ISO 4629-1:2016 PDF

Binders for paints and varnishes — Determination of hydroxyl value — Part 1: Titrimetric method without using a catalyst

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Title (English):

ISO 4629-1:2016

Binders for paints and varnishes — Determination of hydroxyl value — Part 1: Titrimetric method without using a catalyst

Document status:: Active
Format:: Electronic (PDF)
Number of pages:: 7
Publication date:: June 2, 2016
Edition:: ISO IS 4629 edition 1 version 1
ICS:: 87.060.20

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Description (English):

ISO 4629-1:2016 specifies a titrimetric method for determining the free hydroxyl groups in binders and binder solutions for paints and varnishes. The hydroxyl groups may be present as polyhydric alcohols, partial esters, polyester end groups or hydroxylated fatty acids. This method is not applicable to resins containing both hydroxyl groups and epoxy groups, because the latter will also be included in the result. Also the method is not applicable to cellulose nitrate or to phenolic resins. NOTE 1 If, in the case of binder solutions, the hydroxyl value of the binder only is to be determined, the possibility that other constituents of the binder solution may contain hydroxyl groups has to be taken into account. NOTE 2 A method for the determination of the hydroxyl value of epoxy resins is specified in ISO 7142[1].

Technical details

Technical committee: ISO/TC 35 - Paints and varnishes
SKU: ISO 4629-1:2016

Abstract

Overview

ISO 4629-1:2016 specifies a titrimetric method without a catalyst for determining the hydroxyl value of binders and binder solutions used in paints and varnishes. The method quantifies free hydroxyl groups (e.g., polyhydric alcohols, polyester end groups, hydroxylated fatty acids) by acetylation with acetic anhydride, hydrolysis of the excess reagent, and back-titration of the resulting acetic acid with potassium hydroxide. This Part 1 method is designed for routine laboratory quality control and formulation work where catalytic activation is not used.

Key topics and requirements

Scope and limitations
- Applicable to binders and binder solutions for paints and varnishes.
- Not applicable to resins that contain both hydroxyl and epoxy groups (epoxy groups would bias results), cellulose nitrate, or phenolic resins.
- When testing binder solutions, consider other constituents that may contain hydroxyl groups.
Analytical principle
- Acetylation of hydroxyl groups → hydrolysis of excess acetic anhydride → titration of acetic acid with KOH (potentiometric or indicator-based end point).
Reagents and apparatus
- Uses analytical-grade reagents and laboratory glassware as referenced (e.g., burettes, pipettes).
- Typical reagents: acetic anhydride-based acetylating reagent, potassium hydroxide in methanol (~0.5 mol/L), phenolphthalein or mixed indicators; potentiometric titration is an optional alternative.
Procedure essentials
- Duplicate determinations; use prescribed test portion masses (table provided in the standard) and 5.00 ± 0.02 ml acetylating reagent.
- Perform blank test and determine acid value (ISO 2114) for correction.
- Report mean of two valid replicates to nearest 1 mg KOH/g. If duplicates differ by >5% (relative), repeat.
Performance
- Precision varies with hydroxyl value (examples from interlaboratory study provided: repeatability and reproducibility figures).

Applications

Quality control testing in paint, varnish and binder production.
Raw material evaluation for formulation and specification compliance.
Formulation development and stability studies where hydroxyl number / hydroxyl value is critical (e.g., crosslinking stoichiometry, polyester and alkyd binder characterization).
Laboratories performing routine titrimetric and potentiometric analyses.

Related standards

ISO 4629-2 - Part 2: titrimetric method using a catalyst (complementary method).
ISO 7142 - Determination of hydroxyl value for epoxy resins (when epoxy groups are present).
ISO 2114 - Determination of acid value (used for correction in results).
Laboratory glassware and sampling references: ISO 385, ISO 648, ISO 3696, ISO 15528.

Keywords: ISO 4629-1:2016, hydroxyl value, binders for paints and varnishes, titrimetric method, acetylation, potassium hydroxide titration, potentiometric titration, paint binder testing.

Related standards

Standards mentioned in the description

Abstract

Overview

Key topics and requirements

Scope and limitations
- Applicable to binders and binder solutions for paints and varnishes.
- Not applicable to resins that contain both hydroxyl and epoxy groups (epoxy groups would bias results), cellulose nitrate, or phenolic resins.
- When testing binder solutions, consider other constituents that may contain hydroxyl groups.
Analytical principle
- Acetylation of hydroxyl groups → hydrolysis of excess acetic anhydride → titration of acetic acid with KOH (potentiometric or indicator-based end point).
Reagents and apparatus
- Uses analytical-grade reagents and laboratory glassware as referenced (e.g., burettes, pipettes).
- Typical reagents: acetic anhydride-based acetylating reagent, potassium hydroxide in methanol (~0.5 mol/L), phenolphthalein or mixed indicators; potentiometric titration is an optional alternative.
Procedure essentials
- Duplicate determinations; use prescribed test portion masses (table provided in the standard) and 5.00 ± 0.02 ml acetylating reagent.
- Perform blank test and determine acid value (ISO 2114) for correction.
- Report mean of two valid replicates to nearest 1 mg KOH/g. If duplicates differ by >5% (relative), repeat.
Performance
- Precision varies with hydroxyl value (examples from interlaboratory study provided: repeatability and reproducibility figures).

Applications

Quality control testing in paint, varnish and binder production.
Raw material evaluation for formulation and specification compliance.
Formulation development and stability studies where hydroxyl number / hydroxyl value is critical (e.g., crosslinking stoichiometry, polyester and alkyd binder characterization).
Laboratories performing routine titrimetric and potentiometric analyses.

Related standards

ISO 4629-2 - Part 2: titrimetric method using a catalyst (complementary method).
ISO 7142 - Determination of hydroxyl value for epoxy resins (when epoxy groups are present).
ISO 2114 - Determination of acid value (used for correction in results).
Laboratory glassware and sampling references: ISO 385, ISO 648, ISO 3696, ISO 15528.

Keywords: ISO 4629-1:2016, hydroxyl value, binders for paints and varnishes, titrimetric method, acetylation, potassium hydroxide titration, potentiometric titration, paint binder testing.

ISO 4629-1:2016 PDF

Technical details

Abstract

Overview

Key topics and requirements

Applications

Related standards

Related standards

Abstract

Overview

Key topics and requirements

Applications

Related standards

Related standards

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