ASTM D3643-15(2022)

Standard Test Method for Acid Number of Certain Alkali-Soluble Resins

SIGNIFICANCE AND USE
4.1 This test method is not appropriate for alkali-soluble resins whose acid functionality is due to incorporated anhydrides. Variations in manufacture, storage, and possible contamination of anhydride functional resins may cause partial hydrolysis, or esterification, which will invalidate data from this test method. Anhydride functional resins should be characterized by Test Method D3644.  
4.2 This test method is used to measure a property of acid functionalized resins. Acid number determines the utility of resins as well as being a significant quality control measure.
SCOPE
1.1 This test method covers the measurement of the free acidity present in certain alkali-soluble resins.  
1.2 This test method is not suitable for styrene-maleic anhydride resins.  
1.3 The resin manufacturer should specify whether or not this test method may be used for his product(s).  
1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.5 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.  
1.6 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-Nov-2022
• ICS: 83.080.10 - Thermosetting materials
• Technical Committee: D21 - Polishes
• Drafting Committee: D21.02 - Raw Materials

Relations

• Refers: ASTM D3644-06(2012) - Standard Test Method for Acid Number of Styrene-Maleic Anhydride Resins
• Effective Date: 01-Oct-2012
• Refers: ASTM D3644-06 - Standard Test Method for Acid Number of Styrene-Maleic Anhydride Resins
• Effective Date: 01-Jun-2006
• Refers: ASTM D1152-06 - Standard Specification for Methanol (Methyl Alcohol)
• Effective Date: 01-Apr-2006
• Refers: ASTM D1193-06 - Standard Specification for Reagent Water
• Effective Date: 01-Mar-2006
• Refers: ASTM D3644-98(2004) - Standard Test Method for Acid Number of Styrene-Maleic Anhydride Resins
• Effective Date: 01-Sep-2004
• Refers: ASTM D1193-99 - Standard Specification for Reagent Water
• Effective Date: 10-Feb-1999
• Refers: ASTM D1193-99e1 - Standard Specification for Reagent Water
• Effective Date: 10-Feb-1999
• Refers: ASTM D3644-98 - Standard Test Method for Acid Number of Styrene-Maleic Anhydride Resins
• Effective Date: 10-Sep-1998
• Refers: ASTM D1152-97(2001) - Standard Specification for Methanol (Methyl Alcohol)
• Effective Date: 10-Dec-1997

Overview

ASTM D3643-15(2022), Standard Test Method for Acid Number of Certain Alkali-Soluble Resins, specifies a reliable procedure for the determination of the acid number in selected alkali-soluble resins. The acid number, expressed as milligrams of potassium hydroxide (KOH) required to neutralize the acidic constituents in 1 gram of resin, is a critical measure for evaluating resin properties and ensuring product consistency. This ASTM standard applies to resins with acid functionalities, excluding those with incorporated anhydrides or styrene-maleic anhydride resins.

This international standard supports laboratories and manufacturers in quality control and formulation, ensuring compliance with globally recognized guidelines for testing procedures.

Key Topics

• Scope and Limitations:

  • Applicable only to alkali-soluble resins with acid functionalities unrelated to anhydrides.
  • Not suitable for styrene-maleic anhydride resins or resins whose acid function arises from anhydrides-refer to ASTM D3644 for those types.
  • Resin manufacturers are responsible for confirming if this method is appropriate for their products.

• Definition:

  • The acid number measures the amount of KOH necessary to neutralize the alkali-reactive acid groups in the resin.

• Procedure Highlights:

  • Use of standardized titration involving phenolphthalein as the indicator and a neutral solvent mixture.
  • Calculation formula provided for determining the acid number based on sample weight, titrant volume, and normality.

• Quality Control:

  • Ensures the performance and suitability of resin batches for intended industrial applications.
  • Integral for monitoring formulation consistency and detecting contamination or variability during manufacturing and storage.

Applications

• Quality Assurance in Manufacturing:

  • Verifying acid number ensures that resins meet required specifications for use in coatings, adhesives, and polishes.
  • Supports batch certification and ongoing process verification.

• Research & Development:

  • Used in developing new alkali-soluble resins where understanding acid functionality is crucial to final product performance.
  • Facilitates comparative analysis between resin types and sources.

