DIN Standards Committee Pigments and Extenders
DIN EN ISO 4629-1
Binders for paints and varnishes - Determination of hydroxyl value - Part 1: Titrimetric method without using a catalyst (ISO 4629-1:2016); German version EN ISO 4629-1:2016
Bindemittel für Beschichtungsstoffe - Bestimmung der Hydroxylzahl - Teil 1: Titrimetrisches Verfahren ohne Katalysator (ISO 4629-1:2016); Deutsche Fassung EN ISO 4629-1:2016
Overview
This part of ISO 4629 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.
The hydroxyl groups contained in a test portion are acetylated with acetic anhydride. The excess acetic anhydride is hydrolysed and the resulting acetic acid is titrated with potassium hydroxide solution, either in the presence of a colour indicator or potentiometrically.
The responsible German standardization committee is Working Committee NA 002-00-02 AA "Lackrohstoffe" ("Raw materials for paints and varnishes") at DIN Standards Committee Coatings and Coating Materials (NAB).
Document: references other documents
Document: referenced in other documents
Responsible national committee
NA 002-00-02 AA - Raw materials for paints and varnishes
Responsible european committee
CEN/TC 139 - Paints and varnishes
