Phenylpropylene emulsion uses water as the medium, which is inexpensive and safe, and is conducive to stirring and heat transfer, conveying and continuous production; the rate of polymerization is fast, the molecular weight of the product is high, and polymerization can be carried out at a lower temperature.
Slowly add defoamer to the material while stirring.
The amount should be appropriate. If the amount is too much, it will cause shrinkage, shrinkage, poor brushability and poor recoatability. If the amount is too small, the foam will not be eliminated, which will cause fish eyes. It is necessary to be good at distinguishing the problems caused by too much or too little defoamer from the defects and ills of the coating film, and find out the correct dosage. In addition, it is necessary to be good at identifying some defects of the coating film, such as oil shrinkage, edge shrinkage, etc., which are caused by the poor compatibility of the selected defoamer and improper selection of varieties.
Some defoamers are not dangerous goods. Some low-end products have a distinct smell of fire oil and are considered dangerous goods. When adopting, ask the supplier how to store and transport to ensure safety.
In the production of latex paint, the defoamer is generally added in two stages, namely, evonik polyethylene wax the stage of grinding and dispersing the pigment to prepare the pigment slurry and the stage of mixing the emulsion in the pigment slurry. Generally it is half of the total amount added at each stage, but it can also be adjusted according to the situation. It is best to use a defoamer with great foam suppression effect in the stage of grinding and dispersing the pigment paste, and it is best to use a defoamer with great foam breaking effect in the paint-forming stage. However, at present, many domestic latex paint manufacturers use the same type of defoamer, and the effect is also good, indicating that foam breaking and foam suppression can be accomplished by the same type. To illustrate the problem, we now introduce these two types of foreign defoamers.
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