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1.
2.
Analysis of the cause of water separation in latex paint
(1) Latex paint formulation system
Thickening system: latex paint has a low viscosity and does not rely on the viscous force provided by a high-viscosity system.
The pigment and filler particles with a larger specific gravity than water and emulsion will settle due to gravity.
Dispersion and wetting system: The main function of dispersant and wetting agent is to help the pigment and filler particles to be well wetted by water, forming an electrostatic repulsion effect, so that the pigment and filler particles are uniformly dispersed in the water, and preventing their agglomeration and sedimentation.
Otherwise, water separation may occur.
(2) Storage deterioration
If the antibacterial preservatives in the latex paint are not added properly or exceed the storage period, it is possible that the latex paint will separate due to the growth of bacteria.
(3) Production process
Reasonable stirring speed: high speed (above 1200RPM) is used in the pigment dispersion stage to ensure uniform dispersion of pigment and filler particles and to disperse the agglomerated particles.
The beating stage is the thickening and mixing stage after adding the emulsion, and the post-processing stage.
Too fast speed will cause the stable emulsion system to break (below 800rpm).
Reasonable order and method of adding raw materials: Add dispersing wetting agent before pigments and fillers are dispersed, otherwise it may be difficult to disperse due to local adsorption or thick consistency after pigments and fillers are added, causing the dispersing wetting agent to not function effectively.
The pigments and fillers that are difficult to disperse are added as early as possible.
The order of dispersion of pigments and fillers is titanium dioxide, kaolin, wollastonite, and heavy calcium powder.
They should also be added in this order.
Adding method of thickener: The correct method of adding bactericide and thickener is to dilute with 1-2 times of water before adding, otherwise excessive association reaction may occur due to excessive local concentration or the electric balance of emulsion colloid may be damaged.
Demulsification or water separation occurred.
3.
How to solve the water separation of latex paint
(1) Formula system problem The
appropriate amount of thickener, and the use of cellulose and alkali swelling together, ensure that the viscosity is between 80-110KU.
A reasonable amount of dispersing wetting agent should be at least 5 kg.
(2) Storage problem: The
antiseptic and fungicides should be above 1.
5kg (Kasone), and the type should be selected appropriately.
(3) Process conditions