Common sense of coating: deep analysis of the causes of emulsion paint cracking

Core tip: in the construction process of interior and exterior wall latex paint, the cracking of paint film after drying is a common problem, which is manifested as small cracks in part or in the whole, and even large peeling off of paint film After cracking, the paint film loses its original protective and decorative functions It is difficult to repair the cracked or peeled paint film directly It is often necessary to polish off the whole cracked coating and recoat it, resulting in waste of raw materials, increased cost and extended construction period The causes of emulsion paint cracking are caused by many factors, including external factors such as environment and construction, and internal factors such as formula design of emulsion paint itself First, Which is the price of Dajin diatom mud Recommended brief introduction: which is the price of Dajin diatom mud? How to buy genuine diatom mud? Guangdong diatom mud agent suggests placing a basin of cold water in the air conditioning room, so that the diatom mud wall can breathe effectively The feature of the breathing wall is obvious When the indoor air is dry, the diatom mud wall will release the absorbed water quickly Put it out to help regulate the indoor dry humidity It is suggested to place a basin of cold water in the air conditioning room, so that the wall of diatom mud can breathe effectively The feature of the wall that can breathe is obvious When the indoor air is relatively dry, the wall of diatom mud will absorb the water Paint Home News: in the construction process of interior and exterior wall latex paint, the paint film cracking after drying is a relatively common problem, which is manifested as small cracks in part or in the whole, and even the paint film will appear large peeling off After cracking, the paint film loses its original protective and decorative functions It is difficult to repair the cracked or peeled paint film directly It is often necessary to polish off the whole cracked coating and recoat it, resulting in waste of raw materials, increased cost and extended construction period The causes of emulsion paint cracking are caused by many factors, including external factors such as environment and construction, and internal factors such as formula design of emulsion paint itself First, the influence of latex paint formulation 1 PVC and CPVC PVC is the pigment volume concentration, CPVC is the critical pigment volume concentration These two data are important parameters of latex paint formulation After the latex paint is dried, the water evaporates completely In the final dry paint film, the pigments and fillers play the role of skeleton, while the base materials play the role of adhesion Therefore, the most important solid components in the latex paint are the pigments and fillers and the base materials If latex paint is in the vicinity of the CPVC area, the filling and parcel of the emulsion polymer is in the critical point of continuity and dispersion The drying of the paint film is easy to cause stress concentration, and the crack resistance of the paint film is poor Therefore, it is necessary to pay attention to the formulation of PVC and CPVC, and try not to leave PVC in the dangerous area near CPVC 2 Pigments Pigment is one of the most important solid components in latex paint Pigment can not only ensure the paint has good covering power and rich color, but also give the overall framework support ability of the film The film of paint without pigment is flexible, compact and integral If the pigment is added to the paint, the flexibility of the paint film becomes poor and fragile, especially for the finer powder, the overall tensile strength of the paint film is lower Therefore, when the other components in the paint formulation remain unchanged, the use of some coarser pigments can significantly improve the strength of the paint film and reduce the shrinkage stress, which is conducive to improving the cracking resistance of the formulation 3 emulsion The minimum film forming temperature (MFT) is an important parameter of emulsion If the outside temperature is lower than MFT, the polymer molecular chain activity ability is obviously limited, and the emulsion particles can not be extruded and fused properly, resulting in the emulsion not being able to form a film or not completely film-forming Therefore, the lower the MFT, the better the cracking resistance of the emulsion Second, the impact of construction environment 1 Temperature No matter what type of coating, there will be a construction temperature of 5 degrees -35 degrees If the ambient temperature is below or above the level, there will be some paint defects such as powder removal, cracking and poor adhesion Polymer emulsion has limited molecular chain activity, low flexibility and brittleness, and easy cracking 2 Humidity Generally, the construction is allowed only when the ambient humidity is below 85% When the construction is carried out in a high humidity environment, the water evaporation of the paint film is slow, which makes it difficult for the wet film of the emulsion paint to dry and form a film 3 Base material If the humidity of the substrate itself is too high, cracks will appear on the surface of the substrate with the evaporation of the substrate water after coating, and then cracks will appear on the surface of the paint film In addition, uneven substrate results in different thickness of wet film, and uneven thickness of wet film causes inconsistent shrinkage stress during drying, which leads to easy cracking of paint film Home of coatings is specialized in coatings, diatom mud, paint coating, coating technology, fire retardant coating news and coating, diatom mud, paint coating, coating technology, fire retardant coating decoration knowledge and decoration renderings,