Any waterproof coating product has a shelf life. If there is a problem after this shelf life, how to prevent the polyurethane waterproof coating from deteriorating? First, understand why it deteriorates and deteriorate.
1 The moisture content of the production filler is too high;
2 production operation process (including feeding sequence, reaction temperature and time, etc.) out of control;
3 diluent does not meet the urethane level requirements;
4 The paint packaging drum leaks, and moisture or moisture in the air is mixed;
5 The packed drum contains reactive active substances such as water, alcohol, acid and the like.
Prevention and solution:
1 The raw material specifications must meet the formulation and process requirements, and strictly control the moisture content of the filler;
2 strictly in accordance with the process conditions, the feeding sequence, reaction temperature and time are controlled within the specified range;
3 Grasp the control of product packaging management and storage conditions.
2 crust
The phenomenon that the coating forms a hard coating film on the surface during storage is called crust. The reasons for this are:
1 The coating packaging drum is not tightly sealed or there is blisters in the packaging drum;
2 The catalyst is used improperly or in excessive amounts.
Prevention and solution to prevent skin crusts from forming:
1 use a suitable catalyst in production, and strictly control the amount of catalyst;
2 The paint packaging drum should be tightly sealed to prevent air from entering;
3 can be added anti-skinning agent butanone oxime, cyclohexanone oxime and so on.
3 precipitation
The pigment and the resin are separated into two distinct layers, and the phenomenon that the underlying pigment sometimes agglomerates cannot be stirred up. The reasons for this are:
1 The viscosity of the coating is small, the amount of the diluent is too large, and the resin content is small;
2 the pigment has a relatively high density and the particles are too thick;
3 pigments have poor wettability;
4 storage time is too long.
Prevention and solution:
1 Add an appropriate amount of anti-settling agent for coatings such as organic bentonite;
2 to improve the fineness of the pigment, adding a suitable pigment filler wetting agent;
3 Periodically put the paint bucket upside down or horizontally during storage. Stir the paint evenly before use. It should be used within the specified time.
4 sag
When applied on a vertical façade, some of the paint flows down, creating a phenomenon similar to tearing or hanging curtains called sagging. Causes of sag:
1 construction viscosity is too low;
2 Use solvents that are too volatile or too slow. The solvent that is too volatile is often evaporated before the coating film is completely leveled, and the solvent that is too volatile is used. The fluidity of the coating on the vertical surface is large, and a punctum or curtain is formed.
3 The construction site temperature is too low or the humidity is too high;
4 The coating contains too much heavy pigment, and the wettability of the pigment is not good;
5 The coating is applied too thick at a time.
Measures to prevent sag during paint application:
1 appropriate increase in the amount of thickener;
2 control the appropriate construction viscosity;
3 The construction environment temperature is preferably (20~30) °C;
4 The coating film should not be too thick at one time, and it should not exceed 0.5mm;
5 adjust the evaporation rate of the diluent, pay attention to the use of volatile solvents
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