There are two types of coatings that require a curing agent to cure into a film. The first category is that the curing agent has been added when the paint is made in the paint factory. This type of paint generally does not need to be packaged, but some paints are limited by the storage period. It often needs to be baked to dry into a film. Like most closed polyurethane paints, amino paints. The second category is that the curing agent can only be added before painting. It is often packaged, such as unsaturated polyester paint, hydroxyl curable polyurethane paint, etc. To use the curing agent reasonably, the following points should be paid attention to:
1) There must be a strict ratio between the amount of paint and curing agent. Too much curing agent will reduce the toughness of the paint film and affect the service life. If there is too little curing agent, the paint film will be sticky or even persist for a long time. Even if the film is barely formed, the mechanical properties and chemical resistance of the paint film will be greatly reduced. When painting, the paint should be mixed according to the ratio required by the product manual, and it should be fully stirred evenly.
2) After the paint is prepared, it should be stored for a period of time before construction. For S1-6 polyurethane varnish, it should be stored for 30-60 minutes after the paint is mixed before construction. This storage period is generally referred to as the "ripening period". The length of the curing period is affected by the ambient temperature. The curing period is longer when the temperature is low, otherwise the curing period can be shorter.
3) Once the curing agent is added, the coating starts to cure. After the paint is prepared, it should be used up within the specified time. Otherwise, the viscosity of the paint will increase rapidly, and it cannot be used and scrapped. This usable time after adding the curing agent is generally called "activity period" or "service life". The service life of S01-6 is about 8 hours. Obviously, it is also affected by the ambient temperature. For this type of paint, it should be prepared and used immediately, and how much is used.
Construction experience shows that when the prepared coating is about to reach the end of its service life, phenomena such as air bubbles, heat generation, rapid increase in viscosity, difficulty in brushing, and rapid deterioration of leveling will occur. Sometimes due to wrong paint or high ambient temperature. The above-mentioned signs will also appear in the paint that has just been prepared. At this time, it should be cooled quickly, quickly divided into packages, and constructed separately, and sometimes an appropriate thinner can be added to reduce the viscosity. Most of these methods are to prolong the use time and avoid wasting paint.
4) This type of coating that cures at room temperature can also be cured by heating. Heating and curing can improve the adhesion and work efficiency of the paint film, but it also increases the brittleness of the paint film.
5) Brushing tools and paint storage containers should be cleaned immediately after construction, and it will be difficult to clean after a while. Because these coatings are often polymerized and cured, what is produced is a three-way network cross-linked polymer that is insoluble or even insoluble.
