What is the main difference between a one-component polyurethane and a polymer cement-based waterproof coating?
One-component moisture-curing polyurethane resin coating, can be dry at low temperatures, theoretically below 0 ℃ can also be cured and dried. In practical applications, due to the surface of the coating by the ice limit (the surface of the coating if the water, below 0 ℃ will be frozen), is not easy to construction, generally not less than 0 ℃ when the normal construction. Relative humidity in the range of 30% -98%, single-component moisture curing polyurethane resin coating drying curing. Not affected. In the winter, fog, and even in the rainy day of the wet construction surface can also be a good construction, the normal dry curing, after the construction of 1-2h after the touch can be dry. The coating is wet curing type, and its curing drying is affected by the humidity in the air, if the air humidity is less than 30%, the curing of the film is much slower, and sometimes curing is not complete, the film performance by Impact; humidity is too high, dry curing speed too fast, the construction and storage to bring a lot of difficulties, especially in the high temperature
The paint is heated by moisture in the air drying, the higher the humidity in the air, the shorter the curing time. The higher the density of a NCO group in the coating, the more the molecular branch, the smaller the molecular weight, the higher the cross-linking density of the film, the film becomes harder and brittle, the higher the resistance to chemical corrosion, The better the wear resistance. The paint film is too hard and brittle. The use of 1,4-butanediol, 1,5-pentanediol, binary polyether prepared by the temperature curing polyurethane resin coating, the film hardness is reduced, can improve the flexibility of the film.
The definition of a one-component moisture-cured polyurethane resin coating is a reaction consisting of a hydroxyl-containing macromolecule compound such as a polyether ester resin, a polyester resin, an epoxy resin, castor oil, etc. and an excess of a polyisocyanate compound (reaction-NCO group and An OH-based animal husbandry ratio, i.e., NCO / OH & gt; 1), to produce a polyisocyanide prepolymer having an NCO group as an end group. When the prepolymer is applied on the surface of the object, the moisture in the air reacts with an NCO group in the prepolymer to form urea bonds to cure the film.
One-component wet-curing polyurethane resin coating construction is simple, the substrate treatment requirements are not too strict, the surface of the construction material without clean water, construction ingredients do not strictly measured.