The non-volatile content of coatings is one of the important indicators to evaluate the film-forming performance and quality of coatings. It reflects the percentage of components in the coating that do not evaporate with volatiles after curing under certain conditions. Accurate determination of non-volatile content is essential for quality control in the coating production process, which has a direct impact on the durability, appearance and application performance of the coating film.
According to the national standards GB/T 1725-2007 and GB/T 9272-2007, the determination of non-volatile content of coatings can be carried out by gravimetric method and volume method.
Gravimetric method:
Principle: The volatile components in the sample are removed at a certain temperature by using the method of heating and baking, and the ratio of the mass of the residue to the total mass of the sample is obtained.
Operation procedure: A small amount of sample is evenly coated in a pre-weighed and dried container, and placed at a specified temperature for baking until the sample quality is constant. The non-volatile content is calculated by weighing and the result is expressed as a percentage by mass.
Capacity Method:
Principle: The volume fraction of non-volatile matter is determined by measuring the density change of the coating film.
Procedure: The mass and volume of the painted disc are first determined, then it is dried at a specified temperature and time, and the mass and volume are measured again. From this data, the integral number of non-volatile objects of the paint is calculated, and the result is expressed as a percentage of volume.
The non-volatile content of a coating is not an absolute value, but depends on the heating temperature and time at the time of measurement. High temperatures or prolonged heating may lead to further decomposition or volatilization of volatiles, which can affect the final measurement results. Therefore, in practical applications, the determination must be carried out in strict accordance with standard operating procedures to ensure the accuracy and comparability of the results.
The stability of the non-volatile content directly affects the viscosity and performance of the coating product. During the coating process, the film-forming substance content of the coating can be adjusted by quantitatively determining the non-volatile content, thereby controlling the thickness and quality of the coating film. This is important to ensure uniformity, adhesion and durability of coatings, especially in applications in the industrial and construction sectors.
In summary, the accurate determination of the non-volatile content of coatings is one of the key steps in the production and application of coatings. Gravimetric method and volumetric method are two commonly used measurement methods, each with its own applicable scenarios and operational requirements. By strictly controlling the measurement conditions and accurately calculating the analysis results, the quality stability and performance superiority of the coating products can be ensured, so as to meet the high requirements of coating quality in different application scenarios.