After the normal paint can be opened, the appearance is smooth and delicate, and the top and bottom are uniform. Recently, customers have always raised the problem of coating delamination, how to solve it? The layering phenomenon of coatings is an important problem often encountered in the process of production, storage and use. It not only affects the opening effect, but also changes the performance of the coating, which deviates from the target value. Serious hard precipitation, causing the paint to be scrapped and unusable.
So what is the cause of the delamination of the paint? How can we solve this situation?
1. It is caused by the change of pH value caused by exposure to air after opening the can.
2. There is a problem with the product formula. It has a great relationship with the selection of raw materials, formula design, specific gravity design, selection of fillers and pigments, selection of settling aids and other aids in the production process.
3. It may be a problem in the transportation process. The transportation process is a low-speed shearing process, which will accelerate the precipitation of powder.
4. Other reasons, such as the reasons for sedimentation due to poor physical properties of the coating: the low shear viscosity of the coating is too low; the resuspendability of pigments and fillers is poor.
1. For compatibility, the formula can be tested before formula design. For the specific gravity problem, polyamide wax pulp (oily, such as Dicai’s 9600-26X) or rheology modifier (water-based, such as Dicai’s D501) can be used to anchor to ensure that the components with heavy specific gravity do not sink, and the components with light components Do not float.
2. A better solution is to add as much as possible in the order of density from small to large when preparing coatings. In addition, the selection of wetting and dispersing agents is reasonable, and associative polyurethane thickeners are added to solve delamination, and the effect is also obvious.
3. For different systems and pigments and fillers, it can help to prevent sedimentation by selecting appropriate anti-settling additives and dispersants.
4. The phenomenon of hard precipitation is the most undesirable, and it is necessary to consider replacing the dispersant. It will destroy the design of the formula, so the most effective way to prevent the coating from settling is to increase the radius of the pigment and filler particles. You can choose a high molecular weight multi-branched dispersant to adsorb on the surface of the pigment and filler particles to increase its steric hindrance. Repulsive force, reducing settlement.
5. The solution is to use dispersant, thickener and anti-settling agent to solve the problem. However, no matter what kind of system, the phenomenon of stratification will appear after a long storage time. Therefore, preventing delamination is mainly a problem within a certain period of time. For a long time, it is mainly to prevent hard precipitation, which can be treated with some non-ionic dispersants.
6. Water-based interior wall latex paint commercial paint, especially pay attention to this problem. Thickening system high, medium and low shear should be well matched, and at least two should be matched. And the compatibility of auxiliary system, powder and emulsion is better. The most important thing is to test the storage stability.
7. Use base stock with high viscosity and high solids content. If the viscosity of the base material is small, an external thickener can be used to slow down the sedimentation rate of the pigment particles; the pigment particles are ground as finely as possible during the production process; light pigments and deionized water are used; surface.
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