Advantages and disadvantages of waterborne coatings

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Waterborne coatings are a relatively new type of coatings on the coatings market. Many people do not have a correct understanding of waterborne coatings. Waterborne coatings have the following characteristics compared to solventborne paints:

advantage

1. Water-based paint uses water as solvent to save a lot of resources; water-based paint eliminates fire hazard during construction; reduces air pollution; water-based paint uses only a small amount of low-toxic alcohol ether organic solvent to improve working environment conditions. The general water-based coating organic solvent (accounting for coating) is between 10% and 15%, and the current cathodic electrophoretic coating has been reduced to less than 1.2%, which has a significant effect on reducing pollution and saving resources.

2. Water-based paint can be directly applied on wet and wet environments; water-based paint has good adaptability to material surface and strong coating adhesion.

3. Water-based paint coating tools can be cleaned with water, greatly reducing the consumption of cleaning solvents.

4. The waterborne coating electrophoretic coating film is uniform and flat. Good flattening; inner cavity, weld seam, edge and edge parts can be coated with a certain thickness of coating film, which has good protection; electrophoretic coating film has the best corrosion resistance, thick film cathodic electrophoretic coating Salt spray resistance up to 1200h.

Problem

1. Water-based paints require high cleanliness during construction and material surface. Due to the large surface tension of water, dirt can easily cause shrinkage of the coating film;

2. The dispersion stability of water-based paint against strong mechanical force is poor. When the flow velocity in the conveying pipe changes sharply, the dispersed particles are compressed into solid particles, causing pitting of the coating film. The conveying pipe is required to have a good shape and the pipe wall is free from defects.

3. Water-based paints are highly corrosive to coating equipment and require corrosion-resistant lining or stainless steel. The equipment is expensive. The water-based paint corrodes the conveying pipe, the metal dissolves, the dispersed particles are precipitated, and the coating film produces pitting, and a stainless steel pipe is also required.

4. The baking type water-based paint has strict requirements on the construction environment conditions (temperature and humidity), increases the input of the temperature-regulating and humidity-conditioning equipment, and also increases the energy consumption.

5. The latent heat of evaporation of water-based paint water is large, and the baking energy consumption is large. Cathodic electrophoretic coatings need to be baked at 180 ° C; while latex coatings are completely dry for a long time.

6. Organic cosolvents with high boiling points of water-based paints produce a lot of soot during baking. After condensation, dripping on the surface of the coating film affects the appearance.

7. The water-based paint has a problem of poor water resistance, which makes the stability of the paint and the bath poor, and the water resistance of the film is poor. The medium of the aqueous coating is generally slightly alkaline (ph 7.5 ~ ph 8.5), the ester bond in the resin is easily hydrolyzed to degrade the molecular chain, affecting the stability of the coating and the bath, and the performance of the coating film.

Although there are many problems in water-based paints, some problems have been prevented in the process through the continuous improvement of the formulation, coating process and equipment, and some have been improved and improved by the formulation itself.


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