Yuan Lei's Little Knowledge | Oil Absorption Value of Powder
oil absorption value
Oil absorption is usually expressed in the mass of linseed oil required for 100g of pigment.(% or g/100g). That is, per 100g of pigment, the minimum amount of oil required to achieve complete wetting.
OA = amount of linseed oil/100g pigment
There are many factors that affect the oil absorption of powder, such as the compactness of its structure. It is also related to its surface shape, fineness, etc. The finer the particles of the pigment, the larger the surface area and the narrower the distribution, the higher the oil absorption. Cylindrical than needle-like oil absorption is high, and needle-like particles than the oil absorption of spherical particles to be high, because of the porosity between them. In addition, the oil absorption also has a great relationship with the specific gravity of the powder, the larger the specific gravity of the powder, the lower the general oil absorption.
(1) Determination of oil absorption:
In 100g of pigment, linseed oil is added drop by drop and mixed with a scraper at any time. When oil is added at the beginning, the pigment is still in a loose state. With the continuous addition of linseed oil, all pigments can be bonded together into a spherical shape. If oil is added again, the system will become thinner. The amount of linseed oil used at this time is the oil absorption of this pigment.
In practical application, the oil absorption is mainly to estimate the adsorption amount of powder to resin, I .e. the volume concentration (PVC) of pigment and resin in the coating. Therefore, the oil absorption amount of powder has a great influence on the performance of the coating film and also has a great influence on the viscosity during the production of the coating. During the drying process of the coating film, the resin should not only be completely coated on the powder surface, but also fill the gaps between particles, when the powder oil absorption is large, more resin is needed to complete these functions, so the oil absorption of the powder is a very important factor affecting the coating.
Oil absorption of various powders
Knowledge, oil, pigment, 100g, resin, effect, particle, larger, linseed oil, added
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