Common problems in the application of thickeners in water-based paints

The type and characteristics of thickeners
thickeners are widely used in coatings, which have a great impact on the production, storage, construction and performance of coatings after filming. In coating applications, thickeners can improve the viscosity of the coating and adjust the fluid state of the coating, so that the coating can meet the production and construction conditions.
thickeners can be divided into connective and non-connective types according to the action .
addition to the above categories, there are some modified products. Such as hydrophobic modified cellulose, hydrophobic modified acrylic, are on the original basis, through the modified increase of part of the connective structure.
Searly the performance comparison of different types of thickeners:
thickeners on coatings
The use of thickeners can affect many properties of coatings, such as storage stability, viscosity stability, re-coarseness, covering force, roller splashing, paint film appearance, etc.
, storage stability
storage stability can be divided into pigmentation, water layering and so on. Common reasons for poor storage stability are:
1, paint itself design solid content, pigment density and particle size is not suitable;
2, low adhesion;
3, dispersant selection and addition of improper,
4, thickener selection is not appropriate.
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. Among them, the choice of thickener has a great impact on storage stability.
, which can provide better anti-sinking, and good water preservation is more conducive to preventing the water layering of lacquer liquid.
acrylic thickeners have good false plasticity and water preservation, in improving the stability of coating storage has excellent performance, such as SV-114, SV-125 and other products in a single-part anti-corrosion paint have very good applications. However, acrylic thickeners are less commonly used in high-grade coatings due to poor leveling.
low-cut polyurethane thickener can also provide strong false plasticity, in order to ensure the flow level effect, the premise of giving the coating excellent storage stability. The selection of polyurethane thickeners to improve the storage stability of coatings should be based on low shear thickeners.
, viscosity stability
construction viscosity, has a great impact on construction. Viscosity stability is one of the most important properties to demonstrate coating quality.
and system compatible is conducive to the viscosity stability of lacquer liquid, most of the market low-shear polyurethane thickener and water compatible difference, must be used with the help of solvent thinning, often there will be thickener in the paint solution correspondingly slower, poor mixing situation. This also leads to the thickening of many polyurethane thickeners.
For this kind of problem, we recommend SV-1135, SV-1540, it thickens well, and is compatible with water, thickening response is fast, storage viscosity is stable, can be directly added or water can be used thin, very convenient to use.
, the phenomenon of
back to coarseness is common in water-like, oily paint, which is more likely to produce water-like paint. Powder characteristics, dispersant types and dosages are the most important factors.
addition of thickeners during the production process is also one of its factors. Part of the thickener in the process of addition is not easy to disperse, resulting in local thickening serious, affecting the edict of the coating, may cause back thickening.
, cover force
cover force is not only related to the pigment itself, but also has a direct relationship with the dispersion effect of pigments in production. The smaller the pigment dispersion finer, the more uniform the particle size distribution, the better the covering force. Therefore, the dispersion effect and re-coarseness are the main factors affecting the cover force.
thickeners have a great impact on the stability, suspension and dispersion of pigment fillers, and the use of suitable thickeners can make pigments better dispersed and stable in lacquer liquid to a certain extent. This ensures the cover force during construction.
addition, for the thickener, which is more serious after thickening, due to the high stickiness during construction, it needs to be diluted with excessive water, and will objectively cause the disadvantages of insufficient cover.
, the choice of thickeners that are easy to disperse, thicken quickly and thicken without thickening has a good effect on this problem, and SV-1135 and SV-1540 have been well verified in many practices.
5, roller-coated splash
cellulose, acrylic thickeners because of the large molecular weight, easy to produce splashes in coating, polyurethane thickeners have excellent anti-splash performance.
in addition, polyurethane thickeners can provide products with different fluidity states, by choosing to add high shearing fluidizers, can effectively improve the viscosity of high shear construction, thus avoiding paint splashes.
6, paint film appearance
inorganic thickener, cellulose, acrylic thickener acting on the paint false plasticity, limiting the flow of wet film, resulting in poor leveling;
polyurethane-combined thickeners have an excellent appearance. The main reasons are:
1, its molecular weight is low, does not affect the fluidity of the coating,
2, with latex particles involved in conceding, will not produce flocculation, so that the coating film smooth, has a high gloss;
3, its joining structure under the influence of shear force is destroyed, the viscosity is reduced, when the shear force disappears viscosity can be restored. It can prevent the phenomenon of flow hanging in the construction process, and its viscosity recovery has a certain lag, which is conducive to coating film leveling.
can be
that thickeners affect all aspects of coatings. The rational selection of thickeners is of great significance for production, storage and construction applications, and many performance needs to be taken into account. The more comprehensive the formulation is considered, the fewer subsequent problems there will be.
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