introduction
ISO (International Organization for Standardization) is a global alliance of national standards bodies (ISO member bodies). The development of international standards is usually carried out through ISO technical committees. Each member institution interested in a subject on which a technical committee has been established has the right to be represented on that committee. International governmental and non-governmental organizations liaising with ISO are also involved in this work. ISO works closely with the International Electrotechnical Commission (IEC) on all matters of electrical standardization.

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ISO 4629-2-2016 “Paint base for paints and varnishes – Determination of hydroxyl values – titration method”

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The committee responsible for this document is ISO/TC 35, Paints and Varnishes, Subcommittee SC 10, Methods of Testing adhesives for Paints and varnishes.

ISO 4629 consists of the following parts, under the general heading Paint and varnish binders – Determination of hydroxyl values:

– Part 1: titration without catalyst

– Part 2: titration using catalysts

ISO 4629-2-2016 “Paint base for paints and varnishes – Determination of hydroxyl values – titration method”

introduce
There are several different standardized ways to determine the hydroxyl value of a resin. The classical method of using catalyst-free pyridine is specified in ISO 4629-1. The advantages of the method using catalysts are as follows:

– The solvents used are less harmful to health;

– Lower solvent consumption;

– The method is faster due to shorter reaction time;

– The end of the titration is easier to see;

– Polyols dissolve more easily.

1 Range
This part of ISO 4629 specifies titration methods for determining hydroxyl values of resins, paints and varnishes adhesives, primary alcohols, glycols and fats. Application to hydrocarboxylic acids, phenolic hydroxyl groups, polyols such as trimethylpropane and substances containing aromatic groups that have been activated for the Fouck acylation reaction should be determined on a case-by-case basis.

Under appropriate conditions, the method can also be used to determine the hydroxyl values of castor oil and its derivatives.

ISO 4629-2-2016 “Paint base for paints and varnishes – Determination of hydroxyl values – titration method”

2 Normative references
All or part of the following documents are referred to normatively in this document and are required for their application. For dated references, only the cited version applies. For undated references, a new version of the reference (including any revisions) applies.

ISO 660, animal and vegetable fats and oils – Determination of acid value and acidity

ISO 2114:2000, plastics (polyester resins) and paints and varnishes (adhesives). Determination of partial and total acid values

ISO 3696, analytical laboratory water – Specifications and test methods

ISO 4618, paints and varnishes – Terms and definitions

ISO 15528, Paints, varnishes and raw materials for paints and varnishes – Sampling

ISO 4629-2-2016 “Paint base for paints and varnishes – Determination of hydroxyl values – titration method”

3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 4618 and the following articles apply.

3.1 Hydroxyl value

In 1 gram of the product under test, the number of milligrams of potassium hydroxide (KOH) corresponding to the acetylated hydroxyl group under the specified test conditions

[Source: ISO 4629-1:2016, 3.1]

ISO 4629-2-2016 “Paint base for paints and varnishes – Determination of hydroxyl values – titration method”

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