• Regulatory and Specification Compliance:

  • Ensures adherence to industry standards and customer requirements for resin acidity in a range of applications.
  • Supports documentation and reporting for export and regulatory acceptance.

Related Standards

• ASTM D3644:

  • Test Method for Acid Number of Styrene-Maleic Anhydride Resins - applicable for resins excluded from ASTM D3643.

• ASTM D1193:

  • Specification for Reagent Water - defines the quality of water used in the testing procedure.

• Other Withdrawn Specifications (Referenced):

  • ASTM D362 - Industrial Grade Toluene
  • ASTM D1152 - Methanol (Methyl Alcohol)

Practical Value

By implementing ASTM D3643-15(2022), organizations benefit from:

• Consistent Testing Protocols: Unifies laboratory methodology for determining acid number, promoting repeatability and credibility in results.
• Improved Product Performance: Enables manufacturers to fine-tune resin properties for specific industrial needs.
• Risk Mitigation: Early detection of contamination or improper resin functionality, reducing costly production errors.

Keywords: ASTM D3643, acid number, alkali-soluble resins, free acidity measurement, resin quality control, industrial resins, titration method, standard test method.

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: D3643 − 15 (Reapproved 2022)
Standard Test Method for
Acid Number of Certain Alkali-Soluble Resins
This standard is issued under the fixed designation D3643; 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 3. Terminology
1.1 This test method covers the measurement of the free 3.1 Definitions:
acidity present in certain alkali-soluble resins. 3.1.1 acid number—the number of milligrams of potassium
hydroxide (KOH) required to neutralize the alkali-reactive
1.2 This test method is not suitable for styrene-maleic
groups in1gof material under the conditions of test.
anhydride resins.
1.3 The resin manufacturer should specify whether or not 4. Significance and Use
this test method may be used for his product(s).
4.1 This test method is not appropriate for alkali-soluble
1.4 The values stated in SI units are to be regarded as resins whose acid functionality is due to incorporated anhy-
standard. No other units of measurement are included in this drides. Variations in manufacture, storage, and possible con-
standard. tamination of anhydride functional resins may cause partial
hydrolysis, or esterification, which will invalidate data from
1.5 This standard does not purport to address all of the
this test method. Anhydride functional resins should be char-
safety concerns, if any, associated with its use. It is the
acterized by Test Method D3644.
responsibility of the user of this standard to establish appro-
priate safety, health, and environmental practices and deter-
4.2 This test method is used to measure a property of acid
mine the applicability of regulatory limitations prior to use.
functionalized resins. Acid number determines the utility of
1.6 This international standard was developed in accor-
resins as well as being a significant quality control measure.
dance with internationally recognized principles on standard-
5. Reagents and Materials
ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom-
5.1 Purity of Reagents—Reagent grade chemicals shall be
mendations issued by the World Trade Organization Technical
used in all tests. Unless otherwise indicated, it is intended that
Barriers to Trade (TBT) Committee.
all reagents shall conform to the specifications of the Commit-
tee onAnalytical Reagents of theAmerican Chemical Society,
2. Referenced Documents
where such specifications are available.
2.1 ASTM Standards:
5.2 Purity of Water—Unless otherwise indicated, references
D362 SpecificationforIndustrialGradeToluene(Withdrawn
to water shall be understood to mean reagent water conforming
1989)
to Specification D1193.
D1152 Specification for Methanol (Methyl Alcohol) (With-
5.3 Neutral Solvent Mixture—Mix equal parts of denatured
drawn 2021)
alcohol and industrial toluene conforming respectively to the
D1193 Specification for Reagent Water
requirements described for SDA. 3A (200 proof) and Specifi-
D3644 Test Method for Acid Number of Styrene-Maleic
cation D362. Neutralize the mixture using 0.1 N KOH solution
Anhydride Resins
and phenolphthalein indicator solution, until the faint pink
color persists for 1 min.
5.4 Phenolphthalein Indicator Solution (10 g/L)—Dissolve
ThistestmethodisunderthejurisdictionofASTMCommitteeD21onPolishes
1.0 g of phenolphthalein in 100 mLof denatured alcohol (SDA
and is the direct responsibility of Subcommittee D21.02 on Raw Materials.
3A, 200 proof).
Current edition approved Dec. 1, 2022. Published December 2022. Originally
approved in 1978. Last previous edition approved in 2015 as D3643 – 15. DOI:
10.1520/D3643-15R22.
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For referen
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