Microwave/hot air collaborative drying method of paste-like coating

Abstract

The invention relates to a microwave / hot air collaborative drying method of a paste-like coating, which belongs to the technical field of microwave heating application. the method comprises the following steps of: respectively adjusting microwave power and hot air volume for a coating with water content of 75-90 wt% in a preheating drying stage, a constant speed drying stage and a decelerating drying stage according to water evaporation rate and water diffusion rate in the coating; and fast and deeply drying the coating at a lower temperature. Compared with other drying methods, the microwave-hot air collaborative low temperature fast and deep drying method of the paste-like coating, which is provided by the invention, has the advantages of energy conservation, environment friendliness and high drying speed; and because the drying temperature is lower, high temperature oxidization of a coating metal substrate can be effectively avoided.

Description

technical field [0001] The invention relates to a microwave / hot air co-drying method for a slurry coating, and belongs to the technical field of microwave heating applications. Background technique [0002] Today's coatings have become the top five synthetic materials along with plastics, adhesives, synthetic rubber, and synthetic fibers. The paint industry is a high-tech industry, and its development level is one of the symbols of the developed level of a country's chemical industry. The volatile organic compounds emitted by the paint into the air when it dries to form a film pose a serious threat to the human ecological environment. For this reason, countries around the world have formulated corresponding environmental protection regulations according to their own characteristics to limit the emission of VOC in coatings. The research of coatings is also developing toward water-based, high-solid differentiation, high-performance and functional. The slurry coating is wide...

AI Technical Summary

Problems solved by technology

The slurry coating is widely used in water-based coatings, solvent-based paints, rubber, chemical fiber coloring, plastics, construction, and metal materials due to its advantages of easy dispersion, convenient coating, heating and curing, and room temperature drying. However, due to the complex composition of slurry coatings, high water content, and relatively strict requirements for film-forming performance, it has brought technical difficulties to the rapid drying of coating films, which has seriously restricted the development of the coating industry.

[0003] Slurry coatings generally need to be heated to a certain temperature to meet the requirements of drying moisture content and surface quality of the coating. Conventional heating methods generally include radiation heating, forced convection heating and radiation heating combined with forced convection heating. The traditional heating method is to heat the workpiece or make the temperature in the heating furnace equal to or slightly higher than the temperature required for drying the coating. The heating speed is slow, and the coating film is prone to uneven heating and cracks, which seriously restricts the drying of the coating. production efficiency

Moreover, the drying energy consumption is high, and continuous production cannot be realized

[0004] In the known drying process, whether it is radiant heating or convective heating, the heat transfer is from the surface to the inside, and it takes a long time to remove moisture, which reduces the drying efficiency; especially for deep drying, it is usually necessary to dry the workpiece Heating to a higher temperature can dry to the inside of the coating, and for some coatings, chemical reactions or solvent volatilization are prone to occur when the coating reaches a certain temperature, which is undoubtedly the difficulty of drying coatings with high moisture content