Resins, especially grinding resins, play a key role in preparing color pastes.
1) Participate in the dispersion and anchoring of pigments
2) Participate in maintaining the stability of dispersed and isolated pigment particles
You can see the above-mentioned effects of resins through some experiments, such as long-oil alkyd resin, polyamide resin, amino resin, aldehyde-ketone resin, and low relative mass hydroxyl acrylic resin, all of which show good wetting ability for pigments. , while low hydroxyl value acrylic resin, thermoplastic acrylic resin, high relative mass polyester resin, high relative mass saturated polyester resin, vinyl copolymer resin, polyolefin resin, etc. all show poor wettability to pigments. The same pigment can produce different hues in different resin systems. Almost all carbon blacks, organic pigments and transparent iron oxides change their hues with different resin systems, especially the scattering hue. Therefore, choosing the appropriate dispersant is not only used to disperse and stabilize the pigment, but also to adjust the pigment to ultimately achieve the correct color we need, such as blackness, transparency, shading at 45°, etc. Therefore, the combination of dispersant and resin includes:
-Compatibility (sample testing, check compatibility after removing the solvent)
-The dispersant in the resin system determines the viscosity reduction behavior of the pigment (rotational viscometer detection)
-The dispersant in the resin system determines the color development behavior of the pigment (scratching color comparison)
-Storage stability (flow plate method)
When the resin system changes, the above performance of the dispersant will change accordingly. Such changes require application testing to determine.
Generally, it is not easy to summarize a simple application principle. For the resin system plus the pigment factor, the choice of dispersant becomes too many parameters. Therefore, the properties of pigments and fillers must be considered at the same time.