Last previous edition approved in 2010 as D2572 – 97 (2010) Technology tolerances.
which was withdrawn in July 2019 and reinstated October 2019. DOI: 10.1520/ ACS Reagent Chemicals, Specifications and Procedures for Reagents and
D2572-19. Standard-Grade Reference Materials, American Chemical Society, Washington,
For referenced ASTM standards, visit the ASTM website, www.astm.org, or DC. For suggestions on the testing of reagents not listed by theAmerican Chemical
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Society, see Analar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset,
Standards volume information, refer to the standard’s Document Summary page on U.K., and the United States Pharmacopeia and National Formulary, U.S. Pharma-
the ASTM website. copeial Convention, Inc. (USPC)
